Cryogenic containment system

Abstract

A cryogenic fluid containment system is disclosed. The system is capable of storing a fluid, such as hydrogen, at cryogenic temperatures and cryogenic pressures. Once the fluid naturally warms, the fluid may be directed to a portion of a liquefaction system configured to perform a cooling technique on the fluid. The cooling technique may be a Joule-Thomson cooling technique. The liquefaction system may be equipped to perform both non-Joule-Thomson and Joule-Thomson cooling techniques. The system is configured to direct the fluid to an appropriate portion of the liquefaction system, which may be based at least in part on the Joule-Thomson coefficient of the fluid.

Description

Technical Field

[0001] The present disclosure relates to systems and methods for handling fluids at cryogenic temperatures and cryogenic pressures. More particularly, the present disclosure relates to systems and methods for reducing or removing boil-off waste.

Background Art

[0002] Large-scale facilities such as data centers consume vast amounts of energy and require backup equipment to ensure sufficient power to complete essential operations in the event of a power outage. Traditionally, diesel generator sets or "power sets" have been used to supply backup power to large facilities. Hydrogen fuel cells and engines are increasingly being considered for this purpose, but they present their own challenges. The fuel for such engines is stored at cryogenic temperatures and pressures until backup power is needed. Cryogenic fluids are typically stored in tanks that passively maintain the stored fluid at cryogenic temperatures. In most cases, actively cooling fluids stored in such passive storage tanks is considered inefficient, and as a result, other systems are often used to cool these fluids before they are placed in the tanks. Passive storage tanks are, of course, imperfect, and cryogenic fluids stored in such tanks are gradually heated and pressure increases over time. When such heating occurs, at least some of the stored hydrogen needs to be released as a "boil-off" to maintain a safe pressure in the tank. It should be noted that boil-off refers to the natural process by which the amount of cryogenic fluid changes from the liquid phase to the gas phase as the temperature inside the storage tank rises. In some conventional systems, the amount of cryogenic fluid undergoing the phase change from liquid to gas provides passive cooling of the cryogenic fluid as the latent heat of vaporization absorbs thermal energy within the system. When this occurs, the gas produced via boil-off can be released into the atmosphere to maintain a safe storage pressure. In some systems, hydrogen can evaporate at a rate of up to 1% or more per day. In such systems, hydrogen needs to be completely replaced approximately every 100 days unless a process is employed to capture the boil-off and reuse it at least partially.

[0003] One system for transforming a boil-off stream of cryogenic fluid is disclosed in U.S. Patent No. 6,672,104 (hereinafter referred to as "Reference '104"). Reference '104 discloses pressurizing the boil-off stream, cooling the pressurized boil-off stream, and then expanding the boil-off stream. Further expansion of the boil-off stream, as described in Reference '104, cools it further and at least partially liquefies the boil-off stream. Reference '104 discloses a pre-selected bubble point temperature of the resulting pressurized liquid obtained by removing a first predetermined amount of one or more components having a vapor pressure greater than the vapor pressure of the stored cryogenic fluid from the boil-off stream. To obtain the pre-selected bubble point temperature, Reference '104 also describes adding a second predetermined amount of one or more additives having a molecular weight heavier than the molecular weight of the stored cryogenic fluid and a vapor pressure lower than the vapor pressure of the stored fluid to the boil-off stream.

[0004] The system described in reference '104' may be configured to controllably convert the boil-off stream of a stored cryogenic fluid, but the system requires the use of multiple components specialized for pressurizing, cooling, and expanding the stored fluid. Such components increase the cost and complexity of the system. Furthermore, such components are prone to failure over time. Thus, the system described in reference '104', and other similar systems, typically suffer from high maintenance costs associated with the repair and / or replacement of such components, and inefficiencies associated with corresponding maintenance downtime.

[0005] The examples in this disclosure are intended to overcome one or more of the aforementioned defects. [Overview of the project]

[0006] Examples of the present disclosure relate to a system comprising a storage tank, a liquefaction system, and a boil-off loop configured to store cryogenic hydrogen in a two-phase mixture. Specifically, the liquefaction system may include a Joule-Thomson cooling stage and a non-Joule-Thomson cooling stage fluidly connected to the Joule-Thomson cooling stage. Furthermore, the liquefaction system may be configured to receive hydrogen from an external source, receive hydrogen in the non-Joule-Thomson cooling stage, cool the hydrogen to a first temperature below a temperature threshold in the non-Joule-Thomson cooling stage, transfer the hydrogen from the non-Joule-Thomson cooling stage to the Joule-Thomson cooling stage at the first temperature, cool the hydrogen to a second temperature lower than the first temperature in the Joule-Thomson cooling stage, and transfer the hydrogen from the Joule-Thomson cooling stage to the storage tank at the second temperature. Furthermore, the boil-off loop may be configured to transfer boil-off hydrogen from the storage tank to the Joule-Thomson cooling stage of the liquefaction system. Thus, the Joule-Thomson cooling stage may be configured to cool the boil-off hydrogen to a third temperature and transfer the cooled boil-off hydrogen to the storage tank at the third temperature.

[0007] Further examples of the present disclosure relate to systems including a storage tank, a liquefaction system, and a controller. Specifically, the storage tank may be configured to store a fluid in a cryogenic state below a cryogenic threshold and below a cryogenic pressure threshold. Furthermore, the liquefaction system may include a first stage and a second stage fluid-connected to the first stage. Furthermore, the liquefaction system may be configured to receive the fluid in the first stage, reduce the fluid temperature to a storage temperature below the cryogenic threshold, and transfer the fluid from the second stage to the storage tank at the storage temperature and through the first fluid passage. In some examples, the second fluid passage may fluid-connect the storage tank to the second stage. Furthermore, a controller may be operably connected to the liquefaction system and one or more fluid control devices, and the controller is configured to cause one or more flow control devices to move the boil-off fluid from the storage tank to the second stage of the liquefaction system, liquefy the boil-off fluid in the second stage of the liquefaction system, and transfer the liquefied boil-off fluid from the second stage of the liquefaction system to the storage tank.

[0008] Further examples of the present disclosure relate to a method comprising determining the temperature of hydrogen stored in a storage tank using a first sensor associated with the storage tank, and determining the pressure of hydrogen using a second sensor associated with the storage tank. The method may further include determining, using a controller operably connected to the first and second sensors, that the hydrogen temperature exceeds a temperature threshold and that the hydrogen pressure exceeds a pressure threshold. The method may further include, using the controller and at least partially, based on determining that the hydrogen temperature exceeds a temperature threshold and that the hydrogen pressure exceeds a pressure threshold, directing boil-off hydrogen from the storage tank to a liquefaction system fluidly connected to the storage tank. The liquefaction system may include a first stage configured to perform non-Joule-Thomson cooling techniques and a second stage fluidly connected to the first stage, the second stage configured to perform Joule-Thomson cooling techniques. Thus, the method may include, using the controller, directing liquid hydrogen from the second stage of the liquefaction system to a storage tank to a second flow control device operably connected to the controller. [Brief explanation of the drawing]

[0009] [Figure 1] Figure 1 is a schematic diagram of a power system for a large-scale facility, as illustrated in the present disclosure. [Figure 2] Figure 2 is a schematic diagram of a cryogenic containment system associated with the power system of Figure 1, according to an example of the present disclosure. [Figure 3] Figure 3 is a schematic diagram of a cryogenic containment system associated with the power system of Figure 1, according to a further example of this disclosure. [Figure 4] Figure 4 is a schematic diagram of a multi-stage liquefaction system according to a further example of the present disclosure. [Figure 5] Figure 5 is a block diagram showing an example of a method according to the present disclosure. [Figure 6]Figure 6 is a block diagram showing a method according to a further embodiment of the present disclosure, in which a single liquefaction step is used for boil-off purposes. [Modes for carrying out the invention]

[0010] Figure 1 is a schematic diagram of a cryogenic fluid boil-off mitigation system 100 according to an embodiment of the present disclosure. The cryogenic fluid boil-off mitigation system 100 can be used with any fluid in any phase or combination of phases, at various temperatures and pressures, depending on the specific application of the fluid and type of fluid as required in each case. Hydrogen is one such fluid that can be stored and maintained by the cryogenic fluid boil-off mitigation system 100. Naturally, other fluids may also be used with the cryogenic fluid boil-off mitigation system 100 according to the present disclosure, and any specific reference to hydrogen does not limit the scope of the present disclosure to any type of fluid. For example, cryogenic fluids may include methane, carbon dioxide, nitrogen, helium, noble gases, and other elements / compounds.

[0011] Hydrogen can present specific challenges regarding storage. For example, hydrogen is volatile and has a low liquefaction temperature (approximately 33 Kelvin). Therefore, maintaining hydrogen in a safe and efficient manner so that it can be used as fuel or for other applications can be difficult. Naturally, in any storage system, hydrogen tends to warm up and even evaporate. When this happens, the internal pressure of the tank increases and, if left unchecked, will exceed containment measures. Consequently, the internal pressure can cause the tank to rupture, potentially leading to damage to surrounding facilities, equipment, personnel, and / or assets. In some cases, vaporized hydrogen can be released into the atmosphere to maintain the pressure level. Alternatively, or additionally, a cryogenic fluid boil-off mitigation system 100 can mitigate the losses associated with releasing stored hydrogen (or cryogenic fluid) into the atmosphere and also address the problem of pressure rise within the tank.

[0012] The cryogenic fluid boil-off mitigation system 100 can receive hydrogen via an intake mechanism 102, which is coupled to a hydrogen source 104 or otherwise supplied with hydrogen from the hydrogen source 104. Furthermore, the cryogenic fluid boil-off mitigation system may include a flow divider 106 configured to control the distribution of hydrogen from the hydrogen source 104 within the cryogenic fluid boil-off mitigation system 100, a liquefaction system 108 consisting of two or more cooling stages (e.g., cooling stage 1 110 and cooling stage 2 112) connected by an interstage conduit 114, and a storage tank 116. As described above, the liquefaction system 108 may include multiple cooling stages, such as cooling stage 1 110 and cooling stage 2 112, each of which may include one or more cooling systems. Furthermore, the flow divider 106 and / or other components of the cryogenic fluid boil-off mitigation system 100 may be controlled by an intake controller 118 that regulates the incoming hydrogen from the hydrogen source 104 and routes the incoming hydrogen to one or more destinations. As will be described in more detail below, such destinations may include cooling stage 1 110 along route A, cooling stage 2 along route B, and / or storage tank 116 along route C. Similarly, the tank controller 120 may be configured to regulate the extraction of boil-off from storage tank 116 and direct the boil-off to cooling stage 1 110 along route D. In some examples, the tank controller 120 is also configured to direct the boil-off to cooling stage 2 112 along route E. Thus, if the power demand associated with facility system 124 is not met by the primary power system 126, hydrogen (or another cryogenic fluid) can be stored for use by backup power system 122, and the various configurations of the cryogenic fluid boil-off mitigation system 100 described herein can help avoid the loss of hydrogen caused by boil-off.

[0013] The intake mechanism 102 may be any suitable mechanism through which hydrogen (or another cryogenic fluid) can be injected into and / or received by the cryogenic fluid boil-off mitigation system 100. In some examples, the hydrogen source 104 may include a delivery truck, a delivery pipeline, or any other suitable means of delivery from an external hydrogen source. Furthermore, the intake mechanism 102 may include valves, flanges, connectors, couplings, and other fastening means that enable the cryogenic fluid boil-off mitigation system 100 to be fluidly connected to the hydrogen source 104. In addition, the intake mechanism may include temperature sensors (e.g., thermocouples, thermometers, etc.), pressure sensors (e.g., absolute pressure, gauge pressure, differential pressure, etc.), flow sensors (e.g., velocity flow, mass flow, etc.), and / or other sensors configured to identify the characteristics of the incoming hydrogen. Similarly, the intake mechanism may include regulating systems such as a pump (e.g., a mechanism configured to induce fluid flow, generate a pressure difference, or otherwise assign work to the fluid), control valves (e.g., valves configured to open to allow fluid flow and close to restrict fluid flow in response to received signals and / or applied forces), throttle valves (e.g., valves used to control fluid flow rate and system pressure), and other pressure and flow control systems to control the pressure and flow of hydrogen to the cryogenic fluid boil-off mitigation system 100. In some additional examples, the hydrogen received from the hydrogen source 104 may be in a mixed-phase solution, in a gaseous state, or in a liquid state. Thus, the intake mechanism 102 may be configured to process the incoming fluid associated with different phase states, separate the gaseous phase from the liquid phase, and direct the different phase states to the appropriate parts of the cryogenic fluid boil-off mitigation system 100. In some further examples, the hydrogen source 104 may be a hydrolysis system (e.g., a system configured to react water and a substance to produce at least hydrogen in a chemical process), an electrolysis system (e.g., a system configured to provide an electric current that splits water into hydrogen and oxygen), and / or other hydrogen-producing systems. In some hydrolysis reactions, the substance and water can react such that the target molecule (or parent molecule) of hydrolysis obtains hydrogen ions.Furthermore, hydrogen can be generated by a chemical reaction and supplied to the intake mechanism 102. It should be noted that the intake mechanism 102 can receive hydrogen in any form and facilitate its inflow into the cryogenic fluid boil-off mitigation system 100.

[0014] The diversion valve 106 may be controlled by the intake controller 118 remotely via electronic input or directly via a servo / motor. The diversion valve may be configured to control the fluid flowing between the inlet connector (e.g., pipe, hose, tube, etc.) and one or more outlet connectors. As described above, one or more sensors (e.g., a temperature sensor, a pressure sensor, and a flow sensor, which are components of the intake mechanism 102) may generate one or more signals associated with the physical properties of the hydrogen received from the hydrogen source 104. One or more signals may be transmitted to the intake controller 118 and used for hydrogen regulation and routing. Alternatively, or additionally, the intake mechanism 102 may be accompanied by a delivery service such as a hydrogen vendor providing hydrogen at a known pressure and temperature. In some examples, the intake controller 118 may control the hydrogen It may be configured to monitor the temperature of hydrogen relative to the inversion temperature. It should be noted that the inversion temperature is the temperature at which the Joule-Thomson coefficient of hydrogen (or other cryogenic fluid) changes sign (for example, the Joule-Thomson coefficient is negative at temperatures above the inversion temperature, causing the fluid to heat up when it expands, and positive at temperatures below the inversion temperature, causing the fluid to cool when it expands). Therefore, if the intake controller 118 determines that the inflow temperature of hydrogen is above the inversion temperature, the intake controller 118 will direct the hydrogen to the diversion valve 106 to cooling step 1 along path A. The hydrogen is directed towards 110. Similarly, if the intake controller 118 determines that the hydrogen inflow temperature is below the inversion temperature, the intake controller 118 directs the diversion valve 106 to direct the hydrogen towards cooling stage 2 112 along path B. In some additional examples, the intake controller may determine that the hydrogen is below another threshold temperature lower than the inversion temperature and may be directed directly towards tank 116 along path C (for example, the hydrogen is below its condensation point for pressure and is liquid). In at least one example, the additional threshold temperature may be called the storage temperature, which indicates the temperature at which hydrogen can be safely introduced into storage tank 116 without increasing the temperature or pressure inside the storage tank 116.

[0015] In some further examples, the intake controller 118 can cause the flow diversion valve 106 to adjust and route the hydrogen received from the hydrogen source 104 along paths A, B, and C based on at least one or more temperature thresholds, one or more pressure thresholds, one or more flow thresholds, or a combination of various thresholds. Specifically, the temperature and pressure associated with the hydrogen received from the hydrogen source can be used to determine the amount of work required to cool the hydrogen and / or the hydrogen from the temperature and pressure of the hydrogen source 104 to the temperature and pressure of the storage tank 116. Thus, the intake controller 118 can direct the hydrogen received from the hydrogen source 104 to cooling stage 1 110 for initial cooling of the hydrogen, and to cooling stage 2 112 for additional cooling and / or liquefaction.

[0016] The cryogenic fluid boil-off mitigation system 100 may include a liquefaction system 108. Specifically, the liquefaction system 108 may include various components that reduce the temperature and / or pressure of the cryogenic fluid supplied to the liquefaction system 108 at different temperatures, pressures, and / or conditions. In the example shown, the liquefaction system 108 includes cooling stages 1 110 and 2 112. Cooling stage 1 110 can reduce the temperature of hydrogen 104 to the threshold temperature and / or threshold pressure of cooling stage 2 112 by utilizing non-Joule-Thomson effects and Joule-Thomson cooling techniques (where the Joule-Thomson coefficient is negative). In some examples, the threshold temperature (and threshold pressure) may be determined based on at least the inversion temperature of the cryogenic fluid (e.g., hydrogen), the storage temperature or storage pressure of the storage tank 116, the boil-off temperature and boil-off pressure associated with the boil-off of the storage tank 116, or other determined temperatures and pressures associated with the cryogenic fluid boil-off mitigation system 100. Furthermore, the cooling stage 2 112 can utilize Joule-Thomson cooling techniques to further reduce the temperature of the cryogenic fluid (e.g., hydrogen received from hydrogen source 104).

[0017] In some examples, non-Joule-Thomson cooling techniques may include any refrigeration cycle, or non-periodic refrigeration technique, that can reduce the temperature of a fluid (e.g., gas, liquid, etc.). Refrigeration cycles may include vapor compression cycles, absorption cycles, adsorption cycles, and other refrigeration techniques that periodically utilize work to remove thermal energy from the system (e.g., cooling hydrogen received from hydrogen source 104). Alternatively, or additionally, non-periodic refrigeration may include the use of a working fluid that is dispersed or discarded after cooling (e.g., liquid nitrogen is relatively inexpensive and can be released into the atmosphere after refrigeration use). As described above, cooling stage 110 can utilize non-Joule-Thomson techniques to cool hydrogen received from hydrogen source 104. Such techniques can utilize heat exchangers with different fluids in various flow paths that are in thermal contact with each other to transfer heat from one fluid to the other (optionally in a periodic or non-periodic cooling system). Some exemplary types of heat exchangers include shell-and-tube heat exchangers, plate heat exchangers, plate-and-shell heat exchangers, insulated wheel heat exchangers, pillow-plate-here exchangers, fluid heat exchangers, and dynamic scrape surface heat exchangers.

[0018] In some examples of cooling stage 1 110, non-Joule-Thomson cooling techniques are used to cool hydrogen, or another low inversion temperature fluid (e.g., helium, neon, etc.), to its inversion temperature. By lowering the temperature of hydrogen to below its inversion temperature, the Joule-Thomson effect can be used to cool hydrogen (or other cryogenic fluids). It should be noted that hydrogen and some other materials have a somewhat inherent property in the gas phase, with inversion temperatures below room temperature (approximately 20°C). Therefore, cooling stage 1 110 of the liquefaction system 108 may be configured to utilize non-Joule-Thomson effect cooling for all cryogenic fluids in cooling stage 1 110. Furthermore, cooling stage 1 110 of the liquefaction system 108 may be configured to utilize Joule-Thomson effect cooling in cooling stage 1 110 for cryogenic fluids having inversion temperatures above the operating temperature of cooling stage 1 110. The liquefaction system 108 may include an interstage conduit 114 through which hydrogen passes from stage 1 110 to stage 2 112, where Joule-Thomson cooling is performed to further reduce the temperature of the hydrogen 104.

[0019] Stage 2 112 of the liquefaction system 108 can further reduce the temperature of the hydrogen received from the hydrogen source 104 using the Joule-Thomson cooling technique. In some examples, the Joule-Thomson cooling technique can be used to produce liquid hydrogen from the hydrogen treated by cooling stage 1 110. The Joule-Thomson effect (also known as the Joule-Kelvin effect or Kelvin-Joule effect) describes the temperature change when a real gas or liquid (distinguishable from an ideal gas) is passed through a valve or porous plug while being insulated, so that no heat is exchanged with the environment when pressure is applied (for example, a cryogenic fluid undergoes adiabatic or substantially adiabatic expansion). This procedure is called a throttling process or a Joule-Thomson process. At room temperature, most gases are cooled when they expand using the Joule-Thomson technique. However, as mentioned above, some gases, such as hydrogen, helium, and neon, have inversion temperatures below room temperature, which heat up during expansion until the gas temperature falls below the inversion temperature. Therefore, the Joule-Thomson technique can be used for hydrogen, helium, and neon when cooled below the inversion temperature. There are many ways to achieve the desired Joule-Thomson cooling, including nozzles, valves, or porous plugs, and cooling stage 2 112 may include any number of these techniques. Furthermore, cooling stage 2 112 may include multiple cooling operations. In some embodiments, the multiple cooling operations may be stages that reduce the temperature. In some embodiments, cooling stage 2 112 may have multiple redundant cooling operations, and depending on the amount of hydrogen being cooled, parts of cooling stage 2 112 may be employed while other parts are idle.

[0020] In some examples, Figure 1 is a diagram of a cryogenic fluid boil-off mitigation system 100 for a facility according to an example of the present disclosure. Specifically, the cryogenic fluid boil-off mitigation system 100 may be configured to maintain cryogenic fluid that can be used as fuel by a backup power system 122. Furthermore, the cryogenic fluid boil-off mitigation system may be configured to prevent the release of boil-off from the storage tank 116 into the atmosphere by treating the boil-off by reliquefying it. Furthermore, the cryogenic fluid boil-off mitigation system may be configured to maintain cryogenic fluid as a power reserve in case the power demand of the facility system 124 is not met by the primary power system 126. In some additional examples, the primary power system 126 may be grid power from a local government or another standard primary power source. Furthermore, the facility system 124 may be associated with a power demand determined based on the power consumed by at least various systems within the facility. Therefore, power demand may include the power requirements of any and all powered HVAC systems, lighting, heating systems, cooling systems, motors, engines, networks, servers, other computing devices, and substantially any other mechanisms that consume power within the facility.

[0021] Furthermore, the cryogenic fluid boil-off mitigation system 100 can manage cryogenic fluid to the backup power supply 122 in the event of a power outage, shortage, or other situation resulting in a power demand for the facility system 124 that is not met by the primary power system 126. In some examples, the backup power system 126 may include a hydrogen-powered engine and / or fuel cell that converts hydrogen (or other cryogenic fuel) into enough energy to meet the power demand of the facility system 124. Thus, if it is determined that the power demand is not met by the primary power system 126, the facility and / or backup power system 122 may extract and consume hydrogen from the storage tank 116 to generate additional power for the facility system 124.

[0022] Figure 2 is a diagram of the potential operating space for a cryogenic fluid boil-off reduction system. Specifically, Figure 2 is an approximation of the phase diagram of diatomic hydrogen. However, it should be noted that Figure 2 is an approximation and that the various values and boundary lines for the individual phases may not be accurately mapped to real-world values. Figure 2 includes an approximation of the temperature and pressure at which the liquid phase 202 can vaporize / evaporate into the gas phase 204 and the gas phase 204 can condense into the liquid phase 202. As shown in Figure 2, an exemplary vaporization curve 206 can represent the boundary between the liquid phase 202 and the gas phase 204 of the cryogenic fluid. For example, the vaporization curve 206 can represent the combinations of real-world temperatures and pressures at which atoms or molecules of the cryogenic fluid can absorb the latent heat of vaporization or radiate the latent heat of condensation and transition between the liquid phase 202 and the gas phase 204. Similarly, the exemplary vaporization curve 206 can extend between a triple point 208 that represents the pressure and temperature at which the cryogenic fluid exists in equilibrium among the three states of matter (e.g., solid, liquid, and gas), and a critical point 210 that represents the pressure and temperature at which the liquid phase 202 and the gas phase of the cryogenic fluid become a supercritical fluid. Figure 2 includes an approximation of the triple point 208 and the critical point 210 of hydrogen, but it should be noted that the triple points and critical points of other fluids can occur at other combinations of temperature and pressure. Further, Figure 2 includes a first curve segment 212 that represents the first temperature change and the first pressure change associated with the cryogenic fluid caused by a first cooling operation (e.g., the cooling operation performed by the cooling stage 1 110 of Figure 1). Similarly, Figure 2 includes a second curve segment 214 that represents the second temperature change and the second pressure change associated with the cryogenic fluid caused by a second cooling operation (e.g., the cooling operation performed by the cooling stage 2 112 of Figure 1).

[0023] Despite the indication of the triple point 208 and critical point 210 in Figure 2, it should be noted that these phenomena have real-world temperatures and pressures associated with them. Specifically, the triple point of hydrogen, where solid, liquid, and gaseous phases 202 and 204 are in equilibrium, occurs at approximately 13.84 K / -259.31°C and 7.04 kPa / 0.0704 bar. Similarly, the critical point of hydrogen, where liquid and gaseous phases 202 and 204 cease to coexist and form a supercritical fluid, occurs at approximately 33.20 K / -239.95°C and 1300 kPa / 12.97 bar. Therefore, the vaporization curve 206 represents the temperature and pressure at which hydrogen in liquid phase 202 can vaporize into gaseous phase 204 and hydrogen in gaseous phase 204 can condense into liquid phase 202.

[0024] In some examples, the cryogenic fluid boil-off mitigation system described above with respect to Figure 1 can be configured to operate within the gas phase 204 and liquid phase 202 of the cryogenic fluid, as depicted in Figure 2. Specifically, cooling stages 110 and 212 can be configured to cool the hydrogen received from the hydrogen source 104 from the inflow temperature and liquefy the hydrogen for storage in the storage tank 116. Furthermore, the first cooling operation of cooling stage 110 may be represented by a first curve segment 212, in which the hydrogen temperature is reduced from the hydrogen inflow temperature below a temperature threshold 216 associated with the change in the Joule-Thomson coefficient from negative to positive. At atmospheric pressure, the Joule-Thomson coefficient changes from negative to positive at approximately 200 K / -73.15°C, although the temperature threshold 216 can be determined at least partially based on the pressure of the hydrogen. However, the first cooling operation associated with cooling stage 110 can be configured to reduce the hydrogen to below an arbitrary temperature threshold at a temperature higher than the vaporization curve 206. Furthermore, the first cooling operation may cause a pressure increase (as illustrated by the first curve segment 212 in Figure 2) in an isobaric environment, or it may cause a pressure decrease based at least in part on the type of cooling method utilized by cooling stage 1 110. Similarly, a second cooling operation associated with cooling stage 2 112 may be configured to reduce hydrogen from the discharge temperature of the first cooling operation to a storage temperature below the condensation temperature at a given pressure (as illustrated by the first curve segment 212 in Figure 2).

[0025] In some examples, an additional cooling operation (not shown) can be included between the first cooling operation associated with the first curve segment 212 and the second cooling operation associated with the second curve segment 214. Specifically, the first cooling operation is configured to reduce the temperature of hydrogen from the inlet temperature of a hydrogen source (e.g., a hydrogen tank, a hydrogen vendor, a hydrolysis system, an electrolysis system, etc.) to a first cooling operation discharge temperature lower than the temperature at which the Joule-Thomson coefficient changes from a negative value to a positive value, using non-Joule-Thomson cooling technology. Further, the non-Joule-Thomson cooling technology can increase, hold constant, or decrease the pressure of hydrogen with respect to the inlet pressure associated with the hydrogen source 104. After the first cooling operation, a pressurization operation (e.g., a pump) can increase the pressure from the first discharge pressure of the first cooling operation to the inlet pressure associated with the second cooling operation or the additional cooling operation. Thus, the additional cooling operation and the second cooling operation can cool hydrogen using Joule-Thomson cooling technology and liquefy the hydrogen for storage. Further, an additional pressurization operation may be included between the additional cooling operation, the second cooling operation, and / or the storage tank to maintain the integrity, safety, and operating parameters of the system.

[0026] In some additional examples, a second cooling operation, and if included, the additional cooling operation, may be configured to include one or more Joule-Thomson cooling operations (e.g., passing hydrogen through a throttle valve, a porous plug, or other depressurizing device that cools hydrogen) that reduce both the temperature and pressure of the hydrogen, as illustrated by the second curve segment 214. Furthermore, the second cooling operation may be configured to reduce the temperature of the hydrogen from the second cooling operation inlet temperature to the storage tank temperature, the second cooling operation inlet temperature being associated with the first cooling operation discharge temperature or the additional cooling operation discharge temperature (optionally, after the hydrogen discharge by the first or additional cooling operation has been pressurized). Furthermore, the second cooling operation may be further configured to receive hydrogen at a temperature and pressure approximately equal to the boil-off temperature threshold and / or boil-off pressure threshold of the storage tank. Thus, the second cooling operation may be configured to receive hydrogen at the second cooling operation inlet temperature and second cooling operation inlet pressure and reduce the temperature of the hydrogen to the storage tank storage temperature.

[0027] It should be noted that the cryogenic fluid boil-off mitigation system 100 (Figure 1) may be configured to receive hydrogen from both the previous cooling phase (e.g., the first cooling phase, additional cooling phase, cooling phase 110, represented by the first curve segment 212) and / or the boil-off hydrogen source that collects gaseous hydrogen from the storage tank for reliquefaction by the second cooling phase. Furthermore, support systems (e.g., pumps, valves, pressure regulators, temperature sensors, flow sensors, pressure sensors, etc.) may be associated with both the hydrogen received from the hydrogen source 104 and the hydrogen received from the boil-off hydrogen source so that the hydrogen received by the second cooling phase is at an appropriate pressure that allows cooling from the second cooling phase inflow temperature to the storage temperature of the storage tank via Joule-Thomson cooling technology. Furthermore, a second cooling operation may be configured to support passive cooling of a storage tank by receiving gaseous hydrogen, thereby generating a sufficient amount of boil-off to satisfy a boil-off threshold associated with temperature and / or pressure (for example, vaporization from liquid hydrogen to gaseous hydrogen in a tank removes the latent heat of vaporization from liquid hydrogen, effectively cooling the liquid in the storage tank). Thus, boil-off hydrogen (e.g., gaseous hydrogen produced by boil-off) may be collected by a pump or pipes that utilize the internal pressure of the tank to drive the gaseous hydrogen, and transferred to a second cooling operation which may be configured to remove the latent heat of vaporization and liquefy the boil-off hydrogen for introduction into the storage tank.

[0028] Figure 3 is a schematic diagram of a cryogenic fluid boil-off mitigation system 300 according to a further example of the present disclosure. The cryogenic fluid boil-off mitigation system 300 may include many of the features described above with reference to Figures 1 and 2. Specifically, the cryogenic fluid boil-off mitigation system 300 may include an intake mechanism 302 that receives hydrogen from a hydrogen source 304 and directs the hydrogen to a liquefaction system 306. The liquefaction system may include a plurality of cooling systems, including at least stages 1 308 and 2 310, that cool and liquefy the hydrogen before the liquid hydrogen is placed in a storage tank 312. Furthermore, the storage tank 312 may be monitored by a tank controller 314 via at least a temperature sensor 316 and a pressure sensor 318. Based on information received from at least the temperature sensor 316 and / or the pressure sensor 318, the tank controller 314 can determine when to cool the boil-off hydrogen in the storage tank and liquefy it by stage 2 312 of the cooling system. The tank controller 314 may be configured to have the boil-off collection system 320 collect boil-off hydrogen and transport it to stage 2 312, while the liquid hydrogen return system 322 can receive liquefied hydrogen from stage 2 312 and put the liquefied hydrogen into the storage tank 312.

[0029] The cryogenic fluid boil-off mitigation system 300 may utilize an intake mechanism 302 to regulate the hydrogen received from a hydrogen source 304, which does not regulate hydrogen. Specifically, the intake mechanism may include connector valves for pipes, hoses, and / or other connections to a hydrogen source controlled by an intake controller or by an operator associated with the cryogenic fluid boil-off mitigation system 300. The connector valves may include permanent connections to the hydrogen source 304 (e.g., for internal hydrogen sources such as hydrolysis or electrolysis systems, and for external vendors providing pipelines to the facility), and / or temporary connections to the hydrogen source 304 (e.g., the hydrogen source is a tank connected to the intake mechanism and delivered to the facility by truck and / or rails, which injects a certain amount of hydrogen). Regardless of the properties of the hydrogen source 304, the intake mechanism can regulate the inflow pressure (e.g., via the throttle valve), regulate the hydrogen flow rate, monitor the inflow pressure (e.g., via the pressure sensor), and monitor the inflow temperature (e.g., via the temperature sensor) through communication with various sensors associated with the intake mechanism 302 and signals transmitted to various components of the intake mechanism 302 (for example, signals can control the amount of pressure reduction caused by the throttle valve and / or the amount of pressurization caused by the pump). Thus, the inflow temperature, inflow pressure, inflow flow rate, and / or other physical properties of the hydrogen can be determined and transmitted to the liquefaction system 306.

[0030] As described above, stage 1 308 may be substantially similar and / or identical to cooling stage 1 110 described with respect to Figure 1. For example, stage 1 308 can cool the hydrogen below a threshold temperature using various periodic refrigeration techniques (e.g., inverse Carnot cycle, inverse Stirling engine, vapor compression cycle, heat exchange associated with the working fluid, etc.) and / or non-periodic refrigeration techniques (e.g., liquid nitrogen passing through a heat exchanger and then discharged into the atmosphere). Furthermore, the initial cooling of the incoming hydrogen by stage 1 308 received from the hydrogen source 304 can proceed according to the example shown in Figure 1, with reference to cooling stage 1 110. Furthermore, stage 2 310 may be substantially similar and / or identical to cooling stage 2 112 described with respect to Figure 1. For example, stage 2 310 can further cool and liquefy the hydrogen received from the hydrogen source 304 using Joule-Thomson cooling techniques (similar to the technique shown in Figure 1). Therefore, the hydrogen received from the hydrogen source 304 can be cooled, liquefied, and placed in the storage tank 312.

[0031] In some examples, the tank controller 314 may be configured to monitor at least the tank temperature and tank pressure associated with the storage tank 312. Specifically, the storage tank 312 may be a cryogenic storage tank containing cryogenic liquids in a cryogenic environment (e.g., below -50°C) and optionally in a pressurized environment (it should be noted that the storage of hydrogen and other flammable cryogenic fluids is generally under pressure to avoid leaks that would draw oxidizer into the storage tank / cryogenic fluid boil-off mitigation system 300). Thus, the storage tank 312 may be an insulated storage tank (such as a Dewar flask, which is a double-walled vessel with a high vacuum between the walls) which may include an internal cooling system (although these are generally neutralized by the additional heat energy transfer enabled by the internal cooling system), one or more sensors for monitoring the stored cryogenic fluid, and one or more connectors that allow the stored cryogenic fluid to be extracted from the storage tank 312 and put into the storage tank 312. In some additional examples, the storage tank 312 may include a fluid control device 320 (e.g., valves, openings, etc.) operably controlled by the tank controller 314. The fluid control device 320 may be connected to a boil-off processing loop indicated by flows A', B', C', A'', and B''. The fluid control device 320 may include any combination of valves and pumps to extract boil-off hydrogen from the storage tank 312, optionally pressurize the boil-off hydrogen (however, the internal pressure of the storage tank 312 may be sufficient to drive the boil-off hydrogen along flows A', B', C', A'', and / or B''), and achieve the described objective of providing boil-off hydrogen to the cooling system associated with stage 1 308 and / or stage 2 310. The first fluid control device may be positioned and configured to regulate the flow of boil-off hydrogen through flows A'' and B'', causing the liquefaction system 306 to process the boil-off hydrogen in a manner similar to that of hydrogen received from the hydrogen source 304. Alternatively, or additionally, a second and / or third fluid control device may be positioned and configured to regulate the flow of fluid through stage 2 310 and back into the storage tank 312.It should be understood that for each of the fluid control devices 320, there may be any number of valves and / or pumps to fully regulate the fluid flow, and the positions of the components may vary.

[0032] The hydrogen in the storage tank 312 can be a mixed-phase solution consisting of liquid hydrogen (the majority of the hydrogen in the storage tank 312) and a small amount of hydrogen in the gas phase. When the hydrogen is heated, the liquid hydrogen is converted from the liquid phase to the gas phase. The tank controller 314 may be configured to detect when the storage temperature and / or storage pressure of the hydrogen in the storage tank 312 meets (e.g., exceeds) a temperature threshold and / or a pressure threshold indicating that the boil-off hydrogen is to be processed and liquefied. Thus, the boil-off hydrogen (e.g., hydrogen in the gas phase) can be extracted from the storage tank 312 and directed to stage 2 310 of the liquefaction system 306, which can cool the boil-off hydrogen, remove the latent heat of vaporization from the gaseous hydrogen, convert the gas phase back to the liquid phase, and then return it to the storage tank 312. The overall temperature of the fluid in the storage tank 312 may be reduced accordingly, and the boil-off waste can be minimized or completely removed.

[0033] As described above, the tank controller 314 may be configured to monitor the storage temperature and storage pressure of hydrogen in the storage tank 312. Specifically, the tank controller may monitor the storage temperature via the temperature sensor 316 and the storage pressure via the pressure sensor 318. The tank controller 314 may be configured to monitor the storage temperature and storage pressure against one or more storage thresholds. These thresholds may be safety thresholds (e.g., the internal pressure and / or temperature of the storage tank 312 must remain below a threshold to prevent storage tank failure), efficiency thresholds (e.g., minimizing energy requirements to maintain the hydrogen level in the storage tank 312), and / or other thresholds determined by operational and / or business parameters. For example, a pressure threshold may be associated with a storage pressure that indicates a certain amount of hydrogen in the storage tank 312 has vaporized and the storage pressure is approaching the pressure limit of the storage tank 312 (this may include safety factors). Therefore, the tank controller 314 can detect when a pressure threshold is exceeded by the storage pressure and cause the fluid control device 320 to extract boil-off hydrogen (e.g., gaseous hydrogen) from the storage tank 312 via flow A', direct the boil-off hydrogen to the stage 2 310 cooling system via flow B', and return liquefied hydrogen to the storage tank 312 via flow C'. Furthermore, an additional pressure threshold may be associated with an additional storage pressure greater than the pressure threshold, indicating that additional boil-off mitigation will be performed. Therefore, the tank controller 314 can detect when an additional pressure threshold is exceeded and cause the fluid control device to extract boil-off hydrogen via flow A'', direct the boil-off hydrogen to the stage 1 308 cooling system via flow B'', and return liquefied hydrogen to the storage tank 312. The tank controller 314 may also be configured to operate the fluid control device 320 to manage the flow of boil-off hydrogen and may be connected to the fluid control device 320 via electron beam and / or wireless control. Furthermore, the tank controller 314 can communicate with the temperature sensor 316 and the pressure sensor 318 to receive storage tank data 322 via electron beam and / or wireless control.

[0034] The tank controller 314, temperature sensor 316, pressure sensor 318, and fluid control device 320 may be configured to work together to mitigate boil-off losses associated with the storage tank 312. If the two-phase mixture in the storage tank 312 is above a threshold temperature (e.g., a hydrogen inversion temperature of about 200K) and non-Joule-Thomson cooling is required at that point, the tank controller 314 can instruct the fluid control device 320 to move the boil-off hydrogen to the stage 1 boil-off loop 326, so that stage 1 308 of the liquefaction system 306 can cool the fluid using non-Joule-Thomson cooling, and then move the fluid to stage 2 310 for Joule-Thomson cooling, and finally return it to the storage tank 312. Alternatively, or additionally, the tank controller 314 may cause the fluid control device 320 to utilize the stage 1 boil-off loop 326 when the hydrogen storage pressure exceeds a threshold indicating the amount of cooling, thereby liquefying boil-off hydrogen that exceeds the cooling capacity of the stage 2 310 cooling system. Thus, by directing the boil-off hydrogen through both stage 1 308 and stage 2 310, and optionally through any additional cooling stage in the liquefaction system 306, the stage 1 boil-off loop 326 can be configured to cool boil-off hydrogen associated with a cooling amount that exceeds the hydrogen inversion temperature and / or exceeds the capacity of stage 2 310.

[0035] Furthermore, the tank controller 314, temperature sensor 316, pressure sensor 318, and fluid control device 320 may be configured to work together to mitigate boil-off losses associated with the storage tank 312. If the two-phase mixture in the storage tank 312 is below a threshold temperature (e.g., hydrogen inversion temperature at approximately 200K) and above a threshold pressure, the tank controller 314 can cause the fluid control device 320 to move the boil-off hydrogen into the stage 2 boil-off inlet 322 and return the liquid hydrogen to the storage tank 312 via the stage 2 boil-off outlet 324. Specifically, stage 2 310 of the liquefaction system 306 can cool the fluid using Joule-Thomson effect cooling and then return the liquid hydrogen to the storage tank 312. Alternatively, or additionally, the tank controller 314 can cause the fluid control device 320 to utilize the stage 2 boil-off inlet 322 for hydrogen storage temperatures that meet a threshold indicating the amount of cooling, and liquefy the boil-off hydrogen supplied by the cooling capacity of the stage 2 310 cooling system. Therefore, the boil-off inlet 322 of stage 2 may be configured to receive boil-off hydrogen that is below the hydrogen inversion temperature and / or associated with the amount of cooling that may be provided by stage 2 310.

[0036] In some examples, the Stage 2 boil-off inlet 322, the Stage 2 boil-off outlet 324, and / or the Stage 1 boil-off loop 326 may include a pump 328 (illustrated in relation to the Stage 1 boil-off loop 326) configured to change the fluid pressure from the discharge pressure of the storage tank 312 and / or Stage 2 310 to the inlet pressure of Stage 1 308, Stage 2 310, and / or the storage tank 312. Thus, rotary pumps, piston pumps, diaphragm pumps, screw pumps, centrifugal pumps, and other pumps can be used to change the fluid pressure based on the discharge pressure of one component and the inlet pressure of another component of the cryogenic fluid boil-off mitigation system 300.

[0037] After reaching the desired temperature, pressure, and phase, the hydrogen can enter the storage tank 312 by passing through the boil-off discharge 324 and / or the discharge of the liquefaction system 306 in stage 2. The storage tank 314 can hold the hydrogen until it is used to generate backup power, at which point the hydrogen can be moved out of the storage tank 312. In some examples, there may be tank outlet conduit hydrogen from the storage tank 312. In some additional examples, the tank controller 314 can extract hydrogen from the storage tank 314 and cause the fluid control device 322 to supply the hydrogen to the backup power system (e.g., backup power system 122).

[0038] In the examples of this disclosure, the liquefaction system 306 can be used to maintain hydrogen in the cryogenic fluid boil-off mitigation system 300 during long-term storage of hydrogen (e.g., for more than an hour, more than a day, more than a week, etc.). The cryogenic fluid boil-off mitigation system 300 can store some gaseous hydrogen via the Joule-Thomson cooling technique used in step 2 310, but may be configured to maintain hydrogen in the storage tank substantially as a liquid. The Joule-Thomson effect achieves cooling by allowing hydrogen to expand through a throttling device such as a valve or nozzle, which cools the hydrogen by dropping it from a source pressure (provided by a pump and / or storage tank) to a pressure determined under adiabatic conditions (e.g., an insulated throttling valve that is insulated to prevent heat transfer to or from the hydrogen). Thus, the tank controller 314 can manipulate process parameters (e.g., pressure, flow rate, etc.) via the flow control device 322 to achieve the desired cooling, return the hydrogen to the desired cryogenic temperature, and liquefy the gaseous hydrogen if necessary. In some examples, the Stage 2 310 cooling system may be configured to remove the latent heat of vaporization from the hydrogen by a tank controller 314 or other controller associated with the liquefaction system 306. In other examples, the Stage 2 310 cooling system may be configured to remove the latent heat of vaporization and additional heat from the hydrogen to achieve a desired temperature and / or pressure at which the hydrogen is introduced into the storage tank 312 via the Stage 2 boil-off discharge 324. In at least one embodiment, the latent heat of vaporization can account for more than 95% of the energy consumed by Stage 2 310 (e.g., the work required to generate the pressure necessary to cool and / or liquefy the hydrogen via the pump).

[0039] Figure 4 is a schematic diagram of a three-stage liquefaction system 400 according to a further example of the present disclosure. Note that the components shown in Figure 4 may be similar to and / or identical to the corresponding components described with reference to Figures 1 and 3. The liquefaction system 400 may include stage 1 402, stage 2 404, and stage 3 406. The liquefaction system 400 may include an intake mechanism 408 and an intake conduit 410 configured to receive and process hydrogen received from a hydrogen source (e.g., hydrogen source 104 and / or hydrogen source 304). The liquefaction system 400 may include conduits 412 configured to transport hydrogen to and / or from each of stage 1 402, stage 2 404, stage 3 406, and / or a storage tank (not shown). Fluid control devices 414a-e are arranged around the liquefaction system 400 and control the fluid movement between stages. Fluid control devices 414a-e may include any number of valves and / or pumps as needed to move fluid through the liquefaction system 400. Fluid control device 414a may be configured to control the intake conduit 410 and regulate the amount of hydrogen received by the liquefaction system from the hydrogen source. Fluid control devices 414b-d control the movement of fluid to and from stages 1 402, 2 404, and 3 406, respectively. Fluid control device 414e controls the movement of fluid from the liquefaction system 400 to a storage tank (not shown) or the like. The controller 416 may be associated with fluid control devices 414a-e and may be configured to generate signals to the fluid control devices 414a-e (for example, the fluid control devices are solenoid valves), to actuate the fluid control devices 414a-e (for example, the fluid control devices are air valves or hydraulic valves), and to actuate valves and / or pumps as needed to allow hydrogen to enter and exit the liquefaction system 400, and to actuate valves and / or pumps as needed between stages 1 402, 2 404, and 3 406. The conduit 412 may include a number of branches and associated valves that fluiduate the intake mechanism 408, stages 1 402, 2 404, 3 406, and a storage tank (not shown).Therefore, the conduit 412 may be configured to provide sufficient fluid pathways to selectively move hydrogen between the components of the liquefaction system 400 without unnecessarily impairing the flow or mixing the hydrogen from different components. Furthermore, although the conduit 412 is illustrated as being shared among all components, the conduit 412 can be divided into individual conduits that fluidly connect two components of the liquefaction system 400.

[0040] In some examples, the liquefaction system 400 may have any desired number of stages. The cryogenic systems herein can be used to process hydrogen, which has the somewhat inherent properties of a negative Joule-Thomson effect, as discussed above. Other cryogenic fluids have other properties that may require more stages, to which different processing principles can be applied to achieve efficient cooling and liquefaction. Thus, each stage can be a different processing mechanism. In other examples, the stages may be redundant, operating the same liquefaction mechanism on the fluid. Separating the liquefaction system 400 into a larger number of stages may allow for the achievement of higher efficiency. Thus, the liquefaction system 400 can be used in less than its full capacity. One application of using a portion of the liquefaction system 400 is to remove the latent heat of vaporization from boil-off hydrogen. The hydrogen can then be returned to a tank or directed to another location for use, which is achieved without requiring the entire liquefaction system 400.

[0041] Figure 5 is a block diagram of Method 500 according to an example of the present disclosure. Method 500 can be performed by one or more processors of a cryogenic fluid boil-off mitigation system, as illustrated and described above with respect to Figures 1-4. For example, any of the methods described herein with respect to Figures 5 and 6 may be performed, in whole or in part, by one or more processors of the tank controller 120 (Figure 1), tank controller 314 (Figure 3), controller 416 (Figure 4), and / or other control devices included in the cryogenic fluid boil-off mitigation system described herein. Unless otherwise stated, such processors are described in the remainder of the present disclosure without reference to the tank controllers 120, 314, controller 416, and / or other control devices described above.

[0042] In 502, the processor can manage the storage and maintenance of cryogenic fluids such as hydrogen in a desired low-temperature and stable environment, such as a storage tank. Specifically, the processor can receive temperature, pressure, and / or any other desired parameters from at least one or more sensors connected to the storage tank. Furthermore, one or more sensors can be connected to the storage tank so that the temperature, pressure, and / or other desired parameters are determined from at least the liquid phase and / or gas phase within the storage tank.

[0043] In 504, the processor may determine whether the boil-off hydrogen in the storage tank meets one or more pressure thresholds and / or one or more temperature thresholds. Furthermore, the processor may determine whether a boil-off mitigation action is desirable. Note that the desirability of a boil-off mitigation action may be based on one or more pressure thresholds, one or more temperature thresholds, a schedule, and / or in response to direct intervention by the operator. In 504, if the processor determines, at least based on the temperature and / or pressure of the storage tank, that the cryogenic fluid is within the operating thresholds of the storage tank (e.g., within the temperature and / or pressure range that defines a safe storage environment for a given amount of cryogenic fluid in the storage tank) (504-No), the processor may return to monitoring the cryogenic fluid in the storage tank in 502. The check in 504 may be performed any number of times if substantially desirable or according to a set schedule. For example, the check in 504 may be performed substantially continuously, periodically, and / or irregularly.

[0044] On the other hand, in step 504, if the processor determines, based on at least the temperature and / or pressure of the storage tank, that the cryogenic fluid exceeds the temperature and / or pressure thresholds associated with the storage tank (step 504 - yes), the processor may determine that the boil-off cryogenic fluid is to be extracted from the storage tank and reliquefied via the liquefaction system. Specifically, the temperature and / or pressure thresholds may be associated with the maximum safe storage pressure of the cryogenic fluid (optionally including a safety factor), the maximum safe storage temperature of the cryogenic fluid (optionally including an additional safety factor), a certain amount of boil-off cryogenic fluid stored in the tank, and / or other internal conditions of the storage tank that cause the processor to initiate a boil-off mitigation. As described above, the processor may monitor the temperature and / or pressure of the storage tank via one or more sensors connected to the storage tank and generate a display of the pressure and / or temperature inside the storage tank.

[0045] In 506, the processor may perform a second check to determine the cooling stage to be used during boil-off mitigation. As described above with respect to at least Figures 1, 3, and 4, the liquefaction system may include one, two, or more stages in a given example of the present disclosure. Thus, the processor may be configured to cause the liquefaction system to cool the cryogenic fluid received from the cryogenic fluid source and the boil-off cryogenic fluid extracted from the storage tank.

[0046] In 506, the processor may determine that the boil-off cryogenic fluid exceeds a temperature threshold and determine that step 1 is appropriate. Specifically, and as described above, some cryogenic fluids containing hydrogen have inversion temperatures below room temperature. Furthermore, a first cooling technique for a cryogenic fluid may be ineffective at temperatures above the temperature threshold but effective at additional temperatures below the temperature threshold. Alternatively, or additionally, a second cooling technique may be effective in cooling the cryogenic fluid at both temperatures above the temperature threshold and additional temperatures below the temperature threshold. Thus, step 1 may be associated with at least a second cooling technique that is effective at temperatures above the temperature threshold. Furthermore, in 506, the processor may determine that the boil-off cryogenic fluid satisfies a temperature threshold and determine that step 2 is appropriate. Step 2 may be associated with at least a first cooling technique that is effective at additional temperatures below the temperature threshold.

[0047] In 508, and if Stage 1 is appropriate (Step 506 – Stage 1), the processor may cause one or more fluid control devices to extract boil-off cryogenic fluid from a storage tank and to supply the boil-off cryogenic fluid to the Stage 1 cooling operation. Specifically, the processor may cause one or more pumps, valves, and / or other fluid control devices to extract boil-off cryogenic fluid from a storage tank and to supply the boil-off cryogenic fluid to the Stage 1 cooling operation via pipes, conduits, hoses, and / or other connections between the storage tank and the Stage 1 cooling operation. In some examples, pumps, valves, conduits, connections, and other fluid management components used to transport the boil-off cryogenic fluid between the storage tank and the Stage 1 cooling operation may be configured according to the consideration of the Stage 1 boil-off loop 326 illustrated by Figure 3. Furthermore, in 510, the processor may carry out Stage 1. Specifically, the processor may cause Stage 1 to reduce the boil-off hydrogen from a first temperature to a second temperature. Furthermore, the processor may be configured to adjust the amount of work used to cool the boil-off cryogenic fluid, adjust the amount of coolant / freezer used to cool the boil-off cryogenic fluid, and / or otherwise control the cooling operation in stage 1 to cool the boil-off cryogenic fluid from a first temperature to a second temperature. In some examples, stages 1 and 2 may be continuous, meaning that the fluid from stage 1 proceeds to stage 2. In other examples, the fluid may be directed to stage 1 and then discharged from the liquefaction system without reaching stage 2. In other examples, there may be a set of valves and controllers to direct the fluid from stage 1 to either stage 2 or back to the tank, as desired.

[0048] In step 512, the processor causes the fluid control device to provide the boil-off cryogenic fluid to step 2, and in step 514, the cooling operation in step 2 can reduce the cryogenic fluid from a second temperature to a third temperature, receiving the boil-off cryogenic fluid from step 1 (steps 506 to step 1), or reduce it from a first temperature to a third temperature, receiving the boil-off cryogenic fluid from the storage tank (steps 506 to step 2). In some examples, as discussed above, the boil-off cryogenic fluid may be directed to step 2 directly from the storage tank. Furthermore, the processor may cause the cooling operation in step 2 to cool the boil-off cryogenic fluid from a first temperature associated with the boil-off cryogenic fluid extracted from the storage tank to a third temperature associated with the temperature at which the boil-off cryogenic fluid can be placed in the storage tank. Furthermore, the processor may cause the cooling operation in step 2 to liquefy the boil-off cryogenic fluid so that the liquid cryogenic fluid can be placed in the storage tank. In some additional examples, the boil-off cryogenic fluid can be directed to stage 2 after the cooling operation of stage 1 is complete. Thus, the processor can have the cooling operation of stage 2 cool and optionally liquefy the boil-off cryogenic fluid received from stage 1 and put the boil-off cryogenic fluid into a storage tank. After the cooling operation of stage 2 is complete, the processor can have the fluid control unit return the boil-off cryogenic fluid, which is now a liquid cryogenic fluid, to the storage tank and continue monitoring the storage tank and the cryogenic fluid in 502. If there are other stages in the system, they can be considered in an appropriate order. The stages may be continuous to provide greater control over the cooling of the boil-off cryogenic fluid (e.g., allowing the cooling stages to cool over a lower temperature range), parallel to provide greater capacity control (e.g., parallel cooling operations may have the minimum flow requirements, thus allowing the cooling stages to have greater control throughput), and / or any combination of continuous and parallel cooling stages.

[0049] Therefore, the method shown in Figure 5 makes it possible to reduce boil-off losses for cryogenic fluids stored by cryogenic fluid boil-off mitigation systems as described in Figures 1-4. Specifically, by continuously detecting the internal temperature and pressure of the storage tank, the processor of the cryogenic fluid boil-off mitigation system can track the amount of boil-off cryogenic fluid generated and the amount of incident heat transferred between the atmosphere and the cryogenic fluid. Furthermore, by detecting the internal temperature and pressure, safety features can be implemented to ensure the continuous flow of cryogenic fluid without incident. Thus, the processor can extract, liquefy, and reintroduce cryogenic fluid from the storage tank that would otherwise be discharged into the atmosphere and lost for safety and maintenance reasons. In addition, the periodic extraction, liquefaction, and reintroduction of boil-off cryogenic fluid enables long-term storage of cryogenic fluid and reduces the amount of cryogenic fluid introduced into the storage tank from an external source.

[0050] Figure 6 is a block diagram of Method 600 according to a further example of the present disclosure, in which a single step is used for the purpose of boil-off. Method 600 can be performed by one or more processors of a cryogenic fluid boil-off mitigation system, as illustrated and described above with respect to Figures 1-4. The cryogenic fluid boil-off mitigation system of the present disclosure may include a liquefaction system controlled by one or more processors. The liquefaction system may also include a dedicated boil-off control step, shown above as step 2. Naturally, the boil-off control step may not be step 2 of the process. In 602, the processor can receive a cryogenic fluid, such as hydrogen, from a cryogenic fluid source, cool it by the liquefaction system, and then store it in a storage tank. The cryogenic fluid may be a mixed-phase solution in the storage tank, present in both liquid and gas phases. Furthermore, the processor can monitor the internal temperature and internal pressure of the storage tank via one or more sensors (e.g., temperature sensors, pressure sensors, etc.). Thus, the process can store the cryogenic fluid and monitor the cryogenic fluid in the storage tank.

[0051] In step 604, the processor can determine whether a boil-off mitigation action is desirable. For example, as part of this determination, the processor may determine whether boil-off hydrogen in the storage tank meets one or more pressure thresholds and / or one or more temperature thresholds. Note that the desirability of a boil-off mitigation action determined in step 604 may be determined based on one or more pressure thresholds, one or more temperature thresholds, a schedule, and / or in response to direct intervention by the operator.

[0052] In step 604, if the processor determines, based at least on the temperature and / or pressure of the storage tank (stored in 602), that the cryogenic fluid is within the operating thresholds of the storage tank (e.g., within the temperature and / or pressure range that defines a safe storage environment for a given amount of cryogenic fluid in the storage tank) (step 604 – No), then in step 602, the processor can return to monitoring the cryogenic fluid in the storage tank. The check in 604 can be performed any number of times if substantially desirable or according to a set schedule. For example, the check in 604 can be performed substantially continuously, periodically, and / or irregularly.

[0053] On the other hand, in 604, if the processor determines, based on at least the temperature and / or pressure of the storage tank (stored in 602), that the cryogenic fluid exceeds the temperature threshold and / or pressure threshold associated with the storage tank (step 604 - yes), the processor may determine that the boil-off cryogenic fluid is to be extracted from the storage tank and reliquefied via the liquefaction system. Specifically, the temperature threshold and / or pressure threshold may be associated with the maximum safe storage pressure of the cryogenic fluid (optionally including a safety factor), the maximum safe storage temperature of the cryogenic fluid (optionally including an additional safety factor), a certain amount of boil-off cryogenic fluid stored in the tank, the inversion temperature of the cryogenic fluid, and / or other internal conditions of the storage tank that cause the processor to initiate boil-off mitigation. In at least one embodiment, extracting the cryogenic fluid from the storage tank at a temperature higher than the inversion temperature may represent a safety issue due to a pressure drop caused by the extraction of the boil-off cryogenic fluid, which would heat the remaining cryogenic fluid in the storage tank. Therefore, the temperature threshold may be selected or determined to be below the inversion temperature at which boil-off cryogenic fluid is extracted from the storage tank, and the extraction of boil-off cryogenic fluid cools the stored cryogenic fluid. As described above, the processor can monitor the temperature and / or pressure of the storage tank via one or more sensors connected to the storage tank and generate a display of the pressure and / or temperature inside the storage tank.

[0054] In 606, the processor may extract cryogenic fluid from the storage tank and provide it to step 2 by one or more fluid control devices. Specifically, the processor may be configured to operate a valve (e.g., fluid control device 320) (e.g., via an electronic signal, an air pump, a hydraulic pump, etc.) to open a fluid connection between the storage tank and the cooling operation in step 2. Furthermore, the processor may be configured to use the internal pressure of the pump and / or storage tank to transport the boil-off cryogenic fluid from the storage tank to the cooling operation in step 2.

[0055] In 608, the processor can determine the amount of cooling provided by the cooling operation in stage 2. Specifically, the processor can cause the cooling operation in stage 2 to cool the cryogenic fluid from a first temperature to a second temperature, and optionally liquefy the cryogenic fluid. Furthermore, the processor can cause one or more fluid control devices associated with stage 2 to return the cryogenic fluid to the tank, or otherwise discharge the cryogenic fluid from stage 2 at appropriate pressure and temperature. Notably, stage 608 can be performed in a manner similar to stage 514, such that the processor causes the cooling operation in stage 2 (e.g., Joule-Thomson cooling) to cool the boil-off cryogenic fluid from a first temperature to a second temperature, liquefy the boil-off cryogenic fluid, and return the liquid cryogenic fluid to the storage tank. Similar to extraction from the storage tank, the processor can cause one or more fluid control devices (e.g., operating one or more valves and one or more pumps) to transport the liquid cryogenic fluid between the discharge in stage 2 and the inflow into the storage tank.

[0056] Therefore, the method shown in Figure 6 makes it possible to reduce boil-off losses for cryogenic fluids stored by cryogenic fluid boil-off mitigation systems as described in Figures 1-4. Specifically, hydrogen and other cryogenic fluids can be associated with inversion temperatures that fall within the operating range of the liquefaction system used to liquefy the inflowing hydrogen from the hydrogen source for storage in the storage tank. Furthermore, the inversion temperature can represent an operating range in which the Joule-Thomson cooling technique does not cool the hydrogen but instead heats it. If not properly managed, extracting hydrogen from the storage tank while the hydrogen is heated by the pressure drop can trigger a potentially dangerous cycle in which the stored hydrogen is heated by the extraction of boil-off hydrogen. Therefore, the processor associated with the cryogenic fluid boil-off mitigation system may be configured to cool boil-off hydrogen to prevent the stored hydrogen or cryogenic fluid from exceeding the inversion temperature and to ensure the safe storage and maintenance of the stored hydrogen. [Industrial applicability]

[0057] In large-scale facilities such as data centers, backup power can be provided by hydrogen-powered engines (or fuel cells) that consume hydrogen as fuel to power the facility. Compared to diesel generator sets commonly used as backup power, hydrogen-powered engines (or fuel cells) can provide lower carbon emissions, cleaner emergency power, and an alternative fuel source. Because liquid hydrogen must be stored at extremely low temperatures, hydrogen storage may involve precise control schemes and maintenance of storage tanks (e.g., storage temperature and pressure). The systems and methods of this disclosure provide liquefaction systems and boil-off loops that can be used to recover boil-off hydrogen that would otherwise be discharged into the atmosphere. For example, the systems described herein include a Joule-Thomson cooling stage that enables relatively low-power maintenance of stored liquid hydrogen and relatively low-power reuse of boil-off hydrogen that would otherwise be lost. The low-power cooling stage (e.g., Joule-Thomson cooling stage) can be maintained in continuity with other more power-intensive cooling systems, but also provides an alternative inflow that allows for cooling of boil-off hydrogen if necessary.

[0058] As a result of the technologies described herein, various systems of this disclosure can mitigate or prevent hydrogen loss due to the natural heating of a storage tank. Natural heating of a storage tank evaporates the stored liquid hydrogen into gaseous hydrogen, which increases the internal pressure and temperature of the storage tank. Instead of discharging the gaseous hydrogen (which would necessitate the periodic purchase or generation of hydrogen), the boil-off hydrogen can be collected and processed by a component of a liquefaction unit. By passing the hydrogen through a relatively low-energy cooling system (e.g., a Joule-Thomson cooling system), the hydrogen can be liquefied and reintroduced into the storage tank. Thus, the systems described can reduce the amount of hydrogen obtained from an external source, the amount of hydrogen produced by an internal source, or the amount of hydrogen otherwise introduced into the backup power system. Furthermore, the systems described can be configured to maintain the internal temperature and pressure of the storage tank within safety parameters. As a result, the disclosed systems can maintain a backup power supply without incurring the relatively high component costs, complexity, contamination, and frequent maintenance downtime associated with known systems.

[0059] While aspects of this disclosure have been specifically shown and described with reference to the embodiments described above, it will be understood by those skilled in the art that various additional embodiments may be conceived by modifications of the disclosed machines, systems, and methods without departing from the spirit and scope of the disclosed content. Such embodiments should be understood to fall within the scope of this disclosure as determined by the claims and any equivalents thereof.

Claims

1. It is a system, A storage tank configured to store cryogenic hydrogen in a two-phase mixture, A liquefaction system configured to receive hydrogen from an external source, wherein the liquefaction system includes a Joule-Thomson cooling step and a non-Joule-Thomson cooling step fluidly connected to the Joule-Thomson cooling step, and the liquefaction system is The hydrogen is received in the non-Joule-Thomson cooling stage. In the non-Joule-Thomson cooling step, the hydrogen is cooled to a first temperature below a temperature threshold. At the first temperature, the hydrogen is transferred from the non-Joule-Thomson cooling step to the Joule-Thomson cooling step. In the Joule-Thomson cooling step, the hydrogen is cooled to a second temperature lower than the first temperature. A liquefaction system further configured to transfer the hydrogen from the Joule-Thomson cooling stage to the storage tank at the second temperature, A boil-off loop configured to transfer boil-off hydrogen from the storage tank to the Joule-Thomson cooling stage of the liquefaction system, Equipped with, The Joule-Thomson cooling step is configured to cool the boil-off hydrogen to a third temperature and transfer the cooled boil-off hydrogen to the storage tank at the third temperature. The boil-off loop is configured to raise the pressure of the boil-off hydrogen to a first pressure that exceeds a pressure threshold associated with the Joule-Thomson cooling step. system.

2. The system further comprises a controller operably connected to one or more fluid control devices, wherein the controller At least one of the temperature sensor and pressure sensor associated with the storage tank receives at least one of the temperature of the hydrogen contained in the storage tank and the pressure of the hydrogen contained in the storage tank. Determine at least one of the temperature of the hydrogen placed in the storage tank that exceeds a temperature threshold, and the pressure of the hydrogen placed in the storage tank that exceeds a pressure threshold. Based on at least the above determination, one or more fluid control devices are configured to transfer the boil-off hydrogen to the boil-off loop, The system according to claim 1.

3. A flow control device fluid-connected to the boil-off loop directs the boil-off hydrogen to the non-Joule-Thomson cooling stage. The non-Joule-Thomson cooling step further includes a controller configured to direct the boil-off hydrogen to the Joule-Thomson cooling step via a fluid passage extending from the non-Joule-Thomson cooling step to the Joule-Thomson cooling step. The system according to claim 1.

4. The Joule-Thomson cooling step is configured to remove the latent heat of vaporization from the boil-off hydrogen and return the liquefied hydrogen to the storage tank. The system according to claim 1.

Images