METHOD AND SYSTEM FOR PRESSURIZING GASIFIED HYDROGEN

Description

FIELD OF INVENTION

[0001] The present invention relates to a method and system for pressurizing gaseous hydrogen. STATE OF THE ART

[0002] A gaseous hydrogen storage and distribution system for fuel cell vehicles must be able to fill tanks at a pressure of 350 or 700 bar or more.

[0003] In such a system, liquid hydrogen is typically injected into an expansion tank. Since the walls of the expansion tank are at a higher temperature than the liquid hydrogen, the hydrogen vaporizes instantly. Consequently, the pressure inside the tank increases rapidly, making refilling with liquid difficult.

[0004] Filling such a pressurized tank is typically done from a gaseous hydrogen storage tank by compressing the gaseous hydrogen with several compression stages, each requiring a gas compressor. Installing the different pressure levels is complex and expensive.

[0005] Another technique involves using a high-pressure liquid compressor. Such a compressor, designed to withstand high intermediate pressures, is also a complex and expensive component.

[0006] Documents EP 3 653922A1, DE 102011108147A1, WO 2015125585 A1 and DE 100 37163A1 describe known gaseous hydrogen compression and / or filling systems. DESCRIPTION OF THE INVENTION

[0007] One object of the invention is to provide a pressurization and cooling process and system for a gaseous hydrogen filling station capable of compressing gaseous hydrogen to pressures above 200 bar from a gaseous hydrogen reservoir.

[0008] To this end, the invention proposes a method for pressurizing gaseous hydrogen comprising the following steps: the provision of a first tank suitable for receiving pressurized gaseous hydrogen, the filling of the first tank (1) with gaseous hydrogen compressed to a first pressure, the cooling of the compressed gaseous hydrogen contained in the first tank (1) to a first cryogenic temperature, the transfer by pressure balancing of a portion of the gaseous hydrogen at said first cryogenic temperature of said first tank (1) to at least a second tank (2), the hermetic sealing of at least a second tank containing the hydrogen transferred from the first tank, the increase of the pressure in the second tank by heating the hydrogen present in the second tank to a second temperature higher than the first temperature.

[0009] The system does not use liquid hydrogen.

[0010] In some embodiments, the hydrogen gas is cooled to the first temperature in the first tank. Preferably, the first tank is cooled by a cryogenic fluid. The cryogenic fluid is liquid nitrogen, liquid methane, or liquefied natural gas.

[0011] In other embodiments, the gaseous hydrogen is cooled to the first temperature by a heat exchanger arranged upstream of the first tank. In these embodiments, the first tank includes thermal insulation.

[0012] Preferably, the maximum pressure in the first tank is between 500 and 600 bar. The maximum pressure in at least one second tank is between 1000 and 1500 bar.

[0013] Advantageously, at least one second tank has a smaller volume than the first tank. Particularly advantageously, the volume of at least one second tank is between 40% and 60% of the volume of the first tank.

[0014] Advantageously, the second temperature range is between -40°C and 25°C.

[0015] In some embodiments, the process of pressurizing gaseous hydrogen includes a heating step in at least a second tank.

[0016] In some embodiments, a second tank is a vehicle tank.

[0017] The invention also relates to a hydrogen pressurization system comprising: a first tank adapted to receive pressurized gaseous hydrogen, a cooling device suitable for cooling the gaseous hydrogen to a first cryogenic temperature, a gas compressor suitable for compressing gaseous hydrogen upstream of said first tank, a fluid connection suitable for selectively establishing a fluid connection between the first tank and a second tank so as to transfer pressurized gaseous hydrogen at the first cryogenic temperature from the first tank to the second tank by pressure balancing, said second tank being suitable for being hermetically sealed and for being at a second temperature higher than the first temperature of the first tank.

[0018] In some embodiments, the first reservoir is immersed in the cryogenic fluid at the first temperature.

[0019] In other embodiments, the first tank includes conduits suitable for containing the cryogenic fluid so as to cool the first tank to the first temperature. Preferably, the system includes thermal insulation arranged on the outside of the conduits.

[0020] In other embodiments, the cooling device is a heat exchanger arranged upstream of the first tank.

[0021] Advantageously, at least one second tank includes a heating device. Particularly advantageously, the heating device includes conduits arranged for the circulation of a gas at a temperature equal to or greater than the second temperature. Preferably, the gas is nitrogen or helium.

[0022] Advantageously, at least one second tank also includes a thermal insulation device.

[0023] The invention also relates to a vehicle refueling station using gaseous hydrogen, comprising a hydrogen pressurization system, at least one second tank being a vehicle tank to be refueled with gaseous hydrogen. BRIEF DESCRIPTION OF THE FIGURES

[0024] Other features and advantages of the invention will become apparent from the detailed description that follows, with reference to the attached drawings, in which: There figure 1 is a diagram of the first part of the pressurization system. figure 2 is a diagram of an alternative embodiment of the first part of the pressurization system. figure 3 is a diagram of one embodiment of the second part of the pressurization system. figure 4 is a diagram of a second embodiment of the second part of the pressurization system. figure 5is a diagram of a third embodiment of the second part of the pressurization system. DETAILED DESCRIPTION OF IMPLEMENTATION METHODS

[0025] There figure 1 illustrates an embodiment of a first part of a gaseous hydrogen pressurization system according to the invention.

[0026] Such a system comprises a first reservoir 1 having a first volume, adapted to receive pressurized gaseous hydrogen. The system further comprises a cooling device capable of cooling the gaseous hydrogen contained in said first reservoir 1 to a first temperature which is typically between 75 K and 115 K. Advantageously, the first reservoir 1 is cooled by a cryogenic fluid 30 which is, for example, liquid nitrogen, liquid methane, or liquefied natural gas.

[0027] In some embodiments, the first reservoir is immersed in the cryogenic fluid 30 at the first temperature in a cryostat 3.

[0028] Alternatively, the first tank 1 includes conduits suitable for containing the cryogenic fluid so as to cool the first tank 1 to the first temperature. Said first tank 1 may include thermal insulation arranged on the outside of the conduits or the cryostat.

[0029] According to other embodiments, with reference to the figure 2 The cooling device is a heat exchanger 72 arranged upstream of the first tank. Said heat exchanger 72 is in heat exchange with a cryogenic liquid 73 in a cryostat 71. Preferably, the heat exchanger is immersed in the cryogenic liquid 73. Said cryogenic liquid is, for example, liquid nitrogen, liquid methane, or liquefied natural gas.

[0030] In some embodiments, the first tank 1 includes thermal insulation 9 suitable for thermally insulating the first tank 1 and / or the cooling device.

[0031] The gaseous hydrogen pressurization system further includes a gas compressor 4 adapted to compress gaseous hydrogen in said first tank from a gaseous hydrogen source. Said gaseous hydrogen source is typically a storage tank 5 containing pressurized gaseous hydrogen 8, typically between 20 and 200 bar. Alternatively, the gaseous hydrogen source is an electrolyzer, the hydrogen being at a pressure between 20 and 50 bar. The gaseous hydrogen 8 is at a second temperature higher than the first temperature. Typically, the second temperature is close to ambient temperature, which is approximately 230 K - 330 K.

[0032] The system further includes conduits 54, 43 arranged to establish a fluidic link between the gaseous hydrogen source 5, the gas compressor 4 and the first tank 1 so as to transfer pressurized gaseous hydrogen from the gaseous hydrogen source to the first tank 1. The system includes at least one valve 11 suitable for hermetically sealing the tank 1.

[0033] With reference to the figure 3 The gaseous hydrogen pressurization system further includes a second reservoir 2 having a third temperature higher than the first temperature. The third temperature is typically between 230 K and 330 K. In some embodiments, the third temperature is the same as the second temperature.

[0034] The second tank 2 may include a heating device. By way of illustration and without limitation, said heating device may include conduits arranged for the circulation of a gas at a temperature greater than or equal to the second temperature. Preferably, said gas is nitrogen or helium. When the second tank 2 includes a heating device, said second tank 2 advantageously includes thermal insulation capable of maintaining the hydrogen present in said second tank 2 at the third temperature.

[0035] Advantageously, said second tank 2 has a second volume that is less than the first volume of the first tank 1. According to an illustrative and non-limiting example, the volume of the second tank 2 can be between 40% and 60% of the volume of the first tank 1.

[0036] The system further includes a conduit 12 arranged to establish a fluidic link between the first tank 1 and the second tank 2 so as to transfer pressurized gaseous hydrogen from the first tank 1 to the second tank 2 by pressure balancing, and a valve 22 arranged to hermetically close said second tank 2.

[0037] Such a system can be used in a vehicle refueling station using gaseous hydrogen.

[0038] In one embodiment, with reference to the figure 4 , the second tank 2 is a vehicle tank to be filled with gaseous hydrogen.

[0039] In some embodiments, with reference to the figure 5Additional tanks are added to achieve multiple compression stages. In this case, the system includes several secondary tanks 2A, 2B, 2C, 2D. The number of secondary tanks is given for illustrative purposes only and is not a limitation. The number of secondary tanks 2A, 2B, 2C, 2D is typically between 2 and 5 and may be higher in some embodiments.

[0040] The number of second 2A-2D tanks depends on the capacity of the tanks, the space available, and the usage cycle of the pressurization system, including the amount of hydrogen to be distributed and the number of daily refills, the maximum pressures of the tanks to be filled (350 or 700 bar or another pressure), the choice of maximum permissible pressures in the second 2A-2D tanks and the effective pressure remaining in the tanks to be filled.

[0041] The volume of each second tank 2A, 2B, 2C, 2D is preferably less than the volume of the first tank 1, but may be the same. Alternatively, at least two tanks may have different volumes.

[0042] The system further includes a conduit 12A, 12B, 12C, 12D, arranged to establish a fluidic link between the first tank 1 and the respective second tank 2A-2D, so as to transfer pressurized gaseous hydrogen from the first tank 1 to the second tank 2 by pressure balancing, and a valve 22A, 22B, 22C, 22D arranged to hermetically close the respective second tank 2A-2D.

[0043] Each of the 2A-2D tanks has a third temperature that is higher than the first temperature. This third temperature is typically between 230 K and 330 K. The third temperature may be the same as the second temperature. In some embodiments, the third temperature of each 2A-2D tank is identical. Alternatively, at least two 2A-2D tanks may have different temperatures.

[0044] Each second tank 2A-2D may include a heating device. By way of illustration and without limitation, said heating devices may include conduits arranged for the circulation of a gas at a temperature greater than or equal to the second temperature. Preferably, said gas is nitrogen or helium. When at least one second tank 2A-2D includes a heating device, the respective second tank 2A-2D advantageously includes thermal insulation suitable for maintaining the hydrogen present in said second tank 2A-2D at the third temperature. When the system includes several second tanks 2A-2D, said system further includes a gas compressor 7 arranged to draw gaseous hydrogen from one tank 2A-2D and compress said gaseous hydrogen in another of the tanks 2A-2D via conduits 27A-27D and valves 77A-77D.

[0045] We will now describe the process of hydrogen pressurization by a gaseous hydrogen pressurization system as described above.

[0046] The first step consists of transferring gaseous hydrogen 8 from a gaseous hydrogen source 5 into the first tank 1, by compressing said gaseous hydrogen 8 via the gas compressor 4. The gaseous hydrogen is cooled to the first temperature during filling, either inside the first tank 1, or via a cooling device arranged upstream of the first tank 1. At the end of said first step, the first tank 1 is filled with gaseous hydrogen at the first temperature at a first pressure which is typically between 500 and 600 bar.

[0047] When filling is complete, valve 11 is closed to cut off the fluidic link between the liquid hydrogen source and to hermetically seal the first tank 1.

[0048] Subsequently, valve 22 is opened, and some of the hydrogen gas from the first tank 1 is transferred to the second tank 2 by pressure equalization. During this step, the transferred hydrogen gas is at a temperature close to that of the first tank. When the second tank 2 has a smaller volume than the first tank 1, the pressure after the transfer step remains high, thus increasing the efficiency of the pressurization system.

[0049] When the pressures of the first tank 1 and the second tank 2 are equal to an equilibrium pressure, the valve 22 is closed, thus hermetically sealing the second tank 2. The hydrogen gas transferred into the second tank 2 is heated to the third temperature of the second tank 2. The heating can be carried out by heat exchange with the environment, or by a heating device.

[0050] The energy provided by the environment, which is warmer than the gaseous hydrogen, allows for the self-pressurization of the gaseous hydrogen in the second tank 2. The gaseous hydrogen in the second tank 2 is then at a second pressure that is higher than the first pressure in the first tank 1 and higher than the equilibrium pressure. This second pressure is typically between 1000 and 1500 bar.

[0051] The pressurized gaseous hydrogen in the second tank 2 can then be used for filling one or more fuel cell vehicles (tank 2 can itself be a tank of the vehicle) or for other applications.

[0052] If the second tank 2 is a vehicle's fuel tank, the second pressure is typically 700 bar, according to current standards. The hydrogen can then be used directly in the vehicle. Higher pressure values ​​may be achieved and implemented should standards for fuel cell vehicles evolve.

[0053] In the case where the system includes several second tanks 2A, 2B, 2C, 2D, each second tank 2A-2D is filled from the first tank as described above.

[0054] The pressurized gas in the second 2A-2D tanks can then be used to supply a pressurized hydrogen gas application. This supply is achieved by pressure equalization between one or more of the 2A-2D tanks and the tank of the application to be filled.

[0055] The second tank, 2A-2D, with the lower pressure, is used first. When the equilibrium pressure between this second tank, 2A-2D, with the lower pressure, and the vehicle's tank is reached, filling continues from the second tank, 2A-2D, which has a pressure higher than this equilibrium pressure. Thus, the filling pressure is gradually increased, and the second tank, 2A-2D, with the higher hydrogen pressure, is used last.

[0056] After the distribution of gaseous hydrogen, the second tank 2A-2D with the lowest pressure will be used for a new refill of cold gaseous hydrogen from the first tank 1. Thus the second tanks 2A-2D are filled in turn, when they reach a pressure too low to be used for the distribution of gaseous hydrogen.

[0057] When a tank has a pressure too low for gas distribution but too high to be filled with cooled hydrogen gas from the first tank 1, the gas compressor 7 is used to lower the pressure of that tank and transfer the vapor to a higher-pressure tank. When the pressure becomes lower than that of the first tank 1 containing the cooled hydrogen gas, the transfer of said cooled hydrogen gas can be carried out as in the initial filling.

[0058] Thus, the 2A-2D tanks are filled in turn, when they reach a low pressure so that they can be used for the distribution of gaseous hydrogen.

Claims

1. A method for pressurising gaseous hydrogen comprising the following steps: ∘ providing a first tank (1) capable of receiving pressurised gaseous hydrogen; ∘ filling the first tank (1) with gaseous hydrogen compressed to a first pressure; ∘ cooling the compressed gaseous hydrogen inside or upstream of the first tank, such that the compressed gaseous hydrogen in the first tank (1) has a first cryogenic temperature; ∘ transferring by means of pressure equalisation a portion of the gaseous hydrogen at said first cryogenic temperature from said first tank (1) to at least one second tank (2); ∘ hermetically closing the at least one second tank containing the hydrogen transferred from the first tank; ∘ increasing the pressure in the second tank by heating the hydrogen present in the second tank to a second temperature higher than the first temperature.

2. The method according to claim 2, wherein the first tank is cooled by a cryogenic fluid such as liquid nitrogen or liquid methane or liquefied natural gas.

3. The method according to claim 1, wherein the gaseous hydrogen is cooled to the first temperature by a heat exchanger arranged upstream of the first tank.

4. The method according to claim 5, wherein the first tank comprises thermal insulation (9).

5. The method according to one of the preceding claims, wherein the maximum pressure in the first tank is comprised between 500 and 600 bar.

6. The method according to one of the preceding claims, wherein the maximum pressure in at the least one second tank is comprised between 1000 and 1500 bar.

7. The method according to one of the preceding claims, wherein the at least one second tank has a volume less than the volume of the first tank, for example the volume of the at least one second tank is comprised between 40% and 60% of the volume of the first tank.

8. The method according to one of the preceding claims, wherein the second temperature is comprised between -40°C and 25°C.

9. The method according to one of the preceding claims, comprising a heating step in the at least one second tank.

10. The method according to any one of claims 1 to 12, wherein a second tank is a tank of a vehicle.

11. A system for pressurising hydrogen comprising ∘ a first tank adapted to receive pressurised gaseous hydrogen; ∘ a cooling device capable of cooling the gaseous hydrogen inside or upstream of the first tank to a first cryogenic temperature, chosen from: ▪ a cryogenic fluid in which the first tank is immersed, ▪ conduits arranged in the first tank, said conduits being able to contain the cryogenic fluid so as to cool the first tank to the first temperature, and ▪ a heat exchanger arranged upstream of the first tank, ∘ a gas compressor adapted to compress gaseous hydrogen upstream of said first tank; ∘ a fluid connection adapted to selectively establish a fluid link between the first tank and a second tank so as to transfer pressurised gaseous hydrogen at the first cryogenic temperature from the first tank to the second tank by equalising the pressure, said second tank being able to be hermetically closed and to be at a second temperature higher than the first temperature of the first tank.

12. The system according to claim 11, wherein the cooling device comprises conduits arranged in the first tank, able to contain the cryogenic fluid, the system further comprising a thermal insulator arranged outside the conduits.

13. The system according to any one of claims 11 to 12, wherein a second tank comprises a heating device.

14. The system according to claim 13, wherein the heating device comprises conduits arranged for the circulation of a gas at a temperature greater than or equal to the second temperature.

15. The system according to claim 14, wherein the gas is nitrogen or helium.

16. The system according to any one of claims 13 to 15, wherein the at least one second tank also comprises a thermal insulation device.

17. A station for filling vehicles with gaseous hydrogen, comprising a system according to one of claims 13 to 16, the at least one second tank being a tank of a vehicle to be filled with gaseous hydrogen.