KR101714676B1 - 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 natural gas by heat exchange with the refrigerant; A first gas-liquid separator for separating heavy hydrocarbons from the fluid cooled by the first heat exchanger; A first expansion unit for expanding the fluid into which the heavy hydrocarbons have been separated by the first gas-liquid separator; A first compression unit for compressing a fluid used as a refrigerant in the first heat exchanger; A distillation column for distilling the medium hydrocarbon separated by the first gas-liquid separator and the fluid expanded by the first expansion unit; A second heat exchanger for cooling a part of the refrigerant flow branched by the first compression unit (hereinafter referred to as "x-flow") by heat exchange with the refrigerant; Expansion means for expanding the fluid cooled by said second heat exchanger; 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 second expanding unit for expanding a flow of the fluid compressed by the first compressing unit except for the 'x flow' (hereinafter referred to as 'y flow'); And a second compression unit for compressing the fluid used as the refrigerant in the second heat exchanger after being expanded by the second expansion unit, wherein the first compression unit and the first expansion unit are connected to the first compressor The second compression section and the second expansion section constitute a second compander and the fluid discharged from the distillation column is supplied to the first compression section after being used as a refrigerant in the first heat exchanger, 2 heat exchanger includes: a fluid expanded by the second expanding portion; And the natural gas separated by the second gas-liquid separator are used as a refrigerant to cool the 'x-flow'.

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.

The present invention relates to a liquefaction system for liquefied natural gas, which uses liquefied natural gas itself as a refrigerant without using a separate refrigerant system and returns liquefied natural gas to a storage tank, And to provide a vessel including a storage tank that connects a system for liquefying natural gas with a system for supplying fuel to the engine.

Also, in the process of separating a part of liquefied fluid into liquefied natural gas and natural gas, the concentration of nitrogen contained in the natural gas becomes high. After the liquefied natural gas having a high concentration of nitrogen is partially liquefied, When the process of separating the gas is repeated, the concentration of nitrogen contained in the natural gas is continuously increased.

The higher the concentration of nitrogen in the natural gas, the lower the overall liquefaction efficiency.

It is an object of the present invention to provide a vessel including a storage tank that uses natural gas separated from a part of liquefied fluid as fuel of an engine without sending it back to a liquefaction cycle.

According to an aspect of the present invention, there is provided a gas turbine comprising: a first heat exchanger for cooling natural gas by heat exchange with a refrigerant; A first gas-liquid separator for separating heavy hydrocarbons from the fluid cooled by the first heat exchanger; A first expansion unit for expanding the fluid into which the heavy hydrocarbons have been separated by the first gas-liquid separator; A first compression unit for compressing a fluid used as a refrigerant in the first heat exchanger; A distillation column for distilling the medium hydrocarbon separated by the first gas-liquid separator and the fluid expanded by the first expansion unit; A second heat exchanger for cooling a part of the refrigerant flow branched by the first compression unit (hereinafter referred to as "x-flow") by heat exchange with the refrigerant; Expansion means for expanding the fluid cooled by said second heat exchanger; 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 second expanding unit for expanding a flow of the fluid compressed by the first compressing unit except for the 'x flow' (hereinafter referred to as 'y flow'); And a second compression unit for compressing the fluid used as the refrigerant in the second heat exchanger after being expanded by the second expansion unit, wherein the first compression unit and the first expansion unit are connected to the first compressor The second compression section and the second expansion section constitute a second compander and the fluid discharged from the distillation column is supplied to the first compression section after being used as a refrigerant in the first heat exchanger, 2 heat exchanger includes: a fluid expanded by the second expanding portion; And a natural gas separated by the second gas-liquid separator as a refrigerant to cool the 'x-flow'.
The fluid having passed through the second compression section may be merged into a line between the first compression section and the second heat exchanger.
The evaporated gas discharged from the storage tank may be combined with the evaporated gas separated by the second gas-liquid separator and used as the refrigerant of the second heat exchanger.
The ship including the storage tank may further include a first compressor for compressing the fluid compressed by the first compressing unit, wherein the fluid compressed by the first compressing unit and the first compressor is compressed by the x Flow and the y-flow, and the fluid having passed through the second compression section may be merged into the line between the first compression section and the first compressor.
The natural gas used as the refrigerant in the second heat exchanger after being separated by the second gas-liquid separator may be sent to the fuel supply system.
Wherein the vessel including the storage tank further comprises: a third expanding unit for once again expanding the fluid expanded by the second expanding unit; And a third compression unit for compressing a fluid used as a refrigerant in the second heat exchanger after being expanded by the third expansion unit, and the third compression unit and the third expansion unit may further include a third expansion unit Wherein the fluid compressed by the third compression section is compressed by the second compression section, and the second heat exchanger comprises: a fluid expanded by the third expansion section; And the natural gas separated by the second gas-liquid separator can be used as a refrigerant.
Wherein the vessel including the storage tank is installed on a line that is separated by the second gas-liquid separator and then sent to the fuel supply system as natural gas used as a refrigerant in the second heat exchanger, And may further include a second compressor.
The distillation column may separate the condensate from the fluid sent to the distillation column, and the vessel including the storage tank may further include a sixth cooler for cooling the condensate discharged from the distillation column.
The fluid cooled by the second heat exchanger may be in a supercritical state.
The ship including the storage tank may further include a third compressor for additionally compressing the fluid compressed by the first compressor, and the fluid compressed by the first compressor and the third compressor may further include: 2 heat exchanger and can be cooled by heat exchange with the refrigerant.
The vessel including the storage tank may further include a third gas-liquid separator for separating natural gas remaining in a gaseous state and a part of liquefied natural gas passing through the second expansion portion, Wherein the natural gas separated by the third gas-liquid separator is sent to the third expansion unit, and the second heat exchanger includes: liquefied natural gas separated by the third gas-liquid separator; A fluid inflated by the third inflation section; And the natural gas separated by the second gas-liquid separator can be used as a refrigerant.
The ship including the storage tank may include: a third heat exchanger using the fluid expanded by the second expansion unit as a refrigerant; And a fourth compressor for compressing the fluid used as the refrigerant in the third heat exchanger after being expanded by the second expander, and the fluid compressed by the fourth compressor is further compressed by the third compressor The fluid expanded by the second expansion part in the heat exchanger may be cooled by heat exchange with the refrigerant and then sent to the third gas-liquid separator.
According to another aspect of the present invention, there is provided a distillation system for separating condensed and heavy hydrocarbon components contained in natural gas; A refrigerant system for cooling natural gas from which condensate and heavy hydrocarbons are separated by the distillation system; A liquefaction system for liquefying natural gas using natural gas cooled by the refrigerant system and evaporation gas supplied from a storage tank as a refrigerant; An evaporation gas supply system for supplying evaporation gas discharged from the storage tank to the liquefaction system; And a fuel supply system for supplying natural gas used as refrigerant in the liquefaction system to the fuel of the engine, wherein the refrigerant system is an open loop.
The distillation system comprises: a first heat exchanger for cooling natural gas; And a first compander including a first expansion portion and a first compression portion, wherein the natural gas cooled by the first heat exchanger can be expanded by the first expansion portion, and condensed and heavy hydrocarbons The separated natural gas may be used as a refrigerant for cooling the natural gas in the first heat exchanger, and then compressed by the first compressing unit.
The refrigerant system includes a third heat exchanger for self-heat-exchanging natural gas supplied from the distillation system to cool the natural gas; And a fourth compressor for compressing natural gas used as a refrigerant in the third heat exchanger and then returning the natural gas to the third heat exchanger, wherein the third heat exchanger further comprises: a natural gas Can be cooled by heat-exchanging natural gas supplied from the distillation system with a refrigerant.
The natural gas supplied from the refrigerant system and used as the refrigerant in the liquefaction system can be combined with the natural gas supplied from the distillation system.
According to another aspect of the present invention, there is provided a method of separating a hydrocarbon from a fluid that is cooled by 1) cooling a natural gas by heat exchange with a fluid discharged from a distillation tower, 2) performing heat exchange in the step 1) , 3) expanding the fluid in which the heavy hydrocarbons have been separated in the step 2), and then sending the expanded hydrocarbon to the top of the distillation tower, 4) sending the heavy hydrocarbon separated in the step 2) to the center part of the distillation tower, and 5) The fluid discharged from the top of the distillation tower after being separated is used as a refrigerant for cooling the natural gas in the step 1), 6) a fluid used as a refrigerant for cooling the natural gas in the step 1) 7) compressing the fluid compressed in step 6) into two streams, and 8) compressing the fluid A flow (hereinafter referred to as 'a flow') is expanded, and 9) the 'a flow' expanded in the step 8) is used as a refrigerant, and in the step 7) B) flow is cooled by heat exchange with another branched flow (hereinafter referred to as "b-flow"), 10) the b-flow cooled in step 9) is expanded and partly liquefied, and 11) The liquefied natural gas is partially separated from the liquefied natural gas, and the liquefied natural gas is partially separated from the liquefied natural gas, and the natural gas separated in the step 11) A) flow after being used as the refrigerant of the heat exchange for cooling the 'b-flow' in the step 9), the 'a-flow' is obtained by the energy released when the 'a-flow' Compressing, compressing, and so on.
In the step 8), the 'a flow' may be expanded after being further compressed.
8-4) The 'a flow' expanded in the step 8) is a process of separating the liquefied natural gas from the gaseous natural gas and separating the natural gas in the gaseous state separated from the 'a flow' Gas is expanded again and is used as a refrigerant for cooling by heat-exchanging the 'b-flow' in the step 9), and the liquefied natural gas separated from the 'a-flow' in the step 8-4) 9) may be used as a refrigerant for cooling by heat-exchanging the 'b-flow'.
8-1) The 'a flow' expanded in the step 8) is used as a refrigerant in the third heat exchanger, and 8-2) the 'a' used as the refrigerant of the third heat exchanger in the step 8-1) The flow 'is compressed, and 8-3) the' a flow 'compressed in the 8-2) step is the same as the' a flow 'in the step 8-1) by the third heat exchanger And the fluid cooled by the third heat exchanger in the step 8-3) is separated from the liquefied natural gas and the gaseous natural gas in the step 8-4).

According to the present invention, since the liquefied natural gas itself is used as a refrigerant without using a separate refrigerant system, 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.

The present invention relates to a natural gas liquefaction system in conjunction with an engine fuel supply system, so that natural gas at a pressure required by an engine can be supplied as fuel without separately installing a compressor for supplying fuel to the engine.

In addition, since the present invention can prevent the concentration of nitrogen contained in natural gas from increasing, the liquefaction efficiency can be increased.

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 a storage tank of the present embodiment includes a first heat exchanger 305 for cooling natural gas by heat exchange with a refrigerant; 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 compander 510 and a third compander 520 for expanding or compressing the fluid; A second heat exchanger (310) for cooling natural gas having passed through the first compressor (110) and the second cooler (210) by heat exchange with the refrigerant; Expansion means (600) for expanding the fluid having passed through the second heat exchanger (310); 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 second valve (710) for regulating the flow rate and pressure of the gaseous natural gas separated by the second gas-liquid separator (410); A third valve 30 for regulating the flow rate and pressure of the liquefied natural gas separated by the second gas-liquid separator 410 and sent to the storage tank 10; A third cooler 220 for cooling the fluid passing through the third compander 520; A fourth cooler 230 for cooling the fluid passing through the second compander 510; A second compressor (115) for compressing natural gas used as a refrigerant in the second heat exchanger (310) after being separated by the second gas-liquid separator (410) and sending it to the fuel supply system; And a fifth cooler 215 for cooling the fluid passing through the second compressor 115.

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 to the second gas-liquid separator 410 via the second gas-liquid separator 410, Is used as a refrigerant in the second heat exchanger (310) together with the natural gas sent to the heat exchanger (310). The liquefied natural gas separated by the second gas-liquid separator 410 is sent to the storage tank 10 through the third valve 30.

The first heat exchanger 305 of this embodiment exchanges natural gas 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. 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 crude oil drilled in the sea bed is subjected to various pretreatment processes and then liquefied to be liquefied natural gas. Natural gas supplied to the first heat exchanger 305 is subjected to a moisture drying process in a dryer May be natural gas.

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 fourth 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 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 expansion portion 512 and the third expansion portion 522 is used as a refrigerant for cooling the natural gas in the second heat exchanger 310. 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 The natural gas separated by the second gas-liquid separator 410, and the evaporated gas discharged from the storage tank 10 are cooled by the self-heat exchange. 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 this embodiment uses natural gas separated by the second gas-liquid separator 410 as a refrigerant for cooling natural gas in the second heat exchanger 310, It is possible to prevent the concentration of nitrogen contained in the natural gas from increasing.

In addition, since the ship including the storage tank of the present embodiment uses the evaporated gas generated in the storage tank 10 as the refrigerant for cooling the natural gas in the second heat exchanger 310, the energy of the evaporated gas is not wasted It is possible to lower the internal pressure of the storage tank 10 by treating the evaporation gas and improve the liquefaction efficiency in the second heat exchanger 310.

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 liquefied while passing through the second heat exchanger 310 and the expansion means 600, and the expansion means 600 can 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 liquefied natural gas is sent to the storage tank 10 and the natural gas is sent to the second heat exchanger 310 by separating the natural gas.

The second valve 710 of the present embodiment is installed on a line for sending the natural gas separated by the second gas-liquid separator 410 to the second heat exchanger 310 to regulate the flow rate and the pressure of the natural gas.

The third 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 third 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 having passed through the third compression unit 521 and the third cooling unit 220 is sent to the second compander 510.

The fourth 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 pass through the second compressing section 511 and not only the pressure but also the temperature . The fluid that has passed through the second compression unit 511 and the fourth cooling unit 230 is sent to the first compressor 110.

The second compressor 115 of this embodiment compresses the natural gas used as the refrigerant in the second heat exchanger 310 after passing through the second valve 710 after being separated by the second gas-liquid separator 410, To the supply system. The second compressor 115 compresses the compressed natural gas when the value of the sensor that measures the pressure inside the storage tank 10 is lower than a predetermined value so that the pressure inside the storage tank 10 can be maintained at a predetermined value. The flow rate of the gas is lowered, and when the flow rate is higher than the predetermined value, the flow rate of the natural gas to be compressed can be increased.

The fifth cooler 215 of the present embodiment is installed at the downstream end of the second compressor 115 to lower the temperature of the fluid passing through the second compressor 115 as well as the pressure.

In this embodiment, one compressor 115 and one cooler 215 on the line for sending natural gas to the fuel supply system are separated by the second gas-liquid separator 410 and then the second heat exchanger 310 The natural gas used as the refrigerant is supplied as the fuel of the engine through the one-stage compression process. However, the ship including the storage tank of the present embodiment has a plurality of compressors and a plurality of coolers The natural gas may be subjected to a multistage compression process according to the pressure required by the engine.

The third cooler 220, the fourth cooler 230, and the fifth cooler 215 of this embodiment can cool the fluid by, for example, heat-exchanging the fluid with fresh water at about room temperature.

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

The natural gas 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 hydrocarbon component is separated by the first gas-liquid separator 405, 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 whose temperature is lowered from the upper portion of the distillation tower 900 by fractional distillation by the distillation tower 900 is used as a refrigerant for cooling the natural gas sent to the first heat exchanger 305, 500). ≪ / RTI > The fluid sent to the first compression unit 502 is compressed by the first compression unit 502, cooled by the first refrigerator 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 fourth valve 705.

The fluid compressed by the first compressing section 502 and cooled by the first cooler 200 is compressed by the first compressor 110 and cooled by the second cooler 210 and then branched into two flows .

One of the two streams of natural gas that has branched off after passing through the first compressor 110 and the second cooler 210 is sent to the second heat exchanger 310 and 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.

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 fluid expanded by the second expansion portion 512 and the third expansion portion 522 flows in the second heat exchanger 310 through the first compressor 110 and the second compressor 210, And then sent to the third compression section 521 of the third compander 520 to be compressed.

The fluid compressed by the third compression section 521 is cooled by the third cooler 220 and then sent again to the second compander 510 and compressed again by the second compression section 511 . The fluid compressed by the second compressing unit 511 is cooled by the fourth cooler 230 and then sent again to the first compressor 110 so that the above-described series of steps is performed again.

That is, the fluid used as the refrigerant in the second heat exchanger 310 after being expanded by the second expansion part 512 and the third expansion part 522 flows through the second compression part 511 and the third compression part 521 and is returned to the first compressor 110 after the pressure has been restored by the second expanding section 512 and the third expanding section 522 to the lowered 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, , The natural gas separated by the second gas-liquid separator (410), and the evaporated gas discharged from the storage tank (10), and then expanded by the expansion means (600). Liquid having passed through the second heat exchanger 310 and the expansion means 600 and partially liquefied is sent to the second gas-liquid separator 410 so that it can not be liquefied with the liquefied natural gas by the second gas- The remaining natural gas is separated.

The liquefied natural gas separated by the second gas-liquid separator 410 is sent to the storage tank 10 after passing through the third valve 30 and the natural gas separated by the second gas- Passes through the valve 710, is sent to the second heat exchanger 310, is used as the refrigerant, and then is sent to the second compressor 115.

The fluid that has been used as the refrigerant in the second heat exchanger 310 and then sent to the second compressor 115 is compressed by the second compressor 115 and cooled by the fifth cooler 215 and then sent to the fuel supply system , And is used as fuel for the engine.

On the other hand, the evaporated gas generated in the storage tank 10 is discharged from the second gas-liquid separator 410 to the second heat exchanger 310 via the line- Lt; / RTI >

The evaporated gas sent from the storage tank 10 to the line through which the natural gas is sent from the second gas-liquid separator 410 to the second heat exchanger 310 is mixed with the natural gas separated by the second gas- Exchanged as a refrigerant in the second heat exchanger 310 and then sent to the fuel supply system through the second compressor 115 and the fifth cooler 215. [

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 and the seventh cooler 240 are further provided There are differences in that they include, and the differences are 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, The first compressor 110, the second compressor 210, the second compander 510, the third compander 520, the second heat exchanger (not shown) The third valve 30, the third cooler 220, the fourth cooler 230, the second compressor 308, the third compressor 309, the third compressor 309, the third compressor 309, the expansion unit 600, the second gas-liquid separator 410, the second valve 710, (115), and a fifth cooler (215).

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; And a seventh cooler 240 for lowering the temperature of the natural gas that has passed through the third compressor 120.

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 natural gas separated by the second gas-liquid separator 410 is sent to a line to be sent to the second heat exchanger 310, and the second gas- Is used as a refrigerant in the second heat exchanger (310) together with the natural gas sent from the separator (410) to the second heat exchanger (310). The liquefied natural gas separated by the second gas-liquid separator 410 is sent to the storage tank 10 through the third valve 30 as in the first embodiment.

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, 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.

The natural gas supplied to the first heat exchanger 305 may be a 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 fourth 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 third compressor 120 of the present embodiment further compresses the natural gas that is sent to the second heat exchanger 310 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 expanded by the second expanding section 512 and the third expanding section 522 is used as a refrigerant for cooling the natural gas in the second heat exchanger 310 as in the first embodiment. The third compression unit 521 of the third compander 520 compresses the fluid used as the refrigerant in the second heat exchanger 310 and then compresses the fluid used as the refrigerant in the second compressor 510, Lt; / RTI >

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 120, and the seventh cooler 240, Liquid separated by the second gas-liquid separator 410, and the evaporated gas discharged from the storage tank 10 by the heat exchanger 512 and the third expansion portion 522,

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, < / RTI > 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 downstream 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 sent to the second heat exchanger 310.

The second valve 710 of this embodiment is installed on a line for sending the natural gas separated by the second gas-liquid separator 410 to the second heat exchanger 310 as in the first embodiment, Adjust the flow and pressure.

The third valve 30 of the present 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 first embodiment so that the flow rate of the liquefied natural gas And pressure.

The third 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 compressing section 521 and the third cooler 220 is sent to the second compander 510 as in the first embodiment.

The fourth compressor 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 compressing section 511 and the fourth cooler 230 is sent to the first compressor 110 as in the first embodiment.

The second compressor 115 of the present embodiment is similar to the first embodiment except that it is separated by the second gas-liquid separator 410 and then flows through the second valve 710 and is used as a refrigerant in the second heat exchanger 310 Compresses the natural gas and sends it to the fuel supply system. In the second compressor 115, similarly to the first embodiment, when the value sent by the sensor for measuring the pressure inside the storage tank 10 is lower than a predetermined value, the flow rate of the natural gas to be compressed is lowered, Value, it can be adjusted to increase the flow rate of natural gas to be compressed.

As in the first embodiment, the fifth cooler 215 of this embodiment is disposed downstream of the second compressor 115 to lower the temperature of the fluid passing through the second compressor 115 as well as the pressure.

The ship including the storage tank of the present embodiment may include a plurality of compressors and a plurality of coolers as in the first embodiment so that the natural gas may be subjected to a multi-stage compression process according to the pressure required by the engine.

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

As in the first embodiment, the natural gas is heat-exchanged with the refrigerant in the first heat exchanger 305, cooled, and then sent to the first gas-liquid separator 405, where the heavy hydrocarbon component is separated And the fluid expanded by the first expansion portion 501 is sent to the upper portion of the distillation column 900. The first expansion portion 501 of the first compander 500 is then sent to the upper portion of 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 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 and used as a refrigerant for cooling the natural gas as in the first embodiment And then sent to the first compression unit 502 of the first compander 500. The fluid sent to the first compression section 502 is compressed by the first compression section 502, cooled by the first refrigerator 200, and then sent to the first compressor 110, as in the first 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 fourth valve 705, as in the first embodiment.

The fluid compressed by the first compressing section 502 and cooled by the first cooler 200 is compressed by the first compressor 110 and cooled by the second cooler 210 as in the first embodiment And then branches to two flows.

One of the two streams of natural gas branched after passing through the first compressor 110 and the second cooler 210 is directly sent to the second heat exchanger 310 unlike the first embodiment But is further compressed by the third compressor 120, cooled by the seventh chiller 240, and then sent to the second heat exchanger 310.

Of the two streams of natural gas that have branched after passing through the first compressor 110 and the second compressor 210, the other stream is sent to the second compander 510 as in the first embodiment.

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.

The fluid expanded by the second expansion portion 512 and the third expansion portion 522 flows through the first compressor 110, the second compressor 210, the third compressor 120 And the third compressor 521 of the third compander 520 after being used as the refrigerant for cooling the natural gas that has passed through the seventh compressor 240 and the seventh compressor 240.

The fluid compressed by the third compression section 521 is cooled by the third 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 compressing section 511 is cooled by the fourth cooler 230 and then sent to the first compressor 110 again in the same manner as in the first embodiment so that the above- .

The natural gas which has passed through the first compressor 110, the second cooler 210, the third compressor 120 and the seventh cooler 240 and then sent to the second heat exchanger 310 flows through the second expander 512 ), The fluid expanded by the third expansion portion 522, the natural gas separated by the second gas-liquid separator 410, and the evaporation gas discharged from the storage tank 10, 600). The fluid having passed through the second heat exchanger 310 and the expansion means 600 and partially liquefied is sent to the second gas-liquid separator 410 in the same manner as in the first embodiment, Natural gas and natural gas that can not be liquefied and remain as gas are separated.

The liquefied natural gas separated by the second gas-liquid separator 410 is sent to the storage tank 10 after passing through the third valve 30 as in the first embodiment and is sent to the second gas-liquid separator 410 The natural gas separated by the natural gas is passed through the second valve 710 and then sent to the second heat exchanger 310 to be used as the refrigerant and then sent to the second compressor 115.

The fluid sent to the second compressor 115 after being used as a refrigerant in the second heat exchanger 310 is compressed by the second compressor 115 and cooled by the fifth cooler 215 as in the first embodiment And sent to the fuel supply system to be used as fuel for the engine.

On the other hand, as in the first embodiment, the natural gas separated by the second gas-liquid separator 410 is discharged from the second gas-liquid separator 410 to the second heat exchanger (not shown) 310 on the line.

The evaporated gas sent from the storage tank 10 to the second gas-liquid separator 410 through the second heat exchanger 310 is sent to the second gas-liquid separator 410 as in the first embodiment, Exchanged as a refrigerant in the second heat exchanger 310 and then sent through the second compressor 115 and the fifth cooler 215 to the fuel supply system.

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 fifth 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 compander 510, the third compander 520, the second heat exchanger (not shown) The third valve 30, the third cooler 220, the fourth cooler 230, the second compressor 308, the third compressor 309, the third compressor 309, the third compressor 309, the expansion unit 600, the second gas-liquid separator 410, the second valve 710, The second compressor 115, the fifth condenser 215, the third compressor 120, and the seventh condenser 240.

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 fifth 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 natural gas separated by the second gas-liquid separator 410 is sent to a line to be sent to the second heat exchanger 310, and the second gas-liquid separator (not shown) Is used as a refrigerant in the second heat exchanger (310) together with the natural gas sent from the separator (410) to the second heat exchanger (310). The liquefied natural gas separated by the second gas-liquid separator 410 is sent to the storage tank 10 through the third valve 30 as in the second embodiment.

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, 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 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 fourth 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 third compressor 120 of the present embodiment is configured such that the natural gas that has passed through the first compressor 110 and the second cooler 210 and that is sent to the second heat exchanger 310 Lt; / RTI >

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.

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 fifth 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 to control the flow rate and pressure of the liquefied natural gas do. In other words, the fifth valve 720 may be configured to take into account 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 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 once again And then sent to the second heat exchanger 310. The fluid expanded by the second expansion portion 512 and the third expansion portion 522 is used as a refrigerant for cooling the natural gas in the second heat exchanger 310 as in the second embodiment. The third compressing unit 521 of the third compander 520 compresses the fluid used as the refrigerant in the second heat exchanger 310 and then the second compresser 510 compresses the fluid used as the refrigerant in the second heat exchanger 310, Lt; / RTI >

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 120, and the seventh cooler 240, Liquid separated by the second gas-liquid separator 410, and the evaporated gas discharged from the storage tank 10 by the heat exchanger 512 and the third expansion portion 522,

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, < / RTI > 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 sent to the second heat exchanger 310.

The second valve 710 of this embodiment is installed on a line for sending the natural gas separated by the second gas-liquid separator 410 to the second heat exchanger 310 as in the second embodiment, Adjust the flow and pressure.

The third valve 30 of the present 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, And pressure.

The third 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 having passed through the third compressing section 521 and the third cooler 220 is sent to the second compander 510 as in the second embodiment.

The fourth compressor 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 compressing section 511 and the fourth cooler 230 is sent to the first compressor 110 as in the second embodiment.

The second compressor 115 of this embodiment is configured such that it is separated by the second gas-liquid separator 410 and then flows through the second valve 710 and is used as a refrigerant in the second heat exchanger 310 Compresses the natural gas and sends it to the fuel supply system. In the second compressor 115, similarly to the second embodiment, when the value sent by the sensor for measuring the pressure inside the storage tank 10 is lower than a predetermined value, the flow rate of the natural gas to be compressed is lowered, Value, it can be adjusted to increase the flow rate of natural gas to be compressed.

As in the second embodiment, the fifth cooler 215 of this embodiment is disposed downstream of the second compressor 115 to lower the temperature of the fluid passing through the second compressor 115 as well as the pressure.

The ship including the storage tank of this embodiment may include a plurality of compressors and a plurality of coolers as in the second embodiment so that the natural gas may undergo a multistage compression process according to the pressure required by the engine.

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

As in the second embodiment, the natural gas 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, where the heavy hydrocarbon component is separated And the fluid expanded by the first expansion portion 501 is sent to the upper portion of the distillation column 900. The first expansion portion 501 of the first compander 500 is then sent to the upper portion of 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 that has been subjected to fractional distillation by the distillation tower 900 and whose temperature is lowered from the upper portion of the distillation tower 900 is sent to the first heat exchanger 305 and used as a refrigerant for cooling the natural gas as in the second embodiment And then sent to the first compression unit 502 of the first compander 500. The fluid sent to the first compression section 502 is compressed by the first compression section 502, cooled by the first refrigerator 200, and then sent to the first compressor 110, as in the second 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 fourth valve 705, as in the second embodiment.

The fluid compressed by the first compression section 502 and cooled by the first cooling device 200 is compressed by the first compressor 110 and cooled by the second cooling device 210 in the same manner as in the second embodiment And then branches to two flows.

The two flows of natural gas branched after passing through the first compressor 110 and the second compressor 210 are further compressed by the third compressor 120, 7 cooler 240 and then to the second heat exchanger 310 and the other stream is sent to the second compander 510.

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 fluid that has passed through the second expansion portion 512 and then sent to the third gas-liquid separator 420 is separated from the natural gas and the liquefied natural gas.

The natural gas separated by the third gas-liquid separator 420 is sent to the third expansion unit 522 of the third compander 520 and expanded once again. The natural gas is then sent to the second heat exchanger 310, Is used.

The liquefied natural gas separated by the third gas-liquid separator 420 passes through the fifth valve 720 and is sent to the second heat exchanger 310 to be used as a refrigerant. After passing through the fifth valve 720, The liquefied natural gas used as the refrigerant in the second heat exchanger 310 is partly or wholly vaporized and sent from the third expansion portion 522 to the second heat exchanger 310 so that the third natural gas And sent to the panda 520.

The fluid sent to the third compander 520 after being used as a refrigerant in the second heat exchanger 310 is compressed by the third compression section 521 and cooled by the third condenser 220, And then compressed again by the second compression unit 511 of the second compander 510.

The fluid once again compressed by the second compression section 511 is cooled by the fourth cooler 230 and then sent to the first compressor 110 again in the same manner as the second embodiment, The process goes through again.

The natural gas sent to the second heat exchanger 310 after passing through the first compressor 110, the second cooler 210, the third compressor 120, and the seventh cooler 240 is, as in the second embodiment, The fluid expanded by the second expansion portion 512 and the third expansion portion 522, the natural gas separated by the second gas-liquid separator 410, and the evaporation gas discharged from the storage tank 10 After being cooled, it is inflated by expansion means (600). The fluid having passed through the second heat exchanger 310 and the expansion means 600 and partially liquefied is sent to the second gas-liquid separator 410 in the same manner as in the second embodiment, Natural gas and natural gas that can not be liquefied and remain as gas are separated.

The liquefied natural gas separated by the second gas-liquid separator 410 is sent to the storage tank 10 after passing through the third valve 30 as in the second embodiment and is sent to the second gas-liquid separator 410 The natural gas separated by the natural gas is passed through the second valve 710 and then sent to the second heat exchanger 310 to be used as the refrigerant and then sent to the second compressor 115. [

The fluid sent to the second compressor 115 after being used as the refrigerant in the second heat exchanger 310 is compressed by the second compressor 115 and cooled by the fifth cooler 215 in the same manner as in the second embodiment And sent to the fuel supply system to be used as fuel for the engine.

On the other hand, as in the second embodiment, the natural gas separated by the second gas-liquid separator 410 is discharged from the second gas-liquid separator 410 to the second heat exchanger (not shown) 310 on the line.

The evaporated gas sent from the storage tank 10 to the second gas-liquid separator 410 through the second heat exchanger 310 is sent to the second gas-liquid separator 410 as in the second embodiment, Exchanged as a refrigerant in the second heat exchanger 310 and then sent through the second compressor 115 and the fifth cooler 215 to the fuel supply system.

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 an 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.

3, the vessel 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, The first compressor 110, the second compressor 210, the second compressor 510, the third gas-liquid separator 420, the fifth valve 700, the first compressor 110, the second compressor 210, The first valve 720, the third compander 520, the second heat exchanger 310, the expansion means 600, the second gas-liquid separator 410, the second valve 710, the third valve 30, And further includes a cooler 220, a fourth cooler 230, a second compressor 115, a fifth cooler 215, a third compressor 120, and a seventh cooler 240.

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 that is sent from the second compander 510 to compress the fluid that has passed through the third heat exchanger 320; 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 natural gas separated by the second gas-liquid separator 410 is sent to the second heat exchanger 310 in a line to be sent to the second gas-liquid separator 310, as in the third embodiment, Is used as a refrigerant in the second heat exchanger (310) together with the natural gas sent from the separator (410) to the second heat exchanger (310). The liquefied natural gas separated by the second gas-liquid separator 410 is sent to the storage tank 10 through the third valve 30 as in the third embodiment.

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, 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 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 fourth 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 third compressor 120 of the present embodiment is a natural gas which is supplied to the second heat exchanger 310 from among the natural gas that has passed through the first compressor 110 and the second cooler 210, Lt; / RTI >

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.

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, Not to the third gas-liquid separator 420, but to the third heat exchanger 320 before that.

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 the third heat exchanger 320, the fluid whose pressure is raised by the fourth compressor 130 is cooled and a part of the fluid 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 this embodiment increases the pressure of the fluid 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, as in the third embodiment, 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 fifth valve 720 of this 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 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 expanded by the second expanding section 512 and the third expanding section 522 is used as a refrigerant for cooling the natural gas in the second heat exchanger 310 as in the third embodiment. The third compressing unit 521 of the third compander 520 compresses the fluid used as the refrigerant in the second heat exchanger 310 and then the second compresser 510 compresses the fluid used as the refrigerant in the second heat exchanger 310, Lt; / RTI >

The second heat exchanger 310 of the present embodiment is configured such that the first compressor 110, the second cooler 210, the third compressor 120, and the seventh cooler 240, Liquid separated by the second gas-liquid separator 410 and the evaporated gas discharged from the storage tank 10 and the natural gas separated by the second gas- Heat exchange is performed to cool.

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 supplied to the second heat exchanger 310 and the expansion means 600, < / RTI > 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 sent to the second heat exchanger 310.

The second valve 710 of this embodiment is installed on a line for sending the natural gas separated by the second gas-liquid separator 410 to the second heat exchanger 310 as in the third embodiment, Adjust the flow and pressure.

The third valve 30 of the present 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 third embodiment so that the flow rate of the liquefied natural gas And pressure.

The third 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 and is compressed But the temperature also lowers the temperature of the raised fluid. The fluid having passed through the third compressing section 521 and the third cooler 220 is sent to the second compander 510 as in the third embodiment.

The fourth compressor 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 only by the pressure But the temperature also lowers the temperature of the raised fluid. The fluid having passed through the second compressing section 511 and the fourth cooler 230 is sent to the first compressor 110 as in the third embodiment.

The second compressor 115 of the present embodiment is configured such that it is separated by the second gas-liquid separator 410 and then flows through the second valve 710 and is used as a refrigerant in the second heat exchanger 310 Compresses the natural gas and sends it to the fuel supply system. In the second compressor 115, similarly to the third embodiment, when the value sent by the sensor for measuring the pressure inside the storage tank 10 is lower than a predetermined value, the flow rate of the natural gas to be compressed is lowered, Value, it can be adjusted to increase the flow rate of natural gas to be compressed.

As in the third embodiment, the fifth cooler 215 of the present embodiment is disposed downstream of the second compressor 115 to lower the temperature of the fluid passing through the second compressor 115 as well as the pressure.

The ship including the storage tank of the present embodiment may include a plurality of compressors and a plurality of coolers as in the third embodiment so that natural gas may be subjected to a multistage compression process according to the pressure required by the engine.

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

As in the third embodiment, the natural gas is heat-exchanged with the refrigerant in the first heat exchanger 305 and cooled, and then sent to the first gas-liquid separator 405, where the heavy hydrocarbon component is separated And the fluid expanded by the first expansion portion 501 is sent to the upper portion of the distillation column 900. The first expansion portion 501 of the first compander 500 is then sent to the upper portion of 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 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 used as a refrigerant for cooling the natural gas as in the third embodiment And then sent to the first compression unit 502 of the first compander 500. The fluid sent to the first compression section 502 is compressed 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 fourth valve 705, as in the third embodiment.

The fluid that has been compressed by the first compressing section 502 and cooled by the first cooler 200 is compressed by the first compressor 110 and cooled by the second cooler 210 as in the third embodiment And then branches to two flows.

The two flows of natural gas branched after passing through the first compressor 110 and the second compressor 210 are further compressed by the third compressor 120, 7 cooler 240 and then to the second heat exchanger 310 and the other stream is sent to the second compander 510.

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 sent back to the third heat exchanger 320 to be heat exchanged in a second order with the fluid sent from the second expansion unit 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 fifth 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 is, as in the third embodiment, 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 liquefied natural gas used as the refrigerant in the second heat exchanger 310 after passing through the fifth valve 720 is partially or wholly vaporized in the same manner as in the third embodiment and is discharged from the third expansion portion 522 2 heat exchanger 310 and sent to the third compander 520 together with the fluid used as the refrigerant.

The fluid sent to the third compander 520 after being used as a refrigerant in the second heat exchanger 310 is compressed by the third compressing section 521 and is supplied to the third cooler 220 as in the third embodiment. And then once again compressed by the second compression section 511 of the second compander 510. [

The fluid once again compressed by the second compression section 511 is cooled by the fourth cooler 230 and then sent to the first compressor 110 again in the same manner as in the third embodiment, The process goes through again.

Natural gas that has passed through the first compressor 110, the second cooler 210, the third compressor 120, and the seventh cooler 240 and then sent to the second heat exchanger 310, The fluid expanded by the second expansion portion 512 and the third expansion portion 522, the natural gas separated by the second gas-liquid separator 410, and the evaporation gas discharged from the storage tank 10 After being cooled, it is inflated by expansion means (600). The fluid having passed through the second heat exchanger 310 and the expansion means 600 and partially liquefied is sent to the second gas-liquid separator 410 in the same manner as in the third embodiment, Natural gas and natural gas that can not be liquefied and remain as gas are separated.

The liquefied natural gas separated by the second gas-liquid separator 410 is sent to the storage tank 10 after passing through the third valve 30 as in the third embodiment and is sent to the second gas-liquid separator 410 The natural gas separated by the natural gas is passed through the second valve 710 and then sent to the second heat exchanger 310 to be used as the refrigerant and then sent to the second compressor 115.

The fluid sent to the second compressor 115 after being used as a refrigerant in the second heat exchanger 310 is compressed by the second compressor 115 and cooled by the fifth cooler 215 in the same manner as in the third embodiment And sent to the fuel supply system to be used as fuel for the engine.

On the other hand, as in the third embodiment, the natural gas separated by the second gas-liquid separator 410 is discharged from the second gas-liquid separator 410 to the second heat exchanger (not shown) 310 on the line.

The evaporated gas sent from the storage tank 10 to the second gas-liquid separator 410 through the second heat exchanger 310 is sent to the second gas-liquid separator 410, Exchanged as a refrigerant in the second heat exchanger 310 and then sent through the second compressor 115 and the fifth cooler 215 to the fuel supply system.

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
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 (20)

A first heat exchanger for cooling natural gas by heat exchange with a refrigerant;
A first gas-liquid separator for separating heavy hydrocarbons from the fluid cooled by the first heat exchanger;
A first expansion unit for expanding the fluid into which the heavy hydrocarbons have been separated by the first gas-liquid separator;
A first compression unit for compressing a fluid used as a refrigerant in the first heat exchanger;
A distillation column for distilling the medium hydrocarbon separated by the first gas-liquid separator and the fluid expanded by the first expansion unit;
A second heat exchanger for cooling a part of the refrigerant flow branched by the first compression unit (hereinafter referred to as "x-flow") by heat exchange with the refrigerant;
Expansion means for expanding the fluid cooled by said second heat exchanger;
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 second expanding unit for expanding a flow of the fluid compressed by the first compressing unit except for the 'x flow' (hereinafter referred to as 'y flow'); And
And a second compression unit that compresses the fluid used as the refrigerant in the second heat exchanger after being expanded by the second expansion unit,
The first compression section and the first expansion section constitute a first compander,
The second compression section and the second expansion section constitute a second compander,
The fluid discharged from the distillation column is supplied to the first compression unit after being used as a refrigerant in the first heat exchanger,
Wherein the second heat exchanger further comprises: a fluid expanded by the second expanding portion; And the natural gas separated by the second gas-liquid separator are used as a coolant to cool the 'x-flow'
The fluid having passed through the second compression section is merged into a line between the first compression section and the second heat exchanger. delete The method according to claim 1,
Wherein the evaporated gas discharged from the storage tank is combined with the natural gas separated by the second gas-liquid separator and used as a refrigerant of the second heat exchanger. A first heat exchanger for cooling natural gas by heat exchange with a refrigerant;
A first gas-liquid separator for separating heavy hydrocarbons from the fluid cooled by the first heat exchanger;
A first expansion unit for expanding the fluid into which the heavy hydrocarbons have been separated by the first gas-liquid separator;
A first compression unit for compressing a fluid used as a refrigerant in the first heat exchanger;
A distillation column for distilling the medium hydrocarbon separated by the first gas-liquid separator and the fluid expanded by the first expansion unit;
A second heat exchanger for cooling a part of the refrigerant flow branched by the first compression unit (hereinafter referred to as "x-flow") by heat exchange with the refrigerant;
Expansion means for expanding the fluid cooled by said second heat exchanger;
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 second expanding unit for expanding a flow of the fluid compressed by the first compressing unit except for the 'x flow' (hereinafter referred to as 'y flow');
A second compression unit for compressing a fluid used as a refrigerant in the second heat exchanger after being expanded by the second expansion unit; And
And a first compressor for compressing the fluid compressed by the first compression unit,
The first compression section and the first expansion section constitute a first compander,
The second compression section and the second expansion section constitute a second compander,
The fluid discharged from the distillation column is supplied to the first compression unit after being used as a refrigerant in the first heat exchanger,
Wherein the second heat exchanger further comprises: a fluid expanded by the second expanding portion; And the natural gas separated by the second gas-liquid separator are used as a coolant to cool the 'x-flow'
The fluid compressed by the first compressor and the first compressor is diverted into the 'x-flow' and the 'y-flow'
Wherein the fluid that has passed through the second compression section is merged into a line between the first compression section and the first compressor. A first heat exchanger for cooling natural gas by heat exchange with a refrigerant;
A first gas-liquid separator for separating heavy hydrocarbons from the fluid cooled by the first heat exchanger;
A first expansion unit for expanding the fluid into which the heavy hydrocarbons have been separated by the first gas-liquid separator;
A first compression unit for compressing a fluid used as a refrigerant in the first heat exchanger;
A distillation column for distilling the medium hydrocarbon separated by the first gas-liquid separator and the fluid expanded by the first expansion unit;
A second heat exchanger for cooling a part of the refrigerant flow branched by the first compression unit (hereinafter referred to as "x-flow") by heat exchange with the refrigerant;
Expansion means for expanding the fluid cooled by said second heat exchanger;
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 second expanding unit for expanding a flow of the fluid compressed by the first compressing unit except for the 'x flow' (hereinafter referred to as 'y flow'); And
And a second compression unit that compresses the fluid used as the refrigerant in the second heat exchanger after being expanded by the second expansion unit,
The first compression section and the first expansion section constitute a first compander,
The second compression section and the second expansion section constitute a second compander,
The fluid discharged from the distillation column is supplied to the first compression unit after being used as a refrigerant in the first heat exchanger,
Wherein the second heat exchanger further comprises: a fluid expanded by the second expanding portion; And the natural gas separated by the second gas-liquid separator are used as a coolant to cool the 'x-flow'
Wherein the natural gas used as a refrigerant in the second heat exchanger after being separated by the second gas-liquid separator is sent to a fuel supply system. A first heat exchanger for cooling natural gas by heat exchange with a refrigerant;
A first gas-liquid separator for separating heavy hydrocarbons from the fluid cooled by the first heat exchanger;
A first expansion unit for expanding the fluid into which the heavy hydrocarbons have been separated by the first gas-liquid separator;
A first compression unit for compressing a fluid used as a refrigerant in the first heat exchanger;
A distillation column for distilling the medium hydrocarbon separated by the first gas-liquid separator and the fluid expanded by the first expansion unit;
A second heat exchanger for cooling a part of the refrigerant flow branched by the first compression unit (hereinafter referred to as "x-flow") by heat exchange with the refrigerant;
Expansion means for expanding the fluid cooled by said second heat exchanger;
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 second expanding unit for expanding a flow of the fluid compressed by the first compressing unit except for the 'x flow' (hereinafter referred to as 'y flow');
A second compression unit for compressing a fluid used as a refrigerant in the second heat exchanger after being expanded by the second expansion unit;
A third expanding portion for once again expanding the fluid expanded by the second expanding portion; And
And a third compression unit for compressing the fluid used as the refrigerant in the second heat exchanger after being expanded by the third expansion unit,
The first compression section and the first expansion section constitute a first compander,
The second compression section and the second expansion section constitute a second compander,
The fluid discharged from the distillation column is supplied to the first compression unit after being used as a refrigerant in the first heat exchanger,
Wherein the second heat exchanger further comprises: a fluid expanded by the second expanding portion; And the natural gas separated by the second gas-liquid separator are used as a coolant to cool the 'x-flow'
The third compression section and the third expansion section constitute a third compander,
The fluid compressed by the third compression section is compressed by the second compression section,
Wherein the second heat exchanger comprises: a fluid expanded by the third expanding portion; And a natural gas separated by the second gas-liquid separator as a refrigerant. The method of claim 5,
Further comprising a second compressor installed on a line which is separated by said second gas-liquid separator and then sent to said fuel supply system for natural gas used as refrigerant in said second heat exchanger, Ships containing tanks. A first heat exchanger for cooling natural gas by heat exchange with a refrigerant;
A first gas-liquid separator for separating heavy hydrocarbons from the fluid cooled by the first heat exchanger;
A first expansion unit for expanding the fluid into which the heavy hydrocarbons have been separated by the first gas-liquid separator;
A first compression unit for compressing a fluid used as a refrigerant in the first heat exchanger;
A distillation column for distilling the medium hydrocarbon separated by the first gas-liquid separator and the fluid expanded by the first expansion unit;
A second heat exchanger for cooling a part of the refrigerant flow branched by the first compression unit (hereinafter referred to as "x-flow") by heat exchange with the refrigerant;
Expansion means for expanding the fluid cooled by said second heat exchanger;
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 second expanding unit for expanding a flow of the fluid compressed by the first compressing unit except for the 'x flow' (hereinafter referred to as 'y flow'); And
And a second compression unit that compresses the fluid used as the refrigerant in the second heat exchanger after being expanded by the second expansion unit,
The first compression section and the first expansion section constitute a first compander,
The second compression section and the second expansion section constitute a second compander,
The fluid discharged from the distillation column is supplied to the first compression unit after being used as a refrigerant in the first heat exchanger,
Wherein the second heat exchanger further comprises: a fluid expanded by the second expanding portion; And the natural gas separated by the second gas-liquid separator are used as a coolant to cool the 'x-flow'
The distillation column separates the condensate from the fluid sent to the distillation column,
And a sixth cooler for cooling the condensate discharged from the distillation column. A first heat exchanger for cooling natural gas by heat exchange with a refrigerant;
A first gas-liquid separator for separating heavy hydrocarbons from the fluid cooled by the first heat exchanger;
A first expansion unit for expanding the fluid into which the heavy hydrocarbons have been separated by the first gas-liquid separator;
A first compression unit for compressing a fluid used as a refrigerant in the first heat exchanger;
A distillation column for distilling the medium hydrocarbon separated by the first gas-liquid separator and the fluid expanded by the first expansion unit;
A second heat exchanger for cooling a part of the refrigerant flow branched by the first compression unit (hereinafter referred to as "x-flow") by heat exchange with the refrigerant;
Expansion means for expanding the fluid cooled by said second heat exchanger;
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 second expanding unit for expanding a flow of the fluid compressed by the first compressing unit except for the 'x flow' (hereinafter referred to as 'y flow'); And
And a second compression unit that compresses the fluid used as the refrigerant in the second heat exchanger after being expanded by the second expansion unit,
The first compression section and the first expansion section constitute a first compander,
The second compression section and the second expansion section constitute a second compander,
The fluid discharged from the distillation column is supplied to the first compression unit after being used as a refrigerant in the first heat exchanger,
Wherein the second heat exchanger further comprises: a fluid expanded by the second expanding portion; And the natural gas separated by the second gas-liquid separator are used as a coolant to cool the 'x-flow'
Wherein the fluid cooled by the second heat exchanger is in a supercritical state. The method of claim 4,
Further comprising a third compressor for further compressing the fluid compressed by the first compressor,
Wherein the fluid compressed by the first compressor and the third compressor is cooled by heat exchange with the refrigerant in the second heat exchanger. The method of claim 6,
Further comprising a third gas-liquid separator for passing natural gas remaining in a gaseous state and partially liquefied natural gas passing through the second expansion portion,
The natural gas separated by the third gas-liquid separator is sent to the third expansion unit,
Wherein the second heat exchanger further comprises: liquefied natural gas separated by the third gas-liquid separator; A fluid inflated by the third inflation section; And a natural gas separated by the second gas-liquid separator as a refrigerant. The method of claim 11,
A third heat exchanger that uses the fluid expanded by the second expansion unit as a refrigerant; And
And a fourth compressor for compressing the fluid used as the refrigerant in the third heat exchanger after being expanded by the second expansion part,
Wherein the fluid compressed by the fourth compressor is cooled by heat exchange with fluid refrigerant expanded by the second expansion part in the third heat exchanger and then sent to the third gas-liquid separator Ship. A distillation system for separating condensed and heavy hydrocarbon components contained in natural gas;
A refrigerant system for cooling natural gas from which condensate and heavy hydrocarbons are separated by the distillation system;
A liquefaction system for liquefying natural gas using natural gas cooled by the refrigerant system and evaporation gas supplied from a storage tank as a refrigerant;
An evaporation gas supply system for supplying evaporation gas discharged from the storage tank to the liquefaction system; And
And a fuel supply system for supplying natural gas used as a refrigerant to the fuel of the engine in the liquefaction system,
The distillation system comprises:
A first heat exchanger for cooling the natural gas; And
And a first compander including a first expansion portion and a first compression portion,
Wherein the natural gas cooled by the first heat exchanger is expanded by the first expansion portion,
The natural gas from which the condensate and the heavy hydrocarbon components are separated is used as a refrigerant for cooling the natural gas in the first heat exchanger and then compressed by the first compression unit,
Wherein the refrigerant system is an open loop. delete 14. The method of claim 13,
In the refrigerant system,
A third heat exchanger for self-heat-exchanging the natural gas supplied from the distillation system to cool the natural gas; And
And a fourth compressor for compressing the natural gas used as the refrigerant in the third heat exchanger and then returning the natural gas to the third heat exchanger,
Wherein the third heat exchanger comprises a storage tank for cooling the natural gas compressed by the fourth compressor by heat-exchanging natural gas supplied from the distillation system with a refrigerant. 14. The method of claim 13,
Wherein the natural gas supplied from the refrigerant system and used as a refrigerant in the liquefaction system is merged with the natural gas supplied from the distillation system. 1) cooling the natural gas by heat exchange with the fluid discharged from the distillation tower,
2) separating the heavy hydrocarbons from the fluid cooled by heat exchange in step 1)
3) In the step 2), the separated hydrocarbon is expanded and sent to the upper part of the distillation tower,
4) The heavy hydrocarbon separated in the step 2) is sent to the center of the distillation column,
5) 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 in the step 1)
6) compressing the fluid used as the refrigerant for cooling the natural gas in the step 1) by using the energy released when the hydrocarbons separate the fluid in the step 3)
7) The fluid compressed in the step 6) is branched into two flows,
8) Of the two flows branched in the step 7), one flow (hereinafter referred to as a flow) is expanded,
9) The 'a flow' expanded in the step 8) is used as a refrigerant and the other flow (hereinafter referred to as a 'b flow') branched in the step 7)
10) The 'b-flow' cooled in the step 9) is expanded to partially liquefy,
11) The 'b-flow' partly liquefied in the step 10) separates the natural gas and the liquefied natural gas,
12) The natural gas separated in the step 11) is used as a refrigerant for cooling by heat-exchanging the 'b-flow' in the step 9)
13) The 'a flow' after being used as the refrigerant for the heat exchange cooling the 'b flow' in the step 9) is compressed by the energy released when the 'a flow' is expanded in the step 8) , Way. 18. The method of claim 17,
In the step 8), the 'a flow' is further compressed and then expanded. The method according to claim 17 or 18,
8-4) The " a flow " expanded in the step 8) is a state in which the liquefied natural gas and the gaseous natural gas are separated,
The gaseous natural gas separated from the 'a flow' in the step 8-4) is used as a refrigerant to be cooled by heat exchange with the 'b flow' in the step 9)
The liquefied natural gas separated from the 'a flow' in the step 8-4) is used as a refrigerant to cool by heat-exchanging the 'b flow' in the step 9). The method of claim 19,
8-1) The 'a flow' expanded in the step 8) is used as a refrigerant in the third heat exchanger,
8-2) In step 8-1), the 'a flow' used as the refrigerant of the third heat exchanger is compressed,
8-3) The 'a flow' compressed in step 8-2) is a refrigerant which is cooled by heat exchange by the third heat exchanger with the refrigerant 'a flow' expanded in the step 8-1)
The fluid cooled by the third heat exchanger in the step 8-3) is separated from the liquefied natural gas and the gaseous natural gas in the step 8-4).

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