KR20160144737A - Vessel Including Storage Tanks - Google Patents

Abstract

A ship comprising a storage tank is disclosed.
The ship including the storage tank includes a first heat exchanger for cooling the natural gas supplied from the outside of the system by exchanging heat with the refrigerant; A first gas-liquid separator that passes through the first heat exchanger and separates heavy hydrocarbons from the cooled fluid; A first compander for compressing the fluid heat-exchanged as a refrigerant in the first heat exchanger or for expanding the fluid in which the heavy hydrocarbons are separated by the first gas-liquid separator; A first cooler for cooling the fluid compressed by the first compander; A distillation tower for separating the fluid passing through the first gas-liquid separator; A first valve for regulating the flow rate and pressure of the medium hydrocarbon sent from the first gas-liquid separator to the distillation column; A first compressor for compressing the fluid having passed through the first cooler after being compressed by the first compander; A second compander and a third compander for expanding or compressing the fluid; A second cooler for cooling the natural gas compressed by the first compressor; A second heat exchanger for cooling the natural gas by self-heat exchange; Expansion means for expanding the fluid that has passed through said second heat exchanger; A fourth cooler for cooling the fluid passing through the second compander; A fifth cooler for cooling the fluid passing through the third compander; And a second valve installed on the line for sending the evaporation gas in the storage tank to the second heat exchanger to regulate the flow rate and pressure of the evaporation gas sent from the storage tank to the second heat exchanger, The first heat exchanger is configured to cool the natural gas supplied from the outside of the system using the fluid discharged from the upper portion of the distillation tower as a refrigerant, and a part of the fluid cooled by the first cooler after being compressed by the first compander Pressure fuel supply system, and the second heat exchanger is branched after passing through the first compressor and the second cooler, and the second compander and the third com- pressor are branched from the front end of the first compressor, A fluid inflated by one or more of the pandas; And evaporation gas discharged from the storage tank as a refrigerant to cool a part of natural gas branched after passing through the first compressor and the second refrigerator.

Description

[0001] VESSEL Including Storage Tanks [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to a ship including a storage tank, and more particularly, to a ship including a storage tank, To a storage tank, comprising a storage tank.

Recently, the consumption of liquefied gas such as Liquefied Natural Gas (LNG) and Liquefied Petroleum Gas (LPG) has been rapidly increasing worldwide. The liquefied gas obtained by liquefying the gas at a low temperature has an advantage of being able to increase the storage and transport efficiency because the volume becomes very small as compared with the gas. In addition, liquefied natural gas (LNG) and other liquefied gases can be used as eco-friendly fuels that can reduce or eliminate air pollutants during the liquefaction process.

Liquefied natural gas is a colorless transparent liquid obtained by cooling methane-based natural gas to about -162 ° C and liquefying it, and has a volume of about 1/600 of that of natural gas. Therefore, it is very efficient when liquefied natural gas is transported to liquefied natural gas.

However, since the liquefaction temperature of natural gas is a cryogenic temperature of about -162 ° C at normal pressure, liquefied natural gas is easily vaporized due to temperature change sensitivity. However, since the external heat is continuously transferred to the storage tank, the liquefied natural gas is naturally vaporized continuously in the storage tank during the transportation of the liquefied natural gas, and the evaporation gas (BOG; Boil -Off Gas) occurs. This also applies to other low temperature liquefied gases such as ethane.

Evaporation gas is a kind of loss, and reducing the evaporation gas is an important issue in transportation efficiency. Further, when the evaporation gas accumulates in the storage tank, the internal pressure of the tank may rise excessively, and there is a risk that the tank may be damaged. Accordingly, various methods for treating the evaporative gas generated in the storage tank have been studied. Recently, a method of re-liquefying the evaporative gas and returning it to a storage tank, a method of using evaporative gas as an energy source of a fuel consuming place, Method and the like are used.

On the other hand, among the engines used in ships, there are DF (Dual Fuel) engine and ME-GI engine which can use natural gas as fuel.

The DF engine adopts the Otto Cycle, which consists of four strokes, and injects natural gas with a relatively low pressure of about 6.5 bar into the combustion air inlet and compresses the piston as it rises.

The ME-GI engine consists of two strokes and employs a diesel cycle in which high pressure natural gas at around 300 bar is injected directly into the combustion chamber at the top of the piston.

In recent years, there is a growing interest in ME-GI engines with better fuel efficiency and propulsion efficiency, but the demand for DF engines, which do not require the compression of natural gas used for fuel to high pressures, is also continuing.

In order to re-liquefy the evaporation gas, a separate liquefaction facility including a plurality of compressors and the like is required. However, the liquefaction facility of a compressor or the like requires a lot of cost and a lot of space in the ship.

In addition, when the amount of evaporation gas generated exceeds the amount required by the engine or the like, the evaporation gas is incinerated. Incineration of the evaporation gas is a waste of the energy and operation cost of the evaporation gas.

The present invention uses liquefied natural gas itself as a refrigerant without using a separate refrigerant system, liquefies natural gas and returns it to a storage tank, uses evaporative gas as a refrigerant to liquefy natural gas without a separate liquefaction facility , And to provide a vessel including a storage tank that associates a system for liquefying natural gas with a system for supplying fuel to the engine.

According to an aspect of the present invention, there is provided a ship including a storage tank, comprising: a first heat exchanger for cooling natural gas supplied from the outside of the system by exchanging heat with a refrigerant; A first gas-liquid separator that passes through the first heat exchanger and separates heavy hydrocarbons from the cooled fluid; A first compander for compressing the fluid heat-exchanged as a refrigerant in the first heat exchanger or for expanding the fluid in which the heavy hydrocarbons are separated by the first gas-liquid separator; A first cooler for cooling the fluid compressed by the first compander; A distillation tower for separating the fluid passing through the first gas-liquid separator; A first valve for regulating the flow rate and pressure of the medium hydrocarbon sent from the first gas-liquid separator to the distillation column; A first compressor for compressing the fluid having passed through the first cooler after being compressed by the first compander; A second compander and a third compander for expanding or compressing the fluid; A second cooler for cooling the natural gas compressed by the first compressor; A second heat exchanger for cooling the natural gas by self-heat exchange; Expansion means for expanding the fluid that has passed through said second heat exchanger; A fourth cooler for cooling the fluid passing through the second compander; A fifth cooler for cooling the fluid passing through the third compander; And a second valve installed on the line for sending the evaporation gas in the storage tank to the second heat exchanger to regulate the flow rate and pressure of the evaporation gas sent from the storage tank to the second heat exchanger, The first heat exchanger is configured to cool the natural gas supplied from the outside of the system using the fluid discharged from the upper portion of the distillation tower as a refrigerant, and a part of the fluid cooled by the first cooler after being compressed by the first compander Pressure fuel supply system, and the second heat exchanger is branched after passing through the first compressor and the second cooler, and the second compander and the third com- pressor are branched from the front end of the first compressor, A fluid inflated by one or more of the pandas; And a storage tank for cooling a part of the natural gas branched after passing through the first compressor and the second cooler by using the evaporation gas discharged from the storage tank as a refrigerant.

The natural gas supplied to the first heat exchanger may be natural gas that has undergone moisture drying in a dryer.

Heavy hydrocarbons separated from the first gas-liquid separator can be sent to the center of the distillation column, and the fluid expanded by the first compander can be sent to the top of the distillation column.

The first compander includes a first expansion unit for expanding the fluid sent from the first gas-liquid separator after the heavy hydrocarbons are separated by the first gas-liquid separator; And a first compression unit for compressing a fluid used as a refrigerant in the first heat exchanger, wherein the first compression unit and the first expansion unit are connected by an axis so that the first expansion unit The first compression section can compress the fluid by the energy obtained while expanding.

The distillation column is capable of separating the condensate from the fluid sent to the distillation column, and the vessel including the storage tank includes a sixth cooler for cooling the condensate discharged from the distillation column; And a third valve for controlling the flow rate and pressure of the condensate discharged from the distillation column.

The distillation tower may further include a reboiler at a lower portion thereof.

The vessel including the storage tank may further include a reboiler installed separately from the distillation tower.

A ship including the storage tank includes a second compressor for compressing natural gas having passed through the first compressor and the second cooler; And a third cooler for cooling the natural gas compressed by the second compressor, wherein the natural gas that has passed through the first compressor, the second cooler, the second compressor, and the third cooler Pressure fuel supply system.

The natural gas passing through the first compressor may be in a supercritical fluid state.

The second compander may include a second expanding portion for expanding the fluid and a second compressing portion for compressing the fluid, wherein the third compander includes a third expanding portion for expanding the fluid and a third expanding portion for compressing the fluid, 3 compressing portion, the second expanding portion is connected to the second compressing portion in an axial direction, the second expanding portion is capable of compressing the fluid by the energy obtained by expanding the fluid, and the third expanding portion The third expansion portion is capable of compressing the fluid by the energy obtained by expanding the fluid and the fluid inflated by at least one of the second expansion portion and the third expansion portion is , The pressure can be restored by at least one of the second compression unit and the third compression unit, and then sent back to the first compressor.

The expansion means may be an expansion valve or an expander.

Wherein the vessel including the storage tank further comprises: a third compressor for additionally compressing the natural gas compressed by the first compressor; A seventh cooler for lowering the temperature of the natural gas passing through the third compressor; A second gas-liquid separator provided at a downstream end of the expansion means for separating liquefied natural gas from natural gas in a gaseous state; A fourth valve for controlling the flow rate and pressure of the natural gas separated by the second gas-liquid separator; And a fifth valve for regulating the flow rate and pressure of the liquefied natural gas separated by the second gas-liquid separator and sent to the storage tank, wherein the first compressor, the second cooler, the third The natural gas having passed through the compressor and the seventh cooler can be cooled in the second heat exchanger and the gaseous natural gas separated by the second gas-liquid separator can be cooled by the second heat exchanger Can be sent on a line through which fluid is sent.

The natural gas passing through the first compressor and the third compressor may be in a supercritical fluid state.

Wherein the vessel including the storage tank further comprises: a third gas-liquid separator that passes through the second compander and separates part of liquefied natural gas and natural gas remaining in a gaseous state; And a sixth valve for controlling a flow rate and a pressure of the liquefied natural gas separated by the third gas-liquid separator and sent to the second heat exchanger, wherein the gas- Natural gas may be sent to the third compander, and the second heat exchanger may be a liquefied natural gas separated by the third gas-liquid separator and then passed through the sixth valve; And a fluid having passed through the third compander after being separated by the third gas-liquid separator may be used as a refrigerant.

The ship including the storage tank may further include a third heat exchanger for self-heat-exchanging liquefied natural gas passing through the second compander; A fourth compressor for compressing the fluid passing through the third heat exchanger; And an eighth cooler for lowering the temperature of the fluid that has passed through the fourth compressor, wherein the third heat exchanger uses the fluid sent from the second compander as a refrigerant, The fluid passing through the third heat exchanger, the fourth compressor, and the eighth cooler may be cooled and then sent to the third gas-liquid separator.

According to another aspect of the present invention, there is provided a method for separating natural gas from natural gas, the method comprising: a first heat exchanger for cooling natural gas supplied from the outside by heat exchange with a refrigerant; A first compressor of a first compander for expanding a fluid in which heavy hydrocarbons are separated by the first gas-liquid separator, a first compressor of a first compander compressing a fluid used as a refrigerant in the first heat exchanger, And a distillation column for separating the condensate from the medium hydrocarbon separated by the fluid expanded by the first expansion portion and the first gas-liquid separator, Distillation system; A first compressor for compressing natural gas supplied from the outside, a second expander for expanding the fluid passing through the first compressor, a third expander for expanding the fluid further expanded by the second expander, A third expansion unit of the third compander, a second heat exchanger that uses the fluid expanded by the third expansion unit as a refrigerant, a third heat exchanger that compresses the fluid used as the refrigerant in the second heat exchanger, And a second compression section of the second compander which compresses the fluid compressed by the third compression section again and sends it to the first compressor; A fuel supply system for supplying a part of the natural gas supplied from the outside to the fuel of the engine; And a second valve disposed on a line that directs the evaporated gas in the storage tank to the second heat exchanger to regulate the flow rate and pressure of the evaporated gas sent from the storage tank to the second heat exchanger, system; And the second heat exchanger for cooling the natural gas that has passed through the first compressor by using the first compressor, the refrigerant supplied by the refrigerant system, and the evaporation gas supplied from the storage tank, and the second heat exchanger Wherein the first heat exchanger uses the fluid discharged from the top of the distillation tower as a refrigerant, the refrigerant system is an open loop, and the first compressor Is used in connection with the fuel supply system.

The fuel supply system may further include a second compressor for further compressing the natural gas compressed by the first compressor and sending the compressed natural gas to the fuel supply system.

Wherein a portion of the natural gas supplied from the outside can be branched at a front end of the first compressor and sent to a low pressure fuel supply system and the natural gas compressed by the first compressor and the second compressor is supplied to a high- Can be sent to the system.

The liquefaction system may further include a second gas-liquid separator for separating the liquefied natural gas passing through the second heat exchanger and the expansion means and the natural gas remaining in the gaseous state, The liquefied natural gas separated by the second gas-liquid separator can be sent to the storage tank, and the natural gas separated by the second gas-liquid separator can be sent to the refrigerant system.

The refrigerant system may further include a third gas-liquid separator for separating the liquefied natural gas liquefied by the second expansion part and the natural gas remaining in the gaseous state, and the liquefied natural gas separated by the third gas- The gas may be sent to the second heat exchanger and used as a refrigerant, and the natural gas separated by the third gas-liquid separator may be sent to the third expansion unit.

Wherein the refrigerant system further comprises: a third heat exchanger for liquefying the fluid expanded by the second expansion unit and sending it to the third gas-liquid separator; And a fourth compressor for compressing the fluid passing through the third heat exchanger, wherein the third heat exchanger uses the fluid that has passed through the second expansion part as a refrigerant, and passes through the second expansion part The fluid passing through the third heat exchanger and the fourth compressor can be cooled.

According to another aspect of the present invention, there is provided a method for separating heavy hydrocarbons from a fluid cooled by heat exchange with a fluid discharged from a distillation tower by heat exchange with a fluid discharged from a distillation tower, The separated hydrocarbons are expanded and sent to the upper portion of the distillation tower, the separated heavy hydrocarbon is sent to the central portion of the distillation tower, the condensate is separated by the distillation tower, and the fluid discharged from the upper portion of the distillation tower is supplied The natural gas is cooled by the natural gas supplied from the outside of the system, and the fluid used as the refrigerant for cooling the natural gas supplied from the outside of the system is compressed using the energy released when the heavy hydrocarbon is expanded, And used as the refrigerant of the heat exchange, A portion of the fluid being sent to a low pressure fuel supply system and the other portion being compressed and cooled again, and the further compressed and cooled fluid is diverted into two streams, (Hereinafter referred to as 'a flow') is branched again into two flows, and one of the branched a flows (hereinafter referred to as 'b flow' (Hereinafter, referred to as "c flow") of the branched a flows, and the b stream is cooled by the refrigerant Wherein the c flow that has been heat exchanged with the c flow is expanded and partially or fully liquefied and then the b flow that is heat exchanged with the c flow is compressed by the energy released when the b flow is expanded It is a ball.

The c-flow heat exchanged with the b-flow as the refrigerant is expanded and partly or wholly liquefied, the liquid phase and the gas phase are separated, and the separated liquefied natural gas can be sent to the storage tank, Again with the gas, as the refrigerant that cools the c stream.

The b-flow is such that the liquid phase and the gaseous phase are separated and the separated liquefied natural gas can be heat-exchanged as a refrigerant for cooling the c-flow after the compression and cooling, and the separated natural gas is further expanded, And can be heat-exchanged as a refrigerant for cooling the flow.

The expanded b-flow may be heat-exchanged as a refrigerant that is compressed and cooled after being heat-exchanged as a refrigerant (hereinafter referred to as "d-flow"), self-heat-exchanged with the d-flow, and then cooled the c-flow.

According to the present invention, since a separate refrigerant system is not used, there is an advantage that the system is simple and convenient to operate.

In addition, a system using the liquefied natural gas itself as a refrigerant can be roughly divided into a closed loop and an open loop. Since the present invention uses an open loop, The control of the refrigerant system is simple and the components of the system are simple.

Since the energy obtained by cooling the natural gas in the expander of the compander can be used to compress the natural gas in the compressor connected to the expansion part and the shaft, Can be reduced to a minimum.

Further, since the present invention uses evaporative gas as a refrigerant for liquefying natural gas without installing a separate liquefaction facility, it is possible to reduce the installation cost and recover the cold and hot of the evaporative gas.

In addition, since the natural gas liquefaction system is linked with the engine fuel supply system, the present invention can supply natural gas at a pressure required by the engine as fuel without separately installing a compressor for supplying fuel to the engine.

1 is a schematic view showing a ship including a storage tank according to a first preferred embodiment of the present invention.
2 is a schematic view showing a ship including a storage tank according to a second preferred embodiment of the present invention.
3 is a schematic view showing a ship including a storage tank according to a third preferred embodiment of the present invention.
4 is a schematic view showing a ship including a storage tank according to a fourth preferred embodiment of the present invention.
5 is a graph schematically illustrating the phase change of methane with temperature and pressure.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. The vessel including the storage tank of the present invention can be applied to various applications on ships equipped with liquefied natural gas storage tanks and onshore. In addition, the following examples can be modified in various forms, and the scope of the present invention is not limited to the following examples.

1 is a schematic view showing a ship including a storage tank according to a first preferred embodiment of the present invention.

The term "fluid" in this embodiment means a natural gas, a liquefied natural gas, or a mixture of natural gas and liquefied natural gas. The natural gas, which was gaseous when supplied to the system, passes through each device and can become gas, liquid or vapor-liquid mixed depending on the pressure and temperature. Hereinafter, the same applies.

Referring to FIG. 1, a ship including the storage tank of the present embodiment includes a first heat exchanger 305 for exchanging natural gas supplied to the system with a refrigerant to cool the system; A first gas-liquid separator 405 for separating heavy hydrocarbons from the cooled fluid passing through the first heat exchanger 305; A first compander 500 for compressing the fluid heat-exchanged as a refrigerant in the first heat exchanger 305, or for expanding the fluid in which the heavy hydrocarbons are separated by the first gas-liquid separator 405; A first cooler (200) for cooling the fluid compressed by the first compander (500); A distillation column 900 for separating the fluid passing through the first gas-liquid separator 405 by the difference in boiling point; A first valve (700) for regulating the flow rate and pressure of the medium hydrocarbon sent from the first gas-liquid separator (405) to the distillation tower (900); A first compressor (110) for compressing the fluid that has been compressed by the first compander (500) and then passed through the first cooler (200); A second cooler 210 for cooling the natural gas compressed by the first compressor 110; A second compressor 115 for compressing the natural gas having passed through the first compressor 110 and the second cooler 210 and sending the compressed natural gas to the high-pressure fuel supply system; A third cooler 215 for cooling the natural gas that has passed through the second compressor 115; A second compander 510 and a third compander 520 for expanding or compressing the fluid; A second heat exchanger (310) for cooling the natural gas using the expanded fluid and the evaporation gas as refrigerant; Expansion means (600) for expanding the fluid having passed through the second heat exchanger (310); A fourth cooler 220 for cooling the fluid passing through the second compander 510; A fifth cooler 230 for cooling the fluid passing through the third compander 520; And a second valve (20) installed on the line for sending the evaporated gas in the storage tank (10) to the second heat exchanger (310).

It is preferable that a plurality of the storage tanks 10 installed in the ship of the present embodiment are a membrane type storage tank which is installed side by side in the longitudinal direction of the hull and is easy to utilize the inner space of the hull. The evaporated gas generated in the storage tank 10 is sent from the third compander 520 to the second heat exchanger 310 on the line to which the fluid is supplied and flows from the third compander 520 to the second heat exchanger 310 And is used as a refrigerant for cooling the natural gas in the second heat exchanger 310. [ In addition, the fluid which has been heat-exchanged with the refrigerant in the second heat exchanger 310 and then cooled and expanded by the expansion means 600 and partially or completely liquefied is sent to the storage tank 10.

The first heat exchanger 305 of this embodiment exchanges natural gas supplied from the outside of the system with the fluid discharged from the distillation tower 900. That is, the first heat exchanger 305 uses the fluid discharged from the distillation tower 900 as a refrigerant to cool the natural gas supplied from the outside of the system. The medium-hydrocarbon component is separated from the fluid cooled by the first heat exchanger (305) by the first gas-liquid separator (405).

Natural gas separated from the crude oil drilled in the sea bed is subjected to various pretreatment processes and then liquefied to be liquefied natural gas. Natural gas supplied from the outside of the system to the first heat exchanger 305 is discharged from a dryer It may be natural gas that has undergone moisture drying process.

The first gas-liquid separator 405 of this embodiment separates the heavy hydrocarbon component from the fluid cooled by the first heat exchanger 305 and supplies it to a fluid having a high proportion of heavy hydrocarbon components (hereinafter simply referred to as " (Including a case where the ratio of heavy hydrocarbons is high) is sent to the central portion of the distillation column 900, and a fluid having a high methane content by removing the heavy hydrocarbon component To the first compander 500.

The first compander 500 of the present embodiment includes a first expansion unit 501 for expanding the fluid sent from the first gas-liquid separator 405 after most of the heavy hydrocarbon components are separated by the first gas-liquid separator 405; And a first compression unit (502) for compressing the fluid used as the refrigerant in the first heat exchanger (305). The first compression section 502 and the first expansion section 501 of the present embodiment are connected by an axis so that the first compression section 502 is compressed by the energy obtained by expanding the fluid by the first expansion section 501, .

The first cooler 200 of this embodiment is compressed by the first compression unit 502 and lowers the temperature of the fluid as well as the pressure. The first cooler 200 can, for example, cool natural gas by heat-exchanging natural gas with fresh water at about room temperature.

The distillation tower 900 of this embodiment separates the medium hydrocarbon separated from the first gas-liquid separator 405 and the fluid sent from the first expansion unit 501 by components and sends the condensate to a tank for storing the condensate, Is sent to the first heat exchanger (305).

The distillation tower 900 is a device made by using the principle of fractional distillation, which is a method of separating a mixed liquid mixture by boiling point difference, and is also used for separation of crude oil. Crude oil contains liquids with different boiling points, such as petroleum gas, gasoline, naphtha, kerosene, light oil, heavy oil and lubricating oil. When crude oil is placed under the distillation tower and heated, it is separated according to the difference in boiling point. Therefore, the liquid vaporized at a high temperature can be obtained at a low position of the distillation column, and the liquid vaporized at a low temperature can be obtained at a high position of the distillation column. You can separate the crude oil by piping gas at each location and liquefying it again. The distillation column is used to separate the liquid mixture by boiling point difference.

The distillation tower 900 of this embodiment does not separate the crude oil itself but separates the condensate and the like from the natural gas already separated from the crude oil to increase the methane ratio of the natural gas. The term "condensate" refers to a super-light oil (liquid hydrocarbon) that is generally used in a gas state in a variety of ways but is liquid in a gaseous state, and includes paraffinic compounds such as pentane, hexane, heptane and octane.

The distillation column 900 of the present embodiment may further include a reboiler 910. [ A reboiler is a device for heating and evaporating fluid at the bottom of a distillation tower, also known as a distillation kiln or reboiler. The reboiler 910 may be installed separately from the distillation column 900. The reboiler 910 may be installed separately from the distillation column 900. In this embodiment,

The vessel including the storage tank of this embodiment includes a sixth cooler 205 for cooling the condensate discharged from the distillation column 900; And a third valve 705 for controlling the flow rate and pressure of the condensate discharged from the distillation tower 900. The sixth cooler 205 can cool the condensate by, for example, heat-exchanging fresh water at about room temperature with natural gas.

The first valve 700 of this embodiment is installed on a line for sending heavy hydrocarbons from the first gas-liquid separator 405 to the distillation tower 900 to regulate the flow rate and pressure of the heavy hydrocarbons.

The first compressor 110 of this embodiment compresses the fluid that has passed through the first cooler 200 after being compressed by the first compander 500. The vessel including the storage tank of this embodiment is for liquefying the natural gas having passed through the first compressor 110 through the second heat exchanger 310 and the expansion means 600 and sending it to the storage tank 10, The natural gas is compressed by the first compressor 110 before being sent to the second heat exchanger 310 in order to increase the liquefaction efficiency in the second heat exchanger 310. A more detailed explanation is as follows.

5 is a graph schematically illustrating the phase change of methane with temperature and pressure. Referring to FIG. 5, methane enters a supercritical fluid state at a temperature of approximately -80 DEG C or higher and a pressure of approximately 50 bar or more. That is, in the case of methane, the critical point is about -80 ° C, 50 bar. The supercritical fluid state is a third state different from the liquid state or gas state.

However, in the course of re-liquefaction of the evaporated gas, the natural gas may contain a nitrogen component. Depending on the content of nitrogen, the critical point may be changed.

On the other hand, if the temperature is lower than the critical point at a pressure higher than the critical point, the state of the supercritical fluid may be similar to that of the supercritical fluid, which is different from the general liquid state. , Hereinafter referred to as "high pressure liquid state ".

5, natural gas in a relatively low-pressure state (X in FIG. 5) is passed through the second heat exchanger 310 and the expansion means 600 to lower the temperature and pressure, (X 'of FIG. 5). However, it can be seen that even if the temperature and pressure are lowered equally after increasing the pressure of the gas (Y in FIG. 5) have. That is, as the natural gas pressure increases before the natural gas passes through the second heat exchanger 310, the liquefaction efficiency increases. If the pressure can be sufficiently increased (Z in FIG. 5) (Z 'in Fig. 5).

Accordingly, the ship including the storage tank of the present embodiment includes the first compressor 110 to increase the pressure of the natural gas before sending the natural gas to the second heat exchanger 310, and the second heat exchanger 310, Thereby increasing the liquefaction efficiency. The first compressor 110 of the present embodiment preferably compresses the natural gas at a pressure of about 50 bar or more so that the natural gas can be in a supercritical state.

The second cooler 210 of the present embodiment lowers the temperature of the natural gas which has passed through the first compressor 110 and has increased in temperature as well as pressure. The second cooler 210 can cool the natural gas by, for example, heat-exchanging natural gas with fresh water at about room temperature.

The second compressor 115 of the present embodiment compresses the natural gas that has passed through the first compressor 110 and the second cooler 210 to a pressure required by the engine installed on the ship and sends it to the high-pressure fuel supply system.

The third cooler 215 of the present embodiment is installed at the downstream end of the second compressor 115 and passes through the second compressor 115 and lowers the temperature of the natural gas not only in pressure but also in temperature. The third cooler 215 can cool the fluid by, for example, heat-exchanging the fluid with fresh water at about room temperature.

The second compander 510 of the present embodiment includes a second expanding section 512 for expanding the fluid and a second compressing section 511 for compressing the fluid. The second expanding part 512 and the second compressing part 511 are connected by an axis so that the second compressing part 511 compresses the fluid by the energy obtained by expanding the fluid by the second expanding part 512 do. Since the ship including the storage tank of this embodiment compresses and expands the fluid by using the compander, the energy released as the fluid expands can be used for compressing the fluid, so that energy can be efficiently used.

The second expansion unit 512 of the second compander 510 expands a portion of the natural gas that has passed through the first compressor 110 and the second compressor 210 and then sends it to the third compander 520 The second compressor 511 compresses the fluid sent from the third compander 520 and sends it to the first compressor 110 again.

The third compander 520 of the present embodiment includes a third expanding section 522 for expanding the fluid and a third compressing section 521 for compressing the fluid, like the second compander 510. The third expanding portion 522 and the third compressing portion 521 are connected by a shaft like the second expanding portion 512 and the second compressing portion 511 so that the third expanding portion 522 The third compression section 521 compresses the fluid by the energy obtained by expanding the fluid.

The third expanding portion 522 of the third compander 520 is configured to expand the fluid primarily expanded by the second expanding portion 512 of the second compander 510, (310). The fluid expanded by the second expanding section 512 and the third expanding section 522 flows together with the evaporated gas discharged from the storage tank 10 into the second heat exchanger 310 as a refrigerant for cooling the natural gas Is used. The third compression unit 521 of the third compander 520 compresses the fluid used as the refrigerant in the second heat exchanger 310 and sends it to the second compander 510.

The second heat exchanger 310 of the present embodiment is configured so that a portion of the natural gas that has passed through the first compressor 110 and the second cooler 210 is divided into the second expansion portion 512 and the third expansion portion 522 And is cooled by self-heat exchange with the passing fluid and the evaporated gas discharged from the storage tank 10. Self-cooling means that a part of the natural gas is cooled without using a separate refrigerant, and the natural gas itself is used as a refrigerant for cooling the natural gas.

The ship including the storage tank of the present embodiment liquefies part of the natural gas that has passed through the first compressor 110 and the second cooler 210 by the second heat exchanger 310 and the expansion means 600 The fluid used as the refrigerant in the second heat exchanger 310 is supplied to the storage tank 10 by the second expansion portion 512 and the third expansion portion 522, To a sufficiently low temperature.

In addition, the ship including the storage tank of the present embodiment uses the evaporation gas generated in the storage tank 10 as a refrigerant for cooling the natural gas in the second heat exchanger 310 and the second refrigerant in the second heat exchanger 310 It is possible to increase the liquefaction efficiency.

The expansion means (600) of the present embodiment lowers the pressure of the fluid whose temperature has been lowered by the heat exchange in the second heat exchanger (310). The natural gas is partly or entirely liquefied while passing through the second heat exchanger 310 and the expansion means 600 and the liquefied natural gas is mixed with the natural gas remaining in the gaseous state in a vapor-liquid mixed state The liquefied natural gas is sent to the storage tank 10. The expansion means 600 may be an expansion valve or an expander.

The fourth cooler 220 of the present embodiment is disposed at the downstream end of the third compressing section 521 of the third compander 520 so as to pass through the third compressing section 521 and not only the pressure but also the temperature . The fluid that has passed through the third compression unit 521 and the fourth cooling unit 220 is sent to the second compander 510.

The fifth cooler 230 of the present embodiment is disposed at the downstream end of the second compressing section 511 of the second compander 510 so as to allow the temperature of the fluid passing through the second compressing section 511, . The fluid having passed through the second compression unit 511 and the fifth cooling unit 230 is sent to the first compressor 110.

The fourth cooler 220 and the fifth cooler 230 of this embodiment can cool the fluid by, for example, heat-exchanging the fluid with the fresh water at about room temperature.

The second valve 20 of the present embodiment is installed on a line for sending the evaporated gas inside the storage tank 10 to the second heat exchanger 310 and is supplied from the storage tank 10 to the second heat exchanger 310 Adjust the flow rate and pressure of the vapor to be sent. The second valve 20 is opened when the internal pressure of the storage tank 10 is higher than the set value according to the value sent from the sensor for measuring the pressure inside the storage tank 10, And to be closed if it is lower.

The flow of the fluid in this embodiment will be described as follows.

The natural gas supplied from the outside of the system is heat-exchanged with the refrigerant in the first heat exchanger 305 and is cooled and then sent to the first gas-liquid separator 405. After the heavy hydrocarbons are separated by the first gas-liquid separator 405 Is sent to the first expansion portion 501 of the first compander 500 and the fluid expanded by the first expansion portion 501 is sent to the upper portion of the distillation column 900. The heavy hydrocarbons separated by the first gas-liquid separator 405 pass through the first valve 700 and then are sent to the central portion of the distillation tower 900.

The fluid having a lower temperature discharged from the upper portion of the distillation tower 900 by the fractional distillation by the distillation tower 900 is used as a refrigerant for cooling the natural gas supplied from the outside of the system to the first heat exchanger 305, And sent to the first compression unit 502 of the first compander 500. The fluid sent to the first compression unit 502 is expanded by the first compression unit 502, cooled by the first cooling unit 200, and then sent to the first compressor 110. On the other hand, the condensate separated by the distillation column 900 may be cooled by the sixth cooler 205 and then sent to the condensate storage tank via the third valve 705.

The fluid expanded by the first compression unit 502 and cooled by the first cooler 200 is branched and sent to the low pressure fuel supply system and the remaining part is compressed by the first compressor 110 Cooled by the second cooler 210, and then branched again into two flows.

One of the two streams of natural gas branched after passing through the first compressor 110 and the second cooler 210 passes through the second compressor 115 and the third cooler 215, To the supply system, and the other flow branches again into two flows.

After passing through the first compressor 110 and the second cooler 210, one of the two streams of natural gas that is not sent to the high-pressure fuel supply system but is branched is sent to the second heat exchanger 310, The other stream is sent to the second compander 510. In order to liquefy natural gas sent to the second heat exchanger 310, the natural gas sent to the second compander 510 is liquefied and used as a refrigerant.

The vessel containing the storage tank of the present embodiment can be used as an engine using a relatively low pressure natural gas fuel such as a DF engine requiring a pressure of approximately 6.5 bar and an ME-GI engine requiring a pressure of approximately 300 bar , And an engine using high-pressure natural gas as fuel.

It is inefficient to lower the pressure of the natural gas compressed by the first compressor 110 and use it in the low pressure engine so that the flow of the natural gas through the first compander 500 and the first cooler 200 to a low-pressure fuel supply system and is used as fuel for a low-pressure engine such as a DF engine.

Further, the vessel including the storage tank of the present embodiment may be provided with a first compressor (not shown) which is used to liquefy natural gas so that the fuel supply system does not include a separate compressor or the number of compressors installed in the fuel supply system 110) is used in conjunction with a high-pressure fuel supply system. That is, the natural gas compressed by the first compressor 110 is partially branched and further compressed by the second compressor 115, and then used as fuel for a high-pressure engine such as the ME-GI engine.

In the present embodiment, a case where a part of the natural gas branched after being compressed by the first compressor 110 is compressed by one compressor 115 has been described as an example, A plurality of compressors are installed in a multistage manner on the line for sending the natural gas to the high-pressure fuel supply system, so that the pressure required by the high-pressure engine installed on the ship can be satisfied. Further, a cooler for lowering the temperature of the natural gas passing through each compressor may be provided at a rear end of each of the plurality of compressors.

Natural gas that has passed through the first compressor 110 and the second compressor 210 and then sent to the second compander 510 is expanded by the second expansion unit 512, And is sent to the third expansion portion 522. The fluid once again expanded by the third expansion part 522 is sent to the second heat exchanger 310.

The evaporated gas generated in the storage tank 10 is passed through the second valve 20 and then sent to the second heat exchanger 310 from the third compander 520 via a line Loses.

The evaporation gas sent from the storage tank 10 onto the line through which the fluid is sent from the third compander 520 to the second heat exchanger 310 flows through the second expansion portion 512 and the third expansion portion 522, Exchanged with the natural gas as a refrigerant in the second heat exchanger 310 together with the cooled fluid, and then the cold heat is partially or entirely vaporized by the natural gas. The partially or fully vaporized fluid is again sent to the third compander 520 and compressed by the third compression section 521.

The fluid compressed by the third compression unit 521 is cooled by the fourth cooling unit 220 and then sent to the second compander 510 and compressed again by the second compression unit 511 . The fluid compressed by the second compressing unit 511 is cooled by the fifth cooler 230, and then sent to the first compressor 110 again.

That is, the fluid used as the refrigerant after being expanded by the second expanding section 512 and the third expanding section 522 flows by the second expanding section 512 and the third expanding section 522 When the fluid that has been compressed by the second compressing unit 511 and the third compressing unit 521 and has passed through the first compander 500 and the first cooler 200 is supplied to the first compressor 110 And is sent to the first compressor 110 after recovering the pressure.

The natural gas that has passed through the first compressor 110 and the second cooler 210 and then sent to the second heat exchanger 310 is discharged through the second expansion portion 512 and the third expansion portion 522, And the evaporation gas discharged from the storage tank 10, and then expanded by the expansion means 600. [ The fluid partially or entirely liquefied through the second heat exchanger 310 and the expansion means 600 is sent to the storage tank 10.

2 is a schematic view showing a ship including a storage tank according to a second preferred embodiment of the present invention.

The ship including the storage tank of the second embodiment shown in FIG. 2 is different from the ship including the storage tank of the first embodiment shown in FIG. 1 in that the third compressor 120, the seventh cooler 240, 2 gas-liquid separator 410, a fourth valve 710 and a fifth valve 30, and differences will be mainly described below. A detailed description of the same components as those of the ship including the storage tank of the above-described first embodiment will be omitted.

2, the ship including the storage tank of the present embodiment is provided with a first heat exchanger 305, a first gas-liquid separator 405, a first compander 500, A first compressor 110, a second compressor 210, a second compressor 115, a third condenser 215, a second compressor (not shown) 510, a third compander 520, a second heat exchanger 310, an expansion means 600, a fourth cooler 220, a fifth cooler 230 and a second valve 20.

However, the ship including the storage tank of this embodiment is different from the first embodiment in that the third compressor 120 additionally compresses the natural gas firstly compressed by the first compressor 110; A seventh chiller 240 for lowering the temperature of the natural gas passing through the third compressor 120; A second gas-liquid separator (410) installed at a downstream end of the expansion means (600) for separating liquefied natural gas from natural gas in a gaseous state; A fourth valve 710 for regulating the flow rate and pressure of the gaseous natural gas separated by the second gas-liquid separator 410; And a fifth valve (30) for regulating the flow rate and pressure of the liquefied natural gas separated from the second gas-liquid separator (410) and sent to the storage tank (10).

As in the first embodiment, it is preferable that a plurality of the storage tanks 10 installed in the ship of the present embodiment are a membrane type storage tank which is arranged side by side in the longitudinal direction of the hull and is easy to utilize the inner space of the hull. The evaporated gas generated in the storage tank 10 is sent to the third heat exchanger 310 from the third compander 520 on a line through which the fluid is sent, 520 to the second heat exchanger 310 and the second heat exchanger 310 to cool the natural gas.

However, unlike the first embodiment, the fluid which has been heat-exchanged with the refrigerant in the second heat exchanger 310, expanded by the expansion means 600 and partially or completely liquefied, Liquid separator 410, so that the gas phase and the liquid phase are separated from each other.

The first heat exchanger 305 of this embodiment uses the fluid discharged from the distillation tower 900 as a refrigerant to cool the natural gas supplied from the outside of the system, as in the first embodiment. The medium-hydrocarbon component is separated from the fluid cooled by the first heat exchanger (305) by the first gas-liquid separator (405) as in the first embodiment.

Natural gas supplied from the outside of the system to the first heat exchanger 305 may be natural gas that has undergone a moisture drying process in a dryer as in the first embodiment.

The first gas-liquid separator 405 of this embodiment separates the heavy hydrocarbon component from the fluid cooled by the first heat exchanger 305 and sends the heavy hydrocarbon to the central portion of the distillation column 900 The fluid having the higher methane content removed from the heavy hydrocarbon component is sent to the first compander 500.

As in the first embodiment, the first compander 500 of the present embodiment is provided with a first gas-liquid separator 405 that expands the fluid sent from the first gas-liquid separator 405 after most of the heavy hydrocarbon components are separated by the first gas- 1 expanding portion (501); And a first compression unit (502) for compressing the fluid used as the refrigerant in the first heat exchanger (305). The first compression section 502 and the first expansion section 501 of the present embodiment are connected by an axis like the first embodiment so that the first expansion section 501 can be divided into the first expansion section 501 and the second expansion section 501 by the energy obtained by expanding the fluid. The compression section 502 compresses the fluid.

As in the first embodiment, the first cooler 200 of this embodiment is compressed by the first compression section 502 and lowers the temperature of the fluid not only in pressure but also in temperature.

The distillation tower 900 of the present embodiment separates the medium hydrocarbon separated from the first gas-liquid separator 405 and the fluid sent from the first expanding section 501 by components, and the condensate stores the condensate And the purified natural gas is sent to the first heat exchanger 305 so that the rate of methane is higher.

The distillation tower 900 of this embodiment may further include a reboiler 910 as in the first embodiment and the reboiler 910 may be installed separately from the distillation tower 900.

The vessel including the storage tank of this embodiment includes, as in the first embodiment, a sixth cooler 205 for cooling the condensate discharged from the distillation tower 900; And a third valve 705 for controlling the flow rate and pressure of the condensate discharged from the distillation tower 900.

The first valve 700 of this embodiment is disposed on a line for sending heavy hydrocarbons from the first gas-liquid separator 405 to the distillation tower 900, as in the first embodiment, and regulates the flow rate and pressure of the heavy hydrocarbons .

The first compressor 110 of this embodiment compresses the fluid that has passed through the first cooler 200 after being compressed by the first compander 500 as in the first embodiment, (210) passes through the first compressor (110) and lowers the temperature of natural gas not only in pressure but also in temperature, as in the first embodiment.

The second compressor 115 of the present embodiment compresses the natural gas that has passed through the first compressor 110 and the second cooler 210 to a pressure required by the engine installed on the ship as in the first embodiment, Of fuel supply system.

As in the first embodiment, the third cooler 215 of this embodiment is disposed downstream of the second compressor 115 to lower the temperature of the natural gas that has passed through the second compressor 115 and has increased temperature as well as pressure .

The third compressor 120 of this embodiment further compresses the natural gas that has not been sent to the fuel supply system among the natural gas that has passed through the first compressor 110 and the second cooler 210. [ As described above, it is advantageous in terms of the liquefaction efficiency to increase the pressure of the natural gas before the natural gas passes through the second heat exchanger 310. This is because the first compressor 110 is insufficient for compressing the natural gas to a sufficient pressure In this case, as in the present embodiment, it may further include a compressor. In this embodiment, the natural gas is compressed in two stages. However, a compression process may be added as needed. In addition, the branch point can be determined in consideration of the natural gas to be used as the refrigerant and the required pressure of the natural gas to be liquefied.

The natural gas compressed by the first compressor 110 and the third compressor 120 of the present embodiment preferably has a pressure of about 50 bar or more so as to be in a supercritical state.

The seventh cooler 240 of the present embodiment lowers the temperature of the natural gas that has passed through the third compressor 120 and increased not only in pressure but also in temperature. For example, by exchanging heat between fresh water and natural gas at a room temperature, Natural gas can be cooled.

As in the first embodiment, the second compander 510 of the present embodiment includes a second expanding section 512 for expanding the fluid and a second compressing section 511 for compressing the fluid. The second expanding section 512 and the second compressing section 511 are axially connected to each other in the same manner as in the first embodiment and by the energy obtained by expanding the fluid by the second expanding section 512, (511) compresses the fluid.

The second expansion portion 512 of the second compander 510 expands a part of the natural gas that has passed through the first compressor 110 and the second cooler 210 as in the first embodiment, And the second compressor 511 compresses the fluid sent from the third compander 520 and sends the compressed fluid to the first compressor 110 as in the first embodiment.

As in the first embodiment, the third compander 520 of the present embodiment includes a third expanding section 522 for expanding the fluid and a third compressing section 521 for compressing the fluid. The third expanding section 522 and the third compressing section 521 are connected to each other by the shaft and the third expanding section 522 is connected to the third compressing section 522 by the energy obtained by expanding the fluid 521 compress the fluid.

The third expanding portion 522 of the third compander 520 is configured such that the fluid primarily expanded by the second expanding portion 512 of the second compander 510 is again And then sent to the second heat exchanger 310. The fluid inflated by the second expanding section 512 and the third expanding section 522 together with the evaporated gas discharged from the storage tank 10 in the second heat exchanger 310 It is used as a refrigerant to cool natural gas.

The third compression section 521 of the third compander 520 compresses the fluid used as the refrigerant in the second heat exchanger 310 and sends it to the second compander 510 as in the first embodiment .

The second heat exchanger 310 of the present embodiment is configured to mix the natural gas that has passed through the first compressor 110, the second cooler 210, the third compressor 210 and the seventh cooler 240, The fluid that has passed through the first expansion portion 512 and the third expansion portion 522 and the evaporation gas discharged from the storage tank 10 are cooled by the self-heat exchange.

As in the first embodiment, the expansion means 600 of the present embodiment lowers the pressure of the fluid whose temperature has been lowered by the heat exchange in the second heat exchanger 310 and the natural gas is introduced into the second heat exchanger 310 and the expansion means 600, the liquid is partly or entirely liquefied. The expansion means 600 may be an expansion valve or an expander.

The second gas-liquid separator 410 of this embodiment is installed at the rear end of the expansion means 600 and passes through the second heat exchanger 310 and the expansion means 600 and remains in a gaseous state with a part of liquefied natural gas The natural gas is separated, and the liquefied natural gas is sent to the storage tank 10, and the natural gas is sent from the third expansion part 522 to the second heat exchanger 310 on the line through which the fluid is sent.

The fourth valve 710 of the present embodiment is installed on a line for sending natural gas between the third expansion portion 522 and the second heat exchanger 310 from the second gas-liquid separator 410, Adjust the pressure. That is, the fourth valve 710 controls the amount of fluid flowing through the third expansion portion 522 to the second heat exchanger 310 and the capacity of the second heat exchanger 310, The amount of natural gas sent from the separator 410 to the third expansion part 522 and the second heat exchanger 310 is controlled and the third expansion part 522 is sent to the second heat exchanger 310 Liquid separator 410 to regulate the pressure of the natural gas so that the pressure of the natural gas sent between the third expansion part 522 and the second heat exchanger 310 becomes similar.

The fifth valve 30 of this embodiment is installed on the line for sending the liquefied natural gas separated from the second gas-liquid separator 410 to the storage tank 10 to regulate the flow rate and pressure of the liquefied natural gas.

The fourth compressor 220 of the present embodiment is disposed at the downstream end of the third compression section 521 of the third compander 520 and passes through the third compression section 521 But the temperature also lowers the temperature of the raised fluid. The fluid that has passed through the third compression unit 521 and the fourth cooling unit 220 is sent to the second compander 510.

The fifth cooler 230 of the present embodiment is disposed at the rear end of the second compression section 511 of the second compander 510 and passes through the second compression section 511 and the pressure But the temperature also lowers the temperature of the raised fluid. The fluid having passed through the second compression unit 511 and the fifth cooling unit 230 is sent to the first compressor 110.

The second valve 20 of the present embodiment is provided on the line for sending the vaporized gas in the storage tank 10 to the second heat exchanger 310 and is supplied from the storage tank 10 2 heat exchanger (310).

The flow of the fluid in this embodiment will be described as follows.

The natural gas supplied from the outside of the system is subjected to heat exchange with the refrigerant in the first heat exchanger 305 to be cooled and then sent to the first gas-liquid separator 405 as in the first embodiment, After the middle hydrocarbon component is separated and sent to the first expanding portion 501 of the first compander 500 and the fluid expanded by the first expanding portion 501 flows into the distillation tower 900 ). The heavy hydrocarbons separated by the first gas-liquid separator 405 are sent to the central portion of the distillation column 900 after passing through the first valve 700, as in the first embodiment.

The fluid which has been subjected to fractional distillation by the distillation tower 900 and whose temperature is lowered from the upper part of the distillation tower 900 is sent to the first heat exchanger 305 in the same manner as in the first embodiment to cool the natural gas supplied from the outside of the system And then sent to the first compression unit 502 of the first compander 500. [ The fluid sent to the first compression section 502 is expanded by the first compression section 502 and cooled by the first condenser 200 and then sent to the first compressor 110 as in the first embodiment . On the other hand, the condensate separated by the distillation column 900 may be cooled by the sixth cooler 205 and then sent to the condensate storage tank via the third valve 705, as in the first embodiment.

The fluid expanded by the first compression section 502 and cooled by the first cooler 200 is branched to a low-pressure fuel supply system in the same manner as in the first embodiment, Compressed by the first cooler 110, cooled by the second cooler 210, and then branched again into two flows.

The natural gas compressed by the first compressor 110, cooled by the second cooler 210, and then diverted to the two flows again is supplied to the second compressor 115 and the second compressor 115 as in the first embodiment. 3 cooler 215 and then to a high-pressure fuel supply system, and the other flow branches again into two flows.

Unlike the first embodiment, the natural gas, which has passed through the first compressor 110 and the second cooler 210 and then branched into two flows without being sent to the high-pressure fuel supply system, 2 heat exchanger 310 but is sent to the second heat exchanger 310 after passing through the third compressor 120 and the seventh cooler 240 and the other flow is the same as in the first embodiment And then sent to the second compander 510.

Also, as in the first embodiment, the ship including the storage tank of this embodiment uses the first compressor 110 used for liquefying natural gas in conjunction with the high-pressure fuel supply system, and the first compressor 110 A plurality of compressors and a plurality of coolers, which are additionally installed on the line for sending the natural gas compressed by the high-pressure fuel supply system to the high-pressure fuel supply system.

Natural gas that has passed through the first compressor 110 and the second cooler 210 and then sent to the second compander 510 is expanded by the second expansion unit 512, 3 compander 520 to the third expander 522 of the compander 520. [ The fluid once again expanded by the third expanding section 522 is sent to the second heat exchanger 310 as in the first embodiment.

Meanwhile, the evaporated gas generated in the storage tank 10 flows from the third compander 520 to the second heat exchanger 310 after passing through the second valve 20, as in the first embodiment, Is sent on the line to be sent.

The evaporated gas sent from the storage tank 10 onto the line through which the fluid is sent from the third compander 520 to the second heat exchanger 310 flows through the second expansion portion 512 and the second expansion portion 512, The partially or fully vaporized, partially or fully vaporized fluid after heat exchange with the natural gas in the second heat exchanger 310, together with the cooled fluid passing through the third expansion portion 522, The second compander 520 is again compressed by the third compression unit 521. [

The fluid compressed by the third compression section 521 is cooled by the fourth cooler 220 and then sent again to the second compander 510 as in the first embodiment so that the second compression section 511, Lt; / RTI > The fluid compressed by the second compression unit 511 is cooled by the fifth cooler 230 and then sent to the first compressor 110 again in the same manner as in the first embodiment, .

The natural gas that has passed through the first compressor 110 and the second cooler 210 and then branched and passed through the third compressor 120 and the seventh cooler 240 is sent to the second heat exchanger 310, Exchanged with the fluid expanded by the second expansion portion 512 and the third expansion portion 522 and the evaporation gas discharged from the storage tank 10, and then expanded by the expansion means 600. [

Unlike the first embodiment, the fluid that has partially or completely liquefied through the second heat exchanger 310 and the expansion means 600 is not sent directly to the storage tank 10 in a vapor-liquid mixed state, 2 gas-liquid separator 410 separates the liquid phase and the gas phase. The liquefied natural gas separated by the second gas-liquid separator 410 is sent to the storage tank 10 after passing through the fifth valve 30 and the natural gas separated by the second gas- 4 valve 710 and then sent to the second heat exchanger 310 together with the fluid that has passed through the third expansion portion 522 and is used again as a refrigerant.

3 is a schematic view showing a ship including a storage tank according to a third preferred embodiment of the present invention.

The ship including the storage tank of the third embodiment shown in Fig. 3 has the third gas-liquid separator 420 and the sixth valve 720 as compared with the ship including the storage tank of the second embodiment shown in Fig. There is a difference therebetween. In the following, the difference will be mainly described. A detailed description of the same components as those of the ship including the storage tank of the second embodiment described above will be omitted.

3, the vessel including the storage tank according to the present embodiment is provided with a first heat exchanger 305, a first gas-liquid separator 405, a first compander 500, The first compressor 110, the second compressor 210, the second compressor 115, the third cooler 215, the third compressor 120, the first condenser 110, the second condenser 115, A third compressor 520, a second heat exchanger 310, an expansion device 600, a second gas-liquid separator 410, a fourth valve (not shown) A third valve 710, a fifth valve 30, a fourth cooler 220, a fifth cooler 230, and a second valve 20.

However, unlike the second embodiment, the vessel including the storage tank of the present embodiment is installed between the second bulging portion 512 and the third bulging portion 522 and passes through the second bulging portion 512 A third gas-liquid separator (420) for separating the partially liquefied natural gas and the natural gas remaining in the gaseous state; And a sixth valve (720) for regulating the flow rate and pressure of the liquefied natural gas separated by the third gas-liquid separator (420) and sent to the second heat exchanger (310).

Like the second embodiment, it is preferable that the storage tank 10 installed in the ship of this embodiment is a membrane type storage tank in which a plurality of the storage tanks 10 are installed side by side in the longitudinal direction of the hull, and the space inside the hull is easy to use. The evaporated gas generated in the storage tank 10 is sent to the third heat exchanger 310 from the third compander 520 on the line through which the fluid is sent, 520 to the second heat exchanger 310 and the second heat exchanger 310 to cool the natural gas.

The first heat exchanger 305 of this embodiment uses the fluid discharged from the distillation tower 900 as a refrigerant to cool the natural gas supplied from the outside of the system, as in the second embodiment. As for the fluid cooled by the first heat exchanger 305, the heavy hydrocarbon component is separated by the first gas-liquid separator 405 as in the second embodiment.

The natural gas supplied from the outside of the system to the first heat exchanger 305 may be a natural gas that has undergone a moisture drying process in a dryer as in the second embodiment.

The first gas-liquid separator 405 of this embodiment separates the heavy hydrocarbon component from the fluid cooled by the first heat exchanger 305 and sends the heavy hydrocarbon to the central portion of the distillation column 900 The fluid having the higher methane content removed from the heavy hydrocarbon component is sent to the first compander 500.

As in the second embodiment, the first compander 500 of the present embodiment is configured to expand the fluid sent from the first gas-liquid separator 405 after most of the heavy hydrocarbon components are separated by the first gas-liquid separator 405, 1 expanding portion (501); And a first compression unit (502) for compressing the fluid used as the refrigerant in the first heat exchanger (305). The first compression section 502 and the first expansion section 501 of the present embodiment are connected by an axis like the second embodiment so that the energy of the first expansion section 501, The compression section 502 compresses the fluid.

As in the second embodiment, the first cooler 200 of this embodiment is compressed by the first compression section 502 and lowers the temperature of the fluid not only in pressure but also in temperature.

The distillation column 900 of the present embodiment separates the medium hydrocarbon separated from the first gas-liquid separator 405 and the fluid sent from the first expanding section 501 by the component in the same manner as the second embodiment and the condensate stores the condensate And the purified natural gas is sent to the first heat exchanger 305 so that the rate of methane is higher.

The distillation tower 900 of this embodiment may further include a reboiler 910 as in the second embodiment and the reboiler 910 may be installed separately from the distillation tower 900.

The vessel including the storage tank of this embodiment includes, as in the second embodiment, a sixth cooler 205 for cooling the condensate discharged from the distillation tower 900; And a third valve 705 for controlling the flow rate and pressure of the condensate discharged from the distillation tower 900.

The first valve 700 of this embodiment is disposed on a line for sending heavy hydrocarbons from the first gas-liquid separator 405 to the distillation tower 900, and regulates the flow rate and pressure of the heavy hydrocarbons .

The first compressor 110 of the present embodiment compresses the fluid that has passed through the first cooler 200 after being compressed by the first compander 500 as in the second embodiment, (210) passes through the first compressor (110) and lowers the temperature of the natural gas not only in pressure but also in temperature, as in the second embodiment.

The second compressor 115 of the present embodiment compresses the natural gas that has passed through the first compressor 110 and the second cooler 210 to a pressure required by the engine installed on the ship, Of fuel supply system.

Like the second embodiment, the third cooler 215 of this embodiment is disposed downstream of the second compressor 115 to lower the temperature of the natural gas that has passed through the second compressor 115 and has increased temperature as well as pressure .

The third compressor 120 of this embodiment additionally compresses some of the natural gas that has passed through the first compressor 110 and the second cooler 210 as in the second embodiment. The natural gas compressed by the first compressor 110 and the third compressor 120 of the present embodiment preferably has a pressure of about 50 bar or more so as to be in a supercritical state.

As in the second embodiment, the seventh cooler 240 of the present embodiment lowers the temperature of the natural gas that has passed through the third compressor 120 and has increased temperature as well as pressure.

As in the second embodiment, the second compander 510 of the present embodiment includes a second expanding section 512 for expanding the fluid and a second compressing section 511 for compressing the fluid. The second expanding section 512 and the second compressing section 511 are axially connected to each other in the same manner as in the second embodiment and by the energy obtained by expanding the fluid by the second expanding section 512, (511) compresses the fluid.

Unlike the second embodiment, the second expansion unit 512 of the second compander 510 inflates a part of the natural gas that has passed through the first compressor 110 and the second cooler 210, Liquid separator 420, not directly to the third compander 520.

The second compressor 511 of the second compander 510 compresses the fluid sent from the third compander 520 and sends it to the first compressor 110 as in the second embodiment.

The third gas-liquid separator 420 of this embodiment separates the partially liquefied natural gas and the natural gas remaining in the gaseous state through the second expansion portion 512, and the liquefied natural gas is separated from the second heat exchanger 310 To be used as a refrigerant, and the natural gas is sent to the third compander 520 to be further expanded by the third expansion part 522.

The vessel including the storage tank of this embodiment allows the liquefied natural gas separated by the third gas-liquid separator 420 including the third gas-liquid separator 420 to be used as the refrigerant in the second heat exchanger 310 The liquefaction efficiency in the second heat exchanger 310 can be higher than in the first and second embodiments.

The sixth valve 720 of the present embodiment is installed on the line for sending the liquefied natural gas separated by the third gas-liquid separator 420 to the second heat exchanger 310 to control the flow rate and pressure of the liquefied natural gas do. In consideration of the flow rate of the fluid passing through the third expansion portion 522 and sent to the second heat exchanger 310 and the capacity of the second heat exchanger 310, The amount of liquefied natural gas sent from the separator 420 to the second heat exchanger 310 is controlled and the temperature of the liquefied natural gas used as the refrigerant in the second heat exchanger 310 is further lowered to the second heat exchanger 310 Liquid separator 420 to be further expanded to the liquefied natural gas to be sent to the second heat exchanger 310 so as to increase the liquefaction efficiency in the second gas-liquid separator 420.

As in the second embodiment, the third compander 520 of the present embodiment includes a third expanding section 522 for expanding the fluid and a third compressing section 521 for compressing the fluid. Similarly to the second embodiment, the third expanding section 522 and the third compressing section 521 are axially connected to each other so that the energy of the third expanding section 522 expanding the fluid causes the third compressing section 521 compress the fluid.

The third expansion part 522 of the third compander 520 is expanded primarily by the second expansion part 512 of the second compander 510 but can not be liquefied, The natural gas separated by the natural gas is again expanded and sent to the second heat exchanger 310. The fluid inflated by the second expanding section 512 and the third expanding section 522 flows in the second heat exchanger 310 together with the evaporated gas discharged from the storage tank 10 as in the second embodiment It is used as a refrigerant to cool natural gas.

The third compression section 521 of the third compander 520 compresses the fluid used as the refrigerant in the second heat exchanger 310 and sends it to the second compander 510 as in the second embodiment .

The second heat exchanger 310 of the present embodiment is configured such that the first compressor 110, the second cooler 210, the third compressor 210, and the seventh cooler 240, Gas is cooled by self-heat exchange with the fluid that has passed through the second expansion portion 512, the third expansion portion 522, and the evaporation gas discharged from the storage tank 10.

However, unlike the second embodiment, the second heat exchanger 310 of the present embodiment differs from the second embodiment in that the fluid that has passed both the second expanding section 512 and the third expanding section 522 and the fluid that has been discharged from the storage tank 10 Liquid natural gas separated by the third gas-liquid separator 420 after being passed through the second expansion portion 512 is also used as a refrigerant.

As in the second embodiment, the expansion means 600 of the present embodiment lowers the pressure of the fluid whose temperature has been lowered by the heat exchange in the second heat exchanger 310, and the natural gas is introduced into the second heat exchanger 310 and the expansion means 600, the liquid is partly or entirely liquefied. The expansion means 600 may be an expansion valve or an expander.

The second gas-liquid separator 410 of the present embodiment is disposed at the rear end of the expansion means 600 and passes through the second heat exchanger 310 and the expansion means 600 and is partly liquefied natural The liquefied natural gas is sent to the storage tank 10, and the natural gas is supplied to the second heat exchanger 310 from the line- Lt; / RTI >

The fourth valve 710 of the present embodiment is installed on the line for sending natural gas between the third expansion portion 522 and the second heat exchanger 310 from the second gas-liquid separator 410 as in the second embodiment Thereby controlling the flow rate and pressure of the natural gas.

The fifth valve 30 of this embodiment is installed on a line for sending the liquefied natural gas separated from the second gas-liquid separator 410 to the storage tank 10 as in the second embodiment so that the flow rate of the liquefied natural gas And pressure.

The fourth cooler 220 of the present embodiment is disposed at the rear end of the third compression section 521 of the third compander 520 and passes through the third compression section 521 to generate pressure only But the temperature also lowers the temperature of the raised fluid. The fluid that has passed through the third compression unit 521 and the fourth cooling unit 220 is sent to the second compander 510.

The fifth cooler 230 of the present embodiment is installed at the rear end of the second compressing section 511 of the second compander 510 and passes through the second compressing section 511, But the temperature also lowers the temperature of the raised fluid. The fluid having passed through the second compression unit 511 and the fifth cooling unit 230 is sent to the first compressor 110.

The second valve 20 of the present embodiment is provided on the line for sending the vaporized gas in the storage tank 10 to the second heat exchanger 310 as in the second embodiment, 2 heat exchanger (310).

The flow of the fluid in this embodiment will be described as follows.

The natural gas supplied from the outside of the system is subjected to heat exchange with the refrigerant in the first heat exchanger 305 after being cooled and then sent to the first gas-liquid separator 405 as in the second embodiment, After the middle hydrocarbon component is separated and sent to the first expanding section 501 of the first compander 500 and the fluid expanded by the first expanding section 501 flows into the distillation column 900 ). The heavy hydrocarbons separated by the first gas-liquid separator 405 are sent to the central portion of the distillation column 900 after passing through the first valve 700, as in the second embodiment.

The fluid which has been subjected to fractional distillation by the distillation tower 900 and whose temperature is lowered from the upper part of the distillation tower 900 is sent to the first heat exchanger 305 and cooled And then sent to the first compression unit 502 of the first compander 500. [ The fluid sent to the first compression section 502 is expanded by the first compression section 502 and cooled by the first cooling device 200 and then sent to the first compressor 110 as in the second embodiment . On the other hand, the condensate separated by the distillation tower 900 may be cooled by the sixth cooler 205 and then sent to the condensate storage tank via the third valve 705, as in the second embodiment.

The fluid expanded by the first compression section 502 and cooled by the first cooler 200 is branched to a low pressure fuel supply system in the same manner as in the second embodiment, Compressed by the first cooler 110, cooled by the second cooler 210, and then branched again into two flows.

Natural gas, which is compressed by the first compressor 110, cooled by the second cooler 210, and then diverted into two flows, flows in the same direction as the second embodiment, 3 cooler 215 and then to a high-pressure fuel supply system, and the other flow branches again into two flows.

After passing through the first compressor 110 and the second cooler 210, the natural gas which is not sent to the high-pressure fuel supply system but is diverted into two flows, as in the second embodiment, flows in the third compressor 120 and the seventh cooler 240 and then to the second heat exchanger 310 and the other stream is sent to the second compander 510. [

Also, as in the second embodiment, the ship including the storage tank of this embodiment uses the first compressor 110 used for liquefying natural gas in conjunction with the high-pressure fuel supply system, and the first compressor 110 A plurality of compressors and a plurality of coolers, which are additionally installed on the line for sending the natural gas compressed by the high-pressure fuel supply system to the high-pressure fuel supply system.

Unlike the second embodiment, natural gas that has passed through the first compressor 110 and the second compressor 210 and then sent to the second compander 510 is expanded by the second expansion unit 512 Liquid separator 420 is not sent directly to the third compander 520, but is first sent to the third gas-liquid separator 420. The liquid sent to the third gas-liquid separator (420) after passing through the second expansion portion (512) is separated from the liquefied natural gas and the natural gas.

The liquefied natural gas separated by the third gas-liquid separator 420 passes through the sixth valve 720 and is sent to the second heat exchanger 310 to be used as a refrigerant. After passing through the sixth valve 720, The liquefied natural gas used as the refrigerant in the second heat exchanger 310 is partly or wholly vaporized so that the fluid sent from the third expansion part 522 to the second heat exchanger 310 flows into the second heat exchanger 310 And then sent to a line to be sent to the third compression section 521.

The natural gas separated by the third gas-liquid separator (420) is sent to the third expansion portion (522) of the third compander (520). The fluid once expanded by the third expansion part 522 after being separated by the third gas-liquid separator 420 is sent to the second heat exchanger 310 and used as a refrigerant.

Meanwhile, the evaporated gas generated in the storage tank 10 flows from the third compander 520 to the second heat exchanger 310 after passing through the second valve 20, as in the second embodiment. Is sent on the line to be sent.

The fluid separated by the third gas-liquid separator 420, passed through the third expansion part 522, and then sent to the second heat exchanger 310, is evaporated from the storage tank 10 as in the second embodiment Gas is heat-exchanged with natural gas as a refrigerant in the second heat exchanger 310, and then part or all of the gas is vaporized. The partially or fully vaporized fluid is sent from the third gas-liquid separator 420 to the second heat exchanger 310 and integrated with the fluid used as the refrigerant so that the third compressed portion 521 of the third compander 520, Lt; / RTI >

The fluid compressed by the third compressing section 521 is cooled by the fourth cooler 220 and then sent to the second compander 510 so as to be supplied to the second compressing section 511, Lt; / RTI > The fluid compressed by the second compression section 511 is cooled by the fifth cooler 230 and then sent again to the first compressor 110 in the same manner as in the second embodiment so that the above- .

The natural gas that has passed through the first compressor 110 and the second cooler 210 and then branched and passed through the third compressor 120 and the seventh cooler 240 is sent to the second heat exchanger 310, A liquefied natural gas expanded by the second expansion portion 512 and separated by the third gas-liquid separator 420; A fluid that is expanded by the second expansion portion 512 and separated by the third gas-liquid separator 420 and then once again expanded by the third expansion portion 522; And the evaporation gas discharged from the storage tank 10, and then expanded by the expansion means 600. [

The liquid, which has passed through the second heat exchanger 310 and the expansion means 600 and partially or completely liquefied, is separated from the liquid phase and the gas phase by the second gas-liquid separator 410 as in the second embodiment. The liquefied natural gas separated by the second gas-liquid separator 410 is sent to the storage tank 10 after passing through the fifth valve 30 as in the second embodiment and is sent to the second gas-liquid separator 410 After passing through the fourth valve 710, the natural gas separated by the natural gas is sent to the second heat exchanger 310 together with the fluid that has passed through the third expansion part 522, Is used.

4 is a schematic view showing a ship including a storage tank according to a fourth preferred embodiment of the present invention.

The ship including the storage tank of the fourth embodiment shown in Fig. 4 is different from the ship including the storage tank of the third embodiment shown in Fig. 3 in that the third heat exchanger 320, the fourth compressor 130, There is a difference in that it further includes the eighth cooler 250, and the difference will be mainly described below. A detailed description of the same components as those of the ship including the storage tank of the third embodiment described above will be omitted.

4, the vessel including the storage tank according to the present embodiment includes a first heat exchanger 305, a first gas-liquid separator 405, a first compander 500, The first compressor 110, the second compressor 210, the second compressor 115, the third cooler 215, the third compressor 120, the first condenser 110, the second condenser 115, A third compressor 420, a third compressor 420, a third compressor 420, a third compressor 420, a sixth valve 420, a third compressor 420, a third compressor 420, Liquid separator 410, a fourth valve 710, a fifth valve 30, a fourth cooler 220, a fifth cooler 230, and a second valve 30.

However, unlike the third embodiment, the vessel including the storage tank of the present embodiment is installed between the second expansion portion 512 and the third gas-liquid separator 420 so as to pass through the second expansion portion 512 A third heat exchanger 320 for self-heat-exchanging and liquefying natural gas; A fourth compressor (130) for compressing the fluid that has passed through the third heat exchanger (320) first; And an eighth cooler (250) that lowers the temperature of the fluid passing through the fourth compressor (130).

As in the third embodiment, it is preferable that a plurality of the storage tanks 10 installed in the ship of this embodiment are provided in parallel to each other in the longitudinal direction of the hull, and that the space inside the hull is easy to utilize. The evaporated gas generated in the storage tank 10 is sent to the third heat exchanger 310 from the third compander 520 to the third heat exchanger 310, 520 to the second heat exchanger 310 and the second heat exchanger 310 to cool the natural gas.

The first heat exchanger 305 of this embodiment uses the fluid discharged from the distillation tower 900 as a refrigerant to cool the natural gas supplied from the outside of the system, as in the third embodiment. The medium-hydrocarbon component is separated from the fluid cooled by the first heat exchanger 305 by the first gas-liquid separator 405 as in the third embodiment.

The natural gas supplied from the outside of the system to the first heat exchanger 305 may be a natural gas that has undergone a moisture drying process in a dryer as in the third embodiment.

The first gas-liquid separator 405 of this embodiment separates the heavy hydrocarbon component from the fluid cooled by the first heat exchanger 305 and sends the heavy hydrocarbon to the central portion of the distillation column 900 The fluid having the higher methane content removed from the heavy hydrocarbon component is sent to the first compander 500.

As in the third embodiment, the first compander 500 of the present embodiment is configured to expand the fluid sent from the first gas-liquid separator 405 after most of the heavy hydrocarbon components are separated by the first gas-liquid separator 405, 1 expanding portion (501); And a first compression unit (502) for compressing the fluid used as the refrigerant in the first heat exchanger (305). The first compression section 502 and the first expansion section 501 of the present embodiment are connected by an axis like in the third embodiment so that the energy of the first expansion section 501, The compression section 502 compresses the fluid.

As in the third embodiment, the first cooler 200 of this embodiment is compressed by the first compression section 502 and lowers the temperature of the fluid not only in pressure but also in temperature.

The distillation column 900 of the present embodiment separates the medium hydrocarbon separated from the first gas-liquid separator 405 and the fluid sent from the first expanding section 501 by the component in the same manner as the third embodiment and the condensate stores the condensate And the purified natural gas is sent to the first heat exchanger 305 so that the rate of methane is higher.

The distillation tower 900 of this embodiment may further include a reboiler 910 similar to the third embodiment and the reboiler 910 may be installed separately from the distillation tower 900.

The vessel including the storage tank of this embodiment includes, as in the third embodiment, a sixth cooler 205 for cooling the condensate discharged from the distillation tower 900; And a third valve 705 for controlling the flow rate and pressure of the condensate discharged from the distillation tower 900.

The first valve 700 of this embodiment is disposed on a line for sending heavy hydrocarbons from the first gas-liquid separator 405 to the distillation tower 900, as in the third embodiment, and regulates the flow rate and pressure of the heavy hydrocarbons .

The first compressor 110 of this embodiment compresses the fluid that has passed through the first cooler 200 after being compressed by the first compander 500 as in the third embodiment, (210) passes through the first compressor (110) and lowers the temperature of the natural gas not only in pressure but also in temperature, as in the third embodiment.

The second compressor 115 of the present embodiment compresses the natural gas that has passed through the first compressor 110 and the second compressor 210 to a pressure required by the engine installed on the ship, Of fuel supply system.

As in the third embodiment, the third cooler 215 of this embodiment is disposed downstream of the second compressor 115 to lower the temperature of the natural gas that has passed through the second compressor 115 and has increased in temperature as well as pressure .

The third compressor 120 of this embodiment further compresses some of the natural gas that has passed through the first compressor 110 and the second cooler 210 as in the third embodiment. The natural gas compressed by the first compressor 110 and the third compressor 120 of the present embodiment preferably has a pressure of about 50 bar or more so as to be in a supercritical state.

As in the third embodiment, the seventh cooler 240 of the present embodiment lowers the temperature of the natural gas which has passed through the third compressor 120 and has increased in temperature as well as pressure.

As in the third embodiment, the second compander 510 of the present embodiment includes a second expanding section 512 for expanding the fluid and a second compressing section 511 for compressing the fluid. The second expanding section 512 and the second compressing section 511 are axially connected to each other by the energy obtained by expanding the fluid by the second expanding section 512, (511) compresses the fluid.

Unlike the third embodiment, the second expansion unit 512 of the second compander 510 inflates a portion of the natural gas that has passed through the first compressor 110 and the second cooler 210, Liquid separator 420, but sends it to the third heat exchanger 320 first.

The second compressor 511 of the second compander 510 compresses the fluid sent from the third compander 520 and sends it to the first compressor 110 as in the third embodiment.

The third heat exchanger 320 of the present embodiment is configured such that the fluid that has passed through the second expansion portion 512 and the fourth compressor 130 and the eighth cooler 250 after passing through the third heat exchanger 320 Exchanges the fluid that has passed therethrough. That is, the third heat exchanger 320 uses the fluid that has passed through the second inflator as the refrigerant, passes through the fourth compressor 130 and the eighth cooler 250, and liquefies the fluid whose pressure is increased.

As shown in FIG. 5, when the pressure is low, even if the temperature of the natural gas is lowered, it may not be liquefied (X in FIG. 5) (Y in Fig. 5).

Therefore, the fluid that has passed through the second expansion portion 512 and the third heat exchanger 320 is compressed by the fourth compressor 130 and then sent to the third heat exchanger 320, and the second expansion portion 512) and self-heat exchanges with the fluid that has passed through the fourth compressor (130), the fluid whose pressure has been raised by the fourth compressor (130) is cooled and a part can be liquefied.

In the case where a sufficient amount of liquefied natural gas is not generated by the second expansion portion 512 of the second compander 510 solely for expansion and used as a refrigerant in the second heat exchanger 310, The third heat exchanger 320 and the fourth compressor 130 to increase the liquefaction amount of the natural gas used as the refrigerant.

The fourth compressor 130 of the present embodiment increases the pressure of the fluid that is first heat-exchanged as the refrigerant in the third heat exchanger 320 after passing through the second expansion portion 512.

The eighth cooler 250 of the present embodiment lowers the temperature of the fluid passing through the fourth compressor 130 as well as the pressure. The eighth cooler 250 can, for example, cool the fluid by exchanging the fluid with fresh water at about room temperature.

The third gas-liquid separator 420 of this embodiment separates the partially liquefied natural gas and the natural gas remaining in the gaseous state through the third heat exchanger 320 so that the liquefied natural gas To the second heat exchanger 310, and the natural gas is sent to the third compander 520 to be further expanded by the third expansion part 522.

The sixth valve 720 of the present embodiment is installed on a line for sending the liquefied natural gas separated by the third gas-liquid separator 420 to the second heat exchanger 310 as in the third embodiment, Adjust the flow and pressure of the gas.

As in the third embodiment, the third compander 520 of the present embodiment includes a third expanding section 522 for expanding the fluid and a third compressing section 521 for compressing the fluid. Similarly to the third embodiment, the third expanding section 522 and the third compressing section 521 are coupled by an axis so that the energy of the third expanding section 522 expanding the fluid causes the third compressing section 521 compress the fluid.

The third expansion part 522 of the third compander 520 can not be liquefied by the second expansion part 512 and the third heat exchanger and can return natural gas separated by the third gas- And then sent to the second heat exchanger 310. The fluid inflated by the third expansion portion 522 is used as a refrigerant for cooling the natural gas in the second heat exchanger 310 together with the evaporated gas discharged from the storage tank 10 as in the third embodiment do.

The third compression section 521 of the third compander 520 compresses the fluid used as the refrigerant in the second heat exchanger 310 and sends it to the second compander 510 as in the third embodiment .

The second heat exchanger 310 of the present embodiment is similar to the third embodiment in that the first compressor 110, the second cooler 210, the third compressor 210 and the seventh cooler 240, The gas is cooled by self-heat exchange with the refrigerant.

The second heat exchanger 310 of the present embodiment is different from the third embodiment in that the second expansion unit 512, the third heat exchanger 320, the fourth compressor 130 and the eighth cooler 250 The liquefied natural gas liquefied in the third heat exchanger 320 and separated by the third gas-liquid separator 420; After passing through the second expansion unit 512, the third heat exchanger 320, the fourth compressor 130 and the eighth cooler 250, they can not be liquefied in the third heat exchanger 320 and the third gas-liquid separator 420 ) And then passed through the third expansion portion (522); And evaporation gas discharged from the storage tank 10 are used as the refrigerant.

As in the third embodiment, the expansion means 600 of the present embodiment lowers the pressure of the fluid whose temperature is lowered by the heat exchange in the second heat exchanger 310, and the natural gas is introduced into the second heat exchanger 310 and the expansion means 600, the liquid is partly or entirely liquefied. The expansion means 600 may be an expansion valve or an expander.

The second gas-liquid separator 410 of this embodiment is disposed at the downstream end of the expansion means 600 and passes through the second heat exchanger 310 and the expansion means 600 to partially liquefy the liquefied natural gas The liquefied natural gas is sent to the storage tank 10, and the natural gas is supplied to the second heat exchanger 310 from the line- Lt; / RTI >

The fourth valve 710 of the present embodiment is installed on the line for sending natural gas between the third expansion portion 522 and the second heat exchanger 310 from the second gas-liquid separator 410 as in the third embodiment Thereby controlling the flow rate and pressure of the natural gas.

The fifth valve 30 of this embodiment is installed on a line for sending liquefied natural gas separated from the second gas-liquid separator 410 to the storage tank 10 as in the third embodiment, and the flow rate of the liquefied natural gas And pressure.

The fourth cooler 220 of the present embodiment is installed at the rear end of the third compression section 521 of the third compander 520 and passes through the third compression section 521 But the temperature also lowers the temperature of the raised fluid. The fluid that has passed through the third compression unit 521 and the fourth cooling unit 220 is sent to the second compander 510.

The fifth cooler 230 of the present embodiment is installed at the rear end of the second compression section 511 of the second compander 510 and passes through the second compression section 511 and is compressed But the temperature also lowers the temperature of the raised fluid. The fluid having passed through the second compression unit 511 and the fifth cooling unit 230 is sent to the first compressor 110.

The second valve 20 of the present embodiment is provided on the line for sending the vaporized gas in the storage tank 10 to the second heat exchanger 310 as in the third embodiment, 2 heat exchanger (310).

The flow of the fluid in this embodiment will be described as follows.

The natural gas supplied from the outside of the system is heat-exchanged with the refrigerant in the first heat exchanger 305 to be cooled and then sent to the first gas-liquid separator 405, and is supplied to the first gas-liquid separator 405 After the middle hydrocarbon component is separated and sent to the first expanding section 501 of the first compander 500 and the fluid expanded by the first expanding section 501 flows into the distillation column 900 ). The heavy hydrocarbons separated by the first gas-liquid separator 405 are sent to the central portion of the distillation column 900 after passing through the first valve 700, as in the third embodiment.

The fluid that has been subjected to fractional distillation by the distillation tower 900 and whose temperature is lowered from the top of the distillation tower 900 is sent to the first heat exchanger 305 to cool the natural gas supplied from the outside of the system And then sent to the first compression unit 502 of the first compander 500. [ The fluid sent to the first compression section 502 is expanded by the first compression section 502 and cooled by the first refrigerator 200 and then sent to the first compressor 110 as in the third embodiment . On the other hand, the condensate separated by the distillation tower 900 may be cooled by the sixth cooler 205 and then sent to the condensate storage tank via the third valve 705, as in the third embodiment.

The fluid that is expanded by the first compression section 502 and cooled by the first cooler 200 is branched to a low pressure fuel supply system in the same manner as the third embodiment, Compressed by the first cooler 110, cooled by the second cooler 210, and then branched again into two flows.

Natural gas, which is compressed by the first compressor 110, cooled by the second cooler 210, and then diverted into two flows, flows in the same manner as in the third embodiment, 3 cooler 215 and then to a high-pressure fuel supply system, and the other flow branches again into two flows.

After passing through the first compressor 110 and the second cooler 210, the natural gas that is not sent to the high-pressure fuel supply system but is diverted into two flows, as in the third embodiment, flows in the third compressor 120 and the seventh cooler 240 and then to the second heat exchanger 310 and the other stream is sent to the second compander 510. [

Also, as in the third embodiment, the ship including the storage tank of this embodiment uses the first compressor 110 used for liquefying natural gas in conjunction with the high-pressure fuel supply system, and the first compressor 110 A plurality of compressors and a plurality of coolers, which are additionally installed on the line for sending the natural gas compressed by the high-pressure fuel supply system to the high-pressure fuel supply system.

Unlike the third embodiment, natural gas that has passed through the first compressor 110 and the second compressor 210 and then sent to the second compander 510 is expanded by the second expansion unit 512 Liquid separator 420, but is sent to the third heat exchanger 320 first. The fluid sent to the third heat exchanger 320 after passing through the second expansion part 512 is heat-exchanged in the third heat exchanger 320 as the first refrigerant and then flows into the fourth compressor 130 and the eighth cooler 250 and then again exchanges heat with the fluid sent from the second expansion portion 512 to the third heat exchanger 320. The fluid that has undergone the second heat exchange in the third heat exchanger (320) after passing through the fourth compressor (130) and the eighth cooler (250) is sent to the third gas-liquid separator (420).

The liquid sent to the third gas-liquid separator 420 is separated from the liquefied natural gas and the natural gas and separated by the third gas-liquid separator 420 in the same manner as in the third embodiment, Likewise, after passing through the sixth valve 720, the natural gas is sent to the second heat exchanger 310 and used as a refrigerant, and the natural gas separated by the third gas-liquid separator 420, The refrigerant is sent to the third expansion part 522 of the compander 520 and expanded once again and then sent to the second heat exchanger 310 to be used as a refrigerant.

The evaporated gas generated in the storage tank 10 flows from the third compander 520 to the second heat exchanger 310 after passing through the second valve 20 as in the third embodiment. Is sent on the line to be sent.

The liquefied natural gas that has been separated by the third gas-liquid separator 420 and passed through the sixth valve 720 and the second heat exchanger 310 is partially or wholly vaporized as in the third embodiment, The fluid sent from the expansion portion 522 to the second heat exchanger 310 is sent to the third compression portion 521 after passing through the second heat exchanger 310.

The fluid separated by the third gas-liquid separator 420, passed through the third expansion portion 522, and then sent to the second heat exchanger 310, is evaporated from the storage tank 10 as in the third embodiment A part or all of the vaporized and partially vaporized fluid after heat exchange with the natural gas in the second heat exchanger 310 is supplied to the third gas-liquid separator 420 from the third gas-liquid separator 420 2 heat exchanger 310 to be combined with the fluid used as the refrigerant and sent to the third compression section 521 of the third compander 520. [

The fluid compressed by the third compressing section 521 is cooled by the fourth cooler 220 and then sent to the second compander 510 so as to be supplied to the second compressing section 511, Lt; / RTI > The fluid compressed by the second compression unit 511 is cooled by the fifth cooler 230 and then sent again to the first compressor 110 in the same manner as in the third embodiment so that the above- .

The natural gas that has passed through the first compressor 110 and the second cooler 210 and then branched and passed through the third compressor 120 and the seventh cooler 240 is subjected to the second heat exchange Liquid natural gas separated by the third gas-liquid separator 420; A fluid expanded by the third expanding portion 522; And the evaporation gas discharged from the storage tank 10, and then expanded by the expansion means 600. [

The fluid that has passed through the second heat exchanger 310 and the expansion means 600 and partially or fully liquefied is separated from the liquid phase and the gas phase by the second gas-liquid separator 410 as in the third embodiment. The liquefied natural gas separated by the second gas-liquid separator 410 is sent to the storage tank 10 after passing through the fifth valve 30 as in the third embodiment and is sent to the second gas-liquid separator 410 After passing through the fourth valve 710, the natural gas separated by the natural gas is sent to the second heat exchanger 310 together with the fluid that has passed through the third expansion portion 522, Is used.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit and scope of the invention. It is.

10: Storage tank
20, 30, 700, 705, 710, 720: valve
110, 115, 120, 130: compressor
200, 205, 210, 215, 220, 230, 240, 250:
305, 310, 320: heat exchanger 405, 410, 420: gas-liquid separator
500, 510, 520: Compander 502, 511, 521:
501, 512, 522: expanding part 600: expansion means
900: Distillation tower 910: Reboiler

Claims (25)

1. A ship comprising a storage tank,
A first heat exchanger that cools the natural gas supplied from the outside of the system by exchanging heat with the refrigerant;
A first gas-liquid separator that passes through the first heat exchanger and separates heavy hydrocarbons from the cooled fluid;
A first compander for compressing the fluid heat-exchanged as a refrigerant in the first heat exchanger or for expanding the fluid in which the heavy hydrocarbons are separated by the first gas-liquid separator;
A first cooler for cooling the fluid compressed by the first compander;
A distillation tower for separating the fluid passing through the first gas-liquid separator;
A first valve for regulating the flow rate and pressure of the medium hydrocarbon sent from the first gas-liquid separator to the distillation column;
A first compressor for compressing the fluid having passed through the first cooler after being compressed by the first compander;
A second compander and a third compander for expanding or compressing the fluid;
A second cooler for cooling the natural gas compressed by the first compressor;
A second heat exchanger for cooling the natural gas by self-heat exchange;
Expansion means for expanding the fluid that has passed through said second heat exchanger;
A fourth cooler for cooling the fluid passing through the second compander;
A fifth cooler for cooling the fluid passing through the third compander; And
And a second valve installed on a line for sending the evaporated gas in the storage tank to the second heat exchanger to regulate the flow rate and pressure of the evaporated gas sent from the storage tank to the second heat exchanger,
The first heat exchanger is configured to cool the natural gas supplied from the outside of the system using the fluid discharged from the upper portion of the distillation tower as a refrigerant,
A portion of the fluid cooled by the first cooler after being compressed by the first compander is diverted at the front end of the first compressor and sent to the low pressure fuel supply system,
Said second heat exchanger comprising: a fluid which is split after passing through said first compressor and said second cooler and expanded by at least one of said second compander and said third compander; And evaporation gas discharged from the storage tank as a refrigerant to cool another natural gas branched after passing through the first compressor and the second cooler. The method according to claim 1,
Wherein the natural gas supplied to the first heat exchanger is a natural gas that has undergone a moisture drying process in a dryer. The method according to claim 1,
The heavy hydrocarbons separated from the first gas-liquid separator are sent to the central portion of the distillation column,
Wherein the fluid expanded by the first compander is sent to the top of the distillation column. The method according to claim 1,
Wherein the first compander comprises:
A first expansion unit for expanding the fluid sent from the first gas-liquid separator after the heavy hydrocarbons are separated by the first gas-liquid separator; And
And a first compression unit for compressing a fluid used as a refrigerant in the first heat exchanger,
Wherein the first compression portion and the first expansion portion are connected in an axial direction so that the first expansion portion compresses the fluid by the energy obtained by expanding the fluid. The method according to claim 1,
The distillation column separates the condensate from the fluid sent to the distillation column,
A sixth cooler for cooling the condensate discharged from the distillation column; And
Further comprising a third valve for adjusting the flow rate and pressure of the condensate discharged from the distillation column. The method according to claim 1,
Wherein the distillation tower further comprises a reboiler at the bottom. The method according to claim 1,
Further comprising a reboiler installed separately from the distillation column. The method according to claim 1,
A second compressor for compressing the natural gas having passed through the first compressor and the second cooler; And
A third cooler for cooling the natural gas compressed by the second compressor;
Further comprising:
Wherein the natural gas having passed through the first compressor, the second cooler, the second compressor, and the third cooler is sent to a high-pressure fuel supply system. The method according to claim 1,
Wherein the natural gas having passed through the first compressor is in a supercritical fluid state. The method according to claim 1,
The second compander includes a second expanding portion for expanding the fluid and a second compressing portion for compressing the fluid,
The third compander includes a third expanding portion for expanding the fluid and a third compressing portion for compressing the fluid,
The second expanding portion is axially connected to the second compressing portion, the second expanding portion compresses the fluid by the energy obtained by expanding the fluid,
The third expanding portion is axially connected to the third compressing portion so that the third expanding portion compresses the fluid by the energy obtained by expanding the fluid,
The fluid expanded by at least one of the second expansion portion and the third expansion portion is returned to the first compressor after the pressure is restored by at least one of the second compression portion and the third compression portion, A vessel including a storage tank. The method according to claim 1,
Wherein the expansion means is an expansion valve or inflator. The method according to claim 1,
A third compressor for additionally compressing the natural gas compressed by the first compressor;
A seventh cooler for lowering the temperature of the natural gas passing through the third compressor;
A second gas-liquid separator provided at a downstream end of the expansion means for separating liquefied natural gas from natural gas in a gaseous state;
A fourth valve for controlling the flow rate and pressure of the natural gas separated by the second gas-liquid separator; And
And a fifth valve for controlling the flow rate and pressure of the liquefied natural gas separated by the second gas-liquid separator and sent to the storage tank,
The natural gas that has passed through the first compressor, the second cooler, the third compressor, and the seventh cooler is cooled in the second heat exchanger,
Wherein the gaseous natural gas separated by the second gas-liquid separator is sent on a line through which fluid is sent from the third compander to the second heat exchanger. The method of claim 12,
Wherein the natural gas having passed through the first compressor and the third compressor is in a supercritical fluid state. The method of claim 12,
A third gas-liquid separator that passes through the second compander and separates a part of liquefied natural gas and natural gas remaining in a gaseous state; And
And a sixth valve for adjusting the flow rate and pressure of the liquefied natural gas separated by the third gas-liquid separator and sent to the second heat exchanger,
The gaseous natural gas separated by the third gas-liquid separator is sent to the third compander,
Wherein the second heat exchanger comprises: liquefied natural gas separated by the third gas-liquid separator and then passed through the sixth valve; And a fluid which has been separated by the third gas-liquid separator and has passed through the third compander, is used as a refrigerant. 15. The method of claim 14,
A third heat exchanger for self-heat-exchanging liquefied natural gas passing through the second compander;
A fourth compressor for compressing the fluid passing through the third heat exchanger; And
And an eighth cooler for lowering the temperature of the fluid passing through the fourth compressor,
Wherein the third heat exchanger uses the fluid sent from the second compander as a refrigerant to cool the fluid that has passed through the third heat exchanger, the fourth compressor, and the eighth cooler after being sent from the second compander To the third gas-liquid separator. A first gas-liquid separator for separating heavy hydrocarbons from the natural gas having passed through the first heat exchanger, a second gas-liquid separator for separating the heavy hydrocarbons from the natural gas, A first compression section of a first compander for compressing a fluid used as a refrigerant in the first heat exchanger, a first expansion section of a first compander for expanding the fluid, 1 distillation system comprising a condenser and a distillation column separating the condensate from the medium hydrocarbons separated by the first gas-liquid separator and the fluid expanded by the first expansion part;
A first compressor for compressing natural gas supplied from the outside, a second expander for expanding the fluid passing through the first compressor, a third expander for expanding the fluid further expanded by the second expander, A third expansion unit of the third compander, a second heat exchanger that uses the fluid expanded by the third expansion unit as a refrigerant, a third heat exchanger that compresses the fluid used as the refrigerant in the second heat exchanger, And a second compression section of the second compander which compresses the fluid compressed by the third compression section again and sends it to the first compressor;
A fuel supply system for supplying a part of the natural gas supplied from the outside to the fuel of the engine;
And a second valve disposed on a line that directs the evaporated gas in the storage tank to the second heat exchanger to regulate the flow rate and pressure of the evaporated gas sent from the storage tank to the second heat exchanger, system; And
The second heat exchanger for cooling the natural gas that has passed through the first compressor by using the first compressor, the refrigerant supplied by the refrigerant system, and the evaporation gas supplied from the storage tank, and the second heat exchanger A liquefaction system including an expansion means for expanding a fluid,
Wherein the first heat exchanger uses the fluid discharged from the upper portion of the distillation tower as a refrigerant,
The refrigerant system is an open loop,
Wherein the first compressor is used in conjunction with the fuel supply system. 18. The method of claim 16,
The fuel supply system includes:
Further comprising a second compressor for additionally compressing and delivering natural gas compressed by said first compressor to said fuel supply system. 18. The method of claim 17,
A part of the natural gas supplied from the outside is branched at the front end of the first compressor and sent to the low pressure fuel supply system,
Wherein the natural gas compressed by the first compressor and the second compressor is sent to a high pressure fuel supply system. 18. The method of claim 16,
In the liquefaction system,
Further comprising a second gas-liquid separator for separating liquefied natural gas that has passed through the second heat exchanger and the expansion means and natural gas remaining in a gaseous state,
The liquefied natural gas separated by the second gas-liquid separator is sent to the storage tank,
Wherein the natural gas separated by the second gas-liquid separator is sent to the refrigerant system. 18. The method of claim 16,
In the refrigerant system,
Further comprising a third gas-liquid separator for separating the liquefied natural gas liquefied by the second expansion part and the natural gas remaining in the gaseous state,
The liquefied natural gas separated by the third gas-liquid separator is sent to the second heat exchanger and used as a refrigerant,
Wherein the natural gas separated by the third gas-liquid separator is sent to the third expansion unit. 18. The method of claim 16,
In the refrigerant system,
A third heat exchanger for liquefying the fluid expanded by the second expansion part and sending it to the third gas-liquid separator; And
And a fourth compressor for compressing the fluid that has passed through the third heat exchanger,
Wherein the third heat exchanger includes a storage tank that uses the fluid that has passed through the second expanding portion as a refrigerant and that cools the fluid that has passed through the third expanding portion and passed through the third heat exchanger and the fourth compressor Ship. The natural gas supplied from the outside of the system is cooled by heat exchange with the fluid discharged from the distillation tower,
Separating the heavy hydrocarbons from the fluid cooled by the heat exchange,
The heavier hydrocarbons expand the separated fluid and send it to the top of the distillation tower,
The separated heavy hydrocarbons are sent to the center of the distillation column,
The fluid discharged from the top of the distillation tower after the condensate is separated by the distillation tower is used as a refrigerant for cooling the natural gas supplied from the outside of the system,
The fluid used as the refrigerant for cooling the natural gas supplied from the outside of the system is compressed using the energy released when the heavy hydrocarbon expands the separated fluid,
A part of the compressed and cooled fluid which has been used as the refrigerant of the heat exchange is sent to the low pressure fuel supply system, the other part is compressed and cooled again,
Branching said re-compacted and cooled fluid into two streams,
Of the two branched flows, one flow of fluid is further compressed and cooled and sent to the high-pressure fuel supply system, and the fluid of another flow (hereinafter referred to as a flow) is branched again into two flows,
(Hereinafter, referred to as 'c') is expanded by expanding one of the branched a flows (hereinafter referred to as 'b flow') and using the expanded b flow and evaporation gas as refrigerant, Quot; flow "),
The c-flow that is heat-exchanged with the b-flow as the refrigerant is expanded and partially or fully liquefied,
Wherein the b stream that has been expanded and exchanged with the c stream is compressed by the energy released when the b stream is expanded. 23. The method of claim 22,
The c-flow heat exchanged with the b-flow as a refrigerant is expanded and partly or wholly liquefied, the liquid phase and the gaseous phase are separated, the separated liquefied natural gas is sent to a storage tank, And again exchanging heat with the refrigerant to cool the c stream. 23. The method of claim 22,
Wherein the liquid phase and the gaseous phase are separated so that the separated liquefied natural gas is heat-exchanged as a refrigerant for cooling the c-flow after the compression and cooling, and the separated natural gas is further expanded so that the c-flow And heat exchanged as a cooling refrigerant. 23. The method of claim 22,
Wherein the expanded b-stream is heat-exchanged as a refrigerant that is compressed and cooled after being heat-exchanged as a refrigerant (hereinafter referred to as 'd-flow') and self-heat-exchanged with the d-flow, followed by cooling the c-flow.

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