Cascade hydrogen distribution method for a hydrogen vehicle refueling station

Abstract

The invention relates to a cascade hydrogen distribution method for a hydrogen vehicle refueling station, characterized in that the method comprises the following successive steps: a) 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 completely filled before the third hydrogen tank is filled; b) filling a hydrogen vehicle tank with said second or third hydrogen tank. Figure for the abstract: Fig. 2

Description

Title of the invention: Method for cascading hydrogen distribution for a hydrogen vehicle refueling station Technical field of the invention

[0001] The present invention relates to a method of cascading hydrogen distribution for a hydrogen vehicle filling station. Previous technique

[0002] Hydrogen is a promising alternative fuel for vehicles due to its clean emissions and high efficiency. However, the storage and transport of hydrogen can be difficult due to its low volumetric energy density.

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

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

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

[0006] The need is to improve the filling efficiency of the downstream tank while respecting the CEP (Clean Energy Partnership), namely mainly: - number of opening / closings of the vehicle's tank filler valve less than or equal to 10; - the pressure during filling must not exceed 100% of the load allowed 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 (1Obars / 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 having 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 by 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 the filling is limited to pressure balancing between the two tanks.

[0011] Hydrogen is drawn through the downstream reservoir until pressure is equalized between the upstream and downstream reservoirs.

[0012] Upstream Reservoir marked "1": Pl=(nlRTl) / Vl

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

[0014] R= 8.3144621

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

[0016] Equilibrium pressure denoted “Peq”: Peq=((nl+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, illustrated in [Fig. 1], is to fill the RV reservoir from the cylinder with the lowest pressure of all the RI storage cylinders at 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 EVlout to EVNout (N being the number of cylinders; in this example, there are 4). Then the process starts again with the next cylinder having these two characteristics: the lowest pressure of all the RI storage cylinders at 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, leading to 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. The other drawback is the technical nature of the replacement process, increasing the risk of workplace accidents and leaks. Presentation of the invention

[0021] The present invention aims to remedy these drawbacks with a totally innovative approach.

[0022] More specifically, the invention aims to protect a technical solution enabling an optimized and uncooled hydrogen filling speed for hydrogen vehicles.

[0023] In particular, an objective of the invention is to provide such a technique making it possible to do away with any other complex adjustment system.

[0024] Another objective of the invention is to provide such a technique which is inexpensive to implement and which does not require any special maintenance.

[0025] These objectives, as well as others that will appear subsequently, are achieved using a cascade hydrogen distribution process for a hydrogen vehicle refueling station, notable in that the process comprises the following successive steps: - a) fill 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; - b) fill a hydrogen vehicle tank with said second hydrogen tank or with said third hydrogen tank.

[0026] According to one variant, the hydrogen generator fills a first tank which serves as a buffer tank and can through it supply the second hydrogen tank or the third hydrogen tank.

[0027] 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 completely filled before the third tank begins to be filled, thus ensuring efficient hydrogen distribution.

[0028] By filling the second tank completely before starting to fill the third tank, the process minimizes the total time required to fully fill the tanks. This can lead to reduced waiting times for hydrogen vehicle users, thus improving the overall experience.

[0029] The method 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, reduced risk of explosive atmosphere). There is no need for restricted areas around the filling station.

[0030] Producing hydrogen on-site avoids the costs associated with transporting hydrogen 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. By reducing transport distances, there is also a reduction in the carbon footprint associated with the process. Less fuel is used for transport, which helps to reduce greenhouse gas emissions.

[0031] The invention is advantageously implemented according to the embodiments and variants set out below, which are to be considered individually or according to any technically operative combination.

[0032] In one embodiment, during step a), the hydrogen generator is either an electrochemical compressor or a mechanical compressor.

[0033] In one embodiment, during step a), the hydrogen generator fills a first tank and the volume of the first hydrogen tank is at least equal to the sum of the volumes of the second and third hydrogen tanks.

[0034] In one embodiment, there is a step prior to step a) of filling the first tank by a compressor.

[0035] In one embodiment, during the hydrogen filling steps the filling pressure is at least equal to IMPa / min.

[0036] 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.

[0037] 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.

[0038] 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.

[0039] 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.

[0040] 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 elements: 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. Brief description of the figures

[0041] 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:

[0042] Fig. 1 represents (state of the art) a diagram of the operation of cascade distribution;

[0043] Fig. 2 represents a diagram of the operation of the cascade hydrogen distribution for a hydrogen vehicle;

[0044] Fig. 3 represents a flowchart of the operation of the cascade hydrogen distribution process for hydrogen vehicles. Description of the implementation methods

[0045] The [Fig.1] has been described above.

[0046] Fig. 2 shows a diagram of the operation of the cascade hydrogen distribution for a hydrogen vehicle.

[0047] The upper part shows a first tank and a compressor which is oriented towards the second tank R2 or the third tank R3. The orientation of the opening or closing of the filling is controlled by valves (EV3in or EV2in).

[0048] The EV1 valve allows the first tank to be filled from the compressor.

[0049] The EV4 valve allows the tank of a hydrogen vehicle to be filled from the second tank R2 or third tank R3.

[0050] To fill a hydrogen vehicle tank, denoted R4, the filling system consists of two storage tanks called:

[0051] Third tank R3: large capacity tank with volume V3, pressure P3 and number of moles n3

[0052] Second tank R2: small capacity tank with volume V2 and pressure P2 and number of moles n2 with:

[0053] V2 < V3 and P2>=P3

[0054] R4: hydrogen vehicle tank

[0055] The two tanks are filled either by a compressor or by a set of tanks upstream of R3 and R2.

[0056] The upstream reservoir is called RI, with volume VI, pressure PI, and number of moles ni:

[0057] VI > V2 + V3 and PI > P2 >= P3 and nl > n2 + n3

[0058] According to one variant, the RI, R2, R3 and R4 tanks are each composed of one or more tanks.

[0059] Case no. 1: filling by a compressor

[0060] Filling is done by pushing the hydrogen.

[0061] Filling R2: Filling R2 has priority to reach full capacity.

[0062] Filling R3:

[0063] When R2 = 100% of its capacity, the compressor fills R3 up to the full charge of R3.

[0064] This makes it possible to immediately start filling a hydrogen vehicle tank without waiting for R3 to be fully charged.

[0065] Case No. 2: Filling from an upstream RI reservoir

[0066] Filling is done by pouring in hydrogen using the principle of pressure balancing.

[0067] Filling R2: Filling R2 has priority to reach full capacity.

[0068] Filling R3: When R2 = 100% of its capacity, the RI reservoir pours hydrogen into R3 until pressure equilibrium PI = P3 or until R3 is fully charged.

[0069] This makes it possible to immediately start filling a hydrogen vehicle tank without waiting for R3 to be fully charged.

[0070] The black arrows indicate that there is control information for the valves according to the desired configuration.

[0071] Check valves are also shown.

[0072] According to one embodiment, hydrogen is generated by an electrochemical compressor or a mechanical compressor.

[0073] 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, more reliable, and more environmentally friendly than traditional piston or centrifugal compressors.

[0074] The compressor generates hydrogen with a predefined pressure, number of moles, and volume.

[0075] Naturally, the invention is described above by way of example. It is understood that a person skilled in the art is able to carry out different embodiments of the invention without departing from the scope of the invention.

[0076] Fig. 3 shows a flowchart of the operation of the cascade hydrogen distribution process for hydrogen vehicles.

[0077] 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, which is not exhaustive, is measured and / or read either in the vehicle's on-board system or in 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:

[0078] Parameters:

[0079] T_max_R4: maximum internal filling temperature in R4

[0080] T_min_R4: minimum internal filling temperature in R4

[0081] n_max_R4: maximum number of opening / closing operations of the R4 tank inlet valve

[0082] p_max_R4: maximum internal pressure of R4

[0083] p_rate_min_R4: minimum pressure ramp rate in R4

[0084] p_rate_max_R4: maximum pressure ramp rate in R4

[0085] Q_max_R4: maximum filling flow rate in R4

[0086] V_tank_R2: internal volume of R2

[0087] V_tank_R3: internal volume of R3

[0088] p_rate_low: low pressure ramp rate

[0089] p_rate_hi: high rate of pressure ramp

[0090]

[0091] Measures:

[0092] p_vehicle_R4: internal pressure measured in R4

[0093] T_vehicle_R4: internal temperature measured in R4

[0094] p_rate_R4: measured velocity of pressure transfer in R4

[0095] p_tank_R2: internal pressure measured in R2

[0096] T_tank_R2: internal temperature measured in R2

[0097] p_tank_R3: internal pressure measured in R3

[0098] T_tank_R3: internal temperature measured in R3

[0099] T_amb: measured ambient temperature

[0100] Q_R4: filling flow rate measured in R4

[0101]

[0102] Controls:

[0103] Casc_on: command of the cascade function

[0104] S_EV2in: control of the EV2in valve

[0105] S_EV2out: EV2out valve control

[0106] S_EV3in: EV3in valve control

[0107] S_EV3out: EV3out valve control

[0108] S_EV4: EV4 valve control

[0109]

[0110] Figure 3 shows one of the possible sequences of a filling from all the required values. This helps to explain the operation of the system, in particular with the use of non-proportional solenoid valves to meet CEP requirements.

[0111] 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.

[0112] The filling of the hydrogen tank of vehicle R4 is activated by the gun valve as long as the measured velocity of pressure transfer in R4 is greater than the predetermined low rate of pressure transfer velocity (p_rate_low).

[0113] 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.

[0114] If the measured pressure transfer velocity in R4 is greater than the high predetermined pressure transfer velocity rate (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.

[0115] It is emphasized that all features, as they are apparent to a person skilled in the art from the present 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, can be combined with other features or groups of features disclosed herein, provided that this has not been expressly excluded or that technical circumstances make such combinations impossible or meaningless.

Claims

Demands

1. A cascade hydrogen distribution method for a hydrogen vehicle refueling station, characterized in that the method comprises the following successive steps: - a) 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; - b) filling a hydrogen vehicle tank with said second or third hydrogen tank.

2. A method according to claim 1, wherein in step a), the hydrogen generator is either an electrochemical compressor or a mechanical compressor.

3. A method according to claim 1, wherein in step a), the hydrogen generator fills a first tank and the volume of the first hydrogen tank is at least equal to the sum of the volumes of the second and third hydrogen tanks.

4. Method according to claim 3, wherein there is a step prior to step a) of filling the first tank by a compressor.

5. A method according to claim 1, wherein during the hydrogen filling steps the filling pressure is at least equal to IMPa / min.

6. A method according to claim 3, 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.

7. A method according to claim 6, 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.

8. A method according to claim 3, wherein in step a) or b), check valves are configured to block hydrogen to the first tank, the second tank, the third tank, or the tank of a hydrogen vehicle.

9. A method according to claim 3, 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.

10. A method according to claim 1, wherein in 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.

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