A method and system for controlling a tank

Abstract

A method and system for controlling a tank containing a low flashpoint fuel, such as methanol, for powering a vessel is disclosed. The method comprises measuring the temperature of the tank's content and determining whether this temperature exceeds a first threshold temperature, which is below the boiling point of the content. The method further comprises ingressing water into the tank if the measured temperature exceeds the first threshold temperature. The system includes a tank, sensors for measuring temperature, conduits for ingressing water into the tank, valves for controlling the ingress of water, and a computer readable medium for performing the method. Unlocking insights from Geo-Data, the present invention further relates to improvements in sustainability and environmental developments: together we create a safe and liveable world.

Description

A METHOD AND SYSTEM FOR CONTROLLING A TANKFIELD

[0001] This disclosure relates to methods and systems for controlling a tank. More particularly, the disclosure relates to a method and system for controlling a tank containing a low flashpoint fuel for powering a vessel. Through this procedure, proactive measures are taken to maintain the safety and integrity of the tank by managing the temperature of the content in the tank, thereby mitigating risks associated with the storage and use of low flashpoint fuels on vessels. Unlocking insights from GeoData, the present invention further relates to improvements in sustainability and environmental developments: together we create a safe and liveable world.BACKGROUND

[0002] Vessels typically use fuels like heavy fuel oil (HFO) or marine gas oil (MGO) to power their engines. These fuels are typically not environmentally friendly due to the emission of noxious gases when combusted. As such, in recent years, there has been a growing interest in using more environmentally friendly fuels. Methanol, a low flashpoint fuel, has emerged as a promising alternative as it is biodegradable and produces fewer noxious gases when combusted. However, the storage of methanol fuel on marine vessels presents its own set of challenges. Methanol has approximately half the energy density of traditional MGOs, therefore a greater volume of methanol is required to achieve the same operational capability as a vessel using traditional MGO. This necessitates larger storage tanks or more frequent refuelling stops, both of which can impact the operational efficiency of the vessel.

[0003] Furthermore, due to methanol’s low flashpoint, it presents a higher risk of ignition compared to traditional fuels. To mitigate this risk, safety regulations set by the International Code of Safety for Ships using Gases or other Low-flashpoint Fuels (IGF Code) and the International Maritime Organization (IMO) require the use of cofferdams around low flashpoint fuel tanks, e.g., methanol fuel tanks. A cofferdam refers to a space or compartment built within or adjacent to a tank, which is typically an empty sealed space. The cofferdam serves to reduce the risk of heat ingress by external fire to the tank and provides a buffer zone for detecting vapour leakage from the tank. However, the installation of cofferdams requires extensive structural modifications to the vessel, including cleaning out existing tanks and adding in steelworks. These modifications are not only costly and time-consuming, but they also reduce the volume available for fuel storage. Furthermore, as fuel tanks are usually part of the hull of a vessel and are integral to the vessel's construction, this makes the conversion of an existing tank to accommodate a cofferdam design a substantial undertaking. Accordingly, there is a general and ongoing need for systems and methods for safely and more efficiently storing methanol fuel in tanks that address the above problems.SUMMARY

[0004] The present disclosure addresses the challenges associated with the storage of low flashpoint fuels, such as methanol, on marine vessels. By introducing a method and system that does not require the use of cofferdams while maintaining safety, a solution is offered that is cost effective and space efficient. Further, the disclosed methods and systems provide improved safety compared to cofferdam tank designs by actively and adaptively managing risks associated with heat ingress.

[0005] According to an aspect of the present disclosure, there is provided a method for controlling a tank. The tank contains a low flashpoint fuel for powering a vessel. The method comprises measuring a temperature of a content of the tank. This allows for real-time monitoring of the tank's temperature, such that it remains within safe limits. In some implementations, the method further comprises determining whether the measured temperature of the content exceeds a first threshold temperature. The first threshold temperature is below the boiling point of the content. This feature allows for proactive measures to be taken if the temperature of the content approaches a dangerous level. In some implementations, if the measured temperature of the content exceeds the first threshold temperature, water is ingressed into the tank. This can help rapidly cool the content of the tank, reducing the risk of a fire or explosion. Specifically, ingressing water enables the temperature of the content, e.g., low flashpoint fuel such as methanol, to be controlled (i.e., reduced), which reduces the flammability of the content. Further, the addition of water increases the flashpoint and boiling point of the content, as well as increases its heat capacity (both the specific and total heat capacity). Additionally, ingress of water enables control (reduction) of methanol vapour build up, vapour build up increases pressure which can lead to tank failure.

[0006] In some implementations, the low flashpoint fuel comprises methanol. Methanol is a more environmentally friendly fuel option, producing fewer harmful emissions when combusted. Further, methanol is biodegradable and highly miscible in water and other organic solvents. In some implementations, the low flashpoint fuel alternatively or further comprises ethanol. Ethanol advantageously has a higher flash point, higher boiling point, and higher energy density compared to methanol, and is also biodegradable.

[0007] In some implementations, the water comprises seawater. As seawater readily available, particularly in marine environments, it can advantageously be used for water ingress to provide the benefits outlined above.

[0008] In some implementations, the content of the tank comprises a mixture of low flashpoint fuel and water prior to the ingressing of water into the tank when it is determined that the measured temperature of the content exceeds the first threshold temperature. By ingressing more water into the tank, the flammability of the content can be further reduced. Meanwhile, the flashpoint, boiling point, and heat capacity can be increased.

[0009] In some implementations, the first threshold temperature is based on a composition of the content. In some implementations, the composition of the content is a ratio of low flashpoint fuel to water. By determining the first threshold temperature based on the composition of the content, this enablesingress of water to be triggered when needed as the composition of the content is linked to its physical properties (e.g., boiling point and flashpoint).

[0010] In some implementations, the method comprises determining a second threshold temperature, wherein the second threshold temperature is different to the first threshold temperature. In some implementations, the second threshold temperature is below the boiling point of the content.

[0011] In some implementations, the step of ingressing water into the tank comprises ingressing a first quantity of water into the tank. In some implementations, after ingressing the first quantity of water into the tank, a second threshold temperature is determined based on the composition of the content of the tank after ingression of the first quantity of water into the tank. In some implementations, the second threshold temperature is below the boiling point of the content after ingression of the first quantity of water into the tank and greater than the first threshold temperature. Determining a second threshold temperature based on the modified composition after ingress of water enables subsequent ingress of water is triggered when needed. In this way, a more precise control of the temperature of the content is enabled.

[0012] In some implementations, the method further comprises determining whether the measured temperature of the content exceeds the second threshold temperature. In some implementations, the method further comprises ingressing water into the tank if the measured temperature of the content exceeds the second threshold temperature. This provides a technical effect of a two-stage response to increasing temperatures within the tank, thereby further reducing the risk of ignition and risk of tank failure.

[0013] In some implementations, the quantity and / or rate at which water is ingressed into the tank is based on one or more of: the temperature of the content of the tank; the rate of temperature increase of the content of the tank; the rate of heat flow between the tank and a surrounding environment; the rate of heat flow between the content and the tank; the pressure in the tank; the volume of the content of the tank; and the composition of the content of the tank. By taking into account one or more of the aforementioned factors, precise control over the temperature of the content of the tank by determining how much and at what rate water is ingressed is enabled.

[0014] In some implementations, the method further comprises ejecting a quantity of the content of the tank. This can be a useful measure in emergency situations, helping to quickly reduce the risk of a fire or explosion. In this way, safety of the vessel and its crew is improved. The quantity of the content of the tank may be ejected actively, induced by a pump. In alternative implementations, it may be induced by a pressure build-up in the tank. In yet alternative implementations, it may be induced by gravity, or pressure from another fuel bunker. These implementations may also be combined, e.g., ejection pressure may be provided trough a combination of a pump and gravity, or a combination of pressure build-up and a pump.

[0015] In some implementations, ejecting the quantity of the content of the tank is based on determining whether the temperature of the content is at a third threshold temperature. In some implementations, ejecting a quantity of the content of the tank is further, or alternatively, based on determining whether the pressure in the tank exceeds the design or working pressure of the tank. In some implementations,ejecting a quantity of content of the tank is further, or alternatively, based on determining whether a fire is encroaching the tank, and / or whether the vessel is sinking.

[0016] In some implementations, wherein ejecting the quantity of the content of the tank is based on determining whether the temperature of the content is at a third threshold temperature, the third threshold temperature is the boiling point of the content. By ejecting the content of the tank if the measured temperature of the content is at the boiling point, the risk of a tank explosion due to the change in state (from liquid to gas) can be removed.

[0017] According to another aspect of the present disclosure, there is provided a tank system for a vessel. The tank system comprising a tank containing a low flashpoint fuel for powering a vessel, one or more sensors for measuring a temperature of the tank system, one or more conduits for ingressing water into the tank, one or more valves for controlling the ingress of water into the tank via the one or more conduits, and one or more computer readable medium that, when executed by one or more processors, cause the tank system to perform the method as described above and herein.

[0018] In some implementations, the tank does not comprise a cofferdam structure. By avoiding the use of cofferdams, this enables a reduction in the cost of modifying existing tanks, as well as increasing the available volume for fuel.

[0019] In some implementations, the vessel is a ship, ferry, tanker, workboat, tender, small cargo vessel, ro-ro, or an offshore vessel. In some implementations, the tank system can be installed on other marine vessels (e.g., submarines, deep sea equipment), or in some cases, non-marine vessels (e.g., land vessels or vehicles, air vessels or aircraft). This highlights the wide range of vessels that can benefit from the disclosed method and system.

[0020] In some implementations, a surface of the tank is part of or connected to a hull of the vessel. In some implementations, the hull is configured to be in contact or suitable for contact with water. Having a surface of the tank being part of the hull or fuselage enables heat to be effectively dissipated to the surroundings.

[0021] In some implementations, the one or more conduits are configured to be located below a waterline of the vessel, and the tank system further comprises one or more inlet ports configured to be located below the waterline and connected to the one or more conduits. Configuring the inlet ports and conduits to be located below the waterline enables passive ingress of water into the tank.

[0022] In some implementations, the one or more valves are electrically operated, and / or manually operated. By enabling the one or more valves to be controlled this way provides improved flexibility and reliability. In particular, as valves can, in addition to being electrically operated, be manually operated for independence with circuitry, they may be manually operated even if a power or communication outage occurs.

[0023] In some implementations, the tank system further comprises a pump configured to eject the content of the tank. Using a pump enables a rapid and effective means of ejecting the content in case of an emergency situation, and / or in cases where passive ejection is insufficient.

[0024] In some implementations, the tank system further comprises a ballast tank located higher than the tank. The ballast tank is configured to eject the content of the tank when fluidly connected to thetank. The ballast tank enables the content of the tank to be passively ejected, which can be particularly useful in emergency situations.

[0025] In some implementations, the tank is a repurposed ballast tank. This provides efficient use of space and infrastructure within the vessel, and can increase fuel storage capacity.

[0026] In some implementations, the tank system comprises or is connected to a release valve for releasing pressure in the tank. The release valve enables pressure within the tank to be alleviated, thereby avoiding build-up of dangerous levels of pressure in the tank.

[0027] In some implementations, the tank system comprises or is connected to a vapour return mechanism. Being connected to a vapour return system / mechanism enables vapours to be captured and returned to a shore system, avoiding their release outside the vessel (to the environment / atmosphere).

[0028] In some implementations, the tank system is comprises or is connected to a nitrogen supply. The nitrogen supply is arranged to provide a nitrogen blanket to the tank, which reduces the risk of fire and explosion. The nitrogen blanket also mitigates corrosion by reducing the presence of oxygen and moisture, extending the lifespan of the tank and its components. Additionally, the nitrogen blanket contributes to maintaining a consistent pressure within the tank, improving the safe storage and handling of low-flashpoint fuels and reducing the risk of over or under-pressurization and potential structural damage.

[0029] In some implementations, the tank or tank system comprises a plurality of tanks. This can provide additional storage capacity for the low flashpoint fuel, helping to extend the range of the vessel.BRIEF DESCRIPTION OF THE DRAWINGS

[0030] In order to describe the manner in which the above-recited and other advantages and features of the disclosure can be obtained, a more particular description of the principles briefly described above will be provided by reference to specific embodiments thereof which are illustrated in the appended drawings. Understanding that these drawings depict only exemplary implementations of the disclosure and are therefore not to be considered to be limiting of its scope, the principles herein are described and explained with additional specificity and detail by way of example to illustrate aspects of the disclosure and with reference to the accompanying drawings, in which:

[0031] Figure 1 shows a tank system for a vessel, according to the present disclosure.

[0032] Figure 2 shows a flowchart of a method for controlling a tank, according to the present disclosure.

[0033] Figure 3 shows the tank system of Figure 1 in normal operation, according to the present disclosure.

[0034] Figure 4 shows the methanol storage tank system of Figure 3 initiating water ingress, according to the present disclosure.

[0035] Figure 5 shows a methanol storage tank system of Figure 4 at a point in time after initiating water ingress, according to the present disclosure.

[0036] Figure 6 shows a methanol storage tank system of Figure 5 initiating ejection of content of the tank, according to the present disclosure.

[0037] Figure 7 shows a methanol storage tank system of Figure 6 at a point in time after initiating ejection of content of the tank, according to the present disclosure.

[0038] Figure 8 shows a block diagram of a computer system for performing the method, according to the present disclosure.

[0039] Throughout the description and the drawings, like reference numerals refer to like features.DETAILED DESCRIPTION

[0040] The following is a description of certain embodiments of the invention, given by way of example only and with reference to the drawings.

[0041] Various implementations of the disclosure are discussed in detail below. While specific implementations are discussed, it should be understood that this is done for illustration purposes only. A person skilled in the relevant art will recognize that other components and configurations may be used without parting from the spirit and scope of the disclosure. Thus, the following description and drawings are illustrative and are not to be construed as limiting. Numerous specific details are described to provide a thorough understanding of the disclosure. However, in certain instances, well-known or conventional details are not described in order to avoid obscuring the description. A reference to an implementation in the present disclosure can be a reference to the same implementation or any other implementation. Such references thus relate to at least one of the implementations herein.

[0042] The terms used in this specification generally have their ordinary meanings in the art, within the context of the disclosure, and in the specific context where each term is used. Alternative language and synonyms may be used for any one or more of the terms discussed herein, and no special significance should be placed upon whether or not a term is elaborated or discussed herein. In some cases, synonyms for certain terms are provided. A recital of one or more synonyms does not exclude the use of other synonyms. The use of examples anywhere in this specification including examples of any terms discussed herein is illustrative only and is not intended to further limit the scope and meaning of the disclosure or of any example term. Likewise, the disclosure is not limited to various implementations given in this specification. References to ranges of values or values “between” two values should be interpreted as encompassing the end points of those ranges unless otherwise specified.

[0043] Turning now to Figure 1 , the present disclosure describes methods and systems for controlling a tank 102 containing low flashpoint fuel, such as methanol, on a vessel 104. The disclosed method and system provides a solution which improves safety by mitigating risks associated with temperature increases of the low flashpoint fuel contained in the tank, which can lead to increased flammability and increased risk of the tank 102 bursting from an overpressure of gaseous vapour. This approach may be particularly advantageous in terms of cost-effectiveness, as it eliminates the substantial costs associated with modifying existing tanks to incorporate one or more cofferdam structures to meet safety regulations. Furthermore, the disclosed methods and systems provide space efficiency by maximizing the capacity of the tank 102 for fuel, by avoiding the implementation of a cofferdam design. Additionally,the disclosed methods and systems enhances safety by providing an active response to potential fire or heat ingress hazards by controlling the temperature of the content of the tank 102 by ingressing water and ejecting the content of the tank 102.

[0044] MGO fuel comprises any marine fuels that comprises distillates. Distillates are the components of crude oil that evaporate in fractional distillation, which are then condensed from the gas phase into liquid fractions. MGO fuel usually consists of a blend of various distillates. Low flashpoint fuels refer to a class of fuels characterised by their relatively low temperature (with respect to standard or ambient temperature) at which they can vaporize to form an ignitable mixture in air. In some implementations, low flashpoint fuels refer to gaseous or liquid fuel that has a flashpoint lower than a permitted threshold defined by a safety regulation or safety standard, such as the International Code of Safety for Ship Using Gases or Other Low-flashpoint Fuels (IGF Code). These fuels are particularly identified by their flashpoint, which is the minimum temperature at atmospheric pressure at which the fuel can produce enough vapour to ignite when exposed to an open flame or spark. A prominent example of such fuels is methanol. Methanol is a type of alcohol-based fuel and has a chemical formula of CH3OH. It is a colourless volatile liquid at room temperature and has a low flashpoint. Specifically, a maximum flashpoint of methanol is approximately 12°C (54°F) at atmospheric pressure.

[0045] Turning backto Figure 1 , a tank system 100 for a vessel 104, according to the present disclosure is shown. The tank system 100 for a vessel 104 may include various components that work together to manage the storage of low flashpoint fuel such as methanol or ethanol. The vessel 104 comprises a tank 102 connected to or part of a hull 106 of the vessel 104. The tank 102 is connected to a valve 108 for controlling the ingress of water into the tank 102 via conduits 110. As shown by the waterline 114, the vessel 104 is partially submerged in water, e.g., seawater 112. Also shown is an inlet valve 116 connected to the conduits 110 for ingress of seawater 112 into the tank 102. Beside the inlet valve 1 16 is an outlet valve 118 which is connected to the conduits 110 and an emergency pump 120. The emergency pump 120 is configured to eject content of the tank 102 via outlet valve 118. The tank 102 is connected to release valves 122, which releases pressure in the tank 102. A connection 124 between the tank 102 and a vapour return mechanism is also shown. The vapour return mechanism (not shown) allows vapours to be captured and returned to a shore system, thereby avoiding their release outside the vessel. Also shown is a connection 126 between the tank 102 and a nitrogen supply. The nitrogen supply (not shown) provides a nitrogen blanket to the tank 102, which reduces risk of fire, decreases corrosion, and helps main a consistent pressure in the tank 102. Also shown is a fuel transfer / supply valve 128, which is configured to control the transfer or supply of methanol in and out of the tank 102 (e.g., to the engine, for refuelling, transferred between tanks on the vessel 104). One or more sensors (not shown) are configured to measure a temperature of the content of the tank 102. A computer system (not shown) comprising one or more computer readable medium, is configured to, when executed by one or more processors, control the components in tank system 100 to perform the methods described herein.

[0046] For consistency and clarity in this disclosure, the term “content” may refer to both the low flashpoint fuel, such as methanol or ethanol, and any water that may be present or added to the tank102. That is, the use of the term “content” throughout this document encompasses mixtures of low flashpoint fuel and water, and pure flashpoint fuel with no water.

[0047] The tank 102, which is integral to the tank system 100, is configured to contain the low flashpoint fuel and is, in some implementations, connected to or part of the hull 106 of the vessel 104. The hull 106 may serve as a structural component of the vessel 104 as well as a thermal interface, aiding in the dissipation of heat from the tank 102 to the surrounding environment. In some implementations, the hull 106 is the outer hull. In Figure 1 , the tank 102 is shown to be in contact with the bottom of the hull 106, however, in some implementations, one or more surfaces of the tank 102 may be connected to or part of the hull 106 of the vessel 104 to increase heat dissipation to the surroundings. The tank 102 may comprise a cofferdam structure for additional safety. However, in some implementations, the tank 102 does not comprise a cofferdam structure. In either case, the systems and methods described herein improve the safety of the tank 102 and tank system 100. In some implementations, the tank 102 is a repurposed ballast tank or fuel bunker tank. Using a repurposed ballast tank is particularly advantageous in that it allows for the utilization of existing infrastructure on the vessel 104, thereby reducing the costs and complexities associated with building new tanks specifically for low flashpoint fuels. Further, as a ballast tank is typically used to stabilize the vessel 104 by filling it with water or emptying water from it, the modifications required to the ballast tank for it to be used as a low flashpoint fuel tank are less complex and less expensive to implement.

[0048] In some implementations, a ballast tank separate to the low flashpoint fuel tank, e.g., tank 102, is configured to passively eject the content of the tank 102 when fluidly connected to the tank 102. In this case, the ballast tank may be located higher than the tank 102 (in the vessel 104) and contains water, usually seawater 112. For example, the ballast tank may be further from the bottom of the vessel 104 than the tank 102, or the ballast tank is closer to the top of the vessel than the tank 102. In some implementations, the height of the content ofthe ballast tank and of the tank 102 are considered instead. For example, an upper surface of the content of the ballast tank may be further from the bottom of the vessel than an upper surface of the content of the tank 102. When the ballast tank is (fluidly) connected to the low flashpoint fuel tank 102, the gravitational force is leveraged to eject the content of the tank 102 by displacing the content with the water from the ballast tank. In some implementations, where the ballast tank is not located higher than the low flashpoint fuel tank 102, the content of the tank can be ejected via displacement using a pump to actively pump water from the ballast tank to the low flashpoint fuel tank 102.

[0049] The vessel 104, which may be a ship, ferry, tanker, workboat, tender, small cargo vessel, ro-ro, an offshore vessel, or any other marine vessel (e.g., submarines, deep sea equipment) can benefit from the disclosed methods and systems. In some cases, non-marine vessels (e.g., land vessels or vehicles, air vessels or aircraft) can also implement a low flashpoint fuel tank 102. The adaptability of the technology in its application underscores the potential for the disclosed methods and systems to facilitate a transition to greener fuels in various sectors.

[0050] The valve 108 controls the ingress of water into the tank 102 via conduits 110. The valve 108 may be electrically operated, manually operated, or a combination thereof, allowing for flexibility in response to varying conditions. Electrically operated controls allow for automated, precise, and rapidresponse. An electrically operated system can automatically initiate the ingress of water without the delay associated with manual intervention. On the other hand, manually operated controls provide a failsafe mechanism in the event of electrical power loss or system failure. In situations where the vessel’s infrastructure compromised, e.g., due to a fire, the ability to manually operate the valve 108 ensures that the safety measures can still be executed. Crew members can physically access the valve 108 and perform the water ingress procedure to mitigate the risk of ignition or overpressure within the tank 102.

[0051] The conduits 110 provide a pathway for water, which may be seawater 112, to enter the tank 102. In Figure 1 , the conduits 1 10 which are connected to the inlet valve 1 16 and the outlet valve 1 18 merge into a single conduit which is connected to the tank 102 via valve 108. However, the system may be alternatively configured such these conduits 110 (inlet valve conduit 404 shown in Figures 4 and 5, and outlet valve conduit 602 shown in Figures 6 and 7) do not connect together. In some implementations, more than one conduit may be used for water ingress or ejection of content of the tank 102. In some cases, as will be discussed further below, there may be more than one tank 102. Having multiple conduits 110, which optionally are independent from each other (i.e., they do not join / fluidly connect together), provides increased flexibility and control over the content in the tank 102.

[0052] The inlet valve 116 is connected to the conduits 110 and facilitates the ingress of seawater 112 into the tank 102. The inlet valve 116, like valve 108, may be designed to open automatically when the temperature of content of the tank 102 exceeds a predetermined threshold temperature and it may similarly be electrically operated, and / or manually operated. The outlet valve 118 is also connected to the conduits 110 and, in conjunction with an emergency pump 120, enables the content of the tank 102 to be ejected from the tank 102 and vessel 104. The emergency pump 120 may be powered electrically, hydraulically, or pneumatically, and is designed to rapidly remove the content of the tank 102 in emergency situations. The content of the tank 102 may be ejected using the emergency pump 120, in combination with, or in lieu of the systems described with the ballast tank. In some implementations, the one or more conduits 110 are configured to be located below a waterline 114 of the vessel 104, and the tank system 100 further comprises one or more inlet ports configured to be located below the waterline 114 and connected to the one or more conduits 110. This enables passive ingress of water into the tank 102 due to the water pressure created by the pressure head of water above the one or more conduits and the one or more inlet ports. However, in some implementations, a pump may additionally or alternatively be used to ingress water into the tank 102.

[0053] Release valves 122 are connected to the tank 102 and are responsible for releasing pressure within the tank 102. These valves 122 may be set to open at specific pressure thresholds to prevent over-pressurization, which can result from the build-up of pressure due to heat exposure or other factors. Like valve 108, release valves 122 may be electrically operated, and / or manually operated. Additionally, the release valves 122 may be utilized during the process of ingressing water into the tank 102. Specifically, as the introduction of water can increase the pressure within the tank 102, the ability to release this pressure in a controlled manner is integral to maintaining the tank’s 102 integrity. In Figure 1 , there are three release valves 122 shown, which may be independently operated. There may be a plurality of release valves 122. The release valves 122 may release vapour above and / or below the waterline 114.

[0054] The pressure in the tank 102 is linked to the temperature of the low flashpoint fuel. This is because as the temperature of the low flashpoint fuel, e.g., methanol, within the tank 102 increases, the vapour pressure also increases as more of the fuel evaporates. Further, the increased temperature loads to expansion of the vapour gas. When the fuel reaches its boiling point and begins to transition from a liquid to a gas, this phase change can lead to a rapid expansion of volume (and therefore pressure) as a gas occupies a larger volume than a liquid. However, the release valves 122, while providing a means of removing overpressure, are not designed to handle rapid and large increases in pressure. Similarly, the low flashpoint fuel tank 102 is not built to withstand the pressures created when fuel turns into a gas. As such, there is a high risk of the tank 102 exploding when the temperature of the content of the tank 102 is at, near, or exceeds its boiling point. Further, as discussed above, low flashpoint fuels are increasingly flammable at higher temperatures, which presents a further safety risk to the vessel 104 and crew.

[0055] As the temperature is linked to the pressure, the disclosed methods and systems focus on monitoring / measuring the temperature of the content, e.g., methanol, in the tank 102. If the measured temperature approaches the boiling point, the system can initiate a response to control the situation. One such response is the ingress of water into the tank 102, which serves to dilute the content, increase the mass and heat capacity, and reduce its temperature. This action helps to prevent the content from reaching its boiling point. Alternatively or additionally, in the same way that a temperature of the content, or more specifically a temperature threshold of the content can be the trigger for ingress of water or ejection of content of the tank 102, the methods and systems described herein can equally apply to pressure. That is, rather, or in addition, to measuring a temperature of a content of the tank 102, a pressure is measured. In some implementations, instead of determining whether the measured temperature of the content exceeds a first threshold temperature (second threshold temperature, etc.), it is a first threshold pressure (second threshold pressure, etc.). The first threshold pressure may be relative to (e.g., set at or below) the design pressure or working pressure of the tank 102. In some implementations, the ingress of water and / or ejection of content of the tank 102 may be based on a combination of both temperature and pressure, in which water ingress and / or ejection of content is triggered when either the temperature exceeds a temperature threshold or the pressure exceeds a pressure threshold.

[0056] The vapour return mechanism is connected to the tank 102, via a connection / conduit 124, and is configured to capture vapours generated within the tank 102, returning them to a shore system to prevent their release to the surroundings or environment. The shore system is a system which captures and store methanol vapour so it can be safely treated when the vessel returns to shore. When methanol fuel is added to the tank, methanol vapour displaced by the methanol fuel is captured by the shore system via the vapour return mechanism. In Figure 1 , the connection 124 to the vapour return mechanism (which is connected to a shore system) shares the same conduit as the release valves 122. However, like the conduits 110 connected to inlet valve 116 and outlet valve 118, the connection 124 to the vapour return mechanism may be separate to the release valves 122.

[0057] The nitrogen supply is connected to the tank 102, via a connection / conduit 126, and is configured to provide a nitrogen blanket, which is an inert atmosphere that reduces the risk of fire andexplosion by displacing oxygen. The nitrogen supply may also help in maintaining a consistent pressure within the tank 102 and preventing corrosion by reducing the presence of oxygen and moisture. In an implementation, as shown in Figure 1 , the nitrogen supply is coupled / connected to a headspace of the tank 102 via connection 126.

[0058] The fuel transfer / supply valve 128 enables the low flashpoint fuel to be transferred to the engine, out of the vessel 104, or to another tank. This connection can also be used to refuel the tank 102.

[0059] Sensors, which are not shown, are configured to measure the temperature of the content of the tank 102. These sensors may be thermocouples, resistance temperature detectors (RTDs), or other suitable temperature-sensing devices. The sensors may be placed at strategic locations proximate to and / or within the tank 102 to provide accurate temperature readings. In some implementations, if pressure is incorporated into the method and systems described herein, the sensors may further comprise sensors capable of measuring pressure.

[0060] A computer system, also not shown, comprises one or more computer-readable media that, when executed by one or more processors, control the components in the tank system 100 to perform any of the methods disclosed herein. The computer system may include software algorithms designed to process sensor data, control valves, and activate the emergency pump 120 based on predefined conditions. The computer system may also interface with the vessel’s 104 navigation and communication systems to provide alerts and updates to the crew. Alternative embodiments of the computer system may include redundant systems for increased reliability or may be integrated with other vessel control systems for centralized management. The computer system and its components are discussed in more detail with reference to Figure 8. It is noted that while the methods disclosed herein may be carried out by the computer system, they may equally be carried out by a person, such as the crew of the vessel 104. That is, a person may carry out steps of any of the methods disclosed herein alone, or in some implementations, steps may be performed by a person together with the computer system. For example, the computer system may measure the temperature of a content of the tank 102, while a person may determine whether it exceeds a first threshold temperature.

[0061] In some implementations, the tank system 100 and / or the tank 102 comprises a plurality of tanks. Each tank 102 may be configured to contain low flashpoint fuel such as methanol. The tanks may be arranged in various configurations, such as side-by-side, stacked, or distributed throughout the vessel 104 to balance weight and optimize space utilization. Each tank 102 in the plurality of tanks may be equipped with its own set of sensors, valves, conduits, and other components to independently control the temperature of the content within that specific tank 102. In some cases, the tanks may be interconnected to allow for the transfer of fuel or water between them, facilitating efficient management of the vessel’s 104 fuel reserves and ballast.

[0062] Turning to Figure 2, a method 200 for controlling a tank 102 is shown. At step 202, the method comprises measuring the temperature of a content of the tank 102. At step 204, the method further comprises determining whether the measured temperature of the content exceeds a first threshold temperature. At step 206, the method further comprises ingressing water into the tank 102 if the measured temperature of the content exceeds the first threshold temperature. In some implementations, at step 208, the method comprises determining a second threshold temperature. In someimplementations, at step 210, the method comprises ingressing water into the tank 102 if the measured temperature of content exceeds the second threshold temperature. In some implementations, at step 212, the method comprises determining whether the temperature of the content is at a third threshold temperature. In some implementations, at step 214, the method comprises ejecting the content of the tank 102 if the measured temperature is at the third threshold temperature. Each step of method 200 will now be described in more detail.

[0063] The method begins at step 202 with measuring the temperature of a content of the tank 202. In some implementations, the content of the tank 102 may be methanol. The temperature of the content may be measured using one or more sensors, which may be a thermocouple, a resistance temperature detector (RTD), or any other suitable temperature-sensing device. In some implementations, at step 202, a pressure is measured alternatively, or in addition, to measuring the temperature. The condition of the content in the tank 102 is monitored to ensure proactive measures can be taken before the content reaches a temperature that could pose a safety risk.

[0064] At step 204, the method further comprises determining whether the measured temperature of the content exceeds a first threshold temperature. The method further comprises ingressing water into the tank 102 if the measured temperature of the content exceeds the first threshold temperature 206. The water may be seawater 112, which can be ingressed into the tank 102 through conduits 110 (specifically inlet valve conduit 404 in Figures 4 and 5). The inlet valve 116 or valve 108 may be electrically operated, manually operated, or a combination thereof. In some implementations, as discussed earlier, the tank 102 may already comprise a mixture of low flashpoint fuel and water prior to any or additional ingress of water.

[0065] In some implementations, at step 208, the method further comprises determining a second threshold temperature. In some implementations, the second threshold temperature is different to the first threshold temperature. In some implementations, the second threshold temperature is determined after ingress of a first quantity of water into the tank. In some implementations, the second threshold temperature is determined based on the composition of the content of the tank after ingression of the first quantity of water into the tank. In some implementations, the second threshold temperature like the first threshold temperature may be below the boiling point of the content after ingress of a first quantity of water into the tank 102 (or regardless of ingress of a first quantity of water into the tank 102). In some implementations, the second threshold temperature after ingress of a first quantity of water into the tank is greater than the first threshold temperature (or regardless of ingress of a first quantity of water into the tank 102).

[0066] In some implementations, at step 210, the method further comprises ingressing water into the tank 102 if the measured temperature exceeds the second threshold temperature 210. As will be apparent, there may be more than a first threshold temperature and a second threshold temperature for triggering water ingress. That is, there may be a plurality of threshold temperatures, and a plurality of instances of water ingress (until the tank is full).

[0067] In some implementations, the first threshold temperature or any other threshold temperature (second, third, etc.) is based on the composition of the content of the tank 102. The composition of the content plays a substantial role in determining its physical properties, such as the boiling point,flashpoint, and specific heat capacity. By determining and setting a threshold temperature based on the composition of the content, ingress of water and / or ejection of content of the tank 102 can be triggered when needed. In some implementations, the threshold temperature is a fixed value, e.g., 45 °C, which does not change regardless of changes in the composition of the content in the tank 102. This fixed value could be predetermined based on safety standards, operational parameters, or empirical data that indicates a safe operating temperature for the tank 102 or content in the tank 102. However, in other implementations, the threshold temperature can vary based on the composition, such that it is set relative to physical properties of the content. For example, the first threshold temperature may be offset to be 20 °C below the boiling point of the content. If the tank 102 contains only methanol and no water, then using the boiling point of methanol which is 66 °C, the first threshold temperature is 46 °C. In another example, the tank 102 contains a 20% / 80% mixture of methanol to water by volume percent (e.g., after ingress of water). In this case, the boiling point of the composition is 86 °C. Therefore, the first threshold temperature (could also been seen as the second threshold temperature as it has changed) becomes 66 °C. In some implementations, as water in ingressed and the content becomes less flammable, the offset below the boiling point may be decreased. For example, the offset may be set to be 15 °C instead for a 20% / 80% methanol water mixture, resulting in a threshold temperature of 71 °C (a 15 °C negative offset from the boiling point of 86 °C). The threshold temperature can also be based on physical properties other than the boiling point, such as the flashpoint.

[0068] In some implementations, the offset may be decreasing as the composition of the tank 102 changes (e.g., as water is ingressed) as described in the aforementioned example. In this implementation, a decreasing offset can lead to a decreasing "buffer" for threshold temperatures. A smaller buffer may be adequate if the composition of content is less susceptible to temperature changes from an increase in heat capacity, and less susceptible to ignition from a decrease in flammability. Accordingly, like the temperature threshold, the magnitude of the offset can be set relative to the composition or physical property of the content. In some implementations, the magnitude of the offset can be decreasing as the composition becomes less flammable (e.g., as volume percent of water increases) and the heat capacity increases (due to ingress of water).

[0069] However, in some implementations, the magnitude of the offset can be increasing as the composition of the content changes. The magnitude of the offset may be increasing when the volume of content in the tank 102 decreases (e.g., when the content is transferred to the engine, out of the vessel 104, or to another tank 102 using the methanol transfer / supply valve 128). This is because a decrease in content leads to a lower heat capacity and more volume of gas in the tank, making the content more susceptible to pressure increase from heat ingress. Consequently, the increase in the magnitude of the offset provides an increasing / larger “buffers” for threshold temperatures, which improves safety.

[0070] In some implementations, the offset for threshold temperatures may be constant even if the composition of the tank 102 changes. For example, it can be fixed to 20 °C below the boiling point of the content, 25 °C below the boiling point, 30 °C below the boiling point, etc. This has the advantage of providing a constant "buffer" to the boiling point, enabling the system to respond to sudden heat ingressor non-uniform heat ingress (the temperature of content at one location in the tank 102 may be higher than the content in other locations).

[0071] As the boiling point of a substance can vary based on pressure, the pressure may additionally be measured and used in combination with composition of the content to determine any of the threshold temperatures discussed herein.

[0072] The quantity and / or rate at which the water is ingressed into the tank 102 may be based on one or more of the temperature of the content of the tank 102, the rate of temperature increase of the content of the tank 102, the rate of heat flow (i.e., temperature gradient) between the tank 102 and a surrounding environment, the rate of heat flow (i.e., temperature gradient) between the content and the tank 102, the pressure in the tank 102, the volume of the content of the tank 102, and the composition of the content of the tank 102. In some implementations, the volume of the content and the composition of the content of the tank 102 can be used to determine the heat capacity of the content. The heat capacity in combination with the temperature of the content of the tank 102 can be used to determine the quantity of water to ingress in order to bring the content to a target temperature. The target temperature may be the threshold temperature which triggered the ingress of water.

[0073] Specifically, if rate of heat flow from the content to the surroundings via the tank 102 is high, the rate and / or quantity of water can be decreased, as the tank 102 is unlikely to increase in temperature as rapidly. On the other hand, if the rate of heat flow from the content to the surroundings via tank 102 is low, then the rate and / or quantity of water can be increased as there is less heat dissipated. In some implementations, the rate of change of the rate of heat flow between the content and the tank 102 and / or between the tank 102 and a surrounding environment can be alternatively, or additionally, incorporated into the determination of the quantity and / or rate of water ingressed. In some implementations, the pressure in the tank 102 is alternatively, or additionally, taken into account for the quantity and / or rate of water ingressed. If the pressure within the tank 102 is high, the rate and / or quantity of water ingress can be decreased to avoid sharply increasing the pressure within the tank 102. In some implementations, if the volume of content in the tank 102 is high, i.e., the tank 102 is full or almost full, the quantity rate of water ingressed can be decreased to avoid overfilling the tank 102. To ensure that the threshold temperature (first, second, third, etc.) used to trigger water ingress or ejection of content of the tank corresponds to the current state of the content of the tank 102, the threshold temperatures may be periodically updated and / or updated when one or more of the aforementioned factors changes. In this way, precise control over the temperature is enabled.

[0074] Turning to step 212, in some implementations, the method comprises ejecting a quantity of the content of the tank 102. The determination for ejecting a quantity of the content of the tank 102 is based on determining whether: the temperature of the content is at a third threshold temperature, wherein the third threshold temperature is the boiling point of the content; the pressure in the tank 102 is at the design or working pressure of the tank 102; a fire is encroaching the tank 102; and / or the vessel 104 is sinking. At the design or working pressure of the tank 102, there is a high risk of the tank 102 failing. In some implementations, ejecting a quantity of the content of the tank 102 comprises ejecting the entirety of the content of the tank 102. In some implementations, the method comprises specifically ejecting the content of the tank 102 based on determining that the measured temperature of content is at the thirdthreshold temperature 214. Ejecting the content of the tank 102 is a measure of last resort, employed when, the temperature of the content reaches a third threshold temperature, which is typically set at or near the boiling point of the content. At this juncture, the risk of ignition or explosion becomes imminent due to the rapid vaporization from the change of state from liquid to gas. By ejecting the content, pressure is alleviated and flammable fuel is removed from the vessel 104, which improves the safety for the crew and vessel 104. The design pressure refers to the highest level of pressure that the tank was designed to be exposed to during normal operating conditions. The working pressure, i.e., maximum allowable working pressure (MAWP), is the highest level of pressure the tank can physically withstand, and is typically lower than the design pressure. Similarly, when a fire is encroaching the tank 102, i.e., a fire is detected to be in close proximity to the tank 102, detected to be spreading to the tank, or detected to be in the same room as the tank 102, and in any of these cases it cannot be extinguished (e.g., via a sprinkler system), ejection of the content of the tank 102 can effectively avoid pressure build up in the tank 102 due to heat ingress, and / or the risk of the fuel igniting. Specifically, the fire may be detected via cameras (e.g., optical, thermal), temperature sensors, smoke detectors, etc., proximate to the tank 102 and connected to the computer system which can trigger the ejecting of content of the tank. Finally, the ejection of content of the tank 102 can also be triggered if it is determined that the vessel 104 is sinking, which can increase the buoyancy of the vessel 104, thereby increasing the time available for the crew to evacuate. The determination of whether the vessel the sinking can be determined using water sensors, cameras, or determined by the crew. Accordingly, the ejection of content in an emergency situation provides a robust safety measure that further improves safety. In some implementations, the ejecting of content of the tank 102 may be performed without ingressing any water into the tank 102, i.e., the method steps 202 to 210 in method 200 may be skipped.

[0075] As discussed, similar to the determination of the first threshold temperature and the second threshold temperature for water ingress, the third threshold temperature may be set at or near (relative to) the boiling point of the content. In some implementations, the third threshold temperature may be set at an offset relative to the boiling point of the content of the tank 102 to provide a "buffer" before triggering ejection of the content of the tank. The “buffer” enables the tank system 100 to respond to sudden or non-uniform heat ingress (e.g., a fire on one side of the tank 102). As such, setting a third threshold temperature to be at a negative offset from the boiling point, which creates a buffer, enables safety to be improved. The negative offset, i.e. buffer, for the third threshold temperature may be, e.g., 5 °C below the boiling point of the content. As the boiling point of a substance can vary based on pressure, the pressure may be measured and taken into account. The pressure may also be used as a triggering condition for the ejection of content in combination with the determination that the temperature of the content is at or exceeds the third threshold temperature. Like the first threshold temperature and the second threshold temperature, the third threshold temperature may be periodically updated and / or updated when any of the one or more of the factors previously mentioned for controlling quantity and / or rate of water ingress changes.

[0076] In some implementations, instead of ingressing water in the tank 102, methanol fuel may be ingressed instead (e.g., from another tank 102 on the vessel 104). This may be the case when there is no water available, or if it is undesirable to mix the methanol fuel with water (such that it can still be usedas fuel for the vessel 104). By increasing the quantity of methanol in the tank 102, the surface area of the tank 102 that the methanol in contact with increases (as it does when water is ingressed), which enables heat to be effectively dissipated. Further, an increase in methanol increases the heat capacity making it less susceptible to temperature increases (as more energy is needed to increase its temperature). Finally, increasing the quantity of methanol in the tank 102 reduces the available volume for methanol vapour to accumulate, which poses the greatest risk of ignition and overpressure as a gas expands more than a liquid. Accordingly, it can be advantageous to keep the tank 102 as full as possible. In scenarios where it is not feasible to keep the tank 102 full of methanol fuel, ingressing water into the tank 102 can serve as an alternative method to increase the thermal mass, displace vapours, reduce the temperature, reduce its flammability, and increase its flashpoints and boiling points. In an emergency situation, the methanol fuel can also be ejected from the tank 102 as discussed herein.

[0077] Referring to Figure 3, the tank system 100 of Figure 1 in normal operation is shown. During normal operation, the release valves 122, valve 108, inlet valve 116, and outlet valve 118 are closed, and the connection 124 to the vapour return mechanism, connection 126 to the nitrogen supply, and the fuel transfer / supply valve 128 is open. As shown in tank 102, the tank 102 is partially filled with methanol 302. However, in some implementations, the tank 102 may comprise any low flashpoint fuel. A summary of states of the tank 102 and content 302 of the tank 102 are provided in the description of each of Figures 3 to 7 below. These states illustrate how the composition of the content 302 and physical properties of the content 302 changes as steps of method 200 are performed. “Volume of content” indicates the volume percentage of the tank 102 which is occupied by the content 302, i.e., presently purely methanol fuel. “Composition of content” (methanol / water) shows the ratio of methanol to water by volume percent of the methanol fuel 302, which is currently 100% methanol to 0% water. “Flashpoint of content” indicates the flashpoint of the content 302, i.e., currently pure methanol in tank 102, which is 12 °C. “Boiling point of content” indicates the boiling point of the content 302, i.e., presently pure methanol in tank 102, which is 66 °C. “Temperature of content” indicates the temperature of the content 302, which is 30 °C. In summary, the state of the tank 102 and the content 302 of the tank 102 in Figure 3 are as follows:Volume of content: 20%Composition of content (methanol I water): 100% 1 0%Flash point of content: 12 °CBoiling point of content: 66 °CTemperature of content: 30 °C

[0078] Referring to Figure 4, the tank system 100 of Figure 3 initiating water ingress is shown as an example implementation of step 206 of method 200. As an example implementation of step 204, the temperature of the content 302, which has increased to 42 °C due to heat ingress, is determined to have exceeded a first threshold temperature of 41 °C. In this example, the first threshold temperature is set relative to the boiling point of the content 302, and is specifically 25 °C below the boiling point. As the boiling point of the content is currently 66 °C (for 100% methanol), the first threshold temperature is 41 °C (25 °C subtracted from the boiling point of 66 °C). To facilitate water ingress intothe tank 102, the inlet valve 116, valve 108, and the release valves 122 are opened. The connection 124 to the vapour return mechanism remains open. The connection 126 to the nitrogen supply and the fuel transfer / supply valve 128 is closed. As an example implementation of water ingress in step 206, seawater 112 is ingressed from inlet valve 116 through inlet valve conduit 404 and valve 108 into tank 102. In this example, the seawater 112 is ingressed passively as inlet valve conduit 404 and inlet valve 116 are configured to be located below the waterline 114. As shown by the arrows in the tank 102, the ingress of seawater 112 will result in an increase in the volume of content 302 in the tank 102. To alleviate the pressure increase in the tank 102 caused by the ingress of water, release valve 402 of the release valves 122 is opened to allow gas to escape the vessel 104 above the waterline 114. In some implementations, the release valves 122 may be configured to release pressure below the waterline 114, or configured to simultaneously release pressure both above and below the waterline 114. In summary, the state of the tank 102 and the content 302 of the tank 102 in Figure 4 are as follows: Volume of content: 20%Composition of content (methanol I water): 100% 10% Flash point of content: 12 °CBoiling point of content: 66 °CTemperature of content: 42 °CFirst temperature threshold: 41 °C

[0079] Referring to Figure 5, the tank system 100 of Figure 4 at a point in time after initiating (during) ingress of water is shown. At this point in time, the volume of content 302 is at 90%, indicating that the tank 102 is 90% full. The composition of content 302 is now 20% methanol to 80% water. Due to the change in composition of the content 302 of the tank 102, the flashpoint of the content 302 is increased from 12 °C to 44 °C. Further, the boiling point is increased from 66 °C to 86 °C. The temperature of the content 302 is increased from 45 °C to 63 °C despite the ingress of seawater 112 due to ingress of heat. At this point in time, ingress of seawater 112 will continue as the temperature of the content 302 still exceeds the first temperature threshold. This is because the first temperature threshold is now 61 °C due to the change in composition of the content 302, which increased the boiling point of the content 302 to 86 °C (25 °C subtracted from the boiling point of 86 °C is 61 °C). The updated first temperature threshold of 61 °C can be seen as a second temperature threshold. However, as discussed herein, in some implementations, the second temperature threshold may be independent from the first temperature threshold. For example, as an example implementation of step 208 of method 200, the second temperature threshold may be set relative to the boiling point of the content 302, e.g., to be 20 °C below the boiling point. As an example implementation of step 210, if the temperature of the content 302 exceeds the second threshold temperature, seawater 112 may be further ingressed into tank 102. In summary, the state of the tank 102 and the content 302 of the tank 102 in Figure 5 are as follows:Volume of content: 90%Composition of content (methanol / water): 20% / 80%Flash point of content: 44 °CBoiling point of content: 86 °CTemperature of content: 63 °CFirst temperature threshold: 61 °C

[0080] Referring to Figure 6, the tank system 100 of Figure 5 initiating ejection of content 302 of the tank 102 is shown as an example implementation of step 214 of method 200. At this point in time, the tank 102 is 100% full of a 22% methanol to 78% water mixture. Due to the change in composition, the flashpoint and boiling point has increased further to 46 °C and 89 °C respectively. As the tank 102 is full, water ingress is no longer possible, however, the temperature of the content 302 has continued to rise to 74 °C due to heat ingress. In this example, the third temperature threshold is set relative to the boiling point and is specifically 15 °C below the boiling point of the content 302. As an example, implementation of steps 212 and 214, if the temperature of the content 302 is determined to be at the third threshold temperature (step 212), the content 302 of the tank 102 is ejected by the tank system 100 to remove the fire hazard (step 214). As the temperature of the content 302 is 74 °C, which is equal to the third threshold temperature of 74 °C (15 °C subtracted from the boiling point of 89 °C is 74 °C), the tank system 100 begins ejecting the content 302 of the tank 102. As shown in Figure 6, the release valve 122, 402 is closed, the connection 124 to the vapour return mechanism is closed, and the inlet valve 116 is closed. The connection 126 to the nitrogen supply is opened. In some implementations, the connection 126 to the nitrogen supply is opened when the ejection of content is initiated or when the emergency pump is turned on. This advantageously fills the empty space in the tank with nitrogen, which forms a barrier to the development of methanol vapour and reduces the flammability of methanol vapour. In some implementations, the connection 126 to the nitrogen supply may be turned on earlier, such as during water ingress (e.g., in the example of Figure 5) or after stopping water ingress. The mixing of nitrogen with the content in the tank 102 can enable further reduction in the flammability of the content. Turning back to Figure 6, the fuel transfer / supply valve 128 remains closed, the emergency pump 120 is turned on and the outlet valve 118 is opened. The valve 108 remains open. In summary, the state of the tank 102 and the content 302 of the tank 102 inFigure 6 are as follows:Volume of content: 100%Composition of content (methanol I water): 18% I 82%Flash point of content: 46 °CBoiling point of content: 89 °CTemperature of content: 69 °CFirst temperature threshold: 64 °CThird temperature threshold: 69 °C

[0081] Referring to Figure 7, the tank system 100 of Figure 6 at a point in time after (during) ejection of the content 302 of the tank 102 is shown. The content 302 of the tank 102 is actively being ejected from the tank 102 and from the vessel 104 via outlet valve conduit 602 and outlet valve 118 using theemergency pump 120. The volume of content 302 in the tank 102 is now reduced to 5%. The composition, flashpoint, and boiling point of the content 302 remains the same, as there is no change in the composition of the content 302. The temperature of content 302 in the tank 102, however, decreases in temperature due to the decrease in pressure in the tank 102 from the ejection of content. To evacuate the any remaining methanol vapour in the tank 102, the connection 124 to the vapour return mechanism is opened. To reduce the risk of ignition of the methanol vapour, the connection 126 to the nitrogen supply remains open. In summary, the state of the tank 102 and the content 302 of the tank 102 in Figure 7 are as follows:Volume of content: 5%Composition of content (methanol I water): 18% I 82%Flash point of content: 46 °CBoiling point of content: 89 °CTemperature of content: 25 °C

[0082] Figure 8 shows a block diagram of one implementation of a computing device 800 within which a set of instructions, for causing the computing device to perform any one or more of the methodologies discussed herein, may be executed. In alternative implementations, the computing device may be connected (e.g., networked) to other machines in a Local Area Network (LAN), an intranet, an extranet, or the Internet. The computing device may operate in the capacity of a server or a client machine in a client-server network environment, or as a peer machine in a peer-to-peer (or distributed) network environment. The computing device may be a personal computer (PC), a tablet computer, a set-top box (STB), a Personal Digital Assistant (PDA), a cellular telephone, a web appliance, a server, a network router, switch or bridge, or any machine capable of executing a set of instructions (sequential or otherwise) that specify actions to be taken by that machine.

[0083] Further, while only a single computing device is illustrated, the term “computing device” shall also be taken to include any collection of machines (e.g., computers) that individually or jointly execute a set (or multiple sets) of instructions to perform any one or more of the methodologies discussed herein. Each computing device may have the structure shown in Fig. 8. Alternatively, a plurality of processors within a single computing device, such as computing device 800, can perform the independent computations.

[0084] The example computing device 800 includes a processor 802, a main memory 804 (e.g., readonly memory (ROM), flash memory, dynamic random access memory (DRAM) such as synchronous DRAM (SDRAM) or Rambus DRAM (RDRAM), etc.), a static memory 806 (e.g., flash memory, static random access memory (SRAM), etc.), and a secondary memory (e.g., a data storage device 818), which communicate with each other via a bus 830.

[0085] Processor 802 represents one or more general-purpose processors such as a microprocessor, central processing unit, or the like. More particularly, the processor 802 may be a complex instruction set computing (CISC) microprocessor, reduced instruction set computing (RISC) microprocessor, very long instruction word (VLIW) microprocessor, processor implementing other instruction sets, or processors implementing a combination of instruction sets. Processor 802 may also be one or morespecial-purpose processors such as an application specific integrated circuit (ASIC), a field programmable gate array (FPGA), a digital signal processor (DSP), network processor, or the like. Processor 802 is configured to execute the processing logic (instructions 822) for performing the operations and steps discussed herein.

[0086] The computing device 800 may further include a network interface device 808. The computing device 800 also may include a video display unit 810 (e.g., a liquid crystal display (LCD) or a cathode ray tube (CRT)), an alphanumeric input device 812 (e.g., a keyboard or touchscreen), a cursor control device 814 (e.g., a mouse or touchscreen), and an audio device 816 (e.g., a speaker).

[0087] It will be apparent that some features of computer device 800 shown in Fig. 8 may be absent. For example, one or more computing devices 800 may have no need for display device 810 (or any associated adapters). This may be the case, for example, for particular server-side computer apparatuses 800 which are used only for their processing capabilities and do not need to display information to users. Similarly, user input device 812 may not be required. In its simplest form, computing device 800 comprises processor 802 and memory 804.

[0088] The data storage device 818 may include one or more machine-readable storage media (or more specifically one or more non-transitory computer-readable storage media) 828 on which is stored one or more sets of instructions 822 embodying any one or more of the methodologies or functions described herein. The instructions 822 may also reside, completely or at least partially, within the main memory 804 and / or within the processor 802 during execution thereof by the computer system 800, the main memory 804 and the processor 802 also constituting computer-readable storage media.

[0089] The various methods described above may be implemented by a computer program. The computer program may include computer code arranged to instruct a computer to perform the functions of one or more of the various methods described above. The computer program and / or the code for performing such methods may be provided to an apparatus, such as a computer, on one or more computer readable media or, more generally, a computer program product. The computer readable media may be transitory or non-transitory. The one or more computer readable media could be, for example, an electronic, magnetic, optical, electromagnetic, infrared, or semiconductor system, or a propagation medium for data transmission, for example for downloading the code over the Internet. Alternatively, the one or more computer readable media could take the form of one or more physical computer readable media such as semiconductor or solid state memory, magnetic tape, a removable computer diskette, a random access memory (RAM), a read-only memory (ROM), a rigid magnetic disc, and an optical disk, such as a CD-ROM, CD-R / W or DVD.

[0090] In an implementation, the modules, components and other features described herein can be implemented as discrete components or integrated in the functionality of hardware components such as ASICS, FPGAs, DSPs or similar devices.

[0091] A “hardware component” is a tangible (e.g., non-transitory) physical component (e.g., a set of one or more processors) capable of performing certain operations and may be configured or arranged in a certain physical manner. A hardware component may include dedicated circuitry or logic that is permanently configured to perform certain operations. A hardware component may be or include a special-purpose processor, such as a field programmable gate array (FPGA) or an ASIC. A hardwarecomponent may also include programmable logic or circuitry that is temporarily configured by software to perform certain operations.

[0092] Accordingly, the phrase “hardware component” should be understood to encompass a tangible entity that may be physically constructed, permanently configured (e.g., hardwired), or temporarily configured (e.g., programmed) to operate in a certain manner or to perform certain operations described herein.

[0093] In addition, the modules and components can be implemented as firmware or functional circuitry within hardware devices. Further, the modules and components can be implemented in any combination of hardware devices and software components, or only in software (e.g., code stored or otherwise embodied in a machine-readable medium or in a transmission medium).

[0094] It is to be understood that the above description is intended to be illustrative, and not restrictive. Many other implementations will be apparent to those of skill in the art upon reading and understanding the above description. Although the present disclosure has been described with reference to specific example implementations, it will be recognized that the disclosure is not limited to the implementations described but can be practiced with modification and alteration within the spirit and scope of the appended claims. Accordingly, the specification and drawings are to be regarded in an illustrative sense rather than a restrictive sense. The scope of the disclosure should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled.

[0095] While at least one exemplary embodiment has been presented in the foregoing detailed description, it should be appreciated that a vast number of variations exist, only some of which have been mentioned above. It should also be appreciated that the exemplary embodiment or exemplary embodiments are only examples, and are not intended to limit the scope, applicability, or configuration of the disclosure in any way. Rather, the foregoing detailed description will provide those skilled in the art with a convenient road map for implementing the exemplary embodiment or exemplary embodiments. It should be understood that various changes can be made in the function and arrangement of elements without departing from the scope of the disclosure as set forth in the appended claims and the legal equivalents thereof.

Claims

CLAIMS1 . A method for controlling a tank, the tank containing a low flashpoint fuel for powering a vessel, the method comprising: measuring a temperature of a content of the tank; determining whether the measured temperature of the content exceeds a first threshold temperature, wherein the first threshold temperature is below the boiling point of the content; and if the measured temperature of the content exceeds the first threshold temperature, ingressing water into the tank.

2. The method of claim 1 , wherein the low flashpoint fuel comprises methanol.

3. The method of claim 1 or claim 2, wherein the first threshold temperature is based on a composition of the content.

4. The method of any of claims 1 to 3, wherein the step of ingressing water into the tank comprises ingressing a first quantity of water into the tank, the method further comprising: after ingressing the first quantity of water into the tank, determining a second threshold temperature based on the composition of the content of the tank after ingression of the first quantity of water into the tank.

5. The method of claim 4, further comprising: determining whether the measured temperature of the content exceeds the second threshold temperature; and if the measured temperature of the content exceeds the second threshold temperature, ingressing water into the tank.

6. The method of any of claims 1 to 5, wherein the quantity and / or rate at which the water is ingressed into the tank is based on one or more of: the temperature of the content of the tank; the rate of temperature increase of the content of the tank; the rate of heat flow between the tank and a surrounding environment;the rate of heat flow between the content and the tank; the pressure in the tank; the volume of the content of the tank; and the composition of the content of the tank.

7. The method of any of claims 1 to 6, wherein the method further comprises ejecting a quantity of the content of the tank.

8. The method of claim 7, wherein ejecting the quantity of the content of the tank is based on determining whether: the temperature of the content is at a third threshold temperature; the pressure in the tank is at the design pressure of the tank; a fire is encroaching the tank; or the vessel is sinking.

9. A tank system for a vessel, comprising: a tank containing a low flashpoint fuel for powering a vessel; one or more sensors for measuring a temperature of the tank system; one or more conduits for ingressing water into the tank; one or more valves for controlling the ingress of water into the tank via the one or more conduits; and one or more computer readable medium that, when executed by one or more processors, cause the tank system to perform the method of any preceding claim.

10. The tank system of claim 9, wherein the tank does not comprise a cofferdam structure.

11. The tank system of claim 9 or claim 10, wherein a surface of the tank is part of a hull of the vessel.

12. The tank system of any of claims 9 to 11 , wherein the one or more conduits are configured to be located below a waterline of the vessel, and the tank system further comprises one or more inlet ports configured to be located below the waterline and connected to the one or more conduits.

13. The tank system of any of claims 9 to 12, further comprising a pump configured to eject the content of the tank.

14. The tank system of any of claims 9 to 13, further comprising a ballast tank, the ballast tank located higher than the tank and configured to eject the content of the tank when fluidly connected to the tank.

15. The tank system of any of claims 9 to 14, wherein the tank comprises a plurality of tanks.

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