VOC fuel supply system and vessel equipped with same

Abstract

The present invention relates to a volatile organic compound (VOC) fuel supply system and method for supplying VOCs to an engine fuel, and to a VOC-fueled ship. The VOC fuel supply system according to the present invention includes an engine that uses gas as fuel and operates in a gas fuel mode; a VOC supply unit that supplies volatile organic compounds (VOCs) as fuel to the engine; a fuel supply line that connects the VOC supply unit to the engine and is a path for transporting gaseous VOC fuel from the VOC supply unit to the engine; and a drain filter that is installed in the fuel supply line and filters out re-condensed VOCs in liquid state contained in the VOC fuel upstream of the engine.

Description

[Technical field]

[0001] The present invention relates to a volatile organic compound (VOC) fuel supply system and method for supplying VOCs as a fuel to an engine, and to a ship that uses VOCs as a fuel. [Background technology]

[0002] Volatile organic compounds (VOCs) are soot produced by the evaporation of liquid oil from oil storage tanks installed on oil tankers that store crude oil cargoes, or from fuel oil storage tanks that store fuel oil used as engine fuel.

[0003] The composition of VOCs includes almost all of the components of the oil stored in the storage tank, i.e., organic compounds. When VOCs are released into the atmosphere, they react photochemically with nitrogen oxides in the presence of sunlight to produce ozone and photochemical oxidants, which cause environmental pollution such as photochemical smog, ozone layer destruction, and greenhouse effect. In addition, substances such as benzene are carcinogenic and therefore extremely harmful to the human body.

[0004] Due to the harmful nature of VOCs, the International Maritime Organization and other organizations have imposed some restrictions on VOC emissions at some ports. Furthermore, since releasing VOCs into the atmosphere is a loss of useful substances, it is necessary to devise methods to capture and effectively treat VOCs rather than releasing them into the atmosphere. In recent years, research has also been conducted to improve the energy efficiency of ships by applying technology to recycle VOCs as fuel oil.

[0005] Because VOCs contain a high content of heavy hydrocarbons and do not meet the methane number requirements of gas engines, the only option up until now has been to use a reformer to convert VOCs into methane, a light hydrocarbon, before supplying it to gas engines.

[0006] Fuel supply using a reformer has problems in that it requires periodic maintenance to maintain the performance of the reformer, and that a large amount of thermal energy such as steam is required for the reforming reaction, making additional fuel combustion necessary. Summary of the Invention [Problem to be solved by the invention]

[0007] The present invention overcomes the above-mentioned problems and provides a VOC fuel supply system and method for stably supplying VOCs as engine fuel, and a ship that uses VOCs as fuel. [Means for solving the problem]

[0008] In one embodiment of the present invention to achieve the above object, a VOC fuel supply system is provided, comprising: an engine that uses gas as fuel; a VOC supply unit that supplies volatile organic compounds (VOCs) as fuel to the engine; a fuel supply line that connects the VOC supply unit to the engine and is a path for transporting gaseous VOC fuel from the VOC supply unit to the engine; and a drain filter that is provided in the fuel supply line and filters liquid-state recondensed VOCs contained in the VOC fuel from upstream of the engine.

[0009] Preferably, the drain filter includes a funnel-shaped hopper provided at a lower portion, and a gas inlet pipe provided at an upper portion, one end of which extends from the fuel supply line and the other end of which is bent toward the hopper, for injecting the VOC fuel into the drain filter. Liquid recondensed VOCs contained in the VOC fuel are collected under the hopper, and only the gaseous VOC fuel from which the liquid recondensed VOCs have been separated is discharged.

[0010] Preferably, the engine further includes a gas supply unit that supplies to the engine a gas fuel with a higher calorific value than the VOC, and a fuel mixing unit that supplies to the engine a mixed gas fuel that is a mixture of the gas fuel supplied from the gas supply unit and the VOC fuel supplied from the VOC supply unit, and the engine is supplied with the mixed gas fuel as the gas fuel.

[0011] Preferably, the device may further comprise a recondensed VOC recycling means for recovering recondensed VOCs in a liquid state collected by the drain filter.

[0012] Preferably, the recondensation VOC recycling means may further include a fuel temperature measuring unit provided in the fuel supply line upstream of the drain filter for measuring the temperature of the gas fuel supplied to the engine, and a control unit for stopping operation of the VOC supply unit when the temperature measurement value of the fuel temperature measuring unit becomes lower than a preset temperature.

[0013] Preferably, the recondensation VOC recycle means may include a level measurement unit that measures the water level in the drain filter; a filter shutoff valve for shutting off the flow of fluid from the drain filter to the engine; a vent valve between the filter shutoff valve and the engine, and for venting gas fuel from the engine; and a control unit that stops operation of the VOC supply unit, closes the filter shutoff valve, and opens the vent valve when the water level measurement value by the level measurement unit reaches a predetermined water level.

[0014] Preferably, the recondensed VOC recycling means may include an LVOC recovery valve that discharges recondensed VOCs in liquid state collected by the drain filter; an LVOC recovery tank that stores the recondensed VOCs discharged from the drain filter; and an LVOC transfer pump that supplies the recondensed VOCs stored in the LVOC recovery tank to a VOC supply section.

[0015] Preferably, the recondensed VOC recycling means may further include an inert gas supply unit that supplies an inert gas to the drain filter to discharge the recondensed VOCs collected by the drain filter from the drain filter.

[0016] Preferably, the recondensed VOC recycling means includes a double shutoff valve unit for shutting off between the VOC supply unit and the drain filter when inert gas is supplied to the drain filter; a filter shutoff valve for shutting off between the drain filter and the engine when inert gas is supplied to the drain filter; a fuel pressure measurement unit for measuring the pressure of the fluid supplied to the drain filter from the fuel supply line; an LVOC recovery valve for discharging recondensed VOCs in liquid state collected by the drain filter; and a control unit for opening the LVOC recovery valve when the pressure measurement value of the fuel pressure measurement unit reaches a predetermined pressure.

[0017] Preferably, the double shutoff valve unit includes a valve that adjusts the pressure of the fluid passing through the double shutoff valve unit, and the control unit controls the opening of the double shutoff valve unit so that the pressure measurement value of the fuel pressure measurement unit does not exceed a preset pressure change rate, and adjusts the pressure of the inert gas supplied to the drain filter.

[0018] In order to achieve the above object, in another embodiment of the present invention, a ship using VOCs as fuel is provided, the ship being equipped with the above VOC supply system.

[0019] Preferably, the ship comprises an inert gas supply unit that generates inert gas and supplies the inert gas to inert gas demanders on board the ship; an inert gas supply line that connects the inert gas supply unit to the fuel supply line; a purge shutoff valve unit that is provided in the inert gas supply line and controls the flow of inert gas to the fuel supply line; and a gas shutoff valve unit that is provided in the fuel supply line upstream of the point where the inert gas supply line is connected and controls the flow of fuel to the engine; the drain filter is provided downstream of the gas shutoff valve unit, and recondensed VOCs collected by the drain filter are discharged from the drain filter by the pressure of the inert gas under the control of a purge shutoff valve unit and a gas shutoff valve unit that are provided on the ship.

[0020] Preferably, the ship may further include an LVOC recovery tank provided in an open space on the upper deck of the ship for storing recondensed VOCs discharged from the drain filter; and an LVOC transfer pump for supplying the recondensed VOCs stored in the LVOC recovery tank to the VOC supply unit so as to supply the recondensed VOCs as fuel for the engine.

[0021] In order to achieve the above object, in yet another embodiment of the present invention, there is provided a VOC fuel supply method comprising the steps of: adjusting volatile organic compounds (VOCs) at a temperature and pressure required by an engine to produce a gaseous VOC gas fuel; passing the gaseous VOC gas fuel through a drain filter before supplying it to the engine; and supplying the VOC gas fuel that has passed through the drain filter to the engine; in which, by passing the gaseous VOC gas fuel through the drain filter, liquid-state recondensed VOCs that have condensed during the process of supplying the fuel at the temperature and pressure required by the engine are separated, and only the gaseous VOC gas fuel is supplied to the engine.

[0022] Preferably, the step of generating the gaseous VOC gas fuel may include the step of: mixing the VOC with a gas fuel having a higher calorific value than the VOC to generate a mixed gas fuel.

[0023] Preferably, the method may further include a step of discharging the recondensed VOCs in liquid state separated by the drain filter, and a recycling step of supplying the discharged recondensed VOCs to the step of generating the VOC gas fuel in gas state.

[0024] Preferably, the step of discharging the recondensed VOCs may include a step of measuring the temperature of the VOC gas fuel upstream of the drain filter, and a step of stopping the VOC fuel supply before discharging the recondensed VOCs if the temperature measurement value measured in the step of measuring the temperature is lower than a predetermined temperature.

[0025] Preferably, the step of discharging the recondensed VOCs may include a step of measuring a water level in the drain filter, and a VOC fuel vent step of stopping the process of supplying the recondensed VOCs to the engine before discharging the recondensed VOCs and venting VOC gas fuel from the drain filter and the engine when the water level measurement value measured in the water level measurement step reaches a predetermined water level.

[0026] Preferably, the step of discharging the recondensed VOCs includes the steps of: blocking the upstream and downstream of the drain filter; and supplying an inert gas to the drain filter whose upstream and downstream are blocked; and the recondensed VOCs can be discharged from the drain filter by the pressure of the inert gas.

[0027] Preferably, the step of supplying the inert gas may further include a step of measuring the pressure upstream of the drain filter, and a pressure adjustment step of adjusting and supplying the pressure of the inert gas such that the pressure measurement value measured in the pressure measuring step does not exceed a preset pressure change rate.

[0028] In order to achieve the above object, in another embodiment of the present invention, there is provided a VOC fuel supply system comprising: an engine that uses gas as fuel and operates in a gas fuel mode; a VOC supply unit that supplies volatile organic compounds (VOCs) as fuel to the engine; a fuel supply line that connects the VOC supply unit to the engine and transfers gaseous VOC fuel from the VOC supply unit to the engine; a cooling line through which a heat medium circulates to cool the fuel supply line and condense gaseous VOCs remaining in the fuel supply line; a cooling valve provided in the cooling line; and a control unit that controls the cooling valve to open when the gas fuel mode is stopped.

[0029] Preferably, the system includes a reducing agent tank for storing a reducing agent for denitrifying exhaust gas discharged from the engine; and a chiller unit for circulating a heat medium for maintaining the temperature of the reducing agent tank, and the cooling line branches off from a line through which the heat medium, which has been heated to a high temperature after cooling the reducing agent tank, is recirculated to the chiller unit, and is connected to an end of the fuel supply line.

[0030] Preferably, the system further includes an inert gas supply unit that supplies an inert gas to the fuel supply line to discharge LVOC in a liquid state remaining in the fuel supply line; an LVOC purge line that connects the inert gas supply unit and the fuel supply line; an LVOC purge valve provided in the LVOC purge line; and a purge temperature measurement unit that measures the temperature of the fuel supply line, and the control unit controls the LVOC purge valve to open when the temperature measurement value of the purge temperature measurement unit reaches a preset value, so that the inert gas is supplied to the fuel supply line and the LVOC is discharged from the fuel supply line by the inert gas.

[0031] Preferably, the system further includes a drain filter for temporarily storing the inert gas and LVOC discharged from the fuel supply line; a fourth vent line for transporting the gas discharged from the drain filter; a VOC vent valve provided in the fourth vent line; an LVOC recovery line for transporting the liquid discharged from the drain filter; an LVOC recovery valve provided in the LVOC recovery line; and a fuel pressure measurement unit for measuring the pressure of the fuel supply line; and the control unit opens the VOC vent valve and the LVOC recovery valve when the pressure measurement value of the fuel pressure measurement unit reaches a preset set value.

[0032] Preferably, the drain filter includes a funnel-shaped hopper provided at a lower portion, and a gas inlet pipe provided at an upper portion, one end of which extends from the fuel supply line and the other end of which is bent toward the hopper, for injecting the VOC fuel into the drain filter. Liquid recondensed VOCs contained in the VOC fuel are collected under the hopper, and only the gaseous VOC fuel from which the liquid recondensed VOCs have been separated is discharged.

[0033] Preferably, the system may further include an LVOC recovery tank for storing the LVOC discharged through the LVOC recovery line, and an LVOC transfer pump for supplying the recondensed VOC stored in the LVOC recovery tank to the VOC supply section.

[0034] Preferably, the system further includes a fuel temperature measuring unit that measures the temperature of the gas fuel supplied to the engine, and the control unit stops operation of the VOC supply unit when the temperature measurement value of the fuel temperature measuring unit becomes lower than a preset temperature.

[0035] In order to achieve the above object, in yet another embodiment of the present invention, there is provided a ship that uses VOCs as fuel and is equipped with the VOC fuel supply system.

[0036] Furthermore, in order to achieve the above object, in yet another embodiment of the present invention, there is provided a VOC fuel supply method comprising the steps of: supplying volatile organic compounds (VOCs) to an engine as gas fuel to operate in a gas fuel mode, and when the gas fuel mode is stopped, blocking a fuel supply line that transfers the gas fuel to the engine; and supplying a heat medium to the fuel supply line to condense gaseous VOCs remaining in the fuel supply line.

[0037] Preferably, the method further comprises the steps of: measuring a temperature of the fuel supply line; and, when the temperature of the fuel supply line reaches a preset value, supplying an inert gas to the fuel supply line to drain LVOC from the fuel supply line and collect it in a drain filter.

[0038] Preferably, the method includes the steps of: measuring the pressure in the fuel supply line; discharging gas from the drain filter when the pressure in the fuel supply line reaches a preset value; and discharging liquid from the drain filter and storing it in an LVOC recovery tank when the pressure in the fuel supply line reaches a preset value, and the LVOC stored in the LVOC recovery tank is used as fuel for the engine. Effect of the Invention

[0039] The VOC fuel supply system and method, and the ship that uses VOC as fuel according to the present invention, can use VOC as engine fuel without releasing it into the atmosphere, thereby preventing environmental pollution and improving the energy efficiency of the ship.

[0040] When VOCs are supplied as engine fuel, if they are compressed to meet the pressure conditions required by the engine, the dew point of the VOCs becomes high and they can be condensed even at room temperature. However, if condensed liquid VOCs flow into an engine operating in gas fuel mode, problems may occur with engine combustion. The present invention safely separates condensed liquid VOCs from gas fuel before supplying them to the engine, preventing problems that may occur when condensed liquid VOCs are supplied to an engine operating in gas fuel mode.

[0041] In addition, when gas fuel mode operation is stopped or switched to another fuel mode, the present invention can cool and recover VOCs remaining in a gaseous state in the piping, and recycle the condensed liquid VOCs as fuel.

[0042] Furthermore, the present invention can recover liquid VOCs that have been separated from the gas fuel before it is supplied to the engine, and recycle them as engine fuel.

[0043] In addition, it simplifies the configuration of VOC recovery and recycling processes and equipment by making maximum use of existing components that are essential for a ship's or engine's fuel supply system. [Brief description of the drawings]

[0044] [Figure 1] 1 is a simplified diagram showing a portion of a ship equipped with a VOC fuel supply system according to a first embodiment of the present invention. FIG. [Diagram 2] FIG. 10 is a simplified diagram showing a portion of a ship equipped with a VOC fuel supply system according to a second embodiment of the present invention. [Diagram 3] FIG. 11 is a diagram for explaining the flow of fluid through which gas fuel is supplied to an engine when the VOC fuel supply system according to the second embodiment of the present invention operates in a gas fuel mode. [Figure 4] FIG. 11 is a diagram illustrating the flow of a fluid for purging a pipe when the VOC fuel supply system according to the second embodiment of the present invention is operated in a fuel switching mode. [Diagram 5]FIG. 11 is a diagram illustrating the flow of fluid for treating VOCs collected in a drain filter after purging of piping when the VOC fuel supply system according to the second embodiment of the present invention is operated in a fuel switching mode. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

[0045] For a full understanding of the operating advantages and objects attained by the embodiments of the present invention, reference should be had to the accompanying drawings, in which preferred embodiments of the invention are illustrated.

[0046] The configuration and operation of the preferred embodiment of the present invention will be described in detail below with reference to the accompanying drawings. Note that when referring to the components in each drawing, the same components are denoted by the same reference numerals as much as possible even if they are shown in different drawings. Note that the following embodiment can be modified in various ways, and the scope of the present invention is not limited by the following examples.

[0047] The VOC fuel supply system and method according to one embodiment of the present invention will be described below using an example of application to a ship, but can also be applied on land.

[0048] In addition, the embodiments of the present invention described below will be described with reference to an example of application to a crude oil carrier or crude oil tanker that transports produced crude oil as cargo. However, the present invention can be applied to all ships or offshore floating structures equipped with oil storage tanks, such as floating production, storage and offloading units (FPSOs) that produce crude oil at sea, product carriers that transport petroleum products, and floating storage units (FSUs) that can store produced crude oil, which generate VOCs and pose environmental hazards, and which have dual-fuel engines that use both fuel oil and gas fuel.

[0049] Furthermore, the ship in one embodiment of the present invention described below may be a liquefied gas fueled ship (LFS) that uses liquefied gas as gas fuel.

[0050] Here, the liquefied gas is a substance with a higher calorific value than VOCs and may be a substance containing methane or ethane. For example, it may be a hydrocarbon-based liquefied gas fuel such as LNG (Liquefied Natural Gas), LEG (Liquefied Ethane Gas), LPG (Liquefied Petroleum Gas), or liquefied ethylene gas, or it may be ammonia (NH 3 ), hydrogen (H 2 ) or non-hydrocarbon liquefied gas fuels.

[0051] However, in the embodiments described below, the use of LNG as a gas fuel for an engine will be described as an example, and boil-off gas (BOG) produced by the natural evaporation of LNG or natural gas produced by vaporizing LNG can be used as engine fuel alone or mixed with VOCs.

[0052] In addition, the engine in one embodiment of the present invention described below may be a dual-fuel engine that can use fuel oil and natural gas selectively or in combination, and may include one or more of a high-pressure gas injection engine, a medium-pressure gas injection engine, and a low-pressure gas injection engine.

[0053] DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS A VOC fuel supply system and method according to an embodiment of the present invention, and a ship that uses VOC as fuel, will be described below with reference to FIGS.

[0054] Referring to FIG. 1, the VOC fuel supply system of the first embodiment of the present invention includes an engine 500, a VOC supply unit that adjusts volatile organic compounds (VOCs) to the pressure and temperature conditions required by the engine 500 and supplies the VOC gas fuel to the engine 500, a gas supply unit that adjusts and supplies gas fuel having a higher calorific value than the VOCs to the pressure and temperature conditions required by the engine 500, and a fuel mixing unit 400 that mixes the VOCs and the gas fuel to generate mixed gas fuel.

[0055] The engine 500 of this embodiment is a dual fuel engine that can selectively use gas and oil as fuel, and operates in a gas fuel mode using gas fuel as fuel and an oil fuel mode using oil (fuel oil) as fuel.

[0056] The VOC fuel supply system and method of the present embodiment supplies gas fuel as fuel to the engine 500 when the engine 500 operates in a gas fuel mode. When the engine 500 operates in the gas fuel mode, any one of natural gas, VOCs, and a mixed gas fuel of a mixture of natural gas and VOCs is supplied as the gas fuel, but the present embodiment will be described on the basis that the engine 500 operates in the gas fuel mode and is supplied with mixed gas fuel as fuel.

[0057] In addition, the engine 500 in this embodiment includes at least one of a main engine for propelling the vessel and a generator engine for generating electricity, and at least one is provided. In the figure, two engines 500 are provided as an example.

[0058] Meanwhile, the engine 500 must be installed in an engine room ER, which is classified as a dangerous zone according to ship safety regulations. The engine room ER is located under the upper deck of the ship.

[0059] When the engine 500 is a gas-fueled engine, the gas piping (fuel supply line FL) passing through the engine room ER must be constructed of a double wall pipe 510.

[0060] For ease of explanation, in the following, of the fuel supply line FL, the section provided with double pipe 510 will be referred to as double pipe 510, and the section that is not double pipe 510 will be referred to as fuel supply line FL.

[0061] The double pipe 510 may be installed to extend to the internal combustion chamber of the engine 500, and the mixed fuel transferred from the fuel mixing unit 400 through the fuel supply line FL flows through the double pipe 510 and is injected into the combustion chamber of the engine 500.

[0062] Meanwhile, gas fuel that is not injected into the combustion chamber of the engine 500 and is recovered, or gas fuel that must be discharged when a problem occurs in the engine 500, such as gas tripping, can be vented to a vent mast through a first vent line VL1 connected from the engine 500 to the vent mast. A vent valve 520 that operates to vent or purge the fluid filled in the engine 500 and the double pipe 510 by opening and closing control can be provided in the first vent line VL1.

[0063] The space between the inner pipe and the outer pipe of the double pipe 510, i.e. the outer pipe, needs to be filled with air to prevent various accidents that may occur when gas leaks from the inner pipe, and it is prescribed that ventilation work be performed to periodically replace the air filled in the outer pipe.

[0064] The safety regulations for gas-fueled ships (IGF code; International Code of Safety for Ships using Gases or other Low-flashpoint Fuels) stipulate that ventilation work for the double pipe 510 should be performed 30 times per hour (so-called 30 air change rule). By performing ventilation work, even if gas leaks from the inner pipe to the outer pipe, the gas is discharged to the outside together with the ventilating air, and the danger caused by gas leakage can be prevented.

[0065] In addition, in order to supply fuel to the engine 500, a gas valve unit (GVU) room GR used to control the fuel supply is installed, and is also located below the upper deck, adjacent to the engine room ER in the danger zone.

[0066] Since the GVU room GR is also located adjacent to the engine room ER, which is a hazardous area, ventilation work must be carried out to exchange the internal air in the GVU room GR 30 times per hour.

[0067] It is stipulated that ventilation air shall be taken from areas classified as open safety areas, such as cargo areas, and used by suction.

[0068] Therefore, on the ship, a damper 720 is provided to draw in outside air from a location defined as a non-hazardous open area under shipboard regulations, such as the cargo space, as ventilation air to be supplied to the double pipe 510 and the GVU room GR, and an exhaust duct 710 and a ventilation fan 700 are provided to exhaust the internal air in the double pipe 510 and the GVU room GR to the outside.

[0069] The damper 720 may be provided with a flame screen to prevent the spread of flames in the event of a fire.

[0070] The VOC supply unit of this embodiment may include a VOC compressor 230 that compresses VOCs transferred from a cargo tank 100 that stores fuel oil or crude oil, a cooling unit 240 that cools the heat of compression obtained when the VOCs are compressed in the VOC compressor 230, a condenser 250 that liquefies the VOCs compressed in the VOC compressor 230, an LVOC tank 200 that stores the liquid VOCs, i.e., LVOC, produced by condensing the compressed VOCs in the condenser 250, an LVOC vaporizer 220 that vaporizes the LVOC discharged from the LVOC tank 200 and supplies it as fuel for the engine 500, and an LVOC supply pump 210 that discharges the LVOC to be supplied as fuel for the engine 500 from the LVOC tank 200 and transfers it to the LVOC vaporizer 220.

[0071] In addition, the gas supply unit of this embodiment may include a fuel tank 300 that stores gas fuel to be supplied to the engine 500, an LNG vaporizer 320 that vaporizes liquefied natural gas (LNG) discharged from the fuel tank 300, a fuel supply pump 310 that discharges the LNG to be supplied as fuel for the engine 500 from the fuel tank 300 and transfers it to the LNG vaporizer 320, and a BOG heater 330 that adjusts the evaporated gas BOG transferred from the fuel tank 300 to the temperature required by the engine 500.

[0072] The gas fuel can be stored in a liquid state, i.e., LNG state, in the fuel tank 300 of this embodiment. Also, the fuel tank 300 of this embodiment can be a pressurized type pressure tank that is operated under a pressure higher than normal pressure.

[0073] The fuel mixing unit 400 of the present embodiment can mix the VOCs transferred from the VOC supply unit and the natural gas transferred from the gas supply unit and supply the mixed gas to the engine 500 .

[0074] Although VOCs or gas fuel can be supplied alone as the fuel for the engine 500, VOCs have a low calorific value, and therefore the efficiency of combustion decreases when supplied alone as the gas fuel for the engine 500. In this embodiment, a fuel mixing unit 400 is provided to mix VOCs with natural gas and supply the mixed gas fuel as the fuel for the engine 500.

[0075] In the fuel mixing section 400, the VOCs vaporized in the LVOC vaporizer 220 and the natural gas vaporized in the LNG vaporizer 320 are mixed, and if necessary, evaporated gas heated by the BOG heater 330 can be further mixed.

[0076] The mixed gas fuel of VOC and natural gas mixed in the fuel mixing section 400 is supplied as fuel to the engine 500 via a fuel supply line FL that connects the fuel mixing section 400 and the engine 500 .

[0077] In this embodiment, the VOC supply unit, the gas supply unit, and the fuel mixing unit 400 may be provided at the top of the upper deck of the ship, and the engine 500 may be provided in a separate engine room ER provided at the bottom of the upper deck. In this case, the fuel supply line FL connected from the fuel mixing unit 400 to the engine 500 is provided passing through the top of the upper deck (first section), the inside of the GVU room GR (second section), and the inside of the engine room ER (third section) in this order. At this time, since the first section is exposed to the outside air, the fuel supply line FL provided in the first section may be thermally insulated, and the fuel supply line FL provided in the third section may be provided as a double pipe 510 according to safety regulations.

[0078] In this embodiment, the mixed gas fuel can contain a maximum of about 25% VOCs and about 75% natural gas, but the mixture ratio of VOCs and natural gas can be adjusted according to the load of the engine 500. When the load of the engine 500 increases, the mixture ratio can be adjusted to respond to the increase in the load of the engine 500 by increasing the mixture ratio of natural gas and decreasing the mixture ratio of VOCs from the above mixture ratio.

[0079] On the other hand, VOCs exist in a gaseous state under atmospheric pressure, but when compressed to the pressure required by the engine 500, their dew point becomes high, and they have the property of condensing even at room temperature unless additional heating is applied.

[0080] For example, the dew point of VOCs at 10 bar is about 25° C. In other words, if the engine 500 is a power generation engine that requires a gas fuel pressure of about 10 bar, and the VOC supply unit is designed to compress the VOCs at 10 bar, the VOCs compressed at 10 bar will condense in a liquid state when the environment becomes 25° C. or lower during the process of being supplied to the engine 500.

[0081] That is, in order to use VOCs as fuel for engine 500, the pressure and temperature of the VOCs must be maintained at the levels required by engine 500, but if the temperature of the VOCs falls below the dew point temperature, the VOCs will condense.

[0082] In addition, even if VOCs and natural gas are mixed in the fuel mixing section 400, it is impossible to achieve a completely uniform chemical composition, so there is a possibility that some VOCs may condense at low temperatures in the VOC-natural gas mixed gas fuel.

[0083] If such condensed VOCs enter the engine 500 in a liquid state, it can cause various accidents such as misfiring and explosions.

[0084] In order to vaporize the recondensed VOCs, they must be heated to approximately 90° C. or higher at 6 bar. In other words, even if the recondensed VOCs do not flow into the engine 500, unless a means for heating the recondensed VOCs is added, the recondensed VOCs will remain in the fuel supply line FL without being vaporized.

[0085] In this embodiment, the fuel may further include a recondensed VOC recycling means for separating recondensed VOCs in liquid state that are condensed during the process of being supplied from the fuel mixing section 400 to the engine 500 and mixed into the mixed gas fuel so that they are not supplied to the engine 500, removing the recondensed VOCs in liquid state separated from the mixed gas fuel from the fuel supply line FL, recovering the removed recondensed VOCs, and recycling them again in the fuel for the engine 500.

[0086] That is, the recondensation VOC recycling means of this embodiment must be applied to a ship that uses VOCs as fuel for the engine 500 or a fuel supply system that supplies VOCs as fuel for the engine 500 .

[0087] The recondensed VOC recycling means of this embodiment is provided in the fuel supply line FL and may include a fuel temperature measuring unit 410 that measures the temperature of the mixed gas fuel supplied to the engine 500 along the fuel supply line FL, a fuel pressure measuring unit 420 that measures the pressure of the mixed fuel supplied to the engine 500 along the fuel supply line FL, and a drain filter 430 that recovers recondensed VOCs in liquid state contained in the mixed fuel transported to the engine 500 along the fuel supply line FL.

[0088] In addition, the drain filter 430 may be provided with a level measuring unit 440 that measures the water level of the recondensed VOCs in liquid state collected by the drain filter 430, and an LVOC recovery valve 460 that discharges the recondensed VOCs collected by the drain filter 430.

[0089] The fuel temperature measuring unit 410, the fuel pressure measuring unit 420, and the drain filter 430 of this embodiment may be provided in the second section of the fuel supply line FL, that is, in the GVU room GR.

[0090] In addition, the recondensed VOC recycling means of this embodiment may further include an LVOC recovery tank 470 that recovers and stores the recondensed VOCs discharged from the drain filter 430, an LVOC recovery line RL that connects the drain filter 430 and the LVOC recovery tank 470 and provides a path for the recondensed VOCs discharged from the drain filter 430 to be transferred to the LVOC recovery tank 470, and an LVOC transfer pump 480 that pressurizes the recondensed VOCs collected in the LVOC recovery tank 470 and transfers them to the LVOC tank 200.

[0091] In this embodiment, the LVOC recovery tank 470 and the LVOC transfer pump 480 may be provided in an open space above the upper deck.

[0092] In this embodiment, the recondensed VOCs collected in the LVOC recovery tank 470 are transferred by the LVOC transfer pump 480 along the LVOC recovery line RL connecting the LVOC recovery tank 470 and the LVOC tank 200 to the LVOC tank 200, and are stored in the LVOC tank 200. That is, according to this embodiment, the recondensed VOCs collected from the drain filter 430 are resupplied as fuel for the engine 500 via the VOC supply unit.

[0093] According to this embodiment, since there is a risk of explosion or the like when liquid VOCs flow into the engine 500, the drain filter 430 of this embodiment may be installed in the second section of the fuel supply line FL, more specifically, between the gas valve unit 530, 610 and the double pipe 510.

[0094] In this embodiment, the mixed gas fuel transferred to the engine 500 flows through the fuel supply line FL and passes through the drain filter 430.

[0095] As shown in FIG. 1, a gas inlet pipe (not shown) through which mixed gas fuel flows is provided at the top of the drain filter 430 of this embodiment, and a funnel-shaped hopper (not shown) is provided at the bottom.

[0096] That is, the mixed gas fuel supplied to the engine 500 through the fuel supply line FL flows into the drain filter 430 through the gas inlet pipe of the drain filter 430 before being supplied to the engine 500, and the liquid state VOCs contained in the mixed gas fuel while passing through the drain filter 430 are collected at the bottom via a hopper.

[0097] In addition, the gas inlet pipe of the drain filter 430 may be configured to extend into the internal space of the drain filter 430 and have an end bent downward (in a "L" shape), with the bent portion facing the hopper downward.

[0098] The level measurement unit 440 of this embodiment detects the liquid level of the recondensed VOCs in a liquid state collected by the drain filter 430 and transmits the water level information to the control unit 800. In addition, the level measurement unit 440 may further have a function of detecting the liquid level of the recondensed VOCs in a liquid state collected by the drain filter 430 and generating an alarm to notify an operator when the measured water level reaches a preset water level.

[0099] When the level measurement unit 440 detects that the water level measurement value has reached a preset water level, the control unit 800 switches the operation mode of the engine 500 from the gas fuel mode to the oil fuel mode, and controls the system so that fuel oil is supplied to the engine 500. Alternatively, the operation mode of the engine 500 may be switched to a mode in which only gas is used as fuel, and gas fuel may be supplied to the engine 500 using the gas supply unit.

[0100] When the operating mode of the engine 500 is switched to the oil fuel mode, the VOC supply unit and the gas supply unit stop operating, and the fuel oil supply unit (not shown) is operated to supply fuel oil stored in the cargo tank 100 or a separate fuel oil storage tank (not shown) as fuel for the engine 500.

[0101] In addition, it is preferable that the level measuring unit 440 of this embodiment is a UV type level switch that detects the water level using ultraviolet light. Since the specific gravity of VOCs in a liquid state is very low at about 0.4, it is not possible to apply a ball float type level switch that detects the water level using buoyancy to the level measuring unit 440.

[0102] On the other hand, the fuel temperature measuring section 410 of this embodiment is a means for measuring the temperature of the mixed gas fuel supplied from the fuel mixing section 400 to the engine 500 along the fuel supply line FL.

[0103] The temperature measurement value measured by the fuel temperature measurement unit 410 is transmitted to the control unit 800. The control unit 800 can be configured to receive temperature information from the fuel temperature measurement unit 410 and stop the operation of the LVOC supply pump 210 when the measured temperature value becomes lower than a preset temperature.

[0104] That is, when the control unit 800 determines, using the temperature measurement value of the fuel temperature measurement unit 410, that recondensed VOCs have occurred or that the conditions for VOCs to recondense are met, it can execute the control logic of a safety device that cuts off the supply of VOC fuel from the LVOC tank 200 to the fuel mixing unit 400.

[0105] In this embodiment, the recondensation condition for VOCs may be 30° C. That is, the control unit 800 may stop the operation of the LVOC supply pump 210 if the temperature measured by the fuel temperature measuring unit 410 is 30° C. or lower.

[0106] Meanwhile, the gas valve unit installed in the GVU room GR to control the gas fuel supply includes double shutoff valve units 530, 610. The double shutoff valve units 530, 610 may include two shutoff valves 531, 611 that open and close the flow of fluid by opening and closing control and are installed in series with a gap between them, and pressure regulating valves 532, 612 that are installed on lines VL2, VL3 that branch off from the piping line between the two shutoff valves 531, 611 and connect to the vent mast, and that vent the fluid remaining in the piping line.

[0107] The double shutoff valve unit 530, 610 may include a gas shutoff valve unit 530 arranged on the fuel supply line FL, and the gas shutoff valve unit 530 may include two gas shutoff valves 531 and a gas pressure regulating valve 532 arranged in a gas vent line VL2 that branches off from the fuel supply line FL between the two gas shutoff valves 531 and connects to the vent mast.

[0108] For example, when a gas trip occurs in the engine 500, the two gas shutoff valves 531 are closed to cut off the flow of gas fuel. By cutting off the flow of gas fuel, the pressure increase between the two gas shutoff valves 531 is lowered by opening the gas pressure regulating valve 532 and discharging gas through the gas vent line VL2.

[0109] On the other hand, in order to restart the engine 500 after switching the fuel supply mode of the engine 500 and resolving a fuel supply problem such as a gas trip, it is necessary to remove any fluid remaining in the fuel supply line FL and perform a purge by supplying an inert gas.

[0110] Therefore, downstream of the gas shut-off valve unit 530 of the fuel supply line FL, an inert gas supply line NL is arranged which is provided on the ship and communicates with an inert gas supply unit 600 which generates and supplies an inert gas, such as nitrogen, to serve as a supply path for inert gas to the fuel supply line FL.

[0111] The dual shutoff valve units 530, 610 of this embodiment may include a purge shutoff valve unit 610 disposed on the inert gas supply line NL.

[0112] The purge shutoff valve unit 610 may include two purge shutoff valves 611 and a purge pressure regulating valve 612 arranged in a purge vent line VL3 that branches off from the inert gas supply line NL between the two purge shutoff valves 611 and connects to the vent mast.

[0113] For example, under normal circumstances, the two purge shutoff valves 611 are closed to provide a doubly shutoff of the inert gas supply line NL, and the purge pressure regulating valve 612 is opened to fundamentally prevent gas transported along the fuel supply line FL from flowing back toward the inert gas supply line NL. Under normal circumstances, the two purge shutoff valves 611 are closed, so even if gas flows back from the fuel supply line FL into the inert gas supply line NL, the doubly shutoff is provided by the purge shutoff valves 611, and the backflowing gas moves to the vent mast.

[0114] In this embodiment, the purge shutoff valve 611 is a valve capable of throttling, and the pressure of the inert gas passing through the purge shutoff valve 611 is gradually increased or decreased by adjusting the opening and closing speed.

[0115] According to this embodiment, the recondensed VOCs collected in the drain filter 430 can be recovered using the inert gas supply section 600, the inert gas supply line NL, and the gas valve units 530 and 610, which are essential components in conventional gas engine-based fuel supply systems.

[0116] According to this embodiment, in order to recover the recondensed VOCs collected by the drain filter 430, a filter shutoff valve 450 may be provided in the fuel supply line FL between the drain filter 430 and the double pipe 510, and when the recondensed VOCs are discharged from the drain filter 430, a filter shutoff valve 450 may be further provided to shut off the path so that the recondensed VOCs do not flow into the double pipe 510.

[0117] A method for recovering recondensed VOCs generated by supplying mixed gas fuel from the fuel mixing section 400 to the engine 500 will be described below.

[0118] First, the mixed gas fuel is transferred from the fuel mixing section 400 to the engine 500 via the fuel supply line FL, passing through the fuel temperature measuring section 410, the gas shutoff valve unit 530, the fuel pressure measuring section 420, the drain filter 430 and the double pipe 510 in that order. The recondensed VOCs in liquid state generated during the transfer of the mixed gas fuel are filtered by the drain filter 430, which is downstream of the gas shutoff valve unit 530 and upstream of the double pipe 510.

[0119] The level measurement unit 440 measures the water level of the recondensed VOCs collected by the drain filter 430 and transmits the water level information to the control unit 800. When the control unit 800 detects that the water level measured by the level measurement unit 440 exceeds a preset level, it stops the gas fuel mode of the engine 500 and switches it to the oil fuel mode.

[0120] When the gas fuel mode of the engine 500 is stopped, the vent valve 520 is operated to open automatically or by a command from the control unit 800. That is, when the gas fuel mode of the engine 500 is stopped, the vent valve 520 is opened and the mixed gas fuel remaining in the double pipe 510 and the engine 500 is vented to the vent mast through the first vent line VL1.

[0121] The filter shutoff valve 450 is open when the engine 500 is operating in gas fuel mode, but is operated to close automatically or by the control unit 800 when all of the mixed gas fuel remaining in the double pipe 510 and the engine 500 has been vented.

[0122] In addition, the control unit 800 controls the gas shutoff valve 531 to be closed and the purge shutoff valve 611 to be opened when the filter shutoff valve 450 is closed, so that the inert gas flows from the inert gas supply unit 600 into the drain filter 430 downstream of the gas shutoff valve 530.

[0123] VOCs in liquid form, or LVOCs, have a specific gravity of approximately 0.4 and can be transported using the pressure of an inert gas (eg, nitrogen).

[0124] At this time, the control unit 800 checks the pressure measurement value measured by the fuel pressure measurement unit 420 provided in the fuel supply line FL between the gas shutoff valve unit 530 and the drain filter 430, and gradually opens the purge shutoff valve 611 so that the pressure measurement value gradually increases.

[0125] The pressure of the inert gas supplied from the inert gas supply unit 600 is approximately 6 bar. If the purge shutoff valve 611 is suddenly opened, the relatively high pressure of the inert gas at 6 bar will suddenly flow into the drain filter 430, causing the recondensed VOCs in liquid state collected in the drain filter 430 to fly out or be accompanied by droplets.

[0126] Therefore, in this embodiment, it is preferable that purge shutoff valve 611 is gradually opened while adjusting the opening speed of purge shutoff valve 611 according to the pressure measurement value of fuel pressure measurement unit 420 so that the pressure of the inert gas flowing into drain filter 430 does not increase suddenly, and the pressure measurement value per unit time does not exceed a preset pressure change rate.

[0127] In addition, when the pressure measurement value by the fuel pressure measurement unit 420 reaches a preset reference value, the control unit 800 of this embodiment opens the LVOC recovery valve 460 and transfers the liquid-state recondensed VOCs collected in the drain filter 430 to the LVOC recovery tank 470 via the LVOC recovery line RL.

[0128] The LVOC recovery tank 470 of this embodiment must be installed above the upper deck of the ship and in an area classified as a safe area, which minimizes the risk of explosion affecting other equipment or areas.

[0129] When the transfer of the recondensed VOCs from the drain filter 430 to the LVOC recovery tank 470 is completed, the control unit 800 opens the filter shutoff valve 450 and supplies nitrogen from the inert gas supply unit 600 to the engine 500 to perform a purging operation.

[0130] When the purging operation is completed, the control unit 800 switches the engine 500 back to the gas fuel mode, closes the purge shutoff valve 611, opens the gas shutoff valve 531, and controls each device so that mixed gas fuel is supplied from the fuel mixing unit 400 to the engine 500.

[0131] In this embodiment, the recondensed VOCs collected in the LVOC recovery tank 470 can be transferred to the LVOC tank 200 using the LVOC transfer pump 480, so that the recondensed VOCs separated by the drain filter 430 can be recovered again in the VOC supply section and used as gas fuel for the engine 500.

[0132] Next, a VOC fuel supply system and method for a ship according to a second embodiment of the present invention will be described with reference to FIGS.

[0133] The second embodiment of the present invention described below is a modified version of the first embodiment described above, and differs in the method of recovering VOCs remaining in the piping when the gas fuel mode in which VOCs are supplied as fuel to the engine 500 is stopped due to a trip, mode switching, or other reason.

[0134] More specifically, the VOC fuel supply system for a ship according to a second embodiment of the present invention, which will be described later, differs from the first embodiment of the present invention in that it further includes an LVOC purge line NL1, an LVOC purge valve 540, a fourth vent line VL4, a VOC vent valve 620, a purge temperature measurement unit 550, a cooling line CL, and a cooling valve 730 to purge the fuel supply line FL and the double pipe 510 when the gas fuel mode is stopped.

[0135] Meanwhile, in the VOC fuel supply system for a ship according to the second embodiment of the present invention, the filter shutoff valve 450, vent line VL1, vent valve 520, and the line connecting the inert gas supply line NL to the fuel supply line FL between the gas shutoff valve 531 and the drain filter 430 downstream of the purge shutoff valve 611 of the first embodiment are not included and can be omitted.

[0136] Alternatively, even if the above configuration is included, when purging the piping, the LVOC purge line NL1, LVOC purge valve 540, fourth vent line VL4, VOC vent valve 620, purge temperature measurement unit 550, cooling line CL, and cooling valve 730 which are not included in the VOC fuel supply system for a ship of the first embodiment but are included only in this embodiment can be used.

[0137] In explaining this embodiment, an example will be given in which the vent line VL1, vent valve 520, and the line connecting the inert gas supply line NL to the fuel supply line FL between the gas shutoff valve 531 and the drain filter 430 downstream of the purge shutoff valve 611 in the first embodiment are not included.

[0138] The following description will focus on the differences from the first embodiment described above, and detailed descriptions of other components and their operations will be omitted. Even if omitted, the description of the first embodiment described above can be applied to parts that are given the same drawing symbols and their operations.

[0139] Meanwhile, the engine 500 according to an embodiment of the present invention can also be operated in an oil fuel mode using diesel as fuel. Therefore, the ship according to an embodiment of the present invention needs to be equipped with an SCR (Selective Catalytic Reduction) system that removes nitrogen oxides (NOx) in the exhaust gas discharged from the engine 500. The SCR system is a device for removing nitrogen oxides in the exhaust gas by chemically reacting with a reducing agent in a catalyst layer.

[0140] The SCR system may include a reductant tank 920 for storing a reductant for reacting with the nitrogen oxides, a chiller unit 910 for cooling the reductant, and a reactor (not shown) in which a catalyst layer is formed and the reaction between the nitrogen oxides in the exhaust gas and the reductant occurs.

[0141] The reducing agent is urea water (urea) or ammonia, and in this embodiment, urea water will be described as an example. The temperature of the reducing agent tank 920 that stores the urea water needs to be constantly maintained at about 30° C. or less in order to store the reducing agent for a long period of time.

[0142] The low-temperature heat medium cooled by the chiller unit 910 is supplied to the reducing agent tank 920 via piping (not given a reference number in the drawing) connecting the chiller unit 910 and the reducing agent tank 920, and the high-temperature heat medium that has become hot while cooling the reducing agent tank 920 is recovered back into the chiller unit 910, thereby enabling the reducing agent tank 920 to be maintained at the required temperature.

[0143] The VOC fuel supply system for a ship according to this embodiment may further include a cooling line CL that supplies a low-temperature heat medium cooled in the chiller unit 910 to the double pipe 510 to cool the double pipe 510, and a cooling valve 930 provided in the cooling line CL.

[0144] In this embodiment, by supplying a low-temperature heat transfer medium to the double pipe 510 via the cooling line CL, the VOCs remaining in the double pipe 510 can be condensed, and the LVOCs remaining in a liquid state can be cooled and recovered.

[0145] When the double pipe 510 is cooled using a low-temperature heat medium provided with a cooling line CL, the VOCs remaining in the double pipe 510 are condensed and the remaining LVOCs are cooled, so in this embodiment, the condensed LVOCs or cooled LVOCs can be recovered in the drain filter 430 via the inner pipe of the double pipe 510 and the fuel supply line FL.

[0146] In the first embodiment described above, a filter shutoff valve 450 is provided to block the path so that recondensed VOCs do not flow into the double pipe 510. In this embodiment, however, the filter shutoff valve 450 can be omitted, or the filter shutoff valve 450 can be kept open during purging.

[0147] The cooling line CL in this embodiment may form a circulation line that runs from the chiller unit 910 to the downstream end of the double pipe 510 based on the fuel flow direction, passes through the drain filter 430, and connects to the chiller unit 910 again.

[0148] That is, the low-temperature heat transfer medium flows along the cooling line CL in a direction opposite to the normal flow direction of the gas fuel, and is supplied from the engine 500 to the drain filter 430. The heat transfer medium collected in the drain filter 430 is recirculated to the chiller unit 910 along the cooling line CL.

[0149] In this embodiment, a purge temperature measuring unit 550 that is provided in the fuel supply line FL between the drain filter 430 and the double pipe 510 and measures the temperature of the fluid recovered from the double pipe 510 to the drain filter 430 may further be provided.

[0150] The control unit 800 controls the cooling valve 930 in response to the temperature measurement value of the purge temperature measurement unit 550 to control the cooling temperature of the double pipe 510 .

[0151] In this embodiment, the system may further include an LVOC purge line NL1 extending from the inert gas supply line NL through a purge shutoff valve 611 to an end of the double pipe 510, and an LVOC purge valve 540 provided in the LVOC purge line NL1.

[0152] Furthermore, this embodiment may further include a fourth vent line VL4 that branches off from the fuel supply line FL downstream of the gas shutoff valve 531 and connects to the vent mast, and a VOC vent valve 620 provided in the fourth vent line VL4.

[0153] The control unit 800 controls the LVOC purge valve 540 to supply nitrogen from the nitrogen supply unit 600 to the end of the double pipe 510 via the LVOC purge line NL1, thereby transferring the VOCs remaining in the double pipe 510 in liquid state to the drain filter 430.

[0154] In addition, the control unit 800 can control the LVOC purge valve 540 to supply nitrogen to the end of the double pipe 510 via the LVOC purge line NL1, while also controlling the VOC recovery valve 460 to transfer the LVOC recovered in the drain filter 430 to the LVOC recovery tank 470 via the LVOC recovery line RL.

[0155] When the engine 500 according to this embodiment operates in a gas fuel mode, the method of supplying mixed gas fuel or VOCs to the engine 500 is similar to that of the first embodiment.

[0156] Mixed gas fuel (or VOC) flows from the fuel mixing section 400 along the fuel supply line FL, passes through the fuel temperature measuring section 410, the gas shutoff valve 531, the fuel pressure measuring section 420, the drain filter 430 and the purge temperature measuring section 550, and is supplied to the combustion chamber in the engine 500 through the inner tube of the double tube 510.

[0157] The liquid LVOCs produced by condensation of the gaseous VOCs during the transfer of the mixed gas fuel are filtered by the drain filter 430 disposed downstream of the gas shutoff valve 531 and upstream of the double pipe 510 .

[0158] The gas fuel mode can be stopped when a trip occurs in the engine 500, the fuel supply device, or the like, and it is necessary to switch the operation mode of the engine 500 to the oil fuel mode depending on the operational status of the ship, etc.

[0159] For example, the control unit 800 receives the water level measurement value of the drain filter 430 measured by the level measurement unit 440, and when the water level measurement value exceeds a preset value, stops the gas fuel mode of the engine 500 and switches it to the oil fuel mode.

[0160] Gas fuel that is recovered without being injected into the combustion chamber of the engine 500, or gas fuel remaining in the piping when a problem occurs in the engine 500 such as a gas trip or when attempting to switch the operating mode of the engine 500 from gas fuel mode to oil fuel mode, particularly VOCs, can be recovered in liquid form by the method of this embodiment.

[0161] In this embodiment, the method of recovering LVOC while purging the fuel supply line FL and the double pipe 510 when the gas fuel mode is stopped is as follows.

[0162] Unlike the first embodiment described above, which recovers recondensed VOCs generated by supplying mixed gas fuel from the fuel mixing section 400 to the engine 500, the present embodiment differs in that the VOCs remaining in the piping in a gaseous state are also condensed and recovered in a liquid state.

[0163] In this embodiment, when the gas fuel mode is stopped, first, the gas shutoff valve 531, which is in the open position in the gas fuel mode, is controlled to be in the closed position. At this time, the operation of the LVOC supply pump 210 is also stopped.

[0164] After the gas shutoff valve 531 is closed, the pressure in the fuel supply line FL and the double pipe 510 downstream of the gas shutoff valve 531 is maintained as it is.

[0165] The control unit 800 opens the cooling valve 930 when the gas shutoff valve 531 is closed, and controls so that at least a portion of the high-temperature heat medium that has cooled the reducing agent tank 920 and become hot flows into the cooling line CL.

[0166] The temperature of the high-temperature heat medium that has been heated by cooling the reducing agent tank 920, i.e., the heat medium flowing into the cooling line CL, is about 10-15° C. or lower, preferably about 12° C. or lower. Therefore, the temperature of the high-temperature heat medium is low enough to condense the gaseous VOCs remaining in the double pipe 510 while cooling the pipe.

[0167] When the cooling valve 930 is opened and the heat medium flows into the cooling line CL, the heat medium can rapidly cool the double pipe 510 as it flows along the cooling line CL surrounding the double pipe 510 from the end of the double pipe 510 in the engine 500 to the upstream fuel supply line FL.

[0168] The heat medium, which has become hot after cooling the double pipe 510 along the cooling line CL, is recirculated to the chiller unit 910 again.

[0169] The cooling line CL is provided passing through the drain filter 430 so that the heat medium recirculated to the chiller unit 910 can also condense the gaseous VOCs remaining in the drain filter 430 .

[0170] Meanwhile, the temperature measured by purge temperature measurement unit 550, which measures the temperature of fuel supply line FL upstream of double pipe 510, is transmitted to control unit 800. Control unit 800 cools double pipe 510 by flowing a heat medium until the temperature measured by purge temperature measurement unit 550, i.e., the temperature of fuel supply line FL upstream of double pipe 510, becomes less than a preset value.

[0171] The control unit 800 of this embodiment can cool the temperature measured by the purge temperature measurement unit 550 to a temperature at which VOCs condense, which is about 30° C. in this embodiment. That is, when the temperature measured by the purge temperature measurement unit 550 falls below 30° C., the control unit 800 closes the cooling valve 930 to interrupt cooling of the double pipe 510.

[0172] Furthermore, when the cooling valve 930 is closed, the control unit 800 controls the LVOC purge valve 540 to be opened, and transfers the inert gas from the inert gas supply unit 600 through the LVOC purge line NL1 to the double pipe 510. At this time, the purge shutoff valve 611 is controlled to be opened.

[0173] The inert gas transferred from the inert gas supply unit 600 via the LVOC purge line NL1 flows through the double pipe 510 and the fuel supply line FL to the drain filter 430. By supplying the inert gas to the drain filter 430 via the double pipe 510 and the fuel supply line FL, the LVOC in a liquid state remaining in the double pipe 510 and the fuel supply line FL is also transferred to the drain filter 430. At this time, if a filter shutoff valve 450 is provided, the filter shutoff valve 450 is controlled to be displaced open.

[0174] On the other hand, when the control unit 800 supplies the inert gas to the double pipe 510 through the LVOC purge line NL1, the control unit 800 checks the pressure measurement value of the fuel pressure measurement unit 420 and controls the opening of the purge shutoff valve 611 so that the pressure measurement value of the fuel pressure measurement unit 420 gradually increases.

[0175] The pressure of the inert gas supplied from the inert gas supply unit 600 is approximately 6 bar. When the purge shutoff valve 611 is suddenly opened, the relatively high pressure inert gas of 6 bar suddenly flows into the drain filter 430, causing the LVOC collected in the drain filter 430 to fly out and be accompanied by droplets.

[0176] In addition, when the inert gas starts to flow into the drain filter 430, the control unit 800 opens the VOC vent valve 620 and controls the gas in the drain filter 430, i.e., the inert gas, to be supplied to the vent mast through the fourth vent line VL4.

[0177] In addition, when the pressure measurement value of the fuel pressure measurement unit 420 increases to a set value, the control unit 800 controls the LVOC recovery valve 460 to open so that the LVOC collected in the drain filter 430 is recovered in the LVOC recovery tank 470 via the LVOC recovery line RL.

[0178] The LVOC recovery tank 470 is located in an open safety area above the upper deck to minimize the impact of an explosion on other areas.

[0179] The recondensed VOCs recovered in the LVOC recovery tank 470 flow into the LVOC recovery line RL connecting the LVOC recovery tank 470 and the LVOC tank 200 by the LVOC transfer pump 480, and are transported to the LVOC tank 200 and stored therein.

[0180] That is, in this embodiment, the LVOC from the drain filter 430 is resupplied with the fuel of the engine 500 via the VOC supply unit.

[0181] Once the above steps are completed, the purging of the dual pipe 510 and fuel supply line FL is considered complete and the gas or oil fuel mode can be resumed.

[0182] As described above, an embodiment of the present invention can prevent condensed liquid gas from entering the engine 500 using a mixed fuel of VOC and LNG.

[0183] In addition, by utilizing the basic equipment already installed on the ship, namely the chiller unit 910 and the inert gas supply unit 600 connected to the GVU room GR, the VOCs can be condensed and recovered in liquid form, and purging of the piping and recovery of the LVOCs can be easily controlled using only temperature and pressure measurements.

[0184] The present invention is not limited to the above-described embodiments, and it is obvious to a person having ordinary skill in the art to which the present invention pertains that the present invention can be modified or changed in various forms without departing from the technical gist of the present invention. [Explanation of symbols]

[0185] 100: Cargo tank 200:LVOC tank 210: LVOC supply pump 220: LVOC vaporizer 230:VOC compressor 240: Cooling section 250: Condenser 300: Fuel tank 310: Fuel supply pump 320: LNG vaporizer 330:BOG heater 400: Fuel mixing section 410:Fuel temperature measurement part 420: Fuel pressure measuring unit 430: Drain filter 440: Level measurement section 450: Filter shutoff valve 460: LVOC recovery valve 470: LVOC recovery tank 480: LVOC transfer pump 500: Engine 510:Double tube 520: Vent valve 530: Gas shutoff valve unit 531: Gas shutoff valve 532: Gas pressure regulating valve 540: LVOC purge valve 550: Purge temperature measurement unit 600: Inert gas supply unit 610: Purge shutoff valve unit 611: Purge shutoff valve 612: Purge pressure adjustment valve 620: VOC vent valve 700: Ventilation fan 710: Exhaust duct 720: Damper 800: Control unit 910: Chiller unit 920: Reductant tank 930: Cooling valve FL: Fuel supply line RL: LVOC recovery line NL: Inert gas supply line VL1, VL2, VL3, VL4: Vent lines NL1: LVOC purge line CL: Cooling line ER: Engine room GR:GVU Room

Claims

1. An engine using gas as fuel and operating in a gas fuel mode; a VOC supply unit that adjusts volatile organic compounds (VOCs) to pressure and temperature conditions required by the engine and supplies the VOCs to the engine as fuel; a gas supply unit that adjusts a gas fuel having a calorific value higher than the VOC to pressure and temperature conditions required by the engine and supplies the gas fuel to the engine; a fuel mixing unit that mixes the gas fuel supplied from the gas supply unit and the VOC supplied from the VOC supply unit to supply a mixed gas fuel to the engine; a fuel supply line that connects the fuel mixing unit and the engine and is a path through which the mixed gas fuel is transferred from the fuel mixing unit to the engine; a drain filter provided in the fuel supply line for separating recondensed VOCs in a liquid state condensed in the process of supplying the mixed gas fuel from the fuel mixing section to the engine from the mixed gas fuel; a recondensed VOC recycling means for removing the recondensed VOC in a liquid state separated by the drain filter from the fuel supply line, recovering the removed recondensed VOC, and recycling it as fuel for the engine; VOC fuel supply system.

2. The drain filter is A funnel-shaped hopper at the bottom; a gas inlet pipe provided at an upper portion, one end of which extends from the fuel supply line and the other end of which is bent toward the hopper, for introducing the VOC fuel into the drain filter; The liquid recondensed VOC contained in the VOC fuel is collected under the hopper, and only the gaseous VOC fuel from which the liquid recondensed VOC is separated is discharged.

2. The VOC fuel delivery system of claim 1.

3. The recondensation VOC recycling means comprises: a fuel temperature measuring unit provided in a fuel supply line upstream of the drain filter and configured to measure a temperature of the gas fuel supplied to the engine; A control unit that stops the operation of the VOC supply unit when the temperature measurement value of the fuel temperature measurement unit becomes lower than a preset temperature.

2. The VOC fuel delivery system of claim 1.

4. The recondensation VOC recycling means comprises: a level measuring unit for measuring a water level of the drain filter; a filter shutoff valve for shutting off the flow of fluid from said drain filter to the engine; a vent valve between the filter shutoff valve and the engine, and for venting gas fuel from the engine; a control unit that stops the operation of the VOC supply unit, closes the filter shutoff valve, and opens the vent valve when the water level measurement value by the level measurement unit reaches a preset water level.

2. The VOC fuel delivery system of claim 1.

5. The recondensation VOC recycling means comprises: an LVOC recovery valve for discharging recondensed VOCs in liquid form collected by said drain filter; an LVOC recovery tank for storing recondensed VOCs discharged from said drain filter; an LVOC transfer pump that supplies the recondensed VOC stored in the LVOC recovery tank to the VOC supply unit; 2. The VOC fuel delivery system of claim 1.

6. The recondensation VOC recycling means comprises: An inert gas supply unit that supplies an inert gas to the drain filter and discharges the recondensed VOCs collected by the drain filter from the drain filter.

2. The VOC fuel delivery system of claim 1.

7. The recondensation VOC recycling means comprises: a double shutoff valve unit for shutting off between the VOC supply unit and the drain filter when supplying an inert gas to the drain filter; a filter shutoff valve for shutting off between the drain filter and the engine when supplying an inert gas to the drain filter; a fuel pressure measuring unit that measures the pressure of the fluid supplied from the fuel supply line to the drain filter; an LVOC recovery valve for discharging recondensed VOCs in liquid form collected by said drain filter; a control unit that opens the LVOC recovery valve when the pressure measurement value of the fuel pressure measurement unit reaches a preset pressure.

7. The VOC fuel delivery system of claim 6.

8. The dual shutoff valve unit comprises: a valve for adjusting the pressure of the fluid passing through the dual shutoff valve unit; The control unit controls an opening degree of the double shutoff valve unit so that the pressure measurement value of the fuel pressure measurement unit does not exceed a preset pressure change rate, thereby adjusting the pressure of the inert gas supplied to the drain filter.

8. The VOC fuel delivery system of claim 7.

9. a cooling line through which a heat transfer medium circulates for cooling the fuel supply line and condensing the gaseous VOCs remaining in the fuel supply line; a cooling valve provided in the cooling line; A control unit that controls the cooling valve to open when the gas fuel mode is stopped.

2. The VOC fuel delivery system of claim 1.

10. a reducing agent tank for storing a reducing agent for denitrifying exhaust gas discharged from the engine; a chiller unit that circulates a heat medium to maintain the temperature of the reducing agent tank; The cooling line is characterized in that it branches off from a line through which the heat medium, which has been heated by cooling the reducing agent tank, is recirculated to the chiller unit and is connected to an end of the fuel supply line.

10. The VOC fuel delivery system of claim 9.

11. an inert gas supply unit that supplies an inert gas to the fuel supply line to exhaust LVOCs in a liquid state remaining in the fuel supply line; an LVOC purge line connecting the inert gas supply and the fuel supply line; an LVOC purge valve provided in the LVOC purge line; a purge temperature measuring unit for measuring a temperature of the fuel supply line; The control unit opens the LVOC purge valve when the temperature measurement value of the purge temperature measurement unit reaches a preset value, so that an inert gas is supplied to the fuel supply line, and the LVOC is discharged from the fuel supply line by the inert gas.

10. The VOC fuel delivery system of claim 9.

12. The drain filter temporarily stores the inert gas and LVOCs discharged from the fuel supply line, a fourth vent line for transporting gas exhausted from the drain filter; a VOC vent valve provided in the fourth vent line; an LVOC recovery line for transporting liquid discharged from said drain filter; an LVOC recovery valve provided in the LVOC recovery line; a fuel pressure measuring unit for measuring the pressure of the fuel supply line; The control unit opens the VOC vent valve and the LVOC recovery valve when the pressure measurement value of the fuel pressure measurement unit reaches a preset value.

12. The VOC fuel delivery system of claim 11.

13. A ship that uses VOCs as fuel, comprising the VOC fuel supply system according to any one of claims 1 to 12.

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