EP4330611A1

EP4330611A1 - Device and process for cooling a flow of a target fluid predominantly comprising dihydrogen, and associated use thereof

Info

Publication number: EP4330611A1
Application number: EP22726730.9A
Authority: EP
Inventors: Florian JALIA; Hamza FILALI; Audrey HUBERT
Original assignee: Engie SA
Current assignee: Engie SA
Priority date: 2021-04-30
Filing date: 2022-05-02
Publication date: 2024-03-06
Also published as: AU2022266084A1; BR112023022544A2; WO2022229470A1; FR3122487B1; FR3122487A1

Abstract

The device (100) for cooling a flow (101) of a target fluid predominantly comprising dihydrogen, comprises: - a first heat exchanger (105) configured to cool an intermediate refrigerant fluid (110) by heat exchange with an expanded dioxygen flow (115), - an intermediate closed circuit (120) for transporting the intermediate refrigerant fluid from the first heat exchanger to a second heat exchanger (125), - a means (130) for compressing the intermediate refrigerant fluid along the intermediate closed circuit, - the intermediate refrigerant fluid, configured to remain in the liquid or supercritical state at least when passing through the compression means and - the second heat exchanger configured to cool the flow of target fluid by heat exchange with the intermediate refrigerant fluid cooled in the first heat exchanger.

Description

DEVICE AND METHOD FOR COOLING A FLOW OF A TARGET FLUID COMPRISING MAJORITY OF DIHYDROGEN AND USE

ASSOCIATE

Technical field of the invention

The present invention relates to a device for cooling a flow of a target fluid mainly comprising dihydrogen, a method for cooling a flow of a target fluid mainly comprising dihydrogen and a corresponding use. It applies, for example, to the field of the liquefaction of dihydrogen obtained by electrolysis of water.

State of the art

Hydrogen is an energy vector produced mainly by reforming or gasification of hydrocarbons and in a minority by the electrolysis of water, the thermochemical dissociation of water or biomass. The growing use of renewable sources of electricity is encouraging the development of water electrolysis to promote carbon-neutral hydrogen. However, the hydrogen thus produced must subsequently be conditioned in order to be transported. One of these options is to liquefy it.

The hydrogen liquefaction process is divided into three main temperature technological blocks: compression, pre-cooling and refrigeration. The purpose of precooling is to lower the inlet temperatures located between 273 K and 320 K of the hydrogen fluid of interest and the fluid used for refrigeration in the following block, down to a so-called precooling temperature located between 78 K and 120K.

The electrolysis process generates, for each kilogram of hydrogen produced, eight kilograms of oxygen. This oxygen is in most cases released into the atmosphere, it is fatal oxygen.

Some systems use the fatal oxygen co-generated during the electrolysis of water to pre-cool the hydrogen liquefaction by expanding the compressed oxygen at the electrolyser outlet to atmospheric pressure. This operation makes it possible to lower its temperature to around 140 K. This oxygen can thus flow in the opposite direction into a heat exchanger from which it emerges at room temperature, thereby cooling the hydrogen. The oxygen is then released into the atmosphere.

The main drawback of these systems is the danger of crossing a flow of oxygen with a flow of hydrogen within the same heat exchanger (in the event of a leak in the exchanger, and in the event of an explosion to a greater extent). extreme).

An improvement of the previous systems proposes to use a buffer circuit. The oxygen thus cools, not the hydrogen directly, but an inert gas, preferably nitrogen, helium or neon, which in turn cools the hydrogen.

Nevertheless, this improvement imposes the additional or increased use of gas compressors in order to compensate for the pressure drops linked to the intermediate circuit.

There is therefore no economical solution (reduction in the size of the compressors) and increased energy efficiency for the liquefaction of dihydrogen and in particular for its pre-cooling cycle.

Patent application GB 2 142 423 is known, which discloses a device for cooling a stream using an intermediate refrigerant fluid. The intermediate refrigerant fluid is in gaseous form at ambient temperature at the inlet of a compressor and in supercritical form at the outlet of said compressor after it has cooled to ambient temperature.

Object of the invention

The present invention aims to remedy all or part of these drawbacks.

To this end, according to a first aspect, the present invention relates to a device for cooling a flow of a target fluid mainly comprising dihydrogen, which comprises:

- a first heat exchanger configured to cool an intermediate refrigerant by heat exchange with an expanded flow of oxygen,

- an intermediate closed circuit for transporting the intermediate refrigerant fluid from the first heat exchanger to a second heat exchanger,

- a means for compressing the intermediate refrigerant fluid along the intermediate closed circuit,

- the intermediate refrigerant fluid, configured to remain in the liquid or supercritical state at least when passing through the compression means and - the second heat exchanger configured to cool the flow of the target fluid by heat exchange with the intermediate refrigerant fluid cooled in the first heat exchanger.

Thanks to these arrangements, it is possible to set up a cooling buffer circuit between the flow of oxygen and the flow of hydrogen to avoid safety risks without, however, requiring a gas compressor to compress the intermediate refrigerant fluid. These provisions also make it possible to provide an economical solution (reduction in the size of the compressors) and with increased energy efficiency for the liquefaction of dihydrogen and in particular for its pre-cooling cycle by optimized recovery of the fatal oxygen co-produced during water electrolysis. In addition, these provisions allow a simplified operational implementation compared to existing solutions.

In embodiments, the intermediate refrigerant fluid is mainly:

- an n-pentane,

- an i-butane,

- an n-hexane,

- an n-heptane,

- an n-octane,

- a 2-methylpentane,

- a 2,2-dimethilbutane,

- acetone,

- ether,

- methanol,

- an n-butane or

- ammonia.

These embodiments make it possible to use a refrigerant fluid having a wide temperature range in the supercritical or liquid state.

The use of an n-pentane presents the most flexible use, that is to say that no concession is to be made to keep it in liquid form (lowest melting temperature).

The uses of an n-butane or ammonia are advantageous, but require the implementation of the compression means downstream of the first exchanger or else to reduce by part the cooling power of these intermediate refrigerants.

In some embodiments, the second heat exchanger is configured to cool the flow of target fluid with, in addition to the intermediate refrigerant fluid, a flow of refrigerant fluid, the device comprising a closed circuit of refrigerant fluid, this circuit comprising:

- a means for compressing the low-pressure refrigerant fluid at the outlet of the second compression means to form a high-pressure refrigerant fluid,

- a means of inserting the high pressure refrigerant fluid into the second heat exchanger,

- a means for expanding the high-pressure refrigerant fluid to form a low-pressure refrigerant fluid,

- a third heat exchanger configured to cool the flow of the target fluid by heat exchange with the low-pressure refrigerant fluid and - a means for inserting the low-pressure refrigerant fluid into the second heat exchanger.

These embodiments make it possible to improve the achievement of the cooling of the target fluid.

In some embodiments, the device that is the subject of the present invention comprises a fourth heat exchanger configured to cool the flow of the target fluid by heat exchange with the low-pressure refrigerant fluid coming from the high-pressure refrigerant fluid expansion means, the means for inserting the low pressure refrigerant fluid into the second heat exchanger being configured to insert the flow of low pressure refrigerant fluid from the fourth heat exchanger.

These embodiments make it possible to optimize the process of cooling the fluid gas.

In some embodiments, the device that is the subject of the present invention comprises the refrigerant fluid, this refrigerant fluid being mainly:

- nitrogen,

- argon,

- a mixture of nitrogen and argon or

- a mixture of hydrocarbons and nitrogen. In some embodiments, the device which is the subject of the present invention comprises a means for expanding the dioxygen upstream of the first heat exchanger.

These embodiments make it possible to obtain a flow of oxygen from an electrolysis process capable of cooling the refrigerant fluid.

In some embodiments, the device that is the subject of the present invention comprises a water electrolysis means, configured to produce dioxygen and dihydrogen, the dioxygen produced being supplied by means of dioxygen expansion.

These embodiments make it possible to generate both the fluid to be cooled and the oxygen by indirectly allowing the cooling.

In some embodiments, the device that is the subject of the present invention comprises means for injecting dihydrogen from the water electrolysis means into the second heat exchanger.

These embodiments make it possible to valorize renewable sources of electricity in order to generate hydrogen with a neutral carbon balance.

According to a second aspect, the present invention relates to a process for cooling a flow of a target fluid mainly comprising dihydrogen, which comprises:

- -a first stage of heat exchange to cool an intermediate refrigerant fluid by heat exchange with an expanded flow of oxygen,

- an intermediate stage of circulation in a closed circuit of the intermediate refrigerant fluid from the first stage of heat exchange to a second stage of heat exchange,

- a stage of compression of the intermediate refrigerant fluid during the intermediate stage of circulation in a closed circuit and

- the second stage of heat exchange for cooling the flow of the target fluid by heat exchange with the intermediate refrigerant fluid cooled during the first stage of heat exchange, the intermediate refrigerant being configured to remain in the liquid state or supercritical at least during the performance of the compression step.

This method has the same advantages as the device which is the subject of the present invention. According to a third aspect, the present invention aims at the use of a flow mainly of n-pentane in a supercritical or liquid state in a closed circuit to cool a body by accumulation of cold temperatures during the heat exchange between a flow mainly of n -compressed pentane and mainly a flow of oxygen.

This use has the same advantages as the device which is the subject of the present invention.

In embodiments, the body is predominantly hydrogen flux.

In embodiments, the body is predominantly a solid body. Brief description of figures

Other advantages, aims and particular characteristics of the invention will emerge from the non-limiting description which follows of at least one particular embodiment of the device and of the method which are the subject of the present invention, with reference to the appended drawings, in which:

- Figure 1 shows, schematically, a first particular embodiment of the device that is the subject of the present invention and

- Figure 2 represents, schematically and in the form of a flowchart, a particular succession of steps of the method which is the subject of the present invention.

Description of embodiments

This description is given on a non-limiting basis, each characteristic of an embodiment being able to be combined with any other characteristic of any other embodiment in an advantageous manner.

Note that the figures are not to scale.

It is noted here that the term “predominantly” designates a relative majority among other compounds or an absolute majority of a compound in a mixture. The term "predominantly" designates a composition comprising at least 30% of the designated compound.

In variants, the term “predominantly” denotes a composition comprising at least 40% of the designated compound. In variants, the term “predominantly” denotes a composition comprising at least 50% of the designated compound.

In variants, the term “predominantly” denotes a composition comprising at least 60% of the designated compound. In variants, the term “predominantly” denotes a composition comprising at least 70% of the designated compound.

In variants, the term “predominantly” denotes a composition comprising at least 80% of the designated compound.

In variants, the term “predominantly” denotes a composition comprising at least 85% of the designated compound.

In variants, the term “predominantly” denotes a composition comprising at least 90% of the designated compound.

In variants, the term “predominantly” denotes a composition comprising at least 95% of the designated compound. It is noted here that the target fluid 101 to be cooled is preferably predominantly a gas and, even more preferably predominantly hydrogen. Such a gas can also mainly be:

- methane,

- carbon dioxide, - carbon monoxide,

- nitrogen or

- argon.

In general, the fluid to be cooled can be any fluid or mixture of fluids whose boiling temperature is greater than 275K and the crystallization temperature is between 80K and 200K.

A diagrammatic view of an embodiment of the device 100 object of the present invention is observed in FIG. 1, which is not to scale.

It is noted that this device 100 forms the cooling device of a larger system (not referenced) comprising the systems for transporting, cooling and compressing the fluid to be precooled. In Figure 1, this system includes:

- an inlet 1025 for fluid to be cooled, the flow of fluid 101 passing successively through the second heat exchanger 125, the third exchanger 160 of heat and the fourth heat exchanger 180 when this fourth exchanger 180 is present,

- a fluid cooling stage 1010 with two outlets:

- an outlet for cooling fluid, which can be the fluid to be cooled, at low pressure 1020 and

- an outlet for medium-pressure cooling fluid 1015, the low-pressure 1020 and medium-pressure 1015 cooling fluid flows passing successively through the fourth heat exchanger 180 when present, the third heat exchanger 160 and the second heat exchanger 125 heat before reaching a 1005 stage of compression and

- Said compression stage comprising an outlet for high-pressure cooling fluid 1030, the flow of high-pressure cooling fluid passing successively through the second heat exchanger 125, the third heat exchanger 160 and the fourth heat exchanger 180.

It should be noted that devices of the same type, for example compressors or exchangers, may not be distinct devices, but stages of a single device for all or part of the devices of a given type. For example, the second exchanger 125, the third exchanger 160 and the fourth exchanger 180 can correspond to three distinct stages of a single exchanger.

It is noted that, in variants, the fourth exchanger 180 is absent from the device 100.

The device 100 for cooling a flow of a fluid comprises:

- a first heat exchanger 105 configured to cool an intermediate refrigerant fluid 110 by heat exchange with an expanded flow of oxygen 115,

- an intermediate closed circuit 120 for transporting the intermediate refrigerant fluid from the first heat exchanger to a second heat exchanger 125,

- a means 130 for compressing the intermediate refrigerant fluid along the intermediate closed circuit,

- the intermediate refrigerant fluid 110, configured to remain in the liquid or supercritical state at least when passing through the compression means and - The second heat exchanger 125 configured to cool the flow of the target fluid by heat exchange with the intermediate refrigerant fluid cooled in the first heat exchanger.

The first heat exchanger 105 is, for example, a plate, spiral, tube, tube bundle or finned exchanger. These examples are also applicable to the second, third and fourth heat exchangers, 125 and 160, and 180.

The intermediate refrigerant fluid 110 is selected for the ability of said fluid 110 to remain in a liquid or supercritical state at least under the action of the compression means 130. Preferably, this intermediate refrigerant fluid 110 remains in the liquid or supercritical state throughout the closed circuit 120.

In preferred embodiments, the intermediate coolant 110 is configured to have boiling and melting temperatures at atmospheric pressure of respectively greater than 300 K and less than at least 200 K.

In preferred embodiments, the intermediate coolant 110 is configured to have a mass flow rate ratio of 4.8 kg _n -

C5/kgi_H2.

Thus, depending on the dimensioning and type of compression means 130, the nature of the intermediate refrigerant fluid may vary. In preferred variants, the intermediate refrigerant fluid 110 is mainly:

- an n-pentane,

- an i-butane,

- an n-hexane,

- an n-heptane,

- an n-octane,

- a 2-methylpentane,

- a 2,2-dimethilbutane,

- acetone,

- ether,

- methanol,

- an n-butane or

- ammonia. In other variants, the refrigerant fluid 110 is mainly ammonia used at a pressure of less than 8 bara used over a range of 200 K - 300 K. This refrigerant fluid 110 is liquid after having been cooled by oxygen and can therefore be pumped and/or compressed. Ammonia, on the other hand, is gaseous at a temperature above approximately 240 K.

In other variants, the refrigerant 110 is mainly n-butane at a pressure of less than 1.5 bara which can be used in the 140 K - 300 K range. Like ammonia, n-butane is liquid after cooling. by oxygen and therefore can be pumped, but gaseous at a temperature above 283 K. It is thus possible to reach lower temperatures.

These variants involve using a cryogenic pump, the cost of which is a priori higher, but remains less than a compressor. These variants also imply an additional difficulty in the optimization of the process due to the management of the change of state.

In other variants, the intermediate refrigerant fluid 110 is routed to the second exchanger 125 by transporting the refrigerant fluid 110 not by pipe, but by mobile storage. This could be the case for island production of hydrogen whose liquefaction takes place elsewhere. The intermediate refrigerant 110 from the second exchanger 125 is then transported by transport to the first exchanger 105 (and optionally the means 130 of compression).

Preferably, the compression means 130 is positioned between downstream of the second exchanger 125 and upstream of the first exchanger 105 along the flow of the flow of fluid 110 refrigerant.

The flow mainly of oxygen 115 can come from a dedicated storage or, preferably, from a means 175 of water electrolysis. In all cases, the predominantly dioxygen flow 115 is preferentially expanded before being inserted into the first heat exchanger 105. This relaxation is ensured by means 170 of relaxation. Such expansion means 170 can be of any known type such, for example, an expansion turbine, an expansion valve or a turboexpander.

In variants, the predominantly dioxygen flow is released into the atmosphere once implemented in the first heat exchanger 105 . Thus, as is understood, in certain embodiments, the device 100 comprises a means 170 for expanding the dioxygen upstream of the first heat exchanger 105 .

In some embodiments, the expansion means 170 is configured to lower the pressure of the oxygen flow from 30 bara to 1.1 bara, preferably at ambient temperature. Such embodiments make it possible to lower the temperature of the oxygen flow to 119 K (-154° C.).

Additionally, as understood, in some embodiments, device 100 includes water electrolysis means 175 configured to produce oxygen and hydrogen, the produced oxygen being supplied to oxygen expansion means 170 . Such a means 175 of water electrolysis is, for example, an electrolyser. Preferably, the first heat exchanger 105 is positioned as close as possible to the electrolysis means 175 to reduce the pressure drops of the oxygen generated during the water electrolysis process.

Preferably, the mass flow rate ratio between the dioxygen and the dihydrogen generated by the electrolysis means 175 is configured to reach 8 kgo2/kgi_H2, as determined by the stoichiometry of the electrolysis reaction.

In embodiments, such as that represented in FIG. 1, the flow of target fluid 101 to be cooled is mainly dihydrogen, the device 100 comprising a means 1025 for injecting the dihydrogen resulting from the means 175 for electrolysis of the water in the second heat exchanger 125.

The closed circuit 120 has the function of accumulating cold temperatures in the first heat exchanger 105 to restore them in the second heat exchanger 125. This circuit 120 thus comprises, along the flow of intermediate refrigerant fluid, at least the two exchangers, 105 and 125 as well as a means 130 for compressing the intermediate refrigerant fluid coming from the second heat exchanger 125.

This compression means 130 is, for example, a pump, preferably centrifugal. In variants, the compression means 130 is a turbocharger (“turbocompressor”), a mechanical or reciprocating compressor.

In preferred embodiments, the compression means 130 is configured to compress the intermediate refrigerant fluid 110 to a pressure of 3 bara. The optimal operating conditions of the present invention in the context of the use of an n-pentane are encountered for the defined parameters such as:

Table 1 If the flow rate of liquid intermediate refrigerant fluid (defined by the ratio kgc5/kgi_H2, because it is relative and proportional to the quantity of H2 to be liquefied) is too low, there is a risk of crystallization of the liquid in the second heat exchanger 125 in due to excessive oxygen cooling. If the flow rate of liquid intermediate coolant 110 is too high, this fluid 110 will not be cooled to a sufficiently low temperature to sufficiently cool the fluids during the cooling of the hydrogen.

If the pressure of the intermediate refrigerant fluid 110 is too low, there is a risk that the fluid will no longer circulate, since it does not sufficiently compensate for the pressure drops induced by the flow in the circuit 120. In embodiments, the streams parameter values are:

Table 2

In preferred embodiments, such as that shown in FIG. 1, the second heat exchanger 125 is configured to cool the target fluid flow 101 with, in addition to the intermediate refrigerant fluid 110, a flow of refrigerant fluid 135, the device comprising a closed circuit 140 of refrigerant fluid, this circuit comprising:

- a means 145 for compressing the low-pressure refrigerant fluid at the outlet of the second heat exchanger 125 to form a high-pressure refrigerant fluid,

- a means 150 for inserting the high-pressure refrigerant fluid into the second heat exchanger,

- a means 155 for expanding the high-pressure refrigerant fluid to form a low-pressure refrigerant fluid,

- a third heat exchanger 160 configured to cool the flow of the target fluid by heat exchange with the coolant at low pressure and

- A means 165 for inserting the low pressure refrigerant fluid into the second heat exchanger.

The refrigerant fluid 135 can be of any type capable of accumulating cold temperatures in order to restore them to the target fluid flow 101. Preferably, this refrigerant fluid 135 comprises at least partially nitrogen. Preferably, this refrigerant fluid 135 comprises at least 75% nitrogen. Preferably, this refrigerant fluid 135 consists entirely (except for impurities) of nitrogen.

In variants, the refrigerant 135 is mainly:

- argon,

- a mixture of nitrogen and argon or - a mixture of hydrocarbons and nitrogen.

In variants, the refrigerant fluid 135 is a mixture of fluid mainly comprising one or more compounds from among methane, ethane, propane, butane, pentane and their isomers.

The purpose of the closed circuit 140 is not to release refrigerant fluid into the atmosphere and its purpose is for the refrigerant fluid 135 to accumulate cold temperatures and restore them in the second exchanger 125 and, after expansion by the means 155 expansion, this coolant 135 participates in the cooling of the target fluid 101 in the third, and optionally fourth, exchangers, 160 and/or 180.

After exchange between the low-pressure intermediate refrigerant fluid 110 and the expanded oxygen 115, the refrigerant fluid 135 is compressed by the compression means 145.

The compression means 145 is, for example, a turbocharger, a mechanical or reciprocating compressor. In variants, the compression means 145 is a pump, preferably centrifugal. Optionally, several compressors or pumps are positioned in series to form the means 145 of compression.

In preferred embodiments, the compression means 145 is configured to compress the refrigerant fluid 135 from 1.1 bara to 50 bara.

In preferred embodiments, the mass flow ratio in the closed circuit 140 is 18 kgN2/kgi_H2.

The compressed refrigerant fluid 135 (known as “high pressure”) is then reinjected into the second heat exchanger 125 via the insertion means 150. This insertion means 150 is, for example, a pipe configured to connect the output of the compression means 145 and the second heat exchanger 125.

In preferred embodiments, the second heat exchanger 125 is configured to lower the temperature of the compressed refrigerant fluid 135 to 200 K (-73° C.).

Downstream of the second passage in the second heat exchanger 125, the high-pressure refrigerant fluid 135 is expanded via the means 155 of expansion. This expansion means 155 is, for example, an expansion turbine, an expansion valve or a turboexpander. In preferred embodiments, the expansion means 155 is configured to lower the pressure of the refrigerant fluid 135 from 50 bara to 1.1 bara, resulting in a lowering of the temperature of the refrigerant fluid 135 to 78.06 K.

Once expanded to form the low-pressure refrigerant fluid 135, this fluid is injected into the third heat exchanger 160 via the insertion means 165. This means 165 of insertion is, for example, a dedicated tube configured to connect the output of the means 155 of expansion to the third exchanger 160 of heat.

In embodiments, such as that shown in Figure 1, the device 100 further comprises a fourth heat exchanger 180 configured to cool the fluid 101 target. This fourth heat exchanger 180 is positioned downstream along the fluid circuit 101 entering the device through the inlet 1025. In such embodiments, the insertion means 165 can be configured to inject the refrigerant fluid 135 at low pressure in the fourth exchanger 180, the refrigerant fluid 135 from the fourth exchanger 180 then being injected into the third exchanger 160 before being injected into the second exchanger 125.

In preferred embodiments, the fourth exchanger 180 is configured to perform a catalytic conversion from a target fluid flow 101 having a temperature below 100 K to produce a fluid flow 101 having a temperature of around 80 K.

Not shown variants of the present invention may consist of:

- add additional compression means 130,

- moving the position of the compression means 130 in the circuit 120 of fluid 110 intermediate refrigerant,

- add intermediate exchangers, similar to the first heat exchanger 105,

- Add additional compression means 145;

- modify the number of interchanges among the second, third and fourth interchanges, 125, 160 and 180 and/or

- carry out all or part of the cooling (catalysis) in an absorption column.

FIG. 2 schematically shows a particular embodiment of the method 200 which is the subject of the present invention. This method 200 for cooling a flow of a target fluid comprises: - a first step 205 of heat exchange to cool an intermediate refrigerant fluid by heat exchange with an expanded flow of oxygen,

- an intermediate stage 210 of circulation in a closed circuit of the intermediate refrigerant fluid from the first stage of heat exchange to a second stage of heat exchange,

- a step 215 of compression of the intermediate refrigerant fluid during the intermediate step 210 of circulation in a closed circuit and

- the second stage 220 of heat exchange to cool the flow of the target fluid by heat exchange with the intermediate refrigerant fluid cooled during the first stage of heat exchange, the intermediate refrigerant fluid being configured to remain in the state liquid or supercritical at least during the performance of the compression step.

These steps are described mutatis mutandis with regard to FIG. 1 .

It is also understood that the present invention is aimed at the use of a flow mainly of n-pentane in a supercritical or liquid state in a closed circuit to mainly cool a body by accumulation of cold temperatures during the heat exchange between a flow mainly of n -pentane compressed and a flow mainly of oxygen.

In embodiments, the body is predominantly hydrogen flux.

In embodiments, the body is predominantly a solid body.

Thus, as is understood, unlike the solutions implemented hitherto, the present invention implements an intermediate refrigeration loop consisting of a liquid fluid which recovers the cooling power of the expanded oxygen directly at the outlet of the electrolyser. Thus, the present invention separates units using oxygen from units using hydrogen. The present invention benefits from at least two main advantages over existing solutions:

- The present invention allows the replacement of compressors compensating pressure drops by centrifugal pumps whose cost in capital and energy is much lower;

- the present invention makes it possible to increase the refrigeration power of the oxygen, because it is relaxed over a wider range of pressures. Finally, a last more situational benefit can be cited: compared to existing solutions using an inert gas such as neon, the present invention allows the reduction of the purchase cost of the intermediate coolant, the liquids envisaged being less expensive. The present invention is of interest in the cases of production of liquid hydrogen juxtaposed with the production of hydrogen by electrolysis of water and where the recovery of oxygen is not profitable because of difficulty linked to its conditioning and /or its sale on the markets. This last condition seems to be met in particular, because the oxygen is most often simply released into the atmosphere.

The present invention is also of interest in the case of production of liquid e-methane from carbon dioxide and hydrogen produced by electrolysis of water where the recovery of oxygen is not profitable for the same reasons. Furthermore, the present invention has the advantage of reducing electricity consumption, which proves to be an asset revealing two trends:

- the greater the capacity, the more the present invention is interesting and

- the higher the cost of purchasing electricity, the more attractive the present invention.

Claims

1. Device (100) for cooling a flow (101) of a target fluid mainly comprising dihydrogen, characterized in that it comprises:

- a first heat exchanger (105) configured to cool an intermediate refrigerant fluid (110) by heat exchange with an expanded flow of oxygen (115),

- an intermediate closed circuit (120) for transporting the intermediate refrigerant fluid from the first heat exchanger to a second heat exchanger (125),

- a means (130) for compressing the intermediate refrigerant fluid along the intermediate closed circuit,

- the intermediate refrigerant, configured to remain in the liquid or supercritical state at least when passing through the compression means and

- the second heat exchanger configured to cool the flow of the target fluid by heat exchange with the intermediate refrigerant fluid cooled in the first heat exchanger.

2. Device (100) according to claim 1, wherein the intermediate refrigerant fluid (110) is mainly:

- an n-pentane,

- an i-butane,

- an n-hexane,

- an n-heptane,

- an n-octane,

- a 2-methylpentane,

- a 2,2-dimethilbutane,

- acetone,

- ether,

- methanol,

- an n-butane or

- ammonia.

3. Device (100) according to one of claims 1 or 2, wherein the second heat exchanger (125) is configured to cool the flow of fluid (101) target with, in addition to the fluid (110) intermediate refrigerant, a flow of refrigerant fluid (135), the device comprising a closed circuit (140) of refrigerant fluid, this circuit comprising:

- a means (145) for compressing the low-pressure refrigerant fluid at the outlet of the second exchanger (125) to form a high-pressure refrigerant fluid,

- a means (150) for inserting the high pressure refrigerant fluid into the second heat exchanger,

- a means (155) for expanding the high-pressure refrigerant fluid to form a low-pressure refrigerant fluid,

- a third heat exchanger (160) configured to cool the flow of the target fluid by heat exchange with the refrigerant at low pressure and

- a means (165) for inserting the low-pressure refrigerant fluid into the second heat exchanger.

4. Device (100) according to claim 3, which comprises a fourth heat exchanger (180) configured to cool the flow of the target fluid (101) by heat exchange with the fluid (135) coolant at low pressure from the means (155 ) for expanding the high-pressure refrigerant fluid, the means (165) for inserting the low-pressure refrigerant fluid into the second heat exchanger (160) being configured to insert the flow of low-pressure refrigerant fluid from the fourth heat exchanger heat.

5. Device (100) according to one of claims 3 or 4, comprising the refrigerant fluid (135), in which the refrigerant fluid is mainly:

- nitrogen,

- argon,

- a mixture of nitrogen and argon or

- a mixture of hydrocarbons and nitrogen.

6. Device (100) according to one of claims 1 to 5, which comprises means (170) for expanding the dioxygen upstream of the first heat exchanger (105).

7. Device (100) according to claim 6, which comprises means (175) for electrolysis of water, configured to produce dioxygen and dihydrogen, the dioxygen produced being supplied to the means (170) for expanding the dioxygen.

8. Device (100) according to claim 7, which comprises means (1025) for injecting dihydrogen from the water electrolysis means into the second heat exchanger (125).

9. Method (200) for cooling a flow of a target fluid mainly comprising dihydrogen, characterized in that it comprises:

- a first heat exchange step (205) for cooling an intermediate refrigerant fluid by heat exchange with an expanded flow of oxygen,

- an intermediate stage (210) of circulation in a closed circuit of the intermediate refrigerant fluid from the first stage of heat exchange to a second stage of heat exchange,

- a stage of (215) compression of the intermediate refrigerant fluid during the intermediate stage of circulation in a closed circuit and

- the second stage (220) of heat exchange for cooling the flow of the target fluid by heat exchange with the intermediate refrigerant fluid cooled during the first stage of heat exchange, the intermediate refrigerant being configured to remain at the liquid or supercritical state at least during the performance of the compression step.