KR20110046945A - Fuel gas supplying system for supplying fuel gas to a liquified fuel gas propulsion ship with a high-pressure gas injection engine and a low-pressure gas injection engine - Google Patents

Abstract

PURPOSE: A system for supplying fuel gas to a liquefied fuel gas propulsion ship with a high-pressure gas injection engine and a low-pressure gas injection engine is provided to simultaneously supply fuel from a fuel gas supply line to a high-pressure gas injection engine and a low-pressure gas injection engine. CONSTITUTION: A system for supplying fuel gas to a liquefied fuel gas propulsion ship with a high-pressure gas injection engine and a low-pressure gas injection engine comprises a liquefied fuel gas tank(10), a fuel gas supply line(L2), a high-pressure pump(50), a vaporizer(60), a branch pipe(71), and a decompression unit(70). The liquefied fuel gas tank stores liquefied fuel gas. The fuel gas supply line is connected from the liquefied fuel gas tank to a high-pressure injection engine. The high-pressure pump is installed in the fuel gas supply line and compresses liquefied fuel gas. The vaporizer is installed in the fuel gas supply line and vaporizes the compressed liquefied fuel gas. The branch pipe is branched from the fuel gas supply line and supplies the vaporized fuel gas to the low-pressure injection engine. The decompression unit is installed in the branch pipe and compresses the vaporized fuel gas.

Description

Fuel gas supplying system for supplying fuel gas to a liquified fuel gas propulsion ship with a high-pressure gas injection engine and a low pressure gas injection engine

The present invention relates to a system for supplying fuel gas to a liquefied fuel gas propulsion vessel having a high pressure gas injection engine and a low pressure gas injection engine. More specifically, a portion of the fuel gas supplied to the high pressure gas injection engine is branched to the low pressure gas injection engine to supply fuel gas to the liquefied fuel gas propulsion vessel that simultaneously supplies fuel to the high pressure gas injection engine and the low pressure gas injection engine. It is about the system.

Recently, interest in propulsion engines using liquefied fuel gas, for example, LNG (or LPG, DME), which is much cheaper than heavy oil and is a clean energy source due to rising oil prices, has increased.

Marine engines that use liquefied fuel gas as fuel to obtain propulsion power include high-pressure gas injection engines such as ME-GI (Gas Injection engine from Man B & W).

As an example, an LNG carrier using LNG (Liquified Natural Gas) among the liquefied fuel gas will be described as an LNG tank for storing LNG. Since the liquefaction temperature of natural gas is a cryogenic temperature of -163 ° C at atmospheric pressure, LNG is evaporated even if the temperature is only slightly higher than -163 ° C. Although LNG tanks of LNG carriers are insulated, the external heat is continuously transferred to LNG. During transport of LNG by LNG carriers, LNG is continuously vaporized in the LNG tanks to produce boil-off gas. Off Gas; BOG) occurs.

When the boil-off gas accumulates in the LNG tank, the pressure in the LNG tank is excessively increased, so in some cases, the boil-off gas is used as the fuel of the main propulsion device to treat the boil-off gas generated in the LNG tank. If the amount of boil-off gas exceeds that used as fuel in the main propulsion unit, this excess is discharged into the air or sent to a gas combustor for incineration.

In order to use the boil-off gas generated in the LNG tank as the fuel of the main propulsion device, the boil-off gas is compressed to high pressure by a multistage compressor and supplied to the main propulsion device. However, due to such multi-stage compression, the fuel gas supply system is very complicated and there is a problem in that excessive power is required to compress the boil-off gas, which is a gas, at high pressure.

Therefore, the boil-off gas generated in the LNG tank is liquefied by the boil-off gas reliquefaction apparatus and returned to the LNG tank again, and the LNG propulsion fuel of the LNG carrier ship vaporizes the LNG stored in the LNG tank as the ship propulsion fuel of the LNG carrier. Gas supply systems are being used.

1 is a view showing a schematic configuration of a fuel gas supply system of a conventional LNG carrier.

In such a system, the boil-off gas discharged from the LNG tank 1 is compressed in the compressor 2 through the boil-off gas discharge line L1 and then re-liquefied while passing through a Reliquefaction Unit 3. The reliquefied boil-off gas is sent back to the LNG tank (1).

The propulsion of the LNG carrier is carried out by extracting the LNG stored in the LNG tank 1, compressing it to a high pressure in the high pressure pump 5, and then vaporizing it in the vaporizer 6 to burn it in the high pressure gas injection engine. In such a system, a portion of the boil-off gas compressed by the compressor 2 is sent to a recondenser 4 to be condensed with cold LNG to reduce the cooling load for re-liquefying the boil-off gas.

On the other hand, LNG carriers are equipped with a low-pressure gas injection engine such as a dual fuel diesel electric propulsion system (DFDE) engine or a gas turbine, and may be used as an engine for generating electricity in a ship or in an emergency propulsion engine.

Conventionally, when a high pressure gas injection engine used for propulsion and a low pressure gas injection engine used for power generation are provided on a ship such as an LNG carrier, each fuel gas supply line, a pump, and a vaporizer are installed separately. . This complicates the construction of the fuel gas supply system of liquefied fuel gas propulsion vessels such as LNG carriers, thus increasing the cost and installation space for the device.

Accordingly, the present invention has been made in view of the above circumstances, and it is possible to simplify the fuel gas supply system of a liquefied fuel gas propulsion ship having a high pressure gas injection engine and a low pressure gas injection engine, thereby reducing the cost and installation space for the device. The aim is to provide a fuel gas supply system for a liquefied fuel gas propulsion vessel.

A system for supplying fuel gas to a liquefied fuel gas propulsion vessel having a high pressure gas injection engine and a low pressure gas injection engine using liquefied fuel gas as a fuel includes: a liquefied fuel gas tank for storing liquefied fuel gas; A fuel gas supply line connected from the liquefied fuel gas tank to the high pressure gas injection engine; A high pressure pump installed in the fuel gas supply line to compress the liquefied fuel gas; A vaporizer installed in the fuel gas supply line to vaporize the liquefied fuel gas compressed by the high pressure pump and to supply the high pressure gas injection engine; A branch pipe branched from the fuel gas supply line at the rear end of the vaporizer to supply the vaporized liquefied fuel gas to the low pressure gas injection engine; Decompression means for reducing the vaporized liquefied fuel gas provided in the middle of the branch pipe; Characterized in that it comprises a.

In addition, a heater installed at the rear end of the decompression means for heating the vaporized liquefied fuel gas; It characterized in that it further comprises.

In addition, a compressor for compressing the boil-off gas generated in the liquefied fuel gas tank; A recondenser disposed in front of the high pressure pump in the fuel gas supply line; Including, and the boil-off gas compressed by the compressor is mixed with the liquefied fuel gas extracted from the liquefied fuel gas tank in the recondenser.

In addition, a compressor for compressing the boil-off gas generated in the liquefied fuel gas tank; A reliquefaction apparatus for reliquefying the boil-off gas compressed by the compressor; It characterized in that it further comprises.

In addition, a recondenser disposed in front of the high pressure pump in the fuel gas supply line; And a portion of the boil-off gas compressed by the compressor is mixed with the liquefied fuel gas extracted from the liquefied fuel gas tank in the recondenser.

In addition, the liquefied boil-off gas in the reliquefaction apparatus is characterized in that returned to the liquefied fuel gas tank.

In addition, the high pressure gas injection engine is a propulsion engine for the propulsion of the ship, the low pressure gas injection engine is characterized in that the power generation engine for power generation.

In addition, the low pressure gas injection engine is characterized in that the DFDE engine or gas turbine.

In addition, the pressure of the fuel gas supplied to the high-pressure gas injection engine is characterized in that 150 to 600 bar.

In addition, the pressure of the fuel gas supplied to the low pressure gas injection engine is characterized in that 5 to 30 bar.

The system for supplying fuel gas to a liquefied fuel gas propulsion vessel having a high pressure gas injection engine and a low pressure gas injection engine using liquefied fuel gas as a fuel is removed from the liquefied fuel gas tank as the high pressure gas injection engine. After the liquefied liquefied fuel gas is compressed to high pressure, it is vaporized and supplied as fuel gas, and the low pressure gas injection engine branches and vaporizes the liquefied liquefied fuel gas to be supplied to the high pressure gas injection engine, and then depressurizes it as fuel gas. It is characterized in that the supply.

In addition, the boil-off gas generated in the liquefied fuel gas tank is characterized in that the reliquefaction in the reliquefaction apparatus.

In addition, after the part of the boil-off gas generated in the liquefied fuel gas tank is compressed, it is characterized in that mixed with the liquefied fuel gas taken out of the liquefied fuel gas tank and condensed.

According to the present invention, a portion of the fuel gas supplied to the high pressure gas injection engine is branched and decompressed and then supplied to the low pressure gas injection engine to simultaneously supply fuel to the high pressure gas injection engine and the low pressure gas injection engine from one fuel gas supply line. By supplying, the configuration of the fuel gas supply system for each engine can be simplified, thereby reducing the cost and installation space for the device.

Hereinafter, the configuration and operation of the preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings. Here, in adding reference numerals to the components of each drawing, it should be noted that the same components are denoted by the same reference numerals as much as possible even if they are shown in different drawings.

2 is a view showing a schematic configuration of a system for supplying fuel gas to a liquefied fuel gas propulsion ship according to the present invention.

The liquefied fuel gas propulsion vessel of the present invention is configured to obtain the propulsion power of the vessel by using the liquefied fuel gas as fuel. The liquefied fuel gas propulsion ship is provided with a high pressure gas injection engine and a low pressure gas injection engine.

The high-pressure gas injection engine is mainly an engine used for propulsion of a ship, for example, there is a ME-GI engine (Gas Injection engine of Man B & W). The pressure of the fuel gas supplied to the high pressure gas injection engine is about 150 to 600 bar (gauge pressure).

The low pressure gas injection engine is mainly used for power generation, and in an emergency, the engine is also used for propulsion of a ship, for example, a DFDE (Dual Fuel Diesel Electric) engine or a gas turbine. The pressure of the fuel gas supplied to the low pressure gas injection engine is about 5 to 30 bar.

In the above, liquefied fuel gas refers to a fuel gas liquefied and stored, such as LNG, LPG, DME.

LNG, or Liquefied Natural Gas, is a liquefied natural gas collected from a gas field, with methane as the main component. When LNG is liquefied by lowering the temperature or applying pressure, the volume is reduced to about 1/600, which is advantageous in terms of space efficiency.However, the boiling point is about 162 degrees below zero. Should be kept as

LPG, or liquefied petroleum gas, has a relatively low pressure (6) for heavy hydrocarbons (two or more carbon atoms) from crude oil or crude oil refinery, or heavy hydrocarbons from natural gas. ~ 7 kg / ㎠) was added to cool and liquefy. When liquefied, the volume is reduced to approximately 1/250, which is convenient for storage and transportation. The main components are propane and butane, and may contain small amounts of ethane, propylene, butylene, and the like.

DME, that is, dimethyl ether, is a kind of ether, which is less flammable and nontoxic than LPG, and has high oxygen content, so it is characterized by low environmental load due to less smoke.

Hereinafter, referring to FIG. 2, a system for supplying fuel gas to an LNG propulsion ship using LNG as liquefied fuel gas will be described as an example.

In the fuel gas supply system, a line is connected from the upper portion of the LNG tank 1 to the lower portion of the LNG tank 1 through the compressor 20 and the reliquefaction device 30 to re-liquefy the boil-off gas. This is called. The line from which the LNG tank 1 is connected to the high pressure gas injection engine through the recondenser 40, the high pressure pump 50, and the vaporizer 60 from the lower part of the LNG tank 1 is called fuel gas supply line L2. .

Since the liquefaction temperature of LNG is a cryogenic temperature of -163 占 폚 at atmospheric pressure, LNG is evaporated even if the temperature is only slightly higher than -163 占 폚. Since the external heat is transferred to the LNG tank 10, LNG is vaporized in the LNG tank to continuously generate boiled gas (BOG).

When the boil-off gas is accumulated in the LNG tank 10, the pressure in the LNG tank is excessively increased, so to prevent this, the boil-off gas generated in the LNG tank 10 is compressed along the boil-off gas liquefaction line L1. And then liquefied in the reliquefaction apparatus 30. In the reliquefaction apparatus 30, for example, the evaporation gas is cooled and liquefied by a refrigeration cycle using nitrogen (N ₂ ) as a refrigerant. The reliquefied boil-off gas is preferably returned to the LNG tank 10.

In order to reduce the cooling load for liquefying the boil-off gas in the reliquefaction device 30, a portion of the boil-off gas compressed by the compressor 20 is sent to the re-condenser 40. In the recondenser 40, the boil-off gas is mixed with LNG extracted from the LNG tank 10 to condense. Since a relatively small amount of evaporated gas is sent to the recondenser 40 as compared to LNG, the evaporated gas may be mixed with cold LNG and condensed.

When the LNG propulsion vessel is an LNG carrier for transporting LNG, it is preferable that the amount of boil-off gas generated in the LNG tank is large so as to re-liquefy through the reliquefaction apparatus 30. However, in the case of a general LNG propulsion vessel that stores LNG as a fuel only, the amount of boil-off gas generated in the LNG tank 10 is all processed in the recondenser 40 because it stores a relatively small amount of LNG compared to the LNG carrier. It can be as small as possible. In this case, the present invention does not include the reliquefaction apparatus 30, and may be configured such that all of the boil-off gas generated in the LNG tank 10 is sent to the recondenser 40.

Next, the LNG passing through the recondenser 40 is sent to the high pressure pump 50 and compressed at high pressure. For example, it is compressed to about 250 bar.

The LNG compressed by the high pressure pump 50 is sent to the vaporizer 60 is vaporized. The vaporized LNG is sent to the high pressure gas injection engine and used as fuel gas.

In the present invention, the fuel gas supply line for the fuel gas used in the low-pressure gas injection engine is not configured separately from the high-pressure gas injection engine, and branched and depressurized part of the fuel gas supplied to the high-pressure gas injection engine to reduce the low pressure gas injection. Supply it to the engine and use it.

More specifically, part of the LNG vaporized in the vaporizer 60 is branched through the branch pipe (71). The branch pipe 71 is for supplying the vaporized LNG branched from the fuel gas supply line L2 at the rear end of the vaporizer 60 to the low pressure gas injection engine.

The vaporized LNG branched through the branch pipe 71 is decompressed to a pressure enough to be supplied to the low pressure gas injection engine while passing through the decompression means, for example, the decompression valve 70. LNG vaporized while passing through the pressure reducing valve 70 is decompressed, for example, from about 250 bar to about 8 bar. The reduced vaporized LNG is supplied to the low pressure gas injection engine and used as fuel gas.

On the other hand, if the vaporized LNG is reduced to about 250 bar to 8 bar, the temperature of the gas is lowered may not meet the temperature conditions of the fuel gas required by the low-pressure gas injection engine. To this end, the pressure reducing valve 70 may be provided with a heater 72 to heat the fuel gas and then supply the fuel gas to the low pressure gas injection engine.

As such, the present invention does not separately constitute a high-pressure gas injection engine used for propulsion in a liquefied fuel gas propulsion vessel and a liquefied fuel gas supply line supplied to a low-pressure gas injection engine used for power generation. A part of the fuel gas supplied to the injection engine is branched and supplied to the low pressure gas injection engine. In this way, a high pressure pump 50 for compressing liquefied fuel gas, a vaporizer 60 for vaporizing liquefied fuel gas, a fuel gas supply line, and the like do not need to be separately configured for each high pressure gas injection engine and low pressure gas injection engine. do. This simplifies the construction of the fuel gas supply system of the high pressure gas injection engine and the low pressure gas injection engine, thereby reducing the cost and installation space for the device.

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 will be.

1 is a view showing a schematic configuration of a fuel gas supply system of a conventional LNG carrier.

2 is a view showing a schematic configuration of a system for supplying fuel gas to a liquefied fuel gas propulsion ship according to the present invention.

<Explanation of symbols for the main parts of the drawings>

10: liquefied fuel gas tank

20: compressor

30: reliquefaction apparatus

40: recondenser

50: high pressure pump

60: carburetor

70: pressure reducing valve

71: branch pipe

L1: Boiler Gas Liquefaction Line

L2: Fuel Gas Supply Line

Claims (13)

In a system for supplying fuel gas to a liquefied fuel gas propulsion ship having a high pressure gas injection engine and a low pressure gas injection engine using liquefied fuel gas as fuel, A liquefied fuel gas tank for storing liquefied fuel gas; A fuel gas supply line connected from the liquefied fuel gas tank to the high pressure gas injection engine; A high pressure pump installed in the fuel gas supply line to compress the liquefied fuel gas; A vaporizer installed in the fuel gas supply line to vaporize the liquefied fuel gas compressed by the high pressure pump and to supply the high pressure gas injection engine; A branch pipe branched from the fuel gas supply line at the rear end of the vaporizer to supply the vaporized liquefied fuel gas to the low pressure gas injection engine; Decompression means for reducing the vaporized liquefied fuel gas provided in the middle of the branch pipe; Fuel gas supply system comprising a. The method according to claim 1, A heater installed at a rear end of the decompression means to heat the vaporized liquefied fuel gas; Fuel gas supply system characterized in that it further comprises. The method according to claim 1, A compressor for compressing the boil-off gas generated in the liquefied fuel gas tank; A recondenser disposed in front of the high pressure pump in the fuel gas supply line; Including, The boil-off gas compressed by the compressor is mixed with the liquefied fuel gas taken out of the liquefied fuel gas tank in the recondenser. The method according to claim 1, A compressor for compressing the boil-off gas generated in the liquefied fuel gas tank; A reliquefaction apparatus for reliquefying the boil-off gas compressed by the compressor; Fuel gas supply system characterized in that it further comprises. The method according to claim 4, A recondenser disposed in front of the high pressure pump in the fuel gas supply line; Including, And a portion of the boil-off gas compressed by the compressor is mixed with the liquefied fuel gas extracted from the liquefied fuel gas tank in the recondenser. The method according to claim 4, And the boil-off gas re-liquefied in the re-liquefaction apparatus is returned to the liquefied fuel gas tank. The method according to any one of claims 1 to 6, The high pressure gas injection engine is a propulsion engine for the propulsion of the ship, the low pressure gas injection engine is a fuel gas supply system, characterized in that the power generation engine for power generation. The method according to any one of claims 1 to 6, The low pressure gas injection engine is a fuel gas supply system, characterized in that the DFDE engine or gas turbine. The method according to any one of claims 1 to 6, The fuel gas supply system, characterized in that the pressure of the fuel gas supplied to the high-pressure gas injection engine is 150 to 600 bar. The method according to any one of claims 1 to 6, The fuel gas supply system, characterized in that the pressure of the fuel gas supplied to the low pressure gas injection engine is 5 to 30 bar. In a system for supplying fuel gas to a liquefied fuel gas propulsion ship having a high pressure gas injection engine and a low pressure gas injection engine using liquefied fuel gas as fuel, As the high pressure gas injection engine, the liquefied fuel gas extracted from the liquefied fuel gas tank is compressed to high pressure, and then vaporized and supplied as fuel gas. The low pressure gas injection engine is a fuel gas supply system, characterized in that the branched and depressurized vaporized liquefied fuel gas to be supplied to the high pressure gas injection engine, and is supplied as a fuel gas. The method of claim 11, And a reliquefaction device for reliquefying the boil-off gas generated in the liquefied fuel gas tank. The method of claim 11, And a portion of the boil-off gas generated in the liquefied fuel gas tank is compressed and mixed with the liquefied fuel gas taken out of the liquefied fuel gas tank to condense.

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