KR20160128641A - BOG Re-liquefaction Apparatus and Method for Vessel - Google Patents

Abstract

Disclosed by the present invention is a re-liquefaction apparatus which uses evaporative gas as a cooling fluid in order to re-liquefy evaporative gas generated in a liquefaction gas storage tank installed in a vessel. The evaporative gas re-liquefaction apparatus for a vessel comprises: a plurality of compressors which compresses evaporative gas, discharged from a storage tank, in multiple stages; a heat exchanger which thermally exchanges evaporative gas of being compressed in multiple stages by the compressors and evaporative gas of being discharged from the storage tank; a first expansion means which expands a part of evaporative gas passing through the heat exchanger after being compressed by the compressors; a first intermediate cooler which lowers the temperature of another part of evaporative gas passing through the heat exchanger after being compressed by the compressors; a second expansion means which expands a part of evaporative gas passing through the first intermediate cooler; a second intermediate cooler which lowers another part of evaporative gas passing through the first intermediate cooler; and a third expansion means which expands evaporative gas passing through the second intermediate cooler. The evaporative gas expanded by the first expansion means is used as a refrigerant in the first intermediate cooler and the evaporative gas expanded by the second expansion means is used as a refrigerant in the second intermediate cooler.

Description

BACKGROUND OF THE INVENTION 1. Field of the Invention [0001] The present invention relates to an apparatus and a method for re-

The present invention relates to an apparatus and method for re-liquefying evaporative gas generated in a liquefied gas storage tank applied to a ship.

Natural gas is usually liquefied and transported over a long distance in the form of Liquefied Natural Gas (LNG). Liquefied natural gas is obtained by cooling natural gas at a cryogenic temperature of about -163 ° C at normal pressure. It is very suitable for long distance transportation through the sea because its volume is greatly reduced as compared with the gas state.

Liquefied petroleum gas (LPG) is generally referred to as Liquefied Propane Gas (LPG), and is a natural gas which is cooled at -200 ° C. and discharged at about room temperature And is compressed and liquefied at 7 to 10 atmospheres.

Propane, propylene, butane, butylene, etc. are the major components of petroleum gas. When propane is liquefied at about 15 ° C, the volume is reduced to about 1/260. When butane is liquefied at about 15 ° C, the volume is reduced to about 1/230 For the convenience of storage and transportation, petroleum gas is also used as liquefied natural gas.

The calorific value of liquefied petroleum gas is relatively higher than that of liquefied natural gas. Liquefied petroleum gas is easier to liquefy and vaporize than liquefied natural gas because it contains a relatively large molecular weight component as compared with liquefied natural gas.

Liquefied natural gas, liquefied petroleum gas and other liquefied gases are stored in storage tanks and supplied to the onshore site. However, even if the storage tanks are insulated, there is a limit to completely shut off the external heat. The liquefied gas is continuously vaporized in the storage tank. The liquefied gas vaporized inside the storage tank is referred to as boil-off gas (BOG).

When the pressure of the storage tank becomes equal to or higher than the set pressure due to the generation of evaporative gas, the evaporative gas is discharged to the outside of the storage tank and used as the fuel of the ship or is re-liquefied and returned to the storage tank.

In order to re-liquefy the evaporation gas (hereinafter referred to as " ethane evaporation gas ") containing ethane, ethylene or the like as the main component in the evaporation gas, the ethane evaporation gas must be cooled to approximately -100 deg. It is necessary to further cool and cool more than to re-liquefy the liquefied petroleum gas evaporated gas having the liquefaction point. Therefore, a separate independent cold / hot supply cycle for supplying additional cold heat is added to the liquefied petroleum gas re-liquefaction process and used as the ethane re-liquefaction process. A propylene refrigeration cycle is generally used as the heat and cold supply cycle.

An object of the present invention is to provide an apparatus and a method for liquefying evaporative gas for ship, which re-liquefies evaporative gas such as ethane without a separate independent cooling / heating supply cycle.

According to an aspect of the present invention, there is provided a liquefaction apparatus using a vaporized gas as a cooling fluid to re-liquefy a vapor generated in a liquefied gas storage tank installed in a ship, the apparatus comprising: A plurality of compressors for compressing the evaporating gas in multiple stages; A heat exchanger for exchanging heat between the evaporation gas compressed in multiple stages by the plurality of compressors and the evaporation gas discharged from the storage tank; A first expansion means for expanding a part of the evaporated gas that has been compressed by the plurality of compressors and then passed through the heat exchanger; The first intermediate cooler which is cooled by the plurality of compressors and then lowers the temperature of another part of the evaporated gas that has passed through the heat exchanger; Second expansion means for expanding a part of the evaporated gas that has passed through said first intercooler; A second intermediate cooler for lowering the temperature of another portion of the evaporated gas that has passed through the first interstitial cooler; And third expansion means for expanding the evaporated gas passing through the second intercooler, wherein the evaporated gas expanded by the first expansion means is used as a refrigerant in the first intercooler, and the second expansion means Is used as a refrigerant in the second intercooler. ≪ IMAGE >

The evaporation gas sent to the first intermediate cooler through the first expansion means can be sent to the downstream end of any one of the plurality of compressors and the evaporation gas sent to the second intermediate cooler through the second expansion means The refrigerant discharged from the second intercooler through the second expansion means can be sent to the rear end of any one of the plurality of compressors and the evaporated gas discharged from the first intercooler through the first expansion means is discharged from the second intercooler It can be sent further downstream than the evaporation gas.

The ratio of the evaporation gas to be sent to the first expansion means and the first interstitial cooler can be adjusted according to the degree to which the evaporation gas is to be cooled in the first interstitial cooler and the second expansion means and the second intermediate The ratio of the evaporated gas sent to the chiller can be adjusted according to the degree to which the evaporated gas is to be cooled in the second intercooler.

The partially re-liquefied evaporated gas and the gaseous evaporated gas passing through the third expansion means may be sent to the storage tank together.

The ship evaporating gas re-liquefying apparatus may further include a gas-liquid separator for separating the partially re-liquefied evaporated gas and the remaining evaporated gas in the gaseous state as they pass through the third expansion means.

The gaseous vaporized gas separated by the gas-liquid separator can be sent to the front end of the heat exchanger, and the re-liquefied vaporized gas separated by the gas-liquid separator can be sent to the storage tank.

The gaseous vaporized gas separated by the gas-liquid separator and the re-liquefied vaporized gas may be sent to the storage tank together.

The gaseous vaporized gas separated by the gas-liquid separator and the re-liquefied vaporized gas may be separately sent to the storage tank.

The gaseous vaporized gas separated by the gas-liquid separator can be sent to the lower portion of the storage tank where the liquefied natural gas is filled.

The storage tank may store liquefied gas composed mainly of ethane or ethylene.

The vessel evaporation gas re-liquefier may further include a plurality of coolers installed downstream of the plurality of compressors to lower the temperature of the evaporation gas.

The first expansion means, the second expansion means and the third expansion means may be an expansion valve or an expander.

According to another aspect of the present invention, there is provided a re-liquefaction method using an evaporation gas as a cooling fluid to re-liquefy the evaporation gas generated in a liquefied gas storage tank, The evaporated gas discharged from the storage tank is compressed in multiple stages, the compressed evaporated gas and the evaporated gas discharged from the storage tank are heat-exchanged, and a part of the evaporated gas passing through the heat exchanger is discharged by the first expansion means And another portion of the evaporated gas passing through the heat exchanger is heat-exchanged with the evaporated gas expanded by the first expansion means in the first intermediate cooler to cool the first intermediate cooler, A part of the passing evaporated gas is expanded by the second expansion means and sent to the second intermediate cooler, Another portion of the evaporated gas that has passed through the second intermediate cooler is cooled by heat exchange with the evaporated gas expanded by the second expansion means and the evaporated gas that has passed through the second intermediate cooler is expanded by the third expansion means There is provided a method for re-liquefying a vaporized gas for ship, in which a part is re-liquefied.

The evaporation gas passing through the first expansion means and the evaporation gas passing through the second expansion means can be respectively integrated with the evaporation gas of the similar pressure during the process of multi-stage compression of the evaporation gas discharged from the storage tank.

The evaporated gas expanded by the third expansion means may be sent to the storage tank in a vapor-liquid mixed state.

The evaporated gas re-liquefied in the evaporated gas expanded by the third expansion means can be sent to the storage tank, and the evaporated gas remaining in the gaseous state in the evaporated gas expanded by the third expansion means is discharged from the storage tank The evaporated gas may be heat-exchanged with the compressed evaporated gas.

The evaporated gas re-liquefied in the evaporated gas expanded by the third expansion means can be sent to the storage tank, and the evaporated gas remaining in the gaseous state in the evaporated gas expanded by the third expansion means can be returned to the storage tank Can be sent to the lower part of the storage tank which is a space.

According to the apparatus and method for liquefying the ship vaporized gas for ship according to the present invention, since it is not necessary to provide a separate independent cold / heat supply cycle, the installation cost can be reduced and the evaporating gas such as ethane can be liquefied by self- The re-liquefaction efficiency equivalent to that of the conventional remelting device can be achieved even without a cold / heat supply cycle.

Further, according to the present invention, there is no need to provide a cold / hot supply cycle, so that it is possible to reduce electric power required for driving the cold / hot supply cycle.

FIG. 1 is a schematic block diagram of an evaporative gas re-liquefaction apparatus for a ship according to a first preferred embodiment of the present invention.
2 is a schematic block diagram of an evaporative gas re-liquefaction apparatus for a ship according to a second preferred embodiment of the present invention.
3 is a schematic block diagram of an apparatus for liquefying a ship vaporized gas according to a third preferred embodiment of the present invention.
4 is a schematic block diagram of an evaporative gas re-liquefaction apparatus for a ship according to a fourth preferred embodiment of the present invention.
5 is a schematic configuration diagram of an evaporative gas re-liquefaction apparatus for a ship according to a fifth preferred embodiment of the present invention.

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 apparatus and method for liquefying the vaporized gas for ship according to the present invention can be applied to various applications on ships equipped with liquefied natural gas cargo holds 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.

FIG. 1 is a schematic block diagram of an evaporative gas re-liquefaction apparatus for a ship according to a first preferred embodiment of the present invention.

Referring to FIG. 1, the ship evaporating gas re-liquefying apparatus of the present embodiment includes a plurality of compressors 31, 32, 33, and 34 for compressing the evaporative gas discharged from the storage tank 10 in multiple stages; A heat exchanger (20) for exchanging heat between the evaporated gas compressed in multiple stages by the plurality of compressors (31, 32, 33, 34) and the evaporated gas discharged from the storage tank (10); First expansion means (71) for expanding the evaporated gas that has been compressed by the plurality of compressors (31, 32, 33, 34) and then passed through the heat exchanger (20); A first intermediate cooler 51 which is compressed by the plurality of compressors 31, 32, 33, 34 and then lowers the temperature of the evaporated gas that has passed through the heat exchanger 20; A second expansion means (72) for expanding the evaporated gas which has passed through the first intermediate cooler (51); A second intermediate cooler 52 for lowering the temperature of the evaporated gas that has passed through the first intermediate cooler 51; Third expansion means (73) for expanding the evaporated gas that has passed through the second intercooler (52); And a gas-liquid separator (60) for separating the partially re-liquefied evaporated gas from the remaining evaporated gas in the gaseous state through the third expansion means (73).

The storage tank 10 of the present embodiment stores a liquefied gas such as ethane or ethylene and discharges the evaporated gas generated by vaporization of the liquefied gas by heat transmitted from the outside to the outside when the pressure exceeds a predetermined pressure. In the present embodiment, the liquefied gas is discharged from the storage tank 10, but the liquefied gas may be discharged from the fuel tank storing the liquefied gas to supply the engine with fuel.

The plurality of compressors (31, 32, 33, 34) of the present embodiment compresses the evaporated gas discharged from the storage tank 10 in a multistage manner. In the present embodiment, four compression stages including four compressors have been described, but the number of compressors is not limited.

A plurality of compressors 31, 32, 33, and 34 are provided at the rear end thereof with a plurality of coolers 41, 42, and 34 for lowering the temperature of the evaporated gas as well as the pressure after passing through the compressors 31, 43, and 44, respectively.

The heat exchanger 20 of this embodiment heat-exchanges the evaporated gas compressed by the plurality of compressors 31, 32, 33, 34 with the evaporated gas discharged from the storage tank 10. That is, the evaporated gas compressed by the plurality of compressors 31, 32, 33, 34 and having a high pressure is cooled in the heat exchanger 20 by using the evaporated gas discharged from the storage tank 10 as a refrigerant.

The first expansion means 71 of the present embodiment is provided on a line branched from a line to which the evaporation gas is supplied from the heat exchanger 20 to the first intermediate cooler 51 and is provided with a plurality of compressors 31, , 34, and then expands a part of the evaporated gas that has passed through the heat exchanger (20). The first expansion means 71 may be an expansion valve or an expander.

A part of the evaporated gas that has been compressed by the plurality of compressors 31, 32, 33, and 34 and then passed through the heat exchanger 20 is expanded by the first expansion means 71 to lower the temperature and the pressure. The evaporated gas which has passed through the first expansion means 71 is supplied to the first intermediate cooler 51 and is compressed by the plurality of compressors 31, 32, 33, 34 and then evaporated through the heat exchanger 20 It is used as a refrigerant to lower the temperature of other parts of the gas.

The first interstitial cooler 51 of the present embodiment compresses a part of the evaporated gas that has been compressed by the plurality of compressors 31, 32, 33 and 34 and then passed through the heat exchanger 20 into the first expansion means 71, 32, 33, and 34 and the heat exchanger 20 by lowering the temperature of the evaporation gas that has passed through the plurality of compressors 31, 32, 33, and 34 and the heat exchanger 20.

The evaporated gas whose temperature has been lowered by the first intermediate cooler 51 after passing through the plurality of compressors 31, 32, 33 and 34 and the heat exchanger 20 is supplied to the second expansion means 72 and the second intermediate cooler 52 and the evaporated gas which has been sent to the first intercooler 51 through the first expansion means 71 is supplied to the compressor 32 of any one of the compressors 31, And then sent to the rear end.

The second expansion means 72 of the present embodiment is installed on a line branched from the line from which the evaporation gas is supplied from the first intermediate cooler 51 to the second intermediate cooler 52, 1 intermediate cooler 51 to expand a portion of the cooled evaporated gas. The second expansion means (72) may be an expansion valve or an expander.

Part of the evaporated gas that has passed through the heat exchanger 20 and the first intercooler 51 is expanded by the second expansion means 72 to lower the temperature and the pressure. The evaporated gas that has passed through the second expansion means 72 is supplied to the second intercooler 52 and passes through the heat exchanger 20 and the first intercooler 51 to cool the temperature of the other part of the cooled evaporated gas Used as lowering refrigerant.

The second intercooler 52 of the present embodiment exchanges the cooled evaporated gas with the evaporated gas expanded by the second expansion means 72 through the heat exchanger 20 and the first intercooler 51 The heat exchanger 20 and the first intercooler 51 to lower the temperature of the cooled evaporated gas.

The evaporated gas whose temperature has been lowered by the heat exchanger 20, the first intercooler 51 and the second intercooler 52 is sent to the gas-liquid separator 60 through the third expansion means 73, The evaporated gas that has been sent to the second intercooler 52 through the expansion means 72 is sent to the rear end of any one of the compressors 31, 32, 33, 34.

In the first intermediate cooler 51, the temperature of the evaporated gas primarily cooled in the heat exchanger 20 may be lowered by the evaporated gas discharged from the storage tank 10, but in the second intermediate cooler 52, The evaporated gas supplied to the second intercooler 52 as the refrigerant must be cooled by the first intercooler 51 and the second intercooler 52 after the temperature of the second intercooler 51 is lowered. 51) than the evaporated gas supplied as the refrigerant. That is, the evaporated gas that has passed through the second expansion means 71 is expanded more than the evaporated gas that has passed through the first expansion means 71, 2, the pressure of the evaporating gas passing through the expansion means (72) becomes lower. Therefore, the evaporated gas discharged from the first intercooler 51 is sent to the downstream end of the compressor located further downstream than the evaporated gas discharged from the second intercooler 52. The evaporated gas discharged from the first and second intercoolers 51 and 52 is combined with the evaporated gas of the similar pressure among the evaporated gases subjected to the multi-stage compression process by the plurality of compressors 31, 32, 33, So that a compression process is performed.

On the other hand, the evaporated gas expanded by the first expansion means 71 and the second expansion means 72 is supplied to the first mass air cooler 51 and the second mass air cooler 52 as refrigerant for cooling the evaporation gas The amount of the evaporation gas sent to the first expansion means 71 and the second expansion means 72 can be adjusted according to the degree to which the evaporation gas must be cooled in the first mass air cooler 51 and the second mass air cooler 52. [ The amount can be adjusted. That is, the evaporated gas that has been compressed by the compressors 31, 32, 33, and 34 and passed through the heat exchanger 20 is divided into the first expansion device 71 and the first heavy cooler 51 In order to cool the evaporation gas to a lower temperature in the first mass air cooler 51, the ratio of the evaporation gas to be sent to the first expansion means 71 is increased, and the evaporation gas is reduced in the first mass air cooler 51 To cool down, the ratio of the evaporation gas to the first expansion means (71) is lowered.

The evaporative gas sent from the first massager cooler 51 to the second massager cooler 52 is also supplied to the second massager cooler 52 as well as the evaporative gas sent from the heat exchanger 20 to the first massager cooler 51. [ The first expansion means 71 and the second expansion means 72 are provided to send a larger proportion of the evaporation gas to the second expansion means 72 to cool the evaporation gas to a lower temperature and to lessen the evaporation gas in the second mass cooler 52, Thereby reducing the ratio of the evaporated gas to the gas.

Although the present embodiment has been described by way of example in which two intermediate coolers 51 and 52 and two expansion means 71 and 72 provided at the front ends of the respective intermediate coolers 51 and 52 are included, The number of expansion means installed in front of the cooler and the intermediate cooler may be changed. The intercoolers 51 and 52 of the present embodiment may use a ship interim cooler as shown in Fig. 1, or a general heat exchanger may be used.

The third expansion means (73) of the present embodiment expands the evaporation gas that has passed through the first intermediate cooler (51) and the second intermediate cooler (52) to approximately atmospheric pressure.

The gas-liquid separator 60 of this embodiment separates the partially re-liquefied evaporated gas from the evaporated gas remaining in the gaseous state without being liquefied while passing through the third expansion means 73. The evaporated gas in the gaseous state separated by the gas-liquid separator 60 is sent to the front end of the heat exchanger 20 to be re-liquefied together with the evaporated gas discharged from the storage tank 10, The re-liquefied evaporated gas separated by the evaporator is returned to the storage tank 10. When the evaporation gas of this embodiment is discharged from the fuel tank, the re-liquefied evaporated gas is sent to the fuel tank.

Referring to FIG. 1, the flow of the evaporative gas by the evaporative gas re-liquefying apparatus for ship according to this embodiment will be described as follows.

The evaporated gas discharged from the storage tank 10 is compressed by the plurality of compressors 31, 32, 33, 34 after passing through the heat exchanger 20. [ The pressure of the evaporated gas compressed by the plurality of compressors 31, 32, 33, 34 is approximately 40 bar to 100 bar, preferably approximately 80 bar. The evaporated gas compressed by the plurality of compressors 31, 32, 33, and 34 becomes a supercritical fluid state in a third state in which there is no distinction between gas and liquid.

The evaporated gas that has passed through the plurality of compressors 31, 32, 33 and 34 passes through the heat exchanger 20, the first intercooler 51 and the second intercooler 52 and flows into the third expansion means 73, , The pressure is maintained approximately equal to the supercritical fluid state. The evaporated gas that has passed through the plurality of compressors 31, 32, 33, and 34 is cooled down each time it passes through the heat exchanger 20, the first intercooler 51, and the second intercooler 52 The pressure may be lowered each time it passes through the heat exchanger 20, the first intercooler 51, and the second intercooler 52 according to the operation method of the process, so that the heat exchanger 20, Liquid mixed state until it passes through the first intermediate expansion valve 51 and the second intermediate cooler 52 and passes through the third expansion means 73, or may be in a liquid state.

The evaporated gas that has passed through the plurality of compressors 31, 32, 33, and 34 is again sent to the heat exchanger 20 to be heat-exchanged with the evaporated gas discharged from the storage tank 10. A portion of the evaporation gas that has passed through the plurality of compressors 31, 32, 33 and 34 and the heat exchanger 20 is sent to the first expansion means 71 and the other portion is sent to the first inter- Loses. The evaporated gas sent to the first expansion means 71 is expanded and sent to the first intermediate cooler 51 after the temperature and the pressure are lowered and is sent to the first intermediate cooler 51 after passing through the heat exchanger 20 The evaporation gas is heat-exchanged with the evaporation gas that has passed through the first expansion means (71) to lower the temperature.

The evaporated gas, which is partially diverted after passing through the heat exchanger 20 and sent to the first expansion means 71, can be expanded by the first expansion means 71 to become a vapor-liquid mixed state. The evaporated gas expanded by the first expansion means (71) and brought into the vapor-liquid mixed state can be in a gaseous state after being heat-exchanged in the first intermediate cooler (51).

A part of the evaporated gas which has been exchanged with the evaporated gas passing through the first expansion means 71 in the first interstitial cooler 51 is sent to the second expansion means 72 and the other part is sent to the second intermediate cooler 52, Lt; / RTI > The evaporated gas sent to the second expansion means 72 is expanded and sent to the second intercooler 52 after the temperature and the pressure are lowered. After passing through the first intercooler 51, the second intercooler 52, Is heat-exchanged with the evaporation gas that has passed through the second expansion means (72), so that the temperature is lowered.

A portion of the evaporated gas that has passed through the first intercooler 51 and is then sent to the second expansion means 72 is partially branched after passing through the heat exchanger 20 and is sent to the first expansion means 71 It can be expanded by the second expansion means 72 to become a gas-liquid mixed state, similarly to the evaporation gas. The evaporated gas expanded by the second expansion means (72) and brought into a vapor-liquid mixed state can be in a gaseous state after being heat-exchanged in the second intermediate cooler (52).

The temperature of the evaporation gas which has passed through the second expansion means 72 in the second intermediate cooler 52 and exchanged with the heat of the evaporation gas is lowered to a substantially normal pressure by the third expansion means 73 and a part thereof is re-liquefied. The evaporated gas that has passed through the third expansion means 73 is sent to the gas-liquid separator 60 to separate the re-liquefied evaporated gas and the gaseous evaporated gas, and the re-liquefied evaporated gas is sent to the storage tank 10 , The gaseous vaporized gas is sent to the front end of the heat exchanger (20).

The evaporating gas re-liquefying apparatus for a ship of the present embodiment is characterized in that the evaporation gas expanded by the first expansion means (71) and the evaporation gas expanded by the second expansion means (72) are used as the refrigerant, The evaporation gas can be re-liquefied without a separate cold / heat supply cycle.

Further, in the remelting apparatus to which the conventional additional cold / heat supply cycle is added, approximately 2.4 kW of power is consumed to recover the heat of 1 kW, whereas in the evaporative gas re-liquefying apparatus of this embodiment, It can be seen that approximately 1.7 kW of power is consumed to recover the energy consumed in driving the remelting device.

2 is a schematic block diagram of an evaporative gas re-liquefaction apparatus for a ship according to a second preferred embodiment of the present invention.

The evaporative gas re-liquefying apparatus for a ship according to the second embodiment shown in Fig. 2 is different from the evaporating gas re-liquefier for ship according to the first embodiment shown in Fig. 1 in that the re-liquefied evaporated gas separated by the gas- And the gas is sent to the storage tank together with the evaporating gas. In the following, the difference will be mainly described. A detailed description of the same components as those of the vaporizing-gas re-liquefaction apparatus for a ship of the first embodiment will be omitted.

Referring to FIG. 2, the evaporating gas re-liquefaction apparatus for a ship of the present embodiment includes a plurality of compressors 31, 32, 33, and 34 as in the first embodiment; A heat exchanger (20); A first expansion means (71); A first interstitial cooler 51; A second expansion means (72); A second intercooler 52; A third expansion means (73); And a gas-liquid separator (60).

As in the first embodiment, the storage tank 10 of the present embodiment stores liquefied gas such as ethane or ethylene, and when the evaporation gas generated by vaporization of the liquefied gas by heat transmitted from the outside is at a certain pressure or more, .

The plurality of compressors 31, 32, 33, and 34 of this embodiment compresses the evaporated gas discharged from the storage tank 10 in a multistage manner as in the first embodiment. A plurality of coolers 41, 42, 43, and 44 may be installed at the rear ends of the plurality of compressors 31, 32, 33, and 34, respectively.

The heat exchanger 20 of the present embodiment heat-exchanges the evaporated gas compressed by the plurality of compressors 31, 32, 33, and 34 with the evaporated gas discharged from the storage tank 10 as in the first embodiment .

The first expansion means 71 of the present embodiment is provided on a line branched from a line to which evaporative gas is supplied from the heat exchanger 20 to the first intermediate cooler 51 in the same manner as the first embodiment, Compresses by the compressors (31, 32, 33, 34), and then expands a part of the evaporated gas that has passed through the heat exchanger (20).

The first inter-cooler 51 of the present embodiment is configured such that a part of the evaporated gas that has been compressed by the plurality of compressors 31, 32, 33, 34 and then passed through the heat exchanger 20, The evaporation gas expanded by the first expansion means 71 is heat-exchanged to lower the temperature of the evaporation gas which has passed through the plurality of compressors 31, 32, 33, 34 and the heat exchanger 20.

The second expansion means 72 of the present embodiment is provided on a line branched from the line from which the evaporation gas is supplied from the first interi cooler 51 to the second interi cooler 52 as in the first embodiment, Passes through the heat exchanger (20) and the first intermediate cooler (51) and expands a part of the cooled evaporated gas.

The second intercooler 52 of the present embodiment is configured such that the refrigerant vapor that has passed through the heat exchanger 20 and the first intercooler 51 and is cooled by the second expansion means 72 Exchanges heat with the expanded evaporated gas, passes through the heat exchanger 20 and the first intercooler 51 and further reduces the temperature of the cooled evaporated gas.

The evaporated gas discharged from the first intercooler 51 is sent to the downstream end of the compressor positioned further downstream than the evaporated gas discharged from the second intercooler 52 as in the first embodiment.

In order to cool the evaporation gas to a lower temperature in the first mass air cooler 51 as in the first embodiment, the proportion of the evaporation gas to be sent to the first expansion means 71 is increased, The ratio of the evaporation gas to the first expansion means 71 is lowered.

The evaporative gas sent from the first massager cooler 51 to the second massager cooler 52 is also supplied to the second massager cooler 52 as well as the evaporative gas sent from the heat exchanger 20 to the first massager cooler 51. [ The first expansion means 71 and the second expansion means 72 are provided to send a larger proportion of the evaporation gas to the second expansion means 72 to cool the evaporation gas to a lower temperature and to lessen the evaporation gas in the second mass cooler 52, Thereby reducing the ratio of the evaporated gas to the gas.

The third expansion means 73 of the present embodiment expands the evaporation gas that has passed through the first intermediate cooler 51 and the second intermediate cooler 52 to substantially atmospheric pressure as in the first embodiment.

The gas-liquid separator 60 of this embodiment separates the partially re-liquefied evaporated gas while passing through the third expansion means 73 and the evaporated gas that remains in the gaseous state without being liquefied, as in the first embodiment.

However, unlike the first embodiment, the gaseous vaporized gas separated by the gas-liquid separator 60 of this embodiment is sent to the storage tank 10 together with the re-liquefied vaporized gas. The evaporated gas in the gaseous state sent to the storage tank 10 is sent to the heat exchanger 20 together with the evaporated gas in the storage tank 10 to be subjected to the liquefaction process again.

Referring to FIG. 2, the flow of evaporative gas by the evaporative gas re-liquefying apparatus for ship according to this embodiment will be described as follows.

The evaporated gas discharged from the storage tank 10 is compressed by a plurality of compressors 31, 32, 33, and 34 after passing through the heat exchanger 20 as in the first embodiment.

The evaporated gas that has passed through the plurality of compressors 31, 32, 33, and 34 is sent to the heat exchanger 20 again for heat exchange with the evaporated gas discharged from the storage tank 10 as in the first embodiment. A portion of the evaporation gas that has passed through the plurality of compressors 31, 32, 33 and 34 and the heat exchanger 20 is sent to the first expansion means 71 and the other portion is sent to the first inter- Loses. The evaporated gas sent to the first expansion means 71 is expanded and sent to the first intermediate cooler 51 after the temperature and the pressure are lowered and is sent to the first intermediate cooler 51 after passing through the heat exchanger 20 The evaporation gas is heat-exchanged with the evaporation gas that has passed through the first expansion means (71) to lower the temperature.

As in the first embodiment, a part of the evaporated gas that has been heat-exchanged with the evaporated gas that has passed through the first expansion means 71 in the first interstitial cooler 51 is sent to the second expansion means 72, And is sent to the second intercooler 52. The evaporated gas sent to the second expansion means 72 is expanded and sent to the second intercooler 52 after the temperature and the pressure are lowered. After passing through the first intercooler 51, the second intercooler 52, Is heat-exchanged with the evaporation gas that has passed through the second expansion means (72), so that the temperature is lowered.

As in the first embodiment, the temperature of the evaporation gas that has passed through the second expansion means 72 in the second intermediate cooler 52 is lowered to substantially normal pressure by the third expansion means 73, Lt; / RTI > The evaporated gas that has passed through the third expansion means (73) is sent to the gas-liquid separator (60), and the re-liquefied evaporated gas and the gaseous evaporated gas are separated.

However, unlike the first embodiment, both the gaseous vapor state and the liquid state vaporized gas separated by the gas-liquid separator 60 of this embodiment are all sent to the storage tank 10.

3 is a schematic block diagram of an apparatus for liquefying a ship vaporized gas according to a third preferred embodiment of the present invention.

The apparatus for liquefying vaporized marine vessels of the third embodiment shown in Fig. 3 differs from the apparatus for liquefying marine vessels for liquefying marine vessels of the first embodiment shown in Fig. 1 in that vaporized gas is sent to the storage tank, And there is a difference in that the evaporation gas in the gaseous state is separated from the re-liquefied evaporated gas and sent separately to the storage tank, as compared with the evaporative-gas re-liquefaction apparatus for a ship of the second embodiment shown in Fig. The differences are mainly described below. The detailed description of the same components as those of the evaporation gas re-liquefaction apparatus for marine vessels of the first and second embodiments will be omitted.

Referring to FIG. 3, the evaporating gas re-liquefying apparatus for a ship of the present embodiment includes a plurality of compressors 31, 32, 33, and 34 as in the first and second embodiments; A heat exchanger (20); A first expansion means (71); A first interstitial cooler 51; A second expansion means (72); A second intercooler 52; A third expansion means (73); And a gas-liquid separator (60).

As in the first and second embodiments, the storage tank 10 of this embodiment stores liquefied gases such as ethane and ethylene, and supplies the evaporated gas generated by vaporization of liquefied gas by external heat to a constant If the pressure is exceeded, discharge it to the outside.

The plurality of compressors 31, 32, 33, and 34 of this embodiment compresses the evaporated gas discharged from the storage tank 10 in a multistage manner as in the first and second embodiments. A plurality of coolers 41, 42, 43, and 44 may be installed at the rear ends of the plurality of compressors 31, 32, 33, and 34, respectively.

The heat exchanger 20 of the present embodiment is arranged so that the evaporated gas compressed by the compressors 31, 32, 33, and 34 is discharged from the storage tank 10 as in the first and second embodiments Heat exchange with evaporative gas.

The first expansion means 71 of the present embodiment is arranged so as to extend from the heat exchanger 20 to the first intermediate cooler 51 on a line that branches from the line to which the evaporation gas is supplied as in the first and second embodiments And is expanded by a part of the evaporated gas passing through the heat exchanger 20 after being compressed by the plurality of compressors 31, 32, 33, 34.

The first intercooler 51 of the present embodiment is the same as the first and second embodiments except that it is compressed by a plurality of compressors 31, 32, 33, 34 and then evaporated through the heat exchanger 20 A part of the gas is heat-exchanged with the evaporated gas expanded by the first expansion means 71 to lower the temperature of the evaporated gas that has passed through the plurality of compressors 31, 32, 33, 34 and the heat exchanger 20.

The second expansion means 72 of the present embodiment is similar to the first and second embodiments in that the line extending from the line from which the evaporation gas is supplied from the first intermittent cooler 51 to the second intermittent cooler 52 To expand a part of the cooled evaporated gas through the heat exchanger (20) and the first intermediate cooler (51).

The second intercooler 52 of the present embodiment is arranged so that the cooled evaporated gas passes through the heat exchanger 20 and the first intercooler 51 and flows through the second expansion means Exchanges heat with the evaporated gas expanded by the heat exchanger (72), passes through the heat exchanger (20) and the first intercooler (51) and further lowers the temperature of the cooled evaporated gas.

The evaporated gas discharged from the first intercooler 51 is sent to the downstream end of the compressor positioned further downstream than the evaporated gas discharged from the second intercooler 52 as in the first and second embodiments do.

As in the first and second embodiments, in order to cool the evaporation gas to a lower temperature in the first mass air cooler 51, the ratio of the evaporation gas to be sent to the first expansion means 71 is increased, In order to cool the evaporated gas in the heavy angle cooler 51 to a lesser extent, the ratio of the evaporated gas to the first expansion means 71 is lowered.

The evaporative gas sent from the first massager cooler 51 to the second massager cooler 52 is also supplied to the second massager cooler 52 as well as the evaporative gas sent from the heat exchanger 20 to the first massager cooler 51. [ The first expansion means 71 and the second expansion means 72 are provided to send a larger proportion of the evaporation gas to the second expansion means 72 to cool the evaporation gas to a lower temperature and to lessen the evaporation gas in the second mass cooler 52, Thereby reducing the ratio of the evaporated gas to the gas.

The third expansion means 73 of the present embodiment expands the evaporation gas that has passed through the first intermediate cooler 51 and the second intermediate cooler 52 to substantially atmospheric pressure similarly to the first and second embodiments .

The gas-liquid separator 60 of this embodiment separates the partially re-liquefied evaporated gas while passing through the third expansion means 73 and the evaporated gas that remains in the gaseous state without liquefaction as in the first and second embodiments do.

However, unlike the first embodiment, the gaseous vaporized gas separated by the gas-liquid separator 60 of this embodiment is sent to the storage tank 10, and unlike the second embodiment, The gas is not sent to the storage tank 10 together with the re-liquefied evaporated gas, but is separated from the re-liquefied evaporated gas and sent to the storage tank 10 separately.

Referring to FIG. 3, the flow of the evaporative gas by the evaporative gas re-liquefying apparatus for ship according to the present embodiment will be described as follows.

The evaporated gas discharged from the storage tank 10 is compressed by the plurality of compressors 31, 32, 33, and 34 after passing through the heat exchanger 20, as in the first and second embodiments.

The evaporated gas that has passed through the plurality of compressors 31, 32, 33, and 34 is sent again to the heat exchanger 20 as in the first and second embodiments, Respectively. A portion of the evaporation gas that has passed through the plurality of compressors 31, 32, 33 and 34 and the heat exchanger 20 is sent to the first expansion means 71 and the other portion is sent to the first inter- Loses. The evaporated gas sent to the first expansion means 71 is expanded and sent to the first intermediate cooler 51 after the temperature and pressure are lowered and is sent to the first intermediate cooler 51 after passing through the heat exchanger 20 The evaporation gas is heat-exchanged with the evaporation gas that has passed through the first expansion means (71) to lower the temperature.

As in the first and second embodiments, a portion of the evaporated gas that has been heat-exchanged with the evaporated gas that has passed through the first expansion means 71 in the first interstitial cooler 51 is sent to the second expansion means 72 And the other part is sent to the second intercooler 52. The evaporated gas sent to the second expansion means 72 is expanded and sent to the second intercooler 52 after the temperature and the pressure are lowered. After passing through the first intercooler 51, the second intercooler 52, Is heat-exchanged with the evaporation gas that has passed through the second expansion means (72), so that the temperature is lowered.

As in the first and second embodiments, the temperature of the evaporation gas that has passed through the second expansion means 72 in the second intermediate cooler 52 and has been heat-exchanged with the other is expanded by the third expansion means 73 The pressure is lowered to about atmospheric pressure, and a part is re-liquefied. The evaporated gas that has passed through the third expansion means (73) is sent to the gas-liquid separator (60), and the re-liquefied evaporated gas and the gaseous evaporated gas are separated.

However, unlike the first embodiment, both the gas-state evaporative gas and the liquid-state evaporative gas separated by the gas-liquid separator 60 of this embodiment are sent to the storage tank 10, Otherwise, the gaseous vaporized gas separated by the gas-liquid separator 60 of this embodiment is separated from the liquid-state vaporized gas and sent to the storage tank 10 separately.

4 is a schematic block diagram of an evaporative gas re-liquefaction apparatus for a ship according to a fourth preferred embodiment of the present invention.

4 is different from the apparatus for liquefying the ship evaporative gas according to the first embodiment shown in Fig. 1 in that the gaseous evaporative gas is sent to the storage tank, And there is a difference in that the evaporated gas in the gaseous state is sent to the lower portion of the storage tank as compared with the evaporative gas re-liquefaction apparatus for ship in the third embodiment shown in Fig. The differences are mainly described below. The detailed description of the same components as those of the evaporation gas re-liquefaction apparatus for marine vessels of the first and third embodiments will be omitted.

Referring to FIG. 4, the evaporation gas re-liquefying apparatus for a ship of the present embodiment includes a plurality of compressors 31, 32, 33, and 34 as in the first and third embodiments; A heat exchanger (20); A first expansion means (71); A first interstitial cooler 51; A second expansion means (72); A second intercooler 52; A third expansion means (73); And a gas-liquid separator (60).

As in the first and third embodiments, the storage tank 10 of this embodiment stores liquefied gas such as ethane, ethylene, etc., and supplies the evaporated gas generated by vaporization of the liquefied gas by external heat to a constant If the pressure is exceeded, discharge it to the outside.

The plurality of compressors 31, 32, 33, and 34 of the present embodiment compresses the evaporated gas discharged from the storage tank 10 in a multistage manner as in the first and third embodiments. A plurality of coolers 41, 42, 43, and 44 may be installed at the rear ends of the plurality of compressors 31, 32, 33, and 34, respectively.

The heat exchanger 20 of the present embodiment is arranged so that the evaporated gas compressed by the compressors 31, 32, 33, and 34 is discharged from the storage tank 10 as in the first and third embodiments Heat exchange with evaporative gas.

The first expansion means 71 of the present embodiment is arranged so as to extend from the heat exchanger 20 to the first intermediate cooler 51 on a line branched from the line to which the evaporation gas is supplied as in the first embodiment and the third embodiment And is expanded by a part of the evaporated gas passing through the heat exchanger 20 after being compressed by the plurality of compressors 31, 32, 33, 34.

The first intermediate cooler 51 of the present embodiment is compressed by the plurality of compressors 31, 32, 33, and 34 and then evaporated through the heat exchanger 20 as in the first and third embodiments A part of the gas is heat-exchanged with the evaporated gas expanded by the first expansion means 71 to lower the temperature of the evaporated gas that has passed through the plurality of compressors 31, 32, 33, 34 and the heat exchanger 20.

The second expansion means 72 of the present embodiment is similar to the first and third embodiments in that the line extending from the line from which the evaporation gas is supplied from the first intermittent cooler 51 to the second intermittent cooler 52 To expand a part of the cooled evaporated gas through the heat exchanger (20) and the first intermediate cooler (51).

The second intercooler 52 of the present embodiment is arranged so as to pass the cooled evaporated gas through the heat exchanger 20 and the first intercooler 51 to the second expansion means Exchanges heat with the evaporated gas expanded by the heat exchanger (72), passes through the heat exchanger (20) and the first intercooler (51) and further lowers the temperature of the cooled evaporated gas.

The evaporated gas discharged from the first intercooler 51 is sent to the downstream end of the compressor positioned further downstream than the evaporated gas discharged from the second intercooler 52 as in the first and third embodiments do.

In order to cool the evaporation gas to a lower temperature in the first mass air cooler 51 as in the first and third embodiments, the proportion of the evaporation gas to be sent to the first expansion means 71 is increased, In order to cool the evaporated gas in the heavy angle cooler 51 to a lesser extent, the ratio of the evaporated gas to the first expansion means 71 is lowered.

The evaporative gas sent from the first massager cooler 51 to the second massager cooler 52 is also supplied to the second massager cooler 52 as well as the evaporative gas sent from the heat exchanger 20 to the first massager cooler 51. [ The first expansion means 71 and the second expansion means 72 are provided to send a larger proportion of the evaporation gas to the second expansion means 72 to cool the evaporation gas to a lower temperature and to lessen the evaporation gas in the second mass cooler 52, Thereby reducing the ratio of the evaporated gas to the gas.

The third expansion means 73 of the present embodiment expands the evaporation gas that has passed through the first intermediate cooler 51 and the second intermediate cooler 52 to substantially atmospheric pressure as in the first and third embodiments .

The gas-liquid separator 60 of this embodiment separates the partially re-liquefied evaporated gas while passing through the third expansion means 73 and the evaporated gas that remains in the gaseous state without liquefaction as in the first and third embodiments do.

However, unlike the first embodiment, both the gas-state evaporative gas and the liquid-state evaporative gas separated by the gas-liquid separator 60 of this embodiment are sent to the storage tank 10, Alternatively, the gaseous vaporized gas separated by the gas-liquid separator 60 of the present embodiment is not sent to the upper portion of the storage tank 10, but is sent to the lower portion of the storage tank 10, which is a space filled with liquefied natural gas.

When the gaseous vaporized gas separated by the gas-liquid separator 60 is sent to the lower portion of the storage tank 10, the temperature of the gaseous vaporized gas is lowered by the cooling of the liquefied natural gas or a part of the vaporized gas is liquefied So that the re-liquefaction efficiency can be increased. The liquefied natural gas in the storage tank 10 has a lower temperature than that of the portion having a higher water level. Therefore, when the gaseous evaporated gas is sent to the lower portion of the storage tank 10, It is preferable to send it to the lowermost part of the body 10.

Referring to FIG. 4, the flow of the evaporative gas by the evaporative gas re-liquefying apparatus for ship according to this embodiment will be described as follows.

The evaporated gas discharged from the storage tank 10 is compressed by the plurality of compressors 31, 32, 33, and 34 after passing through the heat exchanger 20, as in the first and third embodiments.

The evaporated gas that has passed through the plurality of compressors 31, 32, 33, and 34 is sent to the heat exchanger 20 again as in the first and third embodiments, and the evaporated gas discharged from the storage tank 10 Respectively. A portion of the evaporation gas that has passed through the plurality of compressors 31, 32, 33 and 34 and the heat exchanger 20 is sent to the first expansion means 71 and the other portion is sent to the first inter- Loses. The evaporated gas sent to the first expansion means 71 is expanded and sent to the first intermediate cooler 51 after the temperature and the pressure are lowered and is sent to the first intermediate cooler 51 after passing through the heat exchanger 20 The evaporation gas is heat-exchanged with the evaporation gas that has passed through the first expansion means (71) to lower the temperature.

As in the first and third embodiments, a portion of the evaporated gas that has been heat-exchanged with the evaporated gas that has passed through the first expansion means 71 in the first interstitial cooler 51 is sent to the second expansion means 72 And the other part is sent to the second intercooler 52. The evaporated gas sent to the second expansion means 72 is expanded and sent to the second intercooler 52 after the temperature and the pressure are lowered. After passing through the first intercooler 51, the second intercooler 52, Is heat-exchanged with the evaporation gas that has passed through the second expansion means (72), so that the temperature is lowered.

As in the first and third embodiments, the temperature of the evaporation gas that has passed through the second expansion means 72 in the second intermediate cooler 52 and is heat-exchanged with the third expansion means 72 is lowered by the third expansion means 73 The pressure is lowered to about atmospheric pressure, and a part is re-liquefied. The evaporated gas that has passed through the third expansion means (73) is sent to the gas-liquid separator (60), and the re-liquefied evaporated gas and the gaseous evaporated gas are separated.

However, unlike the first embodiment, both the gas-state evaporative gas and the liquid-state evaporative gas separated by the gas-liquid separator 60 of this embodiment are sent to the storage tank 10, Alternatively, the gaseous vaporized gas separated by the gas-liquid separator 60 of the present embodiment is not sent to the upper portion of the storage tank 10, but is sent to the lower portion of the storage tank 10, which is a space filled with liquefied natural gas.

5 is a schematic configuration diagram of an evaporative gas re-liquefaction apparatus for a ship according to a fifth preferred embodiment of the present invention.

5 differs from the apparatus for liquefying a vaporized gas for ship according to the first embodiment shown in Fig. 1 in that it does not include a gas-liquid separator, and in the following description, Explain the difference mainly. A detailed description of the same components as those of the vaporizing-gas re-liquefaction apparatus for a ship of the first embodiment will be omitted.

Referring to FIG. 5, the evaporating gas re-liquefying apparatus for a ship of the present embodiment includes a plurality of compressors 31, 32, 33, and 34 as in the first embodiment; A heat exchanger (20); A first expansion means (71); A first interstitial cooler 51; A second expansion means (72); A second intercooler 52; And a third expansion means (73). However, unlike the first embodiment, the evaporative gas re-liquefying apparatus for vessels of the present embodiment does not include the gas-liquid separator 60.

As in the first embodiment, the storage tank 10 of the present embodiment stores liquefied gas such as ethane or ethylene, and when the evaporation gas generated by vaporization of the liquefied gas by heat transmitted from the outside is at a certain pressure or more, .

The plurality of compressors 31, 32, 33, and 34 of this embodiment compresses the evaporated gas discharged from the storage tank 10 in a multistage manner as in the first embodiment. A plurality of coolers 41, 42, 43, and 44 may be installed at the rear ends of the plurality of compressors 31, 32, 33, and 34, respectively.

The heat exchanger 20 of the present embodiment heat-exchanges the evaporated gas compressed by the plurality of compressors 31, 32, 33, and 34 with the evaporated gas discharged from the storage tank 10 as in the first embodiment .

The first expansion means 71 of the present embodiment is provided on a line branched from a line to which evaporative gas is supplied from the heat exchanger 20 to the first intermediate cooler 51 in the same manner as the first embodiment, Compresses by the compressors (31, 32, 33, 34), and then expands a part of the evaporated gas that has passed through the heat exchanger (20).

The first inter-cooler 51 of the present embodiment is configured such that a part of the evaporated gas that has been compressed by the plurality of compressors 31, 32, 33, 34 and then passed through the heat exchanger 20, The evaporation gas expanded by the first expansion means 71 is heat-exchanged to lower the temperature of the evaporation gas which has passed through the plurality of compressors 31, 32, 33, 34 and the heat exchanger 20.

The second expansion means 72 of the present embodiment is provided on a line branched from the line from which the evaporation gas is supplied from the first interi cooler 51 to the second interi cooler 52 as in the first embodiment, Passes through the heat exchanger (20) and the first intermediate cooler (51) and expands a part of the cooled evaporated gas.

The second intercooler 52 of the present embodiment is configured such that the refrigerant vapor that has passed through the heat exchanger 20 and the first intercooler 51 and is cooled by the second expansion means 72 Exchanges heat with the expanded evaporated gas, passes through the heat exchanger 20 and the first intercooler 51 and further reduces the temperature of the cooled evaporated gas.

The evaporated gas discharged from the first intercooler 51 is sent to the downstream end of the compressor positioned further downstream than the evaporated gas discharged from the second intercooler 52 as in the first embodiment.

In order to cool the evaporation gas to a lower temperature in the first mass air cooler 51 as in the first embodiment, the proportion of the evaporation gas to be sent to the first expansion means 71 is increased, The ratio of the evaporation gas to the first expansion means 71 is lowered.

The evaporative gas sent from the first massager cooler 51 to the second massager cooler 52 is also supplied to the second massager cooler 52 as well as the evaporative gas sent from the heat exchanger 20 to the first massager cooler 51. [ The first expansion means 71 and the second expansion means 72 are provided to send a larger proportion of the evaporation gas to the second expansion means 72 to cool the evaporation gas to a lower temperature and to lessen the evaporation gas in the second mass cooler 52, Thereby reducing the ratio of the evaporated gas to the gas.

The third expansion means 73 of the present embodiment expands the evaporation gas that has passed through the first intermediate cooler 51 and the second intermediate cooler 52 to substantially atmospheric pressure as in the first embodiment.

However, since the vessel liquefaction apparatus for liquefied gas for ship according to the present embodiment does not include the gas-liquid separator 60, the evaporated gas passing through the third expansion means 73 and partially re-liquefied and the gaseous evaporated gas , And is sent to the storage tank 10 together in a mixed state.

When the gaseous evaporated gas is not sent to the front end of the heat exchanger 20 but is sent to the storage tank 10 as in the second to fifth embodiments, when the storage tank 10 is a pressurized tank It is advantageous that the evaporated gas can be smoothly discharged from the storage tank 10 by the pressure inside the storage tank 10 without the operation of a separate pump.

Referring to FIG. 5, the flow of the evaporative gas by the evaporative gas re-liquefying apparatus for ship according to the present embodiment will be described as follows.

The evaporated gas discharged from the storage tank 10 is compressed by a plurality of compressors 31, 32, 33, and 34 after passing through the heat exchanger 20 as in the first embodiment.

The evaporated gas that has passed through the plurality of compressors 31, 32, 33, and 34 is sent to the heat exchanger 20 again for heat exchange with the evaporated gas discharged from the storage tank 10 as in the first embodiment. A portion of the evaporation gas that has passed through the plurality of compressors 31, 32, 33 and 34 and the heat exchanger 20 is sent to the first expansion means 71 and the other portion is sent to the first inter- Loses. The evaporated gas sent to the first expansion means 71 is expanded and sent to the first intermediate cooler 51 after the temperature and the pressure are lowered and is sent to the first intermediate cooler 51 after passing through the heat exchanger 20 The evaporation gas is heat-exchanged with the evaporation gas that has passed through the first expansion means (71) to lower the temperature.

As in the first embodiment, a part of the evaporated gas that has been heat-exchanged with the evaporated gas that has passed through the first expansion means 71 in the first interstitial cooler 51 is sent to the second expansion means 72, And is sent to the second intercooler 52. The evaporated gas sent to the second expansion means 72 is expanded and sent to the second intercooler 52 after the temperature and the pressure are lowered. After passing through the first intercooler 51, the second intercooler 52, Is heat-exchanged with the evaporation gas that has passed through the second expansion means (72), so that the temperature is lowered.

As in the first embodiment, the temperature of the evaporation gas that has passed through the second expansion means 72 in the second intermediate cooler 52 is lowered to substantially normal pressure by the third expansion means 73, Lt; / RTI > However, unlike the first embodiment, the evaporated gas that has passed through the third expansion means 73 is sent to the storage tank 10 in a vapor-liquid mixed state.

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: Heat exchanger
31, 32, 33, 34: compressors 41, 42, 43, 44:
51, 52: intercooler 60: gas-liquid separator
71, 72, 73: expansion means

Claims (17)

A re-liquefying apparatus using evaporation gas as a cooling fluid for re-liquefaction of evaporation gas generated in a liquefied gas storage tank installed in a ship,
A plurality of compressors for compressing the evaporated gas discharged from the storage tank in a multistage manner;
A heat exchanger for exchanging heat between the evaporation gas compressed in multiple stages by the plurality of compressors and the evaporation gas discharged from the storage tank;
A first expansion means for expanding a part of the evaporated gas that has been compressed by the plurality of compressors and then passed through the heat exchanger;
The first intermediate cooler which is cooled by the plurality of compressors and then lowers the temperature of another part of the evaporated gas that has passed through the heat exchanger;
Second expansion means for expanding a part of the evaporated gas that has passed through said first intercooler;
A second intermediate cooler for lowering the temperature of another portion of the evaporated gas that has passed through the first interstitial cooler; And
And third expansion means for expanding the evaporated gas passing through the second intercooler,
The evaporated gas expanded by the first expansion means is used as a refrigerant in the first intermediate cooler,
And the evaporated gas expanded by the second expansion means is used as a refrigerant in the second intermediate cooler. The method according to claim 1,
The evaporation gas sent to the first massager cooler through the first expansion means is sent to the downstream end of one of the plurality of compressors,
The evaporation gas sent to the second intermediate cooler through the second expansion means is sent to the downstream end of one of the plurality of compressors,
Wherein the evaporation gas discharged from the first intermediate cooler through the first expansion means is sent further downstream than the evaporated gas discharged from the second intermediate cooler through the second expansion means, . The method according to claim 1,
The ratio of the evaporation gas to be sent to the first expansion means and to the first intercooler is adjusted according to the extent to which the evaporation gas is to be cooled in the first intercooler,
Wherein the ratio of the evaporation gas to be sent to the second expansion means and the second intercooler is adjusted according to the extent to which the evaporation gas is to be cooled in the second intercooler. The method according to claim 1,
And the partially re-liquefied evaporated gas and the gaseous evaporated gas passing through the third expansion means are sent together to the storage tank. The method according to claim 1,
Further comprising a gas-liquid separator for separating a part of the re-liquefied evaporated gas from the evaporated gas remaining in the gaseous state while passing through the third expansion means. The method of claim 5,
The gaseous vaporized gas separated by the gas-liquid separator is sent to the front end of the heat exchanger,
And the re-liquefied evaporated gas separated by the gas-liquid separator is sent to the storage tank. The method of claim 5,
Wherein the gaseous state evaporated gas separated by the gas-liquid separator and the re-liquefied evaporated gas are sent together to the storage tank. The method of claim 5,
Wherein the gaseous vaporized gas separated by the gas-liquid separator and the re-liquefied vaporized gas are separated and sent separately to the storage tank. The method of claim 8,
Wherein the gaseous evaporated gas separated by the gas-liquid separator is sent to a lower portion of the storage tank filled with liquefied natural gas. The method according to any one of claims 1 to 9,
Wherein the storage tank stores liquefied gas containing ethane or ethylene as a main component. The method according to any one of claims 1 to 9,
Further comprising a plurality of coolers installed downstream of the plurality of compressors to lower the temperature of the evaporative gas. The method according to any one of claims 1 to 9,
Wherein the first expansion means, the second expansion means, and the third expansion means are expansion valves or inflators. A method for re-liquefaction using evaporative gas as a cooling fluid for re-liquefying evaporated gas generated in a liquefied gas storage tank,
The evaporation gas is discharged from the storage tank,
The evaporation gas discharged from the storage tank is compressed in multiple stages,
The compressed evaporated gas and the evaporated gas discharged from the storage tank are heat-exchanged,
A part of the evaporated gas that has passed through the heat exchanger is expanded by the first expansion means and sent to the first intermediate cooler,
The other part of the evaporated gas passing through the heat exchanger is heat-exchanged with the evaporated gas expanded by the first expansion means in the first intermediate cooler,
A portion of the evaporated gas that has passed through the first intercooler is expanded by the second expansion means and sent to the second intercooler,
Another portion of the evaporated gas that has passed through the first intercooler is heat-exchanged with the evaporated gas expanded by the second expansion means in the second intermediate cooler,
Wherein the evaporating gas that has passed through the second intercooler is expanded by the third expansion means to partially re-liquefy. 14. The method of claim 13,
Wherein the evaporation gas passing through the first expansion means and the evaporation gas passing through the second expansion means are combined with evaporation gas of similar pressure during the process of multi- Gas reclamation method. 14. The method of claim 13,
And the evaporated gas expanded by the third expansion means is sent to the storage tank in a vapor-liquid mixed state. 14. The method of claim 13,
The evaporated gas re-liquefied among the evaporated gases expanded by the third expansion means is sent to the storage tank,
Wherein the evaporation gas remaining in the gaseous state in the evaporation gas expanded by the third expansion means is heat-exchanged with the compressed evaporation gas together with the evaporation gas discharged from the storage tank. 14. The method of claim 13,
The evaporated gas re-liquefied among the evaporated gases expanded by the third expansion means is sent to the storage tank,
Wherein the evaporation gas remaining in the gaseous state in the evaporation gas expanded by the third expansion means is sent to the lower portion of the storage tank where the liquefied natural gas is filled.

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