Device and method for heating a fluid stream

Abstract

The invention relates to a device for heating a cryogenic fluid stream comprising a set of heat exchanger(s) (2, 3) defining, arranged in series, two heat exchange portions, each comprising at least one first passage (12, 13) for the cryogenic fluid stream to be heated and at least one second passage (22, 23) for a heating heat transfer fluid, the passages being configured to exchange heat, the device (1) comprising a first set of pipes (120, 121, 122) having a set of valve(s) (123, 124) and configured to guide cryogenic fluid in the first passages (12, 13), a second set of pipes (32) configured to guide heat transfer fluid in the second passages (22, 23), wherein the first set of pipes (120, 121, 122) and the set of valve(s) (123,124) corresponding are configured to allow reversing the order of passage of the cryogenic fluid flow in the two series heat exchange portions. Abbreviated figure: Fig. 1,

Description

Title of the invention: Device and method for heating a fluid flow

[0001] The invention relates to a device and a method for heating a flow of fluid, in particular cryogenic fluid.

[0002] The invention relates more particularly to a device for heating a flow of cryogenic fluid, for example for the vaporization of liquid hydrogen, comprising a set of heat exchanger(s) defining, arranged in series, two heat exchange portions each comprising at least a first passage for the flow of cryogenic fluid to be heated and at least a second passage for a heating heat transfer fluid, the first and second passages being configured to exchange heat, the device comprising a first set of pipes comprising a set of valve(s) and configured to guide cryogenic fluid in the first passages, a second set of pipes configured to guide heat transfer fluid in the second passages.

[0003] For reasons of increasing energy density, hydrogen is often stored in liquid form while its final use is most often close to room temperature, for example in a fuel cell.

[0004] It is then essential to provide a heating system between the liquid sampling point and its final use. This heating can be done, for example, with atmospheric exchangers, but these installations require a lot of volume and access to the ambient air, which is not always possible. In addition, the freezing of these exchangers (frost) limits continuous use and is difficult to assess in the design (sizing).

[0005] Other systems use a heating heat transfer fluid, but the latter is always subject to the risk of solidification because, except for helium, all fluids solidify at the boiling temperatures of hydrogen. In this case, two main operating strategies exist: in a first strategy this freezing is provided for in the dimensioning of the heat exchanger. The passage sections on the heat transfer fluid side are provided to be large enough to ensure flow under all conditions. In a second strategy, a dimensioning is carried out in which the heat exchange coefficient on the heat transfer fluid side is much higher than the heat exchange coefficients on the side of the hydrogen to be cooled.In addition, the thickness separating the two fluids makes it possible to homogenize the temperatures so that the wall temperature on the heat transfer fluid side is always above the solidification temperature of the latter.

[0006] These two strategies have the disadvantage of requiring a large volume and especially a large mass for the exchanger. This can be a major problem in certain applications. In addition, this large mass does not allow the hydrogen temperature to be regulated quickly as in other types of exchangers, because the thermal inertia of the exchanger itself is a significant obstacle. These systems also often have a relatively reduced operating range in terms of flow and pressure.

[0007] There is also the possibility of heating the hydrogen at least in part using heat produced by electrical resistance, but this is an economically and ecologically advisable solution.

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

[0009] 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 first set of pipes and the set of corresponding valve(s) are configured to allow the order of passage of the cryogenic fluid flow to be reversed in the two heat exchange portions in series.

[0010] Furthermore, embodiments of the invention may include one or more of the following features: - the first set of pipes and the set of valve(s) are configured to allow the order of passage of the cryogenic fluid flow in the two heat exchange portions in series to be reversed by reversing the direction of passage of the cryogenic fluid in the first passages without reversing the direction of circulation of the heating heat transfer fluid in the second passages, - the cryogenic fluid flow and the heat transfer fluid are co-current or counter-current in one or less of the heat exchange portions, - the set of valve(s) of the first set of pipes comprises a set of pilot-controlled valves configured to reverse the order of passage of the cryogenic fluid flow in the two heat exchange portions in series in response to a control signal, for example in response to a physical quantity value relating to the cryogenic fluid flow or to the heat transfer fluid in the device, - the device comprises an electronic data storage and processing unit comprising a microprocessor and configured to control all or part of the set of controlled valves, - the device comprises at least one sensor for measuring a physical quantity value relating to the flow of cryogenic fluid and / or to the heating heat transfer fluid, for example a temperature, a flow rate, a state, - the electronic data storage and processing unit is configured control all or part of the set of controlled valves according to the value measured by the at least one measuring sensor in relation to a reference value, - the two heat exchange portions arranged in series belong to a single exchanger or to two separate heat exchangers, for example identical heat exchangers, - the heat exchanger or at least one of the heat exchangers is of the plate type or of the tube(s) type, for example with the second passage arranged around the first passage, - the device comprises a heat exchanger or an additional heat exchange portion arranged in series downstream of the two heat exchange portions and ensuring a heat exchange between the cryogenic fluid which has passed through the two heat exchange portions and a heat transfer fluid.

[0011] The invention also relates to a method for heating a flow of cryogenic fluid, for example liquid hydrogen, using a heating device conforming to any one of the characteristics above or below, in which, during a first step, a flow of cryogenic fluid to be heated is circulated in the first passages of the two heat exchange portions in series in a first order and a first direction of circulation and, simultaneously, a heating heat transfer fluid is circulated in the second passages, the method comprising a step of reversing a flow of cryogenic fluid to be heated in the first passages of the two heat exchange portions in series, that is to say in a second order and second direction of circulation opposite respectively to the first order and first direction of circulation.

[0012] According to other possible particularities: - during the first stage, the flows of cryogenic fluid to be heated and of heating heat transfer fluid circulate in the same direction, i.e. co-currently in the first of the two heat exchange portions in series, - , during the first stage, the flows of cryogenic fluid to be heated and of heating heat transfer fluid circulate in opposite directions, i.e. counter-current in the second of the two heat exchange portions in series, - the device is configured so that, at the outlet of the first of the two heat exchange portions in series, i.e. between the two heat exchange portions, the temperature of the cryogenic fluid is kept higher than the solidification temperature of the heat transfer fluid, - the inversion step is triggered in response to the detection of at least one parameter representing the appearance or risk of appearance of solidification of the heat transfer fluid in a heat exchange portion, - the at least one representative parameter of appearance comprises at least one of: a variation in flow rate of the heat transfer fluid, a variation in temperature of the cryogenic fluid and / or the heat transfer fluid, a temperature level of the cryogenic fluid and / or the heat transfer fluid, a variation in the pressure drop within the device.

[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.

[0014] Other features and advantages will appear on reading the description below, given with reference to the figures in which: Brief description of the figures

[0015] The invention will be better understood on reading the following description given solely by way of example and with reference to the appended drawings in which:

[0016] [Fig. 1] is a schematic and partial view illustrating an example of structure and operation of a heating device according to a first exemplary embodiment of the invention,

[0017] [Fig.2] is a schematic and partial view illustrating an example of structure and operation of a heating device according to a second exemplary embodiment of the invention. Detailed description

[0018] In all the figures, the same references refer to the same elements.

[0019] 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. Single features of different embodiments may also be combined and / or interchanged to provide other embodiments.

[0020] The device 1 for heating a flow of cryogenic fluid illustrated in [Fig.l] can be used, for example, for vaporizing or heating liquid hydrogen. The device 1 can also be used for a non-cryogenic fluid (for example which is liquid at a temperature above 150°C or above -100°C).

[0021] More generally, this device 1 can be used for heating fluid (hydrogen for example) by heat exchange with a heat transfer fluid whose solidification temperature is higher than the inlet temperature of the fluid to be heated.

[0022] This device 1 comprises a set of heat exchanger(s) 2, 3 (two heat exchangers arranged in series in this example) defining two heat exchange portions in series on the path of a flow of fluid, for example cryogenic, to be heated. Each heat exchange portion comprises at least a first passage 12, 13 for the flow of cryogenic fluid to be heated and a second passage 22, 23 for a heating heat transfer fluid, the first and second passages being in heat exchange.

[0023] The device 1 comprises a first set of pipes 120, 121, 122 comprising a set of valves 123, 124 and configured to guide cryogenic fluid into the first passages 12, 13. The first set of pipes brings the fluid to the inlet of the first passage(s) of a first heat exchange portion and then recovers the fluid that has circulated therein at at least one outlet of the first heat exchange portion and guides the flow to the inlet of the first passage(s) of the second heat exchange portion. The circuit recovers the fluid that has circulated in the second heat exchange portion at at least one outlet. This heated cryogenic fluid can then be directed to a downstream application.

[0024] The device 1 also comprises a second set of pipes 32 configured to guide heat transfer fluid into the second passages 22, 23 of the two heat exchange portions. In the example illustrated, an independent heat transfer fluid circuit is provided for each heat exchange portion.

[0025] According to an advantageous feature, the first set of pipes 120, 121, 122 and the corresponding set of valve(s) 123, 124 are configured to allow the order of passage of the cryogenic fluid flow in the two heat exchange portions in series to be reversed. That is to say that the fluid distribution system allows the order of passage of the fluid to be heated in these two heat exchange portions to be reversed.

[0026] As illustrated in [Fig.l], in a first non-limiting configuration (before inversion), the flow of cryogenic fluid and the heat transfer fluid are preferably oriented co-currently (same direction) in the first heat exchange portion and counter-currently (opposite directions) in the second heat exchange portion. In this example, each heat exchange portion is crossed by the heat transfer fluid in the same direction. That is to say that, in this example, the two heat transfer fluid flows arrive from the same side (for example longitudinal) and leave from another same side (for example longitudinal).

[0027] For example, the first set of pipes 120, 121, 122 and the set of valve(s) 123, 124 make it possible to reverse the order of passage of the cryogenic fluid flow in the two heat exchange portions in series by reversing the direction of passage of cryogenic fluid in the first passages 12, 13 without reversing the direction of circulation of the heating heat transfer fluid in the second passages. For this purpose, the ends of the first passages 12 of the two heat exchange portions located on the same side can be connected in parallel to an inlet of cryogenic fluid to be heated, for example via parallel pipes and a set of valves 123.

[0028] These same ends of the first passages 12 of the two heat exchange portions which do not open between the two heat exchange portions can be connected in parallel to an outlet for heated cryogenic fluid, for example via parallel pipes and a set of valves 124. In the example illustrated, four two-way valves 123, 124 are used, but it is possible to provide another number of valves, for example by using three-way valves.

[0029] Compared to the first flow configuration symbolized in [Fig.l] with arrows (open valves in white and closed valves in black), the inversion of the path of the flow of cryogenic fluid to be heated can be obtained by reversing the openings / closings of the valves (reversed path in dotted lines).

[0030] The set of valves 123, 124 of the first set of pipes 120, 121, 122 comprises for example a set of controlled valves configured to reverse the order of passage of the flow of cryogenic fluid in the two heat exchange portions in series in response to a control signal, for example in response to a physical quantity value relating to the flow of cryogenic or heat transfer fluid in the device.

[0031] The device 1 may comprise an electronic data storage and processing member 5 comprising a microprocessor and configured to control all or part of the set of controlled valves.

[0032] The device may comprise at least one sensor 4 for measuring a physical quantity value relating to the flow of cryogenic fluid and / or to the heating heat transfer fluid, for example a temperature, a flow rate, a state, to trigger (automatically) the inversion of the flow.

[0033] For example, the inversion can be triggered in response to the measurement 4 of a determined low threshold of temperature of the cryogenic fluid to be heated measured at the outlet of the first heat exchange portion.

[0034] Any other alternative or cumulative parameter may be considered to generate the inversion, for example a measured or calculated or estimated parameter representative of the occurrence or risk of occurrence of excessive solidification of the heat transfer fluid in a heat exchange portion. For example, at least one of the following parameters (measured or calculated) may trigger the inversion: a variation in the flow rate of the heat transfer fluid, a variation in the temperature of the cryogenic fluid and / or the heat transfer fluid, a temperature level of the cryogenic fluid and / or the fluid heat transfer fluid, a variation in the pressure loss within the device.

[0035] Thus, in the event of detection of the formation of too large a layer of solid (for example by unbalancing the flow rates of the heat transfer fluid or by a drop in temperature of the fluid to be cooled at the outlet of the exchanger used in co-current or by an increase in the pressure drop of the heat transfer fluid through the exchanger), the inversion is triggered. The partially heated fluid (temperature higher than the solidification temperature of the heat transfer fluid) is put into heat exchange with the solidified portion which will thus be heated and re-liquefied. This solid will therefore be liquefied quickly and the passage cleared again. This will make it possible, if necessary, to reverse the order of the exchangers again in the event of detection of the start of blockage in the other passage or portion.

[0036] This solution makes it possible to temporarily solidify the heat transfer fluid for a certain time, before liquefying this solid. The structure of the device does not require the entire system to be split to ensure this function.

[0037] In the illustrated example, the two heat exchange portions are formed in two separate (for example identical) heat exchangers. Of course, these two heat exchange portions could be formed within the same heat exchanger.

[0038] Furthermore, the illustrated example provides concentric tube exchangers (heat transfer fluid around the fluid to be heated), but other types of heat exchanger technologies (as well as their combinations) are possible: “tube-in-tube”, “multitube-in-tube”, “plate” type heat exchangers.

[0039] Preferably, the or at least one of the heat exchangers has, for each fluid, a single fluid distributor at the inlet and a single fluid collector at the outlet. For example, for the heat transfer fluid, the distributor (inlet) and the collector (outlet) may be common to both portions. Similarly, it is possible to provide a single shell for the heat transfer fluid for both portions and two or more tubes for the fluid to be heated.

[0040] The two heat exchange portions may be sized so that each does not provide all of the desired final heating of the cryogenic fluid. For example, each heat exchange portion is configured to provide heating of the cryogenic fluid to a temperature above the solidification temperature of the heat transfer fluid.

[0041] Thus, while the fluid to be heated enters co-currently into the first heat exchange portion, it heats up to above the solidification temperature of the heat transfer fluid. This partially heated fluid then passes into the second heat exchange portion from where it leaves at a temperature close to the tem- heat transfer fluid inlet temperature.

[0042] Also preferably, the heat exchange portions are sized so that the heat transfer coefficient on the heat transfer fluid side is much higher than the heat exchange coefficient on the side of the fluid to be cooled.

[0043] Preferably the device is thermally insulated, but preferably without a vacuum.

[0044] In the case of such an installation, the flow of heated fluid may be subjected to temperature variations, in particular following the passage of the heated fluid through parts of the pipework previously crossed by very cold fluid. To smooth or even overheat the fluid, an additional heat exchanger 3 or heat exchange portion may be provided in series downstream as illustrated in [Fig.2] (passages 13, 23, heat transfer fluid circuit 32 which may be a separate heat transfer fluid flow different from that used for the aforementioned portions). That is to say, a third exchanger (co-current or preferably counter-current) may be provided downstream to further heat the cryogenic fluid or to stabilize its temperature.

[0045] The invention allows heating to operate continuously even with variable operating conditions. The device is light and compact and can use a conventional heat transfer fluid.

Claims

Claims

1. Device for heating a flow of cryogenic fluid, for example for the vaporization of liquid hydrogen, comprising a set of heat exchanger(s) (2, 3) defining, arranged in series, two heat exchange portions each comprising at least a first passage (12, 13) for the flow of cryogenic fluid to be heated and at least a second passage (22, 23) for a heating heat transfer fluid, the first and second passages being configured to exchange heat, the device (1) comprising a first set of pipes (120, 121, 122) comprising a set of valve(s) (123, 124) and configured to guide cryogenic fluid in the first passages (12, 13), a second set of pipes (32) configured to guide heat transfer fluid in the second passages (22, 23), in which, the first set of pipes (120, 121, 122) and the valve assembly(s) (123,124) are configured to allow the order of passage of the cryogenic fluid flow in the two heat exchange portions in series to be reversed, characterized in that the first set of pipes (120, 121, 122) and the set of valve(s) (123, 124) are configured to allow the order of passage of the cryogenic fluid flow in the two heat exchange portions in series to be reversed further by reversing the direction of passage of the cryogenic fluid in the first passages (12, 13) without reversing the direction of circulation of the heating heat transfer fluid in the second passages (22, 23).,

2. Device according to claim 1, characterized in that the flow of cryogenic fluid and the heat transfer fluid are co-current or counter-current in one or less of the heat exchange portions.

3. Device according to any one of claims 1 to 2, characterized in that the set of valve(s) (123, 124) of the first set of pipes (120, 121, 122) comprises a set of piloted valves configured to reverse the order of passage of the cryogenic fluid flow in the two heat exchange portions in series in response to a control signal, for example in response to a physical quantity value relating to the cryogenic fluid flow or to the heat transfer fluid in the device.

4. Device according to claim 3, characterized in that it comprises an electronic data storage and processing member (5). comprising a microprocessor and configured to control all or part of the set of piloted valves.

5. Device according to any one of claims 1 to 4, characterized in that it comprises at least one sensor (4) for measuring a physical quantity value relating to the flow of cryogenic fluid and / or to the heating heat transfer fluid, for example a temperature, a flow rate, a state.

6. Device according to claims 4 and 5, characterized in that the electronic data storage and processing member (5) is configured to control all or part of the set of controlled valves as a function of the value measured by the at least one measurement sensor (4) relative to a reference value.

7. Device according to any one of claims 1 to 6, characterized in that the two heat exchange portions arranged in series belong to a single exchanger or to two separate heat exchangers, for example identical heat exchangers.

8. Device according to claim 7, characterized in that the heat exchanger or at least one of the heat exchangers is of the plate type or of the tube(s) type, for example with the second passage (22, 23) arranged around the first passage (12, 13).

9. Device according to any one of claims 1 to 8, characterized in that it comprises a heat exchanger (3) or an additional heat exchange portion arranged in series downstream of the two heat exchange portions and ensuring a heat exchange between the cryogenic fluid which has passed through the two heat exchange portions and a heat transfer fluid (32).

10. A method of heating a flow of cryogenic fluid, for example liquid hydrogen, using a heating device according to any one of claims 1 to 9, wherein, during a first step, a flow of cryogenic fluid to be heated is circulated in the first passages (12, 13) of the two heat exchange portions in series in a first order and a first direction of circulation and, simultaneously, a heating heat transfer fluid is circulated in the second passages (22, 23), the method comprising a step of reversing a flow of cryogenic fluid to be heated in the first passages (12, 13) of the two heat exchange portions in series, that is to say in a second order and second direction of circulation opposite respectively to the first order and first direction of traffic.

11. Method according to claim 10, characterized in that, during the first step, the flows of cryogenic fluid to be heated and of heating heat transfer fluid circulate in the same direction, that is to say co-currently in the first of the two heat exchange portions in series.

12. Method according to claim 10 or 11, characterized in that, during the first step, the flows of cryogenic fluid to be heated and of heating heat transfer fluid circulate in opposite directions, that is to say counter-currently in the second of the two heat exchange portions in series.

13. Method according to any one of claims 10 to 12, characterized in that the device is configured so that, at the outlet of the first of the two heat exchange portions in series, that is to say between the two heat exchange portions, the temperature of the cryogenic fluid is kept higher than the solidification temperature of the heat transfer fluid.

14. Method according to any one of claims 10 to 13, characterized in that the inversion step is triggered in response to the detection of at least one parameter representative of the appearance or risk of appearance of solidification of the heat transfer fluid in a heat exchange portion.

15. Method according to claim 14, characterized in that the at least one parameter representative of appearance comprises at least one of: a variation in flow rate of the heat transfer fluid, a variation in temperature of the cryogenic fluid and / or the heat transfer fluid, a temperature level of the cryogenic fluid and / or the heat transfer fluid, a variation in the pressure drop within the device.

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