Cooling system and method

Abstract

The invention relates to a cryogenic fluid cooling installation comprising, a first circuit (7) of fluid to be cooled, for example liquid nitrogen and / or liquid oxygen, a cryogenic refrigerator (6) with a cycle circuit (16), at least one heat exchanger (5) ensuring heat exchange with the first circuit (7) of fluid to be cooled and the cycle circuit (16) of the refrigerator (6), the installation comprising a second circuit (8) of fluid to be liquefied, for example gaseous nitrogen and / or gaseous oxygen, the second circuit (8) of fluid being in heat exchange with the cycle circuit (16) of the refrigerator (6) in at least one heat exchanger (2, 3, 4, 5) of the installation,the installation (1) being configured to be switchable in a first cooling operating mode in which the installation cools the first fluid circuit (7) to cool a liquefied fluid to preferably generate a quasi-isothermal transformation of said fluid, and a second liquefaction operating mode in which the installation (1) cools the second fluid circuit (8) for the purpose of liquefying a gas stream.

Description

[0001] The invention relates to a cooling installation and method.

[0002] The invention relates more particularly to a cryogenic fluid cooling installation comprising, a first circuit of fluid to be cooled, for example liquid nitrogen and / or liquid oxygen, a cryogenic refrigerator with a cycle circuit, at least one heat exchanger ensuring heat exchange with the first circuit of fluid to be cooled and the cycle circuit of the refrigerator, the installation comprising a second circuit of fluid to be liquefied, for example gaseous nitrogen and / or gaseous oxygen, the second fluid circuit being in heat exchange with the cycle circuit of the refrigerator in at least one heat exchanger of the installation.

[0003] The invention can be advantageously applied to an installation requiring cryogenic fluids for the thermalization of lines at cryogenic temperature, for example cryogenic fluid pipelines for superconductivity applications (cables).

[0004] The invention allows in particular the liquefaction of nitrogen and / or oxygen with possible mixing if needed for the application of an end customer with high temperature superconductivity.

[0005] The gases to be liquefied can be mixed upstream or downstream of the liquefier and the cold fluid can be used for the transport of electricity in high current density by maintaining in a superconducting state an electricity transport cable.

[0006] The invention makes it possible to replace, at least partially, the delivery of cryogenic fluid by truck by producing the necessary cold at the user site. Another alternative would be the temporary on-site installation of a nitrogen and / or oxygen separation and liquefaction unit (ASU), which is not very cost-effective considering the typical usage time and quantities required. Installations with tens of kilometers of cable require several thousand tons of cryogenic fluid.

[0007] The installation may include a unit maintained in superconductivity at sea over long distances for electricity transmission.

[0008] One aim of the present invention is to overcome all or part of the disadvantages of the prior art noted above.

[0009] To this end, the installation according to the invention, which also conforms to the generic definition given in the preamble above, is essentially characterized in that it is configured to be switchable in a first cooling operating mode in which the installation cools the first fluid circuit to cool a liquefied fluid to preferably generate a quasi-isothermal transformation of said fluid, and a second liquefaction operating mode in which the installation cools the second fluid circuit for the purpose of liquefying a gas flow.

[0010] Furthermore, embodiments of the invention may include one or more of the following characteristics: The installation includes a source of gas to be liquefied connected to the second fluid circuit, for example a source of gaseous nitrogen and / or oxygen; the installation includes a source of liquid cryogenic fluid connected to the first fluid circuit, for example a source of liquid nitrogen and / or liquid hydrogen; the installation includes several heat exchangers in series ensuring heat exchange between the second fluid circuit and the cycle circuit and at least one heat exchanger in heat exchange with the cycle circuit and comprising separate passages for the first and second fluid circuits within the same heat exchange body; the refrigerator is of the cycle circuit type subjecting a cycle gas to a thermodynamic cycle with compression in at least one compressor of the cycle circuit driven by a motor and expansion in at least one turbine.The refrigerator being configured to recover work from the turbine(s) to the compressor(s), the motor being of the variable-speed type controllable to control the cooling power produced, the installation includes a network of superconducting cable conduits cooled by a flow of cryogenic liquid such as nitrogen and / or oxygen, said flow of cryogenic liquid being configured to pass through the first fluid circuit for the purpose of its cooling.

[0011] The invention also relates to a method for cooling such an installation, the method comprising a step of cooling a flow of cryogenic liquid from the first fluid circuit to a temperature below the saturation temperature of the fluid.

[0012] Depending on other possible characteristics: The process includes, prior to the step of cooling a cryogenic fluid stream from the first fluid circuit, a step of liquefying a gas stream in the second fluid circuit, the liquefied gas being transferred into the network of superconducting cable conduits, the process includes a step of supplying the second fluid circuit with a mixture of gas to be liquefied, for example nitrogen gas and oxygen gas, the process including a step of liquefying said mixture.

[0013] The invention may also relate to any alternative device or method comprising any combination of the above or below features within the scope of the claims. Other features and advantages will become apparent from the following description, given with reference to the figures in which: Brief description of the figures

[0014] The invention will be better understood upon reading the following description, given solely by way of example and made with reference to the accompanying drawings in which: [ Fig. 1 ] is a schematic and partial view illustrating an example of the structure and operation of an installation according to the invention. Detailed description

[0015] In all the figures, the same references refer to the same elements.

[0016] In this detailed description, the following embodiments are examples. Although the description refers to one or more embodiments, this does not mean that the features apply only to a single embodiment. Simple features from different embodiments can also be combined and / or interchanged to provide other embodiments.

[0017] As illustrated, the installation 1 is configured to provide cooling for a flow of cryogenic fluid. This installation 1 includes a first circuit 7 of the fluid to be cooled, for example liquid nitrogen and / or liquid oxygen, a cryogenic refrigerator 6 with a cycle circuit 16 and at least one heat exchanger 5 providing heat exchange between the first circuit 7 of the fluid to be cooled and the cycle circuit 16 of the refrigerator 6.

[0018] Installation 1 further includes a second circuit 8 of fluid to be liquefied, for example, gaseous nitrogen and / or gaseous oxygen. This second fluid circuit 8 also exchanges heat with the refrigerator cycle circuit 16 via at least one heat exchanger 2, 3, 4, 5 of installation 1.

[0019] Installation 1 is configured to be switchable into a first cooling operating mode in which the installation cools the first fluid circuit 7 to cool a liquefied fluid to preferably generate a quasi-isothermal transformation of said fluid, and a second liquefaction operating mode in which the installation 1 cools the second fluid circuit 8 for the purpose of liquefying a gas stream.

[0020] That is to say, installation 1 allows for the subcooling of fluids such as liquid nitrogen, liquid oxygen or a mixture of these two constituents to provide cooling power to, for example, maintain an electricity transmission cable in a superconducting state.

[0021] Similarly, installation 1 allows the liquefaction of the previously mentioned gases, for example for cooling cryogenic line(s).

[0022] For this purpose, the first circuit 7, supplying the subcooled liquid, can be connected to a unit comprising cables maintained in a superconducting state. The second fluid circuit 8 can be connected to the unit to provide cooling (cooling of at least a part of the unit).

[0023] For example, the installation includes a network 11 of superconducting cable conduits cooled by a flow of cryogenic liquid such as nitrogen and / or oxygen, and this flow of cryogenic liquid is configured to pass through the first fluid circuit 7 for the purpose of its cooling (subcooling). In particular, this flow of cryogenic liquid from the first fluid circuit 7 can be cooled to a temperature below the saturation temperature of said fluid.

[0024] Very large charges of cryogenic liquid may be required to cool such units (for example, circuits of several tens of kilometers of super-submarine cables). Lesser requirements may be needed to maintain the unit's temperature.

[0025] Prior to a (sub)cooling stage of a cryogenic fluid stream in the first fluid circuit 7, the installation can perform a liquefaction stage of a gas stream in the second fluid circuit 8. This liquefied gas can be transferred through the network 11 of superconducting cable conduits. Installation 1 is advantageously sized for two cases, given that the cooling use case involves a significant logistical undertaking for a very rare occurrence.

[0026] The gas supply (nitrogen and oxygen for example) can be achieved by a gas separation unit (ASU or preferably of the "APSA" type, and / or a generator of relatively pure nitrogen and / or O2).

[0027] The installation is configured to ensure cooling of this gas or these gases from a temperature significantly higher than the liquefaction temperature of said gas to be liquefied. Thus, as schematically shown, the installation 1 may include a source 9 of gas to be liquefied connected to an upstream end of the second fluid circuit 8, for example a source of nitrogen and / or oxygen gas.

[0028] Similarly, the installation may include a source 10 of liquid cryogenic fluid connected to an upstream end of the first fluid circuit 7, for example a source of liquid nitrogen and / or liquid hydrogen.

[0029] As illustrated, the installation 1 may include several heat exchangers 2, 3, 4, 5 in series ensuring heat exchange between the second fluid circuit 8 and the cycle circuit 16 and at least one heat exchanger 5 in heat exchange with the cycle circuit 16 and including separate respective passages for the first fluid circuit 7 and the second fluid circuit 8 within the same heat exchange body.

[0030] The refrigerator 6 is preferably of the cycle circuit type 16 subjecting a cycle gas to a thermodynamic cycle with compression in at least one compressor 26 of the cycle circuit driven by a motor and expansion in at least one turbine 36.

[0031] Preferably, the refrigerator 6 is configured to recover work from the or at least one turbine 36 to the or at least one compressor 26 and, preferably also, the or at least part of the drive motors of the compressor(s) is of the controllable variable speed type to control the cooling power produced.

[0032] Refrigerator 6, for example, is of the TurboBrayton cycle type and has two main operating modes (cooling with liquefaction or sub-cooling).

[0033] This is possible with this type of refrigerator and especially in the case of motors controlled according to VFD (variable frequency) technology.

[0034] To achieve these two modes of operation, the heat exchanger(s) may have dedicated passages respectively for cooling or subcooling and / or may use identical passages of the heat exchangers.

[0035] In the case where the heat exchanger(s) use(s) the same passages for both modes of operation, the exchanger is configured (material and dimensions) to support the two corresponding levels of thermal gradients.

[0036] In the illustrated, non-limiting example, the refrigerator 6 has four compression stages 26 in series (centrifugal compressors) and two centripetal expansion stages 36 in series. In the case of an offshore installation, a first refrigerator may be provided onshore to liquefy the fluid intended for cooling submarine cables, while at least a second, remote refrigerator may be provided offshore to cool, if necessary, the flow that has exchanged with the submarine cables.

[0037] The first and second refrigerators can operate under different operating conditions despite having an identical structure (to adapt to different thermal loads and conditions).

Claims

1. A cryogenic fluid cooling system comprising a first circuit (7) of the fluid to be cooled, for example liquid nitrogen and / or liquid oxygen, a cryogenic refrigerator (6) with a cycle circuit (16), at least one heat exchanger (5) providing heat exchange with the first circuit (7) of the fluid to be cooled and the cycle circuit (16) of the refrigerator (6), the system comprising a second circuit (8) of the fluid to be liquefied, for example gaseous nitrogen and / or gaseous oxygen, the second fluid circuit (8) being in heat exchange with the cycle circuit (16) of the refrigerator (6) in at least one heat exchanger (2, 3, 4, 5) of the system, the system comprising a source (9) of the gas to be liquefied connected to the second fluid circuit (8), for example a source of gaseous nitrogen and / or oxygen, and a source (10) of liquid cryogenic fluid connected to the first circuit (7) of fluid,for example a source of liquid nitrogen and / or liquid hydrogen, the installation further comprising a network (11) of superconducting cable conduits cooled by a flow of cryogenic liquid such as nitrogen and / or oxygen, said flow of cryogenic liquid being configured to pass through the first fluid circuit (7) for the purpose of its cooling, the installation comprising several heat exchangers (2, 3, 4, 5) in series ensuring heat exchange between the second fluid circuit (8) and the cycle circuit (16) and at least one heat exchanger (5) in heat exchange with the cycle circuit (16) and comprising separate passages for the first fluid circuit (7) and the second fluid circuit (8) within the same heat exchange body,the installation (1) being configured to be switchable in a first cooling operating mode in which the installation cools the first fluid circuit (7) to cool a liquefied fluid, or in a second liquefaction operating mode in which the installation (1) cools the second fluid circuit (8) for the purpose of liquefying a gas stream.

2. Installation according to claim 1, characterized in that the refrigerator (6) is of the cycle circuit type subjecting a cycle gas to a thermodynamic cycle with compression in at least one compressor of the cycle circuit driven by a motor and expansion in at least one turbine, the refrigerator being configured to recover work from the or at least one of the turbines to the or at least one compressor, the motor being of the controllable variable speed type to control the cooling power produced.

3. A method for cooling an installation according to claim 1 or 2, characterized in that it includes a step of cooling a cryogenic liquid stream from the first circuit (7) of fluid to a temperature below the saturation temperature of the fluid.

4. Method according to claim 3, characterized in that Prior to the cooling step of a cryogenic fluid stream in the first fluid circuit (7), it includes a liquefaction step of a gas stream in the second fluid circuit (8), the liquefied gas being transferred into the network (11) of superconducting cable conduits.

5. A method according to any one of claims 3 or 4, characterized in that it includes a step of supplying to the second fluid circuit (8) a mixture of gas to be liquefied, for example nitrogen gas and oxygen gas, the process including a step of liquefying said mixture.

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