KR20210111386A - Fuel Gas Supply System for Liquefied Gas Fueled Ship - Google Patents

Abstract

The present invention relates to a liquefied gas fuel supply system for a vessel using liquefied gas as fuel for an engine and, more specifically, to a fuel supply system for a liquefied gas fuel vessel, capable of overcoming difficulty in driving caused by a pressure change in fuel. According to the present invention, in regard to the fuel supply system for a liquefied gas fuel vessel using liquefied gas as fuel for an engine, the engine, which is a high-pressure gas injection engine, includes: a high-pressure pump compressing the liquefied gas with high pressure required for the engine; a high-pressure evaporator evaporating the high-pressure liquefied gas compressed by the high-pressure pump; and a pressure control means installed between the engine and the high-pressure evaporator, and provided to control piping pressure between the engine and the high-pressure evaporator. The pressure control means includes a buffer tank for temporarily storing the high-pressure fuel gas evaporated by the high-pressure evaporator. Thus, the high-pressure fuel gas discharged from the buffer tank is supplied as fuel for the engine to keep pressure between the high-pressure evaporator and the engine constant.

Description

Fuel Gas Supply System for Liquefied Gas Fueled Ship

The present invention relates to a fuel supply system for a liquefied gas fuel vessel capable of overcoming difficulties in operation due to a change in fuel pressure in a liquefied gas fuel supply system for a vessel using liquefied gas as an engine fuel.

From January 1, 2020, the International Maritime Organization has decided to implement regulations to significantly strengthen the upper limit of sulfur content in ship fuel oil from 3.5% to 0.5%. In order to meet the IMO 2020 standard, which is a strengthened environmental regulation, an exhaust gas purification device worth 5 to 10 billion won must be installed on the ship, or the fuel for the propulsion device must be used for fuel with low sulfur, which is 50% more expensive than the existing high sulfur oil. A propulsion device that can change the flow path or use LNG (Liquefied Natural Gas) as fuel should be applied.

Gas propulsion engines applied to LNG fueled ships (LFS) that use LNG as fuel reduce the generation of carbon dioxide, nitrogen oxides (NO _x ), sulfur oxides (SO _x ), etc., compared to diesel engines of the same output. It also satisfies economic feasibility as the price per unit of heat is considerably lower than that of ship fuel oil such as diesel oil.

Examples of marine engines that can use LNG (natural gas) as fuel include DF engines (DFDE (Dual Fuel Diesel Electric), DFDG (Dual Fuel Diesel Generator)), X-DF (eXtra long stroke Dual Fuel) engines, and ME- There are dual fuel engines such as the GI engine (MAN Electronic Gas-Injection Engine).

Among them, the ME-GI engine, as the main engine for propulsion, consists of two strokes, and operates based on a diesel cycle in which high-pressure natural gas of around 300 barg is directly injected into the combustion chamber near the top dead center of the piston. .

When a ME-GI engine that uses 300 barg of high-pressure natural gas as a fuel is adopted as a propulsion engine, a fuel gas supply system (FGSS) that supplies natural gas fuel to an LNG-fueled vessel with an ME-GI engine this should be provided

A fuel supply system for supplying fuel to a high-pressure injection engine such as an ME-GI engine includes a high-pressure pump that compresses LNG stored in an LNG fuel tank to the pressure required by the ME-GI engine, that is, about 300 barg, and a high-pressure pump. It essentially includes a high-pressure vaporizer for vaporizing high-pressure LNG of about 300 barg compressed by the

In order to compress LNG to a high pressure of 300 barg, a cylinder reciprocating type pump that compresses LNG using a piston as a high pressure pump should be applied.

Such a high-pressure fuel supply system is inherently dangerous in that it has to operate a fluid compressed at high pressure. In particular, when the engine load is changed abruptly or the fuel oil mode is switched to the fuel oil mode, the operation of the high-pressure pump is caused by the rapid pressure fluctuation. This is often stopped, and there is a problem in that the remaining pressure must be relieved.

Accordingly, the present invention is intended to solve the above problems, in a fuel supply system for supplying high-pressure liquefied gas fuel to a high-pressure gas injection engine, a liquefied gas fuel vessel capable of overcoming operational difficulties due to fuel pressure fluctuations. An object of the present invention is to provide a fuel supply system.

According to one aspect of the present invention for achieving the above object, in the fuel supply system of a liquefied gas fuel ship using liquefied gas as a fuel for an engine, the engine is a high-pressure gas injection engine, and the liquefied gas is used as the engine a high-pressure pump that compresses to the high pressure required by the a high-pressure vaporizer for vaporizing the high-pressure liquefied gas compressed by the high-pressure pump; and a pressure regulating means installed between the high-pressure carburetor and the engine, for regulating the pipe pressure between the high-pressure carburetor and the engine, wherein the pressure regulating means temporarily stores the high-pressure fuel gas vaporized in the high-pressure carburetor. Including, the high-pressure fuel gas discharged from the buffer tank is supplied to the fuel of the engine to maintain a constant pressure between the high-pressure carburetor and the engine, a fuel supply system for a liquefied gas fuel vessel is provided do.

Preferably, the pressure regulating means may include a high-pressure regulating valve whose opening and closing is controlled to discharge the residual high-pressure fuel gas remaining between the high-pressure carburetor and the engine.

Preferably, a pressure relief line branched from the fuel supply line between the high-pressure carburetor and the engine and connected to a liquefied gas storage tank for storing the liquefied gas; further comprising, wherein the high-pressure control valve is installed in the pressure relief line can be

Preferably, the buffer tank is installed between the high-pressure control valve and the high-pressure carburetor, and may temporarily store the high-pressure fuel gas vaporized in the high-pressure carburetor.

Preferably, the buffer tank may be a pressure vessel.

Preferably, it further comprises a pressure measuring unit for measuring the pressure between the high-pressure carburetor and the pressure regulating means, wherein the pressure regulating means operates when the pressure measurement value of the pressure measuring unit exceeds a safe range to operate with the high-pressure carburetor and the pressure regulating means. It can relieve the overpressure between the engines.

Preferably, the pressure regulating means maintains the pipe pressure between the high-pressure carburetor and the engine within a certain range, and discharges the high-pressure fuel gas between the high-pressure carburetor and the engine when the load of the engine changes and the fuel mode is switched. can be operated to make

The fuel supply system for a liquefied gas fuel ship according to the present invention, in the fuel supply system for supplying high-pressure liquefied gas fuel to a high-pressure gas injection engine, has difficulties in operating control due to fluctuations in fuel pressure and frequent failure of the high-pressure pump can solve

In addition, it is possible to solve the problem of stopping the high-pressure pump by smoothly relieving the pressure in the pipe when the pressure fluctuation occurs.

In particular, by providing the buffer tank downstream of the high-pressure pump, it is possible to solve the problem of not resolving the pressure due to frequent malfunction of the high-pressure control valve, and it is possible to solve the malfunction of the high-pressure pump.

In addition, by providing a buffer tank downstream of the high-pressure pump to maintain the pressure between the high-pressure carburetor and the pressure control valve in a certain range, the disadvantages according to the sensitivity of the operation response of the high-pressure control valve are compensated, and the system is sensitive to pressure control. It can be improved to avoid

1 is a schematic diagram illustrating a fuel supply system of a liquefied gas fuel vessel.
2 is a schematic diagram illustrating a fuel supply system of a liquefied gas fuel ship according to an 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 illustrating preferred embodiments of the present invention and the contents described in the accompanying drawings.

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 signs to the elements of each drawing, it should be noted that only the same elements are indicated by the same reference signs as possible even if they are indicated on different drawings.

Liquefied gas in an embodiment of the present invention to be described later may be applied to various liquefied gases, for example, LNG (Liquefied Natural Gas), LEG (Liquefied Ethane Gas), LPG (Liquefied Petroleum Gas), liquefied gas It may be a liquefied petrochemical gas such as ethylene gas (Liquefied Ethylene Gas) or liquefied propylene gas (Liquefied Propylene Gas). Alternatively, liquid gas such as liquefied carbon dioxide, liquefied hydrogen or liquefied ammonia may be used. However, in the embodiments to be described later, an example in which LNG, which is a representative liquefied gas, is applied will be described.

In addition, in the embodiment to be described later, the ship is described by taking the case of a LNG carrier that transports liquefied natural gas as cargo, but the present invention is an LNG FSRU (Floating LNG FSRU) equipped with a storage tank for storing liquefied natural gas. Storage Regasification Unit), LNG FPSO (Floating Production Storage Offloading), LNG RV (Regasification Vessel), etc. The present invention is provided with an LNG storage tank, and is produced by forcibly vaporizing BOG and/or LNG generated by natural gasification of LNG. It can be applied to all LNG fueled ships equipped with engines that can use regasified gas, that is, natural gas as fuel.

In addition, in an embodiment of the present invention, which will be described later, the engine may be a gas fuel engine capable of using natural gas as a fuel as a dual fuel among engines used in ships, a high-pressure gas injection engine, a medium-pressure gas injection engine, and a low-pressure gas engine. It may include any one or more of the injection engines.

The high-pressure gas injection engine is an engine using gas fuel of about 100 bar to 400 bar, or about 150 bar or more, preferably about 300 bar, for example, an ME-GI engine will be described as an example. In addition, the medium pressure gas injection engine may be an engine using gas fuel of about 10 bar to 20 bar, preferably about 16 bar, for example, an X-DF engine, and the low pressure gas injection engine is about 5 bar to 10 bar , preferably an engine using gas fuel of about 6.5 bar, for example, a DF engine, a DFDG engine, or a DFGE engine.

ME-GI (MAN Electronic Gas-Injection Engine) engine consists of two strokes, and operates based on a diesel cycle in which high-pressure natural gas near 300 bar is directly injected into the combustion chamber near top dead center of the piston. .

The X-DF (eXtra long stroke Dual Fuel) engine is composed of two strokes, uses about 16 bar of natural gas as fuel, and operates on an auto cycle basis.

The DF engine (DFDE (Dual Fuel Diesel Electric), DFDG (Dual Fuel Diesel Generator, or DFGE)) is composed of four strokes and injects natural gas with a relatively low pressure of 6.5 bar into the combustion air inlet. It operates based on the Otto Cycle, which compresses the piston as it rises.

In one embodiment of the present invention, which will be described later, the ME-GI engine is applied as the main engine for propulsion and the DFDE is applied as the auxiliary engine for power generation as an example.

In this embodiment, the engine may be operated in a gas mode in which energy is generated using gas as a fuel, and in a fuel oil mode in which energy is generated using fuel oil such as Marine Diesel Oil (MDO) as a fuel.

In addition, a ship's LNG fuel supply system (FGSS) includes a so-called HiCOM that supplies boil-off gas generated by natural vaporization of LNG as fuel for the engine, a high-pressure pump, and a vaporizer. It may include a so-called HiVAR (HiVAR) that forcibly vaporizes LNG and supplies natural gas as an engine fuel.

Hicom includes a compressor that compresses boil-off gas discharged from the LNG storage tank to the pressure required by the ME-GI engine, that is, about 300 bar, and supplies it to the ME-GI engine.

In addition, Hicom is a partial reliquefaction system (PRS; Partial Reliquefaction System) that reliquefies compressed BOG in an amount exceeding the fuel demand required by the ME-GI engine among BOG compressed by the compressor and recovers it to an LNG storage tank. It can be configured in conjunction with the Reliquefaction System).

The partial reliquefaction system includes a heat exchanger for cooling the compressed BOG by exchanging the compressed BOG with the BOG introduced to the compressor before compression, a decompression device for decompressing the BOG cooled in the heat exchanger, and a decompression device. A gas-liquid separator that separates the condensed re-liquefied BOG and non-condensed BOG to recover the re-liquefied BOG to the LNG storage tank and joins the non-condensed BOG to the BOG flow before compression introduced into the heat exchanger. have.

Hereinafter, a fuel supply system of a liquefied gas fuel vessel according to an embodiment of the present invention will be described with reference to FIGS. 1 and 2 . 1 and 2 illustrate only a partial configuration of the hi-bar, the detailed configuration of the hi-com and a detailed method of supplying the forced vaporization gas as a fuel of the engine using the hi-com will be omitted.

First, referring to FIG. 1 , the fuel supply system of a liquefied gas fuel ship includes an LNG storage tank 100 for storing LNG; a high-pressure pump 200 capable of compressing the boil-off gas discharged from the LNG storage tank 100 to about 150 bar to 300 bar, which is the pressure required by the main engine, that is, the ME-GI engine; a high-pressure vaporizer 300 for vaporizing the LNG compressed by the high-pressure pump 200; and a fuel supply line (FL) connecting the high-pressure carburetor 300 and the ME-GI engine so that the high-pressure natural gas vaporized in the high-pressure carburetor 300 is supplied to the ME-GI engine.

Although only one LNG storage tank 100 is shown in the drawing, a plurality of LNG storage tanks 100 of this embodiment may be installed.

In addition, one or more feed pumps (not provided with reference numerals) for discharging the LNG stored in the LNG storage tank 100 to the outside may be installed in the LNG storage tank 100 . The feed pump may be a semi-submersible pump.

In addition, it is installed between the high-pressure carburetor 300 and the ME-GI engine, and discharges the high-pressure natural gas remaining between the high-pressure carburetor 300 and the ME-GI engine by opening and closing the high-pressure carburetor 300 and the ME. -High pressure control valve 400 for controlling the pressure in the pipe between the GI engine; further includes.

Opening and closing of the high-pressure control valve 400 may be controlled according to a pressure measurement value of the pressure measurement unit PIC that measures the pressure between the high-pressure carburetor 300 and the ME-GI engine. That is, when the pressure measurement value of the pressure measurement unit exceeds the preset safety range, the high pressure control valve 400 is opened, and natural gas of high pressure in the fuel supply line FL between the high pressure carburetor 300 and the ME-GI engine. can be discharged to the outside. Meanwhile, when the pressure of the fuel supply line FL between the high-pressure carburetor 300 and the ME-GI engine is normalized, the high-pressure control valve 400 may be closed again.

According to this embodiment, as shown in FIG. 1 , a pressure relief line PL branched from the fuel supply line FL between the high-pressure carburetor 300 and the ME-GI engine and connected to the LNG storage tank 100 . Including further, the high pressure control valve 400 may be installed in the pressure relief line (PL).

In this way, by installing the high-pressure control valve 400, from the high-pressure natural gas vaporized in the high-pressure carburetor 300, the high-pressure natural gas, etc. remaining that cannot be supplied to the ME-GI engine is discharged to eliminate the pressure increase, It is possible to prevent excessive increase in the pressure in the pipe between the high-pressure carburetor 300 and the ME-GI engine.

The safe range pressure of this embodiment may be determined according to the load of the ME-GI engine.

In addition, opening and closing of the high pressure control valve 400 may be controlled according to a load change or a mode change of the ME-GI engine.

For example, when the load of the ME-GI engine is suddenly lowered and some of the high-pressure natural gas vaporized in the high-pressure carburetor 300 or the ME-GI engine cannot be supplied to the ME-GI engine, the high-pressure control valve 400 is opened and closed so that the residual High-pressure natural gas may be discharged from the fuel supply line FL.

In addition, the ME-GI engine is a dual fuel engine that can be operated in a gas mode using gas as a fuel and a fuel oil mode using fuel oil as a fuel. For example, the high pressure remaining in the fuel supply line FL between the high-pressure carburetor 300 and the ME-GI engine by opening and closing the high-pressure control valve 400 when it is operated in the gas mode and switched to the fuel oil mode Natural gas can be discharged from the fuel supply line (FL).

However, when the solid line is applied, the high pressure control valve 400 has a low sensitivity of the operation reaction, so that it does not operate (open) properly at an appropriate time frequently occurs. In this way, if the high-pressure control valve 400 does not operate in time, that is, if it is not opened in time and the high-pressure natural gas cannot be discharged from the fuel supply line FL, the pressure inside the pipe cannot be relieved and the operation of the high-pressure pump 200 is not performed. There is a problem in that the normal operation of the fuel supply system such as the high-pressure pump 200 is difficult due to pressure fluctuations such as stopping and malfunctioning.

Therefore, according to this embodiment, as shown in FIG. 2, the buffer tank 500 is installed between the high-pressure carburetor 300 and the high-pressure control valve 400, and can temporarily store high-pressure natural gas in a predetermined capacity; may include more.

The buffer tank 500 of this embodiment may be provided as a pressure vessel (buffer volume).

The high-pressure natural gas vaporized in the high-pressure vaporizer 300 is supplied to the buffer tank 500 , the buffer tank 500 is maintained at a constant pressure, and the high-pressure boil-off gas discharged from the buffer tank 500 is fed to the ME-GI engine. is supplied

As described above, by installing the buffer tank 500 downstream of the high-pressure carburetor 300 and upstream of the high-pressure control valve 400 , it is possible to buffer abrupt pressure fluctuations due to load changes or mode changes of the ME-GI engine.

For example, even if the high-pressure control valve 400 does not open even though the high-pressure natural gas in the fuel supply line FL needs to be discharged, the flow rate and/or speed of the high-pressure natural gas discharged from the buffer tank 500 . By adjusting , the pressure of the fuel supply line FL between the high-pressure carburetor 300 and the ME-GI engine can be stably maintained within a desired pressure range.

Both the buffer tank 500 and the high pressure control valve 400 of this embodiment may be provided, or only the buffer tank 500 may be provided.

When only the buffer tank 500 is provided, the buffer tank 500 is installed between the high-pressure carburetor 400 and the ME-GI engine.

When both the buffer tank 500 and the high pressure control valve 400 are provided, the buffer tank 500 is a point at which the pressure relief line PL in which the high pressure control valve 400 is installed is branched from the fuel supply line FL. It may be installed upstream of, that is, the high-pressure vaporizer 300 side.

Also, the pressure measuring unit PIC may be installed upstream of the buffer tank 500 . According to the present embodiment, the pressure measurement value of the pressure measurement unit PIC, that is, the pressure of the fuel supply line FL between the buffer tank 500 and the ME-GI engine is measured, and the pressure measurement value exceeds the safe range. In this case, it is possible to control the high pressure control valve 400 to be opened.

The present invention is not limited to the above embodiments, and it is apparent to those skilled in the art that various modifications or variations can be implemented without departing from the technical gist of the present invention. did it

100: LNG storage tank
200: high pressure pump
300: high pressure carburetor
400: high pressure control valve
500: buffer tank
PIC: pressure measuring unit
FL : fuel supply line
PL : pressure relief line

Claims (7)

In the fuel supply system of a liquefied gas fuel ship using liquefied gas as an engine fuel,
The engine is a high-pressure gas injection engine,
a high-pressure pump for compressing the liquefied gas to a high pressure required by the engine;
a high-pressure vaporizer for vaporizing the high-pressure liquefied gas compressed by the high-pressure pump; and
It is installed between the high-pressure carburetor and the engine, and includes a pressure regulating means for regulating the pipe pressure between the high-pressure carburetor and the engine.
The pressure regulating means,
Including; a buffer tank for temporarily storing the high-pressure fuel gas vaporized in the high-pressure carburetor
The high-pressure fuel gas discharged from the buffer tank is supplied to the fuel of the engine to maintain a constant pressure between the high-pressure carburetor and the engine, a fuel supply system for a liquefied gas fuel vessel. The method according to claim 1,
The pressure regulating means,
A fuel supply system for a liquefied gas fuel vessel, including; a high-pressure control valve that opens and closes to discharge the residual high-pressure fuel gas remaining between the high-pressure carburetor and the engine. 3. The method according to claim 2,
A pressure relief line branched from the fuel supply line between the high-pressure carburetor and the engine and connected to a liquefied gas storage tank for storing the liquefied gas; further comprising,
The high pressure control valve is installed in the pressure relief line, the fuel supply system of the liquefied gas fuel vessel. 3. The method according to claim 2,
The buffer tank is
A fuel supply system for a liquefied gas fuel vessel installed between the high-pressure control valve and the high-pressure carburetor and temporarily storing the high-pressure fuel gas vaporized in the high-pressure carburetor. The method according to claim 1,
The buffer tank is a pressure vessel, the fuel supply system of the liquefied gas fuel vessel. The method according to claim 1,
Further comprising; a pressure measuring unit for measuring the pressure between the high-pressure vaporizer and the pressure control means;
The pressure regulating means operates when the pressure measurement value of the pressure measuring unit exceeds a safe range to relieve the overpressure between the high-pressure carburetor and the engine, the fuel supply system of the liquefied gas fuel vessel. The method according to claim 1,
The pressure regulating means maintains the pipe pressure between the high-pressure carburetor and the engine within a certain range, and is operated to discharge the high-pressure fuel gas between the high-pressure carburetor and the engine when the load of the engine changes and the fuel mode is switched. , liquefied gas fueled ship fuel supply system.

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