KR20220049055A - Gas management system in ship - Google Patents

Abstract

A gas management system of a ship is disclosed. A gas management system of a ship according to an embodiment of the present invention comprises: at least one storage tank accommodating a liquefied gas and a boil-off gas; a boil-off gas supply line having a first compression unit for compressing the boil-off gas of the storage tank, and supplying the boil-off gas, compressed by the first compression unit, to an engine; a re-liquefying line provided with a heat exchanger receiving a portion of the boil-off gas compressed by the first compression unit to exchange heat with a relatively low temperature boil-off gas transferred among a boil-off gas supply line and to cool the same; and a buffer tank disposed between the first compression unit on the boil-off gas supply line and the heat exchanger so as to buffer any one among a temperature change, a flow rate change and a pressure change of the boil-off gas introduced into the first compression unit. The present invention can efficiently operate a facility with a simple structure.

Description

Ship's gas management system {GAS MANAGEMENT SYSTEM IN SHIP}

The present invention relates to a gas management system for a ship, and more particularly, to a gas management system for a ship that can promote stable and efficient operation of various facilities by utilizing and processing liquefied natural gas and boil-off gas generated therefrom. will be.

As the International Maritime Organization (IMO)'s regulations on the emission of greenhouse gases and various air pollutants are strengthened, the shipbuilding and shipping industry replaces the existing fuels such as heavy oil and diesel oil, and uses natural gas, a clean energy source, as fuel gas for ships. is being used more and more.

In general, natural gas is cooled to about -163 ℃ for ease of storage and transportation, phase-changed into liquefied natural gas, and then charged into the ship's fuel tank or storage tank. It is used as a fuel for ships or transported to remote customers.

Such liquefied natural gas is stored and transported by being accommodated in a storage tank installed after being insulated on the hull. However, since it is practically impossible to implement complete insulation of the liquefied natural gas, external heat is continuously transferred to the inside of the storage tank, and the boil-off gas generated by the natural vaporization of the liquefied natural gas is accumulated inside the storage tank. . BOG raises the internal pressure of the storage tank and may cause deformation and damage to the storage tank, so it is necessary to process and remove BOG.

For this reason, conventionally, a method of flowing the boil-off gas through a vent mast provided on the upper side of the storage tank or burning the boil-off gas using a gas combustion unit (GCU) has been used. However, since this is undesirable in terms of energy efficiency, a method of supplying BOG together with liquefied natural gas or as fuel gas to a ship's engine, respectively, or re-liquefying BOG using a reliquefaction device consisting of a refrigeration cycle, etc. is being used

Republic of Korea Patent Publication No. 10-2010-0035223 (published on April 05, 2010)

This embodiment is intended to provide a gas management system of a ship that can reduce the load applied to the compressor for pressurizing the boil-off gas and promote stable operation.

This embodiment is intended to provide a gas management system of a ship capable of promoting stable and efficient facility operation with a simple structure.

This embodiment intends to provide a gas management system for a ship that can efficiently utilize and manage liquefied natural gas and boil-off gas generated therefrom.

The present embodiment is intended to provide a gas management system of a ship capable of promoting structural stability of various facilities such as a compressor or a pipeline.

This embodiment is intended to provide a gas management system for a ship capable of stably performing a fuel gas supply process and a reliquefaction process of boil-off gas to an engine.

According to an aspect of the present invention, at least one storage tank for accommodating liquefied gas and boil-off gas; a boil-off gas supply line provided with a first compression unit for pressurizing the boil-off gas of the storage tank and supplying the boil-off gas pressurized by the first compression unit to the engine; a reliquefaction line provided with a heat exchanger for receiving a portion of the BOG pressurized by the first compression unit and cooling the BOG by heat exchange with a relatively low temperature BOG transported along the BOG supply line; and a buffer tank provided between the heat exchanger and the first compression unit on the boil-off gas supply line to buffer at least any one of temperature change, flow rate change, and pressure change of the boil-off gas flowing into the first compression unit can be

It may be provided by further comprising a vaporization gas supply line for supplying the buffer tank by vaporizing the liquefied gas in the storage tank.

The vaporized gas supply line may include a delivery pump for pressurizing and delivering the liquefied gas of the storage tank, and a vaporizer for vaporizing the liquefied gas transferred by the delivery pump.

It may be provided by further comprising a liquefied gas spray line for controlling the internal temperature of the buffer tank.

It may be provided by further comprising a droplet removal line for recovering the liquid component generated inside the buffer tank to the storage tank.

The liquefied gas spray line may be provided with a spray nozzle having an inlet end branched from the rear end of a delivery pump on the vaporized gas supply line, and an outlet end disposed inside the buffer tank.

The BOG supply line may include a BOG bypass line for supplying BOG from the storage tank to the buffer tank, bypassing the heat exchanger and supplying BOG.

The boil-off gas supply line includes a first flow rate control valve for controlling a flow rate of boil-off gas supplied to the buffer tank via the heat exchanger, and a flow rate of boil-off gas supplied to the buffer tank through the boil-off gas bypass line. It may be provided by further comprising a second flow control valve to.

The first compression unit may include at least one first compressor and at least one first cooler for cooling the boil-off gas compressed and heated by the first compressor.

The reliquefaction line includes a second compression unit that additionally pressurizes the incoming boil-off gas and transfers it to the heat exchanger, a first gas-liquid separator that receives the boil-off gas cooled by the heat exchanger and separates it into a gas component and a liquid component; It may include a gas component circulation line for transferring the gas component of the first gas-liquid separator, and an expander provided in the gas component circulation line to depressurize the gas component of the first gas-liquid separator.

The reliquefaction line accommodates the boil-off gas in a gas-liquid mixed state decompressed by the expander and separates it into a gas component and a liquid component, and supplies the liquid component of the first gas-liquid separator to the second gas-liquid separator. a liquid component circulation line to It may be provided by further comprising a liquid component recovery line for supplying to the storage tank.

The reliquefaction line may further include a pressure reducing valve for reducing the pressure of the liquid component transferred along the liquid component circulation line.

The second compression unit may include at least one second compressor, and the second compressor and the expander may be provided as companders in which the second compressor pressurizes boil-off gas by the expansion force of the expander.

The second compression unit may further include at least one second cooler for cooling the boil-off gas compressed and heated by the second compressor.

The gas management system of the ship according to the present embodiment has the effect of reducing the load applied to the compressor for pressurizing the boil-off gas and promoting stable operation.

The gas management system of a ship according to this embodiment has a simple structure and has the effect of promoting stable and efficient facility operation.

The gas management system of the ship according to this embodiment has the effect of efficiently utilizing and managing liquefied natural gas and boil-off gas generated therefrom.

The gas management system of a ship according to this embodiment has an effect of promoting structural stability of various facilities such as a compressor or a pipeline.

The ship's gas management system according to this embodiment has the effect of stably performing the fuel gas supply process and the boil-off gas reliquefaction process to the engine.

1 is a conceptual diagram illustrating a gas management system of a ship according to the present embodiment.

Hereinafter, this embodiment will be described in detail with reference to the accompanying drawings. The following examples are presented to sufficiently convey the spirit of the present invention to those of ordinary skill in the art to which the present invention pertains. The present invention is not limited to the embodiments presented herein, and may be embodied in other forms. The drawings may omit the illustration of parts not related to the description in order to clarify the present invention, and slightly exaggerate the size of the components to help understanding.

1 is a conceptual diagram illustrating a gas management system 100 of a ship according to the present embodiment.

Referring to FIG. 1 , in the ship's gas management system 100 according to an embodiment of the present invention, a storage tank 110 , a first compression unit 121 for pressurizing the boil-off gas of the storage tank 110 is provided, and the second 1 The boil-off gas supply line 120 for supplying the boil-off gas pressurized through the compression unit 121 to the engine 10, the re-liquefaction line 130 for receiving and re-liquefying a portion of the pressurized boil-off gas, the first compression Buffer tank 180 for buffering at least any one of temperature change, flow rate change, and pressure change of the boil-off gas flowing into the unit 121, various valves 136a, 151, 161, 171, 181, 182, 183 may be provided including a control unit (not shown) for controlling the opening and closing operation.

The storage tank 110 is provided to accommodate or store liquefied natural gas and boil-off gas generated therefrom. The storage tank 110 may be provided as a membrane-type cargo hold insulated to minimize vaporization of liquefied natural gas due to external heat intrusion. The storage tank 110 receives or stores liquefied natural gas from a natural gas production area, etc., and stably stores the liquefied natural gas and boil-off gas until it reaches its destination and is unloaded, but as will be described later, a propulsion engine of a ship or a ship It may be provided to be used as a fuel gas, such as an engine for power generation.

The storage tank 110 is generally installed with thermal insulation, but it is practically difficult to completely block the intrusion of external heat. do. Since such BOG raises the internal pressure of the storage tank 110 and poses a risk of deformation and explosion of the storage tank 110 , there is a need to remove or process BOG from the storage tank 110 . Accordingly, the boil-off gas generated inside the storage tank 110 is used as fuel gas of the engine by the boil-off gas supply line 120 as in this embodiment or is reliquefied by the re-liquefaction line 130 to the storage tank 110 ) can be resupplied. In addition, although not shown in the drawings, the boil-off gas may be treated or consumed by supplying it to a vent mast (not shown) provided on the upper portion of the storage tank 110 .

The engine 10 may receive fuel gas such as liquefied natural gas and boil-off gas accommodated in the storage tank 110 to generate propulsion force of the ship or to generate power for power generation such as internal facilities of the ship. The engine 10 includes the natural BOG naturally generated inside the storage tank 110 through a boil-off gas supply line 120 to be described later, and the inside of the storage tank 110 by a vaporized gas supply line 190 to be described later. It is possible to generate output by receiving vaporized BOG generated by forcibly vaporizing the liquefied natural gas of

1 illustrates one engine 10 receiving pressurized boil-off gas as fuel gas from the boil-off gas supply line 120 to be described later, but is not limited thereto, and the engine 10 is a fuel gas of relatively high pressure. It may include at least one of a high-pressure engine that receives the supply and generates output, a low-pressure engine that receives a relatively low-pressure fuel gas to generate output, and a gas combustion unit (GCU) that receives and consumes excess fuel gas. . For example, the engine 10 may include a ME-GI engine or X-DF engine capable of generating output with fuel gas of relatively high pressure, a DFDE engine capable of generating output with fuel gas of relatively low pressure, etc. can

The boil-off gas supply line 120 may be provided to supply the boil-off gas present in the storage tank 110 to the engine 10 and the reliquefaction line 130 by pressurizing the boil-off gas present in the storage tank 110 by a first compression unit 121 to be described later. . The boil-off gas supply line 120 may have an inlet end connected to the inside of the storage tank 110 , and an outlet end connected to the engine 10 . When a plurality of engines 10 are provided and fuel gas of different pressure levels is supplied, a pressure reducing valve (not shown) for adjusting the pressure of the pressurized boil-off gas according to the required pressure level of each engine 10 may be provided. can

The BOG supply line 120 may be provided with a first compression unit 121 that pressurizes BOG discharged from the storage tank 110 according to the conditions required by the engine 10 . The first compression unit 121 may include a first compressor 121a for compressing the boil-off gas introduced through the boil-off gas supply line 120 and a first cooler 121b for cooling the boil-off gas heated while being compressed. can When the engine 10 includes a plurality of engines having different pressure conditions, a branch line (not shown) is branched from the middle portion of the first compression unit 121 to release some pressurized BOG toward the engine 10 . can supply In addition, a heat exchanger 132 and a buffer tank 190 of the reliquefaction line 130 to be described later may be provided at the front end of the first compression unit 121 on the boil-off gas supply line 120 , which will be described later in detail. to do it

A plurality of first compressors 121a of the first compression unit 121 may be provided and disposed in parallel with each other, and the first coolers 121b may be provided at the rear end of each first compressor 121a. As the plurality of first compressors 121a are arranged in parallel with each other, even in a state in which one of the first compressors 121a is inoperable such as failure or maintenance, the other first compressors 121a arranged in parallel are operated. BOG generated in the storage tank 110 can be stably treated. In addition, even when the flow rate of BOG generated in the storage tank 110 is large, by simultaneously operating the plurality of first compressors 121a, it may be possible to effectively respond and process the amount of BOG generated from time to time changing. On the other hand, an on/off valve for allowing and blocking the flow of boil-off gas is provided at the front end of each of the first compressors 121a, respectively, and the control unit controls the operation of the on/off valve according to various operating conditions to control the operation of the on/off valve according to various operating conditions to control the operation of the plurality of first compressors 121a. ), at least one of which can be selectively operated. In addition, in FIG. 1 , the first compression unit 121 is provided with three first compressors 121a and a first cooler 121b and is illustrated as being disposed in parallel, but this is an example of the required pressure condition and temperature of the engine. Accordingly, the first compressor 121a and the first cooler 121b may be formed in various numbers.

On the other hand, the heat exchanger 132 of the reliquefaction line 130 to be described later exchanges the low-temperature BOG introduced into the BOG supply line 120 and the high-temperature BOG introduced into the reliquefaction line 130 to be described later with each other. As a heat exchange device, repeated expansion and contraction occurs while cooling or heating according to the inflow of a gas stream. In general, a heat exchange device is made of a material such as a metal with good conductivity in order to promote heat exchange efficiency. As such expansion and contraction occur repeatedly, the durability of the equipment is deteriorated, and there is a risk of cracking of various welding parts. there is a problem with Therefore, when the reliquefaction line 130 to be described later operates, the BOG introduced into the BOG supply line 120 must be passed through the heat exchanger 132 to improve the reliquefaction efficiency of BOG, but the reliquefaction line When 130 does not work, it is required to bypass the heat exchanger 132 to achieve durability of the heat exchanger 132 .

Accordingly, the BOG supply line 120 may include a BOG bypass line 122 in which the introduced BOG bypasses the heat exchanger 132 of the reliquefaction line 130 and supplies it to a buffer tank 190 to be described later. there is. The boil-off gas bypass line 122 has an inlet end branching from the front end of the heat exchanger 132 on the boil-off gas supply line 120 , and an outlet end joining the rear end of the heat exchanger 132 on the boil-off gas supply line 120 . As a result, the boil-off gas can be directly supplied to the buffer tank 190 to be described later by bypassing it without passing through the heat exchanger 132 .

The boil-off gas supply line 120 includes a first flow rate control valve 125 for controlling the flow rate of boil-off gas passing through the heat exchanger 132 and a buffer tank 190 to be described later through the boil-off gas bypass line 122 . It may include a second flow rate control valve 126 for controlling the flow rate of the directly supplied boil-off gas. The first and second flow control valves 125 and 126 may be controlled to alternately open and close operations, and depending on the amount of boil-off gas generated in the storage tank 110, whether the vessel is sailing full or empty, etc. The opening/closing operation may be manually performed by an operator or the opening/closing operation may be automatically controlled by the control unit.

On the other hand, in order to improve the operation efficiency of the first compressor 121a of the first compression unit 121 and the durability of the product, it is required to maintain the temperature of the boil-off gas introduced thereto within a predetermined range. In general, a compressor that receives gas and operates to pressurize or compress is operated and controlled so that the pressure level at the outlet or downstream is kept constant. When the temperature is high, the density of the gas flow is relatively low, so a relatively large flow rate or volume of the gas flow is sucked. Conversely, when the temperature of the incoming gas flow is low, the density of the gas flow is relatively high, so the operation is performed by sucking a relatively small flow rate or volume of the gas flow. Therefore, if the temperature or flow rate of the gas flow entering the compressor changes rapidly, or if the pressure closely related to the density of the gas flow changes rapidly, the pressurization efficiency or operation efficiency of the compressor decreases, or the compressor becomes overloaded. There is a risk of deterioration of durability. In addition, there is a risk of safety accidents due to residual gas flow in the emergency stop of the compressor, and there is a problem in that the operation stability of the ship is deteriorated as the supply of fuel gas to the engine is stopped.

In the case of a full voyage with a sufficient amount of liquefied natural gas in the storage tank 110 after receiving liquefied natural gas from a supply source such as a natural gas production area, the amount of boil-off gas is also increased, so the re-liquefaction line 130 to be described later operates. Accordingly, the boil-off gas flowing into the boil-off gas supply line 120 and entering the first compressor 121a is heated while passing through a heat exchanger 132 to be described later, so that the temperature is relatively high and the flow rate is large. Conversely, in the case of an airship voyage in which liquefied natural gas is unloaded at a consumer such as a port and only a minimum of liquefied natural gas is stored in the storage tank 110 for the operation of the ship, the amount of BOG is very small, so the re-liquefaction line ( 130) does not need to operate, and accordingly, the boil-off gas flowing into the boil-off gas supply line 120 and entering the first compressor 121a does not undergo a heat exchange process, so the temperature is relatively low and the flow rate is small. . In this way, the temperature and flow rate of BOG flowing into the first compressor 121a varies depending on the ship's operating condition or the amount of liquefied natural gas loaded in the storage tank 100. As the boil-off gas is directly supplied to the first compression unit 121 without passing through the heat exchanger 132 through the line 122 , the temperature of the boil-off gas flowing into the first compressor 121a changes.

Therefore, despite the rapid temperature change or flow rate change of the boil-off gas generated depending on whether the reliquefaction line 130 to be described later operates or whether the gas flow of the boil-off gas bypass line 122 to be described later passes or not, the first compressor 121a) A method of maintaining the temperature, flow rate, or pressure of the BOG introduced therein within a certain range is required for the stable operation of the evaporator.

Accordingly, a buffer tank 190 is provided at the front end of the first compression unit 121 on the boil-off gas supply line 120 , and the temperature change and flow rate change of the boil-off gas flowing into the first compressor 121a of the first compression unit 121 . And it is provided to buffer at least one of the pressure change.

The buffer tank 190 may be disposed between the front end of the first compression unit 121 and the rear end of the heat exchanger 132 on the boil-off gas supply line 120 , and is provided to accommodate boil-off gas therein. The buffer tank 190 may be provided as a pressurized tank insulated so that the BOG introduced thereto can stably accommodate the BOG in various ranges of temperature, flow rate and pressure level, but is not limited to the structure. The buffer tank 190 is disposed at the front end of the first compression unit 121 to form a space for accommodating and mixing the boil-off gas. Sudden changes in temperature, pressure, flow rate, etc. can be buffered. For example, during a full voyage, the BOG flowing into the BOG supply line 120 passes through the heat exchanger 132 and the BOG upstream of the first compression unit 121 has a relatively high temperature and a large flow rate. The buffer tank 190 transfers the BOG exceeding the storage amount to the first compression unit 121 while temporarily accommodating the BOG having a high temperature and a large flow rate as described above. When the boil-off gas is later switched to ballistic sailing or the boil-off gas is supplied to the boil-off gas bypass line 122 , the temperature of the boil-off gas existing on the upstream side of the first compression unit 121 is lowered or the flow rate is reduced. At this time, since the pre-introduced relatively high-temperature BOG is accommodated in the buffer tank 190 at this time, even if the temperature of the BOG on the upstream side of the first compression unit 121 drops or the flow rate decreases, the buffer tank 190 ) by mixing these boil-off gases with each other, it is possible to prevent a sudden change in the temperature, flow rate, or pressure of the boil-off gas flowing into the first compression unit 121 .

Conversely, when the boil-off gas is supplied to the ballast sailing or the boil-off gas bypass line 122, the heat exchange process does not occur in the boil-off gas upstream of the first compression unit 121, so that the temperature is relatively low or the flow rate is small. The buffer tank 190 transfers the BOG exceeding the storage amount to the first compression unit 121 while temporarily accommodating the BOG having a low temperature and a low flow rate as described above. As the boil-off gas is later switched to full sailing or supplied via the heat exchanger 132 , the temperature of the boil-off gas on the upstream side of the first compression unit 121 rises or the flow rate increases. At this time, since the pre-introduced BOG having a relatively low temperature is accommodated in the buffer tank 190 at this time, even if the temperature of BOG on the upstream side of the first compression unit 121 increases or the flow rate increases, the buffer tank 190 ) by mixing these boil-off gases with each other, it is possible to prevent a sudden change in the temperature, flow rate, or pressure of the boil-off gas flowing into the first compression unit 121 . In this way, the buffer tank 190 is introduced into the boil-off gas supply line 120 and temporarily accommodates the boil-off gas before being delivered to the first compression unit 121, so that the operation environment of the ship or the operating conditions of various facilities is changed. By buffering the sudden change in temperature and flow rate of the boil-off gas, as well as the pressure change, the operating efficiency of the first compressor 121a can be improved, and durability and structural stability of the equipment can be achieved.

On the other hand, when the amount of boil-off gas accommodated or generated in the storage tank 110 is very small, such as on an airship sailing, stable and continuous operation of the engine 10 may be difficult, and the internal pressure of the storage tank 110 is excessively lowered, thereby affecting structural stability. There is a risk of influence. In this case, the liquefied natural gas accommodated in the storage tank 110 should be able to be utilized as the fuel gas of the engine 10 .

Accordingly, a vaporized gas supply line 190 is provided to vaporize the liquefied natural gas accommodated in the storage tank 110 and supply it to the buffer tank 190 .

The vaporized gas supply line 190 has an inlet side end disposed on the inner lower side of the storage tank 110, and a delivery pump 191 for pressurizing and sending out liquefied natural gas may be provided, and the outlet end end of the buffer tank ( 180), a vaporizer 192 for heating and vaporizing the liquefied natural gas pressurized and transferred by the delivery pump 191 may be provided at the middle portion. The vaporization gas supply line 190 stops the operation for energy efficiency when the operation of the engine 10 is sufficient with only the boil-off gas because the amount of boil-off gas generated is sufficient, such as in full sailing. When it is difficult to operate the engine 10 only with gas, the operation may be started.

On the other hand, in general, a pump for pressurizing a liquid can quickly change the flow rate or pressure of a target fluid delivered according to a change in engine output, whereas a compressor for pressurizing a gas can change the flow rate of a target fluid delivered according to a change in engine output. Alternatively, the change in pressure is relatively slow compared to the pump. Therefore, when the pump and the compressor are connected in series, the flow rate may stagnate between the pump and the compressor, and accordingly, the internal pressure of the pipeline and various facilities disposed between the pump and the compressor increases, resulting in structural stability of the facility and durability may be reduced.

Accordingly, in the gas management system 100 of the ship according to the present embodiment, as described above, a buffer tank 190 is provided at the front end of the first compression unit 121 to temporarily accommodate boil-off gas, and then the first compression unit ( 121) is supplied to the first compressor 121a, even if an output change of the engine 10 occurs while the delivery pump 191 of the vaporized gas supply line 190 is operating, the delivery pump 191 and the first compressor It is possible to reduce the phenomenon of boil-off gas stagnation between (121a). In addition, even when the pressure of boil-off gas rapidly changes depending on whether the delivery pump 191 is operated, it can be stably buffered and supplied to the first compressor 121a.

The liquefied gas spray line 195 is provided to adjust the internal temperature of the buffer tank 180 . When the internal temperature of the buffer tank 180 is higher than a certain range, the liquefied gas spray line 195 may lower the internal temperature of the buffer tank 180 by spraying liquefied natural gas into the buffer tank 180 . . For this, the liquefied gas spray line 195 has an inlet end branched between the delivery pump 191 and the vaporizer 192 on the vaporized gas supply line 190, and the outlet end is connected to the inside of the buffer tank 180 However, a plurality of spray nozzles 196 may be disposed for uniform spraying of liquefied natural gas.

When the liquefied gas spray line 195 is operated, the internal temperature of the buffer tank 180 is lowered, and accordingly, a portion of the boil-off gas is liquefied in the buffer tank 180 to generate a liquid component. When droplets are introduced into the compressor, the lifespan and operating efficiency of the device are adversely affected, so it is required to remove the liquid component generated inside the buffer tank 180 without fail. Accordingly, the droplet removal line 181 may remove the liquid component generated and present in the buffer tank 180 and recover it to the storage tank 110 . To this end, the inlet side end of the droplet removal line 181 may be connected to the inner lower side of the buffer tank 180 , and the outlet side end may be connected to the inside of the storage tank 110 .

The re-liquefaction line 130 passes through the first compression unit 121 of the boil-off gas supply line 120 and is provided to receive a portion of the pressurized boil-off gas and re-liquefy it.

The reliquefaction line 130 includes a second compression unit 131 for additionally pressurizing the introduced BOG, and a heat exchanger 132 for cooling the pressurized BOG while passing through the first and second compression units 121 and 131. ), the first gas-liquid separator 133 that receives the boil-off gas cooled through the heat exchanger 132 and separates it into a gas component and a liquid component, and a gas component that transfers the gas component of the first gas-liquid separator 133 The circulation line 134 and the expander 135 provided in the gas component circulation line 134 to depressurize the gas component of the first gas-liquid separator 133, and the liquid component for discharging the liquid component of the first gas-liquid separator 133 A second gas-liquid separator 137 that receives the vaporized gas in a gas-liquid mixed state supplied along the circulation line 136 and the gas component circulation line 134 and the liquid component circulation line 136 but separates it into a liquid component and a gas component. And, the gas component recovery line 138 for supplying the gas component of the second gas-liquid separator 137 to the storage tank 110 or the boil-off gas supply line 120, and the liquid component of the second gas-liquid separator 137 is stored A portion of the boil-off gas pressurized by the liquid component recovery line 139 and the second compression unit 131 supplied to the tank 110 is directly supplied to the first gas-liquid separator 133 by bypassing the heat exchanger 132 . The saturation control line 150, the third flow control valve 151 for controlling the flow rate of the gas flow transferred along the saturation control line 150, and the first gas-liquid separator 133 to detect the level of the liquid component and a portion of the boil-off gas pressurized by the level sensor L and the second compression unit 131 to bypass the heat exchanger 132 and the first gas-liquid separator 133 and directly supply to the front end side of the expander 135 Temperature sensing the temperature of the liquefaction control line 160, the fourth flow control valve 161 for controlling the flow rate of the gas flow transferred along the liquefaction control line 160, and the gas flow flowing into the expander 135 The sensor T, the emergency circulation line 170 for supplying the excess gas flow on the reliquefaction line 130 to the front end of the expander 135 when the operation of the reliquefaction line 130 is stopped, and the emergency circulation line 170 ) It may be provided to include a fifth flow rate control valve 171 for controlling the flow rate of the gas flow transferred along the, and a pressure sensor (P) for detecting the pressure of the gas flow at the front end of the expander 135.

The second compression unit 131 is provided to additionally pressurize the boil-off gas flowing into the reliquefaction line 130 . BOG flowing into the reliquefaction line 130 is primarily pressurized by the first compression unit 121, but is secondary by the second compression unit 131 in order to improve the reliquefaction efficiency of the BOG. can be further pressurized. The second compression unit 131 may include a second compressor 131a for compressing the boil-off gas flowing into the reliquefaction line 130 and a second cooler 131b for cooling the boil-off gas heated while being compressed. . In FIG. 1 , the second compressor 131a and the second cooler 131b are illustrated as being arranged in three stages, but this is an example of the second compressor 131a according to the specification of the second compressor 131a or the required pressurization range of the boil-off gas. The compressor 131a and the second cooler 131b may be formed in various numbers.

The second compressor 131a of the second compression unit 131 may be provided as a compander 140 together with an expander 135 to be described later, and a detailed description thereof will be provided later.

The heat exchanger 132 is provided to cool the boil-off gas pressurized by the first compression unit 121 and the second compression unit 131 . The heat exchanger 132 exchanges heat with the boil-off gas that has been further pressurized through the second compression unit 131 on the reliquefaction line 130 and the boil-off gas of low temperature before being pressurized flowing into the boil-off gas supply line 120 , The boil-off gas pressurized by the first compression unit 121 and the second compression unit 131 may be cooled. Since the BOG flowing into the heat exchanger 132 on the reliquefaction line 130 is compressed while passing through the first compression unit 121 and the second compression unit 131, the temperature and pressure are increased, so the BOG supply line By heat-exchanging with the low-temperature BOG before passing through the first compression unit 121 on the upper portion 120, the high-temperature pressurized BOG transferred along the reliquefaction line 130 can be cooled. As described above, since the pressurized BOG can be cooled without a separate cooling device by the heat exchanger 132, unnecessary waste of power is prevented, the facility is simplified, and the efficiency of facility operation can be promoted.

A first shutoff valve 130a for allowing and blocking the flow of boil-off gas flowing into the heat exchanger 132 along the reliquefaction line 130 may be provided at the front end of the heat exchanger 132 on the reliquefaction line 130 . there is. The first shut-off valve 130a is opened during normal operation of the reliquefaction line 130 to allow the flow of boil-off gas from the second compression unit 131 to the heat exchanger 132, but the reliquefaction line 130 It is closed when the operation is stopped to block the flow of the pressurized BOG from the second compression unit 131 to the heat exchanger 132 . The opening and closing operation of the first shut-off valve 130a may be controlled manually by an operator or automatically by a control unit.

The first gas-liquid separator 133 is provided to separate the boil-off gas in a gas-liquid mixed state cooled by passing through the heat exchanger 132 into a gas component and a liquid component. As the pressurized BOG is cooled while passing through the heat exchanger 132, some re-liquefaction is performed, but an unliquefied gas component may also exist. Accordingly, the first gas-liquid separator 133 receives the boil-off gas cooled by passing through the heat exchanger 132 , and separates it into a gas component and a liquid component to facilitate easy handling and management of each component.

The first gas-liquid separator 133 may be provided with a level sensor (L) for detecting the level of the separated liquid component, and the control unit is the liquid component level information of the first gas-liquid separator 133 detected by the level sensor (L) It is possible to control the opening and closing operations of the third flow control valve 151 of the saturation control line 150 and the pressure reducing valve 136a of the liquid component circulation line 136, which will be described later, based on the above. A detailed description thereof will be provided later.

The gas component circulation line 134 is provided to transfer the gas component separated in the first gas-liquid separator 133 . To this end, the gas component circulation line 134 has an inlet end that communicates with the upper inner side of the first gas-liquid separator 133, and an outlet end joins a liquid component circulation line 136 to be described later, and the second gas-liquid separator 137 ), and an expander 135 is provided in the gas component circulation line 134 to depressurize and expand the gas component transferred along the gas component circulation line 134 to deliver it to the second gas-liquid separator 137 . In addition, in the gas component circulation line 134, a temperature sensor (T) for detecting the temperature of the gas flow flowing into the expander 135 and a pressure sensor (P) for detecting the pressure of the gas flow at the front end of the expander 135 are provided. The counter flow of the gas flow between the point where the liquid component circulation line 136, which will be described later, joins and the expander 135, specifically, the expander 135 from the second gas-liquid separator 137 or the liquid component circulation line 136 A check valve (134a) for preventing the gas flow from occurring to the side may be provided.

A second shut-off valve 130b for allowing and blocking the flow of gas components flowing from the first gas-liquid separator 133 to the gas component circulation line 134 may be provided on the inlet side of the gas component circulation line 134 . The second shut-off valve 130b is opened during normal operation of the reliquefaction line 130 to allow the flow of gas components flowing from the first gas-liquid separator 133 to the gas component circulation line 134, but the reliquefaction line It is closed when the operation of the 130 is stopped to block the flow of the gas component transferred from the first gas-liquid separator 133 to the expander 135 along the gas component circulation line 134 . The opening/closing operation of the second shut-off valve 130b may be controlled manually by an operator or automatically by a control unit.

The expander 135 is provided to depressurize and expand the gas component separated from the first gas-liquid separator 133 and transferred along the gas component circulation line 134 . The gas component transferred along the gas component circulation line 134 is in a pressurized state by the first compression unit 121 and the second compression unit 131. As the expander 135 depressurizes the pressurized gas component, Reliquefaction of the gas component can be realized by cooling and expansion. The expander 135 may reduce the gas component to a pressure level corresponding to the internal pressure of the second gas-liquid separator 137 or the storage tank 110 .

The second compressor 131a and the expander 135 of the second compression unit 131 may be provided as a turbine-type compander 140 (Compander). Specifically, the compander 140 transfers the rotational kinetic energy of the turbine as an expansion force generated when the expander 135 adiabatically expands the boil-off gas to the second compressor 131a connected through the rotation shaft to the second compression unit 131 . ) can perform the pressurization process of boil-off gas. As described above, by providing the second compressor 131a and the expander 135 of the second compression unit 131 for pressurizing the boil-off gas as the compander 140, the efficiency of facility operation can be improved.

The liquid component circulation line 136 is cooled and reliquefied while passing through the heat exchanger 132 and is provided to supply the liquid component separated in the first gas-liquid separator 133 to the second gas-liquid separator 137 to be described later. To this end, the inlet side end of the liquid component circulation line 136 communicates with the inner lower side of the first gas-liquid separator 133 , and the outlet side end joins the gas component circulation line 134 and is connected to the second gas-liquid separator 137 . can be connected

The liquid component circulation line 136 may be provided with a pressure reducing valve 136a for controlling and reducing the flow rate of the liquid component transferred along it. The operation of the pressure reducing valve 136a may be controlled based on the liquid component level information of the first gas-liquid separator 133 detected by the level sensor L. As described above, the liquid component separated from the first gas-liquid separator 133 while being transported along the reliquefaction line 130 is in a state in which the pressure is increased by the first compression unit 121 and the second compression unit 131 . Bar, the pressure reducing valve 136a may implement cooling and expansion by depressurizing the liquid component separated in the first gas-liquid separator 133 . The pressure reducing valve 136a may be, for example, a Joule-Thomson valve, and may be reduced to a pressure level corresponding to the pressure of the gas component decompressed through the expander 135 or the internal pressure of the storage tank 110 . The liquid component can be decompressed.

On the other hand, natural gas is a mixture containing heavy hydrocarbons such as ethane (C2H6), propane (Propane, C3H8), butane (C4H10) in addition to the main component methane (Methane, CH4). Among them, the liquefaction point of methane (CH4) is about -162 ℃, the liquefaction point of ethane (C2H6), a heavy hydrocarbon, is about -88.6 ℃, and the liquefaction point of propane (C3H8) is about -42 ℃, etc. It has a higher liquefaction point than (CH4). Accordingly, as the reliquefaction process of boil-off gas through the reliquefaction line 130 continues, a large amount of heavy hydrocarbon components having a relatively high liquefaction point are contained in the liquid component inside the first gas-liquid separator 133 . As will be described later, in order to form the interior of the first gas-liquid separator 133 in a saturated state in order to maximize the reliquefaction efficiency of the boil-off gas and the operation efficiency of the expander 135, a specific pressure is applied to the inside of the first gas-liquid separator 133. Or you have to set it to a specific temperature. Therefore, basically, the pressure reducing valve 136a is closed to seal the inside of the first gas-liquid separator 133 to promote the formation of a saturated state, but when a heavy hydrocarbon component having a relatively high liquefaction point is contained in a large amount in the liquid component, saturation to be described later Since the level of the liquid component of the first gas-liquid separator 133 is not controlled even by the control line 150 , the controller opens the pressure reducing valve 136a at this time to open the first gas-liquid separator 133 and the liquid separated and accumulated inside the first gas-liquid separator 133 . ingredients can be expelled.

Specifically, when the liquid component level of the first gas-liquid separator 133 detected by the level sensor L is higher than a preset level, the control unit contains a large amount of heavy hydrocarbon liquid component inside the first gas-liquid separator 133 It is determined that it is possible to control the operation of the pressure reducing valve (136a) in a direction to increase the discharge of the liquid component through the liquid component circulation line (136). Accordingly, by discharging the heavy hydrocarbon component accumulated in the first gas-liquid separator 133 , it is possible to smoothly and quickly form a saturated state of the first gas-liquid separator 133 . Conversely, when the level of the liquid component in the first gas-liquid separator 133 sensed by the level sensor L is lower than the preset level, the control unit reduces the pressure in a direction to reduce the discharge of the liquid component through the liquid component circulation line 136 . By controlling the operation of the valve (136a), it is possible to easily and quickly form a saturated state in the interior of the first gas-liquid separator (133). A detailed description of the configuration of forming the interior of the first gas-liquid separator 133 in a saturated state or adjusting the gas component of the first gas-liquid separator 133 to a saturation temperature will be described later.

The second gas-liquid separator 137 receives the boil-off gas in a gas-liquid mixed state supplied from the gas component circulation line 134 and the liquid component circulation line 136 , but is provided to separate the gas component into a gas component and a liquid component. Most of the gas component of the first gas-liquid separator 133 is reliquefied as it is reduced and cooled by passing through the expander 135 , but gas components such as flash gas may be generated during the decompression process. In addition, as the liquid component of the first gas-liquid separator 133 is decompressed through the pressure reducing valve 136a, some gas components may be generated. Accordingly, the second gas-liquid separator 137 receives the gas flow respectively transferred along the gas component circulation line 134 and the liquid component circulation line 136, but separates it into a gas component and a liquid component for easy handling of each component and management can be facilitated.

The liquid component recovery line 139 may connect the second gas-liquid separator 137 and the storage tank 110 to re-supply the liquid component separated by the second gas-liquid separator 137 to the storage tank 110 . The liquid component recovery line 139 may have an inlet-side end connected to an inner lower side of the second gas-liquid separator 137 , and an outlet-side end connected to the inside of the storage tank 110 . The liquid component recovery line 139 may be provided with an on/off valve (not shown) for controlling the supply amount of the liquid component recovered to the storage tank 110 . The opening and closing degree of the opening/closing valve may be controlled according to the liquid component level of the second gas-liquid separator 137 .

The gas component recovery line 138 includes a second gas-liquid separator 137 and a storage tank ( 110) or the second gas-liquid separator 137 and the boil-off gas supply line 120 may be provided. In FIG. 1 , the gas component recovery line 138 supplies the gas component of the second gas-liquid separator 137 to the front end of the first compression unit 121 on the boil-off gas supply line 120 , but in addition to this, the second This includes all cases of supplying from the gas-liquid separator 137 to the storage tank 110 , or re-supplying together to the boil-off gas supply line 120 and the storage tank 110 side. The gas component recovery line 138 may be provided with an opening/closing valve (not shown) for controlling the flow rate of the gas component recovered to the storage tank 110 or the boil-off gas supply line 120 , and the opening/closing valve is the second gas-liquid separator. Depending on the internal pressure value of (137), the degree of opening and closing can be controlled.

On the other hand, in depressurizing the gas component through the expander 135, when the gas component enters the expander 135 from saturation, the reliquefaction efficiency of BOG can be improved, and further, the Operational efficiency can be improved. Accordingly, a portion of the boil-off gas pressurized through the second compression unit 131 is bypassed by the heat exchanger 132 so that the saturation control line 150 forms the interior of the first gas-liquid separator 133 in a saturated state, and the first gas-liquid It can be directly supplied to the separator 133 .

In order to form the interior of the first gas-liquid separator 133 in a saturated state, the internal temperature of the first gas-liquid separator 133, specifically, the gas component of the first gas-liquid separator 133 must reach the saturation temperature. However, as described above, natural gas is a mixture containing methane (CH4), ethane (C2H6), propane (C3H8), butane (C4H10), etc., generated in the storage tank 110 to the reliquefaction line 130 As the component content of the incoming BOG frequently changes, a specific temperature value forming the inside of the first gas-liquid separator 133 in a saturated state also changes, and furthermore, the BOG supply line for performing heat exchange in the heat exchanger 132 . As the flow rate of BOG on 120 and the flow rate of BOG on the reliquefaction line 130 change frequently, the temperature of the gas component separated in the first gas-liquid separator 133 also changes frequently. Accordingly, the saturation control line 150 bypasses the heat exchanger 132 and directly supplies a portion of the boil-off gas pressurized through the second compression unit 131 to the first gas-liquid separator 133 , so that the first gas-liquid separator 133 ) can induce the gas component separated and accommodated in the saturation temperature.

The saturation control line 150 has an inlet end branched between the rear end of the second compression unit 131 on the reliquefaction line 130 and the heat exchanger 132 , and an outlet end end of the first gas-liquid separator 133 . A third flow control valve 151 for controlling the flow rate of the gas flow transferred along the saturation control line 150 may be provided.

The opening and closing operation of the third flow control valve 151 may be controlled based on the liquid component level information of the first gas-liquid separator 133 detected by the level sensor L. In the saturated state, since the gas component is maximally accommodated in the first gas-liquid separator 133, the level of the liquid component is also maintained within a certain range. Therefore, the control unit controls the opening or closing operation of the third flow control valve 151 based on the liquid component level information of the first gas-liquid separator 133 sensed by the level sensor L to control the opening or closing operation of the first gas-liquid separator 133. can lead to saturation of the interior of As described above, as the boil-off gas contains various components such as methane (CH4), ethane (C2H6), propane (C3H8), the numerical range forming the saturation temperature according to the content of each component is wide, so the control unit controls the gas flow When controlling the operation of the third flow control valve 151 based on the temperature information of , it is difficult to accurately control the saturation state or the saturation temperature. Therefore, the control unit can control the opening and closing operation of the third flow rate control valve 151 based on the level information of the liquid component separated in the first gas-liquid separator 133, not the temperature information of the gas flow for quick and accurate control. there is.

Specifically, when the level of the liquid component in the first gas-liquid separator 133 detected by the level sensor L is higher than a preset level, the control unit increases the amount of generation of liquefied components because the internal temperature of the first gas-liquid separator 133 is low. It is determined that there is, it is possible to control the operation of the third flow rate control valve 151 in the direction of increasing the gas flow through the saturation control line (150). As a result, the internal temperature of the first gas-liquid separator 133 and the temperature of the gas component may be gradually increased to form a saturated state or a saturated temperature. Conversely, when the liquid component level of the first gas-liquid separator 133 sensed by the level sensor L is lower than a preset level, the control unit increases the internal temperature of the first gas-liquid separator 133 to increase the amount of gas component generated. It is determined that it is possible to control the operation of the third flow rate control valve 151 in a direction to reduce the gas flow through the saturation control line 150 . Accordingly, the internal temperature of the first gas-liquid separator 133 and the temperature of the gas component may be gradually lowered to form a saturated state or a saturated temperature.

In the expander 135, when the gas component transferred along the gas component circulation line 134 is decompressed, reliquefaction occurs at the rear end of the expander 135 to generate droplets. vibration and noise may occur, and furthermore, there is a risk of damage to the turbine of the expander 135 . Therefore, there is a need to adjust the amount of droplets not to exceed the allowable droplet amount when the expander 135 is operated. Accordingly, it is possible to prevent vibration and noise generated during operation of the expander 135 by controlling the flow rate of the liquid droplets that are reliquefied while the liquefaction control line 160 passes through the expander 135 and to improve the durability of the device.

The liquefaction control line 160 bypasses the heat exchanger 132 and the first gas-liquid separator 133 for a portion of the boil-off gas additionally pressurized by the second compression unit 131, and the expander ( 135) It is provided to supply directly to the front end. To this end, the liquefaction control line 160 has an inlet end branched between the rear end of the second compression unit 131 on the reliquefaction line 130 and the heat exchanger 132 , and an outlet end end of the gas component circulation line 134 . It may be connected to the front end of the expander 135 of the upper chamber, and a fourth flow control valve 161 for controlling the flow rate of the gas flow transferred along the liquefaction control line 160 may be provided.

The opening/closing operation of the fourth flow control valve 161 may be controlled based on the temperature information of the gas component on the gas component circulation line 134 flowing into the expander 135 . As described above, the gas component is transferred to the expander 135 after the interior of the first gas-liquid separator 133 is formed in a saturated state. this increases Accordingly, the control unit controls the opening or closing operation of the fourth flow control valve 161 based on the temperature information of the gas flow at the front end of the expander 135 on the gas component circulation line 134 sensed by the temperature sensor T. , the amount of droplets generated at the rear end of the expander 135 can be adjusted. Specifically, when the temperature of the gas flow at the front end of the expander 135 sensed by the temperature sensor T is lower than a preset level, the controller may control the amount of droplets generated while passing through the expander 135 as the allowable liquid of the expander 135 . It is determined that it is highly likely that the appropriate amount will be exceeded, and the operation of the fourth flow control valve 161 may be controlled in a direction to increase the high-temperature gas flow through the liquefaction control line 160 . As a result, the temperature of the gas component or gas flow toward the expander 135 may be partially increased to adjust the droplet generation amount after passing through the expander 135 to be less than an allowable droplet amount. Conversely, when the temperature of the gas flow at the front end of the expander 135 is higher than a preset level, it is determined that the amount of droplets generated while passing through the expander 135 is lower than the allowable droplet amount of the expander 135, so that the liquefaction control line 160 ) can control the operation of the fourth flow control valve 161 in the direction of reducing the high-temperature gas flow through. Accordingly, the reliquefaction efficiency of the boil-off gas by the expander 135 and the operating efficiency of the expander 135 can be maximized by lowering the temperature of the gas component or the gas flow toward the expander 135 as much as possible.

On the other hand, in this embodiment and drawings, the fourth flow control valve 161 is illustrated and described as controlling the opening/closing operation based on the temperature information of the gas component or gas flow supplied to the expander 135, but in addition to the expander ( 135) The amount of droplets generated at the rear end may be sensed or the opening/closing operation of the fourth flow control valve 161 may be controlled based on noise and vibration information generated from the expander 135 . In addition, when the flow rate of the gas component supplied to the expander 135 is small, even if the temperature of the gas component is low, the droplet amount is not excessively generated after passing through the expander 135 , so the expander along the gas component circulation line 134 Based on the flow rate information of the gas component transferred to the (135) side, it may be controlled to close the fourth flow rate control valve 161 when it is lower than a preset flow rate level.

The emergency circulation line 170 is provided to supply the excess gas flow on the reliquefaction line 130 to the front end side of the expander 135 when the reliquefaction line 130 is stopped.

When the operation of the reliquefaction line 130 is stopped, the first shutoff valve 130a and the second shutoff valve 130b are closed to block the gas flow from flowing into the heat exchanger 132 and the gas component circulation line 134 . At the same time, the pressure reducing valve 136a is opened, and the liquid component separated in the first gas-liquid separator 133 is transferred to the second gas-liquid separator 137 side. At this time, in the case of the second compressor 131a of the second compression unit 131, it is circulated through a circulation line (not shown) so that the high-pressure gas flow can be stably processed, but in the case of the expander 135, the operation is stopped. As the gas flow at the front end is sucked during the process, a vacuum is formed between the front end of the expander 135 and the second shut-off valve 130b on the gas component circulation line 134, so that the pipe may be damaged or the expander 135 may be damaged. can

Accordingly, after the emergency circulation line 170 stops the operation of the re-liquefaction line 130 , the excess gas flow on the re-liquefaction line 130 , specifically, the excess boil-off gas pressurized by passing through the second compression unit 131 is released into the expander. (135) It is possible to prevent the front end of the expander 135 from being formed in a vacuum by supplying it to the front end side. To this end, the emergency circulation line 170 has an inlet end connected between the rear end of the second compression unit 131 and the first shutoff valve 130a on the reliquefaction line 130, and an outlet end of the gas component circulation line ( 134) may be connected between the rear end of the second shutoff valve 130b and the front end of the expander 135, and a fifth flow rate control valve 171 that controls the flow rate of the gas flow transferred along the emergency circulation line 170. can be provided.

The opening and closing operation of the fifth flow control valve 171 may be controlled based on the pressure information of the gas flow at the front end of the expander 135 . Specifically, when the pressure of the gas flow at the front end of the expander 135 sensed by the pressure sensor P is lower than a preset level, the control unit generates a vacuum at the front end of the expander 135 when the reliquefaction line 130 stops operating. It is determined that there is a high possibility that it is possible to control the operation of the fifth flow rate control valve 171 in a direction to increase the gas flow through the emergency circulation line 170 . Accordingly, it is possible to prevent a vacuum from being formed in pipes such as the gas component circulation line 134 by supplying the excess gas flow to the front end of the expander 135 . Conversely, when the pressure of the gas flow at the front end of the expander 135 is higher than a preset level, it is determined that the expander 135 can also be stably stopped despite the operation of the reliquefaction line 130 being stopped. It is possible to control the operation of the fifth flow rate control valve 171 in the direction of reducing the gas flow through the emergency circulation line 170 to prevent the gas flow.

100: fuel gas management system 110: storage tank
120: boil-off gas supply line 121: first compression unit
122: boil-off gas bypass line 125: first flow control valve
126: second flow control valve 130: re-liquefaction line
131: second compression unit 132: heat exchanger
133: first gas-liquid separator 134: gas component circulation line
135: expander 136: liquid component circulation line
136a: pressure reducing valve 137: second gas-liquid separator
138: gas component recovery line 139: liquid component recovery line
140: compander 150: saturation control line
151: third flow control valve 160: liquefaction control line
161: fourth flow control valve 170: emergency drive line
171: fifth flow control valve 180: buffer tank
181: droplet removal line 190: vaporized gas supply line
191: delivery pump 192: carburetor
195: liquefied gas spray line

Claims (14)

at least one storage tank for accommodating liquefied gas and boil-off gas;
a boil-off gas supply line provided with a first compression unit for pressurizing the boil-off gas in the storage tank and supplying the boil-off gas pressurized by the first compression unit to the engine;
a reliquefaction line provided with a heat exchanger for receiving a portion of the BOG pressurized by the first compression unit and cooling the BOG by heat exchange with a relatively low temperature BOG transported along the BOG supply line; and
A ship including a buffer tank provided between the heat exchanger and the first compression unit on the boil-off gas supply line to buffer at least any one of a temperature change, a flow rate change, and a pressure change of the boil-off gas flowing into the first compression part gas management system. According to claim 1,
The gas management system of a ship further comprising a vaporization gas supply line for supplying the buffer tank by vaporizing the liquefied gas of the storage tank. 3. The method of claim 2,
The vaporized gas supply line is
A gas management system for a ship comprising: a delivery pump for pressurizing and delivering the liquefied gas of the storage tank; and a vaporizer for vaporizing the liquefied gas transferred by the delivery pump. 4. The method of claim 3,
Gas management system of a ship further comprising a liquefied gas spray line for controlling the internal temperature of the buffer tank. 5. The method of claim 4,
The gas management system of a ship further comprising a droplet removal line for recovering the liquid component generated inside the buffer tank to the storage tank. 5. The method of claim 4,
The liquefied gas spray line is
The inlet end is branched from the rear end of the delivery pump on the vaporized gas supply line,
A gas management system of a ship provided with a spray nozzle having an outlet side end disposed inside the buffer tank. 3. The method of claim 2,
The boil-off gas supply line is
The gas management system of a ship including a boil-off gas bypass line for supplying the boil-off gas of the storage tank to the buffer tank, bypassing the heat exchanger and supplying the boil-off gas. 8. The method of claim 7,
The boil-off gas supply line is
A first flow rate control valve for controlling the flow rate of boil-off gas supplied to the buffer tank via the heat exchanger, and a second flow rate control valve for adjusting the flow rate of boil-off gas supplied to the buffer tank through the boil-off gas bypass line A ship's gas management system further comprising a. 3. The method of claim 2,
The first compression unit
A gas management system for a ship comprising: at least one first compressor; and at least one first cooler cooling the boil-off gas compressed and heated by the first compressor. 3. The method of claim 2,
The reliquefaction line is
A second compression unit that additionally pressurizes the incoming BOG and delivers it to the heat exchanger, a first gas-liquid separator that receives BOG cooled by the heat exchanger and separates it into a gas component and a liquid component, and the first gas-liquid separator. A gas management system for a ship, comprising: a gas component circulation line for transferring a gas component; and an expander provided in the gas component circulation line to reduce the gas component of the first gas-liquid separator. 11. The method of claim 10,
The reliquefaction line is
A second gas-liquid separator that receives the boil-off gas in a gas-liquid mixed state decompressed by the expander and separates it into a gas component and a liquid component, and a liquid component circulation line for supplying the liquid component of the first gas-liquid separator to the second gas-liquid separator And, a gas component recovery line for supplying the gas component of the second gas-liquid separator to the front end of the first compression unit on the storage tank or the boil-off gas supply line, and supplying the liquid component of the second gas-liquid separator to the storage tank The fuel gas management system of the ship further comprising a liquid component recovery line. 12. The method of claim 11,
The reliquefaction line is
The fuel gas management system of a ship further comprising a pressure reducing valve for reducing the pressure of the liquid component transferred along the liquid component circulation line. 11. The method of claim 10,
The second compression unit includes at least one second compressor,
The second compressor and the expander are
A fuel gas management system for a ship in which the second compressor is provided as a compander that pressurizes boil-off gas by the expansion force of the expander. 14. The method of claim 13,
The second compression unit
The fuel gas management system of a ship further comprising at least one second cooler for cooling the boil-off gas compressed and heated by the second compressor.

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