Method for filling liquid refrigerant trailer

Abstract

At the liquid cryogen warehouse, the large trailer is pressurized using gaseous cryogen from the short trailer that is not fully filled such that liquid cryogen flows from the large trailer to the empty trailer by the pressure difference.

Description

Technical Field

[0001] The present invention relates to a method for optimizing the distribution of liquid cryogen between liquefied cryogen warehouses and end users. Background Art

[0002] Liquid cryogens, such as hydrogen, are produced and stored by a variety of means, but typically liquid hydrogen is stored in cryogenic tanks located on or near a source of hydrogen liquefaction (i.e., a liquefier), and typically also on or near a source of raw hydrogen (such as an electrolyzer). The liquid hydrogen is transferred from the cryogenic storage container to a cryogenic tube trailer, which is transported by a semi-trailer truck to a site remote from the liquefier, such as a hydrogen refueling station for a fuel cell electric vehicle (FCEV).

[0003] At the remote site, liquid hydrogen is transferred from the tube trailer through the hose to the end-user tank by pressure differential. For safety purposes, the pressure in the tube trailer is limited by the regulatory agency, so the initial pressure in the tube trailer at the remote site is typically much less than the pressure in the end-user tank. Therefore, according to conventional technology, pressure must be accumulated in the tube trailer to reach a level sufficient to drive the liquid hydrogen from the tube trailer into the end-user tank. The transfer of liquid hydrogen then continues until the pressure in the tube trailer and the end-user tank is approximately equalized.

[0004] Because a significant portion of the final cost of liquid hydrogen consists of transportation costs between the liquefier and the remote site, it is desirable to reduce these transportation costs. One way to do this is to use so-called large trailers, which have a liquid hydrogen storage capacity that significantly exceeds the liquid hydrogen storage capacity of tube trailers. While the use of large trailers may be advantageous, regulatory agencies may restrict their use in densely populated areas for safety reasons.

[0005] Whether a tube trailer or a large trailer is used, if sufficient liquid hydrogen remains in the trailer after the initial filling, subsequent filling can be performed on other end-user tanks at other remote sites. Once the tube trailer or large trailer is sufficiently depleted of liquid hydrogen, the trailer is returned to the liquefier so that it can be filled again for continued delivery to the remote site.

[0006] Prior to refilling, depending on the cost of hydrogen versus the cost of compressed hydrogen, the gaseous hydrogen in the trailer may be vented to some point in the liquefaction process, typically until the pressure in the trailer reaches 2-4 psig. G. Petipas, “Boil-off losses along LH2 pathway,” Lawrence Livermore National Laboratory, LLNL-TR-750685, May 2, 2018. Depending on the relative costs of cooling, compression, and hydrogen product, the hydrogen may instead be vented to the environment. This is because the hydrogen left in the trailer upon return to the liquefier may have a relatively high temperature and / or relatively low pressure, thus making it difficult to take advantage of the thermodynamic advantages of its pressure and / or cold energy when introducing the remaining hydrogen into the liquefaction process.

[0007] In view of the foregoing, it would be advantageous to provide an improved method for distributing liquid hydrogen to one or more end-user sites that reduces the cost of transporting the liquid hydrogen and avoids waste. Summary of the invention

[0008] A method for distributing liquid cryogen to one or more end-user sites is disclosed. The method includes the following steps. A first, second, and third liquid cryogen-containing trailer are provided. The storage capacity of the first trailer and the third trailer is substantially the same and is less than the storage capacity of the second trailer. Each trailer has a headspace filled with cryogen vapor above the liquid cryogen contained therein. Each trailer is located at a warehouse, where the initial pressure of the first trailer is higher than the initial pressure of the second trailer, and the initial pressure of the second trailer is higher than the initial pressure of the third trailer. The headspaces of the first trailer and the second trailer are placed in flow communication, thereby balancing the pressure of the first trailer and the second trailer to a pressure P1 that is between the initial pressures of the first trailer and the second trailer and higher than the initial pressure of the third trailer. After the first trailer and the second trailer are pressure-equalized, the liquid refrigerant contained in the second trailer is placed in flow communication with the liquid refrigerant contained in the third trailer, causing the liquid refrigerant to flow from the second trailer to the third trailer due to the pressure difference between the pressure P1 of the first trailer and the second trailer and the initial pressure of the third trailer. The flow of liquid refrigerant between the second trailer and the third trailer is allowed to continue until the third trailer is substantially full of liquid refrigerant and the first trailer and the second trailer are each at pressure P2.

[0009] The method may include one or more of the following:

[0010] -Before the step of providing the first, second and third liquid refrigerant-containing trailers, transporting the first trailer to the end-user site A, where the liquid refrigerant is transferred from the first trailer to a storage tank at the end-user site A; and after the liquid refrigerant is transferred to the end-user site A, transporting the first trailer to a warehouse where the second trailer and the third trailer are located, wherein, at the warehouse, the initial pressure of the first trailer is higher than the initial pressure of the second trailer, and the initial pressure of the second trailer is higher than the initial pressure of the third trailer.

[0011] -After the step of allowing the flow of liquid refrigerant between the second trailer and the third trailer to continue until the third trailer is substantially full, transporting the third trailer to end user site B, where the liquid refrigerant is transferred from the third trailer to a storage tank at end user site B that is the same as or different from end user site A.

[0012] - after the step of allowing the liquid refrigerant to flow between the second trailer and the third trailer to continue until the third trailer is substantially full, discharging the gaseous refrigerant from the first trailer, thereby reducing the pressure of the first trailer to a predetermined pressure below P2; providing a fourth liquid refrigerant containing trailer having a storage capacity substantially the same as the first trailer and the third trailer, the fourth trailer being located at the warehouse at an initial pressure and having a head space filled with refrigerant vapor above the liquid refrigerant contained therein, the initial pressure of the fourth trailer being higher than P2 which is higher than the predetermined pressure of the first trailer; placing the fourth trailer in flow communication with the head space of the second trailer, thereby filling the fourth trailer with the gaseous refrigerant; The pressure of the fourth trailer and the second trailer is balanced to an intermediate pressure between P2 and the initial pressure of the fourth trailer, the intermediate pressure of the fourth trailer and the second trailer being higher than the predetermined pressure of the first trailer; after the pressure of the fourth trailer and the second trailer are balanced, the liquid refrigerant contained in the second trailer is placed in flow communication with the liquid refrigerant contained in the first trailer, so that the liquid refrigerant flows from the second trailer to the third trailer due to the pressure difference between the intermediate pressure of the first trailer and the second trailer and the predetermined pressure of the first trailer; and the flow of the liquid refrigerant between the second trailer and the first trailer is allowed to continue until the first trailer is substantially filled with the liquid refrigerant.

[0013] -Transporting the first trailer to end-user site C, where the liquid refrigerant is transferred from the first trailer to a storage tank at end-user site C, which is the same as or different from end-user site A and the same as or different from end-user site B, wherein the second trailer and the fourth trailer are the same or different trailers.

[0014] - after the step of allowing the liquid refrigerant to flow between the second trailer and the third trailer to continue until the third trailer is substantially full, discharging the gaseous refrigerant from the first trailer, thereby reducing the pressure of the first trailer to a predetermined pressure lower than P2; providing a fourth liquid refrigerant containing trailer having a storage capacity substantially the same as that of the first trailer and the third trailer, the fourth trailer being located at an initial pressure at the warehouse and having a head space filled with refrigerant vapor above the liquid refrigerant contained therein, the initial pressure of the fourth trailer being higher than P2 which is higher than the predetermined pressure of the first trailer; placing the head spaces of the fourth trailer and the second trailer in flow communication, thereby filling the fourth trailer with a gaseous refrigerant; The trailer and the second trailer are pressure balanced to an intermediate pressure between P2 and the initial pressure of the fourth trailer, the intermediate pressure of the fourth trailer and the second trailer being higher than the predetermined pressure of the first trailer; after the fourth trailer and the second trailer are pressure balanced, the liquid refrigerant contained in the second trailer is placed in flow communication with the liquid refrigerant contained in the first trailer, so that the liquid refrigerant flows from the second trailer to the third trailer due to the pressure difference between the intermediate pressure of the first trailer and the second trailer and the predetermined pressure of the first trailer; and the flow of the liquid refrigerant between the second trailer and the first trailer is allowed to continue until the first trailer is substantially filled with the liquid refrigerant.

[0015] -Transporting the first trailer to end-user site C, where the liquid refrigerant is transferred from the first trailer to a storage tank at end-user site C, which is the same as or different from end-user site A and the same as or different from end-user site B, wherein the second trailer and the fourth trailer are the same or different trailers.

[0016] - after the step of allowing the liquid refrigerant to flow between the second trailer and the third trailer to continue until the third trailer is substantially full, discharging the gaseous refrigerant from the first trailer, thereby reducing the pressure of the first trailer to a predetermined pressure lower than P2; providing a fourth liquid refrigerant containing trailer having a storage capacity substantially the same as that of the first trailer and the third trailer, the fourth trailer being located at an initial pressure at the warehouse and having a head space filled with refrigerant vapor above the liquid refrigerant contained therein, the initial pressure of the fourth trailer being higher than P2 which is higher than the predetermined pressure of the first trailer; placing the head spaces of the fourth trailer and the second trailer in flow communication, thereby filling the fourth trailer with a gaseous refrigerant; The trailer and the second trailer are pressure balanced to an intermediate pressure between P2 and the initial pressure of the fourth trailer, the intermediate pressure of the fourth trailer and the second trailer being higher than the predetermined pressure of the first trailer; after the fourth trailer and the second trailer are pressure balanced, the liquid refrigerant contained in the second trailer is placed in flow communication with the liquid refrigerant contained in the first trailer, so that the liquid refrigerant flows from the second trailer to the third trailer due to the pressure difference between the intermediate pressure of the first trailer and the second trailer and the predetermined pressure of the first trailer; and the flow of the liquid refrigerant between the second trailer and the first trailer is allowed to continue until the first trailer is substantially filled with the liquid refrigerant.

[0017] The first trailer is transported to end-user site C, where the liquid refrigerant is transferred from the first trailer to a storage tank at end-user site C, which is the same as or different from end-user site A and the same as or different from end-user site B, wherein the second trailer and the fourth trailer are the same or different trailers.

[0018] -After the step of allowing the flow of liquid refrigerant between the second trailer and the third trailer to continue until the third trailer is substantially full, the third trailer is transported to end-user site B, where the liquid refrigerant is transferred from the first trailer to a storage tank at end-user site B that is the same as or different from end-user site A.

[0019] -The refrigerant is hydrogen. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] For a further understanding of the nature and purpose of the present invention, reference should be made to the following detailed description in conjunction with the accompanying drawings, in which like elements are given the same or similar reference numerals, and in which:

[0021] Figure 1 It is a schematic diagram of the initial state of the three-trailer combination, where the three trailers include a high-pressure return trailer, a large trailer, and a low-pressure trailer to be filled.

[0022] Figure 2 yes Figure 1 Schematic diagram of the pressure equalization steps between the return trailer and the large trailer.

[0023] Figure 3 is to transfer liquid hydrogen from large trailers to Figure 2 Schematic diagram of the steps of the low pressure trailer.

[0024] Figure 4 Yes Figure 3 Schematic diagram of the liquid hydrogen transfer steps.

[0025] Figure 5 yes Figure 4 Schematic diagram of the end of the liquid hydrogen transfer step.

[0026] Figure 6 is a schematic diagram of the steps for venting the return trailer to reduce its pressure.

[0027] Figure 7 It is a schematic diagram of how the exhaust return trailer reaches the low pressure to be filled.

[0028] Figure 8 yes Figure 5 The return trailer and large trailer with Figure 7 Schematic diagram of the initial state of the combination of returning to the trailer now to be filled at low pressure.

[0029] Fig. 9 yes Figure 8 Schematic diagram of the pressure equalization steps between the return trailer and the large trailer.

[0030] Fig.10 is to transfer liquid hydrogen from large trailers to Fig. 9 Schematic diagram of the steps of the low pressure trailer.

[0031] Fig.11 Yes Fig.10 Schematic diagram of the liquid hydrogen transfer steps.

[0032] Fig.12 yes Fig.11 Schematic diagram of the end of the liquid hydrogen transfer step. DETAILED DESCRIPTION

[0033] The inventors have devised an optimized method for distributing liquid cryogen (such as nitrogen, argon, helium or hydrogen) to one or more end-user sites. The method utilizes at least three, typically four (or even more) liquid cryogen containment trailers, and the method includes steps performed at a liquid cryogen warehouse and steps performed at one or more end-user sites.

[0034] One of the trailers, the so-called large trailer, has a significantly larger storage capacity and is located at the warehouse. The other trailers are filled with liquid cryogen from the large trailer at the warehouse and, after filling, are transported to the end-user site so that they can in turn fill storage tanks located at the end-user site. The type of cryogen is not limited and includes oxygen, nitrogen, argon, helium, krypton, neon, and preferably hydrogen.

[0035] When one of the other trailers has been substantially depleted of liquid refrigerant and cannot be used to fill the end-user tanks, the trailer is returned to the warehouse. The interior of the trailer that returns to the warehouse may be at a relatively high pressure due to a heat leak in one of the other trailers during transportation between the end-user site and the warehouse and / or the need to increase the pressure in the trailer to achieve the filling of the end-user tanks. By pressure balancing the return trailer and the large trailer, the relatively high pressure in the return trailer is used to increase the pressure in the large trailer. Subsequently, the pressure in the return trailer and the pressure in the large trailer are used to drive the liquid refrigerant from the large trailer to the other trailer to be filled at a relatively low pressure.

[0036] In this way, most of the pressurized gaseous refrigerant remaining in the trailer after the liquid refrigerant is delivered to the end user site can be used during the filling of the liquid refrigerant from the large trailer to another trailer. Therefore, less refrigerant is wasted.

[0037] The method is explained in more detail below.

[0038] like Figure 1 As shown, a liquid refrigerant containing tube trailer, referred to as trailer 1, contains a relatively low amount of liquid refrigerant and is at a relatively high pressure, for example, 3.5-6 bara or about 3.8 bara, after delivering the liquid refrigerant to an end-user site (referred to as end-user site A) and being transported to a liquid refrigerant warehouse. There is another liquid refrigerant containing trailer at the warehouse, referred to as trailer 2. Trailer 2 is generally referred to as a so-called "large trailer" in the field of liquefied gases, and its liquid refrigerant storage capacity is higher than the liquid refrigerant storage capacity of trailer 1, which is generally referred to as a "short trailer". For example, the capacity of trailer 1 is typically about 36m 3 , and the capacity of trailer 2 is typically 75-80m 3 There is another liquid refrigerant container trailer at the warehouse, referred to as trailer 3. Each of trailers 1, 2, and 3 has a headspace filled with refrigerant vapor above the liquid refrigerant contained therein. At the warehouse, the initial pressure of trailer 1 is higher than the initial pressure of trailer 2, and the initial pressure of trailer 2 is higher than the initial pressure of trailer 3. Trailers 1 and 3 have substantially the same capacity. This means that trailer 1 and trailer 3 are designed to hold the same amount of liquid refrigerant, although there may be slight differences in their storage capacities.

[0039] Trailer 2 typically travels between a liquefaction plant and a warehouse where the refrigerant is liquefied, and is used as the primary means of filling short trailers (including trailer 1 and trailer 3). As will be seen below, trailer 3 is typically the one that previously served as trailer 1 in the following Figures 1 to 7 Trailer 1 is located at the warehouse because after delivering the liquid refrigerant to end-user site A, the amount of liquid refrigerant contained in trailer 1 is insufficient to deliver a suitable amount of refrigerant to another end-user site.

[0040] like Figure 2 It can be seen that after connecting the port formed in trailer 1 adjacent to its headspace with the port formed in trailer 2 adjacent to its headspace using suitable pipes / conduits, the headspaces of trailers 1 and 2 are placed in flow communication by operating one or more valves associated with the pipes / conduits connecting the ports of trailers 1 and 2. This allows trailers 1 and 2 to reach pressure balance, which of course will cause them to have a common pressure between the initial pressures in trailer 1 and trailer 2 before pressure balance is reached. For example, if the pressure of trailer 1 is 3.8 bara and the pressure of trailer 2 is 1.7 bara before pressure balance, the pressure in trailer 1 can be reduced from 3.8 bara to 3.6 bara, while the pressure in trailer 2 can be increased from 1.7 bara to 3.6 bara. This common pressure is also greater than the pressure in trailer 3.

[0041] like Figure 3 It can be seen that a port formed in trailer 2 adjacent to its bottom is connected with a port formed in trailer 3 adjacent to its bottom using a suitable pipe / conduit, and trailer 2 and trailer 3 are placed in flow communication by operating one or more valves associated with the pipe / conduit connecting the ports of trailer 2 and trailer 3. It should be noted that at this time, the headspaces of trailer 1 and trailer 2 are in flow communication. This allows liquid refrigerant to flow from trailer 2 to trailer 3 because there is a pressure difference between the pressure in trailer 1 and trailer 2 on the one hand and the pressure in trailer 3 on the other hand. It should be noted that by operating one or more valves associated with the headspace of trailer 3, the gaseous refrigerant in the headspace of trailer 3 is allowed to vent so that the pressure in trailer 3 is kept substantially constant to allow liquid refrigerant to flow from trailer 2 to trailer 3 in a relatively unimpeded manner and to prevent the pressure in trailer 3 from increasing. When liquid refrigerant flows from trailer 2 to trailer 3, there is space in trailer 2 that needs to be filled with gaseous refrigerant, and gaseous refrigerant will continue to flow from trailer 1 to trailer 2.

[0042] like Figures 4 to 5As can be seen, this transfer of liquid refrigerant from trailer 2 to trailer 3 is allowed to continue until the third trailer is substantially full of liquid refrigerant and trailers 1 and 2 are each at pressure P2. If the pressure difference between trailers 1 and 2 on the one hand and trailer 3 on the other hand is insufficient to allow trailer 3 to be charged with liquid refrigerant to a desired level, the booster circuit associated with trailer 1, the booster circuit associated with trailer 2, or each of the booster circuits may be operated to increase the pressure within trailers 1 and 2 sufficient to force sufficient liquid refrigerant into trailer 3. Typically, the liquid refrigerant continues to flow until each of trailers 1, 2, and 3 reaches pressure equilibrium. Alternatively, the flow may continue until the amount of liquid refrigerant within trailer 3 reaches a desired level, as determined by any suitable technique in the industrial gas field (such as a level sensor or a weighing scale). For example, if the pressure within trailer 1 and trailer 2 is 3.6 bara and the pressure within trailer 3 is 1.1 bara before operating one or more valves associated with the pipes / conduits connecting trailer 2 and trailer 3, then after trailer 3 is substantially filled with liquid refrigerant from trailer 2, the pressure within trailer 1 and trailer 2 decreases from 3.6 bara to 2.7 bara and the pressure within trailer 3 remains at 1.1 bara.

[0043] After being substantially full, one or more valves associated with the pipe / conduit connecting trailer 2 and trailer 3 are operated to disallow flow communication between trailer 2 and trailer 3. In addition, gaseous refrigerant is prevented from venting from the head space of trailer 3 by operating one or more valves associated with the head space of trailer 3. Next, the pipe / conduit connecting trailer 2 and trailer 3 is disconnected. Trailer 3 can now be transported to end-user site B, where liquid refrigerant is transferred from trailer 3 to a storage tank at end-user site B that is the same as or different from end-user site A.

[0044] Alternatively, if Figure 6 It can be seen that the pressure in the headspace of trailer 1 can be vented to a suitable level to allow it to be more easily filled with liquid refrigerant from trailer 2 in the same manner as described above for filling trailer 3 by pressure differential. For example, if the pressure in trailer 1 is 1.8 bara after filling trailer 3 with liquid refrigerant from trailer 2, the gaseous refrigerant in the headspace of trailer 1 can be vented until the pressure in trailer 1 reaches 1.1 bara. Due to the pressure differential described above, this reduced pressure allows trailer 1 to be filled with liquid refrigerant without having to use a booster circuit, or without having to use a booster circuit to a greater extent than would be the case if the filling was not pre-vented.

[0045] Alternatively, if Figures 7 to 12It can be seen that trailer 1 assumes the role previously performed by trailer 3 and is substantially filled with liquid cryogen in a similar manner.

[0046] like Figure 8 It can be seen that the liquid refrigerant containing tube trailer referred to as trailer 4 contains a relatively low amount of liquid refrigerant and is at a relatively high pressure, for example, 3.5-6 bara or about 3.8 bara, after delivering the liquid refrigerant to the end-user site referred to as end-user site C (which may be the same or different from site A and the same or different from site B) and being transported to the liquid refrigerant warehouse. Trailer 2 and trailer 1 are also located in the warehouse. Like trailer 2 and trailer 1, trailer 4 has a head space filled with refrigerant vapor above the liquid refrigerant it contains. At the warehouse, the initial pressure of trailer 4 is higher than the initial pressure of trailer 2, and the initial pressure of trailer 2 is higher than the initial pressure of trailer 1. Trailers 4 and 1 have substantially the same capacity. This means that trailer 4 and trailer 1 are designed to contain the same amount of liquid refrigerant, although there may be slight differences in their storage capacity.

[0047] As seen above, trailer 1 previously served as trailer 4 in the following Figures 8 to 12 Trailer 4 is located at the warehouse because, after delivering the liquid refrigerant to end-user site C, trailer 4 does not contain enough liquid refrigerant to deliver a suitable amount of refrigerant to another end-user site.

[0048] like Fig. 9 It can be seen that after connecting the port formed in trailer 4 adjacent to its headspace with the port formed in trailer 2 adjacent to its headspace using suitable pipes / conduits, the headspaces of trailer 4 and trailer 2 are placed in flow communication by operating one or more valves associated with the pipes / conduits connecting the ports of trailer 4 and trailer 2. This allows trailers 4 and 2 to reach pressure balance, which of course will cause them to have a common pressure between the initial pressures in trailer 4 and trailer 2 before pressure balance is reached. For example, if the pressure of trailer 4 is 3.8 bara before pressure balance, and the pressure of trailer 2 is 1.8 bara, the pressure in trailer 4 can be reduced from 3.8 bara to 2.8 bara, while the pressure in trailer 2 can be increased from 1.8 bara to 2.8 bara. This common pressure is also greater than the pressure in trailer 1.

[0049] like Fig.10It can be seen that the port formed in trailer 2 adjacent to its bottom is connected with the port formed in trailer 1 adjacent to its bottom using suitable pipes / conduits, and trailer 2 and trailer 1 are placed in flow communication by operating one or more valves associated with the pipes / conduits connecting the ports of trailer 2 and trailer 1. It should be noted that at this time, the head space of trailer 4 and trailer 2 is in flow communication. This allows liquid refrigerant to flow from trailer 2 to trailer 1 because there is a pressure difference between the pressure in trailer 4 and trailer 2 on the one hand and the pressure in trailer 1 on the other hand. It should be noted that by operating one or more valves associated with the head space of trailer 1, the gaseous refrigerant in the head space of trailer 1 is allowed to vent so that the pressure in trailer 1 remains substantially constant to allow liquid refrigerant to flow from trailer 2 to trailer 1 in a relatively unimpeded manner and to prevent the pressure in trailer 1 from increasing. When liquid refrigerant flows from trailer 2 to trailer 1, there is space in trailer 2 that needs to be filled with gaseous refrigerant, and gaseous refrigerant will continue to flow from trailer 4 to trailer 2.

[0050] like Figure 11 to Figure 12 As can be seen, this transfer of liquid refrigerant from trailer 2 to trailer 1 is allowed to continue until the third trailer is substantially full of liquid refrigerant and trailer 4 and trailer 2 are each at pressure P2. If the pressure difference between trailer 4 and trailer 2 on the one hand and trailer 1 on the other hand is insufficient to allow trailer 1 to be charged with liquid refrigerant to a desired level, the booster circuit associated with trailer 4, the booster circuit associated with trailer 2, or each of the booster circuits described above can be operated to increase the pressure within trailer 4 and trailer 2 sufficient to force sufficient liquid refrigerant into trailer 1. Typically, the liquid refrigerant continues to flow until each of trailer 4, trailer 2, and trailer 1 reaches pressure equilibrium. Alternatively, the flow can continue until the amount of liquid refrigerant within trailer 1 reaches a desired level, as determined by any suitable technology in the industrial gas field (such as a level sensor or a weighing scale). For example, if the pressure within trailer 4 and trailer 2 was 2.8 bara and the pressure within trailer 1 was 1.1 bara before operating one or more valves associated with the pipes / conduits connecting trailer 2 and trailer 1, then after trailer 1 is substantially filled with liquid refrigerant from trailer 2, the pressure within trailer 4 and trailer 2 is reduced from 2.8 bara to 2.3 bara and the pressure within trailer 1 is maintained at 1.1 bara.

[0051] After being substantially filled, one or more valves associated with the pipe / conduit connecting trailer 2 and trailer 1 are operated to disallow flow communication between trailer 2 and trailer 1. In addition, gaseous refrigerant is prevented from venting from the head space of trailer 1 by operating one or more valves associated with the head space of trailer 1. Next, the pipe / conduit connecting trailer 2 and trailer 1 is disconnected. Trailer 1 can now be transported to end-user site D, where liquid refrigerant is transferred from trailer 3 to a storage tank at end-user site D that is the same as or different from end-user site A, end-user site B, and end-user site C.

[0052] Alternatively, one of ordinary skill in the art will recognize that the above method may be repeated as desired, with the initial high pressure trailer being vented to a suitable level to allow for easier charging of liquid cryogen from trailer 2 via the pressure differential.

[0053] Embodiments of the present invention provide numerous advantages.

[0054] Without the present invention, the large trailer needs to be pressurized to force the liquid cryogen to flow from the large trailer to the short trailer. The technician will understand that conventionally, this pressurization is produced by gasifying the liquid cryogen in the large trailer. In contrast, the embodiment of the present invention utilizes the gaseous cryogen from the short trailer to pressurize the large trailer. By avoiding pressurizing the liquid cryogen by gasification, more cryogen (e.g., in the case of cryogenic hydrogen, about 170kg) can be used to transfer to the short trailer. Utilizing this liquid cryogen improves the efficiency of the supply chain and reduces losses because its heat content is lower than the liquid cryogen filled into the short trailer by conventional technology. Since the entire amount of liquid cryogen is transferred in this step, the supply chain efficiency is improved. Another angle is to reduce losses (using the above-mentioned cryogenic hydrogen example, a loss of about 170kg is reduced). The gas in the short trailer will be discharged, so capturing the gas to pressurize the large trailer prevents the generation of additional gas that must be discharged in the large trailer.

[0055] Although the present invention has been described in conjunction with specific embodiments of the present invention, it is obvious that, in view of the foregoing description, many alternatives, modifications and variations will be clear to those skilled in the art. Therefore, it is intended to include all such alternatives, modifications and variations that fall within the spirit and broad scope of the appended claims. The present invention can suitably include disclosed elements, be composed of disclosed elements or be substantially composed of disclosed elements, and can be implemented in the absence of undisclosed elements. In addition, if there is language related to sequence, such as first and second, it should be understood in an exemplary sense rather than in a restrictive sense. For example, it will be appreciated by those skilled in the art that some steps can be combined into a single step.

[0056] The singular forms "a," "an," and "the" include plural referents unless the context clearly dictates otherwise.

[0057] “Comprising” in the claims is an open transition term, which means that the subsequently identified claim elements are a non-exclusive list, i.e., anything else may be additionally included and remain within the scope of “comprising.” “Comprising” is defined herein to necessarily encompass the more restrictive transition terms “consisting essentially of” and “consisting of;” thus “comprising” may be replaced by “consisting essentially of” or “consisting of” and remain within the clearly defined scope of “comprising.”

[0058] "Providing" in the claims is defined to mean supplying, furnishing, making available, or preparing something. The step may instead be performed by any actor in the absence of explicit language in the claims.

[0059] Optional or optionally means that the subsequently described event or circumstance may or may not occur. The description includes examples where the event or circumstance occurs and examples where the event or circumstance does not occur.

[0060] Ranges may be expressed herein as from about one particular value and / or to about another particular value. When such a range is expressed, it is to be understood that another embodiment is from the one particular value and / or to the other particular value, along with all combinations within said range.

[0061] All references identified herein are each hereby incorporated by reference into this application in their entirety, and for the specific information for which each reference is cited, the specific information is provided.

Claims

1. A method of distributing liquid cryogen to one or more end-user sites, the method comprising the steps of: Providing first, second and third liquid cryogen-containing trailers, wherein the storage capacity of the first trailer and the third trailer is substantially the same and less than the storage capacity of the second trailer, each of the trailers having a headspace filled with cryogen vapor above the liquid cryogen contained therein, each of the trailers being located at a warehouse, at which the initial pressure of the first trailer is higher than the initial pressure of the second trailer, and the initial pressure of the second trailer is higher than the initial pressure of the third trailer; Placing the headspaces of the first trailer and the second trailer in fluid communication to pressure-equalize the first trailer and the second trailer to a pressure P1 that is between the initial pressures of the first trailer and the second trailer and higher than the initial pressure of the third trailer; After the pressure balancing of the first trailer and the second trailer, the liquid refrigerant contained in the second trailer is placed in flow communication with the liquid refrigerant contained in the third trailer, so that due to the pressure difference between the pressure P1 of the first trailer and the second trailer and the initial pressure of the third trailer, the liquid refrigerant flows from the second trailer to the third trailer, and the flow of liquid refrigerant between the second trailer and the third trailer is allowed to continue until the third trailer is substantially filled with liquid refrigerant and the first trailer and the second trailer are each at pressure P2.

2. The method of claim 1, further comprising the steps of: Prior to the step of providing the first, second and third liquid cryogen-containing trailers, the first trailer is transported to an end-user site A, where the liquid cryogen is transferred from the first trailer to a storage tank at the end-user site A; as well as After the liquid refrigerant is transferred to the end-user site A, the first trailer is transported to a warehouse where the second trailer and the third trailer are located, wherein, at the warehouse, the initial pressure of the first trailer is higher than the initial pressure of the second trailer, and the initial pressure of the second trailer is higher than the initial pressure of the third trailer.

3. The method of claim 2, further comprising the steps of: After the step of allowing the flow of liquid refrigerant between the second trailer and the third trailer to continue until the third trailer is substantially full, the third trailer is transported to end user site B, where the liquid refrigerant is transferred from the third trailer to a storage tank at end user site B that is the same as or different from end user site A.

4. The method of claim 3, further comprising the steps of: after said step of allowing said flow of liquid refrigerant between said second trailer and said third trailer to continue until said third trailer is substantially full, discharging gaseous refrigerant from said first trailer to a predetermined pressure less than P2; providing a fourth liquid refrigerant containing trailer having substantially the same storage capacity as the first trailer and the third trailer, the fourth trailer being located at the warehouse at an initial pressure and having a head space filled with refrigerant vapor above the liquid refrigerant contained therein, the initial pressure of the fourth trailer being higher than P2 which is higher than the predetermined pressure of the first trailer; Placing the headspace of the fourth trailer in fluid communication with the second trailer so as to balance the pressure of the fourth trailer and the second trailer to an intermediate pressure between P2 and the initial pressure of the fourth trailer, the intermediate pressure of the fourth trailer and the second trailer being higher than the predetermined pressure of the first trailer; as well as After the fourth trailer and the second trailer are pressure balanced, the liquid refrigerant contained in the second trailer is placed in flow communication with the liquid refrigerant contained in the first trailer, so that the liquid refrigerant flows from the second trailer to the third trailer due to the pressure difference between the intermediate pressure of the first trailer and the second trailer and the predetermined pressure of the first trailer, and the flow of liquid refrigerant between the second trailer and the first trailer is allowed to continue until the first trailer is substantially filled with liquid refrigerant.

5. The method of claim 4, further comprising the steps of: The first trailer is transported to an end-user site C, where the liquid refrigerant is transferred from the first trailer to a storage tank at the end-user site C, which is the same as or different from the end-user site A and the same as or different from the end-user site B, wherein the second trailer and the fourth trailer are the same or different trailers.

6. The method of claim 2, further comprising the steps of: after said step of allowing said flow of liquid refrigerant between said second trailer and said third trailer to continue until said third trailer is substantially full, discharging gaseous refrigerant from said first trailer to a predetermined pressure less than P2; providing a fourth liquid refrigerant containing trailer having substantially the same storage capacity as the first trailer and the third trailer, the fourth trailer being located at the warehouse at an initial pressure and having a head space filled with refrigerant vapor above the liquid refrigerant contained therein, the initial pressure of the fourth trailer being higher than P2 which is higher than the predetermined pressure of the first trailer; Placing the headspace of the fourth trailer in fluid communication with the second trailer so as to balance the pressure of the fourth trailer and the second trailer to an intermediate pressure between P2 and the initial pressure of the fourth trailer, the intermediate pressure of the fourth trailer and the second trailer being higher than the predetermined pressure of the first trailer; as well as After the fourth trailer and the second trailer are pressure balanced, the liquid refrigerant contained in the second trailer is placed in flow communication with the liquid refrigerant contained in the first trailer, so that the liquid refrigerant flows from the second trailer to the third trailer due to the pressure difference between the intermediate pressure of the first trailer and the second trailer and the predetermined pressure of the first trailer, and the flow of liquid refrigerant between the second trailer and the first trailer is allowed to continue until the first trailer is substantially filled with liquid refrigerant.

7. The method of claim 6, further comprising the steps of: The first trailer is transported to an end-user site C, where the liquid refrigerant is transferred from the first trailer to a storage tank at the end-user site C, which is the same as or different from the end-user site A and the same as or different from the end-user site B, wherein the second trailer and the fourth trailer are the same or different trailers.

8. The method of claim 1, further comprising the steps of: after said step of allowing said flow of liquid refrigerant between said second trailer and said third trailer to continue until said third trailer is substantially full, discharging gaseous refrigerant from said first trailer to a predetermined pressure less than P2; providing a fourth liquid refrigerant containing trailer having substantially the same storage capacity as the first trailer and the third trailer, the fourth trailer being located at the warehouse at an initial pressure and having a head space filled with refrigerant vapor above the liquid refrigerant contained therein, the initial pressure of the fourth trailer being higher than P2 which is higher than the predetermined pressure of the first trailer; Placing the headspace of the fourth trailer in fluid communication with the second trailer so as to balance the pressure of the fourth trailer and the second trailer to an intermediate pressure between P2 and the initial pressure of the fourth trailer, the intermediate pressure of the fourth trailer and the second trailer being higher than the predetermined pressure of the first trailer; as well as After the fourth trailer and the second trailer are pressure balanced, the liquid refrigerant contained in the second trailer is placed in flow communication with the liquid refrigerant contained in the first trailer, so that the liquid refrigerant flows from the second trailer to the third trailer due to the pressure difference between the intermediate pressure of the first trailer and the second trailer and the predetermined pressure of the first trailer, and the flow of liquid refrigerant between the second trailer and the first trailer is allowed to continue until the first trailer is substantially filled with liquid refrigerant.

9. The method of claim 8, further comprising the steps of: The first trailer is transported to an end-user site C, where the liquid refrigerant is transferred from the first trailer to a storage tank at the end-user site C, which is the same as or different from the end-user site A and the same as or different from the end-user site B, wherein the second trailer and the fourth trailer are the same or different trailers.

10. The method of claim 9, further comprising the steps of: After the step of allowing the flow of liquid refrigerant between the second trailer and the third trailer to continue until the third trailer is substantially full, the third trailer is transported to end user site B, where the liquid refrigerant is transferred from the first trailer to a storage tank at end user site B that is the same as or different from end user site A.

11. The method of claim 1, wherein: The cryogen is hydrogen.

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