KR102234666B1 - Apparatus for supplying low-pressure fuel gas in ship - Google Patents

Abstract

The present invention provides a low pressure fuel supply device for a ship. The low pressure fuel supply device of the ship of the present invention includes a storage tank equipped with liquefied gas; A compression unit receiving and compressing the vaporized gas generated from the storage tank; A dual fuel engine that receives and uses the vaporized gas compressed from the compression unit; A supply pump installed inside the storage tank; And a forced evaporator forcibly evaporating the liquefied gas supplied from the supply pump into vaporized gas usable in the dual fuel engine; The supply pump may compress the liquefied gas at a pressure required by the dual fuel engine and supply it to the forced evaporator.

Description

Ship's low pressure fuel supply system {APPARATUS FOR SUPPLYING LOW-PRESSURE FUEL GAS IN SHIP}

The present invention relates to a ship, and more particularly, to a low pressure fuel supply device in a ship having a storage tank of liquefied natural gas (LNG).

In general, liquefied natural gas (Liquefied Natural Gas, hereinafter referred to as "LNG") is a colorless and transparent liquid obtained by liquefying natural gas containing methane as its main component by cooling to about -162°C. LNG has a volume of about 1/600 compared to natural gas. Therefore, when transporting natural gas by liquefying it into LNG, it can be transported very efficiently. For example, an LNG carrier capable of transporting (transporting) LNG by sea is being used.

Since the liquefaction temperature of natural gas is a cryogenic temperature of -163°C at normal pressure, LNG is easily evaporated even if the temperature is slightly higher than -163°C at normal pressure. Although the LNG storage tank of an LNG carrier is insulated, external heat is continuously transferred to the LNG storage tank, so during the LNG transportation process by the LNG carrier, LNG is continuously evaporated naturally within the LNG storage tank. Boil off gas (BOG) is generated in the storage tank.

BOG from the storage tank is mainly processed by using it as engine fuel, and a system for processing this is called a fuel gas supply system (FGSS). The conventional DFDE engine has recently been newly developed as an X-DF engine with better efficiency, and accordingly, the necessity to newly construct an FGSS is emerging.

An embodiment of the present invention is to provide a low-pressure fuel supply device for a ship that can efficiently use the vaporized gas.

An embodiment of the present invention is to provide a low pressure fuel supply device for a ship with improved operating efficiency of a compressor.

An embodiment of the present invention is to provide a low-pressure fuel supply device for a ship that can reduce the consumption of electrical energy.

The problem to be solved by the present invention is not limited thereto, and other problems that are not mentioned will be clearly understood by those skilled in the art from the following description.

According to an aspect of the present invention, a storage tank provided with liquefied gas; A compression unit receiving and compressing the vaporized gas generated from the storage tank; A dual fuel engine that receives and uses the vaporized gas compressed from the compression unit; A supply pump for pressurizing the liquefied gas in the storage tank; And a forced evaporator forcibly evaporating the liquefied gas supplied from the supply pump into vaporized gas usable in the dual fuel engine; The supply pump may be provided with a low-pressure fuel supply device for a ship that compresses liquefied gas at a pressure required by the dual fuel engine and supplies it to the forced evaporator.

In addition, the compression unit may include a main compression unit in which a plurality of compressors are arranged in series.

The compression unit may further include a heat exchanger installed downstream of the compressor to exchange heat with the compressed vaporized gas.

In addition, the gas combustion unit further comprises a gas combustion unit that burns excess vaporized gas generated when the amount of boil off gas generated in the storage tank is greater than the amount of fuel consumed in the dual fuel engine, and the compression unit It may further include a sub-compression unit that bypasses the unit to supply the excess vaporized gas to the gas combustion unit and has a compressor less than the main compression unit.

In addition, a water separator for separating water from the vaporized gas flowing into the dual fuel engine from the forced evaporator may be further included.

According to an aspect of the present invention, a storage tank provided with liquefied gas; A vaporized gas supply line for supplying a vaporized gas generated from the storage tank to a dual fuel engine; A main compression unit installed on the vaporized gas supply line and compressing the vaporized gas to a pressure required by the dual fuel engine; A supply pump installed inside the storage tank to compress and supply liquefied gas to a pressure required by the dual fuel engine; A direct supply line for supplying the liquefied gas supplied from the supply pump to the dual fuel engine; A low-pressure fuel supply device for a ship including a forced evaporator installed on the direct supply line and forcibly evaporating liquefied gas into vaporized gas usable in the dual fuel engine may be provided.

In addition, a sub-gasification gas supply line branched from the vaporized gas supply line may further include a sub vaporized gas supply line for supplying boil off gas generated from the storage tank to the gas combustion unit.

In addition, a water separator installed on the direct supply line may further include a water separator for separating water from the forced vaporization gas supplied from the forced evaporator to the dual fuel engine.

In addition, the main compression unit may include a plurality of compressors arranged in series; And a heat exchanger that performs heat exchange with the vaporized gas compressed by the compressor.

In addition, further comprising a sub compression unit installed in the sub vaporized gas supply line, compressing the vaporized gas to a pressure required by the gas combustion unit; The sub compression unit may have fewer compressors than the main compression unit.

In addition, a vaporized gas branch line branched from the vaporized gas supply line to supply vaporized gas to the auxiliary engine may be further included, and a pressure reducing valve may be installed in the vaporized gas branch line.

Embodiments of the present invention have a special effect of minimizing the burden on maintenance and maintenance and economic overload caused by the installation of an expensive compressor.

Embodiments of the present invention increase energy saving efficiency by compressing the liquefied gas at the pressure required by the dual fuel engine and supplying it to the dual fuel engine by compressing the liquefied gas at the pressure required by the dual fuel engine without passing through a multi-stage compressor that consumes a lot of electric energy when sailing in a ballast state It has a special effect that can be.

Embodiments of the present invention have a special effect of reducing electrical energy consumption due to unnecessary gas compression by compressing and supplying excess vaporized gas to only the minimum pressure required by the gas combustion unit.

1 is a block diagram showing a low pressure fuel supply device for a ship according to an embodiment of the present invention.
2 is a block diagram showing a low-pressure fuel supply device for a ship according to another embodiment of the present invention.

In the present invention, various transformations may be applied and various embodiments may be provided, and specific embodiments will be illustrated in the drawings and will be described in detail in the detailed description. However, this is not intended to limit the present invention to a specific embodiment, it should be understood to include all conversions, equivalents, and substitutes included in the spirit and scope of the present invention. In describing the present invention, when it is determined that a detailed description of a related known technology may obscure the subject matter of the present invention, a detailed description thereof will be omitted.

The terms used in the present application are only used to describe specific embodiments, and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In the present application, terms such as "comprise" or "have" are intended to designate the presence of features, numbers, steps, actions, components, parts, or combinations thereof described in the specification, but one or more other features. It is to be understood that the presence or addition of elements or numbers, steps, actions, components, parts, or combinations thereof does not preclude in advance.

Terms such as first and second may be used to describe various elements, but the elements should not be limited by the terms. The above terms are used only for the purpose of distinguishing one component from another component.

Hereinafter, embodiments according to the present invention will be described in detail with reference to the accompanying drawings. In the description with reference to the accompanying drawings, the same or corresponding components regardless of the reference numerals are given the same reference numerals, and duplicates thereof. Description will be omitted.

1 is a block diagram showing a low pressure fuel supply device for a ship according to an embodiment of the present invention.

The main feature of this embodiment is that the liquefied gas is compressed to a pressure (for example, 17 bara) required by the X-DF engine (hereinafter referred to as a dual fuel engine) using a pump rather than a compressor that requires a lot of electrical energy. It is characterized by the main feature.

Referring to FIG. 1, the low pressure fuel supply device 10 of the ship includes a storage tank 100, a vaporized gas supply line 200, a main compression unit 300, a supply pump 400, a direct supply line 500, and It includes a forced evaporator 600, a sub vaporized gas supply line 700 and a sub compression unit 800.

In the low-pressure fuel supply device 10 of the ship of this embodiment, a storage tank 100 equipped with a low-temperature liquefied gas is provided on an LNG carrier. In these embodiments, an LNG carrier is described as an example, but the core idea of the present invention is not limited thereto, and a ship with an LNG storage tank and a floating offshore structure, that is, LNG-FPSO (Floating Production Storage). and Offloading), LNG-RV (Regasification Vessel), LNG-FSRU (Floating Storage Regasification Unit), etc.

A plurality of storage tanks 100 may be provided, and in this embodiment, the first to fourth tanks 102, 104, 106, and 108 will be described as being provided. In the first to fourth tanks 102, 104, 106, and 108, LNG at a low temperature (-163° C.) may be stored therein. The number of the first to fourth tanks 102, 104, 106, and 108 is variable and is not limited to the number shown in FIG. 1. The storage tanks 102, 104, 106, and 108 may be membrane-type storage tanks in addition to a plurality of independent storage tanks as in this embodiment. A supply pump 108 for discharging liquefied natural gas (LNG) to the outside is installed at the bottom of the two low storage tanks 102 and 104 of the storage tanks.

The storage tank 100 naturally generates vaporized gas (BOG) therein, and the vaporized gas is a main compression unit 200 through a pipe 110 provided in each of the first to fourth tanks 102, 104, 106, and 108. ) May be supplied to the vaporized gas supply line 200 connected to.

The storage tank 100 may have a predetermined size and shape, and LNG may be filled therein. The vaporized gas may be supplied as fuel for the operation of the dual fuel engine 20. The dual fuel engine 20 may be operated by receiving gasified gas, liquefied gas forcibly vaporized and diesel fuel as operable fuel.

The vaporized gas generated in the storage tank 100 may be supplied to the dual fuel engine 20 through the vaporized gas supply line 200. A water separator 210 and a main compression unit 300 are installed on the vaporized gas supply line 200. In addition, the vaporized gas generated in the storage tank 100 may be supplied to the gas combustion unit 30 through the sub vaporized gas supply line 700. A sub compression unit 800 is installed on the sub vaporized gas supply line 700. That is, the vaporized gas vaporized from the storage tank 100 can be selectively supplied to the main compression unit 300 or the sub compression unit 800 by switching a switching valve (not shown).

The main compression unit 300 is a device that compresses the vaporized gas generated from the storage tank 100 to a pressure required by the dual fuel engine 20. The main compression unit 300 may include a multistage compressor capable of compressing at least two stages or more according to the temperature and the amount of gas of the vaporized gas. In this embodiment, a five-stage compressor may be provided and may be connected to each other in series. The reason why the main compression unit 200 has a five-stage compressor arranged in multiple stages is that the pressure of the vaporized gas supplied to the dual fuel engine 20 is reduced to the required pressure for stable operation in the dual fuel engine 20 (for example, It is to increase to 17 bara) and supply.

Meanwhile, the main compression unit 300 may further include a heat exchanger 310 installed downstream of the compressor to exchange heat with the compressed vaporized gas. The heat exchanger 310 may function to maintain the temperature of the vaporized gas compressed through the compressor at the temperature required by the dual fuel engine 20. For example, the heat exchanger 310 may raise the temperature of the evaporative vapor moved via the compressor when the temperature is low, and lower the temperature to the temperature required by the dual fuel engine 20 when the temperature is high. Here, the temperature required by the dual fuel engine 20 is variable according to the type and specification of the engine, and refers to a temperature range in which the dual fuel engine 20 can stably operate. The heat exchanger 310 may use water (seawater) as a refrigerant for heat exchange.

The dual fuel engine 20 receives vaporized gas having a desired pressure and temperature through the multistage compressors through the vaporized gas supply line 200. The dual fuel engine 20 provides an energy source for propelling a liquefied natural gas carrier using gas vaporized from the storage tank 100.

The dual fuel engine 20 is an engine capable of driving a steam turbine by burning vaporized gas to generate water vapor, or selectively using fossil fuel and vaporized gas as fuel. For reference, the dual fuel engine 20 does not use a high-pressure fuel gas (a pressure of several hundred bara) like a MEGI engine, but uses a low-pressure fuel gas compressed to about several to tens of bara.

The vaporized gas branch line 290 is branched from the vaporized gas supply line 200 to supply vaporized gas to the auxiliary engine 40. A pressure reducing valve 280 may be installed in the vaporized gas branch line 290.

The sub vaporized gas supply line 700 is branched from between the water separator 210 and the main compression unit 300 and is connected to the gas combustion unit 30. The gas combustion unit 30 burns excess vaporized gas generated when the amount of vaporized gas generated in the storage tank 100 is greater than the amount of fuel consumed by the dual fuel engine 20.

The sub compression unit 800 is installed on the sub vaporized gas supply line 700. The sub compression unit 800 is for compressing the vaporized gas to a pressure required by the gas combustion unit 30, and may include a multistage compressor capable of compressing at least two stages. In the present embodiment, a five-stage compressor has been shown and described, but in some cases, it may be applied as a two-stage compressor as shown in FIG. 2 and used as a hybrid type.

The direct supply line 500 is provided to supply liquid liquefied gas (LNG) as fuel gas required by the dual fuel engine 20. The direct supply line 500 is a line that supplies the liquefied gas supplied from the supply pump 400 to the dual fuel engine 20. A forced evaporator 600 and a water separator 510 are sequentially installed on the direct supply line 500. The forced evaporator 600 forcibly evaporates the liquefied gas into a vaporized gas that can be used in a dual fuel engine.

The liquefied gas stored in the storage tank 100 is discharged from the supply pump 400 in a compressed state at a pressure required by the dual fuel engine 20 and transferred along the direct supply line 500. The liquefied gas in a continuously compressed state is vaporized in the forced evaporator 600, and after the moisture is removed in the water separator 510, it is supplied to the dual fuel engine 20.

For reference, ships such as LNG carriers and LNG RVs are used to transport LNG from production to consumption, so when operating from production to consumption, operate in a Laden state full of LNG in a storage tank, and LNG When returning to the production site after unloading, the storage tank is operated in a ballast state where the storage tank is almost empty. The amount of boil-off gas is relatively large due to the large amount of LNG in the laid state, and the amount of boil-off gas is relatively small due to the small amount of LNG in the ballast state.

As in the present invention, in the laid-down state with a large amount of vaporized gas, the gas is compressed in the main compression unit 300 through the vaporized gas supply line 200, and then the fuel is supplied to the dual fuel engine 20, and the amount of vaporized gas is generated. In this low ballast state, the supply pump 400 compresses the liquid liquefied gas and then vaporizes it in the forced carburetor 600 to supply fuel to the dual fuel engine 20.

As described above, the present invention uses the supply pump 400 to compress the liquid liquefied gas and supply it to the dual fuel engine 20, so a multi-stage that requires relatively more electrical energy than the supply pump 400 Energy consumption can be significantly reduced compared to using a compressor.

2 is a block diagram showing a low pressure fuel supply device for a ship according to another embodiment of the present invention.

Referring to FIG. 2, in the low pressure fuel supply device 10a of a ship according to another embodiment, the compressor of the sub compression unit 800a installed on the sub vaporized gas supply line 700 is a two-stage compressor, not a five-stage compressor. It is different from the low pressure fuel supply device 10 of the ship of FIG. 1 in that it is composed of.

That is, the sub vaporized gas supply line 700 and the sub compression unit 800a can be used as a hybrid type so that they can be used as a binary concept, and in this case, initial facility investment cost can be reduced.

The above description is merely illustrative of the technical idea of the present invention, and those of ordinary skill in the art to which the present invention pertains will be able to make various modifications and variations without departing from the essential characteristics of the present invention. Accordingly, the embodiments disclosed in the present invention are not intended to limit the technical idea of the present invention, but to explain the technical idea, and the scope of the technical idea of the present invention is not limited by these embodiments. The scope of protection of the present invention should be interpreted by the following claims, and all technical ideas within the scope equivalent thereto should be construed as being included in the scope of the present invention.

100: storage tank 200: vaporized gas supply line
300: main compression unit 400: supply pump
500: direct supply line 600: forced evaporator
700: sub vaporized gas supply line 800: sub compression unit

Claims (11)

In the ship's low pressure fuel supply system:
A storage tank equipped with liquefied gas;
A vaporized gas supply line for supplying a vaporized gas generated from the storage tank to a dual fuel engine;
A main compression unit installed on the vaporized gas supply line and compressing the vaporized gas to a pressure required by the dual fuel engine;
A supply line supply pump by compressing the liquefied gas at a pressure required by the dual fuel engine;
A gas combustion unit for burning excess vaporized gas generated when the amount of vaporized gas generated in the storage tank is greater than the amount of fuel consumed in the dual fuel engine;
A forced evaporator forcibly evaporating the liquefied gas supplied from the supply pump into a vaporized gas usable in the dual fuel engine;
A water separator for separating water from the vaporized gas flowing into the dual fuel engine from the forced evaporator;
A sub vaporized gas supply line branching from the vaporized gas supply line before the main compression unit and supplying vaporized gas generated from the storage tank to the gas combustion unit;
A ship's low pressure fuel supply device comprising a sub compression unit installed on the sub vaporized gas supply line, compressing the vaporized gas to a pressure required by the gas combustion unit, and having a compressor relatively smaller than the main compression unit.
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