KR20160144738A - Vessel Including Storage Tanks - Google Patents

Abstract

According to the present invention, disclosed is a vessel including storage tanks, to simplify a system and conveniently operate the system without using an individual coolant system. The vessel comprises: a first compressing to compress natural gas supplied from the outside of a system; a first cooler to cool the natural gas compressed by the first compressor; a first and a second compander to expand or compress a fluid; a first heat exchanger performing self-heat exchange of the natural gas to cool the natural gas; an expansion means to expand the fluid passing the first heat exchanger; a third cooler to cool the fluid passing the first compander; a fourth cooler to cool the fluid passing the second compander; and a first valve installed in a line to send evaporated gas inside the storage tank to the first heat exchanger to adjust a flowrate and a pressure of the evaporated gas sent to the first heat exchanger from the storage tank. The first heat exchanger uses the fluid branched after passing the first compressor and cooler, and expanded by the first and/or second expander as coolant to cool the other part of natural gas branched after passing the first compressor and cooler. A part of the natural gas supplied from the outside of the system is branched in a front end of the first compressor to be sent to a low pressure fuel supply system.

Description

[0001] VESSEL Including Storage Tanks [0002]

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

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

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

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

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

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

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

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

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

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

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

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

According to an aspect of the present invention, there is provided a ship including a storage tank, comprising: a first compressor for compressing natural gas supplied from outside the system; A first cooler for cooling the natural gas compressed by the first compressor; A first compander and a second compander for expanding or compressing the fluid; A first heat exchanger for self-heat-exchanging natural gas to cool the natural gas; Expansion means for expanding the fluid that has passed through the first heat exchanger; A third cooler for cooling the fluid passing through the first compander; A fourth cooler for cooling the fluid passing through the second compander; And a first valve installed on a line for sending evaporated gas in the storage tank to the first heat exchanger to regulate the flow rate and pressure of the evaporated gas sent from the storage tank to the first heat exchanger, The first heat exchanger comprising: a fluid which is split after passing through the first compressor and the first cooler and expanded by at least one of the first compander and the second compander; And a cooling gas discharged from the storage tank as a refrigerant to cool another natural gas branched after passing through the first compressor and the first cooler and a part of the natural gas supplied from the outside of the system , And a storage tank branched from the upstream side of the first compressor and sent to a low-pressure fuel supply system.

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

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

The first compander may include a first expanding portion for expanding the fluid and a first compressing portion for compressing the fluid and the second compander includes a second expanding portion for expanding the fluid and a second expanding portion for compressing the fluid, 2 compressing portion, and the first expanding portion is axially connected to the first compressing portion, the first expanding portion is capable of compressing the fluid by the energy obtained by expanding the fluid, and the second expanding portion compresses the fluid Wherein the first expansion portion and the second expansion portion are pivotally connected to the second compression portion such that the second expansion portion can compress the fluid by the energy obtained by expanding the fluid and the fluid expanded by at least one of the first expansion portion and the second expansion portion , The pressure can be restored by at least one of the first compression unit and the second compression unit, and then sent back to the first compressor.

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

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

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

A vessel including the storage tank includes a second gas-liquid separator for passing natural gas remaining in a gaseous state and partially liquefied natural gas passing through the first compander; And a fourth valve for controlling a flow rate and a pressure of the liquefied natural gas separated by the second gas-liquid separator and sent to the first heat exchanger, wherein the gas- Natural gas may be sent to the second compander, wherein the first heat exchanger is a liquefied natural gas separated by the second gas-liquid separator and passed through the fourth valve; And a fluid having passed through the second compander after being separated by the second gas-liquid separator may be used as a refrigerant.

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

According to another aspect of the present invention, there is provided a compressor comprising: a first compressor for compressing natural gas supplied from the outside; a first expander of a first compander for expanding a fluid that has passed through the first compressor; A second expansion unit of a second compander for further expanding the fluid expanded by the first expansion unit, a first heat exchanger using the fluid expanded by the second expansion unit as a refrigerant, A second compression section of said second compander for compressing the fluid used and a second compression section for compressing the fluid compressed by said second compression section and then to said first compressor A refrigerant system; A fuel supply system for supplying a part of the natural gas supplied from the outside to the fuel of the engine; And a first valve disposed on a line that directs the evaporated gas in the storage tank to the first heat exchanger to regulate the flow rate and pressure of the evaporated gas sent from the storage tank to the first heat exchanger, system; And the first heat exchanger for cooling the natural gas that has passed through the first compressor by using the first compressor, the refrigerant supplied by the refrigerant system, and the evaporation gas supplied from the storage tank, and the first heat exchanger Wherein the first compressor is used in conjunction with the fuel supply system, wherein the first compressor is used in conjunction with the fuel supply system, and wherein the vessel comprises a storage tank do.

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

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

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

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

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

According to another aspect of the present invention for achieving the above object, there is provided a system for supplying a part of natural gas supplied from outside the system to a low-pressure fuel supply system, compressing and cooling another part, The natural gas in one flow is further compressed and cooled and sent to the high-pressure fuel supply system, and the natural gas in the other flow (hereinafter referred to as " a flow & (Hereinafter, referred to as "b-flow") is expanded, and then the expanded b-flow and the evaporation gas are used as refrigerant, and the other of the branched a- (Hereinafter referred to as " c-flow "), and the c-flow which is heat-exchanged with the b-flow as the refrigerant is expanded and partially or entirely liquefied, c flow is compressed by the energy released when the b-flow is expanded, and is again compressed and cooled together with the natural gas supplied from outside the system.

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

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

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

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

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

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

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

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

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

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

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

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

Referring to FIG. 1, a vessel including the storage tank of this embodiment includes a first compressor 110 for compressing natural gas supplied to the system; A first cooler 210 for cooling the natural gas compressed by the first compressor 110; A second compressor (115) for compressing the natural gas having passed through the first compressor (110) and the first cooler (210) and sending the compressed natural gas to the high pressure fuel supply system; A second cooler 215 for cooling the natural gas that has passed through the second compressor 115; A first compander 510 and a second compander 520 for expanding or compressing the fluid; A first heat exchanger (310) for cooling the natural gas using the expanded fluid and the evaporation gas as refrigerant; Expansion means (600) for expanding the fluid having passed through the first heat exchanger (310); A third cooler 220 for cooling the fluid passing through the first compander 510; A fourth cooler 230 for cooling the fluid passing through the second compander 520; And a first valve (20) installed on a line for sending the evaporated gas in the storage tank (10) to the first heat exchanger (310); .

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

The first compressor (110) of this embodiment compresses the natural gas supplied from outside the system. The vessel including the storage tank of this embodiment is for liquefying the natural gas having passed through the first compressor 110 through the first 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 first heat exchanger 310 in order to increase the liquefaction efficiency in the first 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, the natural gas in the relatively low pressure state (X in FIG. 5) is passed through the first heat exchanger 310 and the expansion means 600 to lower the temperature and the 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, it is known that the liquefaction efficiency increases as the natural gas pressure is increased before the natural gas passes through the first heat exchanger 310, and the liquefaction can be theoretically 100% 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 first 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 first cooler 210 of the present embodiment lowers the temperature of the natural gas that has passed through the first compressor 110 and has increased temperature as well as pressure. The first cooler 210 can cool natural gas by, for example, heat-exchanging natural gas with fresh water at about room temperature.

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

The second cooler 215 of the present embodiment is disposed at the downstream end of the second compressor 115 and passes through the second compressor 115 to lower the temperature of the natural gas as well as the pressure. The second cooler 215 can cool the fluid by, for example, heat-exchanging fluid with fresh water at about room temperature.

The first compander 510 of the present embodiment includes a first expansion portion 512 for expanding the fluid and a first compression portion 511 for compressing the fluid. The first expanding part 512 and the first compressing part 511 are connected by an axis so that the first compressing part 511 compresses the fluid by the energy obtained by expanding the fluid by the first 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 first expansion unit 512 of the first compander 510 expands a portion of the natural gas that has passed through the first compressor 110 and the first compressor 210 and then sends the expanded natural gas to the second compander 520 The first compressing unit 511 compresses the fluid sent from the second compander 520 and sends the compressed fluid to the first compressor 110 again.

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

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

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

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

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

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

The third cooler 220 of the present embodiment is disposed at the downstream end of the second compression section 521 of the second compander 520 and is provided with the temperature of the fluid passing through the second compression section 521, . The fluid having passed through the second compressing section 521 and the third cooler 220 is sent to the first compander 510.

The fourth cooler 230 of the present embodiment is disposed at the downstream end of the first compressing section 511 of the first compander 510 and is provided with the temperature of the fluid passing through the first compressing section 511, . The fluid that has passed through the first compression unit 511 and the fourth cooling unit 230 is sent to the first compressor 110 together with the natural gas supplied to the system.

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

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

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

Some of the natural gas supplied from the outside of the system is branched and sent to the low-pressure fuel supply system, and the remaining part is compressed by the first compressor 110, cooled by the first cooler 210, Branch.

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

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

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

It is inefficient to lower the pressure of the natural gas compressed by the first compressor 110 and to use it in the low pressure engine so that before the natural gas passes through the first compressor 110, To a fuel supply system of a low-pressure engine such as a DF engine.

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

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

Natural gas that has passed through the first compressor 110 and the first cooler 210 and then sent to the first compander 510 is expanded by the first expansion unit 512 and then introduced into the second compander 520 And is sent to the second bulging portion 522. The fluid once again expanded by the second expansion part (522) is sent to the first heat exchanger (310).

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

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

The fluid compressed by the second compression unit 521 is cooled by the third cooling unit 220 and then sent to the first compander 510 and compressed again by the first compression unit 511 . The fluid compressed by the first compressing unit 511 is cooled by the fourth cooler 230 and then sent to the first compressor 110 together with the natural gas supplied from the outside of the system to perform the above- Again.

That is, the fluid used as the refrigerant after being expanded by the first expanding section 512 and the second expanding section 522 flows through the first expanding section 512 and the second expanding section 522, Is compressed by the first compression section 511 and the second compression section 521 and is sent to the first compressor 110 after restoring the pressure when natural gas is supplied to the system.

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

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

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

Referring to FIG. 2, the ship including the storage tank of the present embodiment includes a first compressor 110, a first cooler 210, a second compressor 115, a second cooler 215 The first compressor 510, the second compressor 520, the first heat exchanger 310, the expansion means 600, the third cooler 220, the fourth cooler 230 and the first valve 20).

However, the ship including the storage tank of this embodiment is different from the first embodiment in that the third compressor 120 additionally compresses the natural gas firstly compressed by the first compressor 110; A fifth cooler 240 for lowering the temperature of the natural gas passing through the third compressor 120; A first gas-liquid separator (410) installed downstream 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 first gas-liquid separator (410); And a third valve 30 for controlling the flow rate and pressure of the liquefied natural gas separated from the first gas-liquid separator 410 and sent to the storage tank 10.

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

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

As in the first embodiment, the first compressor 110 of this embodiment compresses the natural gas supplied from the outside of the system, and the first cooler 210 of this embodiment, similarly to the first embodiment, (110) to lower the temperature of the natural gas as well as the pressure.

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

The second cooler 215 of the present embodiment is installed at the downstream end of the second compressor 115 to pass through the second compressor 115 and lower the temperature of the natural gas not only in pressure but also in temperature as in the first embodiment .

The third compressor 120 of this embodiment further compresses the natural gas that has not been sent to the fuel supply system among the natural gas that has passed through the first compressor 110 and the first cooler 210. As described above, it is advantageous in terms of liquefaction efficiency to increase the pressure of the natural gas before the natural gas passes through the first heat exchanger 310. It is not sufficient to compress the natural gas to a sufficient pressure with only the first compressor 110 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 fifth cooler 240 of the present embodiment lowers the temperature of the natural gas that passes through the third compressor 120 and increases not only in pressure but also in temperature. For example, by exchanging heat between natural gas and fresh water at a room temperature, Natural gas can be cooled.

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

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

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

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

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

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

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

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

The second valve 710 of this embodiment is installed on a line for sending natural gas between the second expansion portion 522 and the first heat exchanger 310 from the first gas-liquid separator 410, Adjust the pressure. In consideration of the flow rate of the fluid passing through the second expansion portion 522 and sent to the first heat exchanger 310 and the capacity of the first heat exchanger 310, The amount of natural gas sent from the separator 410 to the second expansion unit 522 and the first heat exchanger 310 is controlled and is sent to the first heat exchanger 310 through the second expansion unit 522 Controls the pressure of the natural gas so that the pressure of the natural gas sent from the first gas-liquid separator (410) to the second expansion portion (522) and the first heat exchanger (310) becomes similar.

The third valve 30 of the present embodiment is installed on a line for sending liquefied natural gas separated from the first 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 rear end of the second compression section 521 of the second compander 520 and passes through the second compression section 521 and is compressed only by pressure But the temperature also lowers the temperature of the raised fluid. The fluid having passed through the second compressing section 521 and the third cooler 220 is sent to the first compander 510.

The fourth cooler 230 of the present embodiment is disposed at the rear end of the first compressing section 511 of the first compander 510 and passes through the first compressing section 511, But the temperature also lowers the temperature of the raised fluid. The fluid that has passed through the first compression unit 511 and the fourth cooling unit 230 is sent to the first compressor 110 together with the natural gas supplied to the system.

The first valve 20 of the present embodiment is provided on the line for sending the vaporized gas in the storage tank 10 to the first heat exchanger 310 and is supplied from the storage tank 10 1 heat exchanger (310).

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

As in the first embodiment, the natural gas supplied from the outside of the system is partially branched and sent to the low-pressure fuel supply system, and the remaining part is compressed by the first compressor 110 and is supplied by the first cooler 210 After cooling, it branches again into two streams.

Natural gas, which is compressed by the first compressor 110, cooled by the first cooler 210, and then diverted into two flows, flows in the same manner as in the first embodiment, 2 cooler 215 and then to the high-pressure fuel supply system, and the other flow branches again into two flows.

Unlike the first embodiment, the natural gas, which has passed through the first compressor 110 and the first cooler 210 and then branched into two flows without being sent to the high-pressure fuel supply system, 1 heat exchanger 310 but is sent to the first heat exchanger 310 after passing through the third compressor 120 and the fifth cooler 240 and the other flow is not sent to the first heat exchanger 310, , And then sent to the first compander 510.

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

Natural gas that has passed through the first compressor 110 and the first cooler 210 and then sent to the first compander 510 is expanded by the first expansion unit 512, 2 compander 520. The second expanding portion 522 of the second compander 520 is then moved to the second expanding portion 522 of the second compander 520. The fluid once again expanded by the second expanding section 522 is sent to the first heat exchanger 310 as in the first embodiment.

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

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

The fluid compressed by the second compression unit 521 is cooled by the third cooler 220 and then sent to the first compander 510 so that the first compression unit 511 is cooled, Lt; / RTI > The fluid compressed by the first compression section 511 is cooled by the fourth cooler 230 and then supplied to the first compressor 110 together with the natural gas supplied from the outside of the system And the above-described series of steps is again performed.

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

Unlike the first embodiment, the fluid having passed through the first heat exchanger 310 and the expansion means 600 and partially or fully liquefied is not directly sent to the storage tank 10 in a vapor-liquid mixed state, 1 gas-liquid separator 410 separates the liquid phase and the gas phase. The liquefied natural gas separated by the first 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 first gas- 2 valve 710 and is then sent to the first heat exchanger 310 together with the fluid that has passed through the second expansion portion 522 to be used again as a refrigerant.

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

The ship including the storage tank of the third embodiment shown in Fig. 3 has the second gas-liquid separator 420 and the fourth 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, a vessel including the storage tank of the present embodiment includes a first compressor 110, a first cooler 210, a second compressor 115, a second cooler 215 A third compressor 120, a fifth compressor 240, a first compander 510, a second compressor 520, a first heat exchanger 310, an expansion means 600, a first gas- A second valve 710, a third valve 30, a third cooler 220, a fourth cooler 230, and a first valve 20.

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

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

As in the second embodiment, the first compressor 110 of this embodiment compresses the natural gas supplied from the outside of the system, and the first cooler 210 of this embodiment, similarly to the second embodiment, (110) to lower the temperature of the natural gas as well as the pressure.

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

The second cooler 215 of the present embodiment is disposed at the downstream end of the second compressor 115 to lower the temperature of the natural gas that has passed through the second compressor 115 and has increased in temperature as well as pressure .

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

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

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

The first compressing unit 511 of the first compander 510 compresses the fluid sent from the second compander 520 and sends the compressed fluid to the first compressor 110 in the same manner as in the second embodiment.

The second gas-liquid separator (420) of this embodiment separates the liquefied natural gas and the remaining natural gas from the liquefied natural gas passing through the first expansion portion (512), and the liquefied natural gas is introduced into the first heat exchanger To be used as a refrigerant, and the natural gas is sent to the second compander 520 to be further expanded by the second expansion portion 522.

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

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

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

The second expansion portion 522 of the second compander 520 is expanded primarily by the first expansion portion 512 of the first compander 510 but can not be liquefied and the second expansion portion 522 of the second gas- To the first heat exchanger (310). The fluid inflated by the first expansion portion 512 and the second expansion portion 522 together with the evaporated gas discharged from the storage tank 10 in the first heat exchanger 310 It is used as a refrigerant to cool natural gas.

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

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

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

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

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

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

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

The third cooler 220 of the present embodiment is installed at the downstream end of the second compression section 521 of the second compander 520 and passes through the second compression section 521 But the temperature also lowers the temperature of the raised fluid. The fluid having passed through the second compressing section 521 and the third cooler 220 is sent to the first compander 510.

The fourth compressor 230 of the present embodiment is disposed at the rear end of the first compression section 511 of the first compander 510 and passes through the first compression section 511 But the temperature also lowers the temperature of the raised fluid. The fluid that has passed through the first compression unit 511 and the fourth cooling unit 230 is sent to the first compressor 110 together with the natural gas supplied to the system.

The first valve 20 of the present embodiment is provided on the line for sending the vaporized gas in the storage tank 10 to the first heat exchanger 310 and is supplied from the storage tank 10 1 heat exchanger (310).

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

As in the second embodiment, the natural gas supplied from the outside of the system is branched and sent to the low-pressure fuel supply system, and the remaining part of the natural gas is compressed by the first compressor 110 and discharged by the first cooler 210 After cooling, it branches again into two streams.

Natural gas, which is compressed by the first compressor 110, cooled by the first cooler 210, and then diverted into two flows, flows in the same direction as the second embodiment, 2 cooler 215 and then to the high-pressure fuel supply system, and the other flow branches again into two flows.

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

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

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

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

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

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

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

The fluid compressed by the second compressing unit 521 is cooled by the third cooler 220 and then sent to the first compander 510 so as to be supplied to the first compressing unit 511, Lt; / RTI > The fluid compressed by the first compressing section 511 is cooled by the fourth cooler 230 and then supplied to the first compressor 110 together with the natural gas supplied from the outside of the system And the above-described series of steps is again performed.

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

The fluid having passed through the first heat exchanger 310 and the expansion means 600 and partially or completely liquefied is separated from the liquid phase and the gas phase by the first gas-liquid separator 410, as in the second embodiment. The liquefied natural gas separated by the first 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 supplied to the first gas-liquid separator 410 After passing through the second valve 710, the natural gas separated by the natural gas is sent to the first heat exchanger 310 together with the fluid that has passed through the second expansion portion 522, Is used.

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

The ship including the storage tank of the fourth embodiment shown in FIG. 4 is different from the ship including the storage tank of the third embodiment shown in FIG. 3 in that the second heat exchanger 320, the fourth compressor 130, There is a difference in that it further includes the sixth 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.

Referring to FIG. 4, the ship including the storage tank of the present embodiment includes a first compressor 110, a first cooler 210, a second compressor 115, a second cooler 215 A third compressor 120, a fifth compressor 240, a first compander 510, a second gas-liquid separator 420, a fourth valve 720, a second compander 520, a first heat exchanger The third valve 30, the third cooler 220, the fourth cooler 230, and the first valve (not shown) (20).

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

As in the third embodiment, it is preferable that a plurality of the storage tanks 10 installed in the ship of this embodiment are provided in parallel to each other in the longitudinal direction of the hull, and that the space inside the hull is easy to utilize. The evaporated gas generated in the storage tank 10 is sent to the second heat exchanger 310 from the second compander 520 on the line to which the fluid is sent, 520 is used as a refrigerant for cooling the natural gas in the first heat exchanger 310 together with the fluid to be sent to the first heat exchanger 310.

 The first compressor (110) of this embodiment compresses the natural gas supplied from the outside of the system in the same manner as the third embodiment, and the first cooler (210) of the present embodiment is similar to the third embodiment, (110) to lower the temperature of the natural gas as well as the pressure.

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

The second cooler 215 of the present embodiment is disposed at the downstream end of the second compressor 115 to pass through the second compressor 115 and lower the temperature of the natural gas not only in pressure but also in temperature .

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

As in the third embodiment, the fifth cooler 240 of the present embodiment lowers the temperature of the natural gas not only the pressure but also the temperature, which passes through the third compressor 120.

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

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

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

The second heat exchanger 320 of the present embodiment is configured such that the fluid that has passed through the first expansion portion 512 and the fourth compressor 130 and the sixth cooler 250 after passing through the second heat exchanger 320 Exchanges the fluid that has passed therethrough. That is, the second heat exchanger 320 uses the fluid that has passed through the second inflator as the refrigerant, and passes through the fourth compressor 130 and the sixth cooler 250 to liquefy the fluid having a high pressure.

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).

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

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

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

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

The second 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 heat exchanger (320) and, as in the third embodiment, And the natural gas is sent to the second compander 520 so that it can be further expanded by the second expansion part 522.

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

As in the third embodiment, the second compander 520 of the present embodiment includes a second expanding section 522 for expanding the fluid and a second compressing section 521 for compressing the fluid. The second expanding section 522 and the second compressing section 521 are coupled by an axis in the same manner as in the third embodiment so that the energy of the second expanding section 522 inflating the fluid causes the second compressing section 521 compress the fluid.

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

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

The first heat exchanger 310 of the present embodiment is configured such that the first heat exchanger 310 and the second heat exchanger 310 are arranged in the same manner as in the third embodiment except that the first and second heat exchangers 310, The gas is cooled by self-heat exchange with the refrigerant.

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

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

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

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

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

The third cooler 220 of the present embodiment is installed at the rear end of the second compressing section 521 of the second compander 520 and passes through the second compressing section 521, But the temperature also lowers the temperature of the raised fluid. The fluid having passed through the second compressing section 521 and the third cooler 220 is sent to the first compander 510.

The fourth cooler 230 of the present embodiment is disposed at the rear end of the first compression section 511 of the first compander 510 and passes through the first compression section 511 But the temperature also lowers the temperature of the raised fluid. The fluid that has passed through the first compression unit 511 and the fourth cooling unit 230 is sent to the first compressor 110 together with the natural gas supplied to the system.

The first valve 20 of the present embodiment is installed on a line for sending the vaporized gas in the storage tank 10 to the first heat exchanger 310 as in the third embodiment, 1 heat exchanger (310).

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

As in the third embodiment, the natural gas supplied from the outside of the system is partially branched and sent to the low-pressure fuel supply system, and the remaining part of the natural gas is compressed by the first compressor 110 and is supplied by the first cooler 210 After cooling, it branches again into two streams.

Natural gas, which is compressed by the first compressor 110, cooled by the first cooler 210, and then diverted into two flows, flows in the same manner as in the third embodiment, 2 cooler 215 and then to the high-pressure fuel supply system, and the other flow branches again into two flows.

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

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

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

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

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

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

The fluid separated by the second gas-liquid separator 420, passed through the second expansion portion 522, and then sent to the first heat exchanger 310 is evaporated from the storage tank 10 as in the third embodiment The fluid partially or wholly vaporized and partially or fully vaporized after heat exchange with the natural gas in the first heat exchanger 310 is supplied to the second gas-liquid separator 420 from the second gas-liquid separator 420 1 heat exchanger 310 to be combined with the fluid used as the refrigerant and sent to the second compression section 521 of the second compander 520.

The fluid compressed by the second compressing unit 521 is cooled by the third cooler 220 and then sent to the first compander 510 so as to be supplied to the first compressing unit 511, Lt; / RTI > The fluid compressed by the first compression section 511 is cooled by the fourth cooler 230 and then supplied to the first compressor 110 together with the natural gas supplied from the outside of the system And the above-described series of steps is again performed.

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

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

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

10: Storage tank 20, 30, 710, 720: Valve
110, 115, 120, 130: compressor
210, 215, 220, 230, 240, 250: cooler
310, 320: heat exchanger 410, 420: gas-liquid separator
510, 520: Compander 511, 521:
512, 522: expanding part 600: expansion means

Claims (19)

1. A ship comprising a storage tank,
A first compressor for compressing natural gas supplied from outside the system;
A first cooler for cooling the natural gas compressed by the first compressor;
A first compander and a second compander for expanding or compressing the fluid;
A first heat exchanger for self-heat-exchanging natural gas to cool the natural gas;
Expansion means for expanding the fluid that has passed through the first heat exchanger;
A third cooler for cooling the fluid passing through the first compander;
A fourth cooler for cooling the fluid passing through the second compander; And
And a first valve installed on a line for sending the evaporated gas in the storage tank to the first heat exchanger to regulate the flow rate and pressure of the evaporated gas sent from the storage tank to the first heat exchanger,
The first heat exchanger comprising: a fluid which is split after passing through the first compressor and the first cooler and expanded by at least one of the first compander and the second compander; And an evaporation gas exhausted from the storage tank as a refrigerant to cool another part of the natural gas branched after passing through the first compressor and the first cooler,
Wherein part of the natural gas supplied from the outside of the system is branched at the front end of the first compressor and sent to the low pressure fuel supply system. The method according to claim 1,
A second compressor for compressing the natural gas having passed through the first compressor and the first cooler; And
A second cooler for cooling the natural gas compressed by the second compressor;
Further comprising:
Wherein the natural gas having passed through the first compressor, the first cooler, the second compressor, and the second cooler is sent to a high-pressure fuel supply system. The method according to claim 1 or 2,
Wherein the natural gas having passed through the first compressor is in a supercritical fluid state. The method according to claim 1 or 2,
Wherein the first compander includes a first expanding portion for expanding the fluid and a first compressing portion for compressing the fluid,
The second compander includes a second expanding portion for expanding the fluid and a second compressing portion for compressing the fluid,
The first expanding portion is axially connected to the first compressing portion so that the first expanding portion compresses the fluid by the energy obtained by expanding the fluid,
The second expanding portion is axially connected to the second compressing portion, the second expanding portion compresses the fluid by the energy obtained by expanding the fluid,
Wherein the fluid expanded by at least one of the first expanding portion and the second expanding portion is returned to the first compressor after the pressure is restored by at least one of the first compressing portion and the second compressing portion, A vessel including a storage tank. The method according to claim 1 or 2,
Wherein the expansion means is an expansion valve or inflator. The method according to claim 1 or 2,
A third compressor for additionally compressing the natural gas compressed by the first compressor;
A fifth cooler for lowering the temperature of the natural gas passing through the third compressor;
A first 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 valve for regulating the flow rate and pressure of the natural gas separated by the first gas-liquid separator; And
And a third valve for controlling the flow rate and pressure of the liquefied natural gas separated by the first gas-liquid separator and sent to the storage tank,
The natural gas having passed through the first compressor, the first cooler, the third compressor, and the fifth cooler is cooled in the first heat exchanger,
Wherein the gaseous natural gas separated by the first gas-liquid separator is sent on a line through which fluid is sent from the second compander to the first heat exchanger. The method of claim 6,
Wherein the natural gas having passed through the first compressor and the third compressor is in a supercritical fluid state. The method of claim 6,
A second gas-liquid separator that passes through the first compander and separates a part of liquefied natural gas and natural gas remaining in a gaseous state; And
And a fourth valve for controlling the flow rate and pressure of the liquefied natural gas separated by the second gas-liquid separator and sent to the first heat exchanger,
The gaseous natural gas separated by the second gas-liquid separator is sent to the second compander,
Wherein the first heat exchanger comprises: a liquefied natural gas separated by the second gas-liquid separator and passed through the fourth valve; And a fluid that has been separated by the second gas-liquid separator and then passed through the second compander, is used as a refrigerant. The method of claim 8,
A second heat exchanger for self-heat-exchanging liquefied natural gas passing through the first compander;
A fourth compressor for compressing the fluid passing through the second heat exchanger; And
And a sixth cooler for lowering the temperature of the fluid passing through the fourth compressor,
Wherein the second heat exchanger uses the fluid sent from the first compander as a refrigerant to cool the fluid that has passed through the second heat exchanger, the fourth compressor, and the sixth cooler after being sent from the first compander Liquid separator, wherein the second gas-liquid separator is connected to the second gas-liquid separator. A first compressor for compressing natural gas supplied from the outside, a first expander for expanding the fluid that has passed through the first compressor, a second expander for expanding the fluid expanded by the first expander, A first heat exchanger that uses a fluid expanded by the second expansion unit as a refrigerant, a second heat exchanger that compresses a fluid used as a refrigerant in the first heat exchanger, a second expansion unit of the second compander, And a first compressor of the first compander compressing the fluid compressed by the second compressor once and then sending it to the first compressor;
A fuel supply system for supplying a part of the natural gas supplied from the outside to the fuel of the engine;
And a first valve disposed on a line that directs the evaporated gas in the storage tank to the first heat exchanger to regulate the flow rate and pressure of the evaporated gas sent from the storage tank to the first heat exchanger, system; And
The first heat exchanger for cooling the natural gas that has passed through the first compressor using the first compressor, the refrigerant supplied by the refrigerant system, and the evaporation gas supplied from the storage tank, and the first heat exchanger A liquefaction system including an expansion means for expanding a fluid,
The refrigerant system is an open loop,
Wherein the first compressor is used in conjunction with the fuel supply system. The method of claim 10,
The fuel supply system includes:
Further comprising a second compressor for additionally compressing and delivering natural gas compressed by said first compressor to said fuel supply system. The method of claim 11,
A part of the natural gas supplied from the outside is branched at the front end of the first compressor and sent to the low pressure fuel supply system,
Wherein the natural gas compressed by the first compressor and the second compressor is sent to a high pressure fuel supply system. The method of claim 10,
In the liquefaction system,
Further comprising a first gas-liquid separator for separating liquefied natural gas that has passed through the first heat exchanger and the expansion means and natural gas remaining in a gaseous state,
The liquefied natural gas separated by the first gas-liquid separator is sent to the storage tank,
Wherein the natural gas separated by the first gas-liquid separator is sent to the refrigerant system. The method of claim 10,
In the refrigerant system,
Further comprising a second gas-liquid separator for separating the liquefied natural gas liquefied by the first expansion portion and the natural gas remaining in the gaseous state,
The liquefied natural gas separated by the second gas-liquid separator is sent to the first heat exchanger and used as a refrigerant,
Wherein the natural gas separated by the second gas-liquid separator is sent to the second expansion unit. The method of claim 10,
In the refrigerant system,
A second heat exchanger which liquefies the fluid expanded by the first expansion part and sends it to the second gas-liquid separator; And
And a fourth compressor for compressing the fluid passing through the second heat exchanger,
And the second heat exchanger includes a storage tank that uses the fluid that has passed through the first expansion portion as a refrigerant to cool the fluid that has passed through the first expansion portion and then passed through the second heat exchanger and the fourth compressor Ship. A part of the natural gas supplied from outside the system is sent to the low-pressure fuel supply system, the other part is compressed and cooled,
Branching said compressed and cooled natural gas into two streams,
Of the two branched flows, one flow of natural gas is further compressed and cooled and sent to the high-pressure fuel supply system, and the natural gas of another flow (hereinafter referred to as a flow)
(Hereinafter, referred to as 'c') is expanded by expanding one of the branched a flows (hereinafter referred to as 'b flow') and using the expanded b flow and evaporation gas as refrigerant, Flow ") is heat-exchanged,
The c-flow that is heat-exchanged with the b-flow as the refrigerant is expanded and partially or fully liquefied,
Wherein the b stream that has been expanded and exchanged with the c stream is compressed by the energy released when the b stream is expanded and then compressed and cooled again with the natural gas supplied from outside the system. 18. The method of claim 16,
The c-flow heat exchanged with the b-flow as a refrigerant is expanded and partly or wholly liquefied, the liquid phase and the gaseous phase are separated, the separated liquefied natural gas is sent to a storage tank, And again exchanging heat with the refrigerant to cool the c stream. 18. The method of claim 16,
Wherein the liquid phase and the gaseous phase are separated so that the separated liquefied natural gas is heat-exchanged as a refrigerant for cooling the c-flow after the compression and cooling, and the separated natural gas is further expanded so that the c-flow And heat exchanged as a cooling refrigerant. 18. The method of claim 16,
Wherein the expanded b-stream is heat-exchanged as a refrigerant that is compressed and cooled after being heat-exchanged as a refrigerant (hereinafter referred to as 'd-flow') and self-heat-exchanged with the d-flow, followed by cooling the c-flow.

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