Optimized filling of cryogenic tanks

Abstract

A method for filling a plurality of receiving tanks with cryogenic liquid, using a plurality of mobile source tanks, the method comprising the following steps: transferring a first quantity of cryogenic liquid from a first source tank to a first receiving tank, and simultaneously transferring a first quantity of vaporization gas present in the first receiving tank to the first source tank; verifying that at least the distribution condition is met, the pressure in the first source tank is below a predetermined pressure threshold; if the distribution condition is met, transferring a second quantity of cryogenic liquid from the first source tank to a second receiving tank, and simultaneously transferring a second quantity of vaporization gas present in the second receiving tank to the first source tank. Abstract figure: Fig. 1

Description

Title of the invention: Optimized filling of cryogenic tanks

[0001] This invention relates to a method for filling cryogenic tanks. A cryogenic liquid is produced at a production site, optionally transported to storage sites, and then distributed to users at distribution sites. Most frequently, the production site includes storage tanks for the produced cryogenic liquid, from which mobile tanks are filled for distribution. Sometimes the cryogenic liquid is transported to storage sites, where the mobile tanks for distribution are filled.

[0002] At distribution sites, a receiving tank is filled with cryogenic liquid from a mobile tank originating at the production or storage site. The storage site can therefore also be considered a distribution site. Hereafter, a source tank is defined as any mobile cryogenic liquid tank from which a receiving tank is filled; a receiving tank is defined as any cryogenic liquid tank, fixed or mobile, that is filled with cryogenic liquid drawn from a source tank.

[0003] In some cases, the consumption of cryogenic liquid is so high that numerous source and receiving tanks must be managed at distribution sites. This is particularly true for cryogenic liquids used as fuels. Distribution sites must then be able to manage multiple source and receiving tanks, while optimizing filling procedures and ensuring the safety of equipment and personnel. When the cryogenic liquid is used as a fuel, the issue of eliminating, or at least limiting, greenhouse gas emissions also arises, particularly those caused by venting the evaporation gases contained in the tanks.

[0004] Examples of distribution sites include vehicle fuel tank filling sites, such as land vehicle fuel filling stations, railway stations and airports, and boat and ship fuel tank filling sites.

[0005] The desire to use liquid hydrogen as a fuel, in order to address the challenges of climate change, leads to specific constraints related to its characteristics and its use. The main problems that arise These challenges are related to the cryogenic nature of liquid hydrogen and the retention time of cryogenic liquid tanks, particularly mobile ones. Due to heat input to the tanks, some of the cryogenic liquid evaporates, generating boil-off gas (BOG). Over time, the generation of this boil-off gas leads to a decrease in the cryogenic liquid level within the tank, as well as a rise in the pressure and temperature of the cryogenic liquid. This can pose a problem for ensuring that receiving tanks are filled under optimal conditions, that is, under thermodynamic conditions that allow for the exploitation and use of the maximum quantity of cryogenic liquid, ideally all of it.

[0006] In the specific case of vehicle refueling sites, and particularly airports, it is likely impossible, for safety reasons, to depressurize the receiving tank (e.g., of an aircraft, car, truck, or train) or the source tank at the same location where refueling operations are carried out (e.g., on the airport tarmac, in the car or truck parking area, or at a train station). It is known that a dedicated area for depressurization operations can be provided to avoid this problem.

[0007] It is also known to use, instead of source tanks, a network of distribution lines to distribute the cryogenic liquid and recover the evaporation gases. An example is described in G.D. Brewer's study, "LH2 Airport Requirements Study," published by NASA in 1976. These systems are expensive to build and offer little flexibility in their operation.

[0008] It is also known, for vehicle fuel tanks, to replace an empty tank with a full one. These solutions require the use of a larger number of tanks and the establishment of dedicated tank exchange sites, which are more complicated to manage than filling sites.

[0009] The object of the present invention is to propose a method and a system for filling cryogenic liquid tanks which overcomes all or part of the disadvantages mentioned above.

[0010] The invention relates in particular to a method for filling a plurality of receiving tanks with cryogenic liquid, in particular liquid cryogenic fuel tanks for vehicles, the cryogenic liquid being in particular liquid hydrogen. The method uses a plurality of mobile source tanks. The method comprises the following steps.

[0011] Transfer of a first quantity of cryogenic liquid from a first source reservoir to a first receiving reservoir, and simultaneous transfer of a first quantity of vaporization gas present in the first receiving reservoir to the first source reservoir.

[0012] Verification of at least the distribution condition that the pressure in the first source reservoir is less than a predetermined pressure threshold.

[0013] If the distribution condition is met, transfer of a second quantity of cryogenic liquid from the first source reservoir to a second receiving reservoir, and simultaneous transfer of a second quantity of vaporization gas present in the second receiving reservoir to the first source reservoir.

[0014] The invention can advantageously be applied to the filling of fixed or mobile receiving tanks, in particular semi-trailers for transporting liquefied gases, or onboard cryogenic fuel tanks. The fluids concerned are, for example, helium, hydrogen, methane, natural gas, or any other fluid or mixture of fluids at cryogenic temperatures.

[0015] According to other aspects, embodiments of the invention may include one or more of the following features.

[0016] In one embodiment, at least a fraction of the first quantity of vaporization gas is reliquefied in the first source reservoir and the first quantity of cryogenic liquid comprises at least a first part of the reliquefied fraction of vaporization gas.

[0017] In one embodiment, the verification further includes verifying the condition that the liquid level in the first source tank is above a predetermined liquid level threshold, the distribution condition relating to the liquid level in the source tank being preferably verified before the distribution condition relating to the pressure in the first source tank.

[0018] In one embodiment, the second quantity of cryogenic liquid comprises at least a second part of the fraction of the first quantity of vaporization gas that is reliquefied.

[0019] In one embodiment, the method includes the additional steps of transferring a third quantity of cryogenic liquid from a second source reservoir to the second receiving reservoir, and simultaneously transferring a third quantity of vaporization gas present in the second receiving reservoir to the second source reservoir, the third quantity of vaporization gas comprising at least a portion of the second quantity of vaporized cryogenic liquid.

[0020] In one embodiment, when the liquid level in the source tank is above the predetermined liquid level threshold but the pressure in the source tank is not below the predetermined pressure threshold, the method includes a step of depressurizing the source tank before the step of transferring the quantity of cryogenic liquid.

[0021] In one embodiment, the method uses a tractor vehicle to establish a fluidic connection between the source tank and the receiving tank, at least one distribution condition being verified via at least one pressure and / or liquid level measuring device, installed on the source tank and / or on the tractor vehicle.

[0022] In one embodiment, the tractor vehicle and / or the source tank(s) include a pump configured to allow pumping of the cryogenic liquid during the cryogenic liquid transfer step.

[0023] In one embodiment, the receiving tanks are liquid cryogenic aircraft fuel tanks and the method is implemented within the perimeter of an airport.

[0024] In one embodiment, the steps of transferring a first quantity of liquid, checking, and transferring a second quantity of liquid are executed in series, in that order, and are preceded by the following preliminary steps.

[0025] Establishment of a mechanical connection between the first source tank and the tractor vehicle, in a first area of ​​the airport intended for the parking of the source tanks and the tractor vehicle.

[0026] Movement, using the tractor vehicle, of the first source tank and the tractor vehicle to a second area of ​​the airport, intended for filling the plurality of receiving tanks.

[0027] Establishing a fluidic connection between the first receiving reservoir and the first source reservoir via the tractor vehicle.

[0028] The fluid connection between the first receiving tank and the first source tank via the refueling vehicle is interrupted before at least one cryogenic liquid distribution condition is verified. If the distribution condition is not met, the first source tank and the towing vehicle are moved to the first airport zone using the towing vehicle.

[0029] Other features and advantages will become apparent from the following description, made with reference to the following figures.

[0030] Fig. 1 represents schematically and partially a first example of a filling method according to the invention.

[0031] Fig. 2 schematically and partially represents a second example of a filling method according to the invention.

[0032] Fig. 3 represents a schematic and partial view illustrating a first example of a system for implementing a method according to the invention.

[0033] Fig. 4 is a schematic and partial view illustrating a second example of a system for implementing a method according to the invention.

[0034] Fig. 5 represents a schematic and partial view, illustrating an example of a possible embodiment of a method according to the invention.

[0035] The filling method shown schematically in [Fig. 1] and [Fig. 5] allows a plurality of receiving reservoirs 11, 12, 13, 14 to be filled with cryogenic liquid and uses a plurality of mobile source tanks 21, 22, 23 and a tractor vehicle 30. The source tanks and receiving tanks are typically configured to contain a liquid phase and a vapor phase of the cryogenic liquid.

[0036] The method can be implemented, for example, as shown in [Fig.3] and [Fig.4], in a distribution site comprising a first zone 1 for parking the source tanks 21, 22, 23 and a second zone 2, separate from the first zone 1, for filling the receiving tanks 11, 12, 13, 14.

[0037] The first zone 1 is specifically designed to accommodate full source tanks from a production or storage site 3, which may be located more than 100 km from the distribution site. This distance will depend on the characteristics of the cryogenic liquid to be distributed. In the case of liquid hydrogen, it is typically around 200 km. Site 3 may, for example, be a liquefier or an intermediate storage site.

[0038] The second zone 2 is intended to house the receiving tanks, and it is here that the filling operations for the receiving tanks take place. Within the distribution site, the second zone 2 is separated from the first zone 1. For example, users or owners of the receiving tanks have access only to the second zone 2 and not to the first zone 1.

[0039] Source tanks 21, 22, 23 are used to transport the cryogenic liquid from the production or storage site 3 to the distribution site. The source tank is a mobile tank and preferably mounted on a semi-trailer towed by a motor vehicle 40. The source tank can also be installed directly on a motor vehicle.

[0040] One or more tractor vehicles 30 may be provided at the distribution site to tow the mobile source tanks within the distribution site, and in particular to the second zone 2. The tractor vehicles 30 may be the same motorized vehicles 40 used to tow the source tanks 21, 22, 23 from the production or storage site 3 to the distribution site. The tractor vehicles 30 may also be dedicated motorized vehicles 30, which are permanently stationed at the distribution site. Within the first zone 1, the tractor vehicles 30 may be coupled to a source tank, or they may be uncoupled and parked separately from the source tanks.

[0041] The method includes a transfer step 110 of a first quantity 51 of cryogenic liquid from a first source reservoir 21 to a first receiving reservoir 11. Preferably, during the transfer step 110 of the first quantity 51 of cryogenic liquid, a first quantity 61 of evaporation gas present in the first receiving reservoir 11 is simultaneously transferred to the first source reservoir 21.

[0042] The method includes a verification step 120. We verify at least the distribution condition 121, 122, 123 that the pressure in the first source tank 21 is less than a predetermined pressure threshold.

[0043] When the distribution condition is met, in particular if the pressure measured in the first source tank 21 is below the predetermined pressure threshold, the method includes a transfer step 110 of a second quantity 52 of cryogenic liquid from the first source tank 21 to a second receiving tank 12. Preferably, during the transfer step 110 of the second quantity 52 of cryogenic liquid, a second quantity 62 of vaporization gas present in the second receiving tank 12 is simultaneously transferred to the first source tank 21.

[0044] In one embodiment, at least a fraction of the first quantity of vaporization gas 61 is reliquefied in the first source reservoir 21, and the first quantity 51 of cryogenic liquid comprises at least a first part of the reliquefied fraction of vaporization gas. The mass of liquid delivered to the first receiving reservoir is optimized.

[0045] The liquefaction, at least partial, of the evaporation gases injected into the first source reservoir can be obtained by controlling for this purpose the thermodynamic conditions inside the first source reservoir, or the injection conditions of the evaporation gas into the first source reservoir.

[0046] In one embodiment, the verification step 120 further includes verifying that the liquid level 121 in the first source tank 21 is above a predetermined liquid level threshold. Preferably, the distribution condition relating to the liquid level 121 in the source tank 21, 22 is verified before the distribution condition relating to the pressure 122 in the first source tank 21. The decision to fill or not fill the second receiving tank is more efficient, and the management of refills at the distribution site is optimized.

[0047] In one embodiment, the second quantity 52 of cryogenic liquid comprises at least a second portion of the reliquefied fraction of the first quantity of vaporization gas 61. The quantity of cryogenic liquid actually delivered to the distribution site is maximized, losses due to vaporization gases are reduced, and the mass of liquid delivered to the second receiving tank is optimized.

[0048] In one embodiment, the method includes an additional step 110 of transferring a third quantity 53 of cryogenic liquid from a second source reservoir 22 to the second receiving reservoir 12. Preferably, during the transfer step 110 of the third quantity 53 of cryogenic liquid, a third quantity 63 of vaporization gas present in the second reservoir The vapor from receiver 12 is simultaneously transferred to the second source tank 22. The third quantity 63 of vaporization gas includes at least a portion of the second quantity 52 of vaporized cryogenic liquid. Recovery of the vaporization gases is ensured, and the quantity of cryogenic liquid actually delivered to the distribution site is maximized.

[0049] In one embodiment, when the liquid level 121 in the source tank 21, 22 is above the predetermined liquid level threshold but the pressure 122 in the source tank 21, 22 is not below the predetermined pressure threshold, the method includes an additional depressurization step 132 of the source tank 21, 22 before the transfer step of the quantity 51, 52, 53 of cryogenic liquid. The cryogenic liquid in the source tank 21, 22 is thus brought back to thermodynamic conditions favorable for its delivery and / or use. The quantity of cryogenic liquid actually delivered to the distribution site is maximized.

[0050] Depending on the nature of the distribution site, the depressurization step can be carried out in a different suitable area. Preferably, in the case of an airport, a railway station or similar sites, the depressurization is carried out in the first zone 1.

[0051] In one embodiment, the method uses the tractor vehicle 30 to establish a fluid connection between the source tank 21, 22 and the receiving tank 11, 12. At least one distribution condition 120, 121, 122, 123 is then checked via at least one pressure and / or liquid level measuring device, installed on the source tank 21, 22, 23 and / or on the tractor vehicle 30.

[0052] More generally, at least one distribution condition 120, 121, 122, 123 can always be checked via at least one pressure and / or liquid level measuring device, installed on the source tank 21, 22, 23.

[0053] In one embodiment, the tractor vehicle 30 and / or the source tank(s) 21, 22, 23 include a pump configured to pump the cryogenic liquid during the cryogenic liquid transfer step 110. The thermodynamic efficiency of the transfer is improved. The transferred flow rate can be controlled more flexibly, for example, in real time.

[0054] In one embodiment, the receiving tanks 11, 12, 13 are liquid cryogenic aircraft fuel tanks and the method is implemented within the perimeter of an airport 1, 2.

[0055] The steps of transferring a first quantity of liquid 51, of checking 120, of transferring a second quantity of liquid 52 can be carried out, in series, in this order.

[0056] Prior to the execution of these steps in the second zone 2 of the airport, a step of establishing a mechanical connection between the first source tank 21 and the tractor vehicle 30 can be carried out in the first zone 1 of the airport.

[0057] The movement 101, 102 can then be carried out, using the tractor vehicle 30, the first source tank 21 and the tractor vehicle 30 towards the second zone 2 of the airport.

[0058] Finally, in the second zone 2, a step can be carried out to establish a fluidic connection between the first receiving tank 11 and the first source tank 21 via the tractor vehicle 30.

[0059] Preferably, the fluid connection 41 between the first receiving tank 11 and the first source tank 21 via the refueling vehicle 30 is interrupted before the check 120 of at least one cryogenic liquid distribution condition. If the distribution condition 121, 122, 123 is not met, the first source tank 21 and the towing vehicle 30 can then be moved to the first zone 1 of the airport, using the towing vehicle 30.

[0060] In one embodiment, the method comprises, in series and in order, the following steps.

[0061] Establishment 103 of a fluidic connection 40, 41 between a first receiving tank 11 and a first source tank 21 via the supply vehicle 30.

[0062] Transfer 110 of a first quantity 51 of liquid cryogenic fuel from the first source tank 21 to the first receiving tank 11 via the refueling vehicle 30, and simultaneous transfer of a first quantity 61 of vaporization gas present in the first receiving tank 11 to the first source tank 21 via the refueling vehicle 30.

[0063] Verification 120 of at least one condition 121, 122, 123 of distribution of the liquid cryogenic fuel, in particular that the pressure in the first source tank 21 is below a predetermined pressure threshold.

[0064] If at least one fuel distribution condition is met, a fluid connection 40, 42 is established 103 between a second receiving tank 12 and the first source tank 21 via the refueling vehicle 30, then a second quantity 52 of liquid cryogenic fuel is transferred 110 from the first source tank 21 to the second receiving tank 12 via the refueling vehicle 30, and simultaneously a second quantity 62 of vaporization gas present in the second receiving tank 12 is transferred to the first source tank 21 via the refueling vehicle.

[0065] In one embodiment, the tractor vehicle 30 comprises a fluid circuit equipped with a set of valves, pipes, and fluid control devices such as a pump or compressor. The tractor vehicle 30 may also include an electronic controller, or other equivalent device, configured to control at least some of the valves, pipes and control devices in order to execute a method according to the invention.

[0066] In one embodiment, a fluidic and / or mechanical connection is established between the source tank and the tractor vehicle 30 in the second zone 2, near the receiving tank.

[0067] In one embodiment, the fluidic and / or mechanical connection is established between the source tank and the tractor vehicle 30 in the first zone 1 or in a third zone of the distribution site, at a distance from the receiving tank.

[0068] In one embodiment, the source tanks are configured to receive and store the cryogenic liquid in a subcooled state. A liquid is in a subcooled state when its temperature is below the saturation temperature corresponding to the pressure at which the liquid is located, or its pressure is above the saturation pressure corresponding to the temperature at which the liquid is located.

Claims

Demands

1. A method for filling a plurality of receiving tanks (11, 12, 13, 14) with cryogenic liquid, in particular with liquid cryogenic fuel tanks for vehicles, the cryogenic liquid being in particular liquid hydrogen, the method using a plurality of movable source tanks (21, 22, 23), the method comprising the following steps: - Transfer (110) of a first quantity (51) of cryogenic liquid from a first source tank (21) to a first receiving tank (11), and simultaneous transfer of a first quantity (61) of vaporization gas present in the first receiving tank (11) to the first source tank (21); - Verification (120) of at least the distribution condition (121, 122, 123) that the pressure in the first source tank (21) is less than a predetermined pressure threshold;- If the distribution condition is met, transfer (110) of a second quantity (52) of cryogenic liquid from the first source reservoir (21) to a second receiving reservoir (12), and simultaneous transfer of a second quantity (62) of vaporization gas present in the second receiving reservoir (12) to the first source reservoir (21).;

2. Method according to claim 1, characterized in that at least a fraction of the first quantity of vaporization gas (61) is reliquefied in the first source reservoir (21) and in that the first quantity (51) of cryogenic liquid comprises at least a first part of the reliquefied vaporization gas fraction.

3. Method according to claim 2, characterized in that the second quantity (52) of cryogenic liquid comprises at least a second part of the fraction of the first quantity of vaporization gas (61) reliquefied.

4. A method according to any one of claims 1 to 3, characterized in that the verification (120) further comprises verifying the condition that the liquid level (121) in the first source tank (21) is above a predetermined liquid level threshold, the distribution condition relating to the liquid level (121) in the source tank (21, 22) preferably being verified before the pressure-related distribution condition (122) in the first source reservoir (21).

5. Method according to claim 4, characterized in that, when the liquid level (121) in the source tank (21, 22) is above the predetermined liquid level threshold but the pressure (122) in the source tank (21, 22) is not below the predetermined pressure threshold, the method includes a depressurization step (132) of the source tank (21, 22) before the step of transferring the quantity (51, 52, 53) of cryogenic liquid.

6. A method according to any one of claims 1 to 5, characterized in that it comprises the additional steps of transferring (110) a third quantity (53) of cryogenic liquid from a second source tank (22) to the second receiving tank (12), and of simultaneously transferring a third quantity (63) of vaporization gas present in the second receiving tank (12) to the second source tank (22), the third quantity (63) of vaporization gas comprising at least a portion of the second quantity (52) of vaporized cryogenic liquid.

7. Method according to any one of claims 1 to 6, characterized in that it uses a tractor vehicle (30) to establish a fluidic connection between the source tank (21, 22) and the receiving tank (11, 12), at least one distribution condition (120, 121, 122, 123) being checked via at least one pressure and / or liquid level measuring device, installed on the source tank (21, 22, 23) and / or on the tractor vehicle (30).

8. Method according to claim 7, characterized in that the tractor vehicle (30) and / or the source tank(s) (21, 22, 23) comprise a pump configured to allow pumping of the cryogenic liquid during the cryogenic liquid transfer step (110).

9. Method according to any one of claims 1 to 8, characterized in that the receiving tanks (11, 12, 13, 14) are liquid cryogenic aircraft fuel tanks and in that the method is implemented within the perimeter of an airport (1,2).

10. Method according to claim 9, characterized in that the steps of transferring (110) a first quantity of liquid, checking (120), transferring (110) a second quantity of liquid are executed sequentially, in this order, and preceded by the following preliminary steps: - establishment of a mechanical connection between the first source tank (21) and the tractor vehicle (30), in a first area (1) of the airport intended for the parking of the source tanks and the tractor vehicle; - movement (101, 102), using the tractor vehicle (30), of the first source tank (21) and the tractor vehicle (30) to a second area (2) of the airport, intended for filling the plurality of receiving tanks (11, 12, 13); - establishment of a fluidic connection between the first receiving reservoir (11) and the first source reservoir (21) via the tractor vehicle (30); - and in that the fluidic connection (41) between the first receiving tank (11) and the first source tank (21) via the refueling vehicle (30) is interrupted before the verification (120) of at least one condition of distribution of the cryogenic liquid; and, if the condition (121, 122, 123) of distribution is not met, the first source tank (21) and the tractor vehicle (30) being moved into the first area (1) of the airport, using the tractor vehicle (30).

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