KR102404691B1 - Fuel gas treating system in ships - Google Patents

Abstract

A fuel gas management system for a ship is disclosed. In the fuel gas management system of a ship according to this embodiment, a storage tank for accommodating liquefied gas and boil-off gas, a first compressor for pressurizing boil-off gas of the storage tank is provided, and means for consuming the boil-off gas pressurized by the first compressor A boil-off gas supply line supplied to the The line includes a heat exchanger for exchanging a portion of the pressurized BOG with BOG at the front end of the first compressor on the BOG supply line, and a first gas-liquid separator for receiving BOG cooled by the heat exchanger but separating it into a gas component and a liquid component; , a gas component circulation line for depressurizing the gas component of the first gas-liquid separator via an expander, and a second gas-liquid separator for receiving the decompressed gas component supplied by the gas component circulation line but separating it into a gas component and a liquid component; A liquid component circulation line for supplying the liquid component of the first gas-liquid separator to the second gas-liquid separator; It may be provided, including a gas component recovery line for supplying to the front end of the first compressor on the line, and a liquid component recovery line for supplying the liquid component of the second gas-liquid separator to the storage tank.

Description

Ship's fuel gas management system {FUEL GAS TREATING SYSTEM IN SHIPS }

The present invention relates to a fuel gas management system for a ship, and more particularly, to a fuel gas management system for a ship that can promote efficient use and management of fuel gas.

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.

For ease of storage and transportation, natural gas is usually reduced to 1/600 in volume by cooling natural gas to about -162 degrees Celsius. It has changed and is being managed and operated.

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 completely insulate and accommodate 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 in 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 intends to provide a fuel gas management system for a ship capable of efficiently using and managing fuel gas.

This embodiment is intended to provide a fuel gas management system for a ship that can promote efficient facility operation with a simple structure.

This embodiment intends to provide a fuel gas management system for a ship capable of improving energy efficiency.

This embodiment intends to provide a fuel gas management system for a ship capable of stably performing a reliquefaction process of boil-off gas.

This embodiment intends to provide a fuel gas management system for a ship that can improve structural stability of facilities through effective re-liquefaction and treatment of BOG.

According to one aspect of the present invention, a storage tank for accommodating liquefied gas and boil-off gas, a first compressor for pressurizing boil-off gas of the storage tank is provided, and the boil-off gas pressurized by the first compressor is supplied to a consumption means a boil-off gas supply line, a reliquefaction line for receiving and re-liquefying a portion of the boil-off gas pressurized by the first compressor, and a compander having the first compressor and an expander for decompressing the boil-off gas; The liquefaction line includes a heat exchanger for exchanging a portion of the pressurized BOG with BOG at the front end of the first compressor on the BOG supply line, and a second heat exchanger that receives BOG cooled by the heat exchanger but separates it into a gas component and a liquid component 1 gas-liquid separator, a gas component circulation line for depressurizing the gas component of the first gas-liquid separator via the expander, and a gas component supplied by the gas component circulation line, but separated into a gas component and a liquid component a second gas-liquid separator, a liquid component circulation line for supplying the liquid component of the first gas-liquid separator to the second gas-liquid separator, and a pressure reducing valve provided in the liquid component circulation line to depressurize the liquid component; A gas component recovery line for supplying the gas component of the separator to the front end of the first compressor on the storage tank or the boil-off gas supply line, and a liquid component recovery line for supplying the liquid component of the second gas-liquid separator to the storage tank can be provided.

The reliquefaction line further includes a first pressure sensor provided at the front end of the pressure reducing valve on the liquid component circulation line to measure a pressure, and the pressure reducing valve performs an opening and closing operation based on the pressure information measured by the first pressure sensor. can be controlled.

The reliquefaction line includes a second pressure sensor for measuring the internal pressure of the first gas-liquid separator, and a first provided in the gas component circulation line, the opening and closing operation of which is controlled based on the pressure information measured by the second pressure sensor It may be provided by further comprising a valve.

The reliquefaction line is provided with a level sensor for measuring the water level of the first gas-liquid separator, and a front end of the first pressure sensor on the liquid component circulation line, the opening and closing operation is controlled based on the pressure information measured by the level sensor It may be provided by further comprising a second valve.

The gas component circulation line and the liquid component circulation line merge and are connected to the second gas-liquid separator, and the reliquefaction line is provided in front of the point where the liquid component circulation line on the gas component circulation line joins the counter flow of the gas flow. It may be provided by further comprising a check valve to prevent.

The compander may further include a second compressor provided at a rear end of the first compressor to additionally pressurize the boil-off gas introduced into the reliquefaction line.

It may further include an emergency drive line that operates when the compander is stopped, and the emergency drive line may include a preliminary compressor for pressurizing the boil-off gas in the storage tank.

The first compressor may pressurize the boil-off gas to about 12 to 17 bar, and the second compressor may pressurize the boil-off gas pressurized by the first compressor to about 40 to 60 bar.

The expander may reduce the pressurized boil-off gas to about 4 bar.

The fuel gas management system of the ship according to this embodiment has the effect of efficiently using and managing fuel gas.

The fuel gas management system of the ship according to this embodiment has the effect of improving energy efficiency.

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

The fuel gas management system of the ship according to this embodiment has the effect of improving the structural stability of the facility.

The fuel gas management system of the ship according to this embodiment has the effect of stably performing the re-liquefaction process of boil-off gas.

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

Referring to FIG. 1 , in the fuel gas management system 100 of a ship according to an embodiment of the present invention, a storage tank 110 , a first compressor 121 for pressurizing boil-off gas of the storage tank 110 is provided, and the second 1 A boil-off gas supply line 120 for supplying boil-off gas pressurized through the compressor 121 to a consumption means, a first compressor 121 and a second compressor 122 for pressurizing boil-off gas, and pressure reduction of boil-off gas The compander 130 having the expander 144, the reliquefaction line 140 that receives a part of the pressurized BOG and reliquefies it, operates when the operation of the compander 130 is stopped due to a malfunction or maintenance. It may be provided to include an emergency drive line 160 .

In the following embodiments, as an example for better understanding of the present invention, liquefied natural gas and boil-off gas generated therefrom have been applied, but the present invention is not limited thereto and various liquefied gases such as liquefied ethane gas and liquefied hydrocarbon gas and this It should be understood in the same way with the same technical idea even when the boil-off gas generated from the gas is applied.

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 or is reliquefied by the re-liquefaction line 140 as in this embodiment, and 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 consumption means may be supplied with fuel gas such as liquefied natural gas and boil-off gas accommodated in the storage tank 110 to generate propulsive force of the ship or to generate power for power generation such as internal facilities of the ship. The consuming means includes a first consuming means 11 for receiving a relatively high pressure fuel gas to generate an output, a second consuming means 12 for receiving a relatively low pressure fuel gas to generate an output, and surplus fuel gas. It may include a third defense means 13 made of a GCU (Gas Combustion Unit) for receiving and consuming. For example, the first consuming means 11 is made of an X-DF engine capable of generating output with fuel gas of relatively high pressure, and the second consuming means 12 generates output with fuel gas of relatively low pressure. It can be made of a DFDE engine, etc. However, the present invention is not limited thereto, and it should be understood that the same number of engines and various types of engines are used.

The boil-off gas supply line 120 may be provided to pressurize the boil-off gas existing in the storage tank 110 and supply it to the consumption means 11 , 12 , 13 and the reliquefaction line 140 . The boil-off gas supply line 120 is provided with an inlet end connected to the inside of the storage tank 110 , and an outlet end end may be branched and connected to the consumption means 11 , 12 , 13 , respectively. In particular, at the front end of the second consuming means 12 and the third consuming means 13 on the boil-off gas supply line 120 , the pressure of the pressurized boil-off gas is adjusted according to the required pressure level of each of the consumption means 12 and 13 . A pressure reducing valve (not shown) may be provided, respectively.

A plurality of first compressors 121 of the compander 130 are provided in the BOG supply line 120 to process BOG according to the conditions required by the engine, the first compressor 121 and the second At the rear end of the compressor 122 , a reliquefaction line 140 , which will be described later, may be provided branching from the boil-off gas supply line 120 .

The first compressor 121 provided in the compander 130 may be provided in a plurality of stages to compress the boil-off gas in stages. In addition, it may further include a cooler (not shown) for cooling the boil-off gas heated while being compressed by the compressor. The first compressor 121 may pressurize the boil-off gas to a pressure level corresponding to the required pressure value of the first consuming means 11 . As described above, when the first consuming means 11 is made of an X-DF engine, the first compressor 121 may pressurize the boil-off gas to a pressure level of about 12 to 17 bar.

In FIG. 1 , the first compressor 121 is illustrated as being composed of a three-stage compressor, but this is an example, and the first compressor 121 may be composed of a variable number of compressors and coolers depending on the required pressure condition and temperature of the consumption means. can In addition, a heat exchanger 142 of the reliquefaction line 140 to be described later may be installed at the front end of the first compressor 121 on the boil-off gas supply line 120 , and a detailed description thereof will be provided later.

The second compressor 122 is provided at the rear end of the first compressor 121 to additionally pressurize the boil-off gas flowing into the reliquefaction line 140 . Like the first compressor 121 , the second compressor 122 may be disposed in multiple stages to compress the boil-off gas in stages. The second compressor 122 may further include a cooler (not shown) for cooling the boil-off gas heated while being compressed. In FIG. 1 , the second compressor 122 is illustrated as being composed of a two-stage compressor, but this is an example, and the second compressor 122 may be composed of various number of compressors and coolers depending on the required pressure condition and temperature of the consumption means. can

The compander 130 includes a first compressor 121 and a second compressor 122 for pressurizing the supplied boil-off gas, and an expander 144 for decompressing the supplied boil-off gas, and the first compressor 121 ) may pressurize the boil-off gas by using the boil-off gas expansion force in the expander 144 . For example, the expander 144 is provided as a turbine type, and the expander 144 rotates the turbine with the expansion force obtained in the process of decompressing and expanding the boil-off gas, and energy generated by the rotation of the turbine By utilizing the first compressor 121 can pressurize the boil-off gas. The first compressor 121 of the compander 130 may pressurize the boil-off gas to a pressure level corresponding to the required pressure value of the first consumption means 11 . Specifically, the first compressor 121 may pressurize the introduced BOG to a pressure level of about 12 to 17 bar, and the second compressor 122 may pressurize the BOG introduced into the reliquefaction line 140 by about 40 It can be pressurized to a pressure level of up to 60 bar. In addition, the expander 144 may reduce the introduced boil-off gas to a pressure level of about 4 bar.

The re-liquefaction line 140 passes through the first compressor 121 and the second compressor 122 of the boil-off gas supply line 120 and is provided to receive and reliquefy the pressurized boil-off gas.

The reliquefaction line 140 includes a heat exchanger 142 that cools the pressurized BOG, and a first gas-liquid separator 143 that receives BOG cooled through the heat exchanger 142 and separates it into a gas component and a liquid component. ), a gas component circulation line 145 for supplying the gas component of the first gas-liquid separator 143 to the expander 144 of the compander 130 to reduce pressure, and a liquid component of the first gas-liquid separator 143 is supplied A liquid component circulation line 146 for receiving and depressurizing, a pressure reducing valve 146c for decompressing the liquid component supplied along the liquid component circulation line 146, a gas component circulation line 145 and a liquid component circulation line 146 along the A liquid component recovery line ( 148), the gas component recovery line 149 for supplying the gas component of the second gas-liquid separator 147 to the storage tank 110 or the boil-off gas supply line 120, and the liquid component circulation line 146 provided in the liquid The first pressure sensor 146b for measuring the component pressure, the second pressure sensor 143a for measuring the internal pressure of the first gas-liquid separator 143, and the level for measuring the water level of the first gas-liquid separator 143 A sensor 143b, a first valve 145a provided in the gas component circulation line 145 to control the flow rate of the gas component, and a second valve provided in the liquid component circulation line 146 to adjust the flow rate of the liquid component ( 146a).

The heat exchanger 142 is provided to cool the boil-off gas pressurized through the first compressor 121 and the second compressor 122 . The heat exchanger 142 transfers the pressurized boil-off gas along the boil-off gas supply line 120 to heat exchange with the boil-off gas before the pressurization of the front end of the first compressor 121, so that the first compressor 121 and the second compressor 122 ), while cooling the pressurized BOG, the BOG before the pressurization of the front end of the first compressor 121 may be heated. Since the pressurized BOG is pressurized by the first compressor 121 and the second compressor 122 to increase the temperature and pressure, the low temperature before passing through the first compressor 121 of the BOG supply line 120 is By exchanging heat with BOG, the high-temperature pressurized BOG supplied to the reliquefaction line 140 can be cooled. As described above, since the pressurized BOG can be cooled without a separate cooling device by the heat exchanger 142, unnecessary waste of power is prevented, the facility is simplified, and the efficiency of facility operation can be promoted.

The first gas-liquid separator 143 is provided to separate the boil-off gas in a gas-liquid mixed state cooled by passing through the heat exchanger 142 into a gas component and a liquid component. As the pressurized BOG is cooled while passing through the heat exchanger 142, some reliquefaction is performed, but an unliquefied gas component may also exist. Accordingly, the first gas-liquid separator 143 receives the boil-off gas cooled by passing through the heat exchanger 142, and separates it into a gas component and a liquid component to facilitate easy handling and management of each component. In particular, as will be described later, when a liquid component flows into the expander 144 of the compander 130, there is a risk of damage to the equipment. Stable operation of the expander 144 can be promoted by supplying only the post gas component to the gas component circulation line 145 to be described later.

The gas component circulation line 145 is provided to supply and pass through the gas component separated in the first gas-liquid separator 143 to the expander 144 of the compander 130 . To this end, the inlet side end of the gas component circulation line 145 communicates with the upper inner side of the first gas-liquid separator 143, and the outlet side end joins the liquid component circulation line 146 to be described later, and the second gas-liquid separator 147 ), but the middle portion may be provided to pass through the expander 144 of the compander 130 .

The expander 144 of the compander 130 is provided to depressurize and expand the gas component of the first gas-liquid separator 143 transferred along the gas component circulation line 145 . The expander 144 is pressurized through the first compressor 121 and the second compressor 122, and by decompressing the cooled boil-off gas through the heat exchanger 142, it is cooled and expanded to realize re-liquefaction of the gas component. have. The expander 144 may reduce the gas component to a pressure level corresponding to the internal pressure of the second gas-liquid separator 147 , specifically, a pressure level of about 4 bar.

On the other hand, the first gas-liquid separator 143 is provided with a second pressure sensor 143a for measuring the internal pressure, and the gas component circulation line 145 has a first valve 145a for controlling the supply amount of the gas component supplied along it. ) can be provided.

Whether to open and close the first valve 145a may be adjusted based on information on the internal pressure of the first gas-liquid separator 143 measured by the second pressure sensor 143a. For example, when the internal pressure of the first gas-liquid separator 143 measured by the second pressure sensor 143a is equal to or greater than a preset pressure level, the operation of the first valve 145a may be controlled in an opening direction, and vice versa. When the internal pressure of the first gas-liquid separator 143 measured by the second pressure sensor 143a is less than a preset pressure level, the operation of the first valve 145a may be controlled in a closing direction. The opening/closing operation of the first valve 145a may be automatically controlled by a controller (not shown), or the opening/closing operation may be manually controlled by an operator.

In addition, the gas component circulation line 145 is provided at the front end of the point where the liquid component circulation line 146 to be described later joins the counter flow of the gas flow, specifically, the gas from the liquid component circulation line 146 or the second gas-liquid separator 147 . A check valve 145b for preventing gas flow from occurring to the component circulation line 145 may be provided.

The liquid component circulation line 146 is provided to supply the liquid component that is reliquefied through the heat exchanger 142 and separated in the first gas-liquid separator 143 to a second gas-liquid separator 147 to be described later. To this end, the inlet side end of the liquid component circulation line 146 communicates with the inner lower side of the first gas-liquid separator 143 , and the outlet side end joins the gas component circulation line 145 to the second gas-liquid separator 147 . A second valve 146a for controlling the supply amount of the liquid component transferred along the liquid component circulation line 146, a first pressure sensor 146b for measuring the pressure of the liquid component, and a liquid component connected to the middle part A pressure reducing valve 146c for reducing the pressure may be sequentially provided.

The first gas-liquid separator 143 is provided with a level sensor 143b for measuring the level of the liquid component accommodated therein, and the second valve 146a is the first gas-liquid separator 143 measured by the level sensor 143b. Whether to open or close and the degree of opening and closing can be adjusted based on water level information. For example, when the water level of the first gas-liquid separator 143 measured by the level sensor 143b is higher than or equal to a preset water level, the operation of the second valve 146a may be controlled in an opening direction, and vice versa. When the measured water level of the first gas-liquid separator 143 is less than a preset water level level, the operation of the second valve 146a may be controlled in a closed direction. The opening/closing operation of the second valve 146a may be automatically controlled by a controller (not shown), or the opening/closing operation may be manually controlled by an operator.

The first pressure sensor 146b is provided at the rear end of the second valve 146a on the liquid component circulation line 146 to measure the pressure of the liquid component transferred along the liquid component circulation line 146 . In addition, the pressure reducing valve 146c may reduce the liquid component transferred along the liquid component circulation line 146 to a pressure level corresponding to the internal pressure of the second gas-liquid separator 147, specifically, to a pressure level of about 4 bar. .

Natural gas is a mixture containing ethane, propane, butane, nitrogen, etc. in addition to the main component methane. Of these, the boiling point of nitrogen is about -195.8 degrees Celsius, which is very low compared to other components such as methane (boiling point -161.5 degrees Celsius) and ethane (boiling point -89 degrees Celsius). As the nitrogen component has a very low boiling point, the reliquefaction efficiency of the boil-off gas varies according to the content of the nitrogen component. Typically, boil-off gas contains a nitrogen component of about 10 mole%, but when the concentration of the nitrogen component is lower than this, the liquid component separated in the first gas-liquid separator 143 increases, and thus the liquid component is reduced by the pressure reducing valve 146c. ), there is a fear that a large amount of flash gas may be generated in the process of decompression. This not only reduces the reliquefaction efficiency of the boil-off gas, but also has a problem in preventing the supply of the reliquefaction component through the liquid component circulation line 146 .

Accordingly, the first pressure sensor 146b measures the pressure of the liquid component transferred along the liquid component circulation line 146, and controls the operation of the pressure reducing valve 146c based on this, thereby generating flash gas according to a sudden pressure drop. Alternatively, a decrease in gas flow can be prevented. In particular, the pressure reducing valve 146c is controlled in conjunction with the second valve 146a on the liquid component circulation line 146 to prevent a reverse flow of the gas flow generated during the decompression process and achieve reliquefaction efficiency through stable pressure reduction. This lowering problem can be solved.

The second gas-liquid separator 147 receives the boil-off gas in a gas-liquid mixed state supplied from the gas component circulation line 145 and the liquid component circulation line 146 , but is provided to separate the gas component into a gas component and a liquid component. The second gas-liquid separator 147 receives the gas flow respectively transferred along the gas component circulation line 145 and the liquid component circulation line 146, but separates the gas component and the liquid component for easy handling and management of each component can promote

The liquid component recovery line 148 may connect the second gas-liquid separator 147 and the storage tank 110 to re-supply the liquid component separated by the second gas-liquid separator 147 to the storage tank 110 . The liquid component recovery line 148 may have an inlet-side end connected to an inner lower side of the second gas-liquid separator 147 , and an outlet-side end connected to the inside of the storage tank 110 .

The liquid component recovery line 148 may be provided with a flow control valve (not shown) for controlling the supply amount of the liquid component recovered to the storage tank 110 , and the flow control valve is located at the water level of the second gas-liquid separator 147 . Depending on the degree of opening and closing can be controlled.

The gas component recovery line 149 includes a second gas-liquid separator 147 and a storage tank ( 110) or the second gas-liquid separator 147 and the boil-off gas supply line 120 may be provided. In FIG. 1 , the gas component recovery line 149 is illustrated as resupplying the gas component of the second gas-liquid separator 147 to the front end of the first compressor 121 on the boil-off gas supply line 120 , but in addition to this, the second This includes all cases of re-supply from the gas-liquid separator 147 to the storage tank 110 or together with the boil-off gas supply line 120 and the storage tank 110 .

The gas component recovery line 149 may be provided with a flow control valve (not shown) for controlling the supply amount of the gas component recovered to the storage tank 110 or the boil-off gas supply line 120 , and the flow control valve is the second The degree of opening and closing may be controlled according to the internal pressure of the gas-liquid separator 147 .

On the other hand, even in the case of malfunction of the compander 130 or stoppage for maintenance, continuous operation of the consumption means 11 , 12 , 13 such as the engine may be required depending on the operating environment of the ship, in particular, When the operation of the first compressor 121 of the panda 130 is stopped, there is a fear that the internal pressure of the storage tank 110 may rise as the boil-off gas inside the storage tank 110 accumulates. As described above, since there is a risk of safety accidents such as deformation or explosion of the storage tank 110 as the internal pressure of the storage tank 110 rises, the boil-off gas in the storage tank 110 must be continuously removed and treated.

Accordingly, when the compander 130 malfunctions or is stopped for maintenance, an emergency driving line 160 for removing and processing boil-off gas in the storage tank 110 may be provided.

The emergency driving line 160 is branched from the front end of the first compressor 121 on the boil-off gas supply line 120 and may be provided to rejoin at the rear end of the first compressor 121, and is configured to auxiliaryly pressurize the boil-off gas. A preliminary compressor 161 may be included. Like the first compressor 121 , the preliminary compressor 161 may be provided in multiple stages to compress the BOG in stages, and may further include a cooler (not shown) for cooling the BOG heated while being compressed. In this way, since the boil-off gas of the storage tank 110 can be removed and treated in any operating situation by the emergency drive line 160 and the preliminary compressor 161 provided therein, it is unnecessary to promote the stability of facility operation and at the same time Energy efficiency can be improved by minimizing the boil-off gas that must be consumed.

100: fuel gas management system 110: storage tank
120: boil-off gas supply line 121: first compressor
122: second compressor 130: compander 140: re-liquefaction line
142: heat exchanger
143: first gas-liquid separator 144: expander
145: gas component circulation line 146: liquid component circulation line
147: second gas-liquid separator 148: liquid component recovery line
149: gas component recovery line 160: emergency drive line

Claims (9)

a storage tank for accommodating liquefied gas and boil-off gas;
a boil-off gas supply line provided with a first compressor for pressurizing the boil-off gas in the storage tank and supplying the boil-off gas pressurized by the first compressor to a consumption means;
a re-liquefaction line for receiving and re-liquefying a portion of the boil-off gas pressurized by the first compressor; and
a compander including the first compressor and an expander for decompressing the boil-off gas;
The reliquefaction line is
A heat exchanger for exchanging a portion of the pressurized BOG with BOG at the front end of the first compressor on the BOG supply line, and a first gas-liquid separator for receiving BOG cooled by the heat exchanger but separating it into a gas component and a liquid component and a gas component circulation line for depressurizing the gas component of the first gas-liquid separator via the expander; a gas-liquid separator; a liquid component circulation line for supplying the liquid component of the first gas-liquid separator to the second gas-liquid separator; and a pressure reducing valve provided in the liquid component circulation line to depressurize the liquid component; A vessel comprising a gas component recovery line for supplying components to the storage tank or the front end of the first compressor on the boil-off gas supply line, and a liquid component recovery line for supplying the liquid component of the second gas-liquid separator to the storage tank Fuel gas management system. According to claim 1,
The reliquefaction line is
Further comprising a first pressure sensor provided in front of the pressure reducing valve on the liquid component circulation line to measure the pressure,
The pressure reducing valve is a fuel gas management system for a vessel in which an opening/closing operation is controlled based on the pressure information measured by the first pressure sensor. 3. The method of claim 2,
The reliquefaction line is
Further comprising a second pressure sensor for measuring the internal pressure of the first gas-liquid separator, and a first valve provided in the gas component circulation line, the opening and closing operation of which is controlled based on the pressure information measured by the second pressure sensor A ship's fuel gas management system. 4. The method of claim 3,
The reliquefaction line is
A level sensor for measuring the water level of the first gas-liquid separator, and a second valve provided in front of the first pressure sensor on the liquid component circulation line, the second valve being controlled based on the pressure information measured by the level sensor, A ship's fuel gas management system, including. 5. The method of claim 4,
The gas component circulation line and the liquid component circulation line join and are connected to the second gas-liquid separator,
The reliquefaction line is
The fuel gas management system of a ship further comprising a check valve provided in front of a point where the liquid component circulation line on the gas component circulation line joins to prevent a reverse flow of the gas flow. 6. The method of claim 5,
The compander is
The fuel gas management system of a ship further comprising a second compressor provided at the rear end of the first compressor to additionally pressurize the boil-off gas introduced into the reliquefaction line. 7. The method of claim 6,
It further includes; an emergency drive line that operates when the compander is stopped.
The emergency driving line is a fuel gas management system for a ship including a preliminary compressor for pressurizing the boil-off gas of the storage tank. 7. The method of claim 6,
The first compressor
The boil-off gas is pressurized to 12 to 17 bar,
The second compressor
A fuel gas management system of a ship for pressurizing the boil-off gas pressurized by the first compressor to 40 to 60 bar. 9. The method of claim 8,
The expander is
A ship's fuel gas management system that reduces pressurized boil-off gas to 4 bar.

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