Apparatus and method for storing and distributing cryogenic fluid

Abstract

To provide an apparatus for storing and distributing cryogenic fluid, such as liquid hydrogen.SOLUTION: An apparatus comprises a cryogenic reservoir which is buried below the ground, and a liquid withdrawal circuit connected to the reservoir with a downstream end located above the ground and designed to be connected to a consumer. The withdrawal circuit comprises a cryogenic pump arranged above the ground. The apparatus comprises a pipe for the recovery of vaporization gas generated inside the pump, having a downstream end connected to the reservoir. The pipe for the recovery of the vaporization gas comprises at least one device for controlling the pressure and / or flow rate of the vaporization gas returned to the reservoir. The device for controlling the pressure and / or flow rate is configured to control the pressure inside the reservoir at a pressure level which is greater than the pressure at the inlet of the pump.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to an apparatus and method for storing and distributing cryogenic fluids, more particularly to an apparatus for storing and distributing cryogenic fluids, such as liquid hydrogen, comprising a cryogenic storage chamber buried underground, and a liquid intake circuit having an upstream end connected to the storage chamber and a downstream end located above ground and designed to be connected to consumers, the intake circuit comprising a cryogenic pump arranged above ground, the apparatus comprising a pipe for collecting vaporized gas produced inside the pump, the pipe having an upstream end connected to the pump and a downstream end connected to the storage chamber. [Background technology]

[0002] The space requirements for storing hydrogen are a major problem. One solution is underground storage. However, connecting buried cryogenic storage facilities to aboveground filling pumps creates the problem of supplying these pumps during their various operational phases. Supplying the pumps with liquid is traditionally done by gravity, by having sufficient liquid height in the storage facility so that it reaches the pump inlet correctly. Furthermore, at cryogenic fuel stations, the pumps need to be cooled at start-up, causing evaporation of some of their supply (vaporized gas, "boil-off gas" or BOG). This vaporized gas is usually returned to the storage facility by a line that conducts the gas toward the top of the storage facility. If the storage facility is above the pump, this return occurs naturally. This function is more difficult to provide in configurations where the high point of the storage facility is lower than the pump inlet. Summary of the Invention

[0003] SUMMARY OF THE INVENTION An object of the present invention is to remedy all or some of the above-mentioned drawbacks of the prior art.

[0004] For this reason, the device according to the invention, and also according to the general definition given in the preamble above, is essentially characterized in that the pipe for recovering the vaporized gas comprises at least one device for controlling the pressure and / or flow rate of the vaporized gas returned to the storage chamber, the device for controlling the pressure and / or flow rate being configured to control the pressure inside the storage chamber to a pressure level greater than the pressure at the inlet of the pump.

[0005] This arrangement ensures the operation of the storage facility's pumps by making it possible to recover vapors from them in order to reduce the overall losses of the station, and to guarantee the correct supply of the pumps.

[0006] Furthermore, embodiments of the invention may include one or more of the following features: - the device for controlling pressure and / or flow rate is configured to control the pressure inside the storage chamber to a level between 5 mbar and 500 mbar above the pressure at the inlet of the pump, the device for controlling pressure and / or flow rate comprises at least one of a heater, a heat exchanger and a compressor, such as a low-temperature compressor, - the device for controlling pressure and / or flow comprises a heating heat exchanger and a compressor arranged in series, - the pipe for recovering the vapor comprises two separate passages in the heating heat exchanger, before and after compression in the compressor, for heating the vapor before compression and for cooling it before injection into the storage chamber, respectively; the pipe for recovering the vapor comprises a bypass from the heat exchanger and one or more valve assemblies configured to avoid at least a part of the flow of the vapor through the heat exchanger; - the pipe for collecting the vaporized gas is provided with a branched T-joint with a valve directed towards the discharge zone; - the device comprises a device for pressurizing the storage chamber, which is autonomous and separate from the pipe for collecting the vaporized gas and the device for controlling it; The present invention also relates to a method for drawing a fluid using a device according to any one of the above or following characteristics, characterized in that the method comprises the following steps: pumping a cryogenic fluid from a storage chamber via a pump, recovering vaporized gas produced in the area of the pump, compressing the recovered vaporized gas, and injecting the compressed gas into the storage chamber at a determined pressure.

[0007] According to further possible characteristics: - the step of compressing the recovered vapor is carried out by a cold compressor or by a non-cold compressor, the vapor being heated before compression in the case of a non-cold compressor; The step of compressing the recovered vapor is performed by a non-cryogenic compressor and further comprises the step of cooling the compressed vapor via heat exchange with a flow of vapor upstream of the compressor.

[0008] The invention also relates to any alternative device or method comprising any combination of the above or following features that fall within the scope of the claims.

[0009] Further features and advantages will become apparent from reading the following description, which proceeds with reference to the drawings.

[0010] The invention will be more clearly understood from reading the following description, given purely by way of example and made with reference to the accompanying drawings, in which: [Brief explanation of the drawings]

[0011] [Figure 1] 1 is a schematic diagram in vertical section showing an example of the structure and operation of a device according to the invention; DETAILED DESCRIPTION OF THE INVENTION

[0012] In all of the figures, the same reference symbols refer to the same elements.

[0013] In this detailed description, the following embodiments are examples. When this description refers to one or more embodiments, this does not mean that the feature applies only to a single embodiment. Single features of various embodiments can also be combined and / or interchanged to provide further embodiments.

[0014] The illustrated device 1 for storing and delivering cryogenic fluids can be used, for example, for liquid hydrogen, and comprises a cryogenic storage chamber 11 buried underground and a liquid intake circuit 20 having an upstream end connected to the storage chamber 11 and a downstream end located above ground and designed to be connected to a consumer.

[0015] The intake circuit 20 comprises a cryogenic pump 2 arranged on the ground. The device 1 comprises a pipe 3 for recovering the vaporized gas produced inside the pump 2, having an upstream end connected to the pump 2 and a downstream end connected to a storage chamber 11. This pipe 3 for recovering the vaporized gas comprises at least one device for controlling the pressure and / or flow rate of the vaporized gas returned to the storage chamber 11. This at least one device 8, 9 for controlling the pressure and / or flow rate is configured to control the pressure inside the storage chamber 11 to a pressure level greater than the pressure at the inlet of the pump 2.

[0016] The device for controlling pressure and / or flow rate is preferably configured to control the pressure inside the reservoir 11 above the pressure at the pump inlet, so as to exceed the hydrostatic height between the reservoir and the inlet of the pump 2. For example, the device for controlling pressure and / or flow rate is configured to control the pressure inside the reservoir to a level between 5 mbar and 500 mbar above the pump inlet pressure, for example between 5 mbar and 500 mbar above the pump inlet pressure. The device for controlling pressure and / or flow rate comprises at least one of a heater 8, a heat exchanger 7, and a compressor 9, e.g., a low-temperature compressor. For simplicity, FIG. 1 shows the aforementioned three components in series. Naturally, only one or two of them may be provided.

[0017] The device for controlling the pressure and / or flow rate may for example comprise or consist of a heating heat exchanger 7 in series with a compressor 9 .

[0018] The vapor produced by the pump 2 can be heated in the heat exchanger 7 and then returned to the storage chamber 11 .

[0019] The reservoir 11 can therefore be kept pressurized to provide an adequate supply to the pump 2. The relatively high pump 2 is therefore at a lower pressure than that of the reservoir 11. This lower pressure represents, for example, between 10 and 100 mbar, due to the pressure required to overcome the manometer height between the reservoir 11, the intake of the pump 2 and the pressure loss in the intake line. Recycling the vaporized gas of the pump 2 in the reservoir 11 makes it possible to compensate for this relative difference in pressure.

[0020] This architecture allows for the recovery of vapor produced by Pump 2 during its various stages of operation. When started, Pump 2 produces vapor in relatively large quantities. After cooling down, during its operation, Pump 2 produces vapor in reduced amounts, for example, due to leaks, heat input, etc.

[0021] These vapors can be collected and returned to the storage chamber 11 via a recovery pipe 3 .

[0022] This allows all or only a portion of these vaporized gases to be recovered during these various stages of operation.

[0023] The vapor is collected in a recovery pipe 3, heated in a heating heat exchanger 7 and compressed before being returned to the storage chamber. A compressor 9 makes it possible to circulate the vapor flow by compressing it to the pressure of the storage chamber, for example at a level of a few tens of millibars.

[0024] The compressed vapor may be returned to the heating heat exchanger 7 to be cooled before being re-injected into the storage chamber 11 .

[0025] If this heating heat exchanger 7 is not sufficient to heat the gas before compression (excessive flow rate of vaporized gas, excessively cold temperature at the inlet, etc.), a further (heating) heat exchanger 8 can be provided to complete the heating to a determined temperature (compressor ambient temperature or intake temperature).

[0026] This optional heater 8 is shown in dashed lines between the heating heat exchanger 7 and the compressor 9 .

[0027] As shown, a valve 5, such as an isolating valve, may be disposed in series between the pump 2 and the heating heat exchanger 7. Similarly, the valve 5 is preferably provided upstream of the pump 2. A valve 5 may also be provided between the heating heat exchanger 7 and the compressor 9.

[0028] Similarly, a check valve 4 may be provided upstream of the pump 2 .

[0029] As shown, the pipes for recovering the vaporized gas can be provided in two separate paths (preferably counter-flowing) in the heating heat exchanger 7 before and after compression in the compressor 9, respectively, to provide heating of the vaporized gas before compression and cooling of the compressed gas before injection into the storage chamber 11.

[0030] As shown diagrammatically, the pipe 3 for recovering the vapor may also comprise a bypass 13 from the heat exchanger and an assembly of one or more valves 23 configured to allow at least part of the vapor flow to avoid passing through the heat exchanger 7. For example, the bypass 13 may allow all or part of the compressed flow of vapor to avoid passing twice through the heating heat exchanger 7. This allows the temperature of the compressed vapor to increase before returning to the storage chamber 11 in order to stabilize the pressure in the storage chamber 11 if it increases too quickly.

[0031] As shown, the pipe 3 for recovering the vapor may also include a branched T-joint 33 with a valve towards the discharge zone, which may be located between the heating heat exchanger 7 and the inlet of the compressor 9.

[0032] The reservoir 11 may be equipped with an autonomous pressurization device 10 configured to increase its pressure when required (by drawing, heating and refilling fluid).

[0033] This recovery and recirculation of the vapor allows the storage chamber 11 to be maintained at an overpressure relative to the pump 2. This permanently guarantees correct intake to the pump 2. If the recovered vapor is insufficient to maintain a sufficiently high pressure during operation of the pump, the pressurization device 10 can be used to pressurize the storage chamber 11.

[0034] Naturally, the invention is not limited to the exemplary embodiment described above: thus, for example, the heating heat exchanger 7 and the compressor 9 can be replaced by a low-temperature compressor (which can compress gas at low temperatures without the need for prior heating).

Claims

1. A device for storing and distributing a cryogenic fluid, such as liquid hydrogen, comprising a cryogenic storage chamber (11) buried underground, and a liquid intake circuit (20) having an upstream end connected to the cryogenic storage chamber (11) and a downstream end located above ground and designed to be connected to a consumer, the liquid intake circuit (20) comprising a cryogenic pump (2) arranged above ground, the device (1) comprising a pipe (3) for recovering vaporized gas produced inside the cryogenic pump (2), the pipe having an upstream end connected to the cryogenic pump (2) and a downstream end connected to the cryogenic storage chamber (11), 1. The apparatus according to claim 1, wherein the pipe (3) for recovering the vaporized gas comprises at least one device (8, 9) for controlling the pressure and / or flow rate of the vaporized gas returned to the cryogenic storage chamber (11), the device (8, 9) for controlling the pressure and / or flow rate being configured to control the pressure inside the cryogenic storage chamber (11) to a pressure level greater than the pressure at the inlet of the cryogenic pump (2).

2. 2. The apparatus according to claim 1, characterized in that the device for controlling the pressure and / or flow rate is configured to control the pressure inside the cryogenic storage chamber to a level between 5 mbar and 500 mbar above the pressure at the inlet of the cryogenic pump (2).

3. 3. The apparatus according to claim 1 or 2, characterized in that the device (8, 9) for controlling the pressure and / or flow rate comprises at least one of a heater (8), a heat exchanger (7) and a compressor (9), for example a low-temperature compressor.

4. 4. Apparatus according to claim 3, characterized in that the device (8, 9) for controlling the pressure and / or flow rate comprises a heating heat exchanger (7) and a compressor (9) arranged in series.

5. 5. The device according to claim 4, characterized in that the pipe (3) for recovering the vaporized gas comprises two separate passages in the heating heat exchanger (7) before and after compression in the compressor (9) for heating the vaporized gas before compression and cooling it before injection into the cold storage chamber (11), respectively.

6. 6. The device according to claim 4 or 5, characterized in that the pipe (3) for recovering the vaporized gas comprises a bypass (13) from the heat exchanger (7) and an assembly of one or more valves (23) configured to allow at least a part of the flow of the vaporized gas to avoid passing through the heat exchanger (7).

7. 7. Device according to any one of claims 1 to 6, characterized in that the pipe (3) for recovering the vaporized gas comprises a branched T-junction (33) with a valve towards a discharge zone.

8. 8. The device according to any one of claims 1 to 7, characterized in that it comprises a device (10) for pressurizing the cryogenic storage chamber, which is autonomous and separate from the pipe (3) for recovering the vaporized gas and from the devices (8, 9) for controlling it.

9. 9. A method for drawing a fluid using a device according to any one of claims 1 to 8, characterized in that it comprises the following steps: pumping a cryogenic liquid from the cryogenic storage chamber via the cryogenic pump (2), recovering the vaporized gas produced in the area of the cryogenic pump (2), compressing the recovered vaporized gas, and injecting the compressed gas into the cryogenic storage chamber (11) at a determined pressure.

10. 10. The method of claim 9, wherein the step of compressing the recovered vaporized gas is performed by a low-temperature compressor or by a non-low-temperature compressor, and the vaporized gas is heated before compression in the case of the non-low-temperature compressor.

11. 11. The method of claim 10, wherein the step of compressing the recovered vapor is performed by a non-low temperature compressor, and further comprising the step of cooling the compressed vapor via heat exchange with a vapor stream upstream of the compressor (9).

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