KR102198068B1 - A Treatment System of Liquefied Gas - Google Patents

Abstract

A liquefied gas treatment system according to an embodiment of the present invention includes a liquefied gas storage tank; And connected to the liquefied gas storage tank, wherein the boil-off gas generated in the liquefied gas storage tank is heat-exchanged with the liquefied gas stored in the liquefied gas storage tank through the inside from the outside of the liquefied gas storage tank to liquefy at least a portion. It characterized in that it comprises a fuel line.
In the liquefied gas treatment system according to the present invention, when the liquefied gas is not separately discharged, the boil-off gas generated inside the tank can be prevented from increasing by the boil-off gas generated and accumulated inside the tank. It is economical because it can be re-liquefied, so there is no need to use an expensive tank.

Description

A Treatment System of Liquefied Gas

The present invention relates to a liquefied gas treatment system.

According to recent technological developments, liquefied gases such as Liquefied Natural Gas and Liquefied Petroleum Gas have been widely used in place of gasoline or diesel.

Liquefied natural gas is liquefied by cooling methane obtained by refining natural gas collected from a gas field. It is a colorless and transparent liquid that contains almost no pollutants and has a high calorific value. Liquefied petroleum gas, on the other hand, is a fuel made into a liquid by compressing gas containing propane (C3H8) and butane (C4H10) as main components from oil fields together with oil at room temperature.

Liquefied petroleum gas, like liquefied natural gas, is colorless and odorless, and is widely used as fuel for home, business, industrial and automobiles. Such liquefied gas is stored in a liquefied gas storage tank installed on the ground or in a liquefied gas storage tank provided on a ship, which is a transportation means for sailing the ocean.The liquefied natural gas is liquefied in a volume of 1/600. The volume of liquefied petroleum gas is reduced to 1/260 of propane and 1/230 of butane by liquefaction, which has the advantage of high storage efficiency.

Such liquefied gas is supplied and used to various consumers. Recently, an LNG fuel supply method in which an engine is driven by using LNG as fuel in an LNG carrier carrying liquefied natural gas has been developed. The method used is also applied to other ships other than LNG carriers.

However, the temperature and pressure of the liquefied gas required by a consumer such as an engine may be different from the state of the liquefied gas stored in the liquefied gas storage tank. Therefore, in recent years, continuous research and development has been made on a technology that controls the temperature and pressure of the liquefied gas stored in a liquid state and supplies it to a customer.

In particular, the liquefied gas stored in the liquefied gas storage tank is not supplied to the liquefied gas consumer, but can be simply transported in a state stored in the liquefied gas carrier.The liquefied gas inside the liquefied gas storage tank is evaporated naturally and the boil-off gas is stored in the liquefied gas If it accumulates inside the tank, there is a concern that the internal pressure of the tank may increase, so the installation of an expensive tank that can withstand high pressure may increase the manufacturing cost of the ship.

(Prior Document 1) Domestic Registration Publication No. 10-1277965 (2013.06.17 announcement)

The present invention was created to improve the prior art, and an object of the present invention is to re-liquefy the boil-off gas generated inside the tank to prevent an increase in the internal pressure of the tank when the liquefied gas is not separately discharged. It is to provide a liquefied gas treatment system.

A liquefied gas treatment system according to an embodiment of the present invention includes a liquefied gas storage tank; And connected to the liquefied gas storage tank, wherein the boil-off gas generated in the liquefied gas storage tank is heat-exchanged with the liquefied gas stored in the liquefied gas storage tank through the inside from the outside of the liquefied gas storage tank to liquefy at least a portion. It characterized in that it comprises a fuel line.

Specifically, the fuel line may include a boil-off gas line discharged from the liquefied gas storage tank and connected to be introduced into the liquefied gas storage tank; And a heat exchange line connected to the boil-off gas line and passing through the liquefied gas storage tank.

Specifically, the heat exchange line is branched from the boil-off gas line and joined again.

Specifically, the heat exchange line is formed in a spiral shape such that a contact surface with the liquefied gas inside the liquefied gas storage tank is expanded.

Specifically, the heat exchange line is formed in a zigzag shape such that a contact surface with the liquefied gas inside the liquefied gas storage tank is expanded.

Specifically, a boil-off gas compressor provided on the boil-off gas line to pressurize boil-off gas discharged from the liquefied gas storage tank; And a re-liquefaction device for liquefying the boil-off gas discharged from the boil-off gas compressor.

Specifically, the boil-off gas line is extended toward the bottom surface of the liquefied gas storage tank, and includes a plurality of outlets.

Specifically, a boil-off gas compressor provided on the fuel line to pressurize boil-off gas discharged from the liquefied gas storage tank; And a gas-liquid separator for gas-liquid separating the gas and liquid boil-off gas that is pressurized and discharged from the boil-off gas compressor.

Specifically, the fuel line is connected to the liquefied gas storage tank, the boil-off gas compressor, and the gas-liquid separator, the diesel line passing through the inside of the liquefied gas storage tank between the boil-off gas compressor and the gas-liquid separator; A liquid recovery line for recovering liquid fuel from the gas-liquid separator to the liquefied gas storage tank; And a gas recovery line for recovering gaseous fuel from the gas-liquid separator to the liquefied gas storage tank, wherein the gas recovery line includes a branch line branched to join the diesel line upstream of the boil-off gas compressor. It features.

In the liquefied gas treatment system according to the present invention, when the liquefied gas is not separately discharged, the boil-off gas generated inside the tank can be prevented from increasing by the boil-off gas generated and accumulated inside the tank. It is economical because it can be re-liquefied, so there is no need to use expensive tanks.

In addition, according to the present invention, when the reliquefaction apparatus fails, the boil-off gas can be re-liquefied while passing through the boil-off gas line and the heat exchange line without driving the re-liquefaction device, so that an increase in the internal pressure of the tank can be reduced.

In addition, since the present invention simplifies the reliquefaction facility, the system scale can be simplified, so that the top-side process facility is simplified, and the sizing of flare and vent facilities can be reduced by controlling the amount of BOG generated.

1 is a view showing a liquefied gas treatment system according to an embodiment of the present invention.
2 is a view showing a first form of a heat exchange line of a liquefied gas treatment system according to an embodiment of the present invention.
3 is a view showing a second form of a heat exchange line of the liquefied gas treatment system according to an embodiment of the present invention.
4 is a view showing a liquefied gas treatment system according to another embodiment of the present invention.

Objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments associated with the accompanying drawings. In adding reference numerals to elements of each drawing in the present specification, it should be noted that, even though they are indicated on different drawings, only the same elements are to have the same number as possible. In addition, in describing the present invention, if it is determined that a detailed description of a related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view showing a liquefied gas treatment system according to an embodiment of the present invention, Figure 2 is a view showing a first form of a heat exchange line of the liquefied gas treatment system according to an embodiment of the present invention. 3 is a view showing a second form of a heat exchange line of the liquefied gas treatment system according to an embodiment of the present invention.

1 to 3, the liquefied gas treatment system 100 according to an embodiment of the present invention includes a liquefied gas storage tank 110, a boil-off gas line 120, a heat exchange line 130, and a boil-off gas. It includes a compressor 140 and a reliquefaction device 150.

The liquefied gas storage tank 110 may be provided on a hull having a double bottom structure, and may store liquid cargo to be supplied to a liquefied gas consumer (not shown).

Here, the liquid cargo may be a liquefied gas such as liquefied natural gas or liquefied petroleum gas. Hereinafter, in the present specification, the liquefied gas, which is a liquid cargo, may be used in the sense of encompassing all gaseous fuels generally stored in a liquid state, such as LNG or LPG, ethylene, ammonia, etc., and may not be in a liquid state by heating or pressurization. For convenience, it can be expressed as liquefied gas.

This can also be applied to boil-off gas. In addition, for convenience, LNG can be used to mean not only NG (Natural Gas) in liquid state, but also NG in supercritical state, etc., and evaporation gas can be used to mean not only gaseous evaporation gas but also liquefied evaporation gas. have.

The liquefied gas storage tank 110 should store liquid cargo in a liquid state, and at this time, the liquefied gas storage tank 110 may have a pressure tank shape. In addition, the liquefied gas storage tank 110 is provided with a vent line 111 for pressure control, and when the pressure inside the liquefied gas storage tank 110 rises rapidly, the vent line 111 is opened to discharge the boil-off gas. Pressure can be adjusted. At this time, a relief valve (not shown) is provided on the vent line 111 to adjust the opening degree of the vent line 111. Preferably, the opening of the vent line 111 is opened when the internal pressure of the tank increases rapidly, and the internal pressure control of a general tank can be achieved by liquefying the boil-off gas through the boil-off gas line 120 to be described later, This will be described later.

The liquefied gas storage tank 110 of this embodiment is a thin film type and may be formed of a membrane type that is integrated with the hull, and, unlike this, various shapes such as may be formed as an independent tank. When the liquefied gas storage tank 110 is formed of a membrane type, the liquefied gas storage tank 110 is provided inside the hull to form a structure protruding from the top of the deck.

In contrast, when the liquefied gas storage tank 110 is formed as a stand-alone type, it may have a structure supported inside the hull. When the liquefied gas storage tank 110 is formed as an independent cargo tank, in order to prevent the cargo tank from moving in the transverse and longitudinal directions due to the movement of the hull such as rolling and pitching, the upper and lower parts of the cargo tank In the ship center line (ship center line) along the roll and roll prevention structure may be formed.

For example, the liquefied gas storage tank 110 may include an outer tank tank (not shown), an inner tank tank (not shown), and an insulation unit (not shown), and the stored liquefied gas is stored in a liquefied gas storage tank ( A manhole structure (not shown) may be provided in the upper portion of the liquefied gas storage tank 110 so as to be discharged toward the upper portion of the 110).

The outer tank of the liquefied gas storage tank 110 is a structure forming the outer wall of the liquefied gas storage tank 110, and may be formed of a steel material, and may have various shapes such as a polygonal cross section.

The inner tank tank is provided inside the outer tank tank, and may be supported and installed inside the outer tank tank by a support (not shown). At this time, the support may be provided at the lower end of the inner tank, and of course, may be provided on the side of the inner tank to suppress the left and right flow of the inner tank.

The inner tank tank may be formed of a stainless material, and may be designed to withstand a pressure of 1 bar to 10 bar (for example, 6 bar). The reason why the inner tank tank is designed to withstand a certain pressure as described above is because the internal pressure of the inner tank tank may increase as the LNG provided in the inner tank tank is evaporated to generate boil-off gas.

The heat insulation part is provided between the inner tank and the outer tank and may block the transfer of external heat energy to the inner tank. At this time, the heat insulation may be in various forms such as a vacuum state.

Here, a chamfer (not shown) is formed at each corner of the liquefied gas storage tank 110, and a ballast tank (not shown) is provided in a chamfer (not shown) provided in the lower part. The ballast of the hull can be adjusted by the inflow and outflow of (using seawater as an example).

The liquefied gas storage tank 110 may be provided on a liquefied gas carrier (not shown), and the liquefied gas carrier is a ballast for efficient operation, balance maintenance, and stability of the propeller and rudder in water when there is insufficient cargo. The tank can be operated with ballast water such as seawater, and the water loaded in the ballast tank is generally called ballast water. The ballast tank may be provided on the left and right circumferential surfaces of the hull in addition to the chamfer formed under the liquefied gas storage tank.

In addition, a pump tower (not shown) for discharging liquid cargo may be provided inside the liquefied gas storage tank 110. The pump tower can pressurize the liquid cargo inside the liquefied gas storage tank and discharge it to the outside. In this case, the liquefied gas discharged to the outside of the liquefied gas storage tank 110 may be supplied to a liquefied gas consumer (not shown).

The liquefied gas consumer receiving the liquefied gas from the liquefied gas storage tank 110 may be driven through the boil-off gas and flash gas supplied from the liquefied gas storage tank 110 to generate power. At this time, the demand for liquefied gas is a high-pressure engine, and may be a gaseous fuel engine (for example, MEGI).

The liquefied gas consumer is a shaft connected to the crankshaft as the piston (not shown) inside the cylinder (not shown) reciprocates due to the combustion of the liquefied gas, and the crankshaft (not shown) connected to the piston is rotated. (Not shown) can be rotated. Therefore, when the liquefied gas consumer is driven, as the propeller (not shown) connected to the shaft rotates, the hull may move forward or backward.

Of course, in this embodiment, the liquefied gas consumer may be an engine for driving a propeller, but may be an engine for power generation or an engine for generating other power. That is, the present embodiment does not specifically limit the types of liquefied gas demanders. However, the demand for liquefied gas may be an internal combustion engine that generates driving power by combustion of boil-off gas and flash gas.

Alternatively, the demand for liquefied gas may be a dual fuel engine in which boil-off gas or oil is selectively supplied without boil-off gas and oil being mixed and supplied. The dual fuel engine selectively receives boil-off gas or oil in this way is to block the mixing and supply of two materials having different combustion temperatures, thereby preventing the efficiency of the liquefied gas consumer from deteriorating.

In this embodiment, a general technique of supplying liquefied gas from the liquefied gas storage tank 110 to a liquefied gas consumer may be applied, and a detailed description thereof will be omitted since it is replaced with a known technique. In addition to the supply of liquefied gas from the liquefied gas storage tank 110 to the liquefied gas consumer, the boil-off gas generated in the liquefied gas storage tank 110 of the present embodiment is recovered to the liquefied gas storage tank 110 and is recovered. Reliquefaction takes place in

In particular, the liquefied gas stored in the liquefied gas storage tank 110 of the present embodiment may not be supplied to a liquefied gas consumer, but may be simply transported in a state stored in a liquefied gas carrier. At this time, the liquefied gas inside the liquefied gas storage tank 110 evaporates naturally, so that the boil-off gas accumulates in the liquefied gas storage tank 110 and thus the internal pressure of the tank may increase.

In preparation for the case where liquefied gas is supplied to a liquefied gas consumer, if there is no discharge path, an expensive tank should be used for a stable structure of the liquefied gas storage tank 110 due to an increase in internal pressure of the tank. The internal pressure of the tank can be prevented from increasing by re-liquefying the boil-off gas through the configuration of the line 120 and the heat exchange line 130. Here, the boil-off gas line 120 and the heat exchange line 130 are configured to allow fuel to pass as a fuel line.

In addition, when liquefied gas stored in a separate liquefied gas storage tank (not shown) is used as fuel, the liquefied gas is moved from the liquefied gas storage tank 110 to a separate liquefied gas storage tank in consideration of the operation logic. So that the liquefied gas can be redistributed.

Specifically, the boil-off gas line 120 is a line through which boil-off gas is recovered, and is connected so that the boil-off gas is discharged from the liquefied gas storage tank 110 and flows into the liquefied gas storage tank 110. That is, the outlet through which the boil-off gas is discharged from the liquefied gas storage tank 110 is formed as one end of the boil-off gas line 120, and the inlet through which the discharged boil-off gas is recovered and introduced into the liquefied gas storage tank 110 is the boil-off gas. It consists of the other end of the line 120.

Here, the boil-off gas line 120 is formed to extend toward the bottom of the liquefied gas storage tank 110 and may include a plurality of ejection ports 121. The plurality of ejection ports 121 are provided to be immersed in the liquefied gas stored in the liquefied gas storage tank 110, so that the recovered boil-off gas is mixed with the liquefied gas, so that the boiled gas may be partially liquefied by the liquefied gas.

In addition, the boil-off gas line 120 is provided with a plurality of valves 120B, and the discharge amount of the boil-off gas can be adjusted according to the opening degree of the valve 120B. At this time, the valve 120B reduces the flow rate of the boil-off gas flowing to the re-liquefaction device 150 so that the boil-off gas is re-liquefied without driving the re-liquefaction device 150 when the re-liquefaction device 150 to be described later fails. As the flow rate of the boil-off gas passing through the line 130 is increased, the flow rate of the boil-off gas can be adjusted as necessary.

The boil-off gas compressor 140 is provided on the boil-off gas line 120, and the boil-off gas compressor 140 pressurizes the boil-off gas discharged from the liquefied gas storage tank 110. Here, the boil-off gas compressor 140 pressurizes the boil-off gas for ease of re-liquefaction of the boil-off gas, not to supply boil-off gas to the liquefied gas consumer, so the state of the boil-off gas to be pressurized must be It does not have to be tailored to the conditions demanded by the customer.

In addition, on the boil-off gas line 120, a re-liquefaction device 150 may be provided downstream of the boil-off gas compressor 140, and the re-liquefaction device 150 liquefies the boil-off gas discharged from the boil-off gas compressor 140. Let it.

The heat exchange line 130 is a configuration configured to facilitate re-liquefaction of the boil-off gas by exchanging the boil-off gas and the liquefied gas without directly mixing the boil-off gas and the liquefied gas, and is connected to the boil-off gas line 120, the liquefied gas storage tank ( 110).

The heat exchange line 130 is branched from the boil-off gas line 120 but joined again. For example, the heat exchange line 130 may be branched downstream of the boil-off gas compressor 140, and is preferably branched between the boil-off gas compressor 140 and the reliquefaction device 150, and the liquefied gas storage tank 110 ) Pass through the liquefied gas storage tank 110 so as to heat exchange with the liquefied gas inside.

The boil-off gas heat-exchanged with the liquefied gas via the liquefied gas storage tank 110 is recovered to the liquefied gas storage tank 110, and for this purpose, the heat exchange line 130 is joined to the boil-off gas line 120. As an example, the heat exchange line 130 may be joined downstream of the reliquefaction device 150 and mixed with the boil-off gas reliquefied in the reliquefaction device 150 to be recovered to the liquefied gas storage tank 110.

Here, in the heat exchange line 130, the boil-off gas flowing through the heat-exchange line 130 is not mixed with the liquefied gas inside the liquefied gas storage tank 110, and the boil-off gas inside the heat exchange line 130 is from the liquefied gas through the heat exchange line. Heat exchange is achieved by receiving low temperature. To this end, the heat exchange line 130 passes through the liquefied gas storage tank 110 and passes through the inside of the liquefied gas storage tank 110 and then exits.

In addition, as shown in FIGS. 2 and 3, the heat exchange line 130 is a line 131 modified inside the liquefied gas storage tank 110 so that the contact surface with the liquefied gas inside the liquefied gas storage tank 110 is expanded. , 131A, 131B) can be achieved.

That is, as shown in FIG. 2, the deformed line 131A may have a spiral formed from top to bottom. As another example, as shown in FIG. 3, the deformed line 131B may have a zigzag shape, and the zigzag shape may form a curve as shown in the drawing, but various modifications are possible, such as being bent at a right angle.

As described above, this embodiment is to prevent an increase in the internal pressure of the tank by the evaporation gas generated and accumulated inside the liquefied gas storage tank 110 when the liquefied gas is not separately discharged, the liquefied gas storage tank (110) It is economical because there is no need to use expensive tanks as it can re-liquefy the boil-off gas generated inside.

In addition, when the reliquefaction device 150 fails, the boil-off gas may be reliquefied while passing through the boil-off gas line 120 and the heat exchange line 130 without driving the re-liquefaction device 150, so that the internal pressure of the tank is reduced. You can reduce the rise.

4 is a view showing a liquefied gas treatment system according to another embodiment of the present invention. Components that are the same as or corresponding to the above-described embodiment are given the same reference numbers, and redundant descriptions thereof will be omitted.

4, the liquefied gas treatment system 100 according to another embodiment of the present invention includes a liquefied gas storage tank 110, a diesel oil line 230, a liquid recovery line 220, and a gas recovery line 221. ), a boil-off gas compressor 140 and a gas-liquid separator 250.

The gas-liquid separator 250 is capable of gas-liquid separation of gas and liquid boil-off gas, and the gas-liquid separator 250 is provided on the diesel line 230 and downstream of the boil-off gas compressor 140, on the diesel line 230 By separating the fuel pressurized and discharged from the provided boil-off gas compressor 140 into gas and liquid, the amount of fuel in the gaseous state can be reduced by re-liquefying the unliquefied fuel through a circulation process. This is because the vaporized gas in a gaseous state that is not liquefied can be discharged from the gas-liquid separator 250 to be liquefied through the vaporized gas compressor 140 and the diesel line 230.

The diesel line 230, the liquid recovery line 220, and the gas recovery line 221 of the present embodiment are fuel lines, and may circulate fuel in the liquefied gas storage tank 110.

First, the diesel line 230 is connected to the liquefied gas storage tank 110, the boil-off gas compressor 140, and the gas-liquid separator 250 so that the boil-off gas generated in the liquefied gas storage tank 110 is converted to the boil-off gas compressor 140. It is pressurized through and the liquefaction is easily achieved, and liquefaction is achieved by heat exchange with the cryogenic fuel via the inside of the liquefied gas storage tank 110. Here, the gas oil line 230 facilitates liquefaction through the inside of the liquefied gas storage tank 110 between the boil-off gas compressor 140 and the gas-liquid separator 250.

In particular, the diesel line 230 is a line modified inside the liquefied gas storage tank 110 so that the contact surface with the liquefied gas inside the liquefied gas storage tank 110 is expanded in the same or similar to the heat exchange line 130 of one embodiment. (131) can be achieved.

The fuel passing through the diesel line 230 includes the form of the liquefied fuel and the vaporized gas remaining as gas while passing through the modified line 131, and the gas-liquid separator 250 for additional reliquefaction of the vaporized gas. ) To the liquid recovery line 220 and the gas recovery line 221 are connected.

The liquid recovery line 220 may recover liquid fuel from the gas-liquid separator 250 to the liquefied gas storage tank 110. That is, the liquid recovery line 220 allows the liquefied fuel to be returned to and stored in the liquefied gas storage tank 110. The liquid recovery line 220 is connected from the gas-liquid separator 250 to the liquefied gas storage tank 110, and includes a plurality of ejection ports 121 in the same or similar to the boil-off gas line 120 of one embodiment, It may be provided to be immersed in the liquefied gas stored in the liquefied gas storage tank 110.

The gas recovery line 221 may recover gaseous fuel from the gas-liquid separator 250 to the liquefied gas storage tank 110. Here, the gas recovery line 221 is connected (221B) from the gas-liquid separator 250 to the liquefied gas storage tank 110, and may include a branch line 221A.

The gas recovery line 221B connected to the liquefied gas storage tank 110 is for controlling the amount of boil-off gas returned to the liquefied gas storage tank 110, and is a gaseous boil-off gas to the liquefied gas storage tank 110. It is possible to adjust the internal pressure of the liquefied gas storage tank 110 by reducing the decrease in the internal pressure by returning. Accordingly, the boil-off gas can be discharged to the diesel line 230 through internal pressure control without a separate pump. Here, of course, a valve (not shown) is provided on the gas recovery line 221B.

In addition, the branch line (221A) is discharged from the gas-liquid separator 250, so that the vaporized gas discharged from the gas-liquid separator 250 is directly returned to the liquefied gas storage tank 110 to further liquefy the unliquefied vaporized gas. It can be joined upstream of the boil-off gas compressor 140 without needing to be. The branch line 221A is made to be branched so as to join the diesel line 230 upstream of the boil-off gas compressor 140.

Here, reference numeral 10, which is not described, is a line supplied to the liquefied gas storage tank 110 and is joined to the liquid recovery line 220 to supply fuel to the liquefied gas storage tank 110. In addition, a filter (not shown) is provided downstream of the boil-off gas compressor 140 on the diesel line 230 to prevent the transfer of foreign substances.

As described above, this embodiment is to prevent an increase in the internal pressure of the tank by the evaporation gas generated and accumulated inside the liquefied gas storage tank 110 when the liquefied gas is not separately discharged, the liquefied gas storage tank (110) It is economical because there is no need to use expensive tanks as it can re-liquefy the boil-off gas generated inside.

In addition, since the system scale can be simplified by simplifying the reliquefaction facility, not only the top-side process facility can be simplified, but also the sizing of flare and vent facilities can be reduced by controlling the amount of BOG generated.

Although the present invention has been described in detail through specific examples, this is for explaining the present invention in detail, and the present invention is not limited thereto, and within the technical scope of the present invention, those of ordinary skill in the art It would be clear that the transformation or improvement is possible.

All simple modifications to changes of the present invention belong to the scope of the present invention, and the specific scope of protection of the present invention will be made clear by the appended claims.

100: liquefied gas treatment system 110: liquefied gas storage tank
111: vent line 120: boil-off gas line
120B: valve 121: spout
130: heat exchange line 140: boil-off gas compressor
150: reliquefaction device 220: liquid recovery line
221: gas recovery line 221A: branch line
230: diesel line 250: gas-liquid separator

Claims (9)

Liquefied gas storage tank; And
A fuel connected to the liquefied gas storage tank, wherein the boil-off gas generated in the liquefied gas storage tank is heat-exchanged with the liquefied gas stored in the liquefied gas storage tank through the inside from the outside of the liquefied gas storage tank to liquefy at least a portion Contains lines,
The fuel line,
After passing through the liquefied gas storage tank from the outside to the inside and passing through the inside of the liquefied gas storage tank, it is provided to penetrate from the inside of the liquefied gas storage tank to the outside, and the boil-off gas is liquefied gas inside the liquefied gas storage tank Liquefied gas treatment system, characterized in that provided to heat exchange without mixing with. The method of claim 1, wherein the fuel line,
A boil-off gas line discharged from the liquefied gas storage tank and connected to be introduced into the liquefied gas storage tank; And
And a heat exchange line connected to the boil-off gas line and passing through the liquefied gas storage tank. The method of claim 2, wherein the heat exchange line,
Liquefied gas treatment system, characterized in that the branching from the boil-off gas line and joining again. The method of claim 2, wherein the heat exchange line,
A liquefied gas treatment system, characterized in that the liquefied gas treatment system is formed in a spiral shape such that a contact surface with the liquefied gas inside the liquefied gas storage tank is expanded. The method of claim 2, wherein the heat exchange line,
A liquefied gas treatment system, characterized in that the liquefied gas treatment system is formed in a zigzag shape such that a contact surface with the liquefied gas inside the liquefied gas storage tank is expanded. The method of claim 2,
A boil-off gas compressor provided on the boil-off gas line to pressurize boil-off gas discharged from the liquefied gas storage tank; And
Liquefied gas processing system, characterized in that it further comprises a re-liquefaction device for liquefying the boil-off gas discharged from the boil-off gas compressor. The method of claim 2, wherein the boil-off gas line,
The liquefied gas treatment system, characterized in that it extends toward the bottom of the liquefied gas storage tank, and includes a plurality of jets. The method of claim 1,
A boil-off gas compressor provided on the fuel line to pressurize boil-off gas discharged from the liquefied gas storage tank; And
And a gas-liquid separator for separating gas and liquid boil-off gas from the boil-off gas compressor pressurized and discharged. The method of claim 8,
The fuel line,
A gas oil line connected to the liquefied gas storage tank, the boil-off gas compressor, and the gas-liquid separator, and passing through the interior of the liquefied gas storage tank between the boil-off gas compressor and the gas-liquid separator;
A liquid recovery line for recovering liquid fuel from the gas-liquid separator to the liquefied gas storage tank; And
And a gas recovery line for recovering gaseous fuel from the gas-liquid separator to the liquefied gas storage tank,
The gas recovery line, characterized in that it comprises a branch line branched so as to join the diesel line upstream of the boil-off gas compressor.

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