KR20120111112A - Vessel - Google Patents

Abstract

PURPOSE: A ship is provided to save energy by preventing liquefied natural gas used to the fuel of a high pressure jetting engine from being unnecessarily overcooled. CONSTITUTION: A ship comprises a storage tank(110), an evaporative gas compression part(130), a condenser(140), a gas-liquid separator(170), a fuel supply line, a pump(180), and a vaporizer(190). The storage tank stores liquefied natural gas. The evaporative gas compression part compresses evaporative gas supplied from the storage tank. The condenser overcools the evaporative gas compressed in the evaporative gas compression part after the evaporative gas is reliquefied by heat-exchanging with refrigerant. The gas-liquid separator separates liquefied natural gas from the saturated liquefied natural gas supplied from the condenser. The fuel supply line supplies the liquefied natural gas separated from the gas-liquid separator to a high pressure gas jetting engine. The pump compresses the separated liquefied natural gas. The vaporizer vaporizes the liquefied natural gas compressed in the pump. [Reference numerals] (200) High pressure jetting engine

Description

Vessel {Vessel}

The present invention relates to a ship.

Liquefied Natural Gas (LNG) is obtained by liquefying natural gas (methane) based on methane (hereinafter referred to as "NG") by cooling it to about -162 ℃. Colorless, transparent liquid with a volume of about 1/600 compared to NG. Therefore, when liquefied and transported to LNG during the transfer of NG can be very efficiently transported, for example, an LNG carrier that can transport (transport) LNG to the sea is used.

During the transport of LNG, since the storage tank in which the LNG is stored receives heat continuously from the outside, the LNG in the storage tank becomes hot and can be vaporized accordingly. This is called a boil-off gas (hereinafter referred to as "BOG").

BOG is a type of LNG loss and is an important issue in the transportation of LNG. In addition, there is a risk that the storage tank is damaged if the BOG accumulates in the storage tank and the pressure in the storage tank is increased. Therefore, various methods for treating the BOG have been studied, a method of reliquefying the BOG to return to the storage tank, a method of using the BOG as an energy source of the engine of the ship, and the like.

Recently, LNG carriers have been using a high-pressure gas injection engine that uses LNG stored in a storage tank at high pressure and then vaporized NG as fuel. In detail, the BOG generated in the storage tank may be condensed into LNG in the reliquefaction apparatus, a portion of the condensed LNG may be supplied to the fuel of the high pressure gas injection engine, and the rest may be returned to the storage tank. At this time, the reliquefaction apparatus supercools the LNG in order to minimize the generation of flash gas when the LNG returns to the storage tank.

However, the above prior art has the following problems.

LNG, used as fuel for high-pressure gas injection engines, is compressed to high pressure and then vaporized. Therefore, LNG used as fuel of the high pressure gas injection engine does not need to be supercooled. In other words, the reliquefaction apparatus unnecessarily supercools the LNG to be used as the fuel of the high-pressure gas injection engine, thus wasting energy.

In addition, in order to achieve the best performance of the high-pressure gas injection engine, since the composition ratio of the gas contained in the fuel must be precisely adjusted, an apparatus for removing nitrogen and the like contained in natural gas is required separately. By the way, since the apparatus for removing nitrogen is very expensive, there is a problem that it becomes a factor of the rise of the price.

Embodiments of the present invention seek to provide a vessel that can save energy.

It also aims to provide a low cost vessel.

According to an aspect of the invention, the storage tank for storing the liquefied natural gas; An evaporative gas compression unit configured to compress the evaporated gas supplied from the storage tank; A condenser for supercooling after re-liquefying the boil-off gas compressed by the boil-off gas compression unit with a refrigerant; A gas-liquid separator separating the liquefied natural gas from the liquefied natural gas supplied from the condenser; A fuel supply line for supplying liquefied natural gas separated by the gas-liquid separator to a high pressure gas injection engine; A pump provided to the fuel supply line and compressing the separated liquefied natural gas; And it can provide a vessel comprising a vaporizer for vaporizing the liquefied natural gas compressed in the pump.

In addition, the ship can be characterized in that it further comprises a heat exchanger for heating the boil-off gas supplied to the boil-off gas compression unit.

In addition, the boil-off gas heating source of the heat exchanger may provide a vessel characterized in that the boil-off gas compressed in the boil-off gas compression unit or the refrigerant supplied to the condenser.

In addition, the natural gas separated from the gas-liquid separator may be supplied back to the condenser to provide a vessel, characterized in that recovered to the storage tank after reliquefaction.

In addition, the condenser may provide a vessel characterized in that the refrigerant compression unit for compressing the refrigerant and the expander for expanding the refrigerant to lower the temperature of the refrigerant is connected.

In addition, a preheater for heating the liquefied natural gas may be further provided at the front end of the vaporizer, and the preheater may provide a ship comprising a refrigerant passing through the refrigerant compression unit as a heating source.

In the fuel supply line, the bypass line is branched so that the liquefied natural gas separated from the gas-liquid separator can be recovered to the storage tank, and the liquefied natural gas branched by the bypass line is reliquefied in the condenser. It is possible to provide a vessel characterized in that it is combined with the liquefied natural gas recovered by the storage tank.

According to the ship according to the embodiment of the present invention, the liquefied natural gas to be used as the fuel of the high-pressure gas injection engine does not unnecessarily supercool, it is possible to save energy.

In addition, since it is not necessary to mount an expensive nitrogen removal device for removing nitrogen, the cost can be lowered.

1 is a view schematically showing the structure of a ship according to a first embodiment of the present invention.
2 is a view schematically showing the structure of a ship according to a second embodiment of the present invention.

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

In the following description of the present invention, detailed description of known functions and configurations incorporated herein will be omitted when it may make the subject matter of the present invention rather unclear.

1 is a view schematically showing the structure of a ship according to a first embodiment of the present invention.

Referring to FIG. 1, the vessel 100 according to the first embodiment of the present invention includes a storage tank 110 in which liquefied natural gas (Liquefied Natural Gas, hereinafter referred to as "LNG") is stored, and the storage tank 110. Evaporation gas compression unit 130 for compressing the boiled-off gas (Boiled-Off Gas, hereinafter referred to as "BOG"), heat exchanger disposed in front of the boil-off gas compression unit 130 to cool the compressed BOG 120, a condenser 140 for exchanging BOG with a refrigerant to reliquefy into LNG, a refrigerant compressor 150 for compressing a refrigerant supplied to the condenser 140, an expander 160 for expanding a refrigerant to lower a temperature, Gas-liquid separator 170 for separating LNG from the saturated liquid liquefied LNG from the condenser 140, pump 180 for pressurizing the LNG separated in the gas-liquid separator 170 to high pressure, LNG of high pressure Vaporizer 190 to vaporize with natural gas (hereinafter referred to as "NG"), the high-pressure NG from the vaporizer 190 It may include a high-pressure gas injection engine 200 to generate a propulsion force for propelling the vessel 100 is supplied.

The storage tank 110, the heat exchanger 120, the boil-off gas compression unit 130, the condenser 140, and the gas-liquid separator 170 may be connected by a reliquefaction line 101. In addition, the pump 180 and the vaporizer 190 may be connected by a fuel supply line 102 extending from the gas-liquid separator 170 to the high pressure gas injection engine 200. In addition, the condenser 140, the refrigerant compression unit 150, and the expander 160 may be connected to the refrigerant line 103.

The vessel 100 includes a liquefied natural gas carrier (LNGC), a liquefied natural gas regasification vessel (LNG RV), an liquefied natural gas floating storage and regasification unit (LFSF), and a liquefied natural gas floating, LNG FPSO (production, storage and off) -loading), and may be any vessel capable of operating the sea by storing LNG. In this embodiment, the vessel 100 will be described taking as an example LNGC.

The storage tank 110 is installed on the hull (not shown) of the vessel 100, and is formed to have a heat insulating performance of a predetermined level or more so that LNG can maintain a liquid state. However, since the heat transmitted from the outside cannot be completely blocked, BOG is generated in the storage tank 110.

BOG generated in the storage tank 110 is moved along the reliquefaction line 101 and heated in the heat exchanger 120 and then compressed in the boil-off gas compression unit 130, in the condenser 140 Reliquefy with LNG. A portion of the LNG liquefied in the condenser 140 may be separated from the gas-liquid separator 170 and supplied as a fuel of the high pressure gas injection engine 200, and the remaining portion may be recovered to the storage tank 110. .

In detail, the heat exchanger 120 heat-compresses the BOG supplied from the storage tank 110 and the BOG compressed in the boil-off gas compression unit 130 to increase in temperature, thereby compressing in the boil-off gas compression unit 130. BOG can be cooled before it is supplied to the condenser 140. That is, the BOG supplied from the storage tank 110 in the heat exchanger 120 increases in temperature, and the BOG compressed in the boil-off gas compression unit 130 increases in temperature.

The boil-off gas compressor 130 may include a plurality of compressors 131 to compress BOG preheated by the heat exchanger 120 in multiple stages, and to reduce the load of the condenser 140. A cooler 133 for cooling the BOG may be disposed at the rear end of the compressor 131. The cooler 133 may be a heat exchanger using seawater or fresh water as a cold heat source.

The BOG cooled in the heat exchanger 120 is supplied to the condenser 140 along the reliquefaction line 101 and reliquefied into LNG in the condenser 140.

The condenser 140 is configured to re-liquefy BOG to LNG by heat-exchanging BOG with the refrigerant, is connected to the refrigerant compression unit 150 and the expander 160, and configured to pass through the refrigerant line 103. do.

In detail, the condenser 140 may include a first zone 141 through which BOG passes and re-liquefy, a second zone 142 through which a refrigerant for cooling the BOG of the first zone 141 flows, and the refrigerant compression unit ( The refrigerant compressed in 150 may include a third zone 143 that passes through the refrigerant to be cooled before being introduced into the expander 160. The first, second, and third zones 141, 142, and 143 may be physically independent spaces, and are configured to allow heat exchange between the zones.

An inert gas such as nitrogen may be used as the refrigerant for reliquefaction of the BOG, and in this embodiment, nitrogen is used as the refrigerant.

The refrigerant flows along the refrigerant line 103 and is compressed by the refrigerant compression unit 150. The refrigerant compression unit 150 may include a plurality of compressors 151 to compress the refrigerant in multiple stages. In order to prevent the temperature of the refrigerant from being increased by the compression, the refrigerant compression unit 150 cools the refrigerant. The cooler 153 may be disposed.

The refrigerant passing through the refrigerant compression unit 150 may flow into the third zone 143 along the refrigerant line 103. The refrigerant may be cooled to a temperature suitable for operation of the expander 160 by the refrigerant passing through the third zone 143 and passing through the second zone 142.

The coolant line 103 extends from the third zone 143 to the expander 160, and the coolant passes through the expander 160 and may be cryogenic enough to re-liquefy BOG.

The refrigerant discharged from the expander 160 flows into the second zone 142 along the refrigerant line 103 and passes through the condenser 140. The refrigerant passing through the second zone 142 takes heat away from the BOG passing through the recondensation line 101 to reliquefy the BOG into LNG and takes heat away from the refrigerant passing through the third zone 143. It is possible to lower the temperature of the refrigerant.

The refrigerant discharged from the second zone 142 may be circulated through the refrigerant line 103 by flowing back into the refrigerant compression unit 150 along the refrigerant line 103.

The BOG flowing into the first zone 141 of the condenser 140 through the reliquefaction line 101 passes through the first zone 141 and is re-liquefied into saturated LNG. In this case, at a point where a saturated LNG is formed, the reliquefaction line 101 may exit the first zone 141 and be connected to the gas-liquid separator 170. For example, the reliquefaction line 101 may be configured to exit to the outside of the first zone 141 at the point where the dryness of the LNG drops to 0.8 and be connected to the gas-liquid separator 170.

The gas-liquid separator 170 separates the saturated LNG into LNG and NG.

The NG separated by the gas-liquid separator 170 may be introduced into the first zone 141 again along the reliquefaction line 101 to be liquefied and then recovered into the storage tank 110. In this case, the NG flowing back into the first zone 141 may be recooled after being liquefied. For this purpose, the reliquefaction line 101 may include a refrigerant immediately after flowing into the NG and the second zone 142. It may be configured to allow heat exchange.

The LNG separated from the gas-liquid separator 170 is provided to the high pressure gas injection engine 200 along the fuel supply line 102. That is, LNG of a saturation temperature that is not supercooled may be supplied to the high pressure gas injection engine 200.

In the fuel supply line 102, the pump 180 for compressing LNG at high pressure and the vaporizer 190 for vaporizing the compressed LNG with NG and supplying the compressed gas to the high pressure gas injection engine 200 may be sequentially disposed. Can be.

The high pressure gas injection engine 200 may generate a driving force by using the high pressure NG supplied from the vaporizer 190.

The fuel supply line 102 may be provided with an LNG bypass line 102 ′ to return a portion of the LNG separated from the gas-liquid separator 170 to the storage tank 110. The LNG bypass line 102 ′ is branched from the fuel supply line 102 connecting the gas-liquid separator 170 and the pump 180 to extend from the condenser 140 to the storage tank 110. May be connected to the reliquefaction line 101. That is, the LNG branched into the LNG bypass line 102 ′ may be recovered by combining the LNG liquefied in the condenser 140 and the LNG supplied to the storage tank 110. The LNG bypass line 102 ′ may be provided with a valve for adjusting the flow rate of the LNG.

In addition, the vessel 100 may further include a preheater 210 installed in the fuel supply line 102. The preheater 210 may be disposed between the pump 180 and the vaporizer 190, and is preheated before supplying the LNG compressed by the pump 180 to the vaporizer 190.

The refrigerant passing through the refrigerant compression unit 150 may be used as a heat source of the preheater 210. For this purpose, a first refrigerant branch line 103 ′ may be connected to the refrigerant passage 103. The first refrigerant branch line 103 ′ extends from any point between the refrigerant compression unit 150 and the third zone 143 and passes through the preheater 210 to the third zone 143. And at any point between the inflator 160.

According to the ship 100 according to the first embodiment of the present invention having the configuration as described above, the BOG generated in the storage tank 110 passes through the condenser 140 along the reliquefaction line 101 Re-liquefied with LNG, it can be recovered to the storage tank 110 after being subcooled.

At this time, the saturated LNG before the subcooled in the condenser 140 is supplied to the gas-liquid separator 170, the LNG is separated from the gas-liquid separator 170 and supplied to the fuel supply line 102, the pump Passed through the 180 and the vaporizer 190 is provided to the high-pressure gas injection engine 200.

That is, by extracting the LNG from the condenser 140 before the supercooled state at a lower temperature, the amount of heat to be injected into the vaporizer 190 can be reduced, thereby reducing energy consumption of the vaporizer 190. have. Therefore, the energy consumption of the vessel 100 can be saved.

In addition, since the LNG separated from the gas-liquid separator 170 is vaporized, the NG supplied to the high pressure gas injection engine 200 has a smaller nitrogen content than the BOG generated in the storage tank 110. Therefore, even if the nitrogen remover is not separately installed, it is possible to provide a fuel gas having a low nitrogen content required by the high pressure gas injection engine 200. That is, the manufacturing cost of the vessel 100 can be lowered.

In addition, by arranging the preheater 210 in front of the vaporizer 190, it is possible to reduce the amount of heat to be supplied to the vaporizer 190, it is possible to reduce the energy consumption of the vessel (100).

Hereinafter, a ship according to a second embodiment of the present invention will be described with reference to FIG. 2. However, since the second embodiment has a difference in configuration related to the heat exchanger compared to the first embodiment, the description will be mainly focused on the differences, and the same reference numerals and descriptions of the first embodiment will be used.

2 is a view schematically showing the structure of a ship according to a second embodiment of the present invention.

2, the reliquefaction line 101 'of the vessel 100' according to the second embodiment of the present invention is the BOG passing through the boil-off gas compression unit 130 is the Configured to enter the first zone 141.

In addition, the second refrigerant branch line 103 "extends from the refrigerant line 103 to be connected to the heat exchanger 120 '. In detail, the BOG flowing into the heat exchanger 120' is the second refrigerant branch. Heat exchanged with the refrigerant flowing through the line 103 ″ and preheated before being supplied to the boil-off gas compression unit 130, and the refrigerant flowing through the refrigerant line 103 is deprived of heat from the heat exchanger 120 ′ to BOG. Can be cooled.

The second refrigerant branch line 103 ″ extends from the rear end of the refrigerant compression unit 150 to pass through the heat exchanger 120 ′ and then passes through the third zone 143. Can be configured to join.

As a result, since the flow rate of the refrigerant flowing in a portion of the third zone 143 may be reduced, it is possible to reduce the cooling heat loss of the refrigerant flowing in the second zone 142.

While the present invention has been described in connection with certain embodiments thereof, it will be understood by those of ordinary skill in the art that various changes in form and details may be made therein without departing from the spirit and scope of the invention as defined by the appended claims. Skilled artisans may implement a pattern of features that are not described in a combinatorial and / or permutational manner with the disclosed embodiments, but this is not to depart from the scope of the present invention. It will be apparent to those skilled in the art that various changes and modifications may be readily made without departing from the spirit and scope of the invention as defined by the appended claims.

100, 100 ': Vessel 110: storage tank
120: heat exchanger 130: evaporation gas compression unit
140: condenser 150: refrigerant compression unit
160: expander 170: gas-liquid separator
180: pump 190: carburetor
200: high pressure gas injection engine 101: reliquefaction line
102: fuel supply line 102 ': LNG bypass line
103: refrigerant line 103 ′: first refrigerant branch line
103 ": second refrigerant branch line 210: preheater

Claims (7)

A storage tank for storing liquefied natural gas;
An evaporative gas compression unit configured to compress the evaporated gas supplied from the storage tank;
A condenser for supercooling after re-liquefying the boil-off gas compressed by the boil-off gas compression unit with a refrigerant;
A gas-liquid separator separating the liquefied natural gas from the liquefied natural gas supplied from the condenser;
A fuel supply line for supplying liquefied natural gas separated by the gas-liquid separator to a high pressure gas injection engine;
A pump provided to the fuel supply line and compressing the separated liquefied natural gas; And
Ship comprising a vaporizer for vaporizing the liquefied natural gas compressed in the pump. The method of claim 1,
And a heat exchanger for heating the boil-off gas supplied to the boil-off gas compression unit. The method of claim 2,
The boil-off gas heating source of the heat exchanger is a vessel characterized in that the boil-off gas compressed by the boil-off gas compression unit or the refrigerant supplied to the condenser. The method of claim 1,
The natural gas separated in the gas-liquid separator is supplied back to the condenser to be liquefied and recovered to the storage tank. The method of claim 1,
In the condenser,
A refrigerant compression unit compressing the refrigerant,
A ship characterized in that the expander for expanding the refrigerant to lower the temperature of the refrigerant is connected. The method of claim 5, wherein
The preheater for heating the liquefied natural gas is further provided at the front end of the vaporizer,
The preheater is a vessel, characterized in that to use the refrigerant passing through the refrigerant compression unit as a heating source. The method of claim 4, wherein
The bypass line is branched from the fuel supply line so that the liquefied natural gas separated from the gas-liquid separator can be recovered to the storage tank.
The natural gas branched by the bypass line is combined with the liquefied natural gas re-liquefied in the condenser and recovered to the storage tank.

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