KR102189758B1 - Fuel gas supplying system - Google Patents

Abstract

A fuel gas supply system is started. The fuel gas supply system according to an embodiment of the present invention includes a storage tank for receiving fuel gas composed of liquefied gas and evaporative gas, a liquefied gas supply line for supplying liquefied gas from the storage tank to an engine, and boil-off gas from the storage tank to an engine. It may be provided, including a methane number control unit that adjusts the methane number of the fuel gas so as to supply the fuel gas according to the condition methane number of the fuel gas required by the supplied boil-off gas supply line and the engine.

Description

Fuel gas supply system {FUEL GAS SUPPLYING SYSTEM}

The present invention relates to a fuel gas supply system, and more particularly, to a fuel gas supply system for ships capable of effectively supplying fuel gas in accordance with a methane number of fuel gas required by a ship's engine.

As the regulations of the International Maritime Organization (IMO) on the emission of greenhouse gases and various air pollutants are strengthened, the shipbuilding and shipping industries use natural gas, a clean energy source, instead of the existing fuel oil and diesel oil. It is increasingly used as.

Natural gas, which is widely used and considered an important resource among fuel gases, has methane as its main component, and in general, natural gas is cooled to about -162 degrees Celsius for ease of storage and transportation to reduce its volume to 1 The phase is changed to Liquefied Natural Gas, a colorless transparent cryogenic liquid reduced to /600, and is being managed and operated.

The liquefied natural gas is stored and transported by being accommodated in a storage tank that is insulated and installed on the hull, and the engine of the ship is driven by being supplied with liquefied natural gas or boiled off gas as fuel gas. Here, the evaporation gas includes natural evaporation gas generated by natural evaporation of liquefied natural gas contained in the storage tank and forced evaporation gas generated by forcibly evaporating. 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, nowadays, different fuel engines such as DFDE engines are widely used for propulsion of ships or power generation of ships, and in particular, X-DF engines capable of combustion with medium pressure fuel gas have been developed and used.

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

On the other hand, methane has a boiling point of -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 natural evaporation gas naturally vaporized inside the storage tank has a high methane number, and in Laden Voyage where the storage tank is filled with liquefied natural gas, the amount of natural evaporation gas is large, so the appropriate methane number required by the engine. Can easily fit.

However, since the amount of natural evaporation gas is drastically reduced during ballast voyages where a lot of liquefied natural gas is not received in the storage tank, such as after unloading the liquefied natural gas, there is a problem that it is difficult to meet the appropriate methane value required by the engine. Accordingly, there is a need for a way to supply the methane number of fuel gas supplied to the engine to the level required by the engine even during air sailing.

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

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

An embodiment of the present invention is to provide a fuel gas supply system capable of effectively treating or using boil-off gas.

An embodiment of the present invention is to provide a fuel gas supply system capable of promoting efficient operation with a simple structure.

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

According to an aspect of the present invention, a storage tank for receiving fuel gas consisting of liquefied gas and evaporative gas, a liquefied gas supply line for supplying the liquefied gas of the storage tank to the engine, and supplying boil-off gas of the storage tank to the engine It may be provided, including a methane number control unit for adjusting the methane number of the fuel gas so as to supply the fuel gas according to the condition methane number of the fuel gas required by the engine and the boil-off gas supply line.

The methane number control unit is provided to be branched from the boil-off gas supply line and is connected to the liquefied gas supply line, a re-liquefaction device for liquefying the boil-off gas supplied to the methane number control line, and storing the liquefied boil-off gas. It may be provided including a buffer tank.

The methane number control unit may further include a supply control device for adjusting the supply amount of the liquefied boil-off gas in the buffer tank to the liquefied gas supply line.

The supply control device may include an opening/closing valve provided at an outlet of the buffer tank and a gas analyzer for analyzing the methane number of fuel gas supplied to the engine.

It may be provided, further comprising a control unit for controlling the operation of the on-off valve using the methane number analyzed by the gas analyzer.

The methane number control unit may be provided including a heat exchanger for mutually heat exchange between the boil-off gas passing through the methane number control line and the liquefied natural gas passing through the liquefied gas supply line.

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

The fuel gas supply system according to an exemplary embodiment of the present invention has an effect of improving engine efficiency and minimizing loads applied to the engine, such as engine knocking and piston wear, thereby improving the durability and life of the engine.

The fuel gas supply system according to an embodiment of the present invention has an effect of effectively treating or using boil-off gas generated in a storage tank containing liquefied natural gas.

The fuel gas supply system according to the embodiment of the present invention has a simple structure and has an effect of promoting efficient operation.

1 is a conceptual diagram showing a fuel gas supply system according to an embodiment of the present invention.
2 is a conceptual diagram showing a fuel gas supply system according to a modified 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 exemplary embodiments presented here, but may be embodied in other forms. In the drawings, in order to clarify the present invention, portions not related to the description may be omitted, and sizes of components may be slightly exaggerated to aid understanding.

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

Referring to FIG. 1, a fuel gas supply system 100 according to an embodiment of the present invention includes a storage tank 110 and a liquefied gas supply line 120 for supplying the liquefied natural gas of the storage tank 110 to the engine 10. ), the boil-off gas supply line 130 for supplying the boil-off gas of the storage tank 110 to the engine 10, and a methane number control unit for adjusting the methane number of the fuel gas supplied to the engine 10.

The storage tank 110 is provided to receive or store liquefied natural gas. The storage tank 110 may be provided with an insulated membrane-type cargo hold so as to minimize vaporization of liquefied natural gas due to external heat intrusion. The storage tank 110 stably stores liquefied natural gas and evaporative gas until it reaches the destination and unloads by receiving or storing liquefied natural gas from the production site of natural gas, but as described below, the engine or ship for propulsion of 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 insulated and installed, but since it is practically difficult to completely block the invasion of heat from the outside, there is an evaporation gas generated by the natural gas evaporation inside the storage tank 110. do. Since such boil-off gas raises the internal pressure of the storage tank 110, there is a risk of deformation and explosion of the storage tank 110, and thus there is a need to remove the boil-off gas from the storage tank 110. Accordingly, the boil-off gas generated inside the storage tank 110 can be used as a fuel gas of the engine 10 by the boil-off gas supply line 130 as in the embodiment of the present invention, and although not shown in the drawing, the storage tank The boil-off gas may be processed or consumed by supplying it to a vent mast (not shown) or a Gas Combustion Unit (GCU, not shown) provided on the upper part of 110.

The engine 10 may receive fuel gas such as liquefied natural gas and boil-off gas accommodated in the storage tank 110 to generate propulsion of a ship or generate power for power generation such as internal facilities of the ship. For example, the engine 10 may be a DFDE engine capable of generating output with low pressure fuel gas, or an X-DF engine capable of generating output with medium pressure fuel gas, but is not limited thereto, If the engine is affected by the methane number of 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 in accordance with the condition methane number required by the engine 10. Natural gas is mainly composed of methane, and in addition to methane, natural gas contains ethane, propane, butane, etc., but it is necessary to supply fuel gas in accordance with the condition required by the engine 10 to meet the methane number. ), it is possible to prevent the engine efficiency from being deteriorated and the engine piston from being worn, and the engine 10 can exhibit a normal output.

The liquefied gas supply line 120 is provided to supply the liquefied natural gas received 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 is connected to the engine 10 by joining the boil-off gas supply line 130 to be described later. 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. In contrast, instead of the delivery pump 123, a pressure build-up unit (PBU) is installed in the storage tank 110 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.

On the liquefied gas supply line 120, liquefied natural gas and re-liquefied so that the liquefied natural gas and the re-liquefied boil-off gas supplied through the methane gas control line 140 to be described later can be processed according to the conditions required by the engine 10. A pressure pump 121 for pressurizing the evaporated gas and a vaporizer 122 for vaporizing the pressurized fuel gas may be provided.

The boil-off gas supply line 130 is provided to supply the boil-off gas generated in the storage tank 110 to the engine 10 as fuel gas. The boil-off gas supply line 130 is provided with one end connected to the inside of the storage tank 110, and the other end is connected to the engine 10 by joining the liquefied gas supply line 120. One end of the boil-off gas supply line 130 may be disposed above the storage tank 110, and may include a compression unit 131 so that the boil-off gas can be processed according to the conditions required by the engine 10. have.

The compression unit 131 may include one or more compressors 131a for compressing the boil-off gas and one or more coolers 131b for cooling the heated boil-off gas while being compressed. In FIGS. 1 and 2, a multi-stage compressor including two compressors 131a and two coolers 131b is illustrated, but the number of compressors 131a and coolers 131b may be variously changed as necessary. I can.

Meanwhile, the boiling point of methane, the main component of liquefied natural gas, is -161.5 degrees Celsius, which is lower than that of ethane (boiling point -89 degrees Celsius) and propane (boiling point -45 degrees Celsius), which are other components of natural gas. Accordingly, the evaporation gas in which the liquefied natural gas is naturally evaporated in the storage tank 110 has a relatively high content of methane, and thus, the evaporation gas has a high methane number. Accordingly, in the case of laden voyage in which the storage tank 110 is filled with liquefied natural gas, the amount of naturally occurring boil-off gas is increased, so that the appropriate methane number required by the engine 10 can be easily adjusted.

However, on the contrary, in the case of ballast voyage after consuming all of the liquefied natural gas inside the storage tank 110 or after unloading, the amount of liquefied natural gas stored inside the storage tank 110 is small, so evaporation that occurs naturally. Since the amount of gas generated is also reduced, the methane number of the fuel gas decreases, and thus it is difficult to meet the appropriate methane number required by the engine 10.

In addition to the meaning due to the capacity of liquefied natural gas in the storage tank 110, respectively, the full sailing and airborne sailing described in this embodiment are supplied to the engine 10 by mixing liquefied natural gas and boil-off gas without a separate device. Even if the methane number of fuel gas can be easily adjusted to the condition methane number required by the engine 10, and when liquefied natural gas and boil-off gas are supplied to the engine 10 without a separate device, the methane number of the fuel gas is It should be viewed as a comprehensive concept that includes each case that is lower than the methane number required by ).

The methane number control unit is re-liquefied by a methane number control line 140 provided by branching to the boil-off gas supply line, a re-liquefaction device 141 for re-liquefying the boil-off gas supplied to the methane number control line 140, and a re-liquefaction device 141 It may include a buffer tank 142 for storing the evaporated gas, and a supply control device 143 for controlling the supply of the reliquefied boil-off gas stored in the buffer tank 142 to the liquefied gas supply line 120.

The methanol control line 140 may be provided to connect between the front end of the compression unit 131 of the boil-off gas supply line 130 and the front end of the pressurization pump 121 of the liquefied gas supply line 120. The inlet side of the methane number control line 140 is provided to be branched from the boil-off gas supply line 130, and a part of the boil-off gas passing through the boil-off gas supply line 130 may be supplied to a reliquefaction device 141 to be described later.

The reliquefaction device 141 is provided on the methane number control line 140 to reliquefy the boil-off gas supplied to the methane number control line 140. The reliquefaction device 141 may be formed of a cooling device such as a cooler or a refrigerant line using a refrigerant. In addition, it may be formed of a heat exchanger 241 that exchanges heat with the liquefied natural gas supplied from the storage tank 110. This will be described later with reference to FIG. 2.

The buffer tank 142 may be provided at the rear end of the reliquefaction device 141 on the methane gas control line 140 to store the reliquefied boil-off gas through the reliquefaction device 141. The reliquefaction device 141 and the buffer tank 142 reliquefy and store the relatively high methane number of boil-off gas generated during full sailing, and liquefy the re-liquefied boil-off gas when the methane number of the fuel gas is low during the voyage. It is supplied to the gas supply line 120 to increase the methane number of the fuel gas.

The supply control device 143 may include an on-off valve 143a provided in the methane number control line 140 and a gas analyzer 143b for analyzing the methane number of liquefied natural gas passing through the liquefied gas supply line 120. have. The supply control device 143 is a methane number control line 140 and a liquefied gas supply line 120 to control the supply amount of the re-liquefied boil-off gas supplied to the liquefied gas supply line 120 through the methane number control line 140. It can be provided at the point of confluence.

The opening/closing valve 143a is provided in the methane gas control line 140 on the outlet side of the buffer tank 142, and controls the supply amount of the reliquefied boil-off gas that is sent from the buffer tank 142 and supplied to the liquefied gas supply line 120. I can. The opening/closing valve 143a may be manually opened/closed by an operator or automatically opened/closed by a controller (not shown) to be described later to control the flow rate of the reliquefied boil-off gas supplied to the liquefied gas supply line 120 .

Specifically, during full sailing, the methane number of the fuel gas supplied to the engine 10 can be easily adjusted to the condition methane number required by the engine 10 as the amount of boil-off gas generated in the storage tank 110 increases. In addition to the boil-off gas supplied to (10), a storage space is generated. Therefore, during full sailing, the opening/closing valve (143a) is closed, and the boil-off gas having a relatively high methane number is reliquefied using the reliquefaction device 141, and then stored in the buffer tank 142. In addition, during airborne navigation, by opening the on-off valve (143a) to supply the reliquefied boil-off gas having a relatively high methane number stored in the buffer tank 142 to the liquefied gas supply line 120, which is supplied to the engine 10. The methane number of fuel gas can be adjusted.

The gas analyzer 143b is provided to analyze the methane number of liquefied natural gas supplied to the engine 10. The gas analyzer 143b may be configured as a methane detector to analyze the methane content of the liquefied natural gas. In FIGS. 1 and 2, the gas analyzer 143b is shown to be installed at the point where the liquefied gas supply line and the methane gas control line 140 merge, but the liquefied gas immediately before being supplied to the engine 10 for accurate analysis It may be provided on the supply line. The gas analyzer 143b may analyze the methane number of the fuel gas at regular intervals or continuously, and transmit the methane number data to the occupant or a control unit (not shown) of the ship.

The control unit (not shown) may be provided to control the opening/closing operation of the on/off valve 143a. The controller may compare the methane number data received from the gas analyzer 143b with the previously input condition methane number and then control the opening and closing operation of the on-off valve 143a. In addition, the control unit may be composed of a system that comprehensively controls the operation of other components such as the compression unit 131 or the pressure pump 121 described above, and the supply amount and methane number of fuel gas supplied to the engine 10 by the automation system. It can be arranged to comprehensively analyze and control.

Hereinafter, a fuel gas supply system according to a modified embodiment of the present invention will be described.

2 is a conceptual diagram showing a fuel gas supply system 200 according to a modified embodiment of the present invention. Referring to FIG. 2, the reliquefaction device 141 included in the methane number control unit is formed of a heat exchanger 241. I can.

The heat exchanger 241 exchanges the boil-off gas passing through the methane number control line 140 and the liquefied natural gas passing through the liquefied gas supply line to re-liquefy the boil-off gas supplied to the methane number control line 140. Since the boil-off gas 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 cost of building facilities is reduced, thus promoting operational efficiency. You will be able to. In addition, although not shown in the drawings, a separate spray nozzle or a cooling device (not shown) may be additionally provided inside the buffer tank 142 in order to suppress evaporation gas generated inside the buffer tank 142.

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

During full sailing, the storage tank 110 contains a large amount of liquefied natural gas, and thus the amount of boil-off gas is large. Accordingly, the methane number of the fuel gas supplied to the engine 10 by the boil-off gas having a relatively high methane number can be easily adjusted to the condition methane number required by the engine 10, and in addition to the boil-off gas supplied to the engine 10 There is a spare amount that can be stored. At this time, the opening/closing valve 143a of the methane gas control line 140 is closed, and a part of the boil-off gas passing through the boil-off gas supply line 120 is supplied to the methane gas control line 140 to re-liquefy or heat exchange. Reliquefied through the group 241, and the reliquefied boil-off gas is stored in the buffer tank 142.

In the case of aerial sailing in which the capacity of the liquefied natural gas in the storage tank 110 is reduced by unloading or consuming all of the liquefied natural gas inside the storage tank 110, the amount of boil-off gas is also reduced. Accordingly, the methane number of the fuel gas supplied to the engine 10 is lower than the methane value of the condition required by the engine 10. In this case, the opening/closing valve 143a is opened to supply the re-liquefied boil-off gas of relatively high methane value stored in the buffer tank 142 to the liquefied gas supply line 120 and mix it with the liquefied natural gas, and the engine 10 To supply. Since the re-liquefied boil-off gas has a relatively higher methane value compared to the liquefied natural gas, the re-liquefied boil-off gas and the liquefied natural gas are mixed and supplied to the engine 10 to increase the methane value of the fuel gas. The gas analyzer 143b analyzes the methane number of fuel gas, particularly liquefied natural gas supplied to the engine 10, and transmits the analyzed methane number data to the occupant or the control unit of the ship. The occupant or the control unit of the ship compares the received methane number data with the pre-input condition methane number required by the engine 10 to control the opening and closing operation of the on/off valve 143a to control the methane number of fuel gas.

The fuel gas supply systems 100 and 200 according to an embodiment of the present invention having such a configuration have an effect of effectively adjusting the methane number of the fuel gas according to the condition methane number required by the engine 10.

Further, it is possible to improve the efficiency of the engine 10 and minimize the load applied to the engine 10 such as knocking of the engine 10 and abrasion of the piston, thereby improving the durability and life of the engine 10, and with a simple structure. Since the methane number of fuel gas can be easily controlled, it has the effect of reducing the cost for facility construction and enabling efficient facility operation.

In the above embodiments, as an example for aiding understanding of the present invention, the liquefied natural gas and the evaporative gas generated therefrom have been described, but are not limited thereto, and even when liquefied ethane, etc. Must be understood.

The present invention has been described with reference to an embodiment shown in the accompanying drawings, but this is only exemplary, and those of ordinary skill in the art can recognize that various modifications and other equivalent embodiments are possible therefrom. You can understand. Therefore, the true scope of the present invention should be determined only by the appended claims.

10: engine 100, 200: fuel gas supply system
110: storage tank 120: liquefied gas supply line
121: pressure pump 122: carburetor
130: boil-off gas supply line 131: compression unit
140: methane number control line 141: reliquefaction device
142: buffer tank 143: supply control device
143a: on-off valve 143b: gas analyzer
241: heat exchanger

Claims (6)

A storage tank for accommodating fuel gas consisting of liquefied gas and boil-off gas;
A liquefied gas supply line for supplying the liquefied gas from the storage tank to the engine;
A boil-off gas supply line for supplying boil-off gas from the storage tank to the engine; And
A methane number control unit for adjusting the methane number of the fuel gas so as to supply the fuel gas according to the methane number of the fuel gas condition required by the engine,
The methane number control unit
A methane number control line provided to be branched from the boil-off gas supply line and connected to the liquefied gas supply line, a re-liquefaction device for liquefying the boil-off gas supplied to the methane number control line, and relatively liquefied through the re-liquefaction device A buffer tank for storing the boil-off gas having a high methane number, and a supply control device for controlling a supply amount of the re-liquefied boil-off gas having a relatively high methane number stored in the buffer tank to the liquefied gas supply line,
The supply control device
An on/off valve provided at an outlet side of the buffer tank on the methane number control line, and a gas analyzer for analyzing the methane number of fuel gas supplied to the engine, wherein the on/off valve
A fuel gas supply system whose operation is controlled according to the methane number data analyzed from the gas analyzer. The method of claim 1,
The reliquefaction device
A fuel gas supply system including a heat exchanger for mutually exchanging the boil-off gas passing through the methane gas control line and the liquefied natural gas passing through the liquefied gas supply line.
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