Electrical control and / or monitoring for a cryogenic storage vessel

Abstract

An electrical control and / or monitoring system for use with a cryogenic storage vessel has an electrical component, an enclosure surrounding the electrical component, an inert volume within the enclosure between the electrical component and the enclosure, and a control system. The control system has one or more pressure sensors configured to measure the pressure of the inert volume, and one or more pressure sensors configured to measure the pressure of a cryogen and / or cryogenic liquid within the cryogenic storage vessel. The control system is configured to regulate the electrical component based on pressure data from the one or more pressure sensors configured to measure the pressure of the inert volume, and the one or more pressure sensors configured to measure the pressure of a cryogen and / or cryogenic liquid within the cryogenic storage vessel.

Description

[0001] ELECTRICAL CONTROL AND / OR MONITORING FOR A CRYOGENIC STORAGE VESSEL

[0002] FIELD OF THE INVENTION

[0003] The present invention relates to an electrical control and / or monitoring for a cryogenic storage vessel.

[0004] BACKGROUND OF THE INVENTION

[0005] Cryogenic systems are used for producing, maintaining and storing cryogenic liquids or cryogens, which are liquefied gases, and other substances at very low temperatures. Cryogens are produced by liquefying gases by cooling them until they change state to liquid. Cryogenic systems are now widely used in a number of different industries as they have proven to be useful in many different processes.

[0006] Cryogenic systems typically have cryogenic liquid storage systems comprising a storage vessel for the cryogenic liquid. A product of cryogenic systems is boil-off gas, which are vapourised gases from the stored cryogenic liquid in the storage vessel. Boil-off gas is produced in a cryogenic storage vessel due to natural evaporation of the cryogenic liquid as some heat is inevitably transferred to the cryogenic liquid.

[0007] Cryogenic storage often requires electrical control and monitoring. For example, cryogenic storage vessels often require controlled heat addition for the evaporation and pressurisation of the cryogenic gas at a rate to match the intended application of the cryogenic gas. In another example, cryogenic storage vessels often require other electrical components, such as one or more pressure sensors, temperature sensors, sensors to determine the level of liquid in the storage vessel. The sensors may have associated wires or other electrical components.

[0008] Cryogenic gases may be flammable, combustible or oxidising. Accordingly, in situations in which the cryogenic gases is flammable or combustible, any ignition source must be kept out of contact with such cryogenic gases and / or liquids. It will be understood that a heat source may be an ignition source. Other electrical components, such as sensors, may also be an ignition source. As a result, it is difficult to provide a heat source for the cryogenic gases and / or liquids that efficiently and safely transfers heat to the cryogenic gases and / or liquids.

[0009] It is also difficult to control and monitor the cryogenic gases and / or liquids in a safe manner.

[0010] In addition, in situations in which the cryogenic gases are oxidising, any combustible source must be kept out of contact with such cryogenic gases and / or liquids.

[0011] In this specification, where reference has been made to external sources of information, including patent specifications and other documents, this is generally for the purpose of providing a context for discussing the features of the present invention. Unless stated otherwise, reference to such sources of information is not to be construed, in any jurisdiction, as an admission that such sources of information are prior art or form part of the common general knowledge in the art.

[0012] For the purpose of this specification, where method steps are described in sequence, the sequence does not necessarily mean that the steps are to be chronologically ordered in that sequence, unless there is no other logical manner of interpreting the sequence.

[0013] It is an object of the present invention to provide an electrical control and / or monitoring system for a cryogenic storage vessel; and / or a method for controlling and / or monitoring cryogenic liquids and / or cryogens in a cryogenic storage vessel; which overcomes or at least partially ameliorates some of the abovementioned disadvantages, or which at least provides the public with a useful choice.

[0014] BRIEF DESCRIPTION OF THE INVENTION

[0015] According to a first aspect of the invention, there is provided an electrical control and / or monitoring system for use with a cryogenic storage vessel comprising: an electrical component; an enclosure surrounding the electrical component; an inert volume within the enclosure between the electrical component and the enclosure; a control system comprising one or more pressure sensors configured to measure the pressure of the inert volume, and one or more pressure sensors configured to measure the pressure of a cryogen and / or cryogenic liquid within the cryogenic storage vessel, the control system configured to regulate the electrical component based on pressure data from the one or more pressure sensors configured to measure the pressure of the inert volume, and the one or more pressure sensors configured to measure the pressure of a cryogen and / or cryogenic liquid within the cryogenic storage vessel.

[0016] In some configurations, the inert volume comprises an inert gas.

[0017] In some configurations, the inert volume is an inert gas.

[0018] In some configurations, the electrical control and / or monitoring system further comprises a power source for providing power to the electrical component.

[0019] In some configurations, the electrical control and / or monitoring system further comprises electrical wires electrically connecting the power source to the electrical component.

[0020] In some configurations, the enclosure comprises a conduit surrounding at least part of the length of the electrical wires.

[0021] In some configurations, the enclosure comprises a conduit surrounding a major part of the length of the electrical wires.

[0022] In some configurations, the enclosure comprises a conduit surrounding the entire length of the electrical wires.

[0023] In some configurations, the enclosure comprises a reservoir providing an additional inert volume.

[0024] In some configurations, the electrical control and / or monitoring system further comprises one or more temperature sensors configured to measure the temperature of the inert volume. In some configurations, the electrical control and / or monitoring system further comprises one or more temperature sensors configured to measure the temperature of a cryogen and / or cryogenic liquid within the cryogenic storage vessel.

[0025] In some configurations, the inert gas is helium gas.

[0026] In some configurations, the inert gas is neon gas, argon gas, krypton gas, or nitrogen gas.

[0027] In some configurations, the inert gas is a combination of two or more of neon gas, argon gas, krypton gas, or nitrogen gas.

[0028] According to a second aspect of the invention, there is provided a cryogenic system comprising: the electrical control and / or monitoring system of the first aspect; a cryogenic storage vessel comprising: an inner wall defining a containment volume within the inner wall for containing the cryogenic fluids; an outer wall defining an external periphery of the cryogenic storage vessel; the inner wall spaced inwardly from the outer wall; and an insulation volume between the outer wall and inner wall wherein the inert volume within the enclosure has a pressure and the cryogenic gas within the cryogenic storage vessel has a pressure, the pressure of the inert volume within the enclosure being greater than the pressure of the cryogenic gas within the cryogenic storage vessel.

[0029] In some configurations, the cryogenic storage vessel contains cryogenic liquid and cryogenic gas.

[0030] In some configurations, the inert gas has a pressure of about 100kPa to about 3000kPa.

[0031] In some configurations, the cryogenic gas has a pressure of about 10kPa to about WOOkPa. In some configurations, the cryogenic fluid in the storage vessel is hydrogen.

[0032] In some configurations, the cryogenic fluid in the storage vessel is oxygen.

[0033] In some configurations, the cryogenic fluid in the storage vessel is natural gas.

[0034] In some configurations, the cryogenic system further comprises a hazardous zone, the hazardous zone being an area that contains the cryogenic storage vessel; and a non- hazardous zone, the non-hazardous zone being a location in which the levels of the cryogens are not flammable or where the cryogens do not exist, the non-hazardous zone being separated from the hazardous zone by distance and / or a physical barrier.

[0035] In some configurations, the control system comprises a control interface located in the non- hazardous zone NHZ.

[0036] In some configurations, the control system comprises a power source located in the non- hazardous zone.

[0037] Other aspects of the invention may become apparent from the following description which is given by way of example only and with reference to the accompanying drawing.

[0038] As used herein the term 'and / or' means 'and' or 'or', or both.

[0039] As used herein, '(s)' following a noun means the plural and / or singular forms of the noun.

[0040] As used herein, the term 'inert gas' means a gas that does not form chemical reactions with other chemical substances and therefore does not form chemical compounds. The term includes the elements in group 18 of the periodic table, such as helium (He), neon (Ne), and argon (Ar). The term also includes nitrogen (N) because it shares the same low reactivity and reluctance to form compounds that the elements in group 18 of the periodic table do. As used herein, the term 'inert atmosphere' means an atmosphere that is free of chemical substances that react to form chemical reactions with other chemical substances and therefore do not form chemical compounds. The term includes atmospheres that are free from oxygen (O) and carbon dioxide (CO2).

[0041] The term 'comprising' as used in this specification and claims means 'consisting at least in part of'. When interpreting statements in this specification and claims which include that term, the features, prefaced by that term in each statement, all need to be present but other features can also be present. Related terms such as 'comprise' and 'comprised' are to be interpreted in the same manner.

[0042] BRIEF DESCRIPTION OF THE DRAWING

[0043] The invention will now be described by way of example only and with reference to the drawing in which:

[0044] Figure 1 shows a schematic drawing of a cryogenic storage vessel and an electrical control and / or monitoring system for the cryogenic storage vessel.

[0045] DETAILED DESCRIPTION

[0046] According to various aspects of the present invention as illustrated in figure 1, there is provided a cryogenic storage vessel 10 and an electrical control and / or monitoring system 100 for the cryogenic storage vessel 10. It will be appreciated that this figure illustrates the general principles of the structure and construction, and that the invention is not limited to the precise configuration illustrated.

[0047] Figure 1 shows a hazardous zone HZ and a non-hazardous zone NHZ. The hazardous zone is an area that contains the cryogenic storage vessel 10. The hazardous zone outside the cryogenic storage vessel 10 may have a level of cryogens that could be flammable. The non- hazardous zone is a location in which the levels of the cryogens are not flammable or where the cryogens do not exist. The non-hazardous zone may be separated from the hazardous zone by distance and / or a physical barrier.

[0048] Application of cryogenic storage for a flammable gas often requires controlled heat addition for the evaporation and pressurisation of that gas at a rate to match the intended application. A convenient and practical means of heating such a cryogenic fluid is to insert an electrically powered heating device. Such a device must have suitable isolation from the cryogenic fluid and cryogens so that it does not present as an ignition source in a potentially flammable atmosphere either inside or outside the storage vessel.

[0049] Other electrical components, such as sensors, may also be an ignition source. Those other electrical components must also be suitably rated or have suitable isolation from the cryogenic fluid and cryogens so that it does not present as an ignition source in a potentially flammable atmosphere either inside or outside the storage vessel 10.

[0050] Cryogenic gases may be flammable, combustible or oxidising. Accordingly, in situations in which the cryogenic gases is flammable or combustible, any ignition source must be kept out of contact with such cryogenic gases and / or liquids. It will be understood that an electrical component, such as a heat source or a sensor, may be an ignition source.

[0051] In addition, in situations in which the cryogenic gases is oxidising, such as oxygen, any combustible source or ignition source must be kept out of contact with such cryogenic gases and / or liquids.

[0052] The electrical control and / or monitoring system 100 has one or more electrical components. Figure 1 shows that one of the electrical components is an electrically powered heat source 2. The heat source 2 is a block with one or more electrically powered heating elements 4. The block also has one or more sensors and / or switches 6. In some configurations, the heat source and / or heating elements have electrical insulation built in to provide another layer of separation from the cryogenic gases and / or liquids.

[0053] In some configurations, the system 100 also has a power source 12 for providing power to the heat source. The power source 12 is located externally from the cryogenic storage vessel 10 in the non-hazardous zone NHZ. Figure 1 shows the system also has electrical wires 14 electrically connecting the power source 12 to the heat source 2. The system 100 also has electrical wires 14 for other electrical components. Figure 1 shows the system 100 has electrical wires 14 for sensors, the sensors are described in more detail below.

[0054] The electrical wires 14 extend from the heat source 2 and / or sensors in the cryogenic storage vessel 10 through to the non-hazardous zone NHZ.

[0055] The heating element(s) is / are regulated by a control system. The control system has a control interface 16 that is located in the non-hazardous zone NHZ. Figure 1 shows that the control interface 16 and the power source 12 are in the same unit and / or housing. Alternatively, they may be in separate units or housings.

[0056] The control system comprises sensors 18, 42, which may be pressure sensors and / or temperature sensors. The sensors 18, 14 are mounted to or within the volume that includes enclosure 34 and conduit 36 and reservoir 38. The enclosure 34 and conduit 36 and reservoir 38 are described in more detail below.

[0057] The pressures sensors may be located anywhere in the enclosed system (either the enclosure 34 and / or the conduit 36 and / or the reservoir 38). For example, in configurations in which the inert atmosphere is helium, the helium will be gaseous and will be the same pressure, or very small difference in pressure, throughout the enclosure 34 and / or the conduit 36 and / or the reservoir 38. As describe herein, there are two pressure sensors 42 for redundancy adjacent to the control interface 16. In use, these sensors will detect the pressure of the conduit 36.

[0058] The pressure readings will be monitored to ensure the pressure of the gas in the conduit 36 is a higher pressure than the vessel pressure at all times to ensure that any possible leak in the system will leak in the safe direction (from inert space to the potentially flammable space in the storage vessel 10).

[0059] Figure 1 shows the system has one or more temperature sensors 18 configured to measure the temperature of an inert volume within the conduit. (The features of the inert volume are described in more detail below). There is at least one temperature sensor 18 located in the conduit 36 and / or enclosure to measure the temperature of the inert atmosphere in the conduit 36 and / or enclosure 34 that is located in a portion of the cryogenic storage vessel 10 that contains the cryogens. There is at least one temperature sensor 18 located in the conduit 36 and / or enclosure 34 to measure the temperature of the inert atmosphere in the conduit 36 and / or enclosure 34 that is located in a portion of the cryogenic storage vessel 10 that contains the cryogenic liquid. In addition to measuring the temperature of the conduit 36 and / or enclosure 34 in different locations in the cryogenic storage vessel 10, the two sensors 42 provide redundancy. The control system uses data from these sensors to determine whether to supply or stop electricity supply to the heat source 2 to heat the cryogenic liquid.

[0060] It will be appreciated that the temperature sensors (or sensors measuring some other property) may be mounted in a variety of different locations. For example, in some configurations, there may be temperature sensors and temperature switches inside the enclosure 34 only. In other configurations, it may be advantageous to have temperature sensors elsewhere in the conduit 36.

[0061] The inert volume provides a contained inert atmosphere. The inert atmosphere is created by an inert gas. In some configurations, the inert gas is helium gas. The inert gas may consist essentially of helium. In alternative configurations, the inert gas may be neon gas, argon gas, krypton gas or nitrogen gas. The inert atmosphere may be provided by any of those gases alone or in combination.

[0062] Although the inert gas may be any one of, or a combination of two or more of, the elements in group 18 of the periodic table, or nitrogen, the gas chosen will depend on a variety of different factors. Such as whether the inert gas is readily available, the cost of the inert gas, or the intended cryogenic liquid, and the expected temperature of the cryogenic liquid and / or cryogen. Each of the cryogen and the inert gas will change phases at their boiling point. Accordingly, the inert gas will be selected to be a gas that has a phase change at a lower boiling point than the boiling point of the cryogen. That ensures the inert gas remains as a gas and does not condense, or at least will have minimal condensation.

[0063] The enclosure 34 is a non-permeable material such that neither the inert gas nor the cryogen will be able to pass through the wall(s) of the enclosure 34. The enclosure 34 may be insulated. In addition, there is a pressure difference between the inert gas and the cryogen, described in more detail below, which also acts to ensure that if there is any fluid transfer, it is the inert gas that transfers into the vessel and not the cryogen entering the inert volume.

[0064] The enclosure 34 extends beyond the tank in a conduit or pipe 36. The electrical wires 14 and optionally sensors 18, 42 are located inside the conduit 36. This conduit 36 extends away from the liquid storage vessel 10 to a location where the electrical wires 14 can exit into the non-hazardous zone NHZ. That is, in the embodiment shown, the enclosure not only surrounds the electrical component, and isolates the electrical component from the cryogenic gas within the cryogenic storage vessel, it also continues to isolate the electrical component until it reaches the non-hazardous zone NHZ.

[0065] Figure 1 shows the conduit 36 surrounding a major part of the length of the electrical wires 14. In alternative configurations, the enclosure comprises a conduit surrounding at least part of the length of the electrical wires. In other alternative configurations, the enclosure comprises a conduit surrounding the entire length of the electrical wires. Figure 1 shows the conduit 36 surrounds at least the portion of the electrical wires 14 that is within the cryogenic storage vessel 10, and optionally a portion of the wires that is external to the cryogenic storage vessel 10.

[0066] In addition to surrounding the block 2, due to the conduit 36, it will be understood that the inert volume extends from within the cryogenic storage vessel 10 to outside the cryogenic storage vessel 10. Figure 1 shows the inert volume extends for a distance from the vessel until it reaches the non-hazardous zone. The distance depends on the gas and the specific installation. In use, the hazardous area will be assessed to define the extent of a hazardous area. It may be several metres, such as 3 metres, 5 metres, or over 10 metres. In the non- hazardous zone, the electrical connections can safely be terminated into the power supply 12 and control interfaces 16.

[0067] There is provision to re-charge the inert gas within the enclosure 34 and conduit 36. In particular, there is a reservoir 38 that provides additional warm volume attached to the enclosure 34 and conduit 36 so that the pressure of the inert gas in the system maintains a safe margin above the cryogen pressure when cooled down from warm. The inert atmosphere is at a pressure that exceeds the maximum pressure in the storage vessel 10 by a safe margin, such that any leak would be from the enclosure 34 and / or conduit 36 into the containment volume 28 (not the reverse direction, which may be hazardous).

[0068] The inert atmosphere may have a pressure of about 100kPa to about 3000kPa. The inert atmosphere may have a pressure of about 200kPa, about 300kPa, about 400kPa, about 500kPa, about 600kPa, about 700kPa, about 800kPa, about 900kPa, about 1000kPa, about 1100kPa, about 1200kPa, about 1300kPa, about 1400kPa, about 1500kPa, about 1600kPa, about 1700kPa, about 1800kPa, about 1900kPa, about 2000kPa, about 2100kPa, about 2200kPa, about 2300kPa, about 2400kPa, about 2500kPa, about 2600kPa, about 2700kPa, about 2800kPa, or about 2900kPa.

[0069] The pressure range of the inert gas is chosen such that there is a safe margin above the pressure of the cryogen. Additionally, there is advantage if the inert gas can be held at significantly higher pressure so that it can be charged to high pressure, which then diminishes as the vessel is filled with cryogen. As the cold region of the inert gas containment cools, the pressure drops. So if the pressure is a high pressure at the beginning, the pressure will remain higher than the cryogen vessel pressure after cool down, without having to top up the inert gas space.

[0070] The safety margin may be about 90kPa, about 100 kPa, about 200kPa, about 300kPa, about 400kPa, about 500kPa, about 600kPa, about 700kPa, about 800kPa, about 900kPa, about 1000kPa, about 1100kPa, about 1200kPa, about 1300kPa, about 1400kPa, about 1500kPa, about 1600kPa, about 1700kPa, about 1800kPa, about 1900kPa, or about 2000kPa.

[0071] The enclosure 34 together with the inert volume within the enclosure provide separation of the electrical heating element(s), control(s) of the electrical control and / or monitoring system, and other potential ignition sources, from the cryogens and cryogenic liquid.

[0072] The cryogenic storage vessel 10 may generally comprise of an outer wall 20 defining an external periphery of the cryogenic storage vessel 10. The cryogenic storage vessel 10 may generally comprise of an inner wall 24 defining a containment volume 28 within the inner wall for containing the cryogenic fluids. The containment volume 28 generally serves to contain the cryogenic liquids 8 and associated vapours 9, and also serves to constrain, control and / or define in part the associated temperatures, pressures and other properties imparted onto the cryogenic storage vessel by the cryogenic liquids, once received thereby.

[0073] The inner wall 24 in some configurations is spaced inwardly from the outer wall 20. The cryogenic storage vessel 10 has an insulation volume between the outer wall and inner wall.

[0074] The insulation volume generally acts to insulate the contents of the cryogenic storage vessel 10 from the environment and associated temperatures external the cryogenic storage vessel 10. In other configurations, a solid insulation may be applied to the external periphery of the cryogenic storage vessel 10.

[0075] In the cryogenic storage vessel 10 typically a portion of the cryogenic fluid stored in the vessel is in liquid form. However, a portion of the fluid will be gas (i.e. boil-off gas). Boil-off gas may be particularly prevalent at early stages of a cryogenic process as cryogenic liquid contacting the inner wall of the storage may undergo rapid temperature change. The cryogenic liquid will boil-off or vaporise from its liquefied state upon contact with the inner wall. Alternatively, or additionally boil-off or vaporisation of the cryogenic fluid occurs naturally due to evaporation of the cryogenic fluid stored in the vessel 10.

[0076] In some configurations, the cryogenic storage vessel 10 has a fill port (not shown) defining a passageway for cryogenic liquid to enter the containment volume 28. The cryogenic storage vessel 10 also has an exit port (not shown) defining a passageway for cryogenic gas to be provided to another vessel or container, or directly to its intended use.

[0077] In some configurations, the inert gas has a pressure and the cryogenic gas within the cryogenic storage vessel 10 has a pressure, the pressure of the inert gas being greater than the pressure of the cryogenic gas within the cryogenic storage vessel 10. The cryogen may have a pressure within the cryogenic storage vessel of about 50kPa to about 1000kPa. The cryogen may have a pressure of about 100kPa, about 200kPa, about 300kPa, about 400kPa, about 500kPa, about 600kPa, about 700kPa, about 800kPa, or about 900kPa.

[0078] The cryogenic fluid stored in the vessel may be hydrogen, oxygen, or natural gas. For example, the electrical control and / or monitoring system may be particularly useful for processing hydrogen or any other cryogen that might be used where release of boil-off gas is flammable. In another example, the electrical control and / or monitoring system may be particularly useful for processing oxygen where release of oxygen could come into contact with a combustible material. It should be appreciated by a person skilled in the art, other cryogenic fluids may be stored in the cryogenic storage vessel 10.

[0079] In some configurations, the inert gas is helium gas, and the cryogenic liquid and cryogen gas is hydrogen. The helium gas isolates the heater(s) from the hydrogen in the liquid storage vessel. The helium prevents the hydrogen from entering the volume that contains the heater(s).

[0080] In some configurations, the inert gas is helium gas, and the cryogenic liquid and cryogen gas is oxygen. The helium gas isolates the heater(s) from the oxygen in the liquid storage vessel. The helium gas prevents the oxygen from entering the volume that contains the heater(s).

[0081] In some configurations, the inert gas is helium gas, and the cryogenic liquid and cryogen gas is natural gas. The helium gas isolates the heater(s) from the natural gas in the liquid storage vessel. The helium gas prevents the natural gas from entering the volume that contains the heater(s).

[0082] In some configurations, the inert gas is nitrogen gas, and the cryogenic liquid and cryogen gas is natural gas. The nitrogen gas isolates the heater(s) from the natural gas in the liquid storage vessel. The nitrogen gas prevents the natural gas from entering the volume that contains the heater(s). In some configurations, the inert gas is neon gas, and the cryogenic liquid and cryogen gas is oxygen. The neon gas isolates the heater(s) from the oxygen in the liquid storage vessel. The neon gas prevents the oxygen from entering the volume that contains the heater(s).

[0083] In some configurations, the inert gas is argon gas, and the cryogenic liquid and cryogen gas is oxygen. The argon gas isolates the heater(s) from the oxygen in the liquid storage vessel. The argon gas prevents the oxygen from entering the volume that contains the heater(s).

[0084] In some configurations, the inert gas is neon gas, and the cryogenic liquid and cryogen gas is natural gas. The neon gas isolates the heater(s) from the natural gas in the liquid storage vessel. The neon gas prevents the natural gas from entering the volume that contains the heater(s).

[0085] In some configurations, the inert gas is argon gas, and the cryogenic liquid and cryogen gas is natural gas. The argon gas isolates the heater(s) from the natural gas in the liquid storage vessel. The argon gas prevents the natural gas from entering the volume that contains the heater(s).

[0086] The electrical control and / or monitoring system 100 and / or storage vessel 10 may also contain one or more additional sensors within the storage vessel 10 that are not related to or necessary for the controlled boil-off system (such as liquid level or temperature or other properties). Those sensors will not have ignition sources that could come into contact with the cryogen. If the sensors do have possible ignition sources, they will be enclosed or there will be a sealed barrier between the possible ignition source and the interior storage space of the storage vessel. In some configurations, the system may have one or more temperature sensors configured to measure the temperature of a cryogen and / or cryogenic liquid within the cryogenic storage vessel 10. In some configurations, the system may have one or more pressure sensors configured to measure the pressure of a cryogen within the cryogenic storage vessel 10. The additional sensors may be located in the inert volume. Figure 1 shows an example of a pressure sensor 40 for measuring the pressure of the cryogen within the storage vessel. The pressure of the cryogen is an input to the control of the system. As described earlier, the pressure of the inert gas in the enclosure is higher than the pressure of the cryogen in the storage vessel. Due to this pressure difference, any leakage will be the higher pressure inert gas leaking into the storage vessel.

[0087] If the inert gas pressure were to reduce to a pressure that is close to the storage vessel pressure, for example due to the inert gas leaking into the storage vessel, the system will isolate the heaters (or other electrical components) from the power source. In other words, the system has a safety shutdown mechanism that discontinues power supply to the heater based on a comparison between the pressure of the enclosure and the storage vessel. Figure 1 shows the pressure sensor 40 is mounted directly to the tank.

[0088] In addition to the safety features described above, the enclosure is protected from overpressure with a safety device / devices. For example, the enclosure may have one or more safety valves that release the inert gas to atmosphere if it reaches a predetermined pressure.

[0089] This electrical control and / or monitoring system for use with a cryogenic storage vessel 10 may be particularly useful where the product is flammable or combustible, or is otherwise undesirable to be in contact with a source of ignition.

[0090] To those skilled in the art to which the invention relates, many changes in construction and widely differing embodiments and applications of the invention will suggest themselves without departing from the scope of the invention as defined in the appended claims. The disclosures and the descriptions herein are purely illustrative and are not intended to be in any sense limiting. Where specific integers are mentioned herein which have known equivalents in the art to which this invention relates, such known equivalents are deemed to be incorporated herein as if individually set forth.

Claims

CLAIMS1. An electrical control and / or monitoring system for use with a cryogenic storage vessel comprising: an electrical component; an enclosure surrounding the electrical component; an inert volume within the enclosure between the electrical component and the enclosure; a control system comprising one or more pressure sensors configured to measure the pressure of the inert volume, and one or more pressure sensors configured to measure the pressure of a cryogen and / or cryogenic liquid within the cryogenic storage vessel, the control system configured to regulate the electrical component based on pressure data from the one or more pressure sensors configured to measure the pressure of the inert volume, and the one or more pressure sensors configured to measure the pressure of a cryogen and / or cryogenic liquid within the cryogenic storage vessel.

2. The electrical control and / or monitoring system of any one of the preceding claims, wherein the inert volume comprises an inert gas.

3. The electrical control and / or monitoring system of any one of the preceding claims, wherein the inert volume is an inert gas.

4. The electrical control and / or monitoring system of any one of the preceding claims, further comprising a power source for providing power to the electrical component.

5. The electrical control and / or monitoring system of claim 4, further comprising electrical wires electrically connecting the power source to the electrical component.

6. The electrical control and / or monitoring system of any one of the preceding claims, wherein the enclosure comprises a conduit surrounding at least part of the length of the electrical wires.

7. The electrical control and / or monitoring system of any one of the preceding claims, wherein the enclosure comprises a conduit surrounding a major part of the length of the electrical wires.

8. The electrical control and / or monitoring system of any one of the preceding claims, wherein the enclosure comprises a conduit surrounding the entire length of the electrical wires.

9. The electrical control and / or monitoring system of any one of the preceding claims, wherein the enclosure comprises a reservoir providing an additional inert volume.

10. The electrical control and / or monitoring system of any one of the preceding claims, further comprising one or more temperature sensors configured to measure the temperature of the inert volume.

11. The electrical control and / or monitoring system of any one of the preceding claims, further comprising one or more temperature sensors configured to measure the temperature of a cryogen and / or cryogenic liquid within the cryogenic storage vessel.

12. The electrical control and / or monitoring system of any one of the preceding claims, wherein the inert gas is helium gas.

13. The electrical control and / or monitoring system of any one of claims 1 to 12, wherein the inert gas is neon gas, argon gas, krypton gas, or nitrogen gas.

14. The electrical control and / or monitoring system of any one of claims 1 to 12, wherein the inert gas is a combination of two or more of neon gas, argon gas, krypton gas, or nitrogen gas.

15. A cryogenic system comprising:the electrical control and / or monitoring system of any one of the preceding claims; a cryogenic storage vessel comprising: an inner wall defining a containment volume within the inner wall for containing the cryogenic fluids; an outer wall defining an external periphery of the cryogenic storage vessel; the inner wall spaced inwardly from the outer wall; and an insulation volume between the outer wall and inner wall wherein the inert volume within the enclosure has a pressure and the cryogenic gas within the cryogenic storage vessel has a pressure, the pressure of the inert volume within the enclosure being greater than the pressure of the cryogenic gas within the cryogenic storage vessel.

16. The cryogenic system of claim 15, wherein the cryogenic storage vessel contains cryogenic liquid and cryogenic gas.

17. The cryogenic system of claim 15 or 16, wherein the inert gas has a pressure of about 100kPa to about 3000kPa.

18. The cryogenic system of any one of claims 15 to 17, wherein the cryogenic gas has a pressure of about 10kPa to about WOOkPa.

19. The cryogenic system of any one of claims 15 to 18, wherein the cryogenic fluid in the storage vessel is hydrogen.

20. The cryogenic system of any one of claims 15 to 18, wherein the cryogenic fluid in the storage vessel is oxygen.

21. The cryogenic system of any one of claims 15 to 18, wherein the cryogenic fluid in the storage vessel is natural gas.

22. The cryogenic system of any one of claims 15 to 21, further comprising a hazardous zone, the hazardous zone being an area that contains the cryogenic storage vessel; and a non-hazardous zone, the non-hazardous zone being a location in which the levels of the cryogens are not flammable or where the cryogens do not exist, the non-hazardous zone being separated from the hazardous zone by distance and / or a physical barrier.

23. The cryogenic system of claim 22, wherein the control system comprises a control interface located in the non-hazardous zone NHZ.

24. The cryogenic system of claim 22 or claim 23, wherein the control system comprises a power source located in the non-hazardous zone.

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