DEVICE FOR HEATING TWO FLUID FLOWS

Abstract

The invention relates in particular to a device for heating two different fluid flows (F1, F2), which comprises: - a closed enclosure (1), delimited by an enclosure wall (11), in which a first fluid flow (F1) among said two fluid flows (F1, F2) can circulate between an enclosure inlet (12) and an enclosure outlet (14), said enclosure (1) extending along an axial direction (X), - a heat production element (4), capable of increasing the temperature of said first fluid flow (F1) circulating in said enclosure (1). The enclosure (1) is surrounded by a casing (3), defining an external chamber (30) to said enclosure (1) which extends between said casing (3) and said enclosure wall (11), in which a second fluid flow (F2) of the two fluid flows (F1, F2) can circulate around the enclosure (1) between a chamber inlet (32) and a chamber outlet (33). Figure for the abbreviation: [Fig. 1]

Description

Title of the invention: DEVICE FOR HEATING TWO FLUID FLOWS technical field

[0001] The present invention relates to a device for heating two fluid streams.

[0002] The invention finds particular application in SOEC or SOEL type systems comprising electrolyzers supplied with fluids whose temperature, at the inlet of the electrolyzer, must be raised to more than 500 °C, or even between substantially 700 and 800 °C.

[0003] The invention relates to an installation comprising at least one such device and enabling either the production of hydrogen by electrolysis of water vapor or the production of electricity. State of the art

[0004] In the field of dihydrogen production, it is known to carry out high-temperature electrolysis using an electrochemical device forming a reaction zone designed to convert water vapor into dihydrogen. In other words, the electrochemical device performs vapor-phase electrolysis with water vapor at a temperature that can range from 100°C to 850°C.

[0005] The reaction zone of a conventional electrolyzer is formed by stacks of cells, each having an anode, a cathode, and an electrolyte. High-temperature electrolysis decomposes water vapor to form, at the cell cathode, a flow of fluid comprising dihydrogen and unreacted water.

[0006] To enable this reaction, water vapor is introduced into an electrolyzer maintained at a temperature between approximately 700°C and 850°C.

[0007] This solution requires an external energy input, in particular to obtain water vapor at the desired temperature at the inlet of the electrolyzer.

[0008] Various systems are known that include heat exchangers and electric gas heaters installed on the steam (more commonly called fuel) inlet line and on the air inlet line. The gas heaters and exchangers allow, in particular, for increasing the temperature of the fuel (or the air in the air line) in order to reach the desired temperature at the inlet of the electrolyzer. These systems are also called "Hot Balance of Plant" or "Hot BoP" in English.

[0009] The invention aims, in particular, to provide a different electric gas heater with the objective of being less energy-intensive (for its implementation).

[0010] Another object of the invention is to provide a more compact electric gas heater. Description of the invention

[0011] To this end, the invention relates to a device for heating two different fluid streams, said device comprising: - a closed enclosure, delimited by an enclosure wall, in which a first fluid flow among said two different fluid flows can circulate between an enclosure inlet and an enclosure outlet, said enclosure extending along an axial direction, - a heat production element, capable of increasing the temperature of said first flow of fluid circulating in said enclosure.

[0012] According to the invention, the device is remarkable in that said enclosure is surrounded by an envelope, defining a chamber external to said enclosure which extends between said envelope and said enclosure wall, in which a second fluid flow, one of the two different fluid flows, can circulate around the enclosure between a chamber inlet and a chamber outlet.

[0013] Thus implemented, the device makes it possible to heat two different fluid flows by using the heat from one to heat the other. Indeed, the heat-producing element heats the first fluid flow in the enclosure, and the heat released by the enclosure (in which the first heated fluid flow circulates) heats the second fluid flow in the surrounding chamber by radiation.

[0014] This device according to the invention is, moreover, less bulky in an installation since it replaces two conventional heating devices.

[0015] According to the invention, the device may also include the following features, taken separately or in combination:

[0016] - said enclosure and said chamber are cylindrical and of concentric cross-section,

[0017] - the heat-producing element is positioned in said enclosure, preferably axially,

[0018] - the heat-producing element is contained within a sealed protective capsule containing an inert gas,

[0019] - according to this embodiment, said watertight protective capsule comprises a sealed tube which includes a section of tube, extending from said resistance, without a heating element: this allows heat exchange between the first and second fluid flows without the input of heat other than that of the flows of fluids, which allows for a thermal equilibrium leading to fluid flows at approximately the same temperature at the device outlet,

[0020] - more advantageously, according to an alternative embodiment, said airtight tube includes a second tube section, extending from said resistor, which comprises an insulating material: this allows for electrical connections to be made in this part of the device.

[0021] - said watertight protective capsule may include a capsule wall which is equipped with protruding radial studs, ensuring the centering of said capsule within said enclosure, said studs having a stud height substantially equal to the distance between the wall of the enclosure and the wall of the capsule: this guarantees that the capsule is well centered within the enclosure, for homogeneous heating of the first fluid flow within the enclosure,

[0022] - preferably, said sealed capsule is mounted mobilely when moving within said enclosure and advantageously, the device includes a differential expansion compensation system: this makes it possible to compensate for the differential expansions between the enclosure and the chamber, these differences in expansion being due to the temperature increase of the flow caused by the heat-producing element,

[0023] - said heat-producing element may include at least one resistor electric,

[0024] - according to a first embodiment, the electrical resistance is formed by at at least two rods extending in a direction parallel to said axial direction, said at least two rods being held in position relative to each other by means of at least two discs, preferably ceramic, said at least two rods passing through said at least two discs and said at least two discs being axially threaded onto a central positioning rod extending in a direction parallel to said at least two rods forming electrical resistance,

[0025] - according to an alternative embodiment, the electrical resistance is formed by a bar central extending axially within said enclosure, said resistance bar being held in the axis of said enclosure by at least two transverse disks, said bar passing through said at least two disks at their center,

[0026] - in addition, the device includes a removable closure flange at one end of device, allowing access to said heat-producing element,

[0027] - preferably, said enclosure inlet comprises an inlet conduit which passes through axially, said chamber at a first end of said enclosure, and said enclosure outlet includes an outlet duct which is provided radially through said chamber, at a second end of the enclosure.

[0028] - preferably, the chamber entrance is arranged radially to a first end of envelope and in that said chamber outlet is provided radially at a second end of envelope.

[0029] The invention finally relates to an installation comprising at least one electrochemical device and two supply lines in which two different fluid flows circulate, said installation being remarkable in that it comprises at least one device as defined above, connected to the two lines and positioned upstream of said electrochemical device.

[0030] Advantageously, it may be provided that said at least one device is thermally insulated in a casing. Brief description of the figures

[0031] The invention will be better understood upon reading the following description, given solely by way of non-limiting example and made with reference to the accompanying drawings in which:

[0032] [Fig-1]: [Fig.1] is a longitudinal cross-sectional view of a device conforming to a first embodiment of the invention,

[0033] [Fig.2]: [Fig.1] is a cross-sectional view of the device shown in [Fig.1]. following plan ILII,

[0034] [Fig.3]: [Fig.3] is a cross-sectional and perspective view of the device shown in [Fig. 1], following plan IV-IV, and

[0035] [Fig.4]: [Fig.4] is a longitudinal cross-sectional view of a device conforming to a second embodiment of the invention.

[0036] It is understood that the embodiments described below are in no way limiting. In particular, variants of the invention may be conceived comprising only a selection of the features described below, isolated from the other features described, if this selection of features is sufficient to confer a technical advantage or to differentiate the invention from the prior art. This selection includes at least one preferably functional feature without structural details, or with only a portion of the structural details if this portion alone is sufficient to confer a technical advantage or to differentiate the invention from the prior art.

[0037] In particular, all the variants and embodiments described are combinable with each other if there is no technical obstacle to this combination.

[0038] In the figures and in the rest of the description, elements common to several figures retain the same reference. Detailed description

[0039] Fig. 1 illustrates a first embodiment of a device according to the invention.

[0040] It comprises a tubular enclosure 1 (cylindrical in this embodiment) delimited by an enclosure wall 11 of circular and hollow section, having an enclosure axis X.

[0041] The tubular and hollow enclosure 1 includes, at a first closed end 10, an axial opening which constitutes an enclosure inlet 12, the axial opening passing through the closed end to communicate the interior of the enclosure with a conduit 16 opening outside the device.

[0042] The end opposite the closed end 10 of the enclosure 1 is open and traversed by a capsule 2, which will be presented subsequently. A seal ensures a tight seal between the outer wall of the capsule 2 and the inner wall of the enclosure at the end 13, so that the end 13 of the enclosure does not allow any fluid to pass from the inside of the enclosure 1 and the capsule 2 to the outside of the device.

[0043] An enclosure outlet 14 is provided radially in the vicinity of the end 13 of the enclosure by a radial through opening which communicates the inside of the enclosure and the outside of the device through a conduit 18.

[0044] Thus, a first fluid flow Fl can cross the enclosure 1 by entering through the enclosure inlet 12 and exiting the enclosure through the enclosure outlet 14.

[0045] As provided by the invention, the enclosure 1 is surrounded by an envelope 3, which defines a chamber 30 around the enclosure 1.

[0046] The chamber 30 extends between the enclosure wall 11 and the envelope.

[0047] The envelope 3 is tubular, cylindrical (in this embodiment) and coaxial with the envelope: the envelope 3 and the enclosure thus have the same X axis.

[0048] The chamber 30 is thus at least partially annular around the enclosure 1.

[0049] The envelope 3 includes a chamber entrance 32 which is provided at one end 31 of the envelope (the end 31 of the envelope surrounds the end 10 of the enclosure 1): the chamber entrance 32 is made by a radial through opening.

[0050] An outlet 33 of chamber 30 is provided at another end 34 of the envelope which is opposite the end 31 of the envelope.

[0051] Thus constructed, the annular chamber allows the introduction of a second fluid flow F2 through its inlet 32 ​​through the end 31 of the envelope 3, the circulation of the fluid around the enclosure 1 and its outlet 33 through the end 34 of the envelope 3.

[0052] In the context of a particular application mode of this device, which is not limiting, it is provided that the fluid flow Fl to be heated is air and that the fluid flow F2 is a fuel, such as water vapor enriched in dihydrogen, for example.

[0053] To enable the heating of the first and second fluid flows Fl and F2, the device according to the invention includes a heat production element 4 which is capable of increasing the temperature of the fluid flow Fl circulating in the enclosure 1.

[0054] In this first embodiment, the heat production element 4 is isolated from the fluid flow Fl by being integrated into the capsule 2 which will now be described.

[0055] The capsule 2 is in the form of a tube positioned in the enclosure 1: to ensure its centering, projecting radial pads 20 are provided at specific points around the tube and come into contact with the inner wall of the enclosure: [Fig. 2] illustrates these pads on a cross-sectional view of the device shown in [Fig. 1]. The pads 20 are all identical and have a pad height approximately equal to the distance between the wall of the enclosure and the wall of the capsule.

[0056] It is also observed, on [Fig.2], that the envelope 3 is kept centered around the wall 11 of the enclosure 1 also thanks to the presence of radial studs 15 protruding from the wall 11 and bearing against the inner face of the wall of the envelope 3.

[0057] The pads 20 are three in number and are uniformly distributed around the capsule 2, and the pads 15 are also three in number and uniformly distributed around the wall 11 of the enclosure 1.

[0058] Capsule 2 comprises an inert gas.

[0059] The heat-producing element 4, which is located in the inert gas within the capsule 2, is preferably made up of one or more elements forming electrical resistances. In this embodiment, the heat-producing element 4 comprises a set of resistances formed by rods 40 that extend axially within the capsule tube and are distributed uniformly around the axis of the tube forming the capsule.

[0060] The rods 40 of the heat-producing element 4 are held in position by being threaded into holes provided in ceramic discs 41, positioned transversely in the tube.

[0061] It should be understood that the discs could be replaced by any other medium, without departing from the scope of the invention, the media being able to be made in another form and in another material according to the requirements.

[0062] All the ceramic discs 41 are threaded onto a central retaining rod 42, the central rod 42 being fixed in the axis of the capsule tube 2 which is coincident with the X axis of the enclosure (and device in general).

[0063] As shown in [Fig.1], the tube comprises nine ceramic discs 41, with the same distance separating two contiguous discs 41, and distributed over the entire length of the rods 40 of the heat-producing element 4 (or substantially the entire length).

[0064] Fig. 3 shows another cross-sectional and perspective view of the device: the free end of the rods 40 and the concentric walls of the capsule tube 2, the enclosure wall and the envelope 3 are shown.

[0065] It is noted that the fluid flow Fl circulating in the enclosure 1 is in contact with the wall of the capsule tube, the heat of which is increased by the heat-producing element 4 (the rods 40), and that the fluid flow F2 circulating in the annular chamber 30 is in contact with the wall of the enclosure, which transfers to it the heat it receives.

[0066] Thus, the heat from the electrical resistance rods 40 heats the capsule, which transfers heat to the fluid flow Fl circulating in the enclosure 1, which also transfers heat to the fluid flow F2 circulating in the annular chamber 30.

[0067] In parallel, the capsule (11) also transmits heat by radiation to the wall 3. This wall then transmits some of the heat by convection to the fluid F2. The distribution between these different modes of heat exchange depends on the gas flow rates, the operating temperatures, and the dimensions of the annular spaces.

[0068] Thus, a single heat-producing element 4 makes it possible to heat two separate fluid flows without additional electrical energy input and over the same length of device: the device according to the invention is therefore more compact and more economical than the implementation of two heating devices of the Prior Art which are implemented, each on a fluid flow conduit.

[0069] It should also be noted that the petal-like shape of the periphery of the ceramic discs 41 is a particular shape which allows air to circulate between the wall of the capsule tube and the peripheral edge of the disc 41, which has the function of allowing heat exchange by radiation between the different cutouts (between the petal shapes) formed by the discs.

[0070] In [Fig. 1], it can be seen that the heat-producing element 4 does not extend over the entire length of the capsule tube: indeed, a part 43 of the tube contiguous to that containing the heat-producing element 4 (on the left in [Fig. 1]) does not include a heat-producing element 4: this allows for heat exchange between the enclosure 1 and the annular chamber 30 without the effect of the heat-producing element 4, making it possible to reach a thermal equilibrium so that the fluid flows Fl and F2 reach substantially the same temperature at the outlets of the device (i.e. at the outlet 14 of the first fluid flow Fl and at the outlet 33 of the second fluid flow F2).

[0071] A second tube section 44, adjacent to the first tube section 43 (which does not include a heat-producing element 4), comprises an insulating material. This section of the capsule allows for electrical connections to be made for the heat-producing element.

[0072] When the first fluid flow Fl is heated, the pressure in the enclosure can vary. Therefore, the sealed capsule 2 is designed to be mounted to move freely within the enclosure 1: the arrows "d" in [Fig. 1] indicate the movement of the capsule within the enclosure, similar to the movement of a piston.

[0073] A system 5 for compensating differences in expansion between the enclosure and the chamber is also provided. The system 5 is provided in said enclosure or in a fluid flow inlet 16 communicating with the enclosure inlet 12, as shown in [Fig. 1].

[0074] It will be noted that the fluid flow inlet 16 Fl passes through the end of the chamber 30 to connect the inside of the enclosure and the outside of the device, in the X axis of the device.

[0075] Figure 4 illustrates a non-limiting variant embodiment of a device according to the invention.

[0076] References designating elements having the same function have been retained between [Fig.1] and [Fig.4].

[0077] According to this embodiment, the device comprises an enclosure 1, and an envelope 3 surrounding the enclosure 1.

[0078] An enclosure inlet 12 is provided at one end of the enclosure 10: the enclosure inlet 12 is provided at the outlet of a conduit 16, which passes axially through the enclosure 3 at its end 31.

[0079] An enclosure outlet 14 is provided radially at the enclosure end 13, opposite the end 10. The enclosure outlet 14 communicates with a radial outlet conduit 18 which passes through the enclosure 3 at its end 34, opposite the enclosure end 31.

[0080] The inlet and outlet conduits are designed to connect to supply or discharge conduits for fluid flow.

[0081] As in the first example, the envelope 3 forms an annular chamber 30 around the enclosure 1. The chamber inlet is provided radially at the end 31 of the envelope and the chamber outlet is also provided radially at the end 34 of the envelope.

[0082] A compensation system 5 may be provided in the conduit 16.

[0083] The enclosure includes the heat-producing element 4, which is made by a central bar 17 extending axially in the enclosure 1. The central bar 17 is a resistor.

[0084] The central bar 17 is held in the enclosure by at least two transverse discs: one of the discs is a ceramic disc 41 which is inserted into the enclosure and positioned near its end 10. The other disc is made by a removable flange 35, comprising a central opening to accommodate one end of the bar 17.

[0085] In this embodiment, the first fluid flow Fl circulating in the enclosure is in direct contact with the heat-producing element. Preferably, the first fluid flow is an air flow.

[0086] As for the second fluid flow F2, which circulates in the annular chamber around the enclosure, it is a fuel flow, for example a water vapor flow possibly enriched in dihydrogen.

[0087] The removable flange 35 allows access to said crossbar, for example, to change it in case of maintenance of the device.

[0088] As in the first example, it is intended that the bar 17 does not heat up over the entire length of the enclosure: The bar 17 does not produce heat in a first part of the enclosure 43 to allow the first fluid flow Fl and the second fluid flow F2 to equalize their temperature through the enclosure wall.

[0089] The embodiment shown in [Fig. 4] is less expensive and simpler to implement than the embodiment shown in [Fig. 1], because the heat-producing element is not isolated from the fluid flow Fl through the enclosure. However, this embodiment is intended for heating a first fluid flow Fl that is only slightly corrosive to the bar 17 of the heat-producing element.

[0090] It is understood from the preceding description how the invention makes it possible to heat two fluid flows at the same time, with the same device, in particular by using the heat emitted by a first fluid flow to heat a second fluid flow.

[0091] It is also understood how the device saves space in an installation, since only one device is needed instead of two.

[0092] The invention also offers cost savings because it eliminates the need for certain equipment and upstream logistics: It is estimated that the total CAPEX savings are around 50% between a device (heater) according to the invention and the use of two separate conventional devices (heaters). Furthermore, these advantages are combined with an efficiency gain of around 10 to 15% compared to the use of two conventional heating devices.

[0093] Of course the invention is not limited to the examples just described and extends to the implementation of any equivalent means.

Claims

Demands

1. A device for heating two different fluid streams (F1, F2), said device comprising: - a closed enclosure (1), delimited by an enclosure wall (11), in which a first fluid stream (F1) of said two different fluid streams (F1, F2) can flow between an enclosure inlet (12) and an enclosure outlet (14), said enclosure (1) extending along an axial direction (X), - a heat-generating element (4) capable of increasing the temperature of said first fluid stream (F1) flowing in said enclosure (1), said device being characterized in that said enclosure (1) is surrounded by an envelope (3), defining an external chamber (30) to said enclosure (1) which extends between said envelope (3) and said enclosure wall (11), in which a second fluid stream (F2) of said two different fluid streams (F1, F2) can flow around the enclosure (1) between an inlet of room (32) and a room exit (33).

2. Device according to claim 1, characterized in that said enclosure (1) and said chamber (3) are cylindrical and of concentric sections.

3. Device according to claim 1 or 2, characterized in that the heat-producing element (4) is positioned, preferably axially, in said enclosure (1).

4. Device according to claim 3, characterized in that the heat-producing element (4) is contained in a sealed protective capsule (2) comprising an inert gas.

5. Device according to claim 4, characterized in that said sealed protective capsule (2) comprises a sealed tube which includes a tube portion (43), in the extension of a resistance, without a heating element.

6. Device according to claim 5, characterized in that said sealed tube comprises a second tube part (44), in the extension of said resistance, which comprises an insulating material.

7. Device according to any one of claims 4 to 6, characterized in that said watertight protective capsule (2) comprises a capsule wall which is equipped with radial studs protruding (20), ensuring the centering of said capsule (2) in said enclosure (1), said studs (20) having a stud height substantially equal to the distance between the enclosure wall (11) and the capsule wall (2).

8. Device according to any one of claims 4 to 7, characterized in that said sealed capsule (2) is mounted movable in movement in said enclosure (1).

9. Device according to any one of the preceding claims, characterized in that it comprises a system (5) for compensating for differential expansion of said enclosure and said chamber.

10. Device according to any one of the preceding claims, characterized in that said heat-producing element (4) comprises at least one electrical resistance.

11. Device according to claim 10, characterized in that the electrical resistance is formed by at least two rods (40) extending in a direction parallel to said axial direction (X), said at least two rods (40) being held in position relative to each other by means of at least two discs (41), preferably ceramic, said at least two rods (40) passing through said at least two discs (41) and said at least two discs (41) being axially threaded onto a central positioning rod (42) which extends in a direction parallel to said at least two rods (40) forming electrical resistance.

12. Device according to claim 10, characterized in that the electrical resistance is formed by a central bar (17) extending axially in said enclosure (1), said central bar (17) forming resistance and being held in the axis (X) of said enclosure (1) by at least two transverse discs, said bar passing through said at least two discs at their center.

13. Device according to any one of the preceding claims, characterized in that it comprises a removable flange (35) for closing one end of the device, allowing access to said heat-producing element.

14. A device according to any one of the preceding claims, characterized in that said enclosure inlet (12) comprises an inlet conduit (16) which axially passes through said chamber (30) at a first end (31) of said enclosure (3) and in that said enclosure outlet (14) comprises an outlet conduit (18) which is provided radially through said chamber (30), at a second end of envelope (34).

15. Device according to any one of the preceding claims, characterized in that said chamber inlet (32) is formed radially at a first end (31) of envelope (3) and in that said chamber outlet (33) is formed radially at a second end (34) of envelope (3).

16. Installation comprising at least one electrochemical device and two supply lines through which two different fluid flows circulate, said installation being characterized in that it comprises at least one device according to any one of the preceding claims connected to the two lines and positioned upstream of said electrochemical device.

17. Installation according to claim 16, characterized in that said at least one device is thermally insulated in a housing.

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