Diffuser, reservoir and rinsing process

Abstract

Diffuser, Reservoir, and Flushing Method. The invention relates to a diffuser (10) for a reservoir (1) for pressurized gases, such as hydrogen, wherein the diffuser (10) is internal to the reservoir (1) and shaped to inject a pressurized gas. The invention further relates to a reservoir (1) comprising such a diffuser (10). The invention also relates to a flushing method for such a reservoir (1). Abstract Figure: Figure 1. Figure for the abstract: Figure 1.

Description

Title of the invention: Diffuser, reservoir and rinsing method

[0001] The invention relates to a diffuser for a reservoir of pressurized gas, such as hydrogen, where the diffuser is internal to the reservoir and shaped to inject a pressurized gas.

[0002] Flushing a gas tank is the operation which allows the replacement of an old gas with a new gas, until a concentration of new gas in the tank is obtained, which is greater than a given threshold.

[0003] It is known that a dilution process can be used to flush a tank initially containing an old gas. In such a process, the tank is first filled with new gas under pressure. The tank then contains a mixture of the new and old gases. In a second step, the gas mixture from the tank is drawn off. The flushing continues by repeating a cycle comprising these two steps. With each repetition, the mixture becomes increasingly rich in new gas and increasingly less rich in old gas. The process is stopped as soon as the concentration of new gas is deemed acceptable, i.e., above a given threshold.

[0004] An advantage of such a process is that it can be carried out by means of a single fluidic device, usable both for filling and for drawing and therefore generally pre-existing on any tank, such a fluidic device being necessary for its nominal use.

[0005] A major drawback of such a process is that it requires a large number of dilution cycles, resulting in a prohibitive rinsing time.

[0006] Therefore, an alternative to the dilution process is being sought.

[0007] The invention proposes to implement a method for flushing a tank by sweeping. A sweeping flushing method is based on injecting the new gas through a fluidic device and simultaneously recovering the gas mixture through another fluidic device. Such a method requires a tank adapted for sweeping. To facilitate sweeping, a diffuser is used.

[0008] The invention relates to a diffuser for a reservoir for pressurized gas, such as hydrogen, where said diffuser is internal to the reservoir and shaped to inject a pressurized gas.

[0009] Specific features or embodiments, usable alone or in combination, are:

[0010] - the diffuser is extended by at least one cannula forming an angle with the diffuser less than 90°,

[0011] - said at least one cannula comprises at least two cannulas angularly evenly distributed around the diffuser,

[0012] - said at least two cannulas are not coplanar with the diffuser in such a way to make the injected gas swirl,

[0013] - said at least one cannula is circular at 360° around the diffuser,

[0014] - said at least one cannula is rotatable around the diffuser.

[0015] The invention further relates to a reservoir, for pressurized gas, such as hydrogen, comprising such a diffuser.

[0016] Specific features or embodiments, usable alone or in combination, are:

[0017] - the reservoir includes a first fluidic device, comprising at least one a first valve suitable for drawing from the reservoir and a second fluidic device comprising at least a second valve suitable for filling the reservoir, where the second fluidic device includes the diffuser,

[0018] - the first fluidic device is disposed at a first end of the reservoir and the second device is positioned at a second end of the tank opposite the first end.

[0019] The invention further relates to a method of rinsing a tank by sweeping, using rinsing equipment, comprising the following steps:

[0020] - connection of an outlet of the rinsing tool to the second valve, and connection from an inlet of the rinsing equipment to the first valve, simultaneously or in any order,

[0021] - opening of the first valve, and possible opening of the second valve, simultaneously or in any order,

[0022] - sending the new pressurized gas via the outlet of the rinsing tool and recovery of the outgoing gas via the inlet of the rinsing equipment, for a predetermined rinsing duration,

[0023] - closing of the first valve,

[0024] - stopping the gas supply when the desired gas pressure is reached in the reservoir,

[0025] - possible closure of the second valve.

[0026] The invention will be better understood upon reading the following description, given solely by way of example, and with reference to the figures in the appendix in which:

[0027] [Fig. 1] shows, in axial sectional view, a reservoir according to a first embodiment,

[0028] [Fig.2] shows, in axial sectional view, a reservoir according to a second embodiment,

[0029] [Fig.3] shows, in axial sectional view, one end of a tank,

[0030] [Fig.4] shows, in front view, the end of the [Fig.3],

[0031] [Fig.5] illustrates the principle of rinsing by sweeping,

[0032] [Fig.6] shows, in a cut longitudinal view, a first embodiment of the diffuser,

[0033] [Fig.7] shows, in perspective view, the diffuser of the [Fig.6],

[0034] [Fig.8] shows, in longitudinal cutaway view, the diffuser of the [Fig.6],

[0035] [Fig.9] shows, in longitudinal view, another embodiment of the diffuser,

[0036] [Fig. 10] shows, in cut transverse view, a detail of the diffuser of [Fig.9],

[0037] [Fig. 11] shows, in perspective view, another embodiment of the diffuser,

[0038] [Fig.12] shows, in longitudinal view, the diffuser of the [Fig.11].

[0039] With reference to [Fig. 1 or 2], the invention relates to a reservoir 1, for gas under pressure, such as hydrogen. This tank 1 includes a first fluidic device 2. For the purposes of the rinsing process, this first fluidic device 2 includes at least one first valve 4, suitable for drawing from tank 1. This first fluidic device 2 may have other functions. Advantageously, this first fluidic device 2 is the fluidic device 2, known from the prior art, which is used throughout the life cycle of a tank 1. It is also called an OTV (from the English "On Tank Valve"). Such a fluidic device 2 is suitable for drawing from, but also for filling, tank 1. It also provides monitoring and safety functions, such as pressure and / or temperature monitoring, or gas release in the event of critical overpressure.

[0040] According to a feature specific to an adaptation for a flushing process, the tank 1 further comprises a second fluidic device 3. This second fluidic device 3 may be called EP, from the English "End Plug". This second fluidic device 3 includes at least one second valve 5, suitable for use in filling.

[0041] As illustrated in [Fig. 3], according to another feature, the second fluidic device 3 further comprises a diffuser 10. This diffuser 10 is internal to the reservoir 1 and is directed towards the interior of the reservoir 1, substantially along the axis A, connecting the first fluidic device 2 to the second fluidic device 3. It allows the second fluidic device 3 to be connected to the interior of the reservoir 1. This diffuser 10 is shaped to inject a pressurized gas into the reservoir 1.

[0042] As illustrated in Figures 3 and 4, according to another advantageous feature, the diffuser 10 is extended inwards by at least one cannula 11. This at least one cannula 11 advantageously forms an angle α of less than 90° with the diffuser 10, and therefore with axis A. Furthermore, this cannula 11 allows the new gas, introduced by the second valve 5, to be "blown" towards the counter-current zones, stop zones, or dead zones at the bottom of tank 1 which, otherwise, might remain out of range of the sweeping.

[0043] Adjusting the length of the pressurized gas jet is easily achieved by modulating the cumulative passage area of ​​the cannula(s) 11 relative to the passage area of ​​the diffuser 10.

[0044] According to another advantageous feature, said at least one cannula 11 comprises at least two cannulas 11 and preferably three or four cannulas 11. These cannulas 11 are advantageously angularly equidistant around the diffuser 10. Thus, [Fig. 4] illustrates an example with three cannulas 11, arranged at 3° intervals (3 = 120°). The increased number of cannulas 11 advantageously improves the scanning effect of dead zones. The equidistant distribution of the cannulas 11 contributes to homogenizing the scanning.

[0045] This acute angle characteristic is illustrated by the embodiment of a diffuser 10 shown in Figures 6-8. This diffuser 10 is made of stamped sheet metal. It may be metal sheet, such as a light alloy. Alternatively, such a diffuser 10 may be made of plastic, typically by injection molding. This diffuser 10 comprises a predominantly cylindrical body, suitable for press-fitting onto the end of a pipe of the second device 3. At its other end, the diffuser 10 includes a cap 16 having a cavity 14 that helps to direct the diffused gas jets. The sides of the diffuser 10 are pierced with openings 13. These openings 13 form the nozzles 11. The shape of the openings 13 allows the gas jets to be directed at an acute angle α. This embodiment allows for a simple and inexpensive fabrication of the diffuser.

[0046] According to another feature, said at least two cannulas 11 are not coplanar with the diffuser 10. This angular offset, advantageously identical for all cannulas 11, advantageously creates a tangential component which causes the injected gas to swirl. Such a swirl improves the flushing of the reservoir 1.

[0047] This vortex characteristic is illustrated by the embodiment of a diffuser 10 shown in figures 9 and 10. In this embodiment the diffuser 10 comprises, before a terminal cap 16, a stage assembling fins 15.

[0048] These fins 15 form cannulas 11 together. The helical shape of these cannulas 11 produces a vortex effect which drives the gas jets.

[0049] It is obviously possible to combine the two preceding characteristics, acute angle and vortex. This is illustrated by the embodiment of a diffuser 10 shown in Figures 11 and 12. In this diffuser 10, channels 16 are hollowed out. These channels 16 form the cannulas 11. They have an acute angle relative to the axis. They also have a helical shape, so as not to be coplanar with diffuser 10. Thus, they induce a swirling effect applied to the gas jets, while directing said gas jets towards the dead zones of tank 1.

[0050] According to another feature (not illustrated), generalizing the cannula multiplication feature 11, the number of cannulas 11 is increased to infinity, creating a single circular cannula 11 with 360° of revolution around the diffuser 10. This advantageously makes it possible to obtain a conical jet, increasing the areas swept by the pressurized gas.

[0051] According to another feature (not shown), at least one cannula 11 is rotatable about the diffuser 10. Such rotation can be achieved, both for discrete cannulas 11 and for a single circular cannula, by a rotational degree of freedom, obtained by any known means, complemented by the preceding non-coplanarity feature. Thus, the cannula(s) 11 are free to rotate about the diffuser 10, and the passage of pressurized gas through the cannula(s) 11 produces the rotation.

[0052] According to another feature, the second valve 5 is a check valve 6. This check valve 6 is oriented so as to be open in the direction from the outside to the inside of the tank 1 and to be closed in the opposite direction. This preferred embodiment advantageously allows the rinsing process to be automated, the opening of the second valve 5 being achieved by the application of a rinsing pressure in the direction from the outside to the inside of the tank 1, without manual intervention.

[0053] According to another feature, the second valve 5 is a simple valve 7, preferably manually operated. Such a simple manual valve 7 is advantageously less expensive than the check valve 6 of the previous embodiment. However, this embodiment is a degraded embodiment compared to the previous one in that it requires manual operation of the simple valve 7 to open it during flushing pressurization.

[0054] According to another feature, the second valve 5 comprises a non-return valve 6 and a simple valve 7, preferably manual, mounted in series. This ensures redundancy of external sealing. Although more expensive than the previously described embodiments, this embodiment improves the safety of the tank 1.

[0055] According to another feature, the first fluidic device 2 is disposed at a first end 8 of the tank 1 and the second fluidic device 3 is disposed at a second end 9 of the tank 1, opposite the first end 8.

[0056] Advantageously, for a reservoir 1 having a longitudinal extension along an axis A, the two fluidic devices 2, 3 are preferably arranged at the respective ends of this extension. Thus, a front 12 between the old gas "fluid A" and the new gas "fluid B" presents the smallest possible surface area, namely the cross-section of the tank 1 perpendicular to the axis of the extension. As illustrated in [Fig. 5], this optimizes the flushing of the old gas "fluid A" by the new gas "fluid B" during rinsing, thereby facilitating and / or accelerating the rinsing process.

[0057] The invention further relates to a method for flushing such a tank 1 by sweeping. This method uses a flushing tool. The flushing tool typically comprises a first pipe including an outlet connector adapted to be hermetically sealed to the second valve 5 and adapted to be supplied by a fresh gas supply means, including, for example, a fresh gas tank and a pump. The flushing tool further comprises a second pipe including an inlet connector adapted to be hermetically sealed to the first valve 4, in order to allow the outlet and optionally the recovery of the gas mixture exiting the tank 1. In its simplest version, the second pipe includes a venting cannula. Alternatively, it includes a storage means, such as a tank, adapted to store the exiting mixture.

[0058] The rinsing process comprises the following steps. The rinsing tool is placed on the tank 1 to be rinsed. For this purpose, in a first step, its outlet is connected to the second valve 5, and in a second step, which may be prior, simultaneous, or subsequent, its inlet is connected to the first valve 4.

[0059] In a third step, the first valve 4 is opened. If this first valve 4 is a tapping valve for the OTV, it may be a solenoid valve that can be electrically controlled by a control device, possibly grouped with or integrated into the control of the rinsing equipment. Alternatively, it may also be a manual valve, operated manually or by means of a tool. This first open valve 4 allows the gas mixture to be drawn off / drained from the tank 1.

[0060] In a subsequent fourth step, the second valve 5 may be opened. This opening is optional because, according to the embodiment, it is not necessary. In the case of a simple valve 7, this valve must be opened. However, in the case of a check valve 6, the opening is automatically triggered by the introduction of new gas in the following step.

[0061] The third and fourth steps can be carried out, in that order, simultaneously or in reverse order.

[0062] In a subsequent fifth step, the new pressurized gas is sent via the outlet of the rinsing tooling. This introduces, via the second valve 5, new gas into the tank 1.

[0063] This results in the gas, a mixture of new and old gas, exiting via the first valve 4. This gas mixture is possibly recovered via the inlet of the rinsing tooling.

[0064] This step of introducing the new gas, which effectively performs the flushing by sweeping, is maintained for a predetermined flushing time. This flushing time is determined so as to achieve a desired final concentration of new gas (or, equivalently, a residual concentration of old gas).

[0065] This determination can be pre-carried out by tests or by numerical simulation.

[0066] Alternatively, to a maintenance for a predetermined duration, the maintenance of the sending of new gas can be controlled by a measurement of the effective concentration, compared to an objective concentration.

[0067] Once the target, elapsed time and concentration deemed to have been reached or concentration actually reached, during a sixth step, the first valve 4 is closed.

[0068] The supply of fresh gas is advantageously maintained until a desired gas pressure is reached in tank 1. Here again, this pressure can be considered to have been reached after a predetermined time, or actually reached by a control system based on an actual pressure measurement. This step ends with the cessation of the supply of fresh gas.

[0069] A possible final step is to close the second valve 5. This is necessary in the case of a simple valve 7. This is not necessary in the case of a check valve 6, which closes itself when the pressure stops.

[0070] Compared to a dilution rinsing process, the implementation times are drastically reduced for a sweep rinsing method. For example, rinsing a given tank by dilution requires 1919 seconds to reach a residual concentration of 4% of the old gas, whereas it can be carried out, for the same tank, by sweeping, in 53 seconds to reach the same concentration. Similarly, rinsing the same tank by dilution requires 3755 seconds to reach a residual concentration of 0.4% of the old gas, whereas it can be carried out, for the same tank, by sweeping, in 100 seconds to reach the same concentration.

[0071] There appears to be a substantial advantage, in terms of time, and therefore of costs, in proceeding according to the invention, by scanning.

[0072] The invention has been illustrated and described in detail in the preceding drawings and description. The latter is to be considered illustrative and given by way of example. and not as limiting the invention to this single description. Numerous embodiments are possible. List of reference signs

[0073] 1: reservoir,

[0074] 2: first fluidic device,

[0075] 3: second fluidic device,

[0076] 4: first valve,

[0077] 5: second valve,

[0078] 6: non-return valve,

[0079] 7: simple valve,

[0080] 8: first extremity,

[0081] 9: second end,

[0082] 10: diffuser,

[0083] 11: cannula,

[0084] 12: front,

[0085] 13: light,

[0086] 14: cavity,

[0087] 15: fin,

[0088] 16: hat,

[0089] 17: driving,

[0090] A: axis,

[0091] a, [3 : angle.

Claims

Demands

1. A reservoir (1) for pressurized gas, such as hydrogen, characterized in that it comprises a diffuser (10) shaped to inject a pressurized gas into the reservoir (1) and in that the diffuser (10) is disposed inside the reservoir (1).

2. Reservoir (1) according to claim 1, wherein the diffuser (10) comprises at least one cannula (11) extending it and making, with the diffuser (10), an angle (a) of less than 90°.

3. Reservoir (1) according to claim 2, wherein said at least one cannula (11) comprises at least two cannulas (11) angularly equidistant around the diffuser (10).

4. Reservoir (1) according to claim 3, wherein said at least two cannulas (11) are not coplanar with the diffuser (10) so as to swirl the injected gas.

5. Reservoir (1) according to any one of claims 2 to 4, wherein said at least one cannula (11) is circular at 360° around the diffuser (10).

6. Reservoir (1) according to any one of claims 2 to 5, wherein said at least one cannula (11) is rotatable around the diffuser (10).

7. Reservoir (1) according to any one of the preceding claims, comprising a first fluidic device (2), having at least a first valve (4) suitable for drawing from the reservoir (1) and a second fluidic device (3) having at least a second valve (5) suitable for filling the reservoir (1), wherein the second fluidic device (3) includes the diffuser (10).

8. Tank (1) according to the preceding claim, wherein the first fluidic device (2) is disposed at a first end (8) of the tank (1) and the second device (3) is disposed at a second end (9) of the tank (1) opposite the first end (8).

9. A method for rinsing a tank (1) by sweeping according to any one of the two preceding claims, using rinsing equipment, characterized in that it comprises the following steps: - connecting an outlet of the rinsing equipment to the second valve (5) and connecting an inlet of the rinsing equipment to the first valve (4), simultaneously or in any order, - opening of the first valve (4) and possible opening of the second valve (5), simultaneously or in any order, - sending of the new pressurized gas via the outlet of the rinsing tool and recovery of the outgoing gas via the inlet of the rinsing tool, for a predetermined rinsing time, - closing of the first valve (4), - cessation of gas delivery when the desired gas pressure is reached in the tank (1), - possible closure of the second valve (5).

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