US20240053094A1

US20240053094A1 - Method and apparatus for liquefying hydrogen

Info

Publication number: US20240053094A1
Application number: US18/277,796
Authority: US
Inventors: Axelle GAERTNER; Marie-Khuny Khy
Original assignee: LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Current assignee: LAir Liquide SA pour lEtude et lExploitation des Procedes Georges Claude
Priority date: 2021-02-18
Filing date: 2022-02-14
Publication date: 2024-02-15
Also published as: WO2022175204A1; FR3119883A1; FR3119883B1; CN116724208A

Abstract

In a hydrogen liquefaction process, a hydrogen-rich gas originating from an apparatus for separation by distillation and/or stripping and/or partial condensation, the gas exiting from the separation apparatus at a temperature of at most 103K containing at least 99.9 mol % of hydrogen and at a pressure between 20 and 30 bar, is sent to a hydrogen liquefier, without having heated the hydrogen-rich gas to a temperature above 0° C.

Description

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a § 371 of International PCT Application PCT/EP2022/053519, filed Feb. 14, 2022, which claims the benefit of FR2101587, filed Feb. 18, 2021, both of which are herein incorporated by reference in their entireties.

FIELD OF THE INVENTION

The present invention relates to a process and to an apparatus for the liquefaction of hydrogen, preferably integrated with the cryogenic separation of a mixture of carbon monoxide and hydrogen.

BACKGROUND OF THE INVENTION

The liquefaction of hydrogen is described in “Techniques de l′Ingenieur” [Engineering Techniques], chapter by Jean Gallarda, J3603.
The hydrogen is cooled and then liquefied in three stages:

- from ambient temperature down to 230K by a refrigeration unit;
- from 230K to approximately 80K by a first refrigeration cycle;
- from approximately 80K to approximately 20K by a second refrigeration cycle.

The exchange of heat between 300K and 20K takes place through brazed aluminum multipass plate exchangers.
The passages corresponding to the stream of gas to be liquefied contain catalyst and make it possible to carry out a continuous conversion of the hydrogen until a parahydrogen content of greater than 95% is achieved.
The cooling down to approximately 80K is carried out in a chamber thermally insulated with perlite. This cooling, called precooling, is carried out using a closed nitrogen cycle or with the cold of an addition of cryogenic liquid (generally liquid nitrogen) called “boosting”, both consuming a great deal of energy.
The cooling from approximately 80K to 20K is carried out in a vacuum chamber maintained at approximately 10⁻⁶mmHg, with the items of equipment of the chamber being surrounded by multilayer insulation. This cooling, which comprises the liquefaction, is carried out using a hydrogen or helium cycle. A nitrogen cycle, in particular, could not be used at such low temperatures.

SUMMARY OF THE INVENTION

An aim of the present invention is to reduce the energy consumption of the process and possibly to eliminate a portion of the equipment by eliminating the precooling stage.
According to a subject matter of the invention, there is provided a process for the liquefaction of hydrogen integrated with the cryogenic separation of a first mixture (1) of hydrogen and of another component, in which:

- i) the first mixture is cooled in an auxiliary heat exchanger down to at least 120K, the cooled first mixture is separated by partial condensation and/or by distillation and/or by stripping at a temperature below 120K in order to produce a flow rich in hydrogen containing at least one impurity at between 20 and 30 bar and the hydrogen-rich flow is purified at a cryogenic temperature of at most 103K to reduce its content of the at least one impurity in order to form a hydrogen-rich gas,
- ii) the hydrogen-rich gas originating from the apparatus for separation by distillation and/or stripping and/or partial condensation, the gas exiting from the separation apparatus at the temperature of at most 103K containing at least 99.9 mol % of hydrogen, preferably at least 99.99 mol % of hydrogen, indeed even at least 99.999 mol % of hydrogen and at a pressure between 20 and 30 bar, is sent to a hydrogen liquefier, without having heated the hydrogen-rich gas to a temperature above 0° C.,
- iii) the hydrogen-rich gas is cooled from the temperature of at most 103K and at the pressure between 20 and 30 bar in a first heat exchanger of the liquefier,
- wherein a hydrogen-rich flow is cooled in a second heat exchanger of the liquefier from a temperature of greater than 103K, preferably of greater than 0° C., and the cooled flow is subsequently cooled in the second heat exchanger, the hydrogen-rich gas is mixed with the hydrogen-rich flow having substantially the same pressure and composition as the hydrogen-rich gas and cooled in the second heat exchanger down to the temperature of the hydrogen-rich gas in order to form a second mixture and the second mixture is liquefied either in the first heat exchanger or after cooling in the first heat exchanger in order to form liquid hydrogen.

According to other optional aspects of the invention, which can be combined in any manner compatible with science and logic:

- the hydrogen-rich gas is purified by adsorption in order to remove the at least one impurity, which is carbon monoxide and/or nitrogen and/or methane,
- the first mixture comprises, as main components, hydrogen and carbon monoxide and possibly methane and/or nitrogen, the hydrogen-rich gas is withdrawn from a distillation or stripping column or
- from a phase separator, said column or separator operating at between 20 and 30 bar abs, the process is kept cold at least partially by a refrigeration cycle, the fluid of the cycle being heated and cooled in the first heat exchanger and optionally in a second heat exchanger,
- the liquefied hydrogen is stored in a storage tank, the boil-off gas of which is heated in the first and second heat exchangers,
- the hydrogen-rich gas is liquefied in the first heat exchanger or downstream of the latter inside a first insulated chamber and the first mixture is cooled and/or separated and optionally the hydrogen-rich flow is purified inside a second insulated chamber,
- the hydrogen-rich gas is mixed with a hydrogen-rich flow having substantially the same pressure, temperature and composition and the second mixture is liquefied in the first heat exchanger or after cooling in the first heat exchanger,
- the hydrogen-rich flow is cooled in the second heat exchanger and subsequently is mixed with the hydrogen-rich gas,
- the hydrogen-rich gas is not mixed with another gas upstream of the first heat exchanger.

According to another subject matter of the invention, there is provided a hydrogen liquefaction apparatus comprising a liquefier comprising a first heat exchanger, an apparatus for separation by distillation and/or stripping and/or partial condensation, means for sending a hydrogen-rich gas originating from the apparatus for separation by distillation and/or stripping and/or partial condensation at a temperature of at most 103K containing at least 99.9 mol % of hydrogen, preferably at least 99.99 mol % of hydrogen, indeed even at least 99.999 mol % of hydrogen and at a pressure between 20 and 30 bar to the hydrogen liquefier, without having heated the hydrogen-rich gas to a temperature above 0° C., and means for sending the hydrogen-rich gas to be cooled from the temperature of at most 103K and at the pressure between 20 and 30 bar in the first heat exchanger, characterized in that it comprises a second heat exchanger, means for sending a hydrogen-rich flow to be cooled in the second heat exchanger, means for mixing the hydrogen-rich gas with the hydrogen-rich flow cooled in the second heat exchanger and having substantially the same pressure, temperature and composition as the hydrogen-rich gas in order to form a second mixture and means for sending the second mixture to be liquefied in the first heat exchanger or after cooling in the first heat exchanger to be liquefied in order to form liquid hydrogen.
The first exchanger is preferably located in a first thermally insulated chamber and the second exchanger is located in a second thermally insulated chamber, the point where the hydrogen-rich gas and the hydrogen-rich flow mix being located outside the first and second chambers.
The apparatus can comprise comprising a refrigeration cycle using helium or hydrogen in order to cool and optionally to liquefy the second mixture.
By feeding the liquefaction process with a hydrogen-rich gas available at the required pressure and at the required temperature, it is possible to reduce the size of the heat exchanger of the precooling, indeed even to eliminate it altogether, if all the feed gas comes from an external source already the right pressure and the right temperature.
The means for liquefying the cooled gas in order to form liquid hydrogen can be constituted by the first heat exchanger and/or by expansion means downstream of the latter.
The expansion means are preferably located in the same insulated chamber as the heat exchanger but may be in a dedicated thermally insulated chamber.

BRIEF DESCRIPTION OF THE DRAWINGS

These and other features, aspects, and advantages of the present invention will become better understood with regard to the following description, claims, and accompanying drawings. It is to be noted, however, that the drawings illustrate only several embodiments of the invention and are therefore not to be considered limiting of the invention's scope as it can admit to other equally effective embodiments

FIG. 1 illustrates a cryogenic separation process for producing hydrogen.

FIG. 2 and FIG. 3 very diagrammatically illustrate processes for the liquefaction of hydrogen originating, for example, from the process of FIG. 1 .

DETAILED DESCRIPTION OF THE INVENTION

[FIG. 1 ] shows a process using a phase separator 9, a methane scrubbing column 15, a stripping column 25 and a column for the separation of carbon monoxide and methane 45, containing for example structured packings for the columns and which are capable of operating at cryogenic temperatures.
The synthesis gas 1 containing carbon monoxide, methane and carbon monoxide is purified of water and/or of carbon dioxide in the purification unit 3 before arriving at the heat exchanger 7, where it is cooled down to a cryogenic temperature and partially condensed.
The two phases are separated in a phase separator 9, in order to form a gas 11 enriched in hydrogen and a liquid depleted in hydrogen 13. The gas 11 is sent to the bottom of the methane scrubbing column 15, which produces a gas 19 enriched in hydrogen which is heated in the exchanger. A part of this gas 19 serves to regenerate the purification unit 3.
At least one intermediate gas 210, 211 withdrawn from the column 15 is cooled in a heat exchanger 23 by heat exchange with a fluid of the process, in this instance the liquid 51.
The bottom liquid 17 from the column 15 joins the liquid 13 from the separator 9 and the mixture 91, containing between 1 mol % and 3 mol % of hydrogen, is sent to the top of a stripping column 25. An overhead gas 27 from the stripping column contains at least 95 mol % of hydrogen and also carbon monoxide, nitrogen and methane. It is at between 20 and 30 bar, which is the operating pressure of the column 25, and has a temperature between 103K and 120K. The gas 27 is not heated but is purified in an adsorption unit 29 operating at cryogenic temperatures in order to remove carbon monoxide and/or methane and/or nitrogen in order to provide a gas 31 capable of being liquefied containing at least 99.9 mol % of hydrogen, preferably at least 99.99 mol % of hydrogen, indeed even at least 99.999 mol % of hydrogen. A purification of this type is described in “The low temperature removal of small quantities of nitrogen or methane from hydrogen gas by physical adsorption on a synthetic zeolite”, Kidnay et al., AIChE Journal, Vol. 12, No. 1, January 1966.
A liquid 33 taken at the bottom of the stripping column 25 is cooled in the exchanger 7 and is sent to the separation column 45. Another part of the same liquid 35 is vaporized in a bottom reboiler 37 and is returned at the bottom of the stripping column.
The separation column comprises several sections for separation by distillation and optionally a vessel 99. It has a bottom reboiler 73 which serves to heat the bottom liquid 75, the gas formed being returned to the bottom. The bottom liquid 77 enriched in methane is divided into two. A part 83 is evaporated in the exchanger 7 in order to form fuel. The remainder 85 is pressurized by a pump 87 and is sent to the top of the scrubbing column 15.
The overhead gas from the column 43 enriched in carbon monoxide is sent to a product compressor 57, which produces a gas enriched in carbon monoxide 57. A part of the gas enriched in carbon monoxide 61 is cooled and is divided into two. A part 65 is expanded in a turbine 67 in order to provide cold. The expanded gas 89 is returned to the inlet of the compressor 57. The remainder of the gas 69 continues its cooling in the exchanger 7 and serves to heat the reboilers 73 and 37 (flows 93 and 73). The gas which has served for the reboiling is thus partially condensed and feeds, as flow 97, the vessel 99 at the top of the separation column 45. The gas 41 from the vessel 99 feeds the compressor 57. The liquid 47 from the vessel 99 is sent to a phase separator 49, the liquid 51 from the separator serves as refrigerant in the heat exchanger 23 in order to cool the intermediate gases 21A, 21B, 21C as well as the overhead gas 27 from the stripping column.
A liquid withdrawn from the separation section of the separation column can replace the liquid 47 or another liquid of the process.
It will be understood that there exist many processes which make it possible to separate a first mixture of hydrogen and carbon monoxide as main components, possibly also containing nitrogen and/or methane. If these processes make it possible to produce hydrogen at a cryogenic temperature and at a pressure compatible with those of the liquefier, the hydrogen produced can be purified at cryogenic temperature and sent to the liquefier as feed gas.
For example, hydrogen 27 can be produced by a phase separator at between 20 and 30 bar abs in a partial condensation process optionally combined with a distillation.
Other separation processes are also capable of supplying hydrogen at a cryogenic temperature and at a pressure between 20 and 30 bar, for example the separation of purge gas from an ammonia production process.
As the hydrogen exits from the chamber of the cold process at low temperature, additional cold will have to be provided compared to a process where the hydrogen is heated up to ambient temperature. This is carried out by increasing the production of cold. For the case of a cryogenic separation of carbon monoxide and hydrogen, it is necessary to increase the CO (or N₂) cycle flow rate.
The hydrogen produced at low temperature and at a pressure between 20 and 30 bar can be purified in the thermally insulated chamber in which the separation column and/or the phase separator from which it originates is/are located. Otherwise, and in particular in the case of the modification of an existing apparatus, the hydrogen can exit from the chamber where the separation column and/or the phase separator from which it originates is/are located and be sent by at least one thermally insulated pipe into a chamber 102 containing the purification apparatus in order to reduce its content of impurities, for example at least one of carbon monoxide, methane and nitrogen.
The “cold” purification is a necessary stage in order to remove all the impurities which might freeze along the exchange line which goes down to approximately 20K, and consequently clog the heat exchangers.

TABLE 1

Mean molar purity	Range of possible purities	Purity after
before purification	before purification	purification

H₂	98%	95% to 99%	>99.999%
CO	0.4%	ppm to 1%	<10 ppb
CH₄	1.2%	0.5% to 3%	<10 ppb
N₂	0.4%	ppm to 1%	<10 ppb

The purification of gaseous hydrogen with a unit of TSA (temperature swing adsorption) type is normally possible at 80K (where the adsorption capacity is high). Removing 2%, indeed even 1%, of impurities involves short cycles (of a few hours) and a high regeneration flow rate.
[FIG. 2 ] shows a first alternative form of the process according to the invention where the flow 27 of [FIG. 1 ] feeds a liquefaction process as sole feed fluid.
The gaseous purified hydrogen 27 exits either from the thermally insulated chamber E in which the separation column and/or the phase separator C from which it originates is/are located or from a dedicated purification chamber 102 at a pressure between 20 and 30 bar abs.
Without being heated to a temperature above 0° C., preferably above −50° C., indeed even above −100° C., indeed even without having been heated at all, and preferably without being compressed, it passes through at least one thermally insulated pipe into another thermally insulated chamber 104 where it will be liquefied.
This chamber 104 contains a brazed aluminum multipass plate heat exchanger 101.
The passages corresponding to the stream of gas to be liquefied contain catalyst and make it possible to carry out a continuous conversion of the hydrogen until a parahydrogen content of greater than 95% is achieved.
The chamber 104 is under vacuum maintained at approximately 10⁻⁶mmHg, the items of equipment inside the chamber being surrounded by multilayer insulation. This cooling which is carried out therein comprises the liquefaction and is carried out using a hydrogen or helium cycle.
The exchanger 101 can simply contain at least one passage for cooling and liquefying the hydrogen, all the hydrogen being produced in liquid form and removed as product 111, and also the passages necessary for the refrigeration cycle or cycles.
The purified hydrogen can be introduced at the hot end of the heat exchanger 101.
It will thus be understood that, if the purified hydrogen is the only source of hydrogen to be liquefied or if all the hydrogen to be liquefied is available at the temperature of the hydrogen to be purified, no precooling will be necessary and the second conventional exchanger for cooling the hydrogen down to approximately 120K with its nitrogen cycle or other refrigerant cycle will not be required.
In other cases, as illustrated in [FIG. 3 ], the second exchanger 103 will be present but preferably the purified hydrogen 27 coming from the low-temperature separation will be mixed with the hydrogen-rich flow 127 cooled in the second exchanger outside the chamber 106 of the second exchanger 103 and subsequently the mixture formed will be cooled in the liquefaction heat exchanger 101 inside the chamber 104.
The hydrogen-rich flow 127 is cooled by traversing the second exchanger 103 from the hot end to the cold end and a common cycle 105 provides cold for the first and second exchangers while a cycle 107 provides cold solely for the second exchanger 103.
The particulars of the cooling cycles are not given for the exchangers 101, 103 of the figures, these cycles being copiously described in the literature, for example “Principles for the liquefaction of hydrogen with emphasis on precooling processes” by Walnum et al., IIR Conference, 2012, Berstad, D. O., J. H. Stang and P. Nekså, Large-scale hydrogen liquefier utilising mixed-refrigerant pre-cooling, International Journal of Hydrogen Energy, 2010, 35(10), pp. 4512-4523, Quack, H., Conceptual design of a high efficiency large capacity hydrogen liquefier, Advances in Cryogenic Engineering: Proceedings of the Cryogenic Engineering Conference—CEC, 2002, Madison, Wisconsin (USA): AIP, EP 3 339 605, EP 3 368 630, EP 3 368 631, EP 3 368 844, EP 3 368 845 and EP 3 759 192.
The liquefaction of hydrogen as such, usually borne by the H2 cycle, can be:

- a) either directly carried out with the surplus of gaseous hydrogen which will not be liquefied (approximately 5000 Sm³/h at 29 bar can be liquefied per 50 000 Sm³/h of hydrogen at the same pressure). In this case, this excess (and ultrapure→no PSA required) hydrogen can be sent away to the customer at low pressure or partially at medium pressure at 6 bara, for example, or, by adding a hydrogen compressor, at pressures of at least 20+ bara),
- b1) or via an independent H2 cycle, for example where a large amount of liquid hydrogen is desired,
- b2) or via an independent He cycle.

The invention can also be used by modifying an existing apparatus for the separation of synthesis gas. It would be necessary to provide for increasing the size of the refrigeration cycle, the size of the turbines and the size of the cycle compressor coolers.
The use of boosting with liquid nitrogen can make it possible to provide the cold necessary for withdrawing one of the main products at sub ambient temperature.
Optionally, the synthesis gas 1 can be cooled at least partially in the heat exchanger 103 upstream of the separation.
Optionally, at least a part of the apparatus for separation by distillation and/or stripping and/or partial condensation can be arranged in the same thermally insulated chamber as the second heat exchanger.
The hydrogen to be liquefied is usually expanded at the end of cooling in a turbine and/or a valve. This last stage is not illustrated.
While the invention has been described in conjunction with specific embodiments thereof, it is evident that many alternatives, modifications, and variations will be apparent to those skilled in the art in light of the foregoing description. Accordingly, it is intended to embrace all such alternatives, modifications, and variations as fall within the spirit and broad scope of the appended claims. The present invention may suitably comprise, consist or consist essentially of the elements disclosed and may be practiced in the absence of an element not disclosed. Furthermore, if there is language referring to order, such as first and second, it should be understood in an exemplary sense and not in a limiting sense. For example, it can be recognized by those skilled in the art that certain steps can be combined into a single step.
The singular forms “a”, “an” and “the” include plural referents, unless the context clearly dictates otherwise.
“Comprising” in a claim is an open transitional term which means the subsequently identified claim elements are a nonexclusive listing (i.e., anything else may be additionally included and remain within the scope of “comprising”). “Comprising” as used herein may be replaced by the more limited transitional terms “consisting essentially of” and “consisting of” unless otherwise indicated herein.
“Providing” in a claim is defined to mean furnishing, supplying, making available, or preparing something. The step may be performed by any actor in the absence of express language in the claim to the contrary.
Optional or optionally means that the subsequently described event or circumstances may or may not occur. The description includes instances where the event or circumstance occurs and instances where it does not occur.
Ranges may be expressed herein as from about one particular value, and/or to about another particular value. When such a range is expressed, it is to be understood that another embodiment is from the one particular value and/or to the other particular value, along with all combinations within said range.
All references identified herein are each hereby incorporated by reference into this application in their entireties, as well as for the specific information for which each is cited.

Claims

1-12. (canceled)

13. A process for the liquefaction of hydrogen integrated with the cryogenic separation of a first mixture of hydrogen and of another component, wherein:

i) cooling the first mixture in an auxiliary heat exchanger down to at least 120K, the cooled first mixture is separated by partial condensation and/or by distillation and/or by stripping at a temperature below 120K in order to produce a flow rich in hydrogen containing at least one impurity at between 20 and 30 bar and the hydrogen-rich flow is purified at a cryogenic temperature of at most 103K in order to reduce its content of the at least one impurity in order to form a hydrogen-rich gas;

ii) sending the hydrogen-rich gas originating from the apparatus for separation by distillation and/or stripping and/or partial condensation, the gas exiting from the separation apparatus at the temperature of at most 103K containing at least 99.9 mol % of hydrogen and at a pressure between 20 and 30 bar, to a hydrogen liquefier, without having heated the hydrogen-rich gas to a temperature above 0° C.;

iii) cooling the hydrogen-rich gas from the temperature of at most 103K and at the pressure between 20 and 30 bar in a first heat exchanger of the liquefier;

iv) cooling a hydrogen-rich flow in a second heat exchanger of the liquefier from a temperature of greater than 103K to form a cooled flow; and

wherein the cooled flow is subsequently cooled in the second heat exchanger, the hydrogen-rich gas is mixed with the hydrogen-rich flow having substantially the same pressure and composition as the hydrogen-rich gas and cooled in the second heat exchanger down to the temperature of the hydrogen-rich gas in order to form a second mixture, and the second mixture is liquefied either in the first heat exchanger or after cooling in the first heat exchanger in order to form liquid hydrogen.

14. The process as claimed in claim 13, wherein the hydrogen-rich gas is purified by adsorption in order to remove the at least one impurity, which is carbon monoxide and/or nitrogen and/or methane.

15. The process as claimed in claim 13, wherein the first mixture comprises, as main components, hydrogen and carbon monoxide and possibly methane and/or nitrogen.

16. The process as claimed in claim 13, wherein the hydrogen-rich gas is withdrawn from a distillation or stripping column or from a phase separator, said column or separator operating at between 20 and 30 bar abs.

17. The process as claimed in claim 13, wherein the process is kept cold at least partially by a refrigeration cycle, the fluid of the cycle being heated and cooled in the first heat exchanger and optionally in a second heat exchanger.

18. The process as claimed in claim 13, wherein the liquefied hydrogen is stored in a storage tank, the boil-off gas of which is heated in the first and second heat exchangers.

19. The process as claimed in claim 13, wherein the hydrogen-rich gas is liquefied in the first heat exchanger or downstream of the latter inside a first insulated chamber and the first mixture is cooled and/or separated and optionally the hydrogen-rich flow is purified inside a second insulated chamber.

20. The process as claimed in claim 13, wherein the hydrogen-rich flow is cooled in the second heat exchanger from a temperature above 0° C.

21. The process as claimed in claim 13, wherein the hydrogen-rich flow is cooled in the second heat exchanger and subsequently is mixed with the hydrogen-rich gas.

22. A hydrogen liquefaction apparatus having a liquefier, the hydrogen liquefaction apparatus comprising:

a first heat exchanger;

a separation apparatus configured to separate a mixed fluid using a means selected from the group consisting of distillation, stripping, partial condensation, and combinations thereof;

means for sending a hydrogen-rich gas originating from the separation apparatus at a temperature of at most 103K containing at least 99.9 mol % of hydrogen and at a pressure between 20 and 30 bar to the hydrogen liquefier, without having heated the hydrogen-rich gas to a temperature above 0° C.;

means for sending the hydrogen-rich gas to be cooled from the temperature of at most 103K and at the pressure between 20 and 30 bar in the first heat exchanger;

a second heat exchanger;

means for sending a hydrogen-rich flow to be cooled in the second heat exchanger;

means for mixing the hydrogen-rich gas with the hydrogen-rich flow cooled in the second heat exchanger and having substantially the same pressure, temperature and composition as the hydrogen-rich gas in order to form a second mixture; and

means for sending the second mixture to be liquefied in the first heat exchanger or after cooling in the first heat exchanger to be liquefied in order to form liquid hydrogen.

23. The apparatus as claimed in claim 22, wherein the first exchanger is located in a first thermally insulated chamber and the second exchanger is located in a second thermally insulated chamber, the point where the hydrogen-rich gas and the hydrogen-rich flow mix being located outside the first and second chambers.

24. The apparatus as claimed in claim 22, further comprising a refrigeration cycle using helium or hydrogen in order to cool and optionally to liquefy the second mixture.