Apparatus and method for delivering cryogenic fluid

Abstract

A method and apparatus for conveying cryogenic fluid, comprising: a first storage tank (2) for dispensing cryogenic fluid; a second storage tank (3) for containing cryogenic fluid; a fluid conveying circuit connecting the first storage tank (2) and the second storage tank (3), the conveying circuit including a first conduit (4) connecting an upper portion of the first storage tank (2) and an upper portion of the second storage tank (3) and including at least one valve (5), the conveying circuit including a second conduit (6) connecting a lower portion of the first storage tank (2) to the second storage tank (3), the second conduit (6) including a pump (7) including an inlet connected to the first storage tank (2) and an outlet connected to the second storage tank (3), and the pump (7) and at least one valve (5) of the first conduit (4) being configured to fluidly communicate the upper portion of the first storage tank (2) and the upper portion of the second storage tank (3) by opening the at least one valve (5) during the conveying of liquid from the first storage tank (2) to the second storage tank (3) by the pump (7).

Description

[0001] The present invention relates to an apparatus and method for conveying cryogenic fluids into liquefied gas storage containers.

[0002] More specifically, the present invention relates to an apparatus for conveying cryogenic fluid, the apparatus comprising: a first storage tank for dispensing cryogenic fluid, the first storage tank storing cryogenic fluid having a lower liquid phase and an upper gas phase; a second storage tank for containing cryogenic fluid including a lower liquid phase and an upper gas phase; and a fluid conveying circuit connecting the first and second storage tanks, the conveying circuit including a first conduit connecting the upper portions of the first and second storage tanks and including at least one valve, and the conveying circuit including a second conduit connecting the lower portion of the first storage tank to the second storage tank.

[0003] To fill liquid hydrogen storage tanks from mobile storage tanks (semi-trailers), a system that transports the liquid by pressure differential is typically used. Typically, the storage container to be filled is at a pressure between 1.0 and 13 bar absolute pressure (typically 3 bar absolute pressure), and the liquid contained in the transport tank is at a pressure between 1.0 and 13 bar absolute pressure. To achieve this transport by pressure differential, in most cases, the tank of the transport semi-trailer first needs to be pressurized to a pressure typically 1 bar higher than the pressure in the stationary storage container to be filled.

[0004] Currently, atmospheric pressure heaters are typically placed under transport semi-trailers to allow pressurization and transfer of the semi-trailer's contents to receiving tanks.

[0005] This system has several drawbacks. Performance is difficult to control because it is highly dependent on weather conditions (temperature, wind, humidity). Furthermore, stratification (gas temperature increasing with altitude) that occurs in the gas headspace of the transport semi-trailer can easily heat the liquid hydrogen being transported to the customer (especially in the case of multiple transports). Consequently, the quality of the transported hydrogen is lower. Additionally, depending on the level in the transport tank, the need to pressurize the transport semi-trailer's tank before commencing transport can last from 15 to 60 minutes.

[0006] Other known solutions use pumps to transfer liquid from one storage container to another. However, the use of pumps necessitates the installation of an atmospheric pressure heater to compensate for the volume of liquid discharged with gas from the heater.

[0007] Furthermore, current transfer pump technology has other drawbacks. Therefore, by pumping liquid, the pump adds heat to the fluid being transferred, and as the pumping flow rate decreases, the pump may be damaged due to cavitation within the cryogenic liquid. Additionally, the pump provides a considerable flow rate into the customer's storage tank. As a result, a large amount of gas must be vented to make room for this incoming liquid volume.

[0008] The purpose of this invention is to remedy all or part of the disadvantages of the prior art described above.

[0009] Therefore, a substantial feature of the device according to the invention, which in other respects also conforms to its general definition given in the preamble above, is that the second pipeline includes a pump having an inlet connected to the first tank and an outlet connected to the second tank, and that the pump and at least one valve of the first pipeline are configured to fluidly communicate the upper portion of the first tank and the upper portion of the second tank by opening the at least one valve during the pumping of liquid from the first tank to the second tank.

[0010] Furthermore, embodiments of the present invention may have one or more of the following features:

[0011] - The second pipeline includes an end that connects the lower portion of the first tank to the lower portion of the second tank.

[0012] - The second pipeline includes an end that connects the lower portion of the first tank to the upper portion of the second tank.

[0013] - The second storage tank includes a system for pressurizing the storage tank, the system including piping connecting the lower and upper portions of the storage tank and equipped with a heater and a set of one or more valves.

[0014] The present invention also relates to a method for conveying cryogenic fluid between a first storage tank and a second storage tank of an apparatus for distributing cryogenic fluid according to any one of the above or below features, the method comprising the steps of: conveying liquid from the first storage tank to the second storage tank by a pump, and simultaneously, fluidly communicating the upper portion of the first storage tank and the upper portion of the second storage tank by opening at least one valve of a first conduit.

[0015] Based on other possible specific characteristics:

[0016] - During the step of transferring liquid from the first storage tank to the second storage tank by a pump, the liquid is transferred to the lower liquid section and / or the upper gas section of the second storage tank.

[0017] - The method includes the following steps prior to the liquid delivery step: equalizing the pressure between the first and second storage tanks, during which at least one valve in the first pipeline is opened to fluidly connect only the upper portions of the first and second storage tanks.

[0018] - The process of maintaining the same pressure between the first and second storage tanks is continued until the pressure difference between the two tanks reaches a predetermined threshold, for example, between 0 and 1 bar.

[0019] - The method includes the following steps concurrently with the step of transferring liquid from the first storage tank to the second storage tank via a pump: pressurizing the second storage tank and / or the first storage tank,

[0020] - The pressurization step is performed by a system for pressurizing the second or first tank, the system including piping connecting the lower and upper portions of the tank and having a set of one or more valves and heaters.

[0021] The present invention may also relate to any alternative apparatus or method that includes any combination of the above or the following features within the scope of the claims.

[0022] Further specific features and advantages will become apparent from the following description provided with reference to the accompanying drawings, in which:

[0023] [ Figure 1 A schematic partial view illustrating the structure and operation of an example of the device according to the invention in a first possible step of use is shown;

[0024] [ Figure 2 The same device is shown in another operating configuration.

[0025] [ Figure 3 The same device is shown in another operating configuration.

[0026] [ Figure 4 A schematic partial view illustrating the structure and operation of another possible example of a device according to the invention is shown.

[0027] The apparatus 1 for conveying cryogenic fluids includes a first storage tank 2 for distributing the cryogenic fluid, such as a mobile storage tank 2 mounted on a semi-trailer. Conventionally, the first storage tank 2 stores a cryogenic fluid, such as hydrogen, which is in a liquid phase in the lower part and in a gaseous phase in the upper part.

[0028] The apparatus 1 includes a second storage tank 3 for receiving the same fluid, which is, for example, fixed and contains or is intended to contain a cryogenic fluid that is in a liquid phase in its lower portion and a gaseous phase in its upper portion. The apparatus 1 includes a fluid delivery loop capable of connecting the first storage tank 2 and the second storage tank 3. This delivery loop includes a first conduit 4, the two ends of which are respectively connected to the upper portions of the first storage tank 2 and the upper portions of the second storage tank 3. The first conduit 4 includes at least one valve 5 (preferably at least two valves connected in series), and one end of the first conduit is connected to the second storage tank 3. The first conduit includes a detachable connecting member to allow continuous connection to various storage tanks supplying fluid.

[0029] The delivery loop includes a second conduit 6 that connects the lower portion of the first tank 2 to the second tank 3 (in the upper and / or lower portions). In the illustrated example, the second conduit 6 includes two downstream ends connected to the lower and upper portions of the second tank 3, respectively. The second conduit 6 includes a pump 7 with an inlet connected to the first tank 2 and an outlet connected to the second tank 3. This second conduit 6 preferably includes a set of one or more valves for interrupting or allowing the flow of liquid from the first tank 2 to the second tank 3. As described above, at least at one or more downstream ends of the second conduit connected to the second tank 3, the second conduit 6 includes detachable connecting members to allow continuous connection to various tanks to be supplied.

[0030] As described in more detail below, the pump 7 and the first pipeline 4 are configured to fluidly communicate the upper portion (gas phase) of the first tank 2 and the upper portion (gas phase) of the second tank 3 during the transfer of liquid from the first tank 2 to the second tank 3 by the pump 7.

[0031] Connecting the gas headspaces of the two tanks 2 and 3 during pumping improves the thermal and hydraulic efficiency of fluid transport through an optimized sequence procedure. This makes the use of an atmospheric pressure heater on the first tank 2 optional and allows for the advantageous use of the gas headspace of the second tank 3, while improving the quality of the transported molecules and the volumetric efficiency of transport.

[0032] Therefore, when pump 7 circulates liquid from first tank 2 to second tank 3, second pipe 6 allows "excess" gas present in second tank 3 to circulate back to first tank 2 via pressure differential, specifically to fill the volume left due to liquid extraction.

[0033] The following section will describe usage examples.

[0034] In the case of transporting liquefied gases (such as hydrogen), the first storage tank 2 can reach the location of the second storage tank 3. The first storage tank 2 has an internal pressure, for example, between 1 and 6 bar absolute pressure. The operator can connect the two storage tanks 2 and 3 using the first pipe 4 and the second pipe 6. After this connection is completed, all valves are closed.

[0035] Preferably, the pipes 4 and 6 are then inertized and / or flushed and / or cooled.

[0036] Open one or more valves 5 on the first pipe 4. Make the pressure equal between the two storage tanks 2 and 3 (see [...]). Figure 1 ]).

[0037] Preferably, pump 7 can be started when the pressure difference between the two storage tanks 2 and 3 decreases to near 0 bar (or, for example, to a certain value below 1 bar).

[0038] This allows the pressure in the second tank 3 to be utilized to increase the pressure at the pump inlet and optimize the NPSH (inlet pressure drop) of pump 7.

[0039] The point at which the pressures of the two tanks 2 and 3 are equal can be the intermediate pressure between the two initial pressures in the two tanks 2 and 3, typically between 2 bar and 8 bar. This equal pressure depends particularly on the initial pressures in the two tanks 2 and 3, their liquid levels, and their respective volumes. The pressure in the first tank 2 will typically be slightly lower than the pressure in the second tank 3. The pump can then be started and the corresponding valve opened to deliver the liquid (see […]). Figure 2 ]).

[0040] Pump 7 is preferably configured to compensate for pressure drop in the liquid line (second line 6) and the gas line (first line 4). In particular, the first line 4 may be insulated to reduce pressure drop.

[0041] If the NPSH of pump 7 becomes insufficient during delivery, an atmospheric pressure heater (see, for example, located at the location of the second tank 3 (or on the first tank 2 or both)) may be optionally used. Figure 3 This is to pressurize the gas top space of the two storage tanks 2 and 3, which are connected by fluid communication.

[0042] For example, the second storage tank 3 includes a pressurization system 8, which includes pipes connecting the lower and upper parts of the storage tank, and is equipped with a set of one or more valves and an atmospheric pressure heater (heat exchanger).

[0043] Pump 7 is preferably a single-stage or multi-stage centrifugal pump, wherein a specific velocity is selected to improve isentropic efficiency under relatively small pressure differentials. The pump can be installed on the first storage tank 2 or at the location of the second storage tank 3, preferably installed in an insulated container or directly integrated into the internal structure of the insulated storage tanks 2 and 3. The electric power of the pump is preferably less than 10 kW.

[0044] For example, pump 7 could be a type of pump that pumps cryogenic liquids and is partially submerged in a cold box (with the pump motor outside the cold box), or a type of pump that is completely insulated (vacuum insulated) within the cold box. For example, pump 7 could be submerged in a fluid reservoir (tank), i.e., a relatively small, dedicated intermediate liquid storage tank (e.g., a cryostat type). Similarly, pump 7 could be (at least partially) directly submerged in one of the two aforementioned tanks 2 and 3 (in which case the pump is at least partially integrated into the tank). Any other arrangement of one or more pumps is conceivable.

[0045] Therefore, despite its low cost and simple structure, the present invention offers many advantages.

[0046] Therefore, because the evaporated gas from the second storage tank 3 is used in addition to the transfer pump 7, the introduction of heat into the system is minimized. Pump 7 provides only a small pressure differential (a few bar). Therefore, evaporation (vaporization) losses are minimal in the logistics chain. The gas headspace of the second storage tank 3 is advantageously utilized. This gas is not vented.

[0047] Furthermore, the quality of the transported molecules is improved (due to lower transport temperatures). Multiple transports using a single mobile tank 2 are more efficient. This solution eliminates the need for liquid consumption for pressurization. Additionally, reduced pressurization time leads to reduced braking time.

[0048] This solution allows for potentially increased flow rates while maintaining relatively stable pumping conditions. Furthermore, the flow rate is independent of weather conditions. This solution essentially reduces or eliminates cryogenic fog and liquid oxygen condensation beneath the mobile transport tank 2.

[0049] In addition, the procedures for transport operators have been simplified.

[0050] The two tanks 2 and 3 operate at relatively low pressures, which potentially allows for a reduction in mechanical size limitations (resulting in savings in weight, materials, cooling time, and cost).

[0051] Therefore, it is no longer necessary to equip the first storage tank 2 with an atmospheric pressure heater, or the size of the latter can be greatly reduced.

[0052] The power consumption of the liquid transfer pump 7 is significantly lower than that of the gas compressor that can be used on the pipe 4 connecting the two gas headspaces, especially because the conditions (especially the temperature) at the compressor inlet are more variable than those at the pump inlet.

[0053] exist[ Figure 4 In the embodiment shown, device 1 includes a third pipe 9 that connects the first pipe 4 to the lower portion of the first storage tank 2. This third pipe 9 may be part of a delivery loop and / or may belong to the first storage tank 2.

[0054] As shown in the figure, this third pipeline 9 is preferably equipped with a valve 19, such as an isolation valve, which allows the gaseous gas in the second storage tank 3 to be depressurized to the liquid phase of the first storage tank 2 in the open position. That is, this third pipeline 9 can allow vapor from the second storage tank 3 (via the first pipeline 4) to be recovered into the liquid phase of the first storage tank 2 (and for the vapor to condense).

[0055] After this pressure balance is achieved, the liquid can be drawn from the first storage tank 2 via the second pipeline 6 (and pump 7).

[0056] This could result in heating the liquid phase in the first tank 2, but in some applications this may be expected and beneficial (e.g., at a pressure of 5 bar).

Claims

1. A method for conveying cryogenic fluid using an apparatus for conveying cryogenic fluid, the apparatus comprising: First storage tank (2), which is used to distribute cryogenic fluid, the first storage tank (2) stores cryogenic fluid having a lower liquid phase and an upper gas phase; A second storage tank (3) containing a cryogenic fluid comprising a lower liquid phase and an upper gas phase; a fluid transport circuit connecting the first storage tank (2) and the second storage tank (3), the fluid transport circuit including a first pipe (4) connecting the upper portion of the first storage tank (2) and the upper portion of the second storage tank (3) and including at least one valve (5); the fluid transport circuit including a second pipe (6) connecting the lower portion of the first storage tank (2) to the second storage tank (3), the second pipe (6) including a pump (7) including an inlet connected to the first storage tank (2) and a connection to... The outlet of the second storage tank (3), and at least one valve (5) of the pump (7) and the first pipeline (4) are configured to fluidly communicate the upper portion of the first storage tank (2) and the upper portion of the second storage tank (3) by opening the at least one valve (5) during the pumping of liquid from the first storage tank (2) to the second storage tank (3), the method ensuring the delivery of cryogenic fluid between the first storage tank (2) and the second storage tank for distributing cryogenic fluid, the method comprising the steps of: delivering liquid from the first storage tank (2) to the second storage tank (3) by the pump (7), and simultaneously The method, characterized in that, prior to the liquid delivery step, comprises the following steps: equalizing the pressure between the first tank (2) and the second tank (3), during which, by opening at least one valve (5) of the first pipe (4), fluid communication is established only between the upper portions of the first tank (2) and the upper portions of the second tank (3), and during the step of delivering liquid from the first tank (2) to the second tank (3) by the pump (7), The liquid is delivered to the lower liquid portion and / or upper gas portion of the second tank (3), and the second conduit (6) includes an end connecting the lower portion of the first tank (2) to the lower portion of the second tank (3), and the second conduit (6) includes an end connecting the lower portion of the first tank (2) to the upper portion of the second tank (3); the method includes the following steps prior to the step of delivering liquid from the first tank (2) to the second tank (3) by the pump (7): equalizing the pressure of the upper portion of the second tank (3) and the lower portion of the first tank (2).

2. The method as described in claim 1, characterized in that, The step of maintaining the same pressure between the first storage tank (2) and the second storage tank (3) is maintained until the pressure difference between the first storage tank (2) and the second storage tank (3) reaches the determined threshold.

3. The method as described in claim 2, characterized in that, The threshold is between 0 and 1 bar.

4. The method according to any one of claims 1 to 3, characterized in that, The method includes the step of pressurizing the second tank (3) and / or the first tank (2) while the liquid is transported from the first tank (2) to the second tank (3) by the pump (7).

5. The method as described in claim 4, characterized in that, The pressurization step of the second tank (3) and / or the first tank (2) is performed by a system (8) for pressurizing the second tank (3) or the first tank (2), the system comprising a pipe connecting the lower and upper portions of the second tank (3) or the first tank (2) and provided with a set of one or more valves and heaters.

6. The method according to any one of claims 1 to 5, characterized in that, The second storage tank (3) includes a system (8) for pressurizing the second storage tank (3), the system including a pipe connecting the lower part and the upper part of the second storage tank (3) and provided with a heater and a set of one or more valves.

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