Systems and methods for the storage and delivery of ammonia

Abstract

A system (200) for safely storing ammonia below the earth's surface includes a storage tank (300) located underground for storing liquid ammonia, and a safety system (400) connected to the storage tank (300) to control leakage from the storage tank (300) and to enable transfer of liquid ammonia into and out of the storage tank (300), the safety system (400) including a reliquefaction system (410), a recovery tank (420), a scrubber (430), a water tank (440), a backup external cooling system (450), and a liquid ammonia transfer system (460).

Description

Detailed Description of the Invention

[0001] [Field] The present invention relates to the storage and transfer of ammonia. More particularly, the present invention relates to the safe storage of ammonia in proximity to human populations, such as in or around urban ports, and to a transfer device for reducing the risk of dangerous leakage of ammonia from the transfer system.

[0002] [background] Ammonia is used and stored in industry for a wide variety of purposes, and if it is leaked, it can cause immediate and / or severe effects on people and / or the environment.

[0003] Ammonia is an inorganic compound of nitrogen and hydrogen with the chemical formula NH3. Ammonia is typically stored in refrigerated ammonia tanks. In liquid form, ammonia is stored at atmospheric pressure, approximately -33 degrees Celsius. Ammonia can also be stored at ambient temperature under elevated pressure. Additionally, ammonia can be stored in a semi-frozen state at intermediate pressures and temperatures.

[0004] Examples of uses for ammonia include as a fertilizer in agriculture, as an energy carrier for storing excess energy from energy plants, and as a fuel in the shipping industry and in power generation. For the latter two examples, large amounts of ammonia usually need to be stored. When fueled ships are used, the storage tanks should preferably be close to the port where the bunkering operation will take place.

[0005] However, ammonia is toxic, and safety measures must be taken to avoid the risk of human exposure. During the storage of ammonia, it is extremely important that ammonia does not leak in gas or liquid form. Leaked ammonia liquid may reach the atmosphere and boil. If leaked ammonia leaks into the sea, it may reach the surface and boil uncontrollably. Ammonia is very harmful to marine life and fish. Therefore, it is extremely important that ammonia does not leak from the storage tank.

[0006] As ammonia emerges as a viable fuel source for ships, larger ships will often need to dock and be able to refuel at urban ports or other ports in close proximity to larger populations or infrastructure.

[0007] It would be highly desirable to provide a safe ammonia storage system and method for storing ammonia such that the system could be located in close proximity to populated areas. Currently, ammonia is stored in large tanks at or adjacent to ports. Bunkering the ammonia, i.e., transferring the ammonia from the storage tanks to the ship, requires that the ammonia-fueled ship be in close proximity to the tanks.

[0008] Large storage tanks consume a lot of valuable space, especially in congested urban ports. Furthermore, large storage tanks are undesirable for many of the communities surrounding the port because they are so large and block much of the horizon. Residents within the communities may also feel uneasy living in close proximity to large, visible chemical storage tanks. Finally, there are often safety zones imposed around large ammonia storage tanks. Within the safety zones, people cannot work or live, and therefore the de facto space consumed by ammonia storage tanks is often much greater than their actual physical space consumption.

[0009] It would be highly desirable to provide a system and method for storing ammonia in densely populated areas, such as urban ports, that addresses at least some of the problems discussed above. Furthermore, bunkering of ammonia requires the same guaranteed safety from leakage and safety zones mentioned above.

[0010] Therefore, there is a need to minimize or eliminate the safety distance required during bunkering of ammonia. Additionally, there is a need to improve safety when bunkering ammonia.

[0011] Patent document US4796676A discloses a storage tank system for storing fluids in an environmentally safe container comprising a rigid outer first tank with a flexible protective second inner tank positioned within the tank and brought into contact with the inner wall of the rigid outer tank by negative pressure. A continuous monitoring system is connected to and forms part of the system used to evacuate the space between the inner and outer tanks, so that any leaks or integrity defects occurring in the liner can be immediately detected at any time.

[0012] Patent document US5381923A discloses overflow control for a liquid storage tank. Fluid overflow from the inlet port or vent port of the liquid storage tank is collected in an overflow collection chamber overlapping the inlet port and vent port. The overflow collection chamber also overlaps with an overflow storage chamber that receives liquid from the overflow collection chamber when the liquid in the overflow collection chamber rises to a level sufficient to flow into the inlet port of the overflow storage chamber. The overflow collection chamber is formed in a fluid-tight relationship with the storage tank and the overflow storage chamber. The liquid storage tank may also be located within a bund that includes a second overflow collection chamber for capturing overflow from the tank overflow collection chamber.

[0013] Patent document US4542626A details that when a product, such as ammonia, that can be liquefied under pressure and mixed with water, is stored underground, the storage is carried out at the liquefaction pressure of the product inside a double skin that defines an intermediate space, both skins being fitted into a cavity formed by a water-impregnated structure. The storage depth is selected so that the hydrostatic pressure of the water in the structure is greater than the maximum expected pressure of the product to be stored, and the intermediate space is filled with water and maintained at a pressure lower than the minimum expected pressure of the product to be stored. If a hole is opened in the inner skin, NH3 is collected in the water within the shaft and does not leak out and contaminate the water around the structure.

[0014] Patent document WO2018101841A1 discloses a hose device for transferring a flowable medium between a first unit and a second unit. The hose device comprises a hose unit having a first conduit suitable for transferring the medium and a second conduit arranged around the first conduit such that an enclosed space is formed between the first and second conduits. The hose device comprises a loop device having an inlet for injecting gas into the space and an outlet for removing gas from the space, and a control unit suitable for controlling the flow of the medium through the first conduit and the flow of gas through the loop device in a blocking phase so that the flow of the medium through the first conduit is blocked before blocking the flow of gas through the loop device.

[0015] SUMMARY OF THE INVENTION The present invention has as its object to ameliorate or mitigate at least one of the disadvantages of the prior art, or at least to provide a useful alternative to the prior art. This object is achieved through the features, which are set out in the following description and the claims that follow.

[0016] [overview] According to a first aspect of the present invention, there is provided a system for safely storing ammonia below the earth's surface, comprising: a storage tank located underground for storing liquid ammonia; a safety system connected to the storage tank for controlling leakage from the storage tank and for enabling transfer of the liquid ammonia into and out of the storage tank, the safety system including a re-liquefaction system configured to receive and liquefy boiling ammonia gas from the liquid ammonia in the storage tank and deliver the liquefied ammonia to the storage tank; a recovery tank configured to recover leaked liquid ammonia from the safety system and deliver the leaked liquid ammonia to the storage tank; and a safety system configured to treat leaked ammonia gas from the safety system and deliver the treated gas through a carbon filter to the atmosphere or the sea. a water tank connected to the scrubber and configured to receive contaminated water; a pre-external cooling system configured to operate to pre-cool the storage tank and the recovery tank; and a liquid ammonia transfer system configured to transfer liquid ammonia into and out of the storage tank, wherein the re-liquefaction system is configured to cool the storage tank and the recovery tank as a result of liquefaction of the ammonia gas, the liquid ammonia transfer system comprising: an outer fluid communication conduit; and a first inner fluid communication conduit disposed within the outer fluid communication conduit and configured to transfer liquid ammonia from a proximal end to a distal end, the first inner fluid communication conduit comprising a safety hose such that, during use, leakage of liquid ammonia from the first inner fluid communication conduit will be received in the outer fluid communication conduit.

[0017] The storage tank may be configured to withstand an internal pressure of at least 2 bar, or at least 3 bar, or at least 4 bar, or at least 5 bar.

[0018] The reliquefaction and recovery tank may be configured to withstand internal pressure. The storage tank is 1,000m 3 From 40,000m 3 The storage capacity may be between . The storage tank may include walls, a floor, and a roof, where the walls and / or floor are made of concrete and the roof includes a steel structure.

[0019] The roof of the storage tank may be covered with soil. The roof may be welded or bolted to the walls and / or floor. The system may further include a reliquefaction conduit in fluid communication with the reliquefaction system and the recovery tank, and a recovery tank conduit in fluid communication with the recovery tank and the storage tank, wherein the reliquefaction system is configured to cool the reliquefaction conduit and the recovery tank conduit as a result of liquefaction of the ammonia gas.

[0020] The reliquefaction system may be configured to cool the reliquefaction conduit and the recovery tank conduit so that the internal temperature of the reliquefaction conduit and the recovery tank conduit is between -10 and -35°C, or approximately -20°C.

[0021] The water tank is 100m 3 From 15,000m 3 The capacitance may be between .times. ... The system may further comprise a chimney connected to the scrubber to allow the treated gas to be released into the atmosphere.

[0022] The reliquefaction system may be configured to cool the storage tank so that the internal temperature of the storage tank is between -5 and -50°C, or between -30 and -40°C. The reliquefaction system may be configured to cool the recovery tank so that the internal temperature of the recovery tank is between -10 and -35°C, or approximately -20°C.

[0023] The auxiliary external cooling system may comprise at least one freeze pipe located underground in sufficient proximity to the storage tank such that the at least one freeze pipe may cool the storage tank so that the internal temperature of the storage tank is between -5 and -40°C, or between -30 and -40°C, during use.

[0024] The at least one frozen pipe may be located underground within 2 to 10 m, or 4 to 8 m, or approximately 5 m from the storage tank. The at least one freeze pipe may be located underground in sufficient proximity to the collection tank such that the at least one freeze pipe may cool the collection tank so that the internal temperature of the collection tank is between -10 and -35°C, or approximately -20°C, during use.

[0025] The at least one freezing pipe may be located underground within 2 to 10 m, or 4 to 8 m, or approximately 5 m from the collection tank. The at least one freeze pipe may comprise a plurality of freeze pipes.

[0026] The auxiliary external cooling system may further comprise a removable cooling unit configured to connect with the at least one freeze pipe for cooling the at least one freeze pipe.

[0027] The outer fluid communication conduit may be a flexible tube. The first inner fluid communication conduit may be a flexible tube. The outer fluid communication conduit may be configured to transport liquid ammonia and / or gas.

[0028] The outer fluid communication conduit may be configured, in use, to transfer liquid to the proximal end such that, in use, any leakage of liquid ammonia from the first inner fluid communication conduit will be received within the outer fluid communication conduit and may be conveyed to the proximal end.

[0029] The outer fluid communication conduit may be configured to transfer gas from the distal end to the proximal end such that, in use, liquid ammonia is passed from the proximal end to the distal end within the first inner fluid communication conduit while gas is conveyed from the distal end to the proximal end.

[0030] The system may further comprise a second inner fluid communication conduit disposed within the outer fluid communication conduit and configured to transfer gas from the distal end to the proximal end such that during use liquid ammonia is passed from the proximal end to the distal end in the first inner fluid communication conduit while gas may be conveyed from the distal end to the proximal end in the second inner fluid communication conduit, and any leakage of gas from the second inner fluid communication conduit will be received in the outer fluid communication conduit and may be conveyed to the proximal end.

[0031] The liquid ammonia transfer system may further comprise a second safety hose for transferring gas from the distal end to the proximal end of the second safety hose, the second safety hose comprising a second outer fluid communication conduit and a second inner fluid communication conduit disposed within the second outer fluid communication conduit and configured to transfer gas from the distal end to the proximal end of the second safety hose, such that leakage of gas from the second inner fluid communication conduit during use will be received in the second outer fluid communication conduit.

[0032] The system may further comprise a safety connector for connecting a safety hose to the delivery port in use for safe transfer of liquid ammonia from the inner fluid communication conduit to the delivery port, the connector comprising a connector body having a hose connection end and a port connection end; outer conduit connection means configured to provide a fluid-tight connection between the hose connection end of the connector body and the outer fluid communication conduit of the safety hose in use; first inner conduit fixation means disposed within the connector body and configured to fix the first inner conduit to the connector body in use such that the first inner conduit may be connected to a fluid receiving conduit of the port inside the connector body in use; and port connection means configured to provide a fluid-tight connection between the port connection end of the connector body and the delivery port in use, such that leakage of liquid ammonia from the first inner conduit within the connector body will be contained within the connector body.

[0033] The connector body may be frusto-conical. The connector body may be configured to transfer liquid ammonia. The connector body may be configured to transfer liquid to the hose connection end during use such that any leakage of liquid ammonia from the first inner fluid communication conduit within the connector body during use will be received by the connector body and may be conveyed to the hose connection end.

[0034] The connector body may be configured to transfer gas from the delivery port to the hose connection end during use such that, during use, liquid ammonia is passed through the safety connector in the first inner fluid communication conduit while gas is conveyed from the delivery port to the hose connection end.

[0035] The system may further comprise a second inner conduit securing means disposed within the connector body and configured to secure the second inner conduit of the safety hose to the connector body in use such that, in use, the second inner conduit may be connected with a gas supply conduit of the port inside the connector body.

[0036] The hose connection end of the connector body may be in fluid-tight connection with the outer fluid communication conduit of the safety hose by outer conduit connection means, and the first inner conduit is secured to the connector body by first inner conduit securing means.

[0037] According to a second aspect of the present invention, there is provided a method for safely storing ammonia underground and safely transferring ammonia, comprising the steps of providing a system according to the first aspect of the present invention; supplying a quantity of liquid ammonia to a storage tank; operating a re-liquefaction system to cool the storage tank and a recovery tank as a result of liquefaction of the ammonia gas, such that the liquid ammonia in the storage tank receives and liquefies boiling ammonia gas, and delivers the liquefied ammonia to the storage tank; and transferring the ammonia through the first inner fluid communication conduit from the proximal end to the distal end of the hose, such that any leakage of ammonia from the first inner fluid communication conduit will be received in the outer fluid communication conduit.

[0038] The method may further include collecting any liquid ammonia leaked from the safety system in a collection tank and delivering the leaked liquid ammonia to a storage tank. The method may further include treating the ammonia gas leaked from the safety system in a scrubber and sending the treated gas through a carbon filter into the atmosphere or into the sea, and collecting contaminated water from the scrubber in a water tank.

[0039] The method may further include operating a backup external cooling system to cool the storage tank and the recovery tank. The method may further include transferring the liquid ammonia into or out of the storage tank using a liquid ammonia transfer system. [Brief explanation of the drawings]

[0040] Embodiments of the present invention will now be described with reference to the following drawings. [Figure 1] Figure 1 shows an ammonia storage and delivery system located at a city port. [Figure 2] 2 shows an alternative view of the ammonia storage and delivery system of FIG. 1. [Figure 3] 1 shows a cross-section through a first example of an ammonia storage and delivery system. [Figure 4] 1 shows a cross-section through a second example of an ammonia storage and delivery system. [Figure 5] A robot and a hose are shown. [Figure 6] The robot of FIG. 5 is shown with a hose connected to the end effector of the robot. [Figure 7] 1 shows a safety hose configured to transfer ammonia. [Figure 8] 8 shows a connector to be placed on the end of the safety hose of FIG. 7. [Figure 9]10 illustrates an alternative safety hose with a single inner fluid communication conduit and configured to allow gas to return within an outer fluid communication conduit. [Figure 10] 1 shows a kit with first and second safety hoses. [Figure 11] 11 shows a connector for connecting the first or second safety hose of FIG. 10 to a delivery port. DETAILED DESCRIPTION OF THE INVENTION

[0041] [Detailed description of the drawings] 1 and 2 illustrate a site 100 that is desirable for storing and bunkering large quantities of liquid ammonia. The term bunkering is used throughout this disclosure and is intended to mean the transfer of ammonia from a storage location to a ship, storage container, vessel, or other vessel. In the examples presented herein, the bunkering is performed on a vessel; however, it will be understood that in some cases, the ammonia may be transferred to another vessel for storage or further transfer. Thus, the term bunkering is used broadly herein to refer to the transfer or delivery of ammonia from a storage tank to a vessel, or vice versa.

[0042] 1 and 2, site 100 includes a port 101, several industrial buildings 102, agricultural land 103, and a residence 104. It will be appreciated that at other sites where it is desirable to store large quantities of liquid ammonia, such as a large urban port, there may be more buildings, infrastructure, residences, and other aspects of the built environment in close proximity.

[0043] Port 101 has a vessel 105 docked and connected to an ammonia storage and transfer system 200 for storing and transferring liquid ammonia. It will be understood that vessel 105 may receive or transfer liquid ammonia to ammonia storage and transfer system 200.

[0044] 1 and 2, in the example described herein, ammonia storage and transfer system 200 can be seen to be located just below the ground surface in the port 101 area. It will be understood that in an alternative example (not shown), ammonia storage and transfer system 200 can be located below sand, rock, soil, mud, clay, or any other material found on the Earth's surface. Furthermore, in an alternative example, ammonia storage and transfer system 200 can be located in a mountain, for example, in a cavity that has been blown into or excavated from a mountain. While the term mountain is used herein, it will be understood that this term is used broadly and can refer to, for example, rolling hills. Further details of the construction of ammonia storage and transfer system 200 are provided below, following the description of the components of system 200.

[0045] With reference to Figure 3, details of the major components of system 200 are now provided. System 200 comprises a storage tank 300 having sidewalls 301, a floor 302, and a roof 303. Sidewalls 301 and floor 302 in the example described herein are formed of concrete and polymer. In other examples, sidewalls 301 may be constructed as secant walls, which provides a suitable construction method for forming a sealed storage tank 300 within an underground cavity. Alternatively, sidewalls 301 may be formed of steel. Alternatively, sidewalls 301 may be formed as slurry walls. Alternatively, sidewalls 301 may be formed of one or more flexible membranes.

[0046] In some instances, the sidewall 301 will be made entirely of concrete. In some instances, the sidewall 301 will be made of several alternating layers of concrete and polymer. Polymer may be used when the sidewall 301 is constructed on unstable bedrock and / or when additional safety barriers are needed.

[0047] The roof 303 in the examples described herein is a truss structure and is formed of steel. In some examples, the roof 303 may be welded to the side walls 301. In some examples, the roof 303 may be bolted to the side walls 301. The roof 303 may be constructed to withstand high internal pressure in some examples by forming the roof 303 in a single or double curved shape. Additionally or alternatively, the roof 303 may be provided with vertical tension rods that connect to the side walls 301 or the floor 302. The storage tank 300 in the examples described herein has a capacity of approximately 15,000 m 3 In some examples, the storage capacity is 1,000 m 3 From 40,000m 3 It may be between.

[0048] As can be seen in Figure 3, the storage tank 300 is located below ground level. In the example described herein, the roof 303 is just below ground level and is covered by a thin layer of rock and soil 304. It will be appreciated that in alternative examples, the storage tank 300 may be located significantly deeper underground; that is, in some examples, there may be a thicker layer of rock and soil 304 covering the roof 303. In some examples, the layer of rock and soil 304 may be between 3 m and 20 m thick.

[0049] 3, it can be seen that storage tank 300 is connected to a safety system 400 to control leakage from storage tank 300 and to enable the transfer of liquid ammonia into and out of storage tank 300, i.e., ammonia bunkering. Safety system 400 includes a reliquefaction system 410, a recovery tank 420, a scrubber 430, a water tank 440, a backup external cooling system 450, and a liquid ammonia transfer system 460. Each of these components will be described in more detail below.

[0050] Liquid ammonia at atmospheric pressure has a boiling point of approximately −35.7° C. Therefore, the storage tank 300 containing the liquid ammonia must be maintained at a very low temperature at all times to ensure that rapid and uncontrollable boiling of the ammonia does not occur.

[0051] Maintaining liquid ammonia at a temperature below −37.5° C. is highly desirable to ensure that boiling does not occur, however, this is challenging and presents practical technical difficulties, particularly when storage tank 300 is used for loading and unloading ammonia, such as bunkering ammonia onto a ship.

[0052] Therefore, some (very slight) boiling of ammonia, resulting in the evolution of ammonia gas, is permitted. The storage tank 300 in the examples described herein is configured to withstand an internal pressure of at least 2 bar. In some examples, the storage tank 300 may be configured to withstand an internal pressure of at least 3 bar, or at least 4 bar, or at least 5 bar. The storage tank 300 is configured to withstand an internal pressure that can safely build up within the storage tank 300 without causing the storage tank 300 to explode or rupture. While minimizing ammonia boiling is highly desirable, some boiling is unavoidable. Boiling of ammonia inside the storage tank 300 causes an increase in internal pressure that the storage tank 300 must withstand.

[0053] Furthermore, it is highly desirable that storage tank 300 be configured to withstand internal pressures much greater than those expected during operation, i.e., those that arise during use when small amounts of ammonia boil due to heat entering storage tank 300 during transfer of ammonia into or out of storage tank 300. It should be noted that the internal temperature of storage tank 300 may also rise for other reasons. This provides a safety factor such that if it is not possible to maintain storage tank 300 at a temperature low enough to minimize ammonia boiling during use, then the internal pressure within storage tank 300 may safely rise for a reasonable period of time until pre-cooling can be effected and / or storage tank 300 can be emptied of ammonia. This will be explained in more detail below.

[0054] Reliquefaction system 410 is configured to receive and liquefy ammonia gas that has boiled off from the liquid ammonia in storage tank 300, and deliver the liquefied ammonia to storage tank 300. Some boiling of the ammonia in storage tank 300 is thereby tolerable because the ammonia gas is converted back to a liquid and then delivered back to storage tank 300. A convenient advantage of reliquefaction system 410 is that the process of converting ammonia gas back to liquid ammonia provides a cooling effect. That is, reliquefaction system 410 serves to provide cooling during operation. This cooling cools storage tank 300 in an attempt to maintain the internal temperature of storage tank 300 as low as possible.

[0055] In other words, operation of reliquefaction system 410 can be considered a cyclical process involving storage tank 300. At the start of a cycle, some of the liquid ammonia in storage tank 300 boils because the internal temperature of storage tank 300 is higher than the boiling point of ammonia at the pressure inside storage tank 300. Ammonia gas is supplied to and liquefied in reliquefaction system 410, which cools storage tank 300 during liquefaction, thereby preventing further or uncontrollable boiling. In this regard, reliquefaction system 410 serves to cool storage tank 300 when cooling is needed because the liquid ammonia inside storage tank 300 would boil due to the temperature of the liquid ammonia. Reliquefaction system 410 in the example described herein is configured to cool storage tank 300 so that the internal temperature of storage tank 300 is between −5 and −50° C. In some examples, the reliquefaction system 410 may be configured to cool the storage tank 300 so that the internal temperature of the storage tank 300 is between -30 and -40 degrees Celsius.

[0056] Alternatively, and for purposes of explanation only, reliquefaction system 410 may be thought of as a cooling system for storage tank 300, whereby cooling is provided only when the temperature inside storage tank 300 becomes high enough for boiling of the liquid ammonia to occur.

[0057] Reliquefaction systems are well known in the art and it would be within the ability of one skilled in the art to select an appropriate reliquefaction system for the purposes described. It will be appreciated that some liquid ammonia may leak from safety system 400 during operation. For example, some liquid ammonia may leak from re-liquefaction system 410. Recovery tank 420 is configured to recover any liquid ammonia that leaks from safety system 400 and deliver the leaked liquid ammonia to storage tank 300.

[0058] 3 , safety system 400 includes a reliquefaction conduit fluidly connecting reliquefaction system 410 and recovery tank 420, and a recovery tank conduit fluidly connecting recovery tank 420 and storage tank 300. In some examples, reliquefaction system 410 may deliver liquefied ammonia to storage tank 300 via recovery tank 420. In alternative examples, reliquefaction system 410 may deliver liquid ammonia directly to storage tank 300. In either case, the reliquefaction conduit may be configured to capture any leaked liquid ammonia from reliquefaction system 410 and deliver it to recovery tank 420. In the examples described herein, reliquefaction system 410 and recovery tank 420 are configured to withstand internal pressure.

[0059] It will be understood that recovery tank 420 is intended to recover liquid ammonia and maintain the liquid ammonia in a liquid phase within recovery tank 420 before it is delivered to storage tank 300. The reliquefaction conduit and recovery tank conduit are further intended to also maintain the liquid ammonia in a liquid phase during its transfer therethrough. In this regard, recovery tank 420, reliquefaction conduit, and recovery tank conduit are all maintained at low temperatures to maintain the liquid ammonia in a liquid phase therein. Cooling of recovery tank 420, reliquefaction conduit, and recovery tank conduit may be provided by reliquefaction system 410 in the same manner as reliquefaction system 410 cools storage tank 300 (as described above). In addition to, or instead of, this cooling, recovery tank 420, reliquefaction conduit, and recovery tank conduit may be kept cool by an external cooling system. It will be appreciated that the reliquefaction system 410 and the fluid communication conduits may be significantly smaller than the storage tank 300, and therefore it may be possible to cool these components by external cooling means. However, it is particularly advantageous if the cooling of these components is provided by the reliquefaction system 410, thereby eliminating the need for an external cooling system.

[0060] Regardless of the means for cooling the recovery tank 420 and the reliquefaction and recovery tank conduits, it is preferred to maintain the internal temperatures of these components between -10 and -35°C, or approximately -20°C.

[0061] 3, the scrubber 430 is configured to treat ammonia gas leaked from the safety system 400. Scrubbers 430 are well known in the art, and it would be within the ability of one skilled in the art to select an appropriate scrubber 430 for treating ammonia gas. In some examples, the scrubber 430 may be connected to a chimney 431 arranged to deliver the treated ammonia gas to the atmosphere. After treatment, the ammonia gas is essentially air with minimal ammonia in the atmosphere. Therefore, the treated gas can simply be released into the atmosphere without posing any danger to humans or causing any unpleasant odors on the ground. 15,000 m 3 For a storage tank such as in the example described herein, the chimney 431 may be configured to release the treated gas approximately 15 to 20 m above ground level.

[0062] In other examples, the treated ammonia gas may be delivered to the seawater by a direct connection between the scrubber 430 and a subsea exhaust pipe. In some examples, the safety system 400 may include both a chimney 431 for venting the treated ammonia gas to the atmosphere and a subsea exhaust pipe for delivering the treated ammonia gas to the seawater. In such cases, the safety system 400 may be able to switch between venting the treated gas to the atmosphere and venting it to the seawater. In some cases, the ability to switch between venting to the atmosphere, i.e., air, and venting to the seawater may only be provided as a redundancy to ensure that the treated ammonia gas can be vented at any time if it becomes unsafe or undesirable to continue venting the treated ammonia gas in the preferred manner. For example, if the system 400 is configured to vent the treated ammonia gas to the atmosphere via the chimney 431, as described above, and personnel must work near the chimney 431 during operation, it may be highly desirable to switch to venting to the seawater if the system is configured to provide such a switching capability. Additionally, if a preferred method of venting, such as venting to the atmosphere via chimney 431, is not possible due to a mechanical blockage of chimney 431, system 200 may alternatively vent to seawater, thereby still allowing safe venting of ammonia gas from system 400, thereby providing redundancy and improving the safety of system 200. In some examples, ammonia vented to the atmosphere may be combusted.

[0063] If ammonia gas is discharged into seawater, the scrubber 430 is preferably arranged with an activated carbon filter (not shown) so that the ammonia gas is delivered to the seawater through the activated carbon filter. Furthermore, the ammonia gas is preferably discharged into the sea at an appropriate depth. As an example, the ammonia gas may be discharged into the water at a depth of approximately 10 m. Furthermore, the discharge site in the sea may be provided with a device configured to break up the ammonia gas bubbles, thereby preventing the ammonia gas bubbles from immediately reaching the water surface, where the ammonia is absorbed into the water. One example of such a suitable device may be a multi-layer tank with perforated plates. It will be understood that other suitable devices may also be used.

[0064] The water tank 440 is fluidly connected to the scrubber 430 so that contaminated water from the scrubber 430 can be collected in the water tank 440 during use. The water tank 440 may be configured to hold the contaminated water for a period of time before the water tank 440 can be emptied. In this regard, the water tank 440 may be configured to hold a 100m 3 From 15,000m 3 The capacitance may be between .times. ...

[0065] The water tank 440 may be retractable from the system for emptying or may be provided with a fluid port or fluid connection above ground level for discharging contaminated water to a suitable large recovery vessel on land.

[0066] In some examples, if water tank 440 is provided with a large enough capacity to hold a sufficiently large amount of water within water tank 440, water tank 440 may be further configured to receive liquid ammonia, such as liquid ammonia that has leaked from other components of safety system 400. In this regard, safety system 400 may be arranged so that leaked liquid ammonia can be delivered to water tank 440 where it can mix with the water in water tank 440 and thereby be safely absorbed by the water. It should therefore be noted that water tank 440, when used to collect leaked ammonia, must be large enough so that the leaked ammonia can be safely absorbed by the water.

[0067] The auxiliary external cooling system 450 is configured to operate to provide auxiliary cooling to the storage tank 300 and the recovery tank 420. In this regard, the auxiliary external cooling system 450 in the example described herein includes a plurality of freeze pipes 451 and an external cooling unit 452. The plurality of freeze pipes 451 are inserted into the ground so that they surround the storage tank 300. In this regard, the freeze pipes 451 are located sufficiently close to or directly adjacent to the storage tank 300 so that a sufficient cooling effect can be provided to the storage tank 300. In some examples, the freeze pipes 451 may be located underground within 2 m to 10 m of the storage tank 300. In some examples, the freeze pipes 451 may be located underground within 4 m to 8 m of the storage tank 300. In some examples, the freeze pipes 451 may be located underground approximately 5 m from the storage tank 300. In some examples, a single freeze pipe 451 may be provided. In such a case, the freeze pipe 451 may be provided in a continuous ring around the periphery of the storage tank 300. If multiple freeze pipes 451 are provided, the multiple freeze pipes 451 are preferably evenly distributed around the periphery of the storage tank 300. In the example illustrated, the freeze pipe 451 extends down the side wall 301 of the storage tank 300. It will be understood that in other examples not shown, the freeze pipe 451 may also extend below the floor 302 of the storage tank 300.

[0068] During use, the external cooling unit 452 can be connected to the freeze pipe 451 to significantly reduce the temperature of the freeze pipe 451 so that the freeze pipe 451 can cool the storage tank 300. The freeze pipe 451 is installed underground adjacent to the storage tank 300; however, it is possible, but not necessary, for a permanent external cooling unit 452 to be installed on the surface. Alternatively, the freeze pipe 451 can be provided with a connection so that the freeze pipe 451 can be connected to the external cooling unit 452 when needed. In this way, the external cooling unit 452 can be connected to the freeze pipe 451 only when needed and, when not needed, can be utilized elsewhere. This saves space on the land above the storage tank 300 and also reduces the permanent equipment required at that location. Furthermore, a sufficiently powerful external cooling unit 452 may be expensive; therefore, providing the external cooling unit 452 only when actually required when pre-cooling is required may provide economic advantages.

[0069] Liquid ammonia transfer system 460 is configured to transfer liquid ammonia into and out of storage tank 300. Liquid ammonia transfer system 460 shown in Figure 3 is deployed in use and connected to a vessel, thereby enabling bunkering of ammonia from storage tank 300 to the vessel. The vessel comprises a hull 600 having a delivery port 610. Liquid ammonia transfer system 460 comprises a safety hose 461 for connection to delivery port 610 in use. Safety hose 461 is operated by a robot 462 to enable connection and disconnection of safety hose 461 to delivery port 610, as will be described below.

[0070] The safety hose 461 is configured such that, in use, any leaked liquid ammonia being transferred by the safety hose 461 will be captured by the safety hose 461 and may be transferred back to the storage tank 300. Furthermore, the ammonia gas in the safety hose 461 may, in use, be transferred to the scrubber 430 and / or the stack 431 for combustion and / or the re-liquefaction system 410. Further details of the safety hose 461 are provided below.

[0071] In the example described here, the safety hose 461 is connected to the intermediate container 480. As can be seen in Fig. 3, the safety hose 461 is angled steeply towards the intermediate container 480 so that any leaked liquid ammonia can flow downward into the intermediate container 480 where it is temporarily collected. The intermediate container 480 may be equipped with a pumping system to return the liquid ammonia towards the storage tank 300. In this regard, the connection between the intermediate container 480 and the storage tank 300 does not need to be at an inclined angle if a pumping system is provided. It will be understood that the intermediate container 480 may be equipped with appropriately arranged valves and / or liquid handling systems.

[0072] It will be appreciated that in alternative examples, if the safety hose can be maintained at an angle throughout its length and / or if pumping equipment can be integrated with the safety hose to pump back liquid or gas, intermediate container 480 may not need to be present.

[0073] In some examples, a control system may be provided to determine where the returning fluids (i.e., liquid and / or gas) should go. That is, the control system may decide to direct the returned ammonia gas to a scrubber, or, if a very large amount of ammonia gas is being returned, to a stack for combustion of the gas. Appropriate fluid connections may be provided between safety hoses and each of the scrubber, storage tank, stack, and re-liquefaction system.

[0074] With further reference to FIG. 3 , details of one possible construction method for forming an underground storage tank 300 are now described. As discussed above, the storage tank 300 may be located in a cavity formed by blasting or excavating a mountain. A preferred method for forming the cavity is using mechanical excavation. In some cases, the storage tank 300 is pre-formed and transported to the cavity as a substantially completed tank 300. In other cases, the storage tank 300 is constructed within the cavity as described herein. However, constructing the storage tank 300 within the cavity is problematic due to the fact that the cavity may fill with water as the excavation deepens below the water table.

[0075] A preferred solution to this is to begin construction of the storage tank 300 with the installation of freeze pipes 451 around the perimeter where the storage tank 300 will be located. In this regard, the freeze pipes 451 are placed in place within a hole drilled or excavated into the earth. The freeze pipes 451 are then connected to a cooling unit 452 and operate to cause ground freezing, freezing the water table where the excavation will be performed. During excavation, the water table remains frozen, allowing the cavity to be excavated without filling with water. After the cavity is formed, it is free of water, and concrete and polymer can be sprayed or otherwise attached to the interior walls of the cavity to form the side walls 301 and floor 302 of the storage tank 300. In some instances, alternating layers of concrete and polymer may be used. It should be noted that after the cavity is formed in the manner described above, the storage tank 300 may be constructed by other methods, such as the assembly of secant walls as previously discussed. As described above, the cooling unit 452 may then be removed and the frozen pipes 451 may be left underground near the storage tank 300 so that they can be used again in an emergency requiring rapid cooling of the storage tank 300.

[0076] Referring now to Figure 4, an alternative system 200' will now be described. System 200' is similar to system 200 described with reference to Figure 3, and therefore, like reference numerals are used in the example set forth in Figure 4 to indicate like parts, with the addition of a prime (').

[0077] System 200' comprises a storage tank 300' with sidewalls 301', floor 302', and roof 303' beneath rock and soil 304'. Storage tank 300' is connected to a safety system 400' to control leakage from storage tank 300' and to allow transfer of liquid ammonia into and out of storage tank 300'. Safety system 400' comprises a re-liquefaction system 410', a recovery tank 420', a scrubber 430' and stack 431', a water tank 440', a backup external cooling system 450' comprising freeze pipes 451' and external cooling unit 452', a liquid ammonia transfer system 460', and a safety buffer tank 470'.

[0078] The example shown in FIG. 4 is arranged to operate in substantially the same manner as the example described with reference to FIG. 3, except that the safety buffer tank 470′ provides a tank in which spilled ammonia can be stored in the event of an overfill of the storage tank 300′. In this regard, the safety buffer tank 470′ has a fluid connection with the storage tank 300′ to enable the transfer of spilled ammonia to the safety buffer tank 470′. The safety buffer tank 470′ may further include one or more sensors configured to detect ammonia within the safety buffer tank 470′. The one or more sensors may be arranged with appropriate electronics to alert an operator of the safety system 200′ to the presence of ammonia within the safety buffer tank 470′ and, therefore, an overfill of the storage tank 300′. Optionally, the system 200′ may include a control system configured to automatically stop filling the storage tank 300′ upon detection of ammonia by one or more sensors within the safety buffer tank 470′.

[0079] Continuing with reference to FIG. 4 , it can be further seen that in this example, system 200′ is disposed in an access road 500′ formed in the earth. In this regard, storage tank 300′ is formed as previously described, and access road 500′ is excavated during excavation of the cavity as a single deep road reaching from the earth's surface to the bottom of the cavity, providing a path for removing material during excavation. Access road 500′ is particularly convenient for disposing safety system 400′ within the formed access road 500′ after the cavity is formed and excavation of material through access road 500′ is completed, so that it is not backfilled after the cavity is fully formed. After safety system 400′ is positioned within access road 500′, all remaining free space around safety system 400′ may be backfilled to substantially bury safety system 400′ in the earth. The described method of using access road 500′ as a location for disposing safety system 400′ avoids the need for further excavation to provide an additional cavity for safety system 400′.

[0080] By locating the described system 200, 200' underground, the risk of fire and explosion is greatly reduced so that no above-ground safety zone, or only a minimal above-ground safety zone, may be required. This is particularly advantageous because it allows for the storage of ammonia in urban ports where ammonia bunkering occurs frequently, but where many people must live and work nearby. Furthermore, real estate at or near urban ports can often be very valuable, and thus it can be advantageous to consume no land area when discharging treated ammonia gas into the sea, or to consume very little land area when discharging treated ammonia gas into the air.

[0081] In the preferred embodiment described, it is desirable to keep the ammonia as cold as possible to minimize boiling. In this regard, the storage tanks 300, 300' are configured to operate near atmospheric pressure under normal conditions and to withstand much higher internal pressures in situations where excessive boiling occurs. In some instances, it may be desirable to configure the storage tanks 300, 300' to withstand higher internal pressures. In such instances, the ammonia may be pressurized inside the storage tanks 300, 300' during normal storage, and therefore the boiling point will be higher than at atmospheric pressure. In this regard, the ammonia may be stored at a pressure of 2.5 bar, and the storage tanks 300, 300' may be cooled slightly to, for example, -20°C to maintain a sufficiently low boiling point within the storage tanks 300, 300'. Also, in such cases, the maximum internal pressure that the storage tank 300, 300' can withstand may need to be increased to provide a safety factor to ensure that the storage tank 300, 300' does not explode or rupture if the temperature inside the tank increases, thereby causing an increase in internal pressure due to the boiling of ammonia, as described above.

[0082] In the illustrated example, the storage tanks 300, 300' do not require insulation to prevent heating from the surroundings. It will be appreciated that the water tanks 440, 440' of the illustrated systems 200, 200' may be maintained at temperatures above 0° C. so that they do not freeze. For example, the water tanks 440, 440' may be provided with insulation and / or heating capabilities. Furthermore, the water tanks 440, 440' may be located away from the storage tanks 300, 300' so that the water tanks 440, 440' can be maintained sufficiently warm so that the water tanks 440, 440' do not freeze when the storage tanks 300, 300' are maintained at low temperatures.

[0083] Although not described in detail, it will be understood that operation of the systems 200, 200' may be performed from a remote location. In this regard, the systems 200, 200' may not require personnel to be present in the vicinity. It will be understood that monitoring, control, and emergency response may all be accomplished remotely via an appropriately configured wireless or wired communication system.

[0084] During operation, the storage tank 300, 300' may store any amount of ammonia up to 100% of the storage capacity of the tank 300, 300'. For practical reasons, it may be desirable to fill the tank to a practical maximum of between 90% and 95% full. In the example where the tank 300, 300' is at its practical maximum, i.e., approximately 95% full, there will be a remaining 5% free space within the tank 300, 300' that acts as a gas buffer volume.

[0085] In some examples, the storage tank 300, 300' may not be completely filled. In some examples, the storage tank 300, 300' may only be filled, for example, to between 70% and 90% of the tank's 300, 300' capacity, or to approximately 80% of the tank's 300, 300' capacity. When 80% full, a 20% gas buffer volume exists. All the boiling ammonia will cause the pressure in the storage tank 300, 300' to rise more rapidly when only a 5% gas buffer volume exists compared to when a 20% gas buffer volume is provided. Therefore, the operational safety of the system 200, 200' may be improved by providing a larger gas buffer volume.

[0086] In some instances, it may be desirable to operate the external cooling system 450, 450' at all times while ammonia is present in the storage tank 300, 300'. This may provide an additional safety barrier, as operation of the external cooling system 450, 450' will cause any groundwater surrounding the storage tank 300, 300' to freeze. The reaction between ammonia and ice is very slow, and therefore, any ammonia leak through the walls 301, 301' or floors 302, 302' of the storage tank 300, 300' will take a long time to penetrate the surrounding ice.

[0087] In some examples, the storage tank 300, 300' may include a number of sensors located around the walls 301, 301' and floor 302, 302' of the tank 300, 300' and configured to detect leaked ammonia.

[0088] 5 and 6, further details of the robot 462 of the safety system 400 shown in FIGS. 1-3 will now be provided. While the term robot is used herein, it will be understood to include any basic robotic arm or manipulator. As previously discussed, the safety system 400 is located largely underground, with the exception of the robot 462 and at least a portion of the safety hose 461. Referring first to FIG. 5, the robot 462 includes an end effector 463 configured to engage and manipulate a connector 464 located at one end of the hose 461. As shown in FIG. 5, when the hose 461 is not transferring liquid ammonia, the hose 461 may be stored underground. The robot 462 can retrieve the hose 461 by connecting with the connector 464 and lifting the hose 461 above ground so that the connector 464 can be brought into engagement with the delivery port 610, as shown in FIG. 6. The described robot 462 may be used with the safety system 400′ of FIG. 4.

[0089] 7, further details of the safety hose 461 and connector 464 are now provided. The safety hose 461 is arranged to deliver liquid ammonia from a proximal end 461A to a distal end 461B of the hose 461.

[0090] Because the particular type or configuration of the robot 462 is not critical, the robot 462 is shown in simplified diagram form in FIG. 7 . In this regard, in the example described herein, the robot 462 is connected to the hose 461 by a first loop 462A and a second loop 462B configured to ensure that the hose 461 does not stray too far from the robot 462 during use. In some examples, the first loop 462A and the second loop 462B may also be configured to at least partially support the weight of the hose 461 during use. The robot 462 primarily manipulates the hose 461 through the connection between the robot 462 and a connector 464. The connector 464 is connected to the distal end 461B of the hose 461, and therefore, manipulation of the connector 464 also moves the hose 461. It will be understood that manipulation and / or movement of the hose 461 and the connector 464 may be effected in a myriad of ways.

[0091] 7, the hose 461 comprises an outer fluid communication conduit 4611 and first and second inner fluid communication conduits 4612, 4613. The first and second inner fluid communication conduits 4612, 4613 are disposed within the outer fluid communication conduit 4611.

[0092] First inner fluid communication conduit 4612 is configured to transport liquid ammonia (not shown) from proximal end 461A to distal end 461B. That is, hose 461 transports liquid ammonia from proximal end 461A to distal end 461B, and in particular, first inner fluid communication conduit 4612 is the component within hose 461 that provides such transport of liquid ammonia in normal use.

[0093] The described arrangement in which the outer fluid communication conduit 4611 is provided around the first inner fluid communication conduit 4612 carrying liquid ammonia provides an arrangement in which any leakage of liquid ammonia from the first inner fluid communication conduit 4612 will leak into the outer fluid communication conduit 4611. In this regard, any leakage of liquid ammonia from the first inner fluid communication conduit 4612 will not reach the environment outside the hose 461. In other words, any leaked liquid ammonia from within the first inner fluid communication conduit 4612 is captured within the outer fluid communication conduit 4611.

[0094] Still referring to FIG. 7, delivery port 610 is registered to include connector 464 such that connector 464 mates with delivery port 610 to enable liquid ammonia to be transferred from safety system 400 to delivery port 610 on the vessel hull 600.

[0095] Although not shown in the figures, the vessel may include a fluid storage tank or other suitable container configured to store or process the supplied ammonia. In this regard, when liquid ammonia is delivered from the safety system 400, gas (e.g., vapor from the liquid ammonia) may need to be removed in a safe manner. The second inner fluid communication conduit 4613 is configured to transfer gas from the distal end 461B to the proximal end 461A such that, during use, liquid ammonia is delivered from the proximal end 461A to the distal end 461B in the first inner fluid communication conduit 4612, while gas can be transported from the distal end 461B to the proximal end 461A in the second inner fluid communication conduit 4613. In this manner, gas can be removed in a safe manner. Furthermore, any leakage of gas from the second inner fluid communication conduit 4613 will be received in the outer fluid communication conduit 4611 and can be transported to the proximal end 461A. There are countless possible ways in which leaked gas can be carried to the proximal end 461A within the outer fluid communication conduit 4611. By way of example only and not by way of limitation, a suction device may be provided to suck leaked gas from the outer fluid communication conduit 4611 to the proximal end 461A.

[0096] In the examples described herein, the outer fluid communication conduit 4611 is a flexible tube. In some examples, the outer fluid communication conduit 4611 may be provided as a rigid tube. Similarly, in the examples described herein, the first inner fluid communication conduit 4612 and the second inner fluid communication conduit 4613 are flexible tubes. In some alternative examples, the first inner fluid communication conduit 4612 and the second inner fluid communication conduit 4613 may be provided as rigid tubes.

[0097] In the example described herein, the safety hose 461 is configured for use with ammonia. In this regard, the first inner fluid communication conduit 4612 is configured to transport liquid ammonia. Additionally, the outer fluid communication conduit 4611 is configured to transport liquid ammonia and gas such that any liquid ammonia leaking from the first inner fluid communication conduit 4612 can be received by the outer fluid communication conduit 4611. Providing suitable materials, manufacturing processes, thicknesses, etc. for the transport of liquid ammonia in the first inner fluid communication conduit 4612 and liquid ammonia and gas in the outer fluid communication conduit 4611 would be within the capabilities of one skilled in the art.

[0098] Further details of the safety connector 464 will now be provided with reference to Figure 8. As previously described, the safety connector 464 is configured to mate with a delivery port 610 for the transfer of ammonia. The delivery port 610 is provided with a first port conduit 611 and a second port conduit 612. As can be seen in Figure 8, the first port conduit 611 engages with a first inner fluid communication conduit 4612 of the hose 461, and the second port conduit 612 engages with a second inner fluid communication conduit 4613 of the hose 461, thereby enabling the transfer of liquid ammonia and gas, as previously described. The connector 464 comprises a connector body 4641 having a hose connection end 464A and a port connection end 464B. The hose connection end 464A comprises an outer conduit connection means 4642 configured to provide a fluid tight connection between the hose connection end 464A of the connector body 4641 and the outer fluid communication conduit 4611 of the safety hose 461 during use.

[0099] The connector 464 further comprises a first inner conduit fixation means 4643 disposed within the connector body 4641 and configured to fix the first inner fluid communication conduit 4612 to the connector body 4641 in use such that the first inner fluid communication conduit 4612 may be connected with the first port conduit 611 within the connector body 4641. The connector 464 further comprises a second inner conduit fixation means 4644 disposed within the connector body 4641 and configured to fix the second inner fluid communication conduit 4613 to the connector body 4641 in use such that the second inner fluid communication conduit 4613 may be connected with the second port conduit 612 within the connector body 4641.

[0100] In the example described here, the first inner conduit fixing means 4643 and the second inner conduit fixing means 4644 are provided as a first bracket 4645 and a second bracket 4646 with a first clamp 4647 and a second clamp 4648 configured to hold the first inner fluid communication conduit 4612 and the second inner fluid communication conduit 4613 fixedly in place so that the first inner fluid communication conduit 4612 and the second inner fluid communication conduit 4613 can be connected to the first port conduit 611 and the second port conduit 612.

[0101] 8 , it can be seen that the connector 464 is provided with a port connection means 4649 disposed at the port connection end 464B of the connector 464. In the example described herein, the port connection means 4649 is provided in the form of a self-closing double flap with a seal configured to provide a fluid-tight connection between the delivery port 610 and the port connection end 464B of the connector body 4641. Such a fluid-tight connection ensures that any leakage of ammonia from the first inner fluid communication conduit 4612 within the connector body 4641 will not leak through the connection between the connector body 4641 and the delivery port 610.

[0102] It will be appreciated that the fluid-tight seal between the connector body 4641 and the delivery port 610 may be provided in alternative ways in other examples not described herein.

[0103] In the example described herein, the connector body 4641 is frusto-conical. A frusto-conical connector body 4641 is preferred, but not required. If a frusto-conical connector body 4641 is provided, the delivery port 610 preferably registers with the shape and form of the connector body 4641, i.e., it is also provided in a frusto-conical form, thereby allowing for easy mating between the connector 464 and the delivery port 610 during use.

[0104] In the example described here, the connector body 4641 is configured to transfer liquid ammonia. The connector body 410 is configured such that any leaked liquid ammonia from the first inner fluid communication conduit 4612 will be received within the connector body 4641 and can be transferred to the outer fluid communication conduit 4611 of the hose 461.

[0105] Furthermore, the connector body 4641 in the example described here is configured to transport gas so that gas leaking from the second inner fluid communication conduit 4613 is received by the connector body 4641 and can be transported to the outer fluid communication conduit 4611.

[0106] An alternative safety hose 461' will now be described with reference to Figure 9. Many of the features of the previous example described with reference to Figures 7 and 8 are identical to the example described here with reference to Figure 9, and therefore like reference numerals will be used in the subsequently described examples with the addition of a prime (') to indicate like parts.

[0107] In this regard, a safety system 400' is provided that includes a safety hose 461' having a proximal end 461A', a distal end 461B', and a connector 464', the safety system 400' being arranged so that the hose 461' can be manipulated by a robot 462'. The connector 464' is connected to the distal end 461B' of the hose 461'. The hose 461' includes an outer fluid communication conduit 4611' and a single inner fluid communication conduit 4612' disposed within the outer fluid communication conduit 4611'. The single inner fluid communication conduit 4612' is configured to transport liquid ammonia (not shown) from the proximal end 461A' to the distal end 461B'. Any leakage of liquid ammonia from the first inner fluid communication conduit 4612' will not reach the environment outside the hose 461'.

[0108] The hull 600' has an integrated delivery port 610' that is registered in a manner that includes a connector 464' such that the connector 464' and the delivery port 610' mate, as previously described. The vessel may also include a fluid storage tank or other suitable container configured to store or process the supplied ammonia. In this regard, when ammonia is delivered from the safety system 400', it may be necessary to remove gas (e.g., vapor from liquid ammonia) in a safe manner. The outer fluid communication conduit 4611' is configured to transfer gas from the distal end 461B' to the proximal end 461A' such that, in use, liquid ammonia is delivered from the proximal end 461A' to the distal end 461B' in the first inner fluid communication conduit 4612', while gas can be conveyed from the distal end 461B' to the proximal end 461A' in the outer fluid communication conduit 4611'. In this manner, gas can be removed in a safe manner. As in the previously described examples, a suction device (not shown) may be provided to suck leaked gas into the outer fluid communication conduit 4611' towards the proximal end 461A'.

[0109] As in the previously described examples, the outer fluid communication conduit 4611' and the inner fluid communication conduit 4612' may be provided as flexible or rigid tubes. The inner fluid communication conduit 4612' is configured to transport liquid ammonia. Additionally, the outer fluid communication conduit 4611' is also configured to transport liquid ammonia and gas. It would be within the ability of one skilled in the art to provide suitable materials, manufacturing processes, thicknesses, etc. for the transport of liquid ammonia in the inner fluid communication conduit 4612' and liquid ammonia and gas in the outer fluid communication conduit 4611'.

[0110] Referring now to Figure 10, there is provided a kit 1000 of two safety hoses comprising a first safety hose 1461 for transporting liquid ammonia from the proximal end 1461A to the distal end 1461B of the first safety hose 1461, and a second safety hose 2461 for transporting gas from the distal end 2461B to the proximal end 2461A of the second safety hose 2461.

[0111] The first safety hose 1461 includes a first outer fluid communication conduit 14611 and a first inner fluid communication conduit 14612 disposed within the first outer fluid communication conduit 14611. The first inner fluid communication conduit 14611 is configured to transport liquid ammonia from the proximal end 1461A to the distal end 1461B of the first safety hose 1461.

[0112] The second safety hose 2461 comprises a second outer fluid communication conduit 24611 and a second inner fluid communication conduit 24612 disposed within the second outer fluid communication conduit 24611 and configured to transport gas from the distal end 2461B to the proximal end 2461A of the second safety hose 2461.

[0113] During use, leakage of liquid ammonia from the first inner fluid communication conduit 14612 will be received in the first outer fluid communication conduit 14611, and leakage of gas from the second inner fluid communication conduit 24612 will be received in the second outer fluid communication conduit 24611.

[0114] 11, a safety connector 464'' is provided for use with the first hose 1461 or the second hose 2461 of the kit 1000 shown in FIG. The safety connector 464'' will now be described with reference to the first hose 1461 of the kit 1000.

[0115] Many of the features of the safety connector 464'' are similar to the connector 464 already described. In this regard, like reference numerals are used with the addition of a double prime ('') to indicate like parts. The safety connector 464'' is configured to mate with a delivery port 610'' for the transfer of ammonia. The delivery port 610'' is provided with a single port conduit 611''. As can be seen in FIG. 11 , the single port conduit 611'' engages with the first inner fluid communication conduit 14612 of the hose 1461, thereby enabling the transfer of fluid. Although not described in detail, it will be understood that a similar connector 464''' may be provided at the distal end 2461B of the second safety hose 2461 for the transfer of gas, as already described with reference to FIG. 10.

[0116] 11 , the connector 464″ comprises a connector body 4641″ having a hose connection end 464A″ and a port connection end 464B″. The hose connection end 464A″ comprises an outer conduit connection means 4642″ configured to provide a fluid-tight connection between the hose connection end 464A″ of the connector body 4641″ and the outer fluid communication conduit 14611 of the safety hose 1461, during use.

[0117] The connector 464'' further comprises a single inner conduit fixing means 4643'' disposed within the connector body 4641'' and configured to fix the first inner fluid communication conduit 14612 to the connector body 4641'' so that, during use, the first inner fluid communication conduit 14612 can be connected to the single port conduit 611'' inside the connector body 4641''.

[0118] 11 , it can be seen that the connector 464″ is provided with a port connection means 4649″ disposed at the port connection end 464B″ of the connector 464″. In the example described here, the port connection means 4649″ is provided in the form of a self-closing double flap with a seal configured to provide a fluid-tight connection between the delivery port 620″ and the port connection end 464B″ of the connector body 4641″. Such a fluid-tight connection ensures that any leakage of liquid ammonia from the single inner fluid communication conduit 14612 in the connector body 4641″ will not leak through the connection between the connector body 4641″ and the delivery port 610″.

[0119] It will be appreciated that the fluid-tight seal between the connector body and the delivery port may be provided in alternative ways, in other examples not described herein. In the example described herein, the connector body is frusto-conical. A frusto-conical connector body is preferred, but not required. If a frusto-conical connector body is provided, the delivery port preferably registers with the shape and form of the connector body, i.e., also comprises a frusto-conical form, thereby allowing for easy mating between the connector and the delivery port during use.

[0120] In all described examples, it is preferred if the hose is connected at an angle such that, in use, any leaking fluid will flow down the hose under gravity towards the proximal end. Such an angle may be between 5° and 70° from the vertical (vertical is 0°).

[0121] Alternatively or additionally, a pump or suction device may be provided configured to transport leaked fluid in a liquid or gas state towards the proximal end. Further, the hose may be provided with one or more liquid and / or gas sensors configured to detect the presence of liquid and / or gas in the outer fluid communication conduit. Such detection may trigger an alert to an operator and / or an automatic shutdown of the pumping of liquid ammonia in the inner fluid communication conduit.

Claims

1. A system (200, 200') for safely storing ammonia below the earth's surface, comprising: an underground storage tank (300, 300') for storing liquid ammonia; a safety system (400, 400') connected to the storage tank (300, 300') to control leakage from the storage tank (300, 300') and to allow transfer of liquid ammonia into and out of the storage tank (300, 300'), a re-liquefaction system (410, 410′) configured to receive and liquefy boiling ammonia gas from the liquid ammonia in the storage tank (300, 300′) and deliver the liquefied ammonia to the storage tank (300, 300′); a recovery tank (420, 420′) configured to recover liquid ammonia leaked from the safety system (400, 400′) and deliver the leaked liquid ammonia to the storage tank (300, 300′); a scrubber (430, 430') configured to treat ammonia gas leaked from the safety system (400, 400') and deliver the treated gas to the atmosphere or the sea through a carbon filter; a water tank (440, 440') connected to the scrubber (430, 430') and configured to receive contaminated water; a pre-external cooling system (450, 450') operatively configured to pre-cool the storage tank (300, 300') and the recovery tank (420, 420'); a liquid ammonia transfer system (460, 460') configured to transfer liquid ammonia into and out of said storage tank (300, 300'); a safety system (200, 200') comprising: Equipped with the re-liquefaction system (410, 410') is configured to cool the storage tank (300, 300') and the recovery tank (420, 420') as a result of liquefaction of ammonia gas; The liquid ammonia transfer system (460, 460') comprises: an outer fluid communication conduit (4611, 4611'); a first inner fluid communication conduit (4612, 4612') disposed within the outer fluid communication conduit (4611, 4611') and configured to transport the liquid ammonia from the proximal end (461A, 461A') to the distal end (461B, 461B'); a safety hose (461, 461′) such that, in use, leakage of liquid ammonia from the first inner fluid communication conduit (4612, 4612′) is received in the outer fluid communication conduit (4611, 4611′); System (200, 200').

2. 2. The system of claim 1, wherein the storage tank is configured to withstand an internal pressure of at least 2 bar, or at least 3 bar, or at least 4 bar, or at least 5 bar.

3. The system (200, 200') of claim 1 or 2, wherein the reliquefaction and recovery tank (420, 420') is configured to withstand internal pressure.

4. The storage tank (300, 300') has a capacity of 1,000 m ３ 40,000m from ３ 10. The system (200, 200') according to any of the preceding claims, having a storage capacity of between

5. 10. The system (200, 200') according to any of the preceding claims, wherein the storage tank (300, 300') comprises walls (301, 301'), a floor (302, 302') and a roof (303, 303'), wherein the walls (301, 301') and / or the floor (302, 302') are made of concrete and the roof (303, 303') comprises a steel structure.

6. 6. The system (200, 200') of claim 5, wherein the roof (303, 303') of the storage tank (300, 300') is covered with soil.

7. The system (200, 200') according to claim 5 or 6, wherein the roof (303, 303') is welded or bolted to the walls (301, 301') and / or the floor (302, 302').

8. The system (200, 200') comprises: a reliquefaction conduit fluidly connected to the reliquefaction system (410, 410′) and the recovery tank (420, 420′); a recovery tank conduit fluidly connecting said recovery tank (420, 420') and said storage tank (300, 300'); Furthermore, the reliquefaction system (410, 410') is configured to cool the reliquefaction conduit and the recovery tank conduit as a result of liquefaction of ammonia gas; A system (200, 200') according to any of the preceding claims.

9. 9. The system of claim 8, wherein the reliquefaction system is configured to cool the reliquefaction conduit and the recovery tank conduit such that the internal temperature of the reliquefaction conduit and the recovery tank conduit is between −10 and −35° C., or approximately −20° C.

10. The water tank (440, 440') has a capacity of 100m ３ 15,000m from ３ 10. The system (200, 200') according to any of the preceding claims, having a capacity between

11. 10. The system (200, 200') according to any of the preceding claims, further comprising a chimney (431, 431') connected to said scrubber (430, 430') to allow the treated gas to be released into the atmosphere.

12. 10. The system (200, 200') according to any of the preceding claims, wherein the reliquefaction system (410, 410') is configured to cool the storage tank (300, 300') so that the internal temperature of the storage tank (300, 300') is between -5 and -50°C, or between -30 and -40°C.

13. 10. The system (200, 200') of any preceding claim, wherein the reliquefaction system (410, 410') is configured to cool the recovery tank (420, 420') so that an internal temperature of the recovery tank (420, 420') is between -10 and -35°C, or approximately -20°C.

14. 10. A system (200, 200') according to any of the preceding claims, wherein the auxiliary external cooling system (450, 450') comprises at least one freeze pipe (451, 451') located underground in sufficient proximity to the storage tank (300, 300') such that, during use, the at least one freeze pipe (451, 451') can cool the storage tank (300, 300') so that the internal temperature of the storage tank (300, 300') is between -5 and -40°C, or between -30 and -40°C.

15. 15. The system (200, 200') of claim 14, wherein the at least one freezing pipe (451, 451') is located underground within a range of 2 to 10 m, or 4 to 8 m, or approximately 5 m from the storage tank (300, 300').

16. 16. A system (200, 200') as claimed in claim 14 or 15, wherein the at least one freeze pipe (451, 451') is located underground in sufficient proximity to the recovery tank (420, 420') such that, during use, the at least one freeze pipe (451, 451') can cool the recovery tank (420, 420') so that the internal temperature of the recovery tank (420, 420') is between -10 and -35°C, or approximately -20°C.

17. 17. The system (200, 200') of claim 16, wherein the at least one freezing pipe (451, 451') is located underground within a range of 2 to 10 m, or 4 to 8 m, or approximately 5 m from the recovery tank (420, 420').

18. 16. The system (200, 200') according to claim 14 or 15, comprising a plurality of frozen pipes (451, 451') as said at least one frozen pipe (451, 451').

19. 19. The system (200, 200') according to any one of claims 14 to 18, wherein the auxiliary external cooling system (450, 450') further comprises a removable cooling unit (452, 452') configured to connect with the at least one freezing pipe (451, 451') for cooling the at least one freezing pipe (451, 451').

20. 10. The system (200, 200') according to any of the preceding claims, wherein the outer fluid communication conduit (4611, 4611') is a flexible tube.

21. 10. The system (200, 200') of any preceding claim, wherein the first inner fluid communication conduit (4612, 4612') is a flexible tube.

22. 10. The system (200, 200') of any preceding claim, wherein the outer fluid communication conduit (4611, 4611') is configured to transport liquid ammonia and / or gas.

23. A system (200, 200') as described in any of the preceding claims, wherein the outer fluid communication conduit (4611, 4611') is configured to, in use, transfer liquid to the proximal end (461A, 461A') so that, in use, any leakage of liquid ammonia from the first inner fluid communication conduit (4612, 4612') will be received within the outer fluid communication conduit (4611, 4611') and can be conveyed to the proximal end (461A, 461A').

24. A system (200, 200') as described in any of the preceding claims, wherein the outer fluid communication conduit (4611, 4611') is configured to transfer gas from the distal end (461B, 461B') to the proximal end (461A, 461A') such that, in use, liquid ammonia is passed from the proximal end (461A, 461A') to the distal end (461B, 461B') within the first inner fluid communication conduit (4612, 4612') while gas is conveyed from the distal end (461B, 461B') to the proximal end (461A, 461A').

25. a second inner fluid communication conduit (4613) disposed within the outer fluid communication conduit (4611) and configured to transfer gas from the distal end (461B) to the proximal end (461A) such that, in use, liquid ammonia is delivered from the proximal end (461A) to the distal end (461B) in the first inner fluid communication conduit (4612), while gas is conveyed from the distal end (461B) to the proximal end (461A) in the second inner fluid communication conduit (4613); A system (200, 200') as described in any of the preceding claims, wherein gas leakage from the second inner fluid communication conduit (4613) is received in the outer fluid communication conduit (4611) and can be conveyed to the proximal end (461A).

26. The liquid ammonia transfer system (460, 460') comprises a second safety hose (2461) for transferring gas from a distal end (2461B) of the second safety hose (2461) to a proximal end (2461A) of the second safety hose (2461), the second safety hose (2461) comprising: a second outer fluid communication conduit (24611); a second inner fluid communication conduit (24612) disposed within the second outer fluid communication conduit (24611) and configured to transfer gas from the distal end (2461B) to the proximal end (2461A) of the second safety hose (2461); such that, in use, leakage of gas from said second inner fluid communication conduit (24612) will be received in said second outer fluid communication conduit (24611). A system (200, 200') according to any one of claims 1 to 23.

27. and a safety connector (464) for connecting the safety hose (461) to the delivery port (610) during use for safe transfer of liquid ammonia from the inner fluid communication conduit (4612) to the delivery port (610), the connector (464) comprising: a connector body (4641) having a hose connection end (464A) and a port connection end (464B); an outer conduit connection means (4642) configured to provide a fluid-tight connection between the hose connection end (464A) of the connector body (4641) and the outer fluid communication conduit (4611) of the safety hose (461) during use; a first inner conduit fixing means (4643) disposed within the connector body (4641) and configured to fix the first inner conduit (4612) to the connector body (4641) during use so that the first inner conduit (4612) can be connected to a fluid receiving conduit (611) of the port (610) inside the connector body (4641) during use; a port connection means (4649) configured to provide a fluid-tight connection between the port connection end (464B) of the connector body (4641) and the delivery port (610) during use; Equipped with such that, in use, leakage of liquid ammonia from the first inner conduit (4612) within the connector body (4641) will be received within the connector body (4641). A system (200, 200') according to any one of claims 1 to 25.

28. 28. The system (200, 200') of claim 27, wherein the connector body (4641) is frustoconical.

29. 29. The system (200, 200') of claim 27 or 28, wherein the connector body (4641) is configured to transfer liquid ammonia.

30. the connector body (4641) is configured to transfer liquid to the hose connection end (464A) in use, such that leakage of liquid ammonia from the first inner fluid communication conduit (4612) within the connector body (4641) in use will be received by the connector body (4641) and can be conveyed to the hose connection end (464A). A system (200, 200') according to any of claims 27 to 29.

31. the connector body (4641) is configured, in use, to transfer gas from the delivery port (610) to the hose connection end (464A) such that, in use, liquid ammonia is passed through the safety connector (464) in the first inner fluid communication conduit (4612) while gas is conveyed from the delivery port (610) to the hose connection end (464A). A system (200, 200') according to any of claims 27 to 30.

32. A system (200, 200') as described in any of claims 27 to 31 when dependent on claim 25, further comprising a second inner conduit fixing means (4644) arranged within the connector body (4641) and configured to fix the second inner conduit (4613) of the safety hose (461) to the connector body (4641) in use so that the second inner conduit (4613) can be connected to the gas supply conduit (612) of the port (610) inside the connector body (4641) in use.

33. the hose connection end (464A) of the connector body (4641) is fluid-tightly connected to the outer fluid communication conduit (4611) of the safety hose (461) by the outer conduit connection means (4642); The first inner conduit (4612) is fixed to the connector body (4641) by the first inner conduit fixing means (4643). A system (200, 200') according to any of claims 27 to 32.

34. A method for safely storing ammonia underground and safely transferring the ammonia, comprising: Providing a system (200, 200') according to any of claims 1 to 33; supplying a quantity of liquid ammonia to said storage tank (300, 300'); The liquid ammonia in the storage tank (300, 300') receives and liquefies boiling ammonia gas, and the liquefied ammonia is delivered to the storage tank (300, 300'). to cool the storage tank (300, 300') and the recovery tank (420, 420') as a result of the liquefaction of ammonia gas; operating the reliquefaction system (410, 410'); transporting ammonia from the proximal end (461A) to the distal end (461B) of the hose (461) through the first inner fluid communication conduit (4612) such that any leakage of the ammonia from the first inner fluid communication conduit (4612) is received in the outer fluid communication conduit (4611); A method comprising:

35. recovering liquid ammonia leaked from the safety system (400, 400') in the recovery tank (420, 420') and delivering the leaked liquid ammonia to the storage tank (300, 300'); 35. The method of claim 34, further comprising:

36. treating the ammonia gas leaked from the safety system (400, 400') in a scrubber (430, 430') and sending the treated gas through a carbon filter into the atmosphere or into the sea; recovering contaminated water from the scrubber (430, 430') into the water tank (440, 440'); 36. The method of claim 34 or 35, further comprising:

37. 37. The method of any of claims 34 to 36, further comprising operating the auxiliary external cooling system (450, 450') to cool the storage tank (300, 300') and the recovery tank (420, 420').

38. 38. The method of any of claims 34 to 37, further comprising transferring liquid ammonia into or out of the storage tank (300, 300') using the liquid ammonia transfer system (460, 460').

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