Aeronautical gas distribution system

Abstract

Aeronautical Gas Distribution Device The invention relates to a method for supplying a hydrogen engine (200) comprising the following steps: - introducing a first volume of liquid hydrogen into an intermediate tank (120a, 120b); then - closing the intermediate tank; then - heating the intermediate tank until a distribution pressure and a distribution temperature are reached in the intermediate tank; then - supplying a hydrogen engine with the hydrogen contained in the intermediate tank until a cut-off temperature or a cut-off pressure is reached in the intermediate tank; then - closing the intermediate tank; then - purging the intermediate tank;The process is characterized in that the heating of the intermediate tank is maintained during the hydrogen engine supply stage with the hydrogen contained in the intermediate tank until the purge pressure is reached in the intermediate tank. Figure for the abstract: Fig. 1.;

Description

Title of the invention: Aeronautical gas distribution device technical field

[0001] The present description relates to a method for supplying a hydrogen engine. Previous technique

[0002] Hydrogen is increasingly being considered as an alternative to carbon fuel for mobility, particularly in aeronautics, partly due to the absence of carbon dioxide emissions during its combustion.

[0003] However, the large-scale use of hydrogen as a fuel requires solving certain existing problems, particularly concerning its storage and distribution.

[0004] For reasons of mass and size, hydrogen is generally stored in liquid form, and therefore at cold temperatures.

[0005] However, in order to be used in an engine, it then becomes essential to heat and pressurize the hydrogen.

[0006] Cryogenic device solutions exist in the literature, for example in applications FR 3133412 or WO 2022 / 263307.

[0007] However, even with such devices, power supply processes can still be improved, with the aim of reducing cost, increasing reliability or increasing the performance of the power supply circuit as a whole. Description of the invention

[0008] The object of the present invention is precisely to meet one, and ideally several, of these needs.

[0009] To this end, according to a first aspect thereof, the invention relates to a method for supplying a hydrogen engine comprising a supply cycle including at least the following steps: - the introduction into an intermediate tank of a first volume of liquid hydrogen at a feed temperature by establishing fluid communication between the intermediate tank and a main tank containing liquid hydrogen; then - the closure of the intermediate reservoir; then - heating the intermediate tank until a distribution pressure and temperature are reached in the intermediate tank; then - once the distribution pressure is reached in the intermediate tank, a hydrogen engine is supplied with the hydrogen contained in the tank intermediate until a cutoff temperature or cutoff pressure is reached in the intermediate tank; then - once the cut-off pressure or cut-off temperature is reached, the intermediate tank is closed; then - purging the intermediate tank by removing the remaining hydrogen until a purge pressure is reached in the intermediate tank; the process being characterized in that the heating of the intermediate tank is maintained during the stage of supplying the hydrogen engine with the hydrogen contained in the intermediate tank and this until the purge pressure is reached in the intermediate tank.

[0010] It is to the credit of the inventors that they identified that maintaining the heating of the intermediate tank, even after the engine has been supplied with hydrogen from said tank, made it possible to improve considerably and simultaneously several aspects compared with prior art hydrogen distribution methods.

[0011] In the processes usually envisaged in the prior art, the intermediate tank is put under very high pressure by a heating before being put into fluidic communication with the engine, and this until the pressure of the intermediate tank has decreased so much that it is no longer usable to supply the engine.

[0012] On the contrary, in a method of the invention, maintaining the heating of the intermediate tank during the step of supplying the engine with the hydrogen contained in the intermediate tank helps to maintain the pressure of the hydrogen in the intermediate tank or at least to allow the pressure of the hydrogen in the tank to fall less quickly than in the absence of heating.

[0013] In this way, on the one hand, the elements downstream of the cycle are confronted with lower pressures, which reduces the stresses applied to them and therefore increases their lifespan.

[0014] On the other hand, it is not necessary to achieve pressures in the intermediate reservoir as high as those of the prior art, because the pressure will remain above the determining threshold for supplying the engine for a longer period due to continuous heating.

[0015] Finally, the process reduces hydrogen losses during the purging step. Indeed, since the heating of the intermediate tank is maintained throughout the feeding step, at the time of purging, the gas will be at a higher temperature and pressure comparable to that of prior art processes, which ensures that less gas remains in the intermediate tank (for a given tank volume).

[0016] Throughout this application, reference will be made to hydrogen. It is understood that this formulation covers all gaseous and liquid forms of hydrogen commercially usable for the applications described, and in particular dihydrogen H2.

[0017] Although the present description only describes hydrogen for the sake of simplicity, it should be understood that the processes described can be applied to other fuels stored in cryogenic liquid form and used in gaseous form. Examples include methane, natural gas, and ammonia.

[0018] In one embodiment, the distribution pressure is less than or equal to 200 bars.

[0019] It is to the credit of the inventors that they determined that the use of a process such as described made it possible to reduce the distribution pressure in the intermediate tanks, which is usually between 400 and 700 bars in prior art distribution systems.

[0020] Reducing the distribution pressure helps to reduce the risks inherent in the use of pressurized equipment.

[0021] In addition, lowering the distribution pressure also reduces the resistance requirements of the intermediate tanks, and thus reduces their cost and mass, which is an advantage for any aeronautical application.

[0022] Indeed, prior art processes that required higher pressures in intermediate tanks subject all downstream components to significant pressures, known as "water hammer," when these intermediate tanks are opened. Avoiding these water hammers improves the service life of the device components and reduces safety constraints for all of these components.

[0023] In one embodiment, the distribution temperature is less than or equal to 400 K.

[0024] As with the distribution pressure, it is to the credit of the inventors that they have succeeded in determining that the distribution temperature could be lowered compared to the processes of the prior art.

[0025] In addition, the temperature of the gas distributed to the engine is much better regulated than in prior art processes thanks to the continuous heating of the intermediate tank.

[0026] Indeed, in prior art processes, the pressure variation in the intermediate tank is significant throughout the entire supply period, which generates a very significant temperature variation that requires the addition of temperature control devices before introducing hydrogen into the engine.

[0027] On the contrary, in the process of the invention, the temperature of the distributed gas is much more stable over time, which reduces the need for regulating devices.

[0028] In one embodiment, the cutoff temperature is less than or equal to 400 K, for example between 200 K and 400 K.

[0029] In one embodiment, the cutoff temperature may be greater than or equal to 200 K, or even greater than or equal to 250 K.

[0030] This cut-off temperature is identified as that which allows an acceptable loss of hydrogen. As described, once the cut-off temperature or cut-off pressure is reached, the engine supply is interrupted, and the intermediate tank is purged.

[0031] The remaining hydrogen is therefore lost. This means that even if the hydrogen is returned to the cryogenic reservoir, the actual quantity of dihydrogen used for a cycle is less than that of the dihydrogen introduced into the intermediate reservoir because the portion remaining in the reservoir at this stage of the cycle will not be used.

[0032] Put another way, for a given hydrogen supply requirement, the larger the system, the greater the proportion of hydrogen remaining at the end of the cycle. It is therefore desirable to reduce the proportion of hydrogen remaining at the end of the cycle to maximize the amount of useful hydrogen actually supplied to the engine in one cycle.

[0033] Choosing a cutoff temperature in accordance with that described above ensures less hydrogen loss at the end of the process.

[0034] In one embodiment, the cut-off pressure is less than or equal to 190 bars, or even less than or equal to 100 bars, for example between 50 bars and 100 bars.

[0035] It is to the credit of the inventors that they have succeeded in determining that the cut-off pressure could be comparable to those of prior art processes while ensuring that the maximum pressure reached in the intermediate tank during a feeding cycle is lower than in prior art processes.

[0036] In one method of the invention, it is described that the closure of the intermediate reservoir takes place once the cut-off pressure or cut-off temperature is reached.

[0037] It is understood by this expression that the supply of hydrogen to the engine contained in the intermediate tank is stopped at the first of the cut-off pressure or cut-off temperature reached.

[0038] Once the cut-off pressure or cut-off temperature is reached, the purging of the tank is initiated.

[0039] Purging the tank is understood as a step allowing the intermediate tank to be emptied of the hydrogen it contains once the engine supply has stopped.

[0040] This ensures that the filling of the intermediate tank for the next cycle can begin with an intermediate tank that is as empty as possible.

[0041] In one embodiment, the purge pressure is less than or equal to 3.0 bar, or even less than or equal to 2.0 bar, for example between 0.7 and 2 bar.

[0042] Such a purge pressure ensures that the intermediate reservoir is sufficiently empty to proceed with a new engine supply cycle.

[0043] In one embodiment, the first volume of hydrogen is between 50% and 95% of the volume of the intermediate tank.

[0044] For example, the first volume of hydrogen may be greater than or equal to 50% of the volume of the intermediate tank, or even greater than or equal to 75% of the volume of the intermediate tank, or even greater than or equal to 90% of the volume of the intermediate tank.

[0045] The inventors believe that such an embodiment makes it possible to carry out cycles where more hydrogen is present in the intermediate reservoir than in prior art processes.

[0046] Operating in this way takes the best of two extreme operating modes of the prior art. The first mode where the tank would be initially less full allows a higher distribution temperature to be reached, which ensures that there are few losses at the end of the cycle, but which does not allow a lot of dihydrogen to be delivered per cycle; the second mode where the tank is more full initially, but whose distribution temperature is lower and therefore lower at the end of the cycle, which leaves more dihydrogen unused.

[0047] The process of the invention allows the tank to be filled more than in the first embodiment where the temperature at the end of the cycle remains high while ensuring an initially high tank filling.

[0048] In addition, the proposed filling method reduces the number of cycles to be performed for the same quantity of hydrogen supplied to the engine at the same volume of the secondary tank.

[0049] In addition, the process allows working with a larger proportion of the cycle during which the tank is open compared to prior art cycles, which reduces wear on the entire supply circuit, and thus reduces the maintenance needs of the whole.

[0050] This advantage can also be viewed differently and considered as allowing, rather than supplying more hydrogen per fuel cycle, a reduction in size intermediate reservoirs compared to prior art processes, without reducing the amount of hydrogen supplied per cycle.

[0051] This results in a less bulky, and therefore lighter, installation, which represents an important advantage for aeronautical applications, for example.

[0052] In one embodiment, the process includes carrying out the steps described above in several intermediate tanks, which carry out feeding cycles in parallel and in which the cycles of each intermediate tank are out of phase with each other.

[0053] This embodiment makes it possible to ensure a more continuous supply of a hydrogen engine, since the intermediate tanks are never all at the same stage, and there is therefore at least one in distribution position.

[0054] This improves the operability of the entire hydrogen engine. Brief description of the drawings

[0055] [Fig-1] Fig. 1 schematically represents a device for putting into implements a method of implementing a process of the invention. Description of the implementation methods

[0056] The invention is now described by means of figures, which are present for descriptive purposes to illustrate certain embodiments of the invention and which should not be interpreted as limiting the latter.

[0057] Fig. 1 schematically represents a device enabling the supply of a hydrogen engine 200 by a process described above.

[0058] The following are visible in [Fig. 1]: - a main tank 100; - two intermediate tanks 120a, 120b; - a 200 hydrogen engine; - heating elements 140a, 140b.

[0059] The unnumbered features represent fluidic communications between the different elements.

[0060] Also shown on [Fig.1] is a set of valves and in particular: - a supply valve 110a (respectively 110b) allowing the fluidic communication of the main tank 100 with an intermediate tank 120a (respectively 120b); - a purge valve 150a (respectively 150b) allowing the opening of the intermediate tank 120a (respectively 120b) for purging the latter; - a distribution valve 130a (respectively 130b) allowing fluid communication of the intermediate tank 120a (respectively 120b) with the 200 engine, for supplying the latter with hydrogen from the intermediate tank.

[0061] Fig. 1 represents in dotted line a purge path from the intermediate reservoir 120a, 120b to the main reservoir 100.

[0062] This dotted path is meant to signify that there may be organs allowing the recovery of the purged hydrogen from the intermediate tank 120a, 120b, to the main tank, without needing to detail here what these organs might be.

[0063] In addition, and although they are not shown in [Fig.1], sensors, in particular pressure and temperature sensors, can be arranged on the whole device to allow determining whether one or the other of the valves 110a, 110b, 130a, 130b, 150a or 150b should be opened or closed.

[0064] Also, and although they are not shown in [Fig.1], each of the valves may have an actuating element controlling the opening or closing of said valve, the actuating element itself being able to be controlled by a central controller, for example a computer.

[0065] Preferably, the sensors described above can transmit the results of their measurements to the central controller, which then determines whether a valve 110a, 110b, 130a, 130b, 150a or 150b should be opened or closed.

[0066] For example, a feeding cycle is now described in connection with [Fig.1].

[0067] For the purposes of this example, we will consider here that the set of valves 110a, 110b, 130a, 130b, 150a and 150b is closed at the start of this cycle.

[0068] The cycle is described for the first intermediate reservoir 120a. It should be understood that the cycle can be identical for the second 120b, by simply changing the letters a to b in the reference signs associated with the elements.

[0069] However, it is preferable that the supply cycles for the first intermediate tank 120a and for the second intermediate tank 120b be carried out in opposite phase, that is to say that the cycle for the second intermediate tank 120b can start when the cycle of the first intermediate tank 120a reaches half of its duration.

[0070] It is thus ensured that at least one of the first 120a or the second intermediate reservoir 120b is in a position supplying the motor 200, which allows the latter to be supplied continuously.

[0071] An installation with two intermediate tanks 120a, 120b is described here, but it is by no means excluded that an installation may include several.

[0072] In one embodiment, it may be preferred that the feeding cycles carried out for each of the intermediate tanks be offset from the cycles of the others by an equal phase distance.

[0073] It is thus understood that if a duration t is required for the completion of a supply cycle and there are n intermediate reservoirs, a first reservoir begins its cycle at time 0, the second at time t / n, the third at 2t / n, and the nth at time (nl)t / n.

[0074] This ensures excellent continuity of supply to the engine with hydrogen from the intermediate tanks.

[0075] In one embodiment, the introduction into the first intermediate tank 120a of liquid hydrogen initially contained in the main tank 100 is permitted by opening the valve 110a.

[0076] This opening is maintained until the desired filling of the first intermediate tank 110a is reached. For example, it can be filled to more than 90% by volume, or even to more than 93% by volume, or even to more than 95% by volume.

[0077] Once the desired quantity of hydrogen has been introduced into the intermediate tank 120a, the tank 120a can be closed, by closing the valve 110a.

[0078] In one embodiment, the filling step just described can last between 10 seconds and 60 seconds.

[0079] The heating of the intermediate tank 120a can then begin by ignition of the heating means 140a.

[0080] Heating the intermediate tank 120a first causes the liquid hydrogen to change to its gaseous state, then causes a rise in temperature and pressure in the intermediate tank 120a.

[0081] This rise continues until the distribution pressure and distribution temperature are reached in the intermediate reservoir 120a.

[0082] This increase in pressure and temperature makes hydrogen available for the 200 engine, and in particular at a pressure and temperature in line with the specifications of the 200 hydrogen engine.

[0083] In one embodiment, the distribution pressure may be less than or equal to 200 bars, or even less than or equal to 100 bars.

[0084] The distribution pressure permitted by the processes described in this application is significantly lower than those of prior art processes.

[0085] This is made possible by the heating stage which will be maintained during the engine supply stage by the hydrogen contained in the intermediate tank.

[0086] This will be described in more detail below for the next step of supplying the hydrogen engine 200.

[0087] In one embodiment, the intermediate tank heating step can last between 5 seconds and 30 seconds.

[0088] In one embodiment, the distribution pressure may be greater than or equal to 20 bars, for example greater than or equal to 50 bars.

[0089] In one embodiment, the distribution pressure is between 50 bars and 100 bars.

[0090] Once the distribution pressure or distribution temperature is reached in the intermediate tank, the engine supply can begin, for example by opening valve 130a.

[0091] Opening the valve 130a causes the hydrogen engine 200 to be supplied due to the pressure of the hydrogen in the intermediate tank 120a.

[0092] However, and as described above, even after the opening of valve 130a, the heating of the intermediate tank 120a, via component 140a, is maintained.

[0093] Thus, although supplying the engine 200 with hydrogen present in the intermediate tank 120a causes the temperature of the latter to decrease due to the decrease in pressure in the intermediate tank 120a together with the decrease in the quantity of dihydrogen present in the intermediate tank 120a, maintaining the heating in the intermediate tank makes it possible to maintain the pressure in the intermediate tank, or at least to allow a much smaller decrease in pressure than if the heating were not maintained.

[0094] This ensures that the supply of the engine 200 can be maintained for much longer than if the heating of the intermediate tank 120a had been cut off, and above all at a much more stable pressure than in the usual alternative where the gas is expanded without maintaining the heating.

[0095] In addition, this allows the distribution pressure to be lowered because, since the pressure decreases little in the intermediate tank throughout the supply of the engine 200, it is not necessary for the initial pressure in the intermediate tank, i.e. the distribution pressure, to be too high.

[0096] Reducing the distribution pressure compared to prior art processes has many advantages. It reduces the need for intermediate tanks capable of withstanding very high pressures, thereby reducing their weight or size.

[0097] This also reduces the pressures seen downstream of the gaseous hydrogen utilization cycle. This results in greater durability of all the components of the feed system.

[0098] The supply of the engine 200 is thus continued until the heating element 140a can no longer compensate for the decrease in pressure, and the pressure in the intermediate tank reaches a cut-off pressure.

[0099] In one embodiment, this motor feeding step can last between 30 seconds and 5 minutes.

[0100] As indicated, the heater is maintained in the intermediate tank during the engine supply stage.

[0101] This heater makes it possible to maintain a pressure higher than the cut-off pressure in the tank for a maximum time, and to allow a continuous supply of the engine.

[0102] In one embodiment, the cut-off pressure corresponds to the minimum hydrogen pressure that the engine can use. In other words, in one embodiment, when the cut-off pressure is reached, the hydrogen in the intermediate tank can no longer be used to power the engine.

[0103] In one embodiment, once the cut-off pressure is reached in the intermediate tank 120a, the supply of hydrogen from the intermediate tank 120a to the engine 200 is interrupted by closing the valve 130a.

[0104] When the cut-off pressure is reached, the purging of the intermediate tank 120a can be carried out by opening the valve 150a.

[0105] Opening this valve allows the remaining hydrogen in the intermediate tank 120a to be evacuated.

[0106] In the embodiment shown, the dotted lines indicate that it is possible but not necessary for the purged hydrogen to be recovered and return to the main tank 100.

[0107] If necessary, components required for conditioning the purged hydrogen to return it to the main tank may be present, for example heat exchangers, pumps or other elements known for the application may be used.

[0108] The purging of the intermediate reactor 120a allows it to be emptied and ensures that it is in temperature and pressure conditions allowing the restart of the feed cycle.

[0109] In one embodiment, the purging of the intermediate tank 120a is undertaken until the pressure in the intermediate tank 120a is less than the purging pressure.

[0110] For example, the purging step can last between 5 seconds and 30 seconds.

[0111] The feeding cycle that has just been described and that was for the reservoir The intermediate 120a supply only allows intermittent power to the motor. However, this is sufficient for some applications.

[0112] However, when a continuous supply is desired, it is possible to arrange several intermediate tanks in parallel, as shown in the figure.

[0113] In this way, by phasing the supply cycles, that is to say by shifting them so that at least one of the tanks is always in a phase of supplying the engine.

[0114] Fig. 1 represents two intermediate reservoirs 120a and 120b, but this is by no means limiting, and there may be between 1 and 10 for example.

Claims

Demands

1. A method for supplying a hydrogen engine (200) comprising a supply cycle including at least the following steps: - introducing into an intermediate tank (120a, 120b) a first volume of liquid hydrogen at a supply temperature by fluidic communication of the intermediate tank with a main tank (100) comprising liquid hydrogen; then - closing the intermediate tank; then - heating the intermediate tank until a distribution pressure and a distribution temperature are reached in the intermediate tank; then - once the distribution pressure is reached in the intermediate tank, supplying a hydrogen engine with the hydrogen contained in the intermediate tank until a cut-off temperature or a cut-off pressure is reached in the intermediate tank;then - once the cut-off pressure or cut-off temperature is reached, the intermediate tank is closed; then - the intermediate tank is purged by removing the remaining hydrogen until a purge pressure is reached in the intermediate tank; the process being characterized in that the heating of the intermediate tank is maintained during the step of supplying the hydrogen engine with the hydrogen contained in the intermediate tank and this until the purge pressure is reached in the intermediate tank;

2. Method of supplying a hydrogen engine according to claim 1, wherein the distribution pressure is less than or equal to 200 bar.

3. Method of supplying a hydrogen engine according to claim 1 or 2, wherein the distribution temperature is less than or equal to 400 K.

4. Method of supplying a hydrogen engine according to any one of claims 1 to 3, wherein the cutoff temperature is greater than or equal to 250K.

5. Method of supplying a hydrogen engine according to any one of claims 1 to 4, wherein the cut-off pressure is less than or equal to 190 bar.

6. Method of supplying a hydrogen engine according to any one of claims 1 to 5, wherein the purge pressure is less than or equal to 3.0 bar.

7. Method of supplying a hydrogen engine according to any one of claims 1 to 6, wherein the first volume of hydrogen is between 50% and 95% of the volume of the intermediate tank.

8. Method of supplying a hydrogen engine according to any one of claims 1 to 7, wherein several intermediate tanks carry out supply cycles in parallel and wherein the cycles of each intermediate tank are out of phase with each other.

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