KR20200075199A - Fuel Supply System And Method For Ship - Google Patents

Abstract

Disclosed are a fuel supply system and a fuel supply method for a ship, which can prevent fuel abuse. The fuel supply system for a ship according to the present invention comprises: a first fuel supply line compressing a boil-off gas generated from a liquefied gas stored in a storage tank of the ship to supply the compressed gas to a high pressure engine; a gas discharge line discharging a portion of the boil-off gas which is supplied to the high pressure engine from the first fuel supply line to alleviate overpressure caused by a load change of the high pressure engine; an overpressure control valve provided on the gas discharge line to control discharge of the boil-off gas; and a pressure control valve provided on the gas discharge line to control pressure of the boil-off gas, wherein the pressure control valve sets the pressure of the boil-off gas to a fuel supply pressure of a fuel consuming place in the ship, and the boil-off gas is supplied to the fuel consuming place in the ship through the pressure control valve.

Description

Fuel supply system and method for ships

The present invention relates to a fuel supply system and method of a ship, and more specifically, to compress the boil-off gas generated from liquefied gas stored in the ship's storage tank and supply it to the ship's high-pressure engine, and part of the boil-off gas supplied to the ship's high-pressure engine. To release the pressure from the supply line to relieve the overpressure caused by changes in the load of the high-pressure engine, but to relieve the overpressure from the supply line of the fuel, a pressure control valve is provided on the line through which the evaporation gas is discharged, and the evaporation gas that has passed through the pressure control valve is on board. It relates to a fuel supply system and method for a vessel, characterized in that the fuel supply pressure of the fuel consumer is supplied to the fuel consumer on board.

Natural gas is a fossil fuel that contains methane as a main component and contains a small amount of ethane and propane, and has recently been spotlighted as a low-pollution energy source in various technical fields.

Natural gas is consumed a lot with economical and eco-friendly energy, but it has a large volume and is inefficient in transportation and storage to transport it as a natural gas.

In order to compensate for this, a method of transporting and storing in a liquefied natural gas (LNG) state has been proposed. Liquefied natural gas is a colorless, transparent, cryogenic liquid whose natural gas, mainly composed of methane, is cooled at atmospheric pressure to a cryogenic state of -162°C, reducing its volume to one-sixth, and is known to have superior transportability and storage properties than the gaseous state.

However, since the natural gas liquefaction temperature is extremely low at -162°C under normal pressure, LNG is easily sensitive to temperature changes and evaporates easily. Although the LNG storage tank of the LNG carrier is insulated, since external heat is continuously transferred to the LNG storage tank, LNG is continuously vaporized in the LNG storage tank during the LNG transportation process by the LNG carrier, and LNG Boil-off gas (BOG) is generated in the storage tank.

BOG is a kind of LNG loss, which is an important problem in the transportation efficiency of LNG, and when boil-off gas accumulates in the LNG storage tank, the pressure in the LNG storage tank rises excessively, and there is a risk of tank damage, so the BOG generated in the LNG storage tank A variety of methods for dealing with are being studied.

Recently, for the treatment of BOG, a method of re-liquefying BOG and returning it to a storage tank, a method of using BOG as an energy source of a ship's engine, and the like are used. And for the excess BOG, a method of combustion in a gas combustion unit (GCU) is used.

In addition, a dual fuel engine that can use natural vaporized or forced vaporized gas and fuel oil as fuel in a propulsion unit or a power generation unit in the LNG carrier itself has been developed and used as a main engine and a generator engine. It is also supplied as fuel on board.

1 schematically shows a fuel supply system of a ship equipped with a high-pressure engine and a low-pressure engine receiving liquefied gas as fuel.

As shown in FIG. 1, in a ship equipped with a high-pressure engine and a low-pressure engine receiving liquefied gas as fuel, the compressed gas is compressed by a compressor according to the required pressure of the high-pressure engine and supplied to the high-pressure engine, Compressed gas can be supplied as fuel to a low-pressure engine through a part of the compressor.

However, when the load of the engine changes, the pressure of the gas coming from the compressor may change. For the safety of piping and equipment, piping that can discharge a part of the gas from the supply pipe so that the pressure of the gas does not rise above a certain pressure Prepare to discharge the gas to prevent overpressure.

The discharged gas flows into the storage tank, and since the lubricant is mixed with the gas, returning it to the storage tank may contaminate the liquefied gas.

The present invention solves this problem and proposes a system capable of discharging gas to prevent overpressure and efficiently utilizing the discharged gas.

According to an aspect of the present invention for solving the above problems, a first fuel supply line for compressing the boil-off gas generated from the liquefied gas stored in the storage tank of the ship to supply to the high-pressure engine of the ship;

A gas discharge line that discharges a portion of the boil-off gas supplied to the high-pressure engine from the first fuel supply line to relieve overpressure caused by a load change of the high-pressure engine;

An overpressure control valve provided on the gas discharge line to control the discharge of the evaporated gas; And

Included in the gas discharge line is provided in the pressure control valve for adjusting the pressure of the boil-off gas,

It is provided downstream of the overpressure control valve of the gas discharge line to control the pressure of the evaporation gas; includes,

The pressure control valve sets the pressure of the boil-off gas to the fuel supply pressure of the ship's fuel consumer, and the boil-off gas is supplied to the ship's fuel consumer through the pressure control valve.

Preferably, the gas discharge line further comprises a buffer tank provided upstream of the pressure regulating valve to store the evaporated gas discharged from the first fuel supply line, wherein the fuel consumption unit includes a low-pressure engine of the ship , The evaporated gas may be supplied from the buffer tank to the low pressure engine via the pressure regulating valve.

Preferably, the fuel consumption unit includes a vessel boiler, and the low-pressure engine and the boil-off gas not supplied to the boiler may be combusted in a gas combustion unit (GCU).

Preferably, the multi-stage compressor is provided on the first fuel supply line to compress the evaporation gas, and a plurality of compressors and coolers are alternately arranged; A second fuel supply line branching from the first fuel supply line and supplying the boil-off gas compressed through a part of the multi-stage compressor to the low-pressure engine; And a re-liquefaction line for generating the compressed boil-off gas from the storage tank through heat exchange with uncompressed boil-off gas to be introduced into the multi-stage compressor, and returning it to the storage tank under reduced pressure. .

Preferably, a third fuel supply line for pumping the liquefied gas from the storage tank to supply to the high-pressure engine; A high pressure pump provided on the third fuel supply line to compress the liquefied gas; And a vaporizer provided on the third fuel supply line and heating the liquefied gas compressed by the high pressure pump to supply it to the high pressure engine.

Preferably, a fourth fuel supply line branching from the third fuel supply line downstream of the carburetor and supplying the compressed and vaporized liquefied gas to the low pressure engine; A pressure reducing valve provided on the fourth fuel supply line to decompress the liquefied gas to be supplied to the low pressure engine; And a heater provided on the fourth fuel supply line and heating the liquefied gas decompressed through the pressure reducing valve according to the fuel supply temperature of the low pressure engine, wherein the gas discharge line is disposed at the front end of the heater. It can be connected to the fourth fuel supply line.

According to another aspect of the present invention, the boil-off gas generated from the liquefied gas stored in the ship's storage tank is compressed and supplied to the ship's high-pressure engine,

A part of the boil-off gas supplied to the high-pressure engine is discharged from a supply line to eliminate overpressure caused by a load change of the high-pressure engine,

A pressure control valve for adjusting the pressure of the boil-off gas is provided in the line from which the boil-off gas is discharged from the supply line, the pressure of the pressure control valve is set to the fuel supply pressure of the fuel consumption on board, and discharged from the supply line. A method of supplying fuel to a vessel is provided, characterized in that the boil-off gas is supplied to a fuel consumer on board through the pressure regulating valve.

Preferably, the fuel consumption unit includes a low-pressure engine and a boiler of the ship, and the remaining vaporized gas supplied to the low-pressure engine and boiler can be combusted in the GCU on board.

In the present invention, in order to relieve overpressure from the fuel supply line, a pressure regulating valve is provided in a line through which the evaporation gas is discharged, and the pressure of the pressure regulating valve is adjusted to the fuel supply pressure of the fuel consumption on board, and the pressure of the evaporated gas discharged from the supply line It is supplied to a fuel consumption vessel on board, such as a low-pressure engine, boiler, etc. through a regulating valve for processing.

Through this, the safety of the equipment and piping of the fuel supply system is secured through the overpressure relief, and the discharged gas is supplied to the on-board fuel consumer to prevent contamination of LNG cargo generated when returning to the storage tank and prevent the waste of fuel. have.

1 schematically shows a fuel supply system of a ship equipped with a high-pressure engine and a low-pressure engine receiving liquefied gas as fuel.
2 schematically shows a fuel supply system for a ship according to a first embodiment of the present invention.
3 schematically illustrates a fuel supply system for a ship according to a second embodiment of the present invention.

In order to fully understand the operational advantages of the present invention and the objects achieved by the practice of the present invention, reference should be made to the accompanying drawings and the contents described in the accompanying drawings, which illustrate preferred embodiments of the present invention.

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, when 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 though they are displayed on different drawings.

In the embodiment of the present invention to be described later, the vessel may be an engine that can use liquefied gas as a fuel for propulsion or power generation engines, or may be any type of vessel that uses liquefied gas as fuel. Typically, LNG carriers (LNG Carrier), liquid hydrogen carriers, LNG RV (Regasification Vessel), including self-propelled ships, LNG FPSO (Floating Production Storage Offloading), LNG FSRU Offshore structures that do not have the ability but are floating on the sea may also be included.

In addition, the present embodiment is transported by liquefying liquefied gas at a low temperature and can be applied to all types of liquefied gas that can be used as fuel. The liquefied gas may be, for example, Liquefied Natural Gas (LNG), Liquefied Ethane Gas (LEG), Liquefied Petroleum Gas (LPG), Liquefied Ethylene Gas, Liquefied Propylene Gas, or the like. However, in the embodiment described later, it will be described as an example that LNG, which is a typical liquefied gas, is applied.

FIG. 2 schematically shows a fuel supply system of a ship according to the first embodiment of the present invention, and FIG. 3 schematically shows a fuel supply system of a ship according to the second embodiment.

As shown in Figure 2, the ship's fuel supply system according to the first embodiment of the present invention compresses the boil-off gas generated from the liquefied gas stored in the ship's storage tank (T) to the ship's high-pressure engine (HE) It includes a first fuel supply line (FL1) to supply, and a gas discharge line (PL) that discharges a part of the evaporation gas supplied to the high-pressure engine from the first fuel supply line to relieve the overpressure caused by the load change of the high-pressure engine, The discharge line is provided with an overpressure control valve 200 that controls the discharge of the evaporated gas, and a pressure control valve 220 that regulates the pressure of the evaporated gas downstream of the overpressure control valve.

The pressure of the pressure regulating valve 220 is adjusted to the fuel supply pressure of the onboard fuel consumer, and the boil-off gas discharged for overpressure relief from the first fuel supply line is supplied to the onboard fuel consumer through a pressure regulating valve.

In the gas discharge line PL, a buffer tank 210 for storing the evaporated gas discharged from the first fuel supply line is provided upstream of the pressure regulating valve 220. The fuel consumption unit may be a low-pressure engine (LE) of the ship, and the evaporated gas discharged through the gas discharge line (PL) to relieve overpressure is supplied to the buffer tank 210 and stored, if necessary, a pressure regulating valve ( The pressure may be reduced through 220) and supplied to the low pressure engine LE.

The high pressure engine HE and the low pressure engine LE may be engines for propulsion or power generation of ships.

The high-pressure engine may be, for example, a 2-stroke, ME-GI engine employing a diesel cycle that directly injects high-pressure natural gas of 300 to 350 bar into the combustion chamber near the top dead center of the piston. The low-pressure engine is an engine that receives fuel at a lower pressure than a high-pressure engine, and is composed of, for example, a four-stroke engine, and injects natural gas at a level of about 5 to 10 bar, which is relatively low pressure, into the combustion air inlet, thereby compressing as the piston rises. It may be a DFDE or dual fuel diesel generator (DFDG) adopting an Otto Cycle.

The first fuel supply line FL1 is provided with a compressor for compressing the boil-off gas to the fuel supply pressure of the high-pressure engine. A plurality of compressors and coolers, for example, a multi-stage compressor 100 in which each of the five compressors and coolers are alternately arranged ).

The second fuel supply line FL2 is branched from the first fuel supply line to supply compressed boil-off gas to the low-pressure engine. The second fuel supply line FL2 may supply compressed boil-off gas to a low-pressure engine through a part of a multi-stage compressor, for example, three compressors and a cooler.

The amount of evaporation gas generated in the storage tank is large, and even if it is supplied as fuel, the evaporation gas remains and is re-liquefied, or when LNG is supplied as fuel such as an engine and the evaporation gas is re-liquefied and processed, it is compressed through a multi-stage compressor. The system may further be provided with a reliquefaction line (RL) for cooling the boil-off gas by heat exchange with uncompressed boil-off gas generated from the storage tank and introduced into a multi-stage compressor, and then re-liquefying under reduced pressure to return to the storage tank. In the re-liquefaction line, a heat exchanger (500) for exchanging the compressed boil-off gas with uncompressed boil-off gas in a multi-stage compressor, an expansion valve (510) for adiabatic expansion of the boil-off gas cooled by heat exchange, and decompressed boil-off gas A device such as a separator 520 that separates and returns the separated liquefied gas to a storage tank may be provided.

On the other hand, the high-pressure engine can supply liquefied gas from the storage tank as fuel, if necessary. To this end, a third fuel supply line FL3 for supplying liquefied gas from the storage tank T to the high-pressure engine HE is provided. A third fuel supply line may be provided with a high pressure pump 300 for compressing liquefied gas and a vaporizer 310 for heating the compressed liquefied gas from a high pressure pump to a high pressure engine, and the third fuel in the storage tank. A stripping pump 320 for supplying liquefied gas to the supply line may be provided.

The fourth fuel supply line FL4 is branched from the third fuel supply line FL3 downstream of the carburetor 310 so as to supply compressed and vaporized liquefied gas to the fuel of the low pressure engine.

In the fourth fuel supply line FL4, a decompression valve 400 for decompressing liquefied gas to be supplied to a low pressure engine, and a heater 410 for heating the decompressed liquefied gas through a decompression valve according to the fuel supply temperature of the low pressure engine are added. It can be provided as.

The gas discharge line (PL) is connected to the fourth fuel supply line at the front end of the heater, and the boil-off gas that has joined from the gas discharge line to the fourth fuel supply line via a pressure regulating valve is heated in the heater and then used as fuel for the low-pressure engine. Can be supplied.

The second embodiment shown in FIG. 3 is a system in which a boiler B of a ship is added as a fuel consumption unit, and a supply line branched from the fourth fuel supply line downstream of the heater and connected to the boiler is shown in FIG. 3. It is provided additionally. To relieve the overpressure, the evaporated gas discharged from the first fuel supply line through the overpressure control valve 200 to the gas discharge line PL is supplied to the boiler B through the buffer tank 210 and the pressure control valve 220. Can be.

As in the first and second embodiments, in addition to the low-pressure engine and boiler of the ship, the fuel consumption unit on the ship may also be a gas combustion unit (GCU) (not shown), and supply evaporation gas that is not supplied to the low-pressure engine and boiler to the GCU. Can be burned and treated.

As described above, through the present embodiments, even if there is a change in the load of the overpressure engine, overpressure can be resolved through the gas discharge line to secure the safety of piping and devices, and to prevent the system from being stopped due to overpressure. In addition, the discharged boil-off gas can be used to prevent fuel waste by supplying fuel to the ship's fuel consumers, and to prevent contamination of liquefied gas cargo that may occur when returning boil-off gas to the storage tank.

The present invention is not limited to the above embodiments, and can be variously modified or modified within a range not departing from the technical gist of the present invention, which is obvious to a person skilled in the art to which the present invention pertains. It is done.

T: Storage tank HE: High pressure engine
LE: Low pressure engine
FL1: First fuel supply line FL2: Second fuel supply line
FL3: 3rd fuel supply line FL4: 4th fuel supply line
PL: Gas discharge line 100: Multi-stage compressor
200: overpressure control valve 210: buffer tank
220: pressure control valve 300: high pressure pump
310: carburetor 400: pressure reducing valve
410: heater 500: heat exchanger
510: expansion valve 520: separator

Claims (8)

A first fuel supply line for compressing the boil-off gas generated from the liquefied gas stored in the ship's storage tank and supplying it to the ship's high-pressure engine;
A gas discharge line that discharges a portion of the boil-off gas supplied to the high-pressure engine from the first fuel supply line to relieve overpressure caused by a load change of the high-pressure engine;
An overpressure control valve provided on the gas discharge line to control the discharge of the evaporated gas; And
It is provided downstream of the overpressure control valve of the gas discharge line to control the pressure of the evaporation gas; includes,
The pressure control valve adjusts the pressure of the boil-off gas to the fuel supply pressure of the ship's fuel consumer, and the boil-off gas is supplied to the ship's fuel consumer through the pressure control valve. According to claim 1,
The gas discharge line further comprises a buffer tank provided upstream of the pressure regulating valve to store the evaporated gas discharged from the first fuel supply line,
The fuel consumption system includes a ship's low pressure engine, and the evaporation gas can be supplied from the buffer tank to the low pressure engine through the pressure control valve. According to claim 2,
The fuel consumption system includes a ship's boiler, and the low-pressure engine and the boil-off gas not supplied to the boiler can be combusted in a GCU (Gas Combustion Unit). According to claim 2,
A multi-stage compressor provided on the first fuel supply line to compress the evaporation gas and alternately arranged with a plurality of compressors and coolers;
A second fuel supply line branching from the first fuel supply line and supplying the boil-off gas compressed through a part of the multi-stage compressor to the low-pressure engine; And
The fuel of the ship further comprising a reliquefaction line for generating the compressed boil-off gas from the storage tank by heat exchange with uncompressed boil-off gas to be introduced into the multi-stage compressor and returning it to the storage tank under reduced pressure. Supply system. The method of claim 4,
A third fuel supply line pumping the liquefied gas from the storage tank and supplying it to the high-pressure engine;
A high pressure pump provided on the third fuel supply line to compress the liquefied gas; And
And a carburetor provided on the third fuel supply line and heating the liquefied gas compressed by the high pressure pump to supply to the high pressure engine. The method of claim 5,
A fourth fuel supply line branching from the third fuel supply line downstream of the carburetor and supplying the compressed and vaporized liquefied gas to the low pressure engine;
A pressure reducing valve provided on the fourth fuel supply line to decompress the liquefied gas to be supplied to the low pressure engine; And
The heater is provided on the fourth fuel supply line and heats the liquefied gas decompressed through the pressure reducing valve according to the fuel supply temperature of the low pressure engine.
The gas discharge line is connected to the fourth fuel supply line from the front end of the heater fuel supply system of the ship. Compress the evaporated gas generated from the liquefied gas stored in the ship's storage tank and supply it to the ship's high pressure engine
A part of the boil-off gas supplied to the high-pressure engine is discharged from a supply line to eliminate overpressure caused by a load change of the high-pressure engine,
A pressure control valve for adjusting the pressure of the boil-off gas is provided on the line from which the boil-off gas is discharged from the supply line, the pressure of the pressure control valve is set to the fuel supply pressure of the fuel consumption on board, and discharged from the supply line. The boil-off gas is supplied to the ship through the pressure control valve fuel supply method of the vessel, characterized in that for supply. The method of claim 7,
The fuel consumption unit includes a low-pressure engine and a boiler of the ship, and the evaporation gas supplied to the low-pressure engine and the boiler can be combusted in the ship's GCU, characterized in that the ship's fuel supply method.

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