KR102260379B1 - Fuel gas supplying system in ships - Google Patents

Abstract

A fuel gas supply system for a ship is disclosed. A fuel gas supply system for a ship according to an embodiment of the present invention separates the methane component contained in the storage tank for accommodating the liquefied gas, the liquefied gas supply line for supplying the liquefied gas of the storage tank to the engine, and the liquefied gas supplied to the engine. It may be provided including a methane number control unit.

Description

Ship's fuel gas supply system {FUEL GAS SUPPLYING SYSTEM IN SHIPS}

The present invention relates to a fuel gas supply system for a ship, and more particularly, to a fuel gas supply system for a ship capable of effectively controlling a methane number of fuel gas supplied to an engine.

As the International Maritime Organization (IMO)'s regulations on the emission of greenhouse gases and various air pollutants are strengthened, the shipbuilding and shipping industry replaces the existing fuels such as heavy oil and diesel oil, and uses natural gas, a clean energy source, as a fuel gas for ships. is being used more and more.

Natural gas, which is widely used and considered as an important resource among fuel gas, has methane as its main component, and its volume is reduced by 1 by cooling it to about -162 degrees Celsius for ease of storage and transportation. It is managed and operated by changing the phase to liquefied natural gas, a colorless and transparent cryogenic liquid reduced to /600.

Such liquefied natural gas is stored and transported by being accommodated in a storage tank that is installed after being insulated on the hull, and the engine of the ship is driven by receiving liquefied natural gas or boil-off gas as fuel gas. Here, the boil-off gas includes natural evaporation gas generated by natural evaporation of liquefied natural gas accommodated in the storage tank, and forced evaporation gas generated by forcibly vaporizing. Liquefied natural gas or boil-off gas is supplied according to the conditions required by the engine through processing such as compression and vaporization.

Meanwhile, heterogeneous fuel engines such as DFDE engines are widely used today for propulsion of ships or power generation of ships. In particular, recently, an X-DF engine capable of combustion with medium pressure fuel gas has been developed and used.

In addition to methane, natural gas includes ethane, propane, butane, etc., and the composition varies depending on the production area. In order to supply liquefied natural gas or vaporized BOG as fuel gas to X-DF engines, etc. It must be supplied according to the conditions of the methane number required by the engine. If the fuel gas supplied to the engine is lower than the appropriate methane number, explosion and combustion occur before the piston of the engine reaches top dead center, causing problems such as abrasion of the engine piston, deterioration of engine efficiency, and knocking. This is because the engine can produce normal output only when fuel gas is supplied according to the proper methane number required by the engine.

Meanwhile, the boiling point of methane is -161.5 degrees Celsius, which is lower than other components of natural gas such as ethane (boiling point -89 degrees Celsius) and propane (boiling point -45 degrees Celsius). Accordingly, the evaporative gas that is naturally vaporized inside the storage tank has a high methane number, and the amount of natural evaporative gas generated during a laden voyage with the storage tank full of liquefied natural gas is large, so the appropriate methane number required by the engine can be easily matched.

However, during ballast voyage, where the storage tank does not contain much liquefied natural gas, such as after unloading liquefied natural gas, the amount of natural evaporative gas is greatly reduced, so the liquefied natural gas is vaporized and used as fuel gas. In this case, since components such as ethane and propane included in the liquefied natural gas are vaporized together with methane and supplied as fuel gas, it is difficult to meet the proper methane number required by the engine.

Therefore, there is a need for a method to prevent a decrease in the methane number of the fuel gas supplied to the engine and effectively maintain the methane number of the fuel gas even during ballistic sailing.

Republic of Korea Patent Publication No. 10-2010-0035223 (published on 04. 05. 2010)

An embodiment of the present invention is to provide a fuel gas supply system for a ship that can effectively suppress a decrease in the methane number of the fuel gas supplied to the engine.

An embodiment of the present invention is to provide a fuel gas supply system for a ship capable of effectively maintaining the methane number of the fuel gas supplied to the engine.

An embodiment of the present invention is to provide a fuel gas supply system for a ship that can promote efficient operation with a simple structure.

An embodiment of the present invention is to improve the efficiency of the engine and to provide a fuel gas supply system for a ship capable of minimizing the load applied to the engine.

According to one aspect of the present invention, a storage tank for accommodating liquefied gas, a liquefied gas supply line for supplying the liquefied gas of the storage tank to the engine, and a methane number control unit for separating the methane component contained in the liquefied gas supplied to the engine included may be provided.

The methane number control unit may include a membrane filter that passes methane contained in the liquefied gas and filters out components other than methane, and a recovery line that recovers the components filtered by the membrane filter to the storage tank.

The methane number control unit may be provided by further comprising a reliquefaction device provided in the recovery line to reliquefy the components filtered by the membrane filter.

The liquefied gas supply line may include a pressurization pump for pressurizing the liquefied gas and a vaporizer for vaporizing the liquefied gas pressurized by the pressurization pump, and the membrane filter may be provided at a rear end of the vaporizer.

The re-liquefaction device may be provided as a heat exchanger for exchanging heat with components other than methane recovered through the recovery line and the liquefied gas passing through the liquefied gas supply line.

The fuel gas supply system of a ship according to an embodiment of the present invention has the effect of maintaining and supplying the methane number of the fuel gas supplied to the engine at an appropriate level required by the engine.

The fuel gas supply system of a ship according to an embodiment of the present invention has the effect of preventing a decrease in the methane number of the fuel gas supplied to the engine during the ballistic voyage.

The fuel gas supply system of a ship according to an embodiment of the present invention has the effect of improving the efficiency of the engine and minimizing the load applied to the engine, such as knocking of the engine and abrasion of the piston, thereby improving the durability and lifespan of the engine.

The fuel gas supply system of a ship according to an embodiment of the present invention has an effect that can promote efficient operation with a simple structure.

1 is a conceptual diagram illustrating a fuel gas supply system for a ship according to an embodiment of the present invention.
2 is a conceptual diagram illustrating a fuel gas supply system for a ship according to another embodiment of the present invention.
3 is a conceptual diagram illustrating a modified example of a fuel gas supply system for a ship according to another embodiment of the present invention.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. The following examples are presented in order to sufficiently convey the spirit of the present invention to those of ordinary skill in the art to which the present invention pertains. The present invention is not limited to the embodiments presented herein and may be embodied in other forms. The drawings may omit the illustration of parts irrelevant to the description in order to clarify the present invention, and may slightly exaggerate the size of the components to help understanding.

1 is a conceptual diagram illustrating a fuel gas supply system 100 for a ship according to an embodiment of the present invention.

Referring to FIG. 1 , a fuel gas supply system 100 for a ship according to an embodiment of the present invention is a storage tank 110 and a liquefied gas supply line for supplying the liquefied natural gas of the storage tank 110 to the engine 10 . 120 and a methane number control unit 130 for adjusting the methane number of the liquefied natural gas supplied to the engine 10 may be provided.

The storage tank 110 is provided to accommodate or store liquefied natural gas and boil-off gas. The storage tank 110 may be provided as a membrane-type cargo hold insulated to minimize vaporization of liquefied natural gas due to external heat intrusion. The storage tank 110 receives or stores liquefied natural gas from a natural gas production area, etc., and stably stores the liquefied natural gas and boil-off gas until it reaches the destination and is unloaded, but as will be described later, a propulsion engine of a ship or a ship. It may be provided to be used as fuel gas, such as an engine for power generation.

The storage tank 110 is generally installed with heat insulation, but it is practically difficult to completely block the intrusion of external heat, so natural evaporation gas generated by the natural vaporization of the liquefied natural gas is present in the storage tank 110 . will do Since the spontaneous evaporation gas raises the internal pressure of the storage tank 110 and poses a risk of deformation and explosion of the storage tank 110 , it is necessary to remove the natural evaporation gas from the storage tank 110 . Accordingly, the natural evaporation gas generated inside the storage tank 110 may be used as fuel gas of the engine 10 through a boil-off gas supply line (not shown) together with liquefied natural gas. In addition, although not shown in the drawings, a vent mast (not shown) or a gas combustion unit (GCU, not shown) may be provided in the storage tank 110 to process or consume excess BOG.

The engine 10 may receive fuel gas such as liquefied natural gas or boil-off gas contained in the storage tank 110 to generate propulsion force of the ship or to generate power for power generation such as internal facilities of the ship. As an example, the engine 10 may be a DFDE engine capable of generating output with fuel gas of low pressure or an X-DF engine capable of generating output with fuel gas of medium pressure, but is not limited thereto, If the engine is affected by the methane number of the fuel gas, it includes all cases of various engines.

When the fuel gas supplied to the engine 10 is natural gas, the methane number of the fuel gas must be supplied according to the methane number required by the engine 10 . The main component of natural gas is methane, and in addition to methane, it includes ethane, propane, butane, and the like. ), deterioration of engine efficiency, and abrasion of engine pistons can be prevented, and the engine can exhibit normal output.

The liquefied gas supply line 120 is provided to supply the liquefied natural gas accommodated or stored in the storage tank 110 as a fuel gas to the engine 10 . The liquefied gas supply line 120 is provided with one end connected to the inside of the storage tank 110 , and the other end connected with the engine 10 . One end of the liquefied gas supply line 120 may be disposed below the storage tank 110 , and a delivery pump 123 may be provided to supply the liquefied natural gas to the engine 10 side. Unlike this, a pressure build-up unit (PBU) is installed in the storage tank 110 instead of the delivery pump 123 to increase the internal pressure of the storage tank 110 to supply liquefied natural gas to the liquefied gas supply line 120 ) may be provided to supply.

On the liquefied gas supply line 120, a pressurization pump 121 for pressurizing the liquefied natural gas so that the liquefied natural gas can be processed according to the conditions required by the engine 10, and a vaporizer 122 for vaporizing the pressurized liquefied natural gas The methane number of the liquefied natural gas supplied to the engine 10 may be adjusted by providing a methane number adjusting unit 130 to be described later.

Meanwhile, the boiling point of methane, the main component of liquefied natural gas, is -161.5 degrees Celsius, which is lower than other components of natural gas such as ethane (boiling point -89 degrees Celsius) and propane (boiling point -45 degrees Celsius). Therefore, the natural evaporation gas generated by the natural vaporization of the liquefied natural gas in the storage tank 110 has a relatively large content of methane, and the boil-off gas has a high methane number. Conversely, liquefied natural gas loses methane by evaporative gas over time, and thus has a relatively low methane number compared to natural evaporative gas.

Accordingly, when the storage tank 110 is full of liquefied natural gas during a laden voyage, the amount of naturally occurring evaporative gas is large, so the evaporative gas is forced into the engine 10 together with the forcibly vaporized liquefied natural gas. ), it is possible to easily meet the condition methane number required by the engine 10 . Conversely, in the case of ballast voyage after consuming all of the liquefied natural gas in the storage tank 110 or after unloading, the amount of liquefied natural gas stored in the storage tank 110 is small, so naturally occurring evaporative gas Since the generation amount of is also reduced, there is a problem in that it is difficult to match the methane number of the fuel gas vaporized with the liquefied natural gas to the appropriate methane number required by the engine 10 .

In addition to the meaning due to the capacity of the liquefied natural gas in the storage tank 110, the full voyage and the ballistic voyage described in this embodiment each operate the liquefied natural gas and boil-off gas of the storage tank 110 without a separate device to the engine ( Even if supplied to 10), the methane number of the fuel gas can be easily adjusted to the methane number required by the engine 10, and the liquefied natural gas and boil-off gas of the storage tank 110 are supplied to the engine 10 without a separate device. In the case of supply, the methane number of the fuel gas should be viewed as a comprehensive concept including a state in which it is difficult to meet the condition methane number required by the engine 10 .

The methane number control unit 130 includes a membrane filter 131 for filtering out methane components and components other than methane, a recovery line 132 for recovering components other than methane filtered by the membrane filter 131 to the storage tank 110 , a membrane filter Includes a reliquefaction device 133 provided to reliquefy components other than methane filtered by 131 and recover it to the storage tank 110 and a GCU 134 that consumes components other than methane filtered by the membrane filter 131 can be provided.

The membrane filter 131 may be provided at the rear end of the vaporizer 122 of the liquefied gas supply line 120 . Methane has smaller molecules than ethane and propane. Using this point, the membrane filter 131 is provided with a polymer thin film so that methane of the liquefied natural gas can pass through and components other than methane such as ethane and propane can be filtered out. The size of the micropores formed in the polymer thin film is larger than the molecular size of methane and smaller than the molecular size of ethane or propane, so that the methane passes through the fuel gas supplied to the engine 10, and other methane such as ethane and propane The component may be filtered to increase the methane number of the fuel gas supplied to the engine 10 .

The recovery line 132 connects the membrane filter 131 and the storage tank 110 , and is provided to recover components other than methane filtered by the membrane filter 131 to the storage tank 110 . The recovery line 132 returns the components other than methane, such as ethane and propane, filtered by the membrane filter 131 to the inside of the storage tank 110 .

2 is a conceptual diagram illustrating a fuel gas supply system 100 for a ship according to another embodiment of the present invention.

Referring to FIG. 2 , the reliquefaction device 133 is provided on the recovery line 132 to reliquefy components other than methane such as ethane and propane filtered by the membrane filter 131 to be recovered to the storage tank 110 . do. When the components other than methane filtered by the membrane filter 131 are recovered to the storage tank 110 as they are, the liquefied natural gas is vaporized through the pressurization pump 121 and the vaporizer 122 in the state of the forced evaporation gas in the storage tank 110 ), there is a risk of excessively increasing the internal pressure of the storage tank 110 . Therefore, by re-liquefying components other than methane by the re-liquefaction device 133 and recovering it to the storage tank 110, the internal pressure of the storage tank 110 is prevented from excessively rising, and the Temperature rise can be prevented.

The re-liquefaction device 133 may be formed of a cooling device such as a cooler or a refrigerant line using a refrigerant, or alternatively, a heat exchanger 135 that exchanges heat with the liquefied natural gas supplied from the storage tank 110 . This will be described later with reference to FIG. 3 .

A gas combustion unit (GCU) 134 may be provided on the recovery line 132 to consume components other than methane such as ethane and propane filtered by the membrane filter 131 . When there are many components other than methane filtered by the membrane filter 131 , there is a risk that the internal pressure of the storage tank 110 may increase excessively, and a load may be applied to the reliquefaction apparatus 133 described above. Therefore, since the GCU 134 is branched to the recovery line 132 and provided, when the component other than methane exceeds a certain amount or more, the component other than methane can be supplied to the GCU 134 for consumption. Also, although not shown in the drawings, an on/off valve (not shown) may be additionally provided at the front end of the GCU 134 to control components other than methane supplied to the GCU 134 .

3 is a conceptual diagram illustrating a modified example of the fuel gas supply system 100 of a ship according to another embodiment of the present invention. Referring to FIG. 3 , the reliquefaction device 133 provided in the recovery line 132 is heat exchanged. It may consist of group 135 .

The heat exchanger 135 exchanges heat between components other than methane passing through the recovery line 132 and liquefied natural gas passing through the liquefied gas supply line 120 , and is supplied to the storage tank 110 through the recovery line 132 . Reliquefy components other than methane. Since components other than methane can be easily re-liquefied through heat exchange with the liquefied gas supply line 120 without a cooling device such as a separate cooler or a refrigerant line, the configuration is simplified and the facility construction cost is reduced, thereby promoting operational efficiency. be able to do In addition, although not shown in the drawings, a pressure reducing valve (not shown) may be additionally provided in the recovery line 132 to prevent the internal pressure of the storage tank 110 from excessively increasing.

Hereinafter, the operation of the fuel gas supply system 100 of the ship according to an embodiment of the present invention will be described.

The evaporative gas generated by naturally vaporizing in the storage tank 110 contains a large amount of methane component due to the difference in boiling point. Conversely, liquefied natural gas has a relatively low methane content compared to natural evaporation gas, resulting in a lower methane number. Therefore, when it is desired to supply the liquefied natural gas to the engine 10 as fuel gas, the liquefied natural gas is supplied along the liquefied gas supply line 120 , and the fuel gas vaporized through the pressurization pump 121 and the vaporizer 122 . is supplied to the membrane filter 131 of the methane number control unit 130 .

The membrane filter 131 passes methane through the polymer thin film and filters out components other than methane such as ethane and propane. Accordingly, the fuel gas passing through the membrane filter 131 has a high methane number and is supplied to the engine 10 , and components other than methane filtered by the membrane filter 131 are returned to the storage tank 110 by the recovery line 132 . is recovered

Components other than methane filtered by the membrane filter 131 are directly recovered to the storage tank 110, or re-liquefied through the re-liquefaction device 133 to prevent excessive increases in internal pressure and internal temperature of the storage tank 110. After that, it may be recovered to the storage tank 110 . The re-liquefaction device 133 may include a heat exchanger 135 that performs heat exchange with the liquefied natural gas supplied along the liquefied gas supply line 120 . When the amount of components other than methane filtered by the membrane filter 131 with only the recovery line 132 is excessively large or to prevent mismatch of fuel gas components, components other than methane are supplied to the GCU 134 for consumption.

The fuel gas supply system 100 for a ship according to an embodiment of the present invention having such a configuration can maintain and supply the methane number of the fuel gas supplied to the engine at an appropriate level required by the engine, and efficiently consume the fuel gas. have an achievable effect.

Furthermore, it is possible to improve the efficiency of the engine and minimize the load applied to the engine such as knocking of the engine and wear of the piston, thereby improving the durability and lifespan of the engine. It has the effect of reducing costs and enabling efficient facility operation.

In the above embodiment, as an example for helping the understanding of the present invention, liquefied natural gas and boil-off gas generated therefrom have been applied and described, but the present invention is not limited thereto, and even when liquefied ethane is applied, the same technical concept is the same. should be understood

Although the present invention has been described with reference to one embodiment shown in the accompanying drawings, this is merely exemplary, and those skilled in the art will appreciate that various modifications and equivalent other embodiments are possible therefrom. You will understand. Accordingly, the true scope of the invention should be defined only by the appended claims.

100: fuel gas supply system 110: storage tank
120: liquefied gas supply line 121: pressurized pump
122: vaporizer 130: methane number control unit
131: membrane filter 132: recovery line
133: reliquefaction unit 134: GCU
135: heat exchanger

Claims (5)

a storage tank for accommodating liquefied gas;
a liquefied gas supply line for supplying the liquefied gas of the storage tank to the engine; and
And a methane number control unit for separating the methane component contained in the liquefied gas supplied to the engine,
The methane number control unit
A membrane filter that passes methane contained in the liquefied gas and filters out components other than methane;
a recovery line connecting the membrane filter and the storage tank, and recovering components other than methane filtered by the membrane filter to the storage tank;
A reliquefaction device for reliquefying components other than methane filtered by the membrane filter,
The reliquefaction device is
A fuel gas supply system for a ship comprising a heat exchanger provided between the liquefied gas supply line and the recovery line to exchange heat between components other than methane recovered through the recovery line and the liquefied gas introduced into the liquefied gas supply line. delete According to claim 1,
The liquefied gas supply line is
A pressurizing pump for pressurizing liquefied gas;
It includes a vaporizer for vaporizing the liquefied gas pressurized by the pressurization pump,
The membrane filter is a fuel gas supply system of a ship provided at the rear end of the carburetor.


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