Method for cascade hydrogen distribution for a filling station for a hydrogen vehicle

Abstract

The invention relates to a method for cascade hydrogen distribution for a filling station for a hydrogen vehicle, the method comprising the following successive steps: a) filling a second hydrogen tank and a third hydrogen tank using a volume of hydrogen generated by a hydrogen generator positioned in the vicinity of the second tank or the third tank; the complete filling of the second hydrogen tank being carried out before starting to fill the third hydrogen tank; and - b) filling a tank of a hydrogen vehicle using the second hydrogen tank or the third hydrogen tank.

Description

Cascade hydrogen distribution method for a hydrogen vehicle refueling station Technical field of the invention

[0001] The present invention relates to a method for cascading hydrogen distribution for a hydrogen vehicle refueling station.

[0002] Hydrogen is a promising alternative fuel for vehicles due to its clean emissions and high efficiency. However, storing and transporting hydrogen can be challenging because of its low volumetric energy density.

[0003] Current techniques for filling hydrogen tanks for vehicles can be inefficient and time-consuming. Furthermore, the hydrogen compressors used for filling can be expensive and energy-intensive.

[0004] Hydrogen vehicle refueling is carried out from stations of 350 bar or 700 bar.

[0005] This filling pressure can be achieved either by a hydrogen compressor operating during vehicle refueling or by transferring hydrogen from the station's storage (upstream tank) to the vehicle's hydrogen tank (downstream tank). This transfer is achieved by equalizing the pressure between the station's storage and the vehicle's hydrogen tank.

[0006] The need is to improve the filling efficiency of the downstream tank while respecting the CEP (Clean Energy Partnership), namely primarily: - the number of openings / closings of the vehicle's tank filling valve must be less than or equal to 10; - the pressure during filling must not exceed 100% of the load permitted by the manufacturer (100%); - the final pressure in the vehicle's tank must not exceed 100% of the load permitted by the manufacturer (100%); - the pressure ramp must not be less than >1MPa / min (10bars / min).

[0007] One solution is to integrate into the filling chain an inline compressor regulated in flow and pressure allowing to fill to 100% of the authorized vehicle charge but has the disadvantage of adding an additional element, costly, bulky, requiring to be standardized to avoid explosions (risk of explosive atmosphere) and degrading the overall energy efficiency of the hydrogen filling station.

[0008] Filling with a compressor can heat the hydrogen, so it must be cooled and temperature regulated.

[0009] The hydrogen is pushed up to the permitted pressure and temperature limit of the tank.

[0010] The constraint of filling by spillage and pressure balancing is that filling is limited to pressure balancing between the two tanks.

[0011] Hydrogen is drawn from the downstream tank until pressure equalizes between the upstream and downstream tanks.

[0012] Upstream reservoir marked "1": P1=(n1RT1) / V1

[0013] Downstream reservoir marked "2": P2=(n2RT2) / V2

[0014] R = 8.3144621

[0015] T=T°K identical T1 and T2 by the equilibrium of temperatures.

[0016] Equilibrium pressure, denoted "Peq": Peq = ((n1 + n2) / (V1 + V2)) x RT

[0017] That is to say: the pressure in the downstream reservoir will never be at its maximum and the equilibrium pressure Peq will be reduced as the volume of the upstream reservoir is high.

[0018] There are cascade techniques that require changing cylinders. The principle, as illustrated, is to fill the RV reservoir from the cylinder with the lowest pressure of all the storage cylinders from R1 to Rn, and whose pressure is higher than the pressure in RV. Filling continues until the pressures between cylinder Rn and RV are equalized, using valves EV1 to EVNin and EV1out to EVNout (where N is the number of cylinders; in this example, there are four). Then the process starts again with the next cylinder, which has these two characteristics: the lowest pressure of all the storage cylinders from R1 to Rn, and a pressure higher than the pressure in RV.

[0019] The drawback is that once the bottles are empty, they are replaced with full ones, and the filling process can then begin again, which poses risks. It is also necessary to have a restricted-access unloading area during capacity exchanges.

[0020] The main drawback of this bottle replacement method is the logistical constraint, requiring the organization of a replacement schedule and anticipation of needs. Another drawback is the technical nature of the replacement process, which increases the risk of workplace accidents and leaks.

[0021] Some prior art documents show existing techniques for hydrogen distribution processes. One example is document AU2014273940, which describes a cascade hydrogen distribution process for a hydrogen vehicle refueling station.

[0022] We can also cite document EP3779263 showing a method for diagnosing faults in the pressure gauge of a hydrogen charging system, document EP3280946 describing a station and a method for filling a tank with a fuel gas, and document US3719196 showing a sequential container filling system.

[0023] None of the cited documents satisfy the objectives of the present invention. Presentation of the invention

[0024] The present invention aims to remedy these drawbacks with a completely innovative approach.

[0025] More specifically, the invention aims to protect a technical solution enabling an optimized and cooling-free hydrogen filling speed for hydrogen vehicles.

[0026] In particular, one objective of the invention is to provide such a technique as to make it possible to do away with any other complex adjustment system.

[0027] Another objective of the invention is to provide such a technique which is inexpensive to implement and does not require any special maintenance.

[0028] These objectives, as well as others that will appear subsequently, are achieved using a cascade hydrogen distribution process for a hydrogen vehicle refueling station, remarkable in that the process comprises the following successive steps: - a) filling a first hydrogen tank from a compressor in a preliminary step; - b) filling a second hydrogen tank and a third hydrogen tank from a volume of hydrogen generated by a hydrogen generator positioned near the second or third tank; the complete filling of the second hydrogen tank is carried out before the start of the filling of the third hydrogen tank; the volume of the first hydrogen tank is at least equal to the sum of the volumes of the second and third hydrogen tanks;- c) filling a hydrogen vehicle tank with said second hydrogen tank or with said third hydrogen tank; each filling has a filling pressure of at least 30 MPa / min.

[0029] According to one variant, the hydrogen generator fills a first tank which serves as a buffer tank and can through it supply the second or third hydrogen tank.

[0030] The process allows the second hydrogen tank to be filled first before proceeding to fill the third tank. This ensures that the second tank is fully filled before the third begins to be filled, thus guaranteeing efficient hydrogen distribution.

[0031] By fully filling the second tank before beginning to fill the third, the process minimizes the total time required to fully refuel both tanks. This can lead to reduced waiting times for hydrogen vehicle users, thus improving the overall experience.

[0032] The process offers the possibility of filling the first hydrogen tank from a hydrogen generator. This flexibility allows adaptation to different hydrogen supply configurations, which can be advantageous in situations where access to a hydrogen generator is more practical or cost-effective than filling from an already full tank (avoiding the risks associated with changing cylinders and reducing the risk of explosive atmospheres). There is no need for restricted areas around the filling station.

[0033] Producing hydrogen on-site avoids the costs associated with transporting it from a distant production site to the point of use. Transporting hydrogen in gaseous or liquid form can be expensive and involve significant losses. The concept of proximity refers to a distance of a few meters to a hundred meters. Reducing transport distances also decreases the carbon footprint associated with the process. Less fuel is used for transport, which helps reduce greenhouse gas emissions.

[0034] The specification of a minimum filling pressure of 30 MPa / min allows for rapid refueling of vehicles, meeting the requirements of modern hydrogen vehicles. This specification also reduces vehicle downtime.

[0035] The process according to the invention offers the advantage of significantly reducing the complexity of control and regulation systems by eliminating the need for conventional cascade filling architectures requiring multiple sensors, automated sequential valves, and associated controllers. Unlike prior art systems, the process does not rely on gradual balancing via tanks with differentiated pressures (such as a "storage bank") or on an oversized compressor operating in real time. This simplification allows for reduced maintenance, increased reliability, and more flexible integration in constrained environments, particularly for mobile stations or decentralized installations.Furthermore, the possible use of a hydrogen generator in the immediate vicinity of the tanks helps to limit heat losses and risks associated with the transport or handling of pressurized cylinders, thus providing a significant gain in safety and energy efficiency.

[0036] The invention is advantageously implemented according to the embodiments and variants set out below, which are to be considered individually or in any technically feasible combination.

[0037] In one embodiment, during step a), the hydrogen generator is either an electrochemical compressor or a mechanical compressor.

[0038] In one embodiment, during step a) or b), valves are configured to direct hydrogen to the first tank, the second tank, the third tank, or the tank of a hydrogen vehicle.

[0039] In one embodiment, during step a) or b), said valves include a control unit; said control unit includes a parameterization system configured to control said plurality of valves.

[0040] In one embodiment, during step a) or b), check valves are configured to block hydrogen back to the first tank, the second tank, the third tank, or the tank of a hydrogen vehicle.

[0041] In one embodiment, during step a) or b), the first tank, the second tank, the third tank and the tank of a hydrogen vehicle are made up of several sub-tanks corresponding to a part of a total volume of the first hydrogen volume, the second hydrogen volume, the third hydrogen volume and the tank of a hydrogen vehicle.

[0042] In one embodiment, during step b), the tank of a hydrogen vehicle being connected with an on-board system of a hydrogen vehicle comprising specific filling data of said vehicle comprising at least one of the following: an internal filling temperature in the fourth tank, a number of openings and closings of the valve bringing hydrogen into the tank of a hydrogen vehicle, a pressure, a pressure ramp rate, a filling rate of the tank of a hydrogen vehicle, an internal volume of the second and third tanks, a pressure transfer rate, an ambient temperature.

[0043] In one embodiment, during step b), the filling of the second tank is carried out before the filling of the third tank.

[0044] Thanks to these arrangements, filling only one tank at a time allows all available pressure to be concentrated on a single volume, which speeds up filling and reduces energy losses due to pressure drops or intermediate balances.

[0045] In one embodiment, during step b), said hydrogen generator is in a confined enclosure.

[0046] A containment enclosure is defined as a closed volume, sealed against hydrogen and ambient air, in which the hydrogen generator is integrated. This enclosure is designed to prevent the gas from dispersing into the external environment, even in the event of an internal leak, and to control the atmospheric conditions inside (pressure, ventilation, detection). In one variant, the containment enclosure is airtight.

[0047] In one embodiment, during step a) the compressor is positioned close to the first tank; this proximity is less than 10 meters.

[0048] Thanks to these arrangements, this proximity helps to limit pressure losses in the pipes, which also allows for better compression performance and a reduction in energy consumption.

[0049] Another significant advantage of the process according to the invention lies in the reduction of constraints related to ATEX zones (explosive atmospheres). Indeed, by using a hydrogen generator located in the immediate vicinity of the storage tanks (intermediate or buffer tanks), the invention makes it possible to avoid or limit the ATEX-classified zones to the generator's confined enclosure alone, without needing to extend this classification to the entire station. This configuration reduces regulatory requirements, development costs, and site safety obligations. The proximity of the functional components (generator, tanks, filling circuit) also minimizes piping lengths, pressure losses, and the risk of leaks, while simplifying supervision and maintenance.This localized positioning of critical components thus helps to improve the overall safety of the station, while optimizing its compactness and ease of installation in sensitive or urban environments. Brief description of the figures

[0050] Other advantages, purposes and features of the present invention will become apparent from the following description, given for explanatory purposes and in no way as a limitation, with reference to the accompanying drawings, in which:

[0051] This represents (the state of the art) a diagram of the operation of cascaded distribution;

[0052] This represents a diagram of the operation of the cascade hydrogen distribution system for hydrogen vehicles;

[0053] Lare represents a flowchart of the operation of the cascade hydrogen distribution process for hydrogen vehicles.

[0054] Laa has been described above.

[0055] Lamontre a diagram of the operation of the cascade hydrogen distribution system for hydrogen vehicles.

[0056] The upper part shows a first tank and a compressor which is directed towards the second tank R2 or the third tank R3. The direction of the opening or closing of the filling is controlled by valves (EV3in or EV2in).

[0057] The EV1 valve allows the first tank to be filled from the compressor.

[0058] The EV4 valve allows the tank of a hydrogen vehicle to be filled from the second tank R2 or the third tank R3.

[0059] To fill a hydrogen vehicle tank, designated R4, the filling system consists of two storage tanks called:

[0060] Third tank R3: large capacity tank with volume V3, pressure P3 and number of moles n3

[0061] Second tank R2: small capacity tank with volume V2, pressure P2, and number of moles n2, where:

[0062] V2 < V3 and P2 >= P3

[0063] The filling system prioritizes the complete filling of the second tank before filling the third tank.

[0064] R4: hydrogen vehicle tank

[0065] The two tanks are filled either by a compressor or by a set of tanks upstream of R3 and R2.

[0066] The upstream reservoir is called R1 with volume V1, pressure P1 and number of moles n1:

[0067] V1 > V2+V3 and P1 > P2 >= P3 and n1> n2 + n3

[0068] According to one variant, the R1, R2, R3 and R4 tanks are each composed of one or more tanks.

[0069] Case #1: Filling by a compressor

[0070] The filling process is done by pushing the hydrogen through.

[0071] R2 filling: R2 filling takes priority to reach full capacity.

[0072] R3 filling:

[0073] When R2 = 100% of its capacity, the compressor fills R3 to full R3 charge.

[0074] This allows us to immediately start filling a hydrogen vehicle's tank without waiting for R3 to be fully charged.

[0075] Case #2: Filling via an upstream reservoir R1

[0076] The filling process is done by pouring in hydrogen using the principle of pressure balancing.

[0077] R2 filling: R2 filling takes priority to reach full capacity.

[0078] Filling R3: When R2 = 100% of its capacity, the tank R1 pours hydrogen into R3 until pressure equilibrium P1 = P3 or until R3 is fully charged.

[0079] This allows us to immediately start filling a hydrogen vehicle's tank without waiting for R3 to be fully charged.

[0080] The black arrows indicate that there is control information for the valves depending on the desired configuration.

[0081] Check valves are also shown.

[0082] According to one example of implementation, hydrogen is generated by an electrochemical compressor or a mechanical compressor.

[0083] An electrochemical compressor is a type of hydrogen compressor that uses an electrochemical reaction to compress hydrogen gas. This type of compressor is oil-free and has no moving parts, making it more compact, reliable, and environmentally friendly than traditional piston or centrifugal compressors.

[0084] The compressor generates hydrogen with a predefined pressure, number of moles, and volume.

[0085] All the hydrogen volumes generated by the compressor are produced under high pressure.

[0086] High pressure is equivalent to a pressure between 25 MPa and 60 MPa, preferably 30 MPa.

[0087] To ensure operational safety while reducing regulatory constraints, the hydrogen generator is integrated into a sealed, confined enclosure equipped with programmable threshold hydrogen detection sensors.

[0088] In one variant, there is also a controlled ventilation system, as well as a relative depression maintained by forced extraction.

[0089] The hydrogen generator enclosure is designed to prevent any accumulation of hydrogen in the immediate environment and to avoid the formation of an explosive atmosphere, in accordance with applicable standards (IEC 60079-10-1). Furthermore, the entire system is connected to the filling circuit via hermetic interfaces, preventing any leakage to the outside. Thanks to this contained architecture, the generator operates in a non-ATEX zone or, at a minimum, in a small, controlled ATEX zone, generally classified as Zone 2, which does not extend to the entire station. This containment allows the generator to be installed in close proximity to the intermediate tanks, while minimizing risks, safety distances, and the need for ATEX equipment for surrounding components.

[0090] This hydrogen distribution is regulated according to an ATEX zone, an acronym for explosive atmosphere.

[0091] An ATEX zone is an area where there is a risk of explosion due to the presence of flammable substances in the form of gases, vapors, mists or dusts suspended in the air.

[0092] According to this distribution method, the ATEX zone is located on the storage and distribution of hydrogen.

[0093] The non-ATEX zone corresponds to the hydrogen production area.

[0094] As an example, the ATEX zone and the non-ATEX zone have a proximity of less than 10 meters.

[0095] This proximity helps to limit pressure losses in the pipes, which also allows for better compression performance and reduced energy consumption.

[0096] Naturally, the invention described above is by way of example. It is understood that a person skilled in the art is capable of carrying out different embodiments of the invention without departing from its scope.

[0097] Lamontre a flowchart of the operation of the cascade hydrogen distribution process for hydrogen vehicles.

[0098] When the hydrogen vehicle, represented by the R4 tank, is connected to the refueling station via the filling nozzle incorporating an EV4 solenoid valve, the following information (non-exhaustive) is measured and / or read either from the vehicle's on-board system or from a database integrated into the refueling station, allowing the selection of the hydrogen vehicle model to be refueled and the determination of the vehicle's specific refueling parameters:

[0099] Settings:

[0100] T_max_R4: maximum internal filling temperature in R4

[0101] T_min_R4: Minimum internal filling temperature in R4

[0102] n_max_R4: maximum number of opening / closing cycles of the R4 tank inlet valve

[0103] p_max_R4: maximum internal pressure of R4

[0104] p_rate_min_R4: minimum pressure ramp rate in R4

[0105] p_rate_max_R4: maximum pressure ramp rate in R4

[0106] Q_max_R4: maximum filling flow rate in R4

[0107] V_tank_R2: internal volume of R2

[0108] V_tank_R3: internal volume of R3

[0109] p_rate_low: low pressure ramp rate

[0110] p_rate_hi: high rate of pressure ramp

[0111] …

[0112] Measures :

[0113] p_vehicle_R4: internal pressure measured in R4

[0114] T_vehicle_R4: internal temperature measured in R4

[0115] p_rate_R4: measured pressure transfer velocity in R4

[0116] p_tank_R2: internal pressure measured in R2

[0117] T_tank_R2: internal temperature measured in R2

[0118] p_tank_R3: internal pressure measured in R3

[0119] T_tank_R3: internal temperature measured in R3

[0120] T_amb: measured ambient temperature

[0121] Q_R4: Filling flow rate measured in R4

[0122] …

[0123] Controls:

[0124] Casc_on: command of the cascade function

[0125] S_EV2in: control of the EV2in valve

[0126] S_EV2out: EV2out valve control

[0127] S_EV3in: EV3in valve control

[0128] S_EV3out: EV3out valve control

[0129] S_EV4: EV4 valve control

[0130] …

[0131] Lamontre shows one of the possible sequences for filling from all the required values. This helps explain the system's operation, particularly with the use of non-proportional solenoid valves to meet CEP requirements.

[0132] Part of the diagram can be explained as follows: if the tank valve R3 is open and the tank valve R2 is closed, then the cascade function is activated.

[0133] The filling of the R4 vehicle's hydrogen tank is activated by the gun valve as long as the measured pressure transfer velocity in R4 is greater than the predetermined low pressure transfer velocity rate (p_rate_low).

[0134] If the measured pressure transfer velocity in R4 is less than a low threshold (p_rate_low) then the tank valve R3 is closed and the tank valve R2 is open.

[0135] If the measured pressure transfer velocity in R4 is greater than the predetermined high rate of pressure transfer velocity (p_rate_hi) or if the pressure in tank R2 is less than the pressure in tank R3, then the tank valve R3 is open and the tank valve R2 is closed.

[0136] It is emphasized that all features, as they are apparent to a person skilled in the art from this description, drawings and attached features, even if in practice they have only been described in relation to other specific features, both individually and in any combinations, may be combined with other features or groups of features disclosed herein, provided that this has not been expressly excluded or that technical circumstances render such combinations impossible or meaningless.

Claims

A cascade hydrogen distribution method for a hydrogen vehicle refueling station, characterized in that the method comprises the following successive steps: - a) filling a first hydrogen tank from a compressor in a preliminary step; - b) filling a second hydrogen tank and a third hydrogen tank from a volume of hydrogen generated by a hydrogen generator positioned near the second or third tank; the second hydrogen tank is fully filled before the third hydrogen tank is filled; the volume of the first hydrogen tank is at least equal to the sum of the volumes of the second and third hydrogen tanks; - c) filling a hydrogen vehicle tank with said second or third hydrogen tank;each filling involves a filling pressure of at least 30 MPa / min. A method according to claim 1, wherein in step a), the hydrogen generator is either an electrochemical compressor or a mechanical compressor. A method according to claim 1, wherein in step a) or b), valves are configured to direct hydrogen to the first tank, the second tank, the third tank, or the tank of a hydrogen vehicle. A method according to claim 3, wherein in step a) or b), said valves comprise a control unit; said control unit comprises a parameterization system configured to control said plurality of valves. A method according to claim 1, wherein in step a) or b), check valves are configured to block hydrogen back to the first tank, the second tank, the third tank, or the tank of a hydrogen vehicle. A method according to claim 1, wherein in step a) or b), the first tank, the second tank, the third tank and the tank of a hydrogen vehicle are made up of several sub-tanks corresponding to a part of a total volume of the first hydrogen volume, the second hydrogen volume, the third hydrogen volume and the tank of a hydrogen vehicle. A method according to claim 1, wherein in step b), the tank of a hydrogen vehicle is connected with an on-board system of a hydrogen vehicle comprising specific filling data of said vehicle comprising at least one of the following: an internal filling temperature in the fourth tank, a number of openings and closings of the valve bringing hydrogen into the tank of a hydrogen vehicle, a pressure, a pressure ramp rate, a filling flow rate of the tank of a hydrogen vehicle, an internal volume of the second and third tanks, a pressure transfer rate, an ambient temperature. A method according to claim 1, wherein in step b), the filling of the second tank is carried out before the filling of the third tank. A method according to claim 1, wherein in step b), said hydrogen generator is in a confined enclosure. A method according to claim 9, wherein in step a) the compressor is positioned close to the first tank; this proximity is less than 10 meters.

Images