Fuel supply system and fuel recovery method using same

Abstract

A fuel supply system according to the present invention may comprise: a fuel supply line for supplying fuel from a fuel tank to an engine; a purging gas supply line connected to the fuel supply line so as to supply purging gas when the supply of fuel is stopped; a separator for receiving and storing unused fuel and the purging gas from the engine; a first fuel recovery line for primarily recovering, into the separator, the unused fuel and the purging gas from the engine; a second fuel recovery line for secondarily recovering, into the fuel tank, the unused fuel and the purging gas from the engine; a gas recovery line for joining, to the second fuel recovery line, gaseous fuel and the purging gas from the separator; and a liquid recovery line for joining, to the fuel supply line, liquid fuel from the separator.

Description

Fuel supply system and fuel recovery method using the same

[0001] Cross-citation with related applications

[0002] This application claims the benefit of priority to Korean Patent Application No. 10-2024-0096345, filed July 22, 2024, Korean Patent Application No. 10-2024-0198954, filed December 27, 2024, Korean Patent Application No. 10-2025-0028179, filed March 5, 2025, Korean Patent Application No. 10-2025-0050035, filed April 17, 2025, and Korean Patent Application No. 10-2025-0050239, filed April 17, 2025, the entire contents of which are incorporated herein by reference.

[0003] The present invention relates to a purging system for a ship, and more particularly, to a purging system for a ship capable of reducing the concentration of liquefied gas in a gaseous state vented from a separator.

[0004] Meanwhile, the present invention relates to a evaporated gas re-liquefaction system.

[0005] Meanwhile, the present invention relates to a fuel supply system and a fuel recovery method using the same.

[0006] As regulations on ships become more stringent, the fuel used for ships is shifting from conventional heavy oil to environmentally friendly fuels such as LNG, ammonia, methanol, and hydrogen.

[0007] For example, when ammonia is used as a fuel, due to the toxicity of the fuel, when the fuel supply to the engine is interrupted, the ammonia fuel inside the engine or fuel supply system must be sent to a vent gas treatment system for treatment and then discharged.

[0008] To this end, the purging gas supplied first is transferred to a separator along with the ammonia fuel remaining in the engine and fuel supply pipes. The liquid and gaseous ammonia are separated in the separator, and the gaseous ammonia is sent to a vent gas treatment system for processing and discharge. Furthermore, the purging gas supplied secondarily, along with the gaseous ammonia remaining in the engine and fuel supply pipes, is transferred to a knockout drum, where the gaseous ammonia is also sent to the vent gas treatment system for processing and discharge.

[0009] These vessel-based purging systems required increased vent gas treatment system capacity to handle the ammonia gas sent to the system. Consequently, increased vent gas treatment system capacity presented challenges such as space constraints and increased energy consumption.

[0010] Meanwhile, nitrogen oxides (NO) contained in exhaust gases emitted from ships have been recently reduced by international agreements. x ), sulfur oxides (SO x ), carbon dioxide (CO2), and other emissions are being regulated, and these regulations are being strengthened every year. Existing fossil fuels (mainly bunker C oil, diesel, etc.) emit large amounts of carbon when burned, so there is a growing demand for eco-friendly ships that generate power using low-carbon or decarbonized fuels.

[0011] Recently, ammonia (NH3) has been attracting attention as an alternative fuel to reduce carbon emissions. Chemically, ammonia is carbon-free and does not emit carbon dioxide (CO2) when burned.

[0012] Because ammonia occupies a very large volume in its gaseous state, it is typically stored as a liquid. To achieve this, ammonia is typically liquefied at temperatures below -30°C and stored in a storage tank. However, the storage tank continuously absorbs external heat, vaporizing the ammonia and generating ammonia boil-off gas (BOG).

[0013] Therefore, there is a need to re-liquefy the ammonia vapor generated within the storage tank and store it back in the tank. One re-liquefaction method is to use seawater. However, this requires compressing the ammonia vapor to high pressure, which consumes energy. Therefore, there is a need to develop a re-liquefaction system capable of efficiently re-liquefying ammonia vapor.

[0014] Meanwhile, ammonia is a substance that requires care when handling, as it can have a fatal effect on the lives of crew members if it enters the interior of a ship at a concentration exceeding a certain level due to its toxicity.

[0015] Therefore, ammonia cannot be directly discharged into or out of the vessel, requiring a separate treatment system to handle it. Typically, these treatment systems are equipped with large-capacity buffer tanks to accommodate gaseous ammonia and purging gas during ammonia purging, which increases the volume of the treatment system.

[0016] The present invention is intended to solve the problems of the prior art discussed above, and to provide a purging system for a ship capable of reducing the concentration of liquefied gas in a gaseous state vented from a separator.

[0017] Meanwhile, the present invention seeks to provide an ammonia evaporation gas re-liquefaction system capable of improving re-liquefaction efficiency.

[0018] Meanwhile, the present invention is intended to solve the problems of the prior art as described above, and proposes a fuel supply system and a fuel recovery method using the same, which can reduce the volume occupied by the entire system by utilizing a fuel tank as a buffer tank that receives gaseous ammonia and purging gas.

[0019] In addition, the present invention proposes a fuel supply system and a fuel recovery method using the same that can effectively process ammonia recovered or discharged from an engine and each pipe when ammonia fuel supply is interrupted due to a fuel change or engine stop, or when ammonia in the fuel supply system must be discharged in specific situations such as maintenance or emergency stop situations, while effectively supplying ammonia fuel to an engine.

[0020] In addition, the present invention proposes a fuel supply system capable of quickly recovering fuel from an engine and each pipe in an emergency stop situation, and a fuel recovery method using the same.

[0021] According to one embodiment of the present invention, a purging system for a ship includes a fuel storage tank for storing liquefied gas fuel; a fuel supply line for supplying liquefied gas fuel in the fuel storage tank to an engine; a purging gas supply line connected to the fuel supply line for supplying purging gas; a separator for storing residual liquefied gas transported by the purging gas supplied from the purging gas supply line; a primary purging line connecting the engine to the separator; and a liquefaction line for returning from the fuel storage tank to the fuel storage tank via the separator, wherein the gaseous liquefied gas stored in the separator is liquefied by the liquid liquefied gas in the fuel storage tank flowing along the liquefaction line.

[0022] In one example, the liquefaction line within the separator may be formed in a coil shape.

[0023] In one example, the separator may include a vent line that supplies the liquefied gas and purging gas stored in the gas phase to a vent gas treatment system.

[0024] In one example, the separator may include a recycle line connecting the separator and the fuel supply line, and the liquid liquefied gas stored in the separator may be supplied to the fuel supply line along the recycle line.

[0025] In one example, a secondary purging line branching from the primary purging line and connected to a vent gas treatment system may be included, and a knockout drum may be provided in the secondary purging line.

[0026] In one example, the knockout drum may include a recovery tank for storing the liquid liquefied gas contained therein.

[0027] A purging method for a ship according to one embodiment of the present invention comprises: a first purging gas supply step of supplying purging gas to an engine and a first purging line; a residual liquefied gas storage step of storing residual liquefied gas transported by the purging gas supplied to the first purging gas supply step in a separator; a residual liquefied gas liquefaction step of liquefying gas in a gaseous state stored in the separator by liquid liquefied gas in a fuel storage tank; a first venting step of supplying gaseous liquefied gas and purging gas stored in the separator to a vent gas treatment system; a second purging gas supply step of supplying purging gas to an engine and a second purging line; and a second venting step of supplying gaseous liquefied gas and purging gas vaporized according to a pressure drop to the vent gas treatment system.

[0028] Meanwhile, an ammonia boil-off gas re-liquefaction system according to one embodiment of the present invention is an ammonia boil-off gas re-liquefaction system for re-liquefying ammonia boil-off gas, the system including: a cargo tank storing cargo ammonia; a fuel tank storing fuel supply ammonia; a main re-liquefaction line re-liquefying boil-off gas generated from the cargo tank using a refrigerant; a sub-re-liquefaction line branched from the main re-liquefaction line re-liquefying boil-off gas generated from the cargo tank using the fuel supply ammonia; a fuel supply line supplying fuel supply ammonia stored in the fuel tank to a fuel supply system; a first heat exchanger disposed on the main re-liquefaction line for heat-exchanging the refrigerant and the boil-off gas; and a second heat exchanger disposed on the sub-re-liquefaction line and the fuel supply line for heat-exchanging the fuel supply ammonia and the boil-off gas.

[0029] In one example, the system may further include a control unit that controls the flow of the evaporation gas so that the evaporation gas is selectively supplied to either the first heat exchanger or the second heat exchanger.

[0030] In one example, the control unit can control the flow of the evaporation gas so that in a fuel non-supply situation where the ammonia for fuel supply is not supplied to the fuel supply system, the evaporation gas is supplied to the first heat exchanger through the main re-liquefaction line, and in a fuel supply situation where the ammonia for fuel supply is supplied to the fuel supply system, the evaporation gas is supplied to the second heat exchanger through the sub re-liquefaction line.

[0031] In one example, the system further includes a first supply valve provided on the main re-liquefaction line at the front end of the first heat exchanger; and a second supply valve provided on the sub-re-liquefaction line at the front end of the second heat exchanger, wherein the control unit can control the opening and closing of the first supply valve and the second supply valve according to the fuel non-supply situation and the fuel supply situation.

[0032] In one example, a compressor may be further provided at the front end of the first heat exchanger and the second heat exchanger to compress the evaporated gas.

[0033] In one example, the control unit can control the compressor so that the evaporation gas is compressed to different pressures depending on the heat exchanger to which the evaporation gas is supplied.

[0034] Meanwhile, a boil-off gas re-liquefaction system according to one embodiment of the present invention is a boil-off gas re-liquefaction system for re-liquefying boil-off gas, and may include: a cargo tank for storing liquid cargo; a fuel tank for storing ammonia for fuel supply; a re-liquefaction line for re-liquefying boil-off gas generated from the cargo tank using the ammonia for fuel supply; a fuel supply line for supplying the ammonia for fuel supply stored in the fuel tank to a fuel supply system; and a heat exchanger disposed on the re-liquefaction line and the fuel supply line for heat exchange between the ammonia for fuel supply and the boil-off gas.

[0035] In one example, the fuel supply line between the heat exchanger and the fuel supply system may further include a reserve fuel tank for storing ammonia for fuel supply that has passed through the heat exchanger.

[0036] In one example, the reserve fuel tank may be provided as a pressurized tank.

[0037] In one example, the method may further include a control unit that controls the flow of the ammonia for fuel supply so that the ammonia for fuel supply is supplied to the fuel supply system in a fuel supply situation and the ammonia for fuel supply is stored in the reserve fuel tank in a fuel non-supply situation.

[0038] In one example, the fuel supply system may further include a reserve fuel storage line for delivering the ammonia for fuel supply on the fuel supply line to the reserve fuel tank; a reserve fuel supply line for delivering the ammonia for fuel supply stored in the reserve fuel tank to the fuel supply line connected to the fuel supply system; a first valve provided on the fuel supply line between the reserve fuel storage line and the reserve fuel supply line; a second valve provided on the reserve fuel storage line; and a third valve provided on the reserve fuel supply line.

[0039] In one example, the control unit can control the opening and closing of the first valve, the second valve, and the third valve.

[0040] In one example, the system may further include a compressor disposed on the re-liquefaction line between the cargo tank and the heat exchanger to compress the evaporated gas.

[0041] Meanwhile, a fuel supply system according to one embodiment of the present invention may include a fuel supply line for supplying fuel from a fuel tank to an engine; a purging gas supply line connected to the fuel supply line for supplying purging gas in a fuel supply stop situation; a separator for receiving and storing unused fuel and purging gas from the engine; a first fuel recovery line configured to primarily recover unused fuel and purging gas from the engine to the separator; a second fuel recovery line configured to secondarily recover unused fuel and purging gas from the engine to the fuel tank; a gas recovery line configured to merge gaseous fuel and purging gas from the separator into the second fuel recovery line; and a liquid recovery line configured to merge liquid fuel from the separator into the fuel supply line.

[0042] In one example, the fuel tank may further include a vent line for supplying purging gas to the aftertreatment unit.

[0043] In one example, the fuel tank may be provided as a pressurized tank.

[0044] In one example, the fuel tank may be provided as a low-pressure operating tank.

[0045] In one example, the system further includes a re-liquefaction system provided on the vent line, wherein the vent line discharges gaseous fuel together with a purging gas from the fuel tank, and at least a portion of the gaseous fuel delivered through the vent line can be re-liquefied by the re-liquefaction system and delivered to the fuel tank.

[0046] In one example, the post-processing unit may include a boiler that uses the purging gas delivered through the vent line as fuel.

[0047] In addition, a fuel supply system according to another embodiment of the present invention may include a fuel supply line for supplying fuel from a fuel tank to an engine; a purging gas supply line connected to the fuel supply line for supplying purging gas in a fuel supply stop situation; a fuel recovery line for transferring unused fuel and purging gas from the engine to the fuel tank; and a vent line for supplying purging gas within the fuel tank to a post-treatment unit.

[0048] In addition, the fuel recovery method of the present invention is a method of recovering fuel using the above-described fuel supply system, comprising: a purging gas supply step of supplying purging gas; a first fuel recovery step of recovering unused fuel and purging gas to a separator through a first fuel recovery line; and a second fuel recovery step of recovering unused fuel and purging gas to a fuel tank through a second fuel recovery line, and in a normal stop situation, the purging gas supply step, the first fuel recovery step, and the second fuel recovery step can be performed, and in an emergency stop situation, the purging gas supply step and the second fuel recovery step can be performed.

[0049] The purging system for a ship of the present invention can reduce the concentration of liquefied gas in the gas phase vented from the separator, thereby reducing the capacity of the vent gas treatment system, thereby increasing space utilization and reducing energy consumption.

[0050] Meanwhile, the evaporation gas re-liquefaction system according to one embodiment of the present invention has the effect of improving re-liquefaction efficiency.

[0051] Meanwhile, the fuel supply system according to the present invention and the fuel recovery method using the same can reduce the volume occupied by the entire system by utilizing the fuel tank as a buffer tank that accommodates gaseous ammonia and purging gas.

[0052] In addition, the fuel supply system according to the present invention and the fuel recovery method using the same can effectively process ammonia recovered or discharged from the engine and each pipe when ammonia fuel supply is interrupted due to a fuel change or engine stop, or when ammonia in the fuel supply system needs to be discharged in specific situations such as maintenance or emergency stop situations.

[0053] In addition, the fuel supply system according to the present invention and the fuel recovery method using the same can quickly recover fuel from the engine and each pipe in an emergency stop situation.

[0054] Figure 1 is a drawing of a purging system for a ship according to the present invention.

[0055] Figure 2 is a drawing illustrating the flow of primary purging gas and liquefied gas for liquefaction in a purging system for a ship according to the present invention.

[0056] FIG. 3 is a drawing illustrating the flow of secondary purging gas in a purging system for a ship according to the present invention.

[0057] Figure 4 is a flow chart of a purging method for a ship according to the present invention.

[0058] Figure 5 is a drawing illustrating an ammonia evaporation gas re-liquefaction system according to the present invention.

[0059] Figure 6 is a diagram showing the flow of ammonia evaporation gas in a fuel non-supply situation.

[0060] Figure 7 is a diagram showing the flow of ammonia evaporation gas in a fuel supply situation.

[0061] FIG. 8 is a drawing illustrating a evaporated gas re-liquefaction system according to the third embodiment of the present invention.

[0062] FIG. 9 is a drawing illustrating a evaporated gas re-liquefaction system according to the third embodiment of the present invention.

[0063] FIG. 10 is a drawing illustrating a fuel supply system according to the 4-1 embodiment of the present invention.

[0064] Figure 11 is a drawing showing the flow for primarily recovering liquid fuel and purging gas in the fuel supply system of Figure 10.

[0065] Figure 12 is a drawing showing the flow of secondary recovery of gaseous fuel and purging gas in the fuel supply system of Figure 10.

[0066] Fig. 13 is a drawing showing the flow for processing purging gas inside a fuel tank in the fuel supply system of Fig. 10.

[0067] Fig. 14 is a drawing illustrating a fuel supply system according to the 4-2 embodiment of the present invention.

[0068] Figure 15 is a drawing of a fuel recovery method using a fuel supply system according to the present invention.

[0069] Fig. 16 is a drawing illustrating a fuel supply system according to the 4-3 embodiment of the present invention.

[0070] Hereinafter, some embodiments of the present invention will be described in detail with reference to exemplary drawings. When designating components in each drawing, it should be noted that, where possible, identical components are given the same reference numerals, even if they appear in different drawings. Furthermore, when describing embodiments of the present invention, detailed descriptions of known components or functions will be omitted if they are deemed to hinder understanding of the embodiments of the present invention.

[0071] Additionally, terms such as first, second, A, B, (a), (b), etc. may be used to describe components of embodiments of the present invention. These terms are only intended to distinguish the components from other components, and the nature, order, or sequence of the components are not limited by the terms. When it is described that a component is "connected," "coupled," or "connected" to another component, it should be understood that the component may be directly connected or connected to the other component, but another component may also be "connected," "coupled," or "connected" between each component.

[0072] In this specification, the forward / backward, left / right, and up / down directions are referred to for convenience of explanation and may be orthogonal to each other. However, these directions are determined relatively, and the up / down direction does not necessarily imply a vertical direction.

[0073]

[0074] In this specification, the first to fourth embodiments are described, and the number of 's in the drawing symbols of the drawings describing each embodiment is distinguished. For example, FIGS. 1 to 4 describing the first embodiment do not have 's in the drawing symbols, FIGS. 5 to 7 describing the second embodiment have 's added to the drawing symbols, FIGS. 8 to 9 describing the third embodiment have 's added, and FIGS. 10 to 16 describing the fourth embodiment have ''s added.

[0075] It should be understood that the embodiments may be combined with each other as needed, or that one embodiment may be modified to provide a different embodiment. Furthermore, while the claims of this specification are described in the fourth embodiment, they are not limited thereto, and that the configuration may be added or modified with reference to other embodiments.

[0076]

[0077] <Example 1>

[0078] 1st purging process

[0079] Referring to FIG. 1, a purging system (100) for a ship according to the present invention comprises: a fuel storage tank (10) for storing liquefied gas fuel; a fuel supply line (FSL) for supplying the liquefied gas fuel of the fuel storage tank (10) to an engine (20); a purging gas supply line (PSL) connected to the fuel supply line (FSL) for supplying purging gas; a separator (50) for storing residual liquefied gas transported by the purging gas supplied from the purging gas supply line (PSL); a primary purging line (PL1) for connecting the separator (50) from the engine (20); And it includes a liquefaction line (LFL) that returns the liquefied gas from the fuel storage tank (10) through the separator (50) back to the fuel storage tank (10), and the liquefied gas in the gas phase stored in the separator (50) is liquefied by the liquefied gas in the liquid phase in the fuel storage tank (10) that flows along the liquefaction line (LFL).

[0080]

[0081] The fuel storage tank (10) can store liquefied gas fuel in a liquid state. Since the fuel storage tank (10) must maintain a predetermined pressure and temperature to store the liquefied gas fuel in a liquid state, it may be an insulated tank capable of blocking heat exchange with the outside. The liquefied gas in the present invention may be ammonia, but is not limited thereto.

[0082] A pump (12) may be installed inside the fuel storage tank (10). The pump (12) serves to transfer liquefied gas fuel to the engine (20). The liquefied gas fuel in the fuel storage tank (10) may be supplied to the engine (20) through a fuel supply line (FSL). The fuel supply line (FSL) may be defined as a line connecting the fuel storage tank (10) and the engine (20). A heat exchanger (14) and a pump (16) may be provided in the fuel supply line (FSL) to adjust the temperature and pressure of the fuel required for the engine (20). The pump (12) in the fuel storage tank (10) may be a low-pressure pump, and the pump (16) on the fuel supply line (FSL) may be a high-pressure pump. In addition, a low-pressure filter (13) may be provided at the rear end of the low-pressure pump (12) of the fuel supply line (FSL), and a high-pressure filter (15) may be provided at the rear end of the high-pressure pump (16).

[0083] In the event of a fuel supply interruption to the engine (20) or other emergency situation, a purging gas supply unit (40) may be provided to send the liquefied gas fuel remaining inside the engine (20) or the fuel supply system to the vent gas treatment system (30). The purging gas may be supplied from the purging gas supply unit (40) to the fuel supply line (FSL) and the engine (20) through a purging gas supply line (PSL). The purging gas supply line (PSL) may be defined as a line connecting the purging gas supply unit (40) and the fuel supply line (FSL). Specifically, the purging gas supply line (PSL) may be connected to the fuel supply line (FSL) at a downstream end of a valve (81) on the fuel supply line (FSL). When the purging gas is supplied to the engine (20) through the purging gas supply line (PSL), the valve (81) on the fuel supply line (FSL) may be automatically closed.

[0084] Purging gas supplied from the purging gas supply line (PSL) may pass through the engine (20) and along the primary purging line (PL1) to be stored in the separator (50) together with the remaining liquefied gas. The primary purging line (PL1) may be defined as a line connecting the engine (20) and the separator (50). The remaining liquefied gas may be liquid ammonia, but is not limited thereto. A valve (82) may be provided in the primary purging line (PL1), and the valve (82) may be opened when the purging gas is supplied primarily.

[0085] The separator (50) may be maintained at a high pressure to maintain the liquefied gas within it in a liquid state. However, the liquefied gas in a gaseous state may exist within the separator (50). Accordingly, the separator (50) may contain purging gas, liquid liquefied gas, and gaseous liquefied gas. When ammonia is used as the liquefied gas, the gaseous liquefied gas present within the separator (50) cannot be discharged as is due to its toxicity, but must be recovered and recycled or discharged through a vent gas treatment system (30).

[0086] The vent gas treatment system (30) may be, for example, an ammonia treatment system for treating toxic ammonia when ammonia is used as a weakening gas. For example, the vent gas treatment system (30) may be an ammonia dissolution system for dissolving ammonia, and may be at least one of an absorption tank for dissolving ammonia gas in water, a scrubber for spraying water onto the ammonia gas, or an integrated scrubber in which the absorption tank and the scrubber are combined. The type of the vent gas treatment system (30) is only an example and is not limited thereto, and the vent gas treatment system (30) may be an ammonia treatment system for reducing the solubility of toxic ammonia. Therefore, as the amount of liquefied gas in the gas phase increases, the capacity of the vent gas treatment system (30) inevitably increases, which causes problems such as space constraints and increased energy consumption.

[0087] To solve this problem, the present invention utilizes the cooling heat of the liquid liquefied gas in the fuel storage tank (10) to liquefy the gaseous liquefied gas stored in the separator (50), thereby reducing the ammonia concentration of the gas vented from the separator (50) to the vent gas treatment system (30).

[0088] A liquefaction line (LFL) may be defined as a line that returns from a fuel storage tank (10) through a separator (50) and back to the fuel storage tank (10). As illustrated in FIG. 1, the liquefaction line (LFL) may be a line that branches from a fuel supply line (FSL), passes through a separator (50), and returns to the fuel storage tank (10). A valve (83) may be provided on the liquefaction line (LFL), and when liquefying a gaseous liquefied gas within the separator (50), the valve (83) may be opened.

[0089] The liquid liquefied gas in the fuel storage tank (10) can be supplied to the separator (50) along the liquefaction line (LFL) and used to liquefy the gaseous liquefied gas stored in the separator (50). That is, the liquid liquefied gas in the fuel storage tank (10) can provide the cooling heat required to liquefy the gaseous liquefied gas stored in the separator (50). Therefore, the ammonia concentration of the gas vented from the separator (50) to the vent gas treatment system (30) can be lowered, resulting in a reduction in the capacity and required energy consumption of the vent gas treatment system (30).

[0090] According to one embodiment, the liquefaction line (LFL) within the separator (50) may be formed in a coil shape. A portion of the liquefaction line (LFL) may be formed in a coil shape, thereby improving the heat exchange efficiency between the liquid liquefied gas of the fuel storage tank (10) and the gaseous liquefied gas of the separator (50).

[0091] According to one embodiment, the purging system (100) for a ship according to the present invention may include a vent line (BTL) for supplying gaseous liquefied gas and purging gas stored in a separator (50) to a vent gas treatment system (30). Some of the non-liquefied gaseous liquefied gas may be vented to the vent gas treatment system (30) together with the purging gas. In addition, a valve (84) may be provided on the vent line (BTL), and when supplying gaseous liquefied gas and purging gas to the vent gas treatment system (30), the valve (84) may be opened.

[0092] According to one embodiment, a purging system (100) for a ship according to the present invention includes a recycle line (RCL) connecting a separator (50) and a fuel supply line (FSL), and liquid liquefied gas stored in the separator (50) can be supplied to the fuel supply line (FSL) along the recycle line (RCL).

[0093] The liquid liquefied gas at the bottom of the separator (50) can be supplied to the fuel supply line (FSL) along the recycle line (RCL) to be re-supplied to the engine (20) when the engine (20) is operated later. A heat exchanger (52) can be provided on the recycle line (RCL) to adjust the required temperature of the liquefied gas supplied to the engine (20). In addition, a valve (85) can be provided on the recycle line (RCL) so that the valve (85) can be opened when the liquid liquefied gas stored in the separator (50) is recycled.

[0094] The purging gas flow along the primary purging line (PL1) is intended to remove any remaining liquid liquefied gas in the engine (20) and related piping, and may be referred to as the primary purging process. Referring to Fig. 2, the flow of purging gas in the primary purging process and the flow of liquid liquefied gas within the fuel storage tank (10) are illustrated.

[0095]

[0096] Secondary purging process

[0097] According to one embodiment, a purging system (100) for a ship according to the present invention includes a secondary purging line (PL2) branched from a primary purging line (PL1) and connected to a vent gas treatment system (30), and a knockout drum (60) may be provided in the secondary purging line (PL2).

[0098] During the first purging process, some liquid liquefied gas and gaseous liquid gas may still remain inside the engine (20) and related piping. A second purging process may be performed to completely remove such remaining liquefied gas.

[0099] In the secondary purging process, the purging gas supplied from the purging gas supply line (PSL) can be supplied to the vent gas treatment system (30) through the knockout drum (60) along the secondary purging line (PL2) through the engine (20) together with the remaining liquefied gas. A valve (86) is provided in the secondary purging line (PL2), and during the secondary purging process, the valve (86) can be opened and the valve (82) can be closed.

[0100] The vent gas treatment system (30) is at atmospheric pressure, and accordingly, the knockout drum (60) is also at almost atmospheric pressure. Therefore, when the valve (86) is opened, the inside of the engine (20) and the related piping drop to almost atmospheric pressure, and any remaining liquefied gas is vaporized and can be supplied to the vent gas treatment system (30) along the secondary purging line (PL2). Referring to Fig. 3, the flow of the purging gas during the secondary purging process is illustrated.

[0101] As the first purging process and the second purging process are performed, the liquefied gas remaining in the engine (20) and related pipes can be liquefied and stored in the separator (50) or vaporized and supplied to the vent gas treatment system (30).

[0102]

[0103] emergency stop

[0104] According to the present invention, the first purging process and the second purging process are referred to as normal stop, and when the engine (20) is stopped in an emergency, it is referred to as an emergency stop. In the case of an emergency stop, purging gas is not supplied to the separator (50) according to the first purging process, and only the second purging process can be performed. In the case of an emergency stop of the engine, since the inside of the engine (20) must be quickly depressurized, only the second purging process is performed, and when this happens, a significant amount of liquid liquefied gas flows into the knockout drum (60). Therefore, a recovery tank (70) for storing the liquid liquefied gas contained in the knockout drum (60) may be additionally included. The liquid liquefied gas stored in the recovery tank (70) can then be recovered by the separator (50). The recovery tank (70) can be used not only in the case of an emergency stop, but also, if necessary, in the secondary purging process of a normal stop.

[0105]

[0106] Purging method for ships

[0107] Referring to FIG. 4, a purging method (S100) for a ship according to the present invention includes: a first purging gas supply step (S10) of supplying purging gas to an engine (20) and a first purging line (PL1); a residual liquefied gas storage step (S20) of storing residual liquefied gas transported by the purging gas supplied to the first purging gas supply step (S10) in a separator (50); a residual liquefied gas liquefaction step (S30) of liquefying gas in a gaseous state stored in the separator (50) by liquid liquefied gas in a fuel storage tank (10); a first venting step (S40) of supplying gaseous liquefied gas and purging gas stored in the separator (50) to a vent gas treatment system (30); a second purging gas supply step (S50) of supplying purging gas to the engine (20) and a second purging line (PL2); And it includes a second venting step (S60) that supplies the liquefied gas and purging gas of the vaporized gas according to the pressure drop to the vent gas treatment system (30).

[0108] The steps described above do not necessarily occur in chronological order and may occur simultaneously.

[0109]

[0110] <Example 2>

[0111] Hereinafter, an ammonia evaporation gas re-liquefaction system (1') according to the present invention will be described with reference to the drawings. The ammonia evaporation gas re-liquefaction system (1') according to the present invention is a system for re-liquefying ammonia evaporation gas, and aims to improve re-liquefaction efficiency by condensing and re-liquefying the evaporation gas through different heat exchangers in an ammonia fuel supply situation and an ammonia fuel non-supply situation.

[0112] The ammonia evaporation gas re-liquefaction system (1') according to the present invention can be installed in a transportation means that transports ammonia and uses ammonia as fuel. In this embodiment, the ammonia evaporation gas re-liquefaction system (1') is installed in a ship as an example, but the spirit of the present invention is not limited thereto.

[0113] Figure 5 is a drawing illustrating an ammonia evaporation gas re-liquefaction system (1') according to the present invention.

[0114] Referring to FIG. 5, the ammonia evaporation gas re-liquefaction system (1') according to the present invention comprises a cargo tank (10') for storing cargo ammonia, a fuel tank (20') for storing fuel supply ammonia, a main re-liquefaction line (L1') for re-liquefying evaporation gas generated from the cargo tank (10') using a refrigerant, a sub-re-liquefaction line (L2') branched from the main re-liquefaction line (L1') for re-liquefying evaporation gas generated from the cargo tank (10') using ammonia for fuel supply, a fuel supply line (L3') for supplying ammonia for fuel supply stored in the fuel tank (20') to a fuel supply system (70'), a first heat exchanger (40') arranged on the main re-liquefaction line (L1') for exchanging heat between the refrigerant and the evaporation gas, and a second heat exchanger (40') arranged on the sub-re-liquefaction line (L2') and the fuel supply line (L3') for re-liquefying evaporation gas generated from the cargo tank (10') using a refrigerant. It may include a second heat exchanger (50') for heat exchange between the supply ammonia and the evaporated gas.

[0115] Specifically, the ammonia evaporation gas re-liquefaction system (1') according to the present invention may include a cargo tank (10'), a fuel tank (20'), a compressor (30'), a first heat exchanger (40'), a second heat exchanger (50'), a cargo receiver (60'), and a fuel supply system (70'). In addition, a main re-liquefaction line (L1'), a sub re-liquefaction line (L2'), and a fuel supply line (L3') may be provided as lines connecting these components. In addition, a refrigerant delivery line (L4') for supplying refrigerant to the first heat exchanger (40') and discharging refrigerant from the first heat exchanger (40'), and a vent line (L5') for discharging impurities or non-condensable gases from the cargo receiver (60') may be provided.

[0116] The main reliquefaction line (L1') can be connected to the cargo tank (10') and then connected to the cargo tank (10') again via the compressor (30'), the first heat exchanger (40'), and the cargo receiver (60'). The sub reliquefaction line (L2') can be branched from the main reliquefaction line (L1') at the rear end of the compressor (30') and the front end of the first heat exchanger (40') (branched from the main reliquefaction line (L1') between the compressor (30') and the first heat exchanger (40')) and joined to the main reliquefaction line (L1') again at the front end of the cargo receiver (60') (joined to the main reliquefaction line (L1') between the first heat exchanger (40') and the cargo receiver (60'). The fuel supply line (L3') can be connected to the fuel tank (20') and connected to the fuel supply system (70') via the second heat exchanger (50').

[0117] Ammonia for cargo to be transported via a ship can be stored in a cargo tank (10'), and ammonia for fuel to be supplied to a fuel supply system (70') can be stored in a fuel tank (20').

[0118] At this time, the fuel supply system (70') receives ammonia fuel from the fuel tank (20') and supplies it to each demander. For example, the fuel supply system (70') can supply ammonia fuel to the engine to generate propulsion power for the ship or to produce the electricity required for the ship.

[0119] Meanwhile, the cargo tank (10') and the fuel tank (20') can store ammonia in a liquid state. At this time, ammonia vaporization may generate ammonia vaporization gas in the cargo tank (10') and the fuel tank (20'). The present invention is for re-liquefying the ammonia vaporization gas generated in the cargo tank (10'), and the ammonia vaporization gas is re-liquefied through a compression and condensation process. In the following description, the vaporization gas refers to the ammonia vaporization gas generated in the cargo tank (10').

[0120] The ammonia evaporation gas re-liquefaction system (1') according to the present invention may be equipped with a first heat exchanger (40') for heat-exchanging a refrigerant and evaporation gas, and a second heat exchanger (50') for heat-exchanging ammonia for fuel supply and evaporation gas. The ammonia evaporation gas re-liquefaction system (1') according to the present invention may use the first heat exchanger (40') in a fuel non-supply situation where ammonia for fuel supply in a fuel tank (20') is not supplied to a fuel supply system (70'), and may use the second heat exchanger (50') in a fuel supply situation where ammonia for fuel supply in a fuel tank (20') is supplied to a fuel supply system (70'). A more specific description thereof will be given later.

[0121] In this embodiment, the refrigerant used for heat exchange in the first heat exchanger (40') is described as seawater, but the spirit of the present invention is not limited thereto. As other examples, other refrigerants such as fresh water, nitrogen, and CO2 may be used.

[0122] The first heat exchanger (40') is configured to exchange heat between seawater and the boil-off gas, and may be installed on the main re-liquefaction line (L1') and the refrigerant delivery line (L4'). The main re-liquefaction line (L1') may deliver the boil-off gas to the first heat exchanger (40') to condense the boil-off gas using the first heat exchanger (40'). The first heat exchanger (40') may exchange heat between the boil-off gas delivered through the main re-liquefaction line (L1') and the refrigerant supplied through the refrigerant delivery line (L4').

[0123] Meanwhile, a compressor (30') may be provided on the main re-liquefaction line (L1') in front of the first heat exchanger (40') and the second heat exchanger (50'). The compressor (30') may compress the evaporation gas before the evaporation gas is transferred to the first heat exchanger (40') or the second heat exchanger (50'). By compressing the evaporation gas and then condensing it, the condensation efficiency may be increased.

[0124] At this time, the compressor (30') compresses the evaporation gas to different pressures depending on the temperature of the object with which the evaporation gas is heat-exchanged. Specifically, since the saturation pressure of the evaporation gas varies depending on the temperature after heat exchange, the compressor (30') can compress the evaporation gas to a pressure higher than this saturation pressure.

[0125] The temperature of seawater supplied to the first heat exchanger (40') is about 30°C, and the temperature of ammonia for fuel supply supplied to the second heat exchanger (50') is about -30°C. Therefore, in a fuel non-supply situation where the boil-off gas is supplied to the first heat exchanger (40'), the compressor (30') compresses the boil-off gas to a relatively higher pressure than in a fuel supply situation where the boil-off gas is supplied to the second heat exchanger (50').

[0126] A cargo receiver (60') is provided at the rear end of the heat exchangers (40', 50') to receive condensed boil-off gas and temporarily store the condensed boil-off gas. Specifically, the cargo receiver (60') may be provided on the main re-liquefaction line (L1') at the rear end of the first heat exchanger (40'). In addition to the condensed boil-off gas, impurities or non-condensable gases may also flow into the cargo receiver (60'), and the cargo receiver (60') may separate the impurities or non-condensable gases and discharge them through the vent line (L5'). A vent valve (62') for discharging the impurities or non-condensable gases may be provided on the vent line (L5'), and a return valve (61') may be provided on the main re-liquefaction line (L1') at the rear end of the cargo receiver (60').

[0127] The second heat exchanger (50') is configured to heat-exchange ammonia for fuel supply and the boil-off gas, and may be provided on the sub-reliquefaction line (L2') and the fuel supply line (L3'). Specifically, the second heat exchanger (50') can heat-exchange the boil-off gas delivered through the sub-reliquefaction line (L2') and the ammonia for fuel supply delivered through the fuel supply line (L3'). The second heat exchanger (50') condenses the boil-off gas using the cold heat of the ammonia for fuel supply supplied to the fuel supply system (70'), thereby increasing the condensation efficiency.

[0128] In addition, as described above, the ammonia for fuel supply delivered to the second heat exchanger (50') may have a temperature of approximately -30°C. In the second heat exchanger (50'), the evaporation gas is condensed using the relatively low-temperature ammonia for fuel supply, and in this case, the compressor (30') compresses the evaporation gas at a relatively low pressure. Accordingly, the load on the compressor (30') can be reduced.

[0129] A control unit (not shown) can control the flow of the evaporation gas so that the evaporation gas is supplied to either the first heat exchanger (40') or the second heat exchanger (50'). Specifically, the control unit can control the flow of the evaporation gas so that in a fuel non-supply situation, the evaporation gas is supplied to the first heat exchanger (40') through the main re-liquefaction line (L1'), and in a fuel supply situation, the evaporation gas is supplied to the second heat exchanger (50') through the sub re-liquefaction line (L2').

[0130] To this end, the control unit can control the opening and closing of the first supply valve (41') and the second supply valve (51'). The first supply valve (41') can be provided on the main re-liquefaction line (L1') of the front end of the first heat exchanger (40'), and the second supply valve (51') can be provided on the sub-re-liquefaction line (L2') of the front end of the second heat exchanger (50'). In a fuel non-supply situation, the control unit can open the first supply valve (41') and close the second supply valve (51') to supply the boil-off gas to the first heat exchanger (40'). In addition, in a fuel supply situation, the control unit can close the first supply valve (41') and open the second supply valve (51') to supply the boil-off gas to the second heat exchanger (50').

[0131] Additionally, when it is desired to discharge impurities from the cargo receiver (60'), the control unit can close the return valve (61') and open the vent valve (62'). On the other hand, when it is desired to transfer the condensed evaporated gas to the cargo tank (10'), the control unit can open the return valve (61') and close the vent valve (62').

[0132] In addition, the control unit can control the compressor (30') so that the evaporation gas is compressed to different pressures depending on the heat exchanger (40', 50') to which the evaporation gas is supplied. Specifically, the control unit can control the compressor (30') so that the evaporation gas is compressed to a relatively high pressure so that the evaporation gas is condensed through heat exchange with seawater having a relatively high temperature in a fuel non-supply situation. In addition, the control unit can control the compressor (30') so that the evaporation gas is condensed through heat exchange with ammonia for fuel supply having a relatively low temperature in a fuel supply situation.

[0133] In each heat exchanger, the compressor (30') can be controlled so that the evaporation gas is compressed to different pressures depending on the temperature of the object with which the evaporation gas is exchanged.

[0134] Hereinafter, with reference to FIGS. 6 and 7, the process of re-liquefying the evaporated gas in a fuel non-supply situation and a fuel supply situation will be described, respectively.

[0135] Figure 6 is a diagram showing the flow of ammonia evaporation gas in a fuel-free situation. Figure 7 is a diagram showing the flow of ammonia evaporation gas in a fuel-free situation. For reference, Figure 6 depicts the flow of evaporation gas and seawater in a fuel-free situation with solid lines, while Figure 7 depicts the flow of evaporation gas and ammonia for fuel supply in a fuel-free situation with solid lines.

[0136] Referring to Fig. 6, in a fuel non-supply situation, heat exchange can be performed in the first heat exchanger (40'). In a fuel non-supply situation, the boil-off gas generated in the cargo tank (10') can be re-liquefied sequentially through the compressor (30'), the first heat exchanger (40'), and the cargo receiver (60') via the main re-liquefaction line (L1'), and then returned to the cargo tank (10'). In addition, seawater can be introduced into the first heat exchanger (40') via the refrigerant delivery line (L4'), undergo a heat exchange process with the boil-off gas in the first heat exchanger (40'), and then be discharged from the first heat exchanger (40').

[0137] Specifically, the evaporation gas generated in the cargo tank (10') can be compressed in the compressor (30') before being introduced into the first heat exchanger (40'). At this time, since relatively high-temperature seawater is used as a refrigerant in the first heat exchanger (40'), the compressor (30') can compress the evaporation gas to a relatively high pressure.

[0138] At this time, since the first supply valve (41') is open and the second supply valve (51') is closed, the evaporation gas compressed by the compressor (30') can be transferred to the first heat exchanger (40') through the main reliquefaction line (L1'). The evaporation gas and seawater exchange heat in the first heat exchanger (40'). As a result, the evaporation gas can be condensed, and the condensed evaporation gas can be transferred from the first heat exchanger (40') to the cargo receiver (60').

[0139] Impurities or non-condensable gases that flow into the cargo receiver (60') together with the condensed evaporation gas can be discharged to the outside through the vent line (L5'). The condensed evaporation gas can be transferred to the cargo tank (10') again through the main re-liquefaction line (L1') and stored in the cargo tank (10').

[0140] Meanwhile, referring to FIG. 7, in a fuel supply situation, heat exchange can be performed in the second heat exchanger (50'). In a fuel supply situation, the boil-off gas generated in the cargo tank (10') is delivered to the compressor (30') through the main re-liquefaction line (L1'), and then re-liquefied through the second heat exchanger (50') through the sub-liquefaction line (L2'), and then delivered to the cargo receiver (60') through the main re-liquefaction line (L1') and then returned to the cargo tank (10'). In addition, ammonia for fuel supply can be pumped by a pump (21') in the fuel tank (20') and introduced into the second heat exchanger (50') through the fuel supply line (L3'). The ammonia for fuel supply can be delivered to the fuel supply system (70') after undergoing a heat exchange process with the boil-off gas in the second heat exchanger (50').

[0141] Specifically, the evaporation gas generated in the cargo tank (10') can be compressed in the compressor (30') before being introduced into the second heat exchanger (50'). At this time, in the second heat exchanger (50'), the evaporation gas is heat-exchanged with the relatively low-temperature ammonia for fuel supply, so that the compressor (30') can compress the evaporation gas to a relatively low pressure. Accordingly, the load of the compressor (30') can be reduced.

[0142] At this time, since the first supply valve (41') is closed and the second supply valve (51') is open, the evaporation gas compressed by the compressor (30') can be transferred to the second heat exchanger (50') through the sub-reliquefaction line (L2'). In the second heat exchanger (50'), the evaporation gas and ammonia for fuel supply are heat-exchanged. As a result, the evaporation gas can be condensed, and the condensed evaporation gas can be transferred from the second heat exchanger (50') to the cargo receiver (60').

[0143] As in the case of a fuel failure, impurities or non-condensable gases flowing into the cargo receiver (60') together with the condensed evaporation gas in the cargo receiver (60') can be discharged to the outside through the vent line (L5'). The condensed evaporation gas can be transferred to the cargo tank (10') again through the main re-liquefaction line (L1') and stored in the cargo tank (10').

[0144]

[0145] The ammonia evaporation gas re-liquefaction system (1') according to the present invention has a first heat exchanger (40') and a second heat exchanger (50') arranged in parallel so that different heat exchangers can be used in fuel non-supply situations and fuel supply situations, respectively. Specifically, the ammonia evaporation gas re-liquefaction system (1') according to the present invention has a second heat exchanger (50') that can be used in fuel supply situations, so that the ammonia evaporation gas can be re-liquefied by utilizing the cold heat of the ammonia for fuel supply. At this time, since the ammonia for fuel supply is in a low-temperature state, there is no need to compress the ammonia evaporation gas to high pressure, so there is an advantage in that the load of the compressor (30') can be reduced and the re-liquefaction efficiency can be improved.

[0146]

[0147] <Example 3>

[0148] Hereinafter, a boil-off gas re-liquefaction system (1'') according to the present invention will be described with reference to the drawings. The boil-off gas re-liquefaction system (1'') according to the present invention is a system for re-liquefying boil-off gas, and more specifically, is a system for re-liquefying boil-off gas generated from liquid cargo by utilizing the cold heat of ammonia for fuel supply. The present invention can improve the re-liquefaction efficiency by utilizing the cold heat of ammonia for fuel supply for re-liquefaction.

[0149] The evaporation gas re-liquefaction system (1'') according to the present invention can be installed in a transportation means that transports liquid cargo and uses ammonia as fuel. In this embodiment, the evaporation gas re-liquefaction system (1'') is installed in a ship as an example, but the spirit of the present invention is not limited thereto.

[0150]

[0151] Example 3-1

[0152] Fig. 8 is a drawing illustrating a evaporation gas re-liquefaction system (1'') according to the third embodiment of the present invention. Hereinafter, the evaporation gas re-liquefaction system (1'') according to the third embodiment of the present invention will be described with reference to Fig. 8.

[0153] Referring to FIG. 8, a boil-off gas re-liquefaction system (1'') according to the third-first embodiment of the present invention may include a cargo tank (10'') for storing liquid cargo, a fuel tank (20'') for storing ammonia for fuel supply, a re-liquefaction line (L1'') for re-liquefying boil-off gas generated from the cargo tank (10'') using ammonia for fuel supply, a fuel supply line (L2'') for supplying ammonia for fuel supply stored in the fuel tank (20'') to a fuel supply system (60''), and a heat exchanger (40'') disposed on the re-liquefaction line (L1'') and the fuel supply line (L2'') for heat-exchanging ammonia for fuel supply and boil-off gas.

[0154] Specifically, the evaporation gas re-liquefaction system (1'') according to the present invention may include a cargo tank (10''), a fuel tank (20''), a compressor (30''), a heat exchanger (40''), a cargo receiver (50''), and a fuel supply system (60''). In addition, a re-liquefaction line (L1'') and a fuel supply line (L2'') may be provided as lines connecting these components. In addition, a vent line (L3'') for discharging impurities or non-condensable gases from the cargo receiver (50'') may be provided.

[0155] The re-liquefaction line (L1'') is connected to a cargo tank (10''), and can be connected again to the cargo tank (10'') via a compressor (30''), a heat exchanger (40''), and a cargo receiver (50''). The fuel supply line (L2'') is connected to a fuel tank (20''), and can be connected to a fuel supply system (60'') via a heat exchanger (40'').

[0156] The cargo tank (10'') can store liquid cargo to be transported via a ship, and the fuel tank (20'') can store ammonia for fuel supply to be supplied to the fuel supply system (60'').

[0157] At this time, the fuel supply system (60'') receives ammonia fuel from the fuel tank (20'') and supplies it to each demander. For example, the fuel supply system (60'') can supply ammonia fuel to the engine to generate propulsion power for the ship or to produce electricity required for the ship.

[0158] Meanwhile, the cargo tank (10'') can store liquid cargo. The liquid cargo stored in the cargo tank (10'') is a cargo with a boiling point of -110°C or higher, and may be a liquefied version of such cargo. As an example, the liquid cargo may be ammonia, but the scope of the present invention is not limited thereto.

[0159] At this time, the liquid cargo in the cargo tank (10'') may vaporize, generating evaporation gas. The present invention is for re-liquefying the evaporation gas generated in the cargo tank (10''), and re-liquefies the evaporation gas through a compression and condensation process. In the following description, the evaporation gas refers to the evaporation gas of the liquid cargo generated in the cargo tank (10'').

[0160] Below, the flow of evaporated gas generated in the cargo tank (10'') is described.

[0161] First, when evaporation gas is generated, the evaporation gas can be transferred from the cargo tank (10'') to the compressor (30'') through the re-liquefaction line (L1'').

[0162] The compressor (30'') can compress the evaporation gas before it is transferred to the heat exchanger (40''). At this time, the compressor (30'') can be placed on the re-liquefaction line (L1'') between the cargo tank (10'') and the heat exchanger (40''). After the evaporation gas is compressed by the compressor (30''), it is condensed through a heat exchange process in the heat exchanger (40''), thereby increasing the condensation efficiency.

[0163] Specifically, the compressor (30'') compresses the evaporation gas to a pressure higher than the pressure at which the evaporation gas is condensed (i.e., the saturation pressure) and delivers the evaporation gas to the heat exchanger (40''). To this end, the compressor (30'') may be operated in conjunction with the heat exchanger (40''). That is, the compressor (30'') may compress the evaporation gas to different pressures depending on the refrigerant temperature in the heat exchanger (40''). Specifically, when the temperature of the refrigerant is relatively high, the compressor (30'') may compress the evaporation gas to a high pressure. Accordingly, even at a high refrigerant temperature, the evaporation gas may be condensed and re-liquefied. On the other hand, when the temperature of the refrigerant is relatively low, the compressor (30'') may compress the evaporation gas to a low pressure. In this case, the load of the compressor (30'') is reduced, thereby increasing the re-liquefaction efficiency.

[0164] In the present invention, low-temperature fuel supply ammonia supplied to the fuel supply system (60'') is utilized as a refrigerant in the heat exchanger (40''), so that the compressor (30'') can compress the evaporated gas to a low pressure. Accordingly, there is an advantage in that the load on the compressor (30'') can be reduced.

[0165] Specifically, the heat exchanger (40'') is a configuration for exchanging heat between ammonia for fuel supply and the boil-off gas, and can be provided on the re-liquefaction line (L1'') and the fuel supply line (L2''). The heat exchanger (40'') can heat-exchange the boil-off gas delivered through the re-liquefaction line (L1'') and the ammonia for fuel supply delivered through the fuel supply line (L2''). The heat exchanger (40'') condenses the boil-off gas using the cold heat of the ammonia for fuel supply, and thus can increase the condensation efficiency.

[0166] The ammonia for fuel supply delivered to the heat exchanger (40'') may have a temperature of approximately -30°C. As described above, the present invention utilizes such low-temperature ammonia for fuel supply to condense the evaporated gas, which has the advantage of reducing the load on the compressor (30'') and improving the re-liquefaction efficiency.

[0167] A cargo receiver (50'') is provided at the rear end of the heat exchanger (40'') to receive condensed evaporation gas and temporarily store the condensed evaporation gas. Specifically, the cargo receiver (50'') may be provided on a re-liquefaction line (L1'') at the rear end of the heat exchanger (40''). In addition to the condensed evaporation gas, impurities or non-condensable gases may also flow into the cargo receiver (50''), and the cargo receiver (50'') may separate the impurities or non-condensable gases and discharge them through a vent line (L3''). A vent valve (52'') for discharging the impurities or non-condensable gases may be provided on the vent line (L3''), and a return valve (51'') may be provided on the re-liquefaction line (L1'') at the rear end of the cargo receiver (50'').

[0168] Below, the flow of ammonia for fuel supply is described.

[0169] Ammonia for fuel supply stored in a fuel tank (20'') can be pumped through a fuel supply pump (21'') and delivered to a fuel supply system (60'') through a fuel supply line (L2''). At this time, a heat exchanger (40'') is provided on the fuel supply line (L2'') between the fuel tank (20'') and the fuel supply system (60''), and ammonia for fuel supply can be supplied to the fuel supply system (60'') through the heat exchanger (40'').

[0170] In order to control the flow rate of ammonia for fuel supply supplied to the fuel supply system (60''), a supply flow rate control valve (42'') may be provided on the fuel supply line (L2'') between the fuel tank (20'') and the heat exchanger (40''). That is, the flow rate control valve (42'') is arranged at the front end of the heat exchanger (40'') and serves to control the flow rate of ammonia for fuel supply supplied to the heat exchanger (40'').

[0171] Meanwhile, a control unit (not shown) that controls the above-described configurations may be provided.

[0172] The control unit can control the compressor (30'') so that the pressure at which the evaporation gas is compressed in the compressor (30'') is regulated by linking the compressor (30'') with the heat exchanger (40''). As described above, the control unit can control the compressor (30'') so that the evaporation gas is compressed to different pressures depending on the temperature of the ammonia for fuel supply supplied to the heat exchanger (40'').

[0173] Additionally, if the control unit wants to discharge impurities from the cargo receiver (50''), the control unit can close the return valve (51'') and open the vent valve (52''). On the other hand, if the control unit wants to transfer the condensed evaporated gas to the cargo tank (10''), the control unit can open the return valve (51'') and close the vent valve (52'').

[0174] In addition, the control unit can control the opening and closing of the supply flow rate control valve (42'') to control the flow rate of ammonia for fuel supply.

[0175] The evaporation gas re-liquefaction system (1'') according to the third embodiment of the present invention can re-liquefy evaporation gas by utilizing the cold heat of ammonia for fuel supply. At this time, since the ammonia for fuel supply is in a low temperature state, there is no need to compress the evaporation gas to high pressure, which has the advantage of reducing the load on the compressor (30'') and improving the re-liquefaction efficiency.

[0176]

[0177] Example 3-2

[0178] FIG. 9 is a drawing illustrating a evaporation gas re-liquefaction system (100'') according to the third embodiment of the present invention. Hereinafter, the evaporation gas re-liquefaction system (100'') according to the third embodiment of the present invention will be described with reference to FIG. 9. However, the evaporation gas re-liquefaction system (100'') according to the third embodiment of the present invention is different from the evaporation gas re-liquefaction system (1'') according to the third embodiment of the present invention in that a reserve fuel tank (70'') is provided, and therefore, the differences will be mainly described, and the description and drawing symbols of the third embodiment described above will be used for the same parts.

[0179] Referring to FIG. 9, the evaporation gas re-liquefaction system (100'') according to the present invention may include a cargo tank (10''), a fuel tank (20''), a compressor (30''), a heat exchanger (40''), a cargo receiver (50''), a fuel supply system (60''), and a reserve fuel tank (70''). In addition, as lines connecting these components, a re-liquefaction line (L1''), a fuel supply line (L2''), a reserve fuel storage line (L4''), and a reserve fuel supply line (L5'') may be provided. In addition, a vent line (L3'') for discharging impurities or non-condensable gases from the cargo receiver (50'') may be provided.

[0180] The evaporation gas re-liquefaction system (100'') according to the third embodiment of the present invention is intended to always re-liquefy the evaporation gas using ammonia for fuel supply, regardless of whether fuel supply is necessary in the fuel supply system (60'').

[0181] Specifically, the evaporation gas re-liquefaction system (100'') according to the third-second embodiment of the present invention includes a reserve fuel tank (70'') connected to a fuel supply line (L2'') between a heat exchanger (40'') and a fuel supply system (60''). The reserve fuel tank (70'') can store ammonia for fuel supply that has passed through the heat exchanger (40'').

[0182] Ammonia for fuel supply stored in the fuel tank (20'') can be pumped through the fuel supply pump (21'') and supplied to the fuel supply system (60'') through the heat exchanger (40'') or stored in the reserve fuel tank (70'').

[0183] In this embodiment, by providing a reserve fuel tank (70'') as described above, even when fuel supply is unnecessary in the fuel supply system (60''), ammonia for fuel supply delivered through the fuel supply line (L2'') can be temporarily stored for heat exchange in the heat exchanger (40'').

[0184] The reserve fuel tank (70'') can be connected to the fuel supply line (L2'') through a reserve fuel storage line (L4'') and a reserve fuel supply line (L5''). Specifically, the reserve fuel storage line (L4'') can transfer ammonia for fuel supply on the fuel supply line (L2'') to the reserve fuel tank (70''). The ammonia for fuel supply introduced through the reserve fuel storage line (L4'') can be stored in the reserve fuel tank (70''). In addition, the reserve fuel supply line (L5'') can transfer ammonia for fuel supply stored in the reserve fuel tank (70'') to the fuel supply line (L2'') connected to the fuel supply system (60''). For this purpose, one end of the reserve fuel supply line (L5'') can be connected to a reserve fuel supply pump (71'') provided inside the reserve fuel tank (70''), and the other end of the reserve fuel supply line (L5'') can be connected to a fuel supply line (L2'').

[0185] Meanwhile, the reserve fuel tank (70'') may be provided as a pressurized tank. Accordingly, the ammonia for fuel supply inside the reserve fuel tank (70'') may be stored under high pressure. Accordingly, evaporative gas may not be generated in the reserve fuel tank (70''). In addition, since the reserve fuel tank (70'') is provided as a pressurized tank, the reserve fuel supply pump (71'') provided inside the reserve fuel tank (70'') has the advantage of being able to have a low head.

[0186] A vaporization gas flow rate control valve (41'') and a supply flow rate control valve (42'') for controlling the flow rate may be provided on the re-liquefaction line (L1'') and the fuel supply line (L2''). The vaporization gas flow rate control valve (41'') may be provided on the re-liquefaction line (L1'') between the compressor (30'') and the heat exchanger (40'') to control the flow rate of the vaporization gas delivered to the heat exchanger (40''). In addition, the supply flow rate control valve (42'') may be provided on the fuel supply line (L2'') between the fuel tank (20'') and the heat exchanger (40'') to control the flow rate of ammonia for fuel supply delivered to the heat exchanger (40''). That is, the supply flow rate control valve (42'') may be arranged at the front end of the heat exchanger (40'').

[0187] Meanwhile, a control unit (not shown) that controls the above-described configurations may be provided.

[0188] The control unit can control the flow of ammonia for fuel supply according to the fuel supply situation and the fuel non-supply situation. Here, the fuel supply situation may be a situation in which fuel supply is required from the fuel supply system (60''), and the fuel non-supply situation may be a situation in which fuel supply is not required from the fuel supply system (60''). The control unit can control the flow of ammonia for fuel supply so that ammonia for fuel supply is supplied to the fuel supply system (60'') in the fuel supply situation and ammonia for fuel supply is stored in the reserve fuel tank (70'') in the fuel non-supply situation.

[0189] To this end, the control unit can control the opening and closing of valves (81'', 82'', 83'') for controlling the flow of ammonia for fuel supply. Specifically, the evaporative gas re-liquefaction system (100'') according to the present embodiment may be provided with a first valve (81'') provided on a fuel supply line (L2'') between a reserve fuel storage line (L4'') and a reserve fuel supply line (L5''), a second valve (82'') provided on the reserve fuel storage line (L4''), and a third valve (83'') provided on the reserve fuel supply line (L5''). The control unit can control the flow of ammonia for fuel supply by controlling the opening and closing of the first valve (81''), the second valve (82''), and the third valve (83'').

[0190] For example, the control unit may, in a fuel supply situation, cause at least one of the ammonia for fuel supply stored in the reserve fuel tank (70'') and the ammonia for fuel supply delivered from the fuel tank (20'') through the heat exchanger (40'') through the fuel supply line (L2'') to be supplied to the fuel supply system (60'').

[0191] The control unit can drive the reserve fuel supply pump (71'') and open the third valve (83'') to supply ammonia for fuel supply stored in the reserve fuel tank (70'') to the fuel supply system (60'') in a fuel supply situation.

[0192] Additionally, when there is no ammonia for fuel supply stored in the reserve fuel tank (70''), the control unit may open the first valve (81'') and close the second valve (82'') and the third valve (83'') to supply only the ammonia for fuel supply delivered from the heat exchanger (40'') through the fuel supply line (L2'') to the fuel supply system (60'').

[0193] As another example, the control unit may cause both the ammonia for fuel supply stored in the reserve fuel tank (70'') and the ammonia for fuel supply delivered from the fuel tank (20'') through the fuel supply line (L2'') to be supplied to the fuel supply system (60''). In this case, the control unit may drive the reserve fuel supply pump (71''), open the first valve (81'') and the third valve (83''), and close the second valve (82''). At this time, the control unit may appropriately adjust the amount of the ammonia for fuel supply of the reserve fuel tank (70'') and the ammonia for fuel supply of the fuel tank (20'') and supply them to the fuel supply system (60'').

[0194] Additionally, the control unit can close the first valve (81'') and the third valve (83'') and open the second valve (82'') in order to store ammonia for fuel supply in the reserve fuel tank (70'') in a fuel non-supply situation. As a result, all ammonia for fuel supply delivered from the heat exchanger (40'') through the fuel supply line (L2'') can be stored in the reserve fuel tank (70'').

[0195] In addition, the control unit can control the opening and closing of the evaporation gas flow rate control valve (41'') and the supply flow rate control valve (42'') to control the flow rate of the evaporation gas and ammonia for fuel supply.

[0196] The evaporation gas re-liquefaction system (100'') according to the third embodiment of the present invention has the advantage of reducing the load of the compressor (30'') and improving the re-liquefaction efficiency by re-liquefying the evaporation gas using low-temperature fuel supply ammonia.

[0197] In addition, the evaporation gas re-liquefaction system (100'') according to the 3-2 embodiment of the present invention has an advantage in that, by having a reserve fuel tank (70'') that can store ammonia for fuel supply in a fuel non-supply situation, ammonia for fuel supply can always be used as a refrigerant in the heat exchanger (40''), regardless of whether fuel supply is necessary in the fuel supply system (60'').

[0198]

[0199] <Example 4>

[0200] The fuel supply system (1''', 100''', 1000''') according to the present invention is a system that supplies fuel to an engine (20'''), and is intended to effectively process fuel recovered or discharged from the engine (20''') and each pipe in situations such as engine (20''') stoppage or emergency. Hereinafter, a fuel supplied through the fuel supply system (1''', 100''', 1000''') is ammonia as an example. However, the spirit of the present invention is not limited thereto, and other fuels other than ammonia may be applied within the scope that the spirit of the present invention is maintained.

[0201] Specifically, purging is performed to prevent explosion and remove toxic gases due to ammonia remaining in the engine and pipes in situations such as when the engine (20''') is stopped. For example, in order to switch to a fuel other than ammonia, ammonia remaining in the engine (20''') and each pipe is removed, and for another example, when the inside of the system is to be maintained or in an emergency, ammonia remaining in the engine and each pipe must be removed. For convenience of explanation, this situation is referred to as a 'fuel supply stop situation' below. In addition, a situation in which fuel is supplied to the engine (20''') to drive the engine (20''') is referred to as a 'fuel supply situation'.

[0202] The fuel supply system (1''') includes a fuel supply line (FSL''') that supplies fuel from a fuel tank (10''') to an engine (20'''), a purging gas supply line (PSL''') that is connected to the fuel supply line (FSL''') and supplies purging gas in a fuel supply stop situation; It may include a separator (30''') that receives and stores unused fuel and purging gas from an engine (20'''), a first fuel recovery line (RL1''') that is provided to primarily recover unused fuel and purging gas from the engine (20''') to the separator (30'''), a second fuel recovery line (RL2''') that is provided to secondarily recover unused fuel and purging gas from the engine (20''') to the fuel tank (10'''), a gas recovery line (RL3''') that is provided to merge gaseous fuel and purging gas from the separator (30''') to the second fuel recovery line (RL2'''), and a liquid recovery line (RL4''') that is provided to merge liquid fuel from the separator (30''') to the fuel supply line (FSL).

[0203] Hereinafter, a fuel supply system (1''', 100''', 1000''') according to each embodiment of the present invention will be described with reference to the drawings.

[0204]

[0205] <Example 4-1>

[0206] Fig. 10 is a drawing illustrating a fuel supply system (1''') according to the 4-1 embodiment of the present invention. Hereinafter, the fuel supply system (1''') according to the 4-1 embodiment will be described with reference to Fig. 10.

[0207] A fuel supply system (1''') according to the 4-1 embodiment of the present invention may include a fuel tank (10'''), an engine (20'''), a separator (30'''), a post-treatment unit (40'''), and a purging gas supply unit (60'''). In addition, as lines interconnecting components of the fuel supply system (1'''), it may include a fuel supply line (FSL'''), a first fuel recovery line (RL1'''), a second fuel recovery line (RL2'''), a gas recovery line (RL3'''), a liquid recovery line (RL4'''), a vent line (VL'''), and a purging gas supply line (PSL''').

[0208] The fuel tank (10''') may store fuel to be supplied to the engine (20'''). At this time, the fuel stored in the fuel tank (10''') may be ammonia, and the fuel tank (10''') may be provided as a pressurized tank, but the spirit of the present invention is not limited thereto. A supply pump (11''') for supplying fuel may be provided within the fuel tank (10''').

[0209] The engine (20''') can be driven by receiving ammonia fuel from the fuel tank (10'''). For example, the fuel supply system (1''') according to the present invention can be provided to a ship, and the engine (20''') can generate propulsion power and electric power for the ship.

[0210] As a line connecting the fuel tank (10''') and the engine (20'''), a fuel supply line (FSL''') and a second fuel return line (RL2''') may be provided.

[0211] The fuel supply line (FSL''') can supply ammonia fuel from the fuel tank (10''') to the engine (20'''). At this time, components for adjusting the fuel supply conditions required by the engine (20''') can be arranged on the fuel supply line (FSL'''). Specifically, a heat exchanger (12''') and a pump (13''') can be arranged on the fuel supply line (FSL'''). The heat exchanger (12''') can adjust the temperature of the fuel to a temperature required by the engine (20'''), and the pump (13''') can compress the fuel to a pressure required by the engine (20'''). At this time, the heat exchanger (12''') can be arranged at the front end of the pump (13'''), and the pump (13''') can be arranged at the rear end of the heat exchanger (12''').

[0212] Additionally, a filter (14''') may be provided at the front end of the heat exchanger (12''') and the rear end of the pump (13'''). The filter (14''') can filter out impurities contained in the fuel, thereby preventing engine (20''') failure due to impurities.

[0213] At this time, a shut-off valve (SV) may be provided in the fuel supply line (FSL''') to block the supply of fuel through the fuel supply line (FSL'''). The shut-off valve (SV''') may be opened in a fuel supply situation and closed in a fuel supply stop situation.

[0214] In addition, a purging gas supply line (PSL''') may be connected to the fuel supply line (FSL''') between the shut-off valve (SV''') and the engine (20'''). One end of the purging gas supply line (PSL''') may be connected to the purging gas supply unit (60'''), and the other end of the purging gas supply line (PSL''') may be connected to the fuel supply line (FSL'''). The purging gas supply line (PSL''') may receive purging gas from the purging gas supply unit (60''') and transmit it to the fuel supply line (FSL''') between the shut-off valve (SV''') and the engine (20'''). When supplying purging gas through the purging gas supply line (PSL'''), the shut-off valve (SV''') can be closed, thereby moving the purging gas toward the engine (20'''), thereby removing ammonia remaining in the engine (20''') and other pipes. The purging gas can be provided as an inert gas such as nitrogen.

[0215] In a fuel supply stop situation where purging gas is supplied, a first fuel recovery line (RL1''') and a second fuel recovery line (RL2''') may be provided to recover unused fuel and purging gas from the engine (20''').

[0216] Specifically, the first fuel recovery line (RL1''') can primarily recover liquid ammonia fuel and purging gas from the engine (20''') to the separator (30'''), and the second fuel recovery line (RL2''') can secondarily recover gaseous ammonia fuel and purging gas from the engine (20''') to the fuel tank (10'''). To this end, the first fuel recovery line (RL1''') can connect the engine (20''') and the separator (30'''), and the second fuel recovery line (RL2''') can connect the engine (20''') and the fuel tank (10''').

[0217] Return valves (RV1''', RV2''') may be provided on the fuel recovery lines (RL1''', RL2'''), respectively. The return valves (RV1''', RV2''') on the fuel recovery lines (RL1''', RL2''') may be closed in a fuel supply situation and may be opened in a fuel supply stop situation. Specifically, in order to recover liquid ammonia fuel and purging gas through the first fuel recovery line (RL1''') during a fuel supply situation, the first return valve (RV1''') may be opened and the second return valve (RV2''') may be closed. Thereafter, in order to recover gaseous ammonia fuel and purging gas through the second fuel recovery line (RL2''') during a fuel supply situation, the first return valve (RV1''') may be closed and the second return valve (RV2''') may be opened.

[0218] The first fuel recovery line (RL1''') can primarily deliver liquid ammonia and purging gas to the separator (30'''). The separator (30''') can receive the liquid ammonia and purging gas through the first fuel recovery line (RL1''') and temporarily store them. However, a portion of the liquid ammonia delivered to the separator (30''') may be vaporized within the separator (30'''). Therefore, liquid ammonia, gaseous ammonia, and purging gas may be mixed and stored within the separator (30'''). At this time, as a portion of the liquid ammonia is vaporized, the internal pressure of the separator (30''') increases.

[0219] The gas recovery line (RL3''') is connected from the separator (30''') to the second fuel recovery line (RL2''') between the second return valve (RV2''') and the fuel tank (10'''), so that gaseous ammonia and purging gas in the separator (30''') can be combined into the second fuel recovery line (RL2'''). By discharging gaseous ammonia and purging gas through the gas recovery line (RL3'''), the internal pressure of the separator (30''') can be lowered. The third return valve (RV3''') is disposed on the gas recovery line (RL3''') and can be opened to lower the internal pressure of the separator (30''').

[0220] On the other hand, liquid ammonia may be stored in the separator (30'''). The liquid return line (RL4''') may merge the liquid ammonia in the separator (30''') into the fuel supply line (FSL''') in a subsequent fuel supply situation. For this purpose, the fourth return valve (RV4''') on the liquid return line (RL4''') may be closed in a fuel supply stop situation and may be opened in a fuel supply situation.

[0221] After the liquid ammonia is recovered through the first fuel recovery line (RL1'''), the second fuel recovery line (RL2''') can transfer the remaining small amount of liquid ammonia, gaseous ammonia, and purging gas to the fuel tank (10'''). The gaseous ammonia, which has a relatively large volume, can be recovered to the fuel tank (10''') through the second fuel recovery line (RL2''').

[0222] Meanwhile, in an engine emergency stop situation where ammonia fuel and purging gas remaining in the engine and pipes must be quickly recovered, the recovery process through the first fuel recovery line (RL1''') can be omitted, and the fuel and purging gas can be recovered only through the second fuel recovery line (RL2'''). As a result, ammonia fuel and purging gas remaining in the engine and pipes can be recovered within a few minutes in an emergency stop situation.

[0223] As described above, gaseous ammonia and purging gas can be recovered to the fuel tank (10''') by the fuel recovery lines (RL1''', RL2'''), the gas recovery line (RL3''') and the liquid recovery line (RL4''').

[0224] The post-treatment unit (40''') is a configuration that processes purging gas and may include a boiler. A vent line (VL) may connect the fuel tank (10''') and the post-treatment unit (40'''), and may supply the purging gas in the fuel tank (10''') to the post-treatment unit (40'''). The purging gas in the fuel tank (10''') may be delivered to the post-treatment unit (40''') through the vent line (VL) and used as fuel for the boiler.

[0225]

[0226] Operating sequence

[0227] Fig. 11 is a drawing showing the flow for primarily recovering liquid fuel and purging gas in the fuel supply system (1''') of Fig. 10. Fig. 12 is a drawing showing the flow for secondarily recovering gaseous fuel and purging gas in the fuel supply system (1''') of Fig. 10. Fig. 13 is a drawing showing the flow for processing purging gas in a fuel tank (10''') of the fuel supply system (1''') of Fig. 10.

[0228] Hereinafter, with reference to FIGS. 11 to 13, a method for processing unused fuel and purging gas in a fuel supply stop situation using the fuel supply system (1''') according to the above-described 4-1 embodiment will be described.

[0229] Although not shown in the drawing, in a fuel supply situation, ammonia fuel can be supplied from the fuel tank (10''') to the engine (20''') through the fuel supply line (FSL'''). The engine (20''') can produce propulsion power and electric power of the ship using the supplied ammonia fuel.

[0230] Meanwhile, in a fuel supply stop situation, the shut-off valve (SV) may be closed to stop the fuel supply to the engine (20'''), leaving unused ammonia fuel in the engine (20''').

[0231] As illustrated in Fig. 11, when a fuel supply stoppage situation occurs, liquid ammonia among unused ammonia fuel can be primarily recovered through the first fuel recovery line (RL1''').

[0232] Specifically, to recover liquid ammonia, purging gas may be supplied through a purging gas supply line (PSL'''), and a first return valve (RV1''') may be opened. At this time, a second return valve (RV2''') may be closed. When the first return valve (RV1''') is opened, liquid ammonia and purging gas may be delivered from the engine (20''') to the separator (30''') through the first fuel recovery line (RL1''').

[0233] At this time, a small amount of gaseous ammonia may also be delivered to the separator (30'''), and some of the liquid ammonia may be vaporized within the separator (30'''). By opening the third return valve (RV3'''), the gaseous ammonia and purging gas within the separator (30''') may merge into the second fuel recovery line (RL2'''). At this time, since the second return valve (RV2''') is closed, the gaseous ammonia and purging gas that have merged into the second fuel recovery line (RL2''') through the gas recovery line (RL3''') may be delivered to the fuel tank (10''').

[0234] Thereafter, as illustrated in FIG. 12, gaseous ammonia from the unused ammonia fuel can be secondarily recovered through the second fuel recovery line (RL2''').

[0235] Specifically, to recover gaseous ammonia, purging gas may be supplied through a purging gas supply line (PSL'''), a first return valve (RV1''') may be closed, and a second return valve (RV2''') may be opened. When the second return valve (RV2''') is opened, gaseous ammonia and purging gas among the unused ammonia fuel may be delivered to the fuel tank (10''') through a second fuel recovery line (RL2''').

[0236] In this specification, it is described that purging gas is supplied during the liquid ammonia recovery and gaseous ammonia recovery processes, respectively. However, the spirit of the present invention is not limited thereto, and purging gas may be continuously supplied during the ammonia recovery process. In this case, the liquid ammonia recovery and gaseous ammonia recovery processes can be distinguished by changing the opening and closing of the first return valve (RV1''') and the second return valve (RV2''').

[0237] Even in the gaseous ammonia recovery process as in Fig. 12, gaseous ammonia can be continuously generated within the separator (30'''), and the gaseous ammonia and purging gas within the separator (30''') can be combined with the gaseous ammonia on the second fuel recovery line (RL2''') through the gas recovery line (RL3''') and delivered to the fuel tank (10''').

[0238] Liquid ammonia in the separator (30''') is stored in the separator (30''') and, in a future fuel supply situation, can be joined to the fuel supply line (FSL) by opening the fourth return valve (RV4''') and resupplied to the engine (20''').

[0239] In addition, as shown in Fig. 13, the purging gas in the fuel tank (10''') can be delivered to the post-treatment unit (40''') through the vent line (VL) and used as fuel for the boiler.

[0240]

[0241] <Example 4-2>

[0242] Fig. 14 is a drawing illustrating a fuel supply system (100) according to the 4-2nd embodiment of the present invention. Hereinafter, the fuel supply system (100''') according to the 4-2nd embodiment will be described with reference to Fig. 14. The fuel supply system (100''') according to the 4-2nd embodiment is different from the fuel supply system (1''') according to the 4-1st embodiment in that the fuel tank (110''') must be maintained at a low pressure and a re-liquefaction system (50''') is further provided. Therefore, the differences will be mainly described, and the description and drawing symbols of the 4-1st embodiment mentioned above will be used for the same parts.

[0243] A fuel supply system (100''') according to the 4-2 embodiment of the present invention may include a fuel tank (110'''), an engine (20'''), a separator (30'''), a post-treatment unit (40'''), a re-liquefaction system (50'''), and a purging gas supply unit (60'''). In addition, as lines interconnecting components of the fuel supply system (100'''), it may include a fuel supply line (FSL'''), a first fuel recovery line (RL1'''), a second fuel recovery line (RL2'''), a gas recovery line (RL3'''), a liquid recovery line (RL4'''), a vent line (VL'''), a re-liquefaction line (RFL'''), and a purging gas supply line (PSL''').

[0244] In this embodiment, the method for recovering unused ammonia and purging gas in a fuel supply stop situation is the same as in Embodiment 4-1. However, the fuel tank (110''') of the fuel supply system (100''') according to Embodiment 4-2 may be provided as a low-pressure operating tank, which must be maintained at a low pressure. Accordingly, since the pressure inside the fuel tank (110''') is relatively low, the pressure of the fuel tank (110''') may increase as the recovered gaseous ammonia flows in, and thus a re-liquefaction system (50''') may be provided. In addition, as heat is continuously transferred to the inside of the fuel tank (110'''), boil-off gas may be generated inside the fuel tank (110'''). The re-liquefaction system (50''') may process the gaseous ammonia and boil-off gas recovered by the fuel tank (110'''). The presence or absence of a re-liquefaction system (50''') as in Example 4-2 may vary depending on the operating pressure of the fuel tank, and does not limit the technical concept of the present invention. Hereinafter, for convenience of explanation, both recovered gaseous ammonia and evaporated gas are collectively referred to as "gaseous ammonia."

[0245] A re-liquefaction system (50''') may be provided on a vent line (VL'''). Gaseous ammonia and purging gas within a fuel tank (110''') may be discharged from the fuel tank (110''') through the vent line (VL'''). At least a portion of the gaseous ammonia delivered through the vent line (VL''') may be re-liquefied by the re-liquefaction system (50''').

[0246] Specifically, the re-liquefaction system (50''') may be provided with a configuration such as a heat exchanger, a compressor, and a condenser, and gaseous ammonia may be re-liquefied through processes such as compression and condensation. Gaseous ammonia delivered through the vent line (VL''') may be re-liquefied by the re-liquefaction system (50'''), and then delivered back to the fuel tank (110''') through the re-liquefaction line (RFL), and stored in the fuel tank (110''').

[0247] In addition, the purging gas delivered through the vent line (VL''') is delivered to the post-treatment unit (40''') and can be used as fuel for the boiler in the post-treatment unit (40''').

[0248]

[0249] Fuel recovery method

[0250] Figure 15 is a drawing of a fuel recovery method using a fuel supply system (1''', 100''') according to the present invention. The fuel recovery method of the present invention can recover fuel in different ways in normal stop situations and emergency stop situations, respectively. In particular, the fuel recovery method of the present invention aims to quickly recover ammonia remaining in the engine (20''') and piping in an emergency stop situation.

[0251] Here, a normal stop situation may refer to a situation in which the ammonia fuel supply is interrupted due to a fuel change of the engine (20''') or a stop of the engine (20'''), or a situation in which ammonia remaining in the engine (20''') and each pipe must be discharged for maintenance. On the other hand, an emergency stop situation may refer to a situation in which the engine (20''') must be urgently stopped to prevent a bigger accident in a dangerous situation, such as when it is determined that there is a problem with the engine (20''').

[0252] The fuel recovery method of the present invention may include a purging gas supply step (S10''') for supplying purging gas, an emergency stop situation determination step (S20''') for determining whether an emergency stop situation exists, a first fuel recovery step (S30''') for recovering fuel to a separator (30''') through a first fuel recovery line (RL1'''), and a second fuel recovery step (S40''') for recovering fuel to a fuel tank (10''', 110''') through a second fuel recovery line (RL2''').

[0253] In a normal stop situation, the purging gas supply step (S110'''), the first fuel recovery step (S30'''), and the second fuel recovery step (S40''') can be performed. On the other hand, in an emergency stop situation, the purging gas supply step (S110''') and the second fuel recovery step (S40''') can be performed.

[0254] In both normal stop and emergency stop situations, in the purging gas supply stage (S110'''), purging gas can be supplied through the purging gas supply line (PSL''') to recover ammonia fuel remaining in the engine (20''') and piping.

[0255] In the emergency stop situation determination step (S20'''), it can be determined whether or not an emergency stop situation exists. If it is not an emergency stop situation, it can be considered a normal stop situation. In this specification, the emergency stop situation determination step (S20''') is described and illustrated in the drawings as being performed after the purging gas supply step (S110'''), but the spirit of the present invention is not limited thereto. As another example, it can be determined whether a normal stop situation or an emergency stop situation exists before the purging gas is supplied.

[0256] In the emergency stop situation judgment step (S20'''), if it is determined to be a normal stop situation, the first fuel recovery step (S30''') and the second fuel recovery step (S40''') may be performed. Although not shown in the drawing, in this case, the purging gas supply step (S110''') may be performed again between the first fuel recovery step (S30''') and the second fuel recovery step (S40'''). Accordingly, after the liquid ammonia and the purging gas are recovered to the separator (30''') through the first fuel recovery line (RL1'''), a small amount of the liquid ammonia, the gaseous ammonia, and the purging gas may be recovered to the fuel tanks (10''', 110''') through the second fuel recovery line (RL2''').

[0257] On the other hand, in the emergency stop situation judgment step (S20'''), if an emergency stop situation is determined, the first fuel recovery step (S30''') is omitted, and only the second fuel recovery step (S40''') can be performed. Accordingly, liquid ammonia, gaseous ammonia, and purging gas can be recovered to the fuel tanks (10''', 110''') at once through the second fuel recovery line (RL2''').

[0258] The fuel recovery method of the present invention can quickly recover fuel and purging gas remaining in the engine (20''') and pipes into the fuel tank (10''', 110''') within a few minutes in an emergency stop situation, thereby preventing a larger accident.

[0259]

[0260] Example 4-3

[0261] Fig. 16 is a drawing illustrating a fuel supply system (1000''') according to the 4-3 embodiment of the present invention. Hereinafter, the fuel supply system (1000''') according to the 4-3 embodiment will be described with reference to Fig. 16. The fuel supply system (1000''') according to the 4-3 embodiment is different from the fuel supply system (1''') according to the 4-1 embodiment in that a separator (30''') is not provided and only one fuel recovery line is provided. Therefore, the differences will be mainly described, and the description and drawing symbols of the 4-1 embodiment mentioned above will be used for the same parts.

[0262] A fuel supply system (1000''') according to the 4-3 embodiment of the present invention may include a fuel tank (10'''), an engine (20'''), a post-processing unit (40'''), and a purging gas supply unit (60'''). In addition, as lines interconnecting components of the fuel supply system (1000'''), it may include a fuel supply line (FSL'''), a fuel recovery line (RL'''), a vent line (VL'''), and a purging gas supply line (PSL''').

[0263] In this embodiment, unused ammonia can be delivered to the fuel tank (10''') through the fuel return line (RL) without distinction between liquid and gas.

[0264] Specifically, in a fuel supply stop situation, purging gas can be supplied through the purging gas supply line (PSL'''). At this time, the shut-off valve (SV''') can be closed, and the return valve (RV''') on the fuel return line (RL''') can be opened. Accordingly, unused fuel and purging gas can be delivered to the fuel tank (10''') through the fuel return line (RL''').

[0265] Additionally, the purging gas in the fuel tank (10''') can be delivered to the post-treatment unit (40''') through the vent line (VL''') and used as fuel for the boiler.

[0266] In Fig. 16, the fuel tank (10''') is illustrated as being a pressurized tank identical to that of the 4-1 embodiment, but the spirit of the present invention is not limited thereto. In the 4-3 embodiment, the fuel tank (10''') may also be provided as a low-pressure operating tank identical to that of the fuel tank (110''') of the 4-2 embodiment. However, in this case, a re-liquefaction system for processing gaseous ammonia and evaporated gas may be provided on the vent line (VL'''). That is, whether or not the re-liquefaction system is provided may vary depending on the operating pressure of the fuel tank, and does not limit the technical spirit of the present invention.

[0267]

[0268] The fuel supply system (1''', 100'', 1000''') according to the present invention can recover gaseous ammonia and purging gas into the fuel tank (10''', 110'''). Specifically, the present invention intends to utilize the fuel tank (10''', 110''') as a buffer tank without separately providing a conventional buffer tank for storing gaseous ammonia and purging gas having a relatively large volume. Accordingly, there is an advantage in that the space occupied by the fuel supply system (1''', 100'', 1000''') can be reduced compared to the conventional technology that uses a large-capacity buffer tank.

[0269]

[0270] The above description is merely an illustrative illustration of the technical idea of ​​the present invention, and those skilled in the art will appreciate that various modifications and variations can be made without departing from the essential characteristics of the present invention. Therefore, the embodiments disclosed in the present invention are intended to illustrate rather than limit the technical idea of ​​the present invention, and the scope of the technical idea of ​​the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the following claims, and all technical ideas within a scope equivalent thereto should be interpreted as being included in the scope of the rights of the present invention.

Claims

1. Fuel supply line that supplies fuel from the fuel tank to the engine; In a fuel supply stop situation, a purging gas supply line connected to the fuel supply line and supplying purging gas; A separator that receives and stores unused fuel and purging gas from the engine; A first fuel recovery line provided to primarily recover unused fuel and purging gas from the engine to the separator; A second fuel recovery line provided to secondarily recover unused fuel and purging gas from the engine to the fuel tank; A gas recovery line provided to combine gaseous fuel and purging gas from the separator into the second fuel recovery line; and A fuel supply system comprising a liquid recovery line arranged to join liquid fuel from the separator to the fuel supply line.

2. In claim 1, A fuel supply system further comprising a vent line for supplying purging gas within the fuel tank to a post-treatment unit.

3. In claim 2, A fuel supply system wherein the above fuel tank is provided as a pressurized tank.

4. In claim 2, The above fuel tank is provided as a low-pressure operating tank, fuel supply system.

5. In claim 4, Further comprising a re-liquefaction system provided on the above vent line, A fuel supply system wherein the vent line discharges gaseous fuel together with purging gas from the fuel tank, and at least a portion of the gaseous fuel delivered through the vent line is reliquefied by the reliquefaction system and delivered to the fuel tank.

6. In claim 2, The above post-processing unit is a fuel supply system including a boiler that uses the purging gas delivered through the vent line as fuel.

7. Fuel supply line that supplies fuel from the fuel tank to the engine; In a fuel supply stop situation, a purging gas supply line connected to the fuel supply line and supplying purging gas; A fuel recovery line for transferring unused fuel and purging gas from the engine to the fuel tank; and A fuel supply system including a vent line for supplying purging gas within the fuel tank to a post-treatment unit.

8. A method for recovering fuel using a fuel supply system according to any one of claims 1 to 6, Purging gas supply step for supplying purging gas; A first fuel recovery step for recovering unused fuel and purging gas to a separator through a first fuel recovery line; and A second fuel recovery step is included to recover unused fuel and purging gas to the fuel tank through a second fuel recovery line, In a normal stop situation, the purging gas supply step, the first fuel recovery step and the second fuel recovery step are performed, A fuel recovery method, wherein the purging gas supply step and the second fuel recovery step are performed in an emergency stop situation.

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