KR101644389B1 - Fuel gas supplying system in ships - Google Patents

Abstract

A fuel gas supply system is disclosed. The fuel gas supply system, according to an embodiment of the present invention, comprises: a storage tank which receives liquefied gas and boil-off gas therein; a boil-off gas supply line which has a compression part for compressing the boil-off gas stored in the storage tank; and a re-liquefaction line which selectively receives a part of the boil-off gas compressed through the compression part and a part of the boil-off gas partially compressed in the compression part according to the nitrogen content of the boil-off gas to re-liquefy the received boil-off gas. Therefore, the present invention improves the re-liquefaction efficiency of the boil-off gas.

Description

[0001] FUEL GAS SUPPLYING SYSTEM IN SHIPS [0002]

The present invention relates to a fuel gas supply system, and more particularly, to a fuel gas supply system for a ship capable of efficiently using and managing fuel gas.

As IMO regulations on the emission of greenhouse gases and various air pollutants are strengthened, shipbuilding and marine industries are replacing the use of conventional oil and diesel oil with natural gas, which is a clean energy source, In many cases.

Natural gas is typically a liquefied natural gas (Liquefied Natural Gas), a colorless transparent cryogenic liquid with a volume reduced to 1/600 by cooling the natural gas to about -162 degrees Celsius for ease of storage and transportation. Management and operation.

Such liquefied natural gas is contained in a storage tank installed in an insulated manner on the hull and stored and transported. However, since it is virtually impossible to completely contain the liquefied natural gas, the external heat is continuously transferred to the inside of the storage tank, and the evaporated gas generated by naturally vaporizing the liquefied natural gas is accumulated in the storage tank . It is necessary to treat and remove the evaporated gas since the evaporated gas may increase the internal pressure of the storage tank and cause deformation and damage of the storage tank.

Conventionally, evaporation gas is flowed into a vent mast provided on the upper side of a storage tank, or a method of burning evaporation gas by using a GCU (Gas Combustion Unit) has been used. However, this is not desirable from the viewpoint of energy efficiency. Therefore, a method of re-liquefying the evaporation gas by supplying the evaporation gas with the liquefied natural gas or the fuel gas to the engine of the ship respectively, or using the re- .

Natural gas, on the other hand, is a mixture containing not only methane but also ethane, propane, butane, nitrogen and the like. The nitrogen boiling point is about -195.8 degrees Celsius, which is much lower than that of methane (boiling point -161.5 degrees) and ethane (boiling point-89 degrees Celsius).

Because of this property, the re-liquefaction efficiency of the evaporation gas is changed according to the content of the nitrogen component contained in the evaporation gas, and the optimum pressure and temperature for re-liquefaction are also changed. Further, in the process of storing and transporting the liquefied natural gas in the storage tank of the ship, the content of the nitrogen component contained in the evaporated gas fluctuates from time to time, so that the nitrogen content of the evaporated gas can be easily changed, Efficiency and uniformity of the fuel gas, and a method for efficiently using and managing the fuel gas is required.

Korean Patent Publication No. 10-2010-0035223 (published on Apr. 05, 2010)

An embodiment of the present invention seeks to provide a fuel gas supply system capable of maintaining and improving the re-liquefaction efficiency of the evaporation gas.

An embodiment of the present invention seeks to provide a fuel gas supply system that can efficiently use and manage fuel gas.

An embodiment of the present invention is to provide a fuel gas supply system capable of efficiently performing a liquefaction process of evaporated gas in response to a change in the content of nitrogen components contained in the evaporated gas.

An embodiment of the present invention is to provide a fuel gas supply system capable of efficient facility operation.

An embodiment of the present invention is to provide a fuel gas supply system capable of improving energy efficiency.

According to one aspect of the present invention, there is provided an evaporation apparatus comprising: a storage tank for storing a liquefied gas and an evaporation gas; an evaporation gas supply line having a compression section for pressurizing the evaporation gas of the storage tank; And a re-liquefaction line for selectively re-liquefying a part of the pressurized evaporated gas or a part of the evaporated gas during the pressurization of the pressurized section.

Wherein the redistribution line includes a first introduction line which is branched from the rear end of the compression section and introduces a part of the pressurized evaporation gas but depressurizes the pressurized evaporation gas and a second introduction line branching from the compression section interruption, A second introduction line introducing a part of the first introduction line and the second introduction line and having an on-off valve; a cooling unit for cooling the evaporation gas supplied through the first introduction line or the second introduction line; And a gas-liquid separator which separates the vaporized gas passing through the inflator into a gas component and a liquid component in a vapor-liquid mixed state.

Wherein the expansion valve and the on-off valve are provided so that the opening and closing operation is controlled based on the nitrogen content information measured by the nitrogen content measuring unit. The nitrogen content measuring unit measures the nitrogen content of the evaporating gas.

Liquid separator; a liquefied gas recovery line for supplying the liquid component separated from the gas-liquid separator to the storage tank; and a gas-liquid separator for supplying the gas component separated from the gas-liquid separator to the upstream side of the compression unit on the storage tank or the evaporation gas supply line And an evaporated gas recovery line for recovering the evaporated gas.

The nitrogen content measuring unit may be provided with a flow rate sensing device for measuring a flow rate of a gas component supplied to the evaporation gas recovery line along the evaporation gas recovery line.

Wherein the engine includes a first engine and a second engine that receives a fuel gas at a lower pressure than that of the first engine to generate an output and is branched from a rear end of the compression section on the evaporation gas supply line, A first fuel gas supply line for supplying an evaporated gas to the first engine, and a second fuel gas supply line for supplying an evaporated gas, which is branched from the compressed portion intermediate portion on the evaporated gas supply line and partially pressurized by the compression unit, And a second fuel gas supply line for supplying the first fuel gas to the first fuel gas supply line.

The cooling section may be provided with a heat exchanger for heat-exchanging the evaporation gas supplied through the first introduction line or the second introduction line with the evaporation gas at the upstream side of the compression section.

The fuel gas supply system according to the embodiment of the present invention has the effect of maintaining and improving the re-liquefaction efficiency of the evaporated gas.

The fuel gas supply system according to the embodiment of the present invention has an effect of easily performing the liquefaction process of the evaporation gas corresponding to the change of the content of the nitrogen component contained in the evaporation gas.

The fuel gas supply system according to the embodiment of the present invention has the effect of efficiently utilizing and managing the fuel gas.

The fuel gas supply system according to the embodiment of the present invention has an effect of enabling efficient facility operation.

The fuel gas supply system according to the embodiment of the present invention has an effect of improving the energy efficiency.

1 is a conceptual diagram showing a fuel gas supply system according to an embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following embodiments are provided to fully convey the spirit of the present invention to a person having ordinary skill in the art to which the present invention belongs. The present invention is not limited to the embodiments shown herein but may be embodied in other forms. For the sake of clarity, the drawings are not drawn to scale, and the size of the elements may be slightly exaggerated to facilitate understanding.

1 is a conceptual diagram showing a fuel gas supply system 100 according to an embodiment of the present invention.

1, a fuel gas supply system 100 according to an embodiment of the present invention includes a storage tank 110, an evaporation gas supply line 120 having a compression unit 121 for pressurizing the evaporation gas of the storage tank 110, A portion of the evaporated gas that has passed through the compression unit 121 and is pressurized depending on the nitrogen content of the evaporated gas or a portion of the evaporated gas that is pressurized during the pressurization of the decompression unit 121 is selectively supplied to the re- A nitrogen content measuring unit 140 for measuring the nitrogen content of the evaporation gas, and a nitrogen content measuring unit 140 for measuring the nitrogen content of the evaporation gas. The evaporation gas is branched from the rear end of the compression unit 121 on the evaporation gas supply line 120, A first fuel gas supply line 150 for supplying a partially pressurized gas branched from the intermediate portion of the compression unit 121 on the evaporation gas supply line 120 to a second engine or a GCU (Gas Combustion Unit) A second fuel gas supply line (160) Can.

In the following examples, liquefied natural gas and evaporative gas generated therefrom are used as an example to help understand the present invention. However, the present invention is not limited thereto, and various liquefied gases such as liquefied ethane gas and liquefied hydrocarbon gas, The same technical idea should be understood in the same way.

The storage tank 110 is provided to receive or store the liquefied natural gas and the evaporative gas generated therefrom. The storage tank 110 may be provided with a membrane-type cargo hold that is heat-treated to minimize vaporization of liquefied natural gas due to external heat penetration. The storage tank 110 stores the liquefied natural gas and the evaporation gas in a stable manner until the liquefied natural gas is received from the production site of the natural gas, The power generation engine of the present invention can be used as a fuel gas.

Since the storage tank 110 is generally installed in a heat-treated state, it is practically difficult to shut off the intrusion of external heat completely. Therefore, there is an evaporative gas generated by naturally vaporizing the liquefied natural gas in the storage tank 110 do. Such evaporated gas raises the internal pressure of the storage tank 110, and there is a risk of deformation and explosion of the storage tank 110. Therefore, it is necessary to remove or treat the evaporated gas from the storage tank 110. [ The evaporated gas generated in the storage tank 110 is supplied to the first fuel gas supply line 150 or the second fuel gas supply line 160 through the evaporation gas supply line 120 as in the embodiment of the present invention Or may be re-liquefied by the refueling line 130 and re-supplied to the storage tank 110. In addition, although not shown in the drawing, the evaporation gas may be supplied or consumed by supplying a vent mast (not shown) provided at an upper portion of the storage tank 110.

The engine may be supplied with fuel gas such as liquefied natural gas and vaporized gas stored in the storage tank 110 to generate propulsive force of the ship or generate electric power for power generation such as internal equipment of the ship. The engine may include a first engine that generates an output by receiving a relatively high-pressure fuel gas, and a second engine that generates an output by receiving a relatively low-pressure fuel gas. For example, the first engine may be an ME-GI engine or an X-DF engine capable of generating an output with a relatively high-pressure fuel gas, and the second engine may include a DFDE An engine, or the like. However, the present invention is not limited thereto, and it should be equally understood that various numbers of engines and various kinds of engines are used.

The evaporation gas supply line 120 may be provided to pressurize the evaporation gas present in the storage tank 110 and supply it as fuel gas to the first engine or the second engine or to supply it to the refueling line 130. The evaporation gas supply line 120 has an inlet end connected to the inside of the storage tank 110 and an outlet end connected to the first fuel gas supply line 120 and the first introduction line 112 of the refueling line 130. [ The second fuel gas supply line 160 and the second introduction line 132 of the redistribution line 130 may be branched to the intermediate portion. The evaporation gas supply line 120 is provided with a compression section 121 having a plurality of stages of compressors 121a so that the evaporation gas can be processed according to the conditions required by the engine or the pressure suitable for re-liquefaction of the evaporation gas.

The compression unit 121 may include a compressor 121a for compressing the evaporated gas and a cooler 121b for cooling the heated evaporated gas while being compressed. In the case where the engine is composed of a plurality of engines having different pressure conditions, the second fuel gas supply line 160, which will be described later, branches from the intermediate portion of the compression portion 121 to supply the evaporated gas partially pressurized by the second engine or the GCU .

1, the compression unit 121 is composed of five compressors 121a and a cooler 121b. However, the compression unit 121 may have various numbers of compressors A compressor 121a and a cooler 121b. Further, a cooling unit 133 of the re-liquefaction line 130 may be installed on the upstream side of the compression unit 121 on the evaporation gas supply line 120, and a detailed description thereof will be given later.

The re-liquefaction line 130 may selectively supply either a part of the evaporated gas passed through the compression section 121 or a part of the evaporated gas during the pressurization of the compression section 121 depending on the nitrogen content of the evaporated gas And is supplied to resuspend the liquid.

The re-liquefaction line 130 includes a first introduction line 131 for introducing a part of the pressurized evaporative gas branched from the rear end of the compression section 121 on the evaporation gas supply line 120, The second introduction line 132 branched from the interruption of the portion 121 and introducing a part of the evaporation gas during the pressurization, the first introduction line 131 or the second introduction line 132 is cooled An expansion unit 134 for decompressing the evaporation gas that has passed through the cooling unit 133 and the cooling unit 133, a gas-liquid separator 135 for separating the vaporized gas passing through the inflator 134 into a gas component and a liquid component ), A liquefied gas recovery line 136 for re-supplying the liquid component separated in the gas-liquid separator 135 to the storage tank 110 and a gas component separated in the gas-liquid separator 135 from the storage tank 110 or the evaporation gas supply And an evaporation gas recovery line 137 for re-supply to the line 120 side.

Natural gas is a mixture containing ethane, propane, butane, nitrogen and the like in addition to the main component methane. Among them, the boiling point of nitrogen is about -195.8 degrees Celsius, which is much lower than that of methane (boiling point -161.5 degrees Celsius) and ethane (boiling point -89 degrees Celsius). Depending on the nature of the nitrogen component, the content of the nitrogen component contained in the evaporation gas also affects the re-liquefaction efficiency of the evaporation gas and the optimum pressure and temperature for re-liquefaction of the evaporation gas.

For example, when the nitrogen content of the evaporation gas is about 10%, the evaporation gas is pressurized to about 300 bar, and then the optimum temperature for re-liquefaction is about -100 ° C when the pressure is reduced to 150 bar, If the nitrogen content of the gas corresponds to about 5%, the optimum temperature for re-liquefaction is about -110 degrees Celsius, even if the pressure is reduced to about 100 bar without additional pressurization or depressurization of the evaporation gas. That is, when the content of the nitrogen component of the evaporation gas is lowered, the optimal temperature of the re-liquefaction can be adjusted to an appropriate level without additional pressurization and depressurization processes. However, the above examples are not intended to limit the present invention. For example, the numerical values may be variously changed according to the content of the nitrogen component of the evaporation gas, the degree of the pressure of the evaporation gas, It will be self-explanatory.

Accordingly, the re-liquefaction line 130 is branched from the rear end of the compressing section 121 and is connected to the compression section 121 so as to introduce the evaporation gas having a different degree of pressure depending on the content of the nitrogen component of the evaporation gas into the liquefaction process. A first introduction line 131 having an expansion valve 131a for introducing a part of the completely pressurized evaporated gas passing through it and introducing it by decompression and a part of the evaporated gas branching from the interruption of the compression part 121 The first introduction line 131 and the second introduction line 132 include a second introduction line 132 for introducing the nitrogen content of the evaporation gas measured by the nitrogen content measuring unit 140 The introduction can be selectively controlled.

The first introduction line 131 is provided so as to undergo further pressurization and depressurization of the evaporation gas when the content of the nitrogen component of the evaporation gas is greater than a predetermined level. The first introduction line 131 is branched from the rear end of the compression unit 121 so as to receive the pressurized evaporated gas passing through the compression unit 121, The expansion valve 131a may be provided so as to be introduced under reduced pressure. The expansion valve 131a decompresses and supplies the pressurized evaporated gas conveyed along the first introduction line 131 and controls the opening and closing of the pressurized evaporated gas through the first introduction line 131 The flow can be controlled. The first expansion valve 131a may be selectively opened and closed with the opening and closing valve 132a of the second introduction line 132 to be described later and may be connected to the nitrogen content information measured by the nitrogen content measuring unit 140 The opening and closing operation can be controlled based on this. The expansion valve 131a may consist of a Joule-Thomson valve but is not limited thereto and may include a single device having an expander and an on-off valve.

The second introduction line 132 is a line for directly introducing a part of the evaporation gas during the pressurization to the redistribution line 130 side without the additional pressurization and depressurization of the evaporation gas when the content of the nitrogen component of the evaporation gas is smaller than a predetermined level . To this end, the second introduction line 132 may include an open / close valve 132a that branches off from the stop of the compression unit 121 and controls whether the evaporation gas is supplied during the pressurization. The opening / closing valve 132a can regulate the flow of the evaporating gas during the pressurization, which is controlled by the operation to be opened or closed and is conveyed along the second introduction line 132. The opening and closing valve 132a may be selectively opened and closed with the expansion valve 131a of the first introduction line 131 and may be opened and closed based on the nitrogen content information measured by the nitrogen content measuring unit 140, Can be controlled.

1, the second introduction line 132 is shown branched from the rear end of the compressor 121a and the cooler 121b at the four stages of the compression section 121 including the five stages of compressors 121a , Which may be varied in various ways depending on the specifications of the respective compressors 121a and the degree of pressurization.

As described above, depending on the nitrogen component content of the evaporated gas, either a part of the evaporated gas pressurized by the first introduction line 131 or the second introduction line 132, or a part of the evaporated gas during the pressurization, By liquefying it, it is possible to improve the remelting efficiency and stabilize it. Especially, when the nitrogen component content of the evaporation gas is smaller than a predetermined level, unnecessary additional pressurization and depressurization steps may not be performed by directly introducing the evaporation gas during the pressurization by the second introduction line 132 and re- The efficiency of the liquefaction process can be improved. The load applied to the compressor provided at the rear end of the branch point of the second introduction line 132 can be reduced and the compressor capacity at the subsequent stage can be lowered.

The cooling section 133 is provided to cool the evaporation gas supplied through the first introduction line 131 or the second introduction line 133. [ The cooling unit 133 may be a heat exchanger for heat-exchanging the evaporated gas with the evaporated gas before the compressed unit 121 conveyed along the evaporated gas supply line 120. The evaporation gas introduced into the re-liquefaction line 130 is pressurized by the compressing unit 121 and the temperature and pressure are increased. Thereby cooling the pressurized or evaporated gas during pressurization. Since the cooling unit 133 is provided as a heat exchanger, it is possible to cool the pressurized evaporated gas even without using a separate cooling apparatus, so that unnecessary waste of the power source can be prevented and the facility can be simplified and the facility operation efficiency can be improved.

The inflator 134 may be provided at the rear end of the cooling unit 133. [ The inflator 134 can reduce the evaporated gas that has passed through the cooling unit 133 and reduce the pressure of the evaporated gas, so that the evaporated gas can be re-liquefied. The inflator 134 may reduce the pressurized evaporated gas to a pressure level corresponding to the internal pressure of the storage tank 110. The inflator 134 may, for example, be a Joule-Thomson valve as shown in FIG. 1, but is not limited thereto.

The gas-liquid separator 135 is cooled and decompressed while passing through the inflator 134 to receive the vaporized gas in the vapor-liquid mixed state, and to separate the liquid component and the gas component. When the evaporation gas passes through the expander 134, most of the re-liquidization is performed, but a flash gas is generated in the process of reducing the pressure, so that a gas component may be generated. The liquid component of the vaporized gas in the gas-liquid mixed state, which is sequentially passed through the cooling section 133 and the expander 134 and supplied to the gas-liquid separator 135, is supplied through the liquefied gas recovery line 136 to the storage tank 110 And the gas component may be supplied to the storage tank 110 or the evaporation gas supply line 120 by the evaporation gas recovery line 137 to be described later.

The liquefied gas recovery line 136 may be provided to connect the gas-liquid separator 135 and the storage tank so as to re-supply the liquid component separated by the gas-liquid separator 135 to the storage tank 110. The liquefied gas recovery line 136 may be provided with its inlet side end communicating with the lower side of the gas-liquid separator 135 and the outlet side end communicating with the inside of the storage tank 110. The liquefied gas recovery line 136 may be provided with an on-off valve (not shown) for regulating the supply amount of the re-liquefied evaporated gas recovered to the storage tank 110.

The evaporation gas recovery line 137 is connected to the gas-liquid separator 135 and the storage tank 110 or the gas-liquid separator 135 so as to supply the gas components separated by the gas-liquid separator 135 to the storage tank 110 or the evaporation gas supply line 120 May be provided between the separator 135 and the evaporation gas supply line 120. 1, an evaporation gas recovery line 137 is shown to re-supply the gas component in the gas-liquid separator 135 to the upstream side of the compression section 121 on the evaporation gas supply line 120. However, in addition to the gas-liquid separator 135 To the storage tank 110, or to the evaporation gas supply line 120 and the storage tank 110 together.

The nitrogen content measuring unit 140 is provided to measure the content of the nitrogen component of the evaporated gas. The nitrogen content measuring unit 140 measures the content of the nitrogen component contained in the evaporation gas circulating in the fuel gas supply system 100 and controls the amount of the nitrogen component contained in the expansion valve 131 of the first introduction line 131 of the re- Closing operation of the opening / closing valve 132a of the first introduction line 131a or the second introduction line 132 can be selectively controlled.

The nitrogen content measuring unit 140 may measure the nitrogen content of the evaporated gas in real time and transmit the nitrogen content information to a display unit (not shown) to inform the operator of the vessel of the nitrogen content. Closing operation of the expansion valve 131a of the line 131 or the opening and closing valve 132a of the second introduction line 132 can be manually performed. The nitrogen content measuring unit 140 sends the nitrogen content information to the control unit (not shown), and the control unit controls the expansion valve 131a or the second introduction line 132 Closing valve 132a of the valve body 132a.

On the other hand, when the pressurized or pressurized evaporated gas is decompressed through the expander 134 after cooling by the cooler 133, the gas component such as the flash gas separated by the gas-liquid separator 135 Nitrogen component with low boiling point is contained at high concentration. A gas component containing a nitrogen component at a high concentration flows into the evaporation gas recovery line 137 that supplies the gas component separated in the gas-liquid separator 135 to the storage tank 110 or the evaporation gas supply line 120, The supply amount of the gas component transferred along the evaporation gas recovery line 137 greatly affects the content of the nitrogen component of the evaporation gas.

The nitrogen content measuring unit 140 may include a flow rate sensing device for measuring the flow rate of the gas component transferred along the evaporative gas recovery line 137. The flow rate sensing device is provided in the evaporation gas recovery line 137 to measure the flow rate of the gas component transferred along the evaporation gas recovery line 137 and to provide the first introduction line 131 of the reflux line 130, Closing operation of the expansion valve 131a of the first introduction line 132 or the opening / closing valve 132a of the second introduction line 132 can be controlled.

1, the nitrogen content measuring unit 140 is shown as being provided on the evaporating gas recovery line 137, but the present invention is not limited thereto. The nitrogen content measuring unit 140 may include a nitrogen content measuring unit It may be made of means or apparatus for measuring the content of nitrogen component of the evaporating gas by various methods or principles, and it is clear that the installation position may also be installed in various positions.

The first fuel gas supply line 150 is provided to supply the pressurized evaporative gas through the compression unit 121 to the first engine as the fuel gas. The first fuel gas supply line 150 may be provided such that the inlet side end portion is branched from the rear end of the compression portion 121 on the evaporation gas supply line 120 and the outlet side end portion is connected to the first engine. A three-way valve (not shown) is provided at a branch point of the first introduction line 131a of the first fuel gas supply line 150 and the refueling line 130 at the outlet side end of the evaporation gas supply line 120, The supply of the pressurized evaporation gas to the first fuel gas supply line 150 or the first introduction line 131 and the supply amount thereof can be adjusted.

The second fuel gas supply line 160 is branched from the intermediate portion of the compression unit 121 of the evaporation gas supply line 120 and is provided to supply the partially pressurized evaporation gas to the second engine or the GCU. The second fuel gas supply line 160 may be provided such that the inlet side end portion is connected to the intermediate portion of the compression portion 121 and the outlet side end portion is branched so that one side is connected to the second engine and the other side is connected to the GCU .

Since the second engine generates the output by receiving the relatively low-pressure fuel gas, the second engine is branched from the intermediate portion of the compression unit 121 that compresses the evaporated gas, . When the supply amount of the partially pressurized evaporative gas supplied through the second fuel gas supply line 160 is larger than the supply amount of the fuel gas required by the second engine, the GCU supplies and consumes the surplus pressurized evaporative gas .

1, the second fuel gas supply line 160 is shown branched from the compressor 121a and the rear end of the cooler 121b on the second stage of the compression unit 121 on the evaporation gas supply line 120. However, The position can be changed variously according to the capacity and specification of the compressor.

The fuel gas supply system 100 according to an embodiment of the present invention having such a structure measures the content of nitrogen components contained in the evaporated gas through the nitrogen content measuring unit 140, The introduction of the re-liquefaction line 130 of the pressurized evaporation gas or the evaporation gas during the pressurization is selectively performed so that the optimum pressure and temperature can be easily realized, thereby improving the remelting efficiency and stabilizing effect of the evaporation gas I have.

In addition, when the nitrogen component content of the evaporation gas is lower than the predetermined level, the evaporation gas during the pressurization can be introduced to re-liquefy. Therefore, the capacity and specification of the compressor 121a of the compression section 121, It is possible to efficiently select and arrange them, thereby achieving efficiency of facility construction and operation, and reducing costs.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is clearly understood that the same is by way of illustration and example only and is not to be taken by way of limitation, You will understand. Accordingly, the true scope of the invention should be determined only by the appended claims.

100: fuel gas supply system 110: storage tank
120: evaporation gas supply line 121: compression section
130: Re-liquefaction line 131: First introduction line
131a: expansion valve 132: second introduction line
132a: opening / closing valve 133: cooling section
134: inflator 135: gas-liquid separator
136: Liquefied gas recovery line 137: Evaporative gas recovery line
140: nitrogen content measuring unit 150: first fuel gas supply line
160: Second fuel gas supply line

Claims (7)

A storage tank for storing the liquefied gas and the evaporated gas;
An evaporation gas supply line having a compression section for pressurizing the evaporation gas of the storage tank; And
And a re-liquefaction line for selectively supplying and re-liquefying any one of a part of the evaporated gas which has passed through the compressed section and a part of the evaporated gas during the pressurization of the stop of the compression section in accordance with the nitrogen content of the evaporated gas,
The re-liquefaction line
A first introduction line branching from a downstream end of the compression section and introducing a part of the pressurized evaporation gas and reducing the pressure thereof; and a second introduction line branching from the compression section interruption and introducing a part of the evaporation gas during the pressurization, A cooling unit for cooling the evaporation gas supplied through the first introduction line or the second introduction line; an expander for decompressing the evaporation gas that has passed through the cooling unit; And a gas-liquid separator for separating the vaporized gas in a vapor-liquid mixed state into a gas component and a liquid component. delete The method according to claim 1,
Further comprising a nitrogen content measuring unit for measuring a nitrogen content of the evaporating gas,
The expansion valve and the on-off valve
Wherein the opening / closing operation is controlled based on the nitrogen content information measured by the nitrogen content measuring unit. The method of claim 3,
The re-liquefaction line
Liquid separator; a liquefied gas recovery line for supplying the liquid component separated from the gas-liquid separator to the storage tank; and an evaporative gas recovery line for supplying the gas component separated from the gas-liquid separator to the upstream side of the compression unit on the storage tank or the evaporative gas supply line The fuel gas supply system further comprising: 5. The method of claim 4,
The nitrogen content measuring unit
And a flow sensing device provided in the evaporative gas recovery line for measuring a flow rate of a gas component transferred along the evaporative gas recovery line. The method according to claim 1,
A first fuel gas supply line branched from the rear end of the compression section on the evaporation gas supply line and passing through the compression section to supply pressurized gas to the first engine; And
And a second engine or GCU (Gas Combustion Unit (GCU)) for generating an output by supplying a low-pressure fuel gas, which is branched from the intermediate portion of the compression section on the evaporation gas supply line and partially pressurized by the compression section, And a second fuel gas supply line for supplying the fuel gas to the first fuel gas supply line. The method according to claim 1,
The cooling unit
And a heat exchanger for heat-exchanging the evaporation gas supplied through the first introduction line or the second introduction line with the evaporation gas at the upstream side of the compression section.

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