WO2021239293A1

WO2021239293A1 - Method and device for cryogenic cooling

Info

Publication number: WO2021239293A1
Application number: PCT/EP2021/057695
Authority: WO
Inventors: Guillaume DELAUTRE; Loïc Jeunesse; Golo Zick; Thomas Gates; James Timothy MACHERAS
Original assignee: L'air Liquide Societe Anonyme Pour L'etude Et L'exploitation Des Procedes Georges Claude; Air Liquide Advanced Technologies U.S. Llc
Priority date: 2020-05-27
Filing date: 2021-03-25
Publication date: 2021-12-02
Also published as: FR3110961B1; US20230194195A1; FR3110961A1; EP4158270A1

Abstract

Method for cryogenic cooling of a first fluid (2) by heat exchange with at least one second fluid (3) in a heat exchanger (1), the first fluid (2) and/or the second fluid (3) being at a temperature between -100°C and -273°C, characterized in that the heat exchanger (1) is of the type with polymer microtubes, i.e. comprising a plurality of microtubes (4) made of polymer and having a diameter of between 0.1 mm and 1 cm, one of the first (2) and second (3) fluids being circulated inside said microtubes (4) whilst the other fluid is circulated around said microtubes (4).

Description

Cryogenic cooling method and device

The invention relates to a method and a device for cryogenic cooling.

The invention relates more particularly to a method for cryogenic cooling of a first fluid by heat exchange with at least one second fluid in a heat exchanger, the first fluid and / or the second fluid being at a temperature between -100 ° C. and -273 ° C.

The structure of cryogenic heat exchangers is generally bulky, expensive and massive. For example, plate heat exchangers or aluminum or metal tube exchangers are known. This type of exchanger is thus ill-suited for certain applications where mass or volume are critical (on board floating or flying vehicles, for example). Other less massive technologies are known (for example, shell-tube type exchangers with polymer tubes) but are not suitable for applications in cryogenic temperature ranges (below minus 100 ° C for example) because these exchangers are weakened at these temperatures and are not able to withstand pressure differentials and / or encounter sealing and performance problems.

An aim of the present invention is to overcome all or part of the drawbacks of the prior art noted above.

To this end, the device according to the invention, moreover in accordance with the generic definition given in the preamble above, is essentially characterized in that the heat exchanger is of the type with polymer microtubes. that is to say comprising a plurality of polymer microtubes and having a diameter between and 0.1mm and 1cm, one of the first and second fluids being circulated inside said micro-tubes while the other fluid is circulated around said micro-tubes.

Furthermore, embodiments of the invention may include one or more of the following characteristics: the microtubes are made of at least one of the following materials: polyetheretherketone (PEEK),

Polytetrafluoroethylene (PTFE), Polyetherimide, polyimide (s), polyamide (s), polycarbonate (s) or any other plastic material compatible with use at said low temperatures, the micro-tubes are made of a material comprising a mixture of polyetherimide ( "Ultem") and Peek, the micro-tubes are made of a material having a density between 2700kg / m ³ and 900kg / m ³ and in particular less than 1500kg / m ³ the micro-tubes have a diameter of between between 0.1mm and 5mm, the pressure differential between the pressure of the fluid circulated in the micro-tubes and the pressure of the fluid circulated around the micro-tubes is between 1 bar and 100 bar and in particular between 10 and 50bar, the heat exchanger comprises a housing in which the micro-tubes are arranged, the housing comprising a first inlet communicating with a first end of the micro-tubes, the housing comprising a first outlet communicating with a second e xtrend of the microtubes, the housing also comprising a second inlet and a second outlet communicating with the volume located around the microtubes, the microtubes are arranged in a bundle in a longitudinal direction in the housing, the beams are arranged parallel to the longitudinal direction and are preferably rectilinear, the microtubes are wound in a helix, preferably distributed around a central support mandrel, at least one of the two longitudinal ends of the bundle of microtubes comprises a layer of material rigid such as a thermosetting material ensuring the cohesion of the bundle of microtubes, the housing housing at least one elastic member constrained in the longitudinal direction between a stop formed in the housing and a longitudinal end of the bundle of microtubes, to ensure the maintenance length of the bundle of microtubes while allowing expansion or contraction relative to the housing in the longitudinal direction, the elastic member comprises at least one of: a spring, a helical spring, one or more elastic washers, in particular of Belleville type, the housing comprises an elastic zone in the longitudinal direction such as a bellows, the method ensures heat exchange between more than two fluids, that is to say that distinct portions of the micro tubes and / or of the volume around the micro-tubes accommodate separate flows of fluid (s) for heat exchange in the heat exchanger, cooling is carried out in a pr ocess for refrigeration and / or cryogenic liquefaction of a fluid, the heat exchanger being located in a device for refrigeration and / or cryogenic liquefaction.

The invention also relates to a device for cryogenic cooling of at least one first fluid by heat exchange with at least one second fluid comprising a heat exchanger providing heat exchange between the first fluid and the second fluid, the first and / or the second fluid being at a temperature between -100 ° C and -273 ° C, the heat exchanger being of the polymer microtube type, that is to say comprising a plurality of polymer microtubes and having a diameter of between 0.1mm and 10mm, the heat exchanger comprising inlets and outlets for the first and second fluid ensuring circulation of at least one fluid to inside said micro-tubes and a circulation of the other fluid around said micro-tubes.

Furthermore, according to possible characteristics: the exchanger comprises a working circuit containing a working fluid, the working circuit comprising at least one working gas compressor, at least one heat exchanger for cooling the compressed fluid, at least a working fluid expansion member, at least one heat exchanger for reheating the expanded working fluid, the at least one cooling heat exchanger and / or the at least one reheating heat exchanger is of the micro-type polymer tubes that is to say comprising a plurality of polymer microtubes and having a diameter between and 0.1mm and 10mm, and comprising inlets and outlets for a first flow of working fluid and another fluid having a temperature distinct from the temperature of the first flow of working fluid, to ensure heat exchange between the first flow of working fluid and the other fluid.

The invention may also relate to any alternative device or method comprising any combination of the characteristics above or below within the scope of the claims.

Other features and advantages will become apparent on reading the description below, given with reference to the figures in which:

[Fig. 1] represents a view in longitudinal section, schematic and partial, illustrating a first example of the structure and operation of a cooling heat exchanger according to the invention,

[Fig. 2] represents a view in longitudinal section, schematic and partial, illustrating a second example of the structure and operation of a cooling heat exchanger according to the invention, [Fig. 3] represents a view in longitudinal section, schematic and partial, illustrating a third example of the structure and operation of a cooling heat exchanger according to the invention,

[Fig. 4] shows an enlarged detail of the heat exchanger of [Fig. 3],

[Fig. 5] shows a sectional view of an example of an elastic member that can be used in such a heat exchanger,

[Fig. 6] represents a view in longitudinal section, schematic and partial, illustrating a fourth example of the structure and operation of a cooling heat exchanger according to the invention,

[Fig. 7] represents a schematic and partial view illustrating an example of the structure and operation of a cryogenic refrigeration device which can use a cooling heat exchanger according to the invention,

[Fig. 8] illustrates a view in longitudinal section of another embodiment of such a cooling heat exchanger.

The cryogenic cooling heat exchanger 1 shown schematically in FIG. 1 ensures the cooling of a first fluid 2 by heat exchange with a second fluid 3. For example the first fluid 2 and / or the second fluid 3 is a temperature between -100 ° C and -273 ° C. Although optimal at cryogenic temperatures, the invention can also be used at room temperature or between room temperature and cryogenic temperatures. The heat exchanger 1 is of the polymer microtubes type, that is to say comprising a plurality of polymer microtubes 4 and having a diameter of between 0.1 mm and 1 cm. For example the first 2 fluid is circulated inside said micro-tubes 4 while that the second fluid 3 is circulated around said micro-tubes 4. The micro-tubes 4 are preferably non-porous.

The micro-tubes 4 preferably consist of at least one of the following materials: polyetheretherketone (PEEK), Polytetrafluoroethylene (PTFE), Polyetherimide polyimides, polyamides, polycarbonates, for example a mixture of 50% polyetherimide (“Ultem”) and 50% of Peek and in particular any suitable material compatible with cryogenic temperatures. This PEEK / Ultem mixture can be extruded in the form of an amorphous material whose glass transition temperature (Tg, or Tg in English) is about 180 ° C. This mixture, unlike the materials used in the literature, does not require any annealing. In addition, this mixture is essentially non-crystalline, it is quite strong and flexible as it is made. Other crystalline materials cited in the literature would have relatively high coefficients of thermal expansion (CTE), some exceeding 80 ppm / ° C.

Since the heat exchanger must operate over a very wide temperature range, it is essential that the materials of construction have tightly matched coefficients of thermal expansion (CTE). This is necessary so that the various components of the device can expand and contract in unison over the operating temperature range. It is essential that the CTEs be closely aligned to maintain the bond between the tubesheet material and the heat exchange tubes as well as between the tubesheet and the structural support bundle mandrel. All structural components of the module are selected for their closely aligned or closely homogeneous CTEs.

Thus, the coefficient of thermal expansion (CTE) of PEEK is 45, the coefficient of thermal expansion of Ultem is 45 and the coefficient of thermal expansion of the epoxy resin is for example equal to 55. This constituent material is compatible with cryogenic temperatures (up to a few degrees Kelvin for example) and can withstand large pressure differentials (which can for example reach of the order of 100 bar).

The micro-tubes 4 are preferably made of a material having a density less than 2700 kg / m ³ and in particular less ^{than 1500 kg / m 3} and for example between 900 kg / m 3 and 2700 kg / m 3.

The microtubes 4 preferably have a thickness of between 0.01mm and 1mm, in particular 0.05mm. In addition, the microtubes 4 preferably have a diameter of the order of 0.1 to several millimeters, in particular one millimeter.

This allows significant heat exchange between the two fluids while limiting the volume and mass of the heat exchanger. The mechanical resistance to the pressure differential between the parts of the exchanger subjected to a high pressure and the parts subjected to a lower pressure is not affected, on the contrary.

The pressure differential between the pressure of the fluid 2 circulated in the micro-tubes 4 and the pressure of the fluid 3 circulated around the micro-tubes 4 can be between 1 bar and 100 bar and in particular between 10 and 50 bar .

The heat exchanger 1 may comprise a housing 5 in which the micro-tubes 4 are arranged. The housing 5 comprises a first inlet 6 communicating with a first end of the micro-tubes 4 and a first outlet 7 communicating with a second end of the tubes. micro-tubes 4. The housing 5 also comprising a second inlet 8 and a second outlet 9 communicating with the volume located around the micro-tubes. These two input / output pairs define two independent circuits for two fluids. As illustrated, the microtubes 4 can be arranged in a bundle, for example parallel in a longitudinal direction in the housing 5 (and in particular rectilinear or substantially rectilinear), or according to any other geometric configuration.

For example, the micro-tubes 4 can be wound in a helix and for example distributed in an organized manner around a central support mandrel. This helical winding can serve not only to control the packing density of tubes, but also provides a unique mechanism to combat potential dimensional shrinkage of tubes at low temperatures. In devices whose microtubes are oriented in parallel, the shrinkage of the tubes due to thermal contraction can potentially exert a stress on the microtubes 4 which will be transmitted to the tubesheet. This stress can lead to a rupture of the bond between the tube sheet material and the individual tubes or, in extreme cases, failure of the tube sheet or the manifold itself.

The helically wound micro-tubes 4 make it possible to relieve the shrinkage stress by modifying their winding angle in the device. The micro-tubes 4 can therefore not be subjected to an axial tension during their shrinking.

The [Fig. 8] illustrates a view in longitudinal section of a possible embodiment of such a heat exchanger with micro-tubes 4 helically wound around a central mandrel 20. The bundle of coiled micro-tubes 4 can thus form a tubular entity, the two ends of which can be mounted respectively on the axes of two inserts 21, 22 mounted at the ends of the mandrel 20.

The peripheral surface (for example cylindrical) of the bundle of microtubes 4 can be coated with a winding or a protective and / or retaining layer 23. The fluid 2 circulated in the micro-tubes 4 can be admitted for example transversely to an inlet at one longitudinal end of the exchanger and exit at the other longitudinal end, for example via passages 24 opening through the mandrel 20 and exit via a central passage of an insert 22. The cooling fluid can pass it longitudinally around the micro-tubes 4 in a direction opposite to the longitudinal progression of the first fluid 2.

In addition, one and preferably the two longitudinal ends of the bundle of microtubes 4 comprises a layer 13 of rigid material such as a thermosetting (epoxy resin or other) ensuring the cohesion of the bundle of microtubes and resistant to cryogenic temperatures. This rigid zone can in particular be used to ensure a seal between the two fluid circuits (for example via one or more seals 18, in particular O-rings interposed between the housing 5 and the resin layer 13 (as illustrated in [ Fig. 3]).

This mass or layer 13 of solid resinous material bonds the micro-tubes 4 at the ends to prevent the high pressure fluid from communicating with the low pressure fluid when the module is operating. The resin used for this part binds reliably with the material constituting the microtubes 4 and also has a high glass transition temperature Tg (for example of the order of 150 ° C.).

This adhesion between the resin and the micro-tubes 4 is improved by the use of the aforementioned materials constituting the micro-tubes 4. In fact, the PEEK is a crystalline material whose surface is relatively "slippery" because of its low coefficient of friction. Therefore, it is generally difficult to bond it with an adhesive resin. The incorporation of polyetherimide (Ultem) or equivalent as mentioned above in the micro-tube composition 4 produces an amorphous structure. The alloy therefore gives the resin more "bonding" possibilities for better adhesion.

As illustrated in [Fig. 3] or [Fig. 4], the housing 5 can house at least one elastic member 11 constrained in the longitudinal direction between a stop formed in the housing 5 and a longitudinal end of the bundle of microtubes, to ensure the longitudinal retention of the bundle of microtubes while by allowing its expansion or contraction relative to the housing 5 in the longitudinal direction. Thus, a longitudinal end of the bundle of microtubes can be blocked longitudinally while the other can be free longitudinally and held by the elastic member 11. This makes it possible to absorb contractions / expansion of the bundle of microtubes when the bundle is subjected to variations in temperature while maintaining the seal.

As illustrated in [Fig. 3] or [Fig. 4], the elastic member may comprise or be constituted by a spring 11, in particular helical. Of course, one or more stacked elastic washers 12, in particular of the Belleville type, can be envisaged as shown schematically in [FIG. 5].

The first fluid 2 (gas or liquid for example at high pressure between 5 bars and 100 bars) can enter via the inlet 6 (on the left in [Fig. 1]), enter the micro-tubes 4 and exit at the other end via the outlet 7. Simultaneously, the second fluid 3 (gas or liquid for example at low pressure between 1 bar and 99 bar) enters the housing 5 via an inlet (in the upper part of [Fig. 1]). ), circulates around the microtubes 4 and exits via the outlet 9 (in the lower part in [Fig. 1]).

The embodiment of [Fig. 2] differs from that of [Fig. 1] only in that transverse deflectors 19 are provided in the housing 5 to force the second fluid out. meandering around the micro-tubes 4 between the inlet 8 and the outlet 9. This improves the efficiency of the heat exchange.

The housing 5 can be made of a composite material, of epoxy resin with glass fibers, polymer, metal or any other suitable material and in particular the same material as that constituting the micro-tubes 4. This minimizes the contraction differentials between the housing 5. and microtubes 4.

The pressure differential between the pressure of the fluid circulating in the micro-tubes 4 (for example at high pressure) and the pressure of the fluid circulating around the micro-tubes (for example at low pressure) can be of the order of a few bars or several tens of bar, for example of the order of one hundred bar. As illustrated in [Fig. 6], the housing 5 may include an elastic zone 14 in the longitudinal direction such as a bellows to absorb variations in dimensions due to changes in temperature.

Such a cryogenic heat exchanger 11 is particularly efficient, compact and lightweight compared to known cryogenic exchangers. Such an exchanger can be used in particular as a cooling exchanger in a refrigeration and / or liquefaction device.

The heat exchanger 1 can in particular be used in a liquefier cooler of the “Turbo Brayton” type.

The [Fig. 7] illustrates an example of a cooling device 10. This comprises a working circuit 15 containing a working fluid (helium and / or hydrogen and / or argon and / or nitrogen and / or any other gas).

The working circuit 15 comprises at least one working gas compressor 16, at least one heat exchanger 1 for cooling the compressed fluid, at least one member 17 for expanding the working fluid, at least one reheating heat exchanger 117 relaxed working fluid. The expansion device may for example comprise at least one from among a turbine, a Joule-Thomson valve, at least one orifice, etc. For example, the at least one cooling heat exchanger 1 and / or the at least one reheating heat exchanger 1 can be a heat exchanger 1 of the aforementioned type with polymer microtubes.

For example, such a heat exchanger 1 can be used in such a device as a countercurrent heat exchanger to heat exchange the working fluid in two distinct states of the cycle.

For example, at one end of heat exchanger 1 (on the right in [Fig. 7]) the temperature of the fluid is reduced in heat exchanger 1 (for example from non-cryogenic ambient temperature to a cryogenic temperature in particular between 130K and 4K) while at another end (on the left in [Fig. 7]) a flow of this fluid is heated (for example from a cryogenic temperature to a non-cryogenic temperature).

Of course, the heat exchanger 1 is not limited to the above examples. So, for example, the heat exchange can be configured to perform heat exchange between more than two fluids (three, four or more). That is to say that distinct portions of the microtubes 4 and / or of the volume around the microtubes 4 can accommodate distinct flows of fluids (different fluids or fluid of the same nature but at different or similar temperatures) for heat exchange in the heat exchanger 1.

Such a heat exchanger 1 can if necessary ensure heat exchange with another fluid (liquid nitrogen for example).

Such a heat exchanger 1 can in particular be used to pre-cool the fluid with a cold heat transfer fluid (liquid nitrogen, or any other fluid).

Such a heat exchanger 1 can also be used for cooling the working fluid at the outlet of a compressor. In this case the working fluid can be put into heat exchange with a heat transfer fluid such as water for example. In this case, the fluids put into heat exchange are not necessarily at cryogenic temperatures and could be replaced by a more conventional heat exchanger, but the interest of the aforementioned heat exchanger 1 remains important. Such a heat exchanger 1 can also be used to heat a cryogenic fluid contained in a storage. The heat exchanger 1 is for example located outside the storage and provides heat exchange between the cryogenic fluid taken from the storage and a hotter fluid (air, water or other heat transfer fluid) to vaporize it.

By way of example, such a heat exchanger 1 can be used to cool and / or heat nitrogen, helium, hydrogen, argon or a mixture of all or part of these components. in cryogenic form by heat exchange with a cryogenic fluid or not: nitrogen, helium, hydrogen, argon or a mixture of all or part of the latter and / or water.

Claims

1. Method for cryogenic cooling of a first fluid

(2) by heat exchange with at least a second fluid (3) in a heat exchanger (1), the first fluid (2) and / or the second fluid (3) being at a temperature between -100 ° C and -273 ° C, characterized in that the heat exchanger (1) is of the polymer microtube type, that is to say comprising a plurality of polymer microtubes (4) and having a diameter between and 0.1mm and 1mm, one of the first (2) and second

(3) fluids being circulated inside said micro tubes (4) while the other fluid is circulated around said micro tubes (4) and that the heat exchanger (1) comprises a housing (5) in which the microtubes (4) are arranged, the housing (5) comprising a first inlet (6) communicating with a first end of the microtubes (4), the housing (5) comprising a first outlet (7) ) communicating with a second end of the micro-tubes (4), the housing (5) also comprising a second inlet (8) and a second outlet (9) communicating with the volume located around the micro-tubes

(4).

2. Method according to claim 1, characterized in that the micro-tubes (4) consist of at least one of the following materials: polyetheretherketone (PEEK), Polytetrafluoroethylene (PTFE), Polyetherimide, polyimides, polyamides, polycarbonates or all other plastic material compatible with use at said low temperatures.

3. Method according to claim 1 or 2, characterized in that the microtubes (4) consist of a material comprising a mixture of polyetherimide (“Ultem”) and Peek.

4. Method according to any one of claims 1 to 3, characterized in that the micro-tubes (4) consist of a material having a density of between 2700kg / m ³ and 900kg / m ³ and in particular less than 1500kg / m ³ .

5. Method according to any one of claims 1 to 4, characterized in that the micro-tubes (4) have a diameter between 0.1mm and 5mm.

6. Method according to any one of claims 1 to 5, characterized in that the pressure differential between the pressure of the fluid (2) circulated in the micro-tubes (4) and the pressure of the fluid (3) circulated around the micro-tubes (4) is between 1 bar and 100 bar and in particular between 10 and 50 bar.

7. Method according to any one of claims 1 to 6, characterized in that the microtubes (4) are arranged in a bundle in a longitudinal direction in the housing (5).

8. Method according to any one of claims 1 to 6, characterized in that the micro-tubes (4) are wound helically, preferably distributed around a mandrel (20) central support.

9. The method of claim 7 or 8, characterized in that at least one of the two longitudinal ends of the bundle of microtubes (4) comprises a layer (13) of rigid material such as a thermosetting material ensuring the cohesion of the bundle of microtubes, the housing (5) housing at least one elastic member (11, 12) constrained in the longitudinal direction between a stop formed in the housing (5) and a longitudinal end of the bundle of microtubes, to ensure the longitudinal maintenance of the bundle of microtubes while allowing expansion or contraction relative to the housing (5) in the longitudinal direction.

10. The method of claim 9, characterized in that the elastic member comprises at least one of: a spring (11), a helical spring, one or more of elastic washers (12) in particular of the Belleville type.

11. The method of claim 9 or 10, characterized in that the housing (5) comprises an elastic zone (14) in the longitudinal direction such as a bellows.

12. Method according to any one of claims 1 to 11, characterized in that it ensures a heat exchange between more than two fluids, that is to say that distinct portions of the microtubes (4) and / or the volume around the micro-tubes (4) accommodate separate flows of fluid (s) for heat exchange in the heat exchanger (1).

13. Method according to any one of claims 1 to 12, characterized in that the cooling is carried out in a process of refrigeration and / or cryogenic liquefaction of a fluid, the heat exchanger (1) being located in a cryogenic refrigeration and / or liquefaction device.

14. Device for cryogenic cooling of at least one first fluid by heat exchange with at least one second fluid comprising a heat exchanger (1) providing heat exchange between the first fluid and the second fluid, the first and / or the second fluid. second fluid being at a temperature between -100 ° C and -273 ° C, the heat exchanger (1) being of the polymer microtube type, that is to say comprising a plurality of microtubes (4 ) made of polymer and having a diameter between and 0.1mm and 1mm, and that the heat exchanger (1) comprises a housing (5) in which are arranged the micro-tubes (4), the housing (5) comprising a first inlet (6) communicating with a first end of the micro-tubes (4), the housing (5) comprising a first outlet (7) communicating with a second end of the microtubes (4), the housing (5) also comprising a second inlet (8) and a second outlet (9) communicating with the volume located around the microtubes (4), a circulation of at least at least one fluid inside said microtubes (4) and a circulation of the other fluid around said microtubes.

15. Cooling device according to claim 14, characterized in that it comprises a working circuit (15) containing a working fluid, the working circuit (15) comprising at least one compressor (16) of the working gas, at least one heat exchanger (1) for cooling the compressed fluid, at least one member (17) for expanding the working fluid, at least one heat exchanger (1) for reheating the expanded working fluid, characterized in that the at least one cooling heat exchanger (1) and / or the at least one reheating heat exchanger (1) is of the type with polymer micro tubes, that is to say comprising a plurality of micro tubes (4) made of polymer and having a diameter between and 0.1mm and 10mm, and comprising inlets (6, 8) and outlets (7, 9) for a first flow of working fluid and another fluid having a temperature distinct from the temperature of the first flow of working fluid, to ensure heat exchange between the pr first flow of working fluid and the other fluid.