Patent Application
20250207851
The present invention relates to a method and to an apparatus for cooling hydrogen.
It is known to optimize a method for cooling hydrogen by recovering cold energy from the vaporization of liquefied natural gas (LNG).
It is known to liquefy hydrogen in two steps:
The present invention proposes a solution for the first step of precooling the hydrogen using the cold energy of a flow of liquefied natural gas that is vaporized.
In certain embodiments, the method uses a cycle to transfer the heat of vaporization of the liquefied natural gas to the hydrogen that is cooled, this cycle comprising a compressor with an inlet temperature preferably lower than −90° C. and optionally an expansion turbine.
“Large scale hydrogen liquefaction in combination with LNG re-gasification” by Kündig et al., 16th World Hydrogen Energy Conference, 2006, describes a method according to the preamble of claim 1.
According to one subject of the invention, a method for cooling hydrogen is provided, wherein
iii) a flow of gaseous hydrogen is cooled in the second heat exchanger without condensing:
iv) a gaseous flow derived from the intermediate fluid cooled in step a) and/or b) is heated in the second heat exchanger up to a temperature of between −150° C. and −90° C., is withdrawn from the second heat exchanger at this temperature and compressed in a compressor with an inlet temperature of between-150° C. and −90° C. and at least one part of the compressed intermediate fluid is cooled first in the first heat exchanger and then heated from a temperature of at most −110° C.; and
According to other optional aspects of the invention:
According to another subject of the invention, an apparatus for cooling hydrogen is provided, comprising a first heat exchanger, a second heat exchanger, a compressor, optionally a turbine, means for sending either liquefied natural gas or vaporized natural gas, the vaporized natural gas being at a temperature lower than-50° C., to be heated up to a temperature higher than 0° C. by indirect heat exchange in the first heat exchanger, means for sending a flow of intermediate fluid at a pressure of between 3 and 70 bar abs if the intermediate fluid is not nitrogen and between 3 and 25 bar if the intermediate fluid is nitrogen to be cooled in the first heat exchanger down to a temperature higher than or equal to −145° C., means for sending the flow of intermediate fluid at a temperature higher than or equal to −145° C. to be cooled
The apparatus may comprise a phase separator for separating a fluid coming from the turbine, the gaseous flow being the overhead gas and/or the vaporized liquid from the separator.
According to another subject of the invention, an apparatus for liquefying hydrogen is provided, comprising an apparatus for cooling hydrogen as described above and means for liquefying the hydrogen cooled in the cooling apparatus,
The use of an intermediate fluid makes it possible to better control the integration by differentiating the hydrogen and LNG networks.
Thus the risk of leakage to the H2 is reduced.
It is possible to modify the parameters (pressure, flow rate) of the intermediate fluid cycle so as to mitigate the fluctuations in the LNG.
Precise regulation of the output conditions of the vaporized LNG/of the cooled H2 in an independent manner is possible.
It is possible to make profitable use of cold from an LNG terminal remote from the H2 liquefaction unit via an intermediate fluid (so as to avoid importing/exporting natural gas from the LNG terminal).
The vaporization of the LNG is done in a single exchanger and the intermediate fluid distributes the cold toward the various consumers.
The intermediate cycle makes it possible to produce a cold fluid with a lower temperature than the LNG.
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.
A dedicated heat exchanger E1 serves to recover the cold energy from the liquefied natural gas 1 at −150° C. using an intermediate fluid that is cooled by the liquid 1 in the exchanger E1. The exchanger E1 may be a brazed plate and fin exchanger made of stainless steel or of steel. Otherwise, the exchanger E1 may be a shell and tube exchanger.
The liquid 1 is heated, for example up to 15° C., and optionally vaporized so as to cool the fluid 5 down to a temperature lower than −50° C., preferably lower than −120° C. In the example it is cooled down to −140° C.
The gas 1 enters at the cold end of the exchanger E1 and leaves at the hot end as fluid 3.
In the example, the fluid 5 is nitrogen. It may, for example, be natural gas or methane. Preferably, the fluid 5 is inert. The fluid 5 is preferably at a pressure of between 3 and 70 bar abs if the intermediate fluid is not nitrogen and between 3 and 25 bar if the intermediate fluid is nitrogen.
The nitrogen 13 leaves the exchanger E2 at a temperature lower than −90° C., for example at −120° C., or even between −150° C. and −110° C., and is compressed in a compressor C, for example a centrifugal compressor, to approximately 20 bar. Then the nitrogen at 20 bar is optionally divided into two parts 15, 17, the part 17 not necessarily being present. The part 17 may be cooled partially in the exchanger E1 and then is sent to an element to be cooled 31. Thus the heated part 19 is sent to the hot end of the exchanger E1. The part 15, 21 is sent at 20° C. to the hot end of the exchanger E1 and is cooled there down to −140° C. forming a gas 5 that is sent to the exchanger E2 at a temperature of −140° C., therefore colder than the temperature at which the gas 13 is withdrawn from the exchanger E2. The gas 5 is heated in the exchanger E2 up to 20° C. and then is cooled against the LNG in the exchanger E1. The cooled gas at −140° C. is sent to be cooled, in this example first by passing into the exchanger E2 and then by expansion in a turbine T having an inlet temperature lower than −100° C., for example −120° C. The expanded fluid 7 at 1.5 bar in the turbine T is two-phase and is sent to a phase separator where it forms a liquid 9 and a gas 11. The liquid is vaporized in a heat exchanger E3 and joins the gas 11 so as to be heated in the exchanger E2 constituting the flow 13 to be sent to the cold compressor C. The flow 13 may be constituted by the vaporized liquid 9 and/or the gas 11.
Thus the nitrogen, or another fluid, for example helium or a mixed refrigerant, circulates in a closed cycle, taking cold energy from the LNG.
The gaseous hydrogen 23 at ambient temperature, for example 20° C., enters at the hot end of the heat exchanger E2 that it passes through from one end to the other so as to be cooled down to −180° C. It is then cooled in the heat exchanger E3 against the liquid of the phase separator so as to form gaseous hydrogen 25 at −190° C.
The hydrogen 25 is then cooled and liquefied in another heat exchanger in a known manner. A cycle of hydrogen, helium or mixed refrigerants optionally including rare gases provides the necessary cold energy.
Thus the LNG provides at least a part of the cold energy necessary for the precooling of the gaseous hydrogen down to −190° C. This fraction may be at least 50%, at least 75%, or at least 99% of the cold energy necessary for the cooling of the gaseous hydrogen down to −190° C. The LNG may even provide all the necessary cold energy apart from that coming from the turbine T.
During start-up of the apparatus, the LNG may be vaporized in an independent vaporizer, for example of the “Open Rack Vaporizer” type, by heat exchange with water, optionally seawater. This vaporizer comprises a series of vertical tubes in which the LNG that is vaporized circulates, the water running over the outside of the tubes. Other types of exchanger can obviously be envisaged.
The method may also provide cold to another element 31, cooled by the cycle. In the figure, it can be seen that a part 17 of the gas compressed in the compressor C is cooled in the heat exchanger down to an intermediate temperature, in this case −50° C., is withdrawn from the exchanger in a central zone of the heat exchanger and serves to cool the element 31 by being itself heated to form the gas 19 that joins the flow 15 compressed in the compressor C so as to form the flow 21 that enters the exchanger E1 at 20° C. As the pressure drops for the flow 18, 19 are limited, a small expansion of the flow 15 in a valve will be sufficient to allow the flows 15, 19 to mix.
The element 31 may for example be a liquefier for another gas or an apparatus for separation by distillation and/or partial condensation at a temperature lower than 0° C., for example a carbon dioxide liquefier.
If the fraction 17 is present but the element 31 is not in operation, a heater, for example an electric heater or a heat exchanger heated with hot water, will serve to heat the fraction 17 so as to form the flow 19.
The natural gas 3 produced may be sent to a hydrocarbon conversion unit to be converted and/or as fuel. The unit may be of the POX, ATR or SMR type.
The hydrogen to be liquefied can obviously come from this unit.
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.
| Number | Date | Country | Kind |
|---|---|---|---|
| FR2202427 | Mar 2022 | FR | national |
| FR2204918 | May 2022 | FR | national |
This application is a § 371 of International PCT Application PCT/EP2023/051625, filed Jan. 24, 2023, which claims the benefit of FR2202427, filed Mar. 18, 2022, and FR 2204918, filed May 23, 2022, all of which are herein incorporated by reference in their entireties.
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/EP2023/051625 | 1/24/2023 | WO |
