KR101370065B1 - System And Method For Fuel Gas Supply - Google Patents

Abstract

Low pressure gas fuel supply line connected from the LNG storage tank to the low pressure gas engine, the vaporizer and heater installed in the low pressure gas fuel supply line, the gas supply line connected to the low pressure gas fuel supply line in the gas supply source, the pressure control means is installed, the pressure control A fuel supply line for branching connected to the low pressure gas fuel supply line in front of the low pressure vaporizer and branched in the middle of the oil supply line in front of the means, and a connection end of the fuel supply line and the low pressure gas fuel supply line, and the fuel supply line for oil supply And a first check valve installed at the low pressure gas fuel supply line between the low pressure gas fuel supply line and a connection end of the low pressure gas fuel supply line.

Description

System And Method For Fuel Gas Supply

The present application relates to a fuel gas supply, and more particularly, to a fuel gas supply system and a method for supplying fuel gas to a vessel using LNG as a fuel as well as an LNG carrier including a ship propulsion engine and a power generation engine. will be.

In general, a vessel carrying a liquefied natural gas (Liquefied Natural Gas, hereinafter referred to as 'LNG') is transported by liquefying natural gas in the cryogenic state of -163 ℃ at normal pressure. The liquefied gas in this cryogenic state, that is, LNG, is continuously generated by boil-off gas (BOG) as heat is supplied due to a temperature difference from the outside. Evaporative gas reliquefaction equipment is returned to storage tanks to reduce waste.

On the other hand, the high-pressure gas engine, for example, in the case of the ME-GI engine, a high-pressure natural gas as a fuel, it is necessary to supply a high pressure gas of about 150 ~ 250 bar.

Pressurizing the gas in pressurizing the same mass flow fluid requires significantly more power consumption than pressurizing the liquid, especially at high pressures of about 200 bar.

For this reason, the preceding invention related to the high pressure gas engine describes a method for pressurizing only liquid to pressurize the fuel to high pressure. However, fuel is stored at an extremely low temperature (about -160 ° C) due to the nature of LNG, and evaporation gas is continuously generated by heat inflow from the outside. If the evaporated gas is not taken out of the tank, the internal pressure of the storage tank may increase, which may damage the storage tank.

The fuel gas supply apparatus and method for a LNG carrier according to the prior art is Korean Patent Application No. 10-2008-0103550, which extracts LNG from an LNG storage tank, compresses it with a high pressure pump and vaporizes it to use a high pressure gas engine (ship propulsion engine). Meanwhile, a method of branching, expanding and supplying a part of the vaporized gas to a power generation engine is disclosed.

However, the fuel gas supplying method of the prior art increases the capacity of the high-pressure pump to increase both the initial investment cost and the operating cost, and there is a problem that the expanded gas generates droplets and affects the engine.

In addition, in general, the fuel gas supply device has a problem in that it is difficult to use gas fuel during bunkering because the filling line for bunkering LNG in the tank and the line for supplying fuel to the engine use the same line.

Even if you do not use gas fuel, you can run the generator with heavy fuel oil (HFO) or marine diesel oil (MDO) in oil mode, but you need to install a medium-sized boiler on your vessel to use these fuels. In consideration of the fact that ships mainly using gas fuel apply gas engines to comply with environmental regulations offshore, there is a need to convert the generator into a gas mode during bunkering.

In addition, when bunkering, a large amount of boil-off gas may be generated in the tank, and in general, the boil-off gas is returned to the onshore fuel supply base for processing, but if it is not processed at the fuel supply base, it can be burned or released to the atmosphere. It can only cause environmental pollution.

The present application is to solve the problems of the prior art as described above, a fuel supply system that can operate the engine for power generation using gas fuel even during fueling and at the same time can effectively treat the boil-off gas generated during oiling and To provide a method.

According to an aspect of the present invention, the fuel gas supply system is a low pressure gas fuel supply line connected to the low pressure gas engine from the LNG storage tank, a vaporizer and heater installed in the low pressure gas fuel supply line, connected to the low pressure gas fuel supply line in the gas source And a fuel supply line provided with a pressure regulating means, a fuel supply line branched in the middle of the oil filling line in front of the pressure regulating means and connected to the low pressure gas fuel supply line in front of the low pressure vaporizer, and the oil filling line and the low pressure. And a first check valve installed at the low pressure gas fuel supply line between a connection end of a gas fuel supply line and a connection end of the oil fuel supply line and the low pressure gas fuel supply line.

In addition, the fuel gas supply system may further include a flow control means installed in the fuel supply line for fueling.

In this embodiment, the pressure regulating means may be a pressure reducing valve.

In addition, the fuel gas supply system may further include an evaporation gas supply line connected to the low pressure gas fuel supply line at the rear end of the low pressure vaporizer from the LNG storage tank.

In addition, the fuel gas supply system is connected to the first ejector from the first branch line branched in the middle of the low pressure gas fuel supply line after the pressure regulating means, the first ejector installed in the first branch line, and the boil-off gas supply line. It may further comprise a boil-off gas recovery line.

In addition, the fuel gas supply system may further include a second check valve installed in the first branch line after the first ejector.

Further, the fuel gas supply system includes a second branch line branched in the middle of the low pressure gas fuel supply line after the low pressure vaporizer, a second ejector installed in the second branch line, and a main connected to the second ejector from the boil-off gas supply line. It may further comprise a useful boil-off gas supply line.

In addition, the fuel gas supply system may further include a third check valve installed in the second branch line after the second ejector.

In addition, the fuel gas supply system includes a third branch line branched in the middle of the oil supply line in front of the pressure regulating means, a third ejector installed in the third branch line, and recovery of boil-off gas connected to the third ejector from the boil-off gas supply line. And an auxiliary boil-off boil-off gas supply line branched in the middle of the third branch line on the outlet side of the third ejector and connected to the low-pressure gas fuel supply line in front of the low-pressure vaporizer.

In addition, the fuel gas supply system is branched in the low pressure gas fuel supply line is connected to the high-pressure gas engine, the high-pressure gas fuel supply line is installed, and the boil-off gas branched from the boil-off gas supply line connected to the recondenser It may further include a processing line.

According to another aspect of the present invention, the fuel gas supply method, when fuel gas is supplied to the LNG storage tank, the fuel gas of the gas source is supplied to the LNG storage tank via the oil supply line, at the same time the fuel gas of the gas source Vaporized and heated via the useful fuel supply line and the low pressure gas fuel supply line, the vaporizer and the heater is supplied to the low pressure gas engine.

Further, in the present embodiment, the boil-off gas generated in the LNG storage tank is mixed with the fuel gas vaporized through the vaporizer along the boil-off gas supply line connected to the low-pressure gas fuel supply line and passed through the heater to the low-pressure gas engine Can be supplied to.

In addition, in the present embodiment, when the pressure of the boil-off gas generated in the LNG storage tank is lower than the set pressure of the low-pressure gas engine, the boil-off gas is mixed with the fuel gas reduced in the oil supply line to the LNG storage tank Can be recovered.

In addition, in the present embodiment, when the pressure of the boil-off gas generated in the LNG storage tank is lower than the set pressure of the low-pressure gas engine, the boil-off gas along the boil-off gas supply line connected to the low-pressure gas fuel supply line The fuel gas vaporized through a vaporizer and the low pressure gas engine may be mixed in accordance with a set pressure of the low pressure gas engine and supplied to the low pressure gas engine through the heater.

Embodiment of the present invention has the effect of operating the low-pressure gas engine at the time of fueling the fuel gas in the LNG storage tank, at the same time by treating the fuel gas in accordance with the use conditions of the low-pressure gas engine.

In addition, in the embodiment of the present invention, when fuel gas is supplied to the LNG storage tank, the boil-off gas generated in the LNG storage tank may be used as the fuel gas for the low pressure gas engine.

In addition, the embodiment of the present invention, when fuel gas is supplied to the LNG storage tank, without the outgoing combustion of the evaporated gas generated in the LNG storage tank to the outside, by treating the fuel gas conditions to recover and recycle to the LNG storage tank It can work.

1 is a schematic diagram showing a fuel gas supply system according to an embodiment of the present invention.
2 is a view for explaining a fuel gas supply method according to the fuel gas supply system shown in FIG.
Figure 3 is a schematic diagram showing a fuel gas supply system according to another embodiment of the present invention.
4 is a view for explaining a fuel gas supply method and a boil-off gas processing method generated in the fuel gas supply system shown in FIG.
Figure 5 is a schematic diagram showing a fuel gas supply system according to another embodiment of the present invention.
6 is a view for explaining a fuel gas supply method and a boil-off gas processing method according to the fuel gas supply system shown in FIG.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. It is to be understood, however, that the appended drawings illustrate the present invention in order to more easily explain the present invention, and the scope of the present invention is not limited thereto. You will know.

Also, the terms used in the present application are used only to describe certain embodiments and are not intended to limit the present invention. Singular expressions include plural expressions unless the context clearly indicates otherwise. In this application, the terms "comprise" or "having" are intended to indicate that there is a feature, number, step, operation, component, part, or combination thereof described in the specification, and one or more other features. It is to be understood that the present invention does not exclude the possibility of the presence or the addition of numbers, steps, operations, components, components, or a combination thereof.

The meanings of the front end and the rear end used in the embodiment of the present invention are defined based on the supply path of the fuel gas. For example, the low pressure gas fuel supply line at the rear end of the low pressure vaporizer, the rear end of the low pressure vaporizer means the portion where the fuel gas flowed out of the low pressure vaporizer. Fig. 1 is a fuel gas according to an embodiment of the present invention. A schematic diagram illustrating a supply system.

As shown in FIG. 1, the fuel gas supply system 100 includes an LNG storage tank 1, a low pressure gas fuel supply line 8, a high pressure gas fuel supply line 10, an evaporation gas supply line 6, and a fuel supply source. (2), a fueling line (4), a fuel supply line (19) for oiling, and a first check valve (3).

The LNG storage tank 1 stores fuel gas maintained at about 5 to 7 bar at about -160 ° C.

The low pressure gas fuel supply line 8 is connected to the low pressure gas engine 30 starting from the lower portion of the LNG storage tank 1, and the low pressure gas fuel supply line 8 has a low pressure vaporizer 15 and a heater 16. Is installed. In this case, the low pressure gas engine 30 may include a DFDE engine used as an engine for power generation.

 The low pressure vaporizer 15 vaporizes LNG supplied from the LNG storage tank 1, and the heater 16 heats the vaporized low pressure fuel gas and supplies it to the low pressure gas engine 30.

The high pressure gas fuel supply line 10 is branched from the low pressure gas fuel supply line 8 and connected to the high pressure gas engine 20, and the high pressure gas fuel supply line 10 includes a recondenser 11 and a high pressure pump ( 12), the high pressure vaporizer 13 and the pressure damper 14 are provided. In this case, the high pressure gas engine 20 may include a ME-GI engine used as a propulsion engine.

The high pressure pump 12 compresses the low pressure fuel gas passed through the recondenser 11 to about 200 to 300 bar when the low pressure fuel gas supplied from the LNG storage tank 1 is supplied to the high pressure gas engine 20. The high pressure vaporizer 13 vaporizes the fuel gas compressed at high pressure and supplies the same to the high pressure gas engine 20. At this time, when the fuel gas is compressed and supplied at a high pressure, a pulsation phenomenon occurs in the fuel gas, thereby causing a problem that the pressure is not constant due to a change in the flow rate of the fuel gas.

The pressure damper 14 may be installed in the high pressure gas fuel supply line 10 at the front end of the high pressure gas engine 20 so as to maintain a constant pressure change according to the flow rate of the fuel gas.

The boil-off gas supply line 6 may be drawn out from the upper portion of the LNG storage tank 1 and connected to the low-pressure gas fuel supply line 8 at the rear end of the low-pressure vaporizer 15.

The boil-off gas supply line 6 receives the boil-off gas generated in the LNG storage tank 1 when the pressure in the LNG storage tank 1 rises higher than the set pressure during the operation of the LNG vessel. By supplying to the fuel cell, the boil-off gas can be used as a fuel gas without removing the combustion gas and burning it.

The boil-off gas treatment line 7 is branched from the boil-off gas supply line 6 and connected to the recondenser 11.

The recondenser 11 supplies the high-pressure gas engine 20 with the excess boil-off gas supplied through the boil-off gas treatment line 7 when the amount of boil-off gas generated in the LNG storage tank 1 is excessive. Recondensate for use as fuel.

The fuel supply source 2 includes an oil supply line 4 for supplying fuel gas to the LNG storage tank 1 and a fuel supply line 19 for supplying fuel gas to the low pressure gas engine 30.

The oil supply line 4 is connected to the low pressure gas fuel supply line 8, and a pressure regulating means 17 is installed in the oil supply line 4. The pressure regulating means 17 includes a pressure reducing valve, but any means can be used as long as it can reduce the pressure of the fuel gas.

The fuel supply line 19 for oiling is branched from the oil supply line 4 in front of the pressure regulating means 17 and connected to the low pressure gas fuel supply line 8 in front of the low pressure vaporizer 15. At this time, the fuel supply line 19 for fueling may be provided with a control means such as a flow control valve 18 to control the flow rate of the fuel gas.

The first check valve 3 is connected between the fuel supply line 4 and the low pressure gas fuel supply line 8, and the fuel supply line 19 and the low pressure gas fuel supply line 8. Is installed in the low pressure gas fuel supply line (8).

When the first check valve 3 supplies the fuel gas of the gas supply source 2 to the LNG storage tank 1 and the low pressure gas fuel supply line 8, the first check valve 3 is connected to the LNG storage tank 1 and the low pressure gas engine 30. Due to the set pressure difference, the fuel gas flowing in the low pressure gas fuel supply line 8 is prevented from flowing back to the LNG storage tank 1.

The second check valve 5 is installed in the high pressure gas fuel supply line 10 in front of the recondenser 11 so that the fuel gas of the main fuel source 2 passes through the low pressure gas fuel supply line 8. When supplied to 30, it is prevented from flowing to the high-pressure gas fuel supply line 10.

Looking at the fuel gas supply method according to the fuel gas supply system of the present embodiment as follows.

2 is a view for explaining a fuel gas supply method according to the fuel gas supply system shown in FIG.

Referring to the fuel gas supply method according to the fuel gas supply system 100 with reference to Figure 2, the fuel gas stored in the LNG storage tank (1) is discharged from the lower portion of the LNG storage tank (1) the low pressure gas fuel supply line (8) is supplied to the low pressure gas engine 30 via the low pressure vaporizer 15 and the heater 16-①, at the same time the fuel gas is branched from the low pressure gas fuel supply line (8) 10 is supplied to the high pressure gas engine 20 via the recondenser 11, the high pressure pump 12, and the high pressure vaporizer 13 installed in the high pressure gas fuel supply line 10.

On the other hand, at the time of refueling, the fuel gas stored in the refueling source 2 is supplied to the LNG storage tank 1 along the refueling line 4 via the low pressure gas fuel supply line 8-③. In this case, the low pressure gas fuel supply line 8 may be used as a fuel gas supply line 4 when fuel gas is supplied to the LNG storage tank 1 as well as a line for supplying fuel to the low pressure gas engine 30.

When the fuel gas is supplied at high pressure for use, the pressure of the fuel gas injected into the LNG storage tank 1 may be too high to damage the LNG storage tank due to impact or erosion. In order to solve this problem, it is possible to solve the above problems by installing a pressure reducing valve 17 in the oil supply line to lower the pressure of fuel gas during oiling and supply the LNG storage tank 1.

In addition, when the fuel gas stored in the fueling source (2) is refueled to the LNG storage tank (1) along the fueling line (4), the fuel gas is refueling fuel supply line (19) branched from the fueling line (4) ) Is supplied to the low pressure gas engine 30 via the low pressure gas fuel supply line 8 and used as fuel.

At this time, since the fuel gas of the gas supply source 2 is supplied in a supercooled state of about 5 to 7 bar pressure, the fuel gas is a low pressure vaporizer 15 so as to be made into a fuel gas condition of an evaporated state that can be used for the low pressure gas engine 30. ) Is supplied to the low pressure gas fuel supply line 8 at the front end.

When refueling the fuel gas of the fuel supply source (2) to the LNG storage tank (1) to discharge the boil-off gas generated in the LNG storage tank (1) to supply to the low-pressure gas fuel supply line (8)-⑤.

At this time, the pressure of the boil-off gas generated in the LNG is a pressure corresponding to the pressure of the fuel gas supplied to the low-pressure gas engine 30, the boil-off gas is a low-pressure gas fuel supply line 8 at the rear end of the low-pressure vaporizer (15) By supplying to the fuel cell, the low pressure gas engine 30 is used as a fuel gas capable of driving the low pressure gas engine 30.

As described above, the fuel gas supply system 100 according to the embodiment of the present invention, in the case of refueling the fuel gas in the conventional LNG storage tank, unlike the fuel gas cannot be used, the fuel gas is supplied to the LNG storage tank from a gas source and At the same time, it is possible to operate the low pressure gas engine while refueling by supplying it to the low pressure gas fuel supply line.

In addition, when fuel gas is refueled to the LNG storage tank at sea instead of fuel gas at the onshore fuel supply base, the generated evaporated gas is burned in the fuel gas supply system 100 according to the embodiment of the present invention. The fuel can be used as a fuel for the low pressure gas engine 30 without being discharged to the atmosphere. On the other hand, when fuel gas is supplied to the LNG storage tank, safety problems such as damage or destruction of the LNG storage tank due to evaporation gas generated are to be considered. There is a need. Therefore, in order to solve this problem, it is necessary to lower the internal pressure of the LNG storage tank to refuel, but at this time, the generated evaporated gas has a low pressure and does not satisfy the conditions that can be supplied to the low pressure gas engine and used as fuel gas. I can't. That is, the fuel gas introduced to drive the low pressure gas engine does not meet the set pressure condition of the low pressure gas engine. Accordingly, through the embodiment of FIG. 3, the boil-off gas generated when fuel gas is supplied to the LNG storage tank may be treated at a low internal pressure of the LNG storage tank.

Figure 3 is a schematic diagram showing a fuel gas supply system according to another embodiment of the present invention.

As shown, the fuel gas supply system 200 according to another embodiment of the present invention is similar to the fuel gas supply system 100 of FIG. 1 described above, and thus description of the configuration having the same function will be omitted. Shall be.

Referring to FIG. 3, the fuel gas supply system 200 may be maintained at an evaporation gas generated in the LNG storage tank 1 or a low pressure during fueling to efficiently process the evaporated gas generated in the LNG storage tank 1. The first branch line 22 branches in the middle of the low pressure gas fuel supply line 8 at the rear end of the pressure regulating means 17 so as to be connected to the low pressure gas fuel supply line 8 again.

In addition, a first ejector 21 is installed in the first branch line 22, and the boil-off gas recovery line 23 branches in the middle of the boil-off gas supply line 6 and is connected to the first ejector 21. . At this time, the third check valve 24 is installed in the first branch line 22 behind the first ejector 21.

The third check valve 24 prevents the flow of fuel gas from the low pressure gas fuel supply line 8 toward the outlet of the first ejector 21 when the first ejector 21 is not used.

The first ejector 21, the first branch line 22, and the boil-off gas recovery line 23 maintain a low internal pressure of the LNG storage tank while supplying fuel gas to the LNG storage tank. Boil off gas can be processed.

That is, the low pressure boil-off gas generated in the LNG storage tank generated when refueling is supplied to the first ejector 21 via the boil-off gas recovery line 23, and at this time, the liquid fuel gas supplied from the fuel source is also supplied. It is supplied to the first ejector 21 via the first branch line 22. In the first ejector 21, the liquid fuel gas and the boil-off gas may be mixed and resupplied to the LNG storage tank to process the low-pressure boil-off gas.

In addition, the second branch line 25 branches in the middle of the low pressure gas fuel supply line 8 after the low pressure vaporizer 15 and is connected to the low pressure gas fuel supply line 8 before the heater 16.

A second ejector 26 is installed in the second branch line 25, and the fuel evaporation gas supply line 27 is branched in the middle of the boil-off gas supply line 6 and connected to the second ejector 26. . At this time, the fourth check valve 28 is installed in the second branch line 25 behind the second ejector 26.

When the fourth check valve 28 is supplied to the low pressure gas engine 30 through the oil supply boil-off gas supply line 27, the second check valve 28 due to the set pressure of the low pressure gas engine 30 To prevent backflow in the direction of

The second ejector 26, the second branch line 25, and the oil supplying boil-off gas supply line 27 are the first ejector 21, the first branch line 22, and the boil-off gas recovery line 23. Similarly, while keeping the internal pressure of the LNG storage tank low, the fuel gas can be treated in the LNG storage tank at the same time to process the low pressure boil-off gas.

That is, the low pressure boil-off gas generated in the LNG storage tank generated when refueling is supplied to the second ejector 26 via the refueling gas supply line 27, and at this time, the liquid fuel supplied from the fuel supply source. Gas is supplied to the second ejector 26 via the low pressure vaporizer 15 and the second branch line 25. In the second ejector 26, the vaporized fuel gas and the boil-off gas may be mixed and maintained at the same pressure (pressure corresponding to the set pressure of the low pressure gas engine) to be supplied as fuel gas to the low pressure gas engine 30. 4 is a view for explaining a fuel gas supply method and a boil-off gas processing method generated in the fuel gas supply system shown in FIG.

Since the supply of the fuel gas stored in the LNG storage tank 1 to the low pressure gas engine 30 and the high pressure gas engine 20 is the same as the embodiment of FIG. 2, the description thereof will be omitted.

Referring to FIG. 4, when refueling, the boil-off gas having a pressure of about 1 to 2 bar generated in the LNG storage tank 1 is first passed through the boil-off gas recovery line 23 along the boil-off gas supply line 6. It may be supplied to the ejector 21. At this time, the liquid fuel gas having a pressure of about 5 ~ 7bar supplied from the fuel supply source 2 is the first ejector over the fuel supply line 4, the low-pressure gas fuel supply line 8 and the first branch line 22 It is supplied to 21 at the same time.

The boil-off gas and the fuel gas are mixed in the first ejector 21 at the same pressure in the liquid phase, and then through the first branch line 22 and the low pressure gas fuel supply line 8 at the rear end of the first ejector 21. Recovered to the LNG storage tank (1).

In addition, the boil-off gas may be supplied to the second ejector 26 via the boil-off boil-off gas supply line 27 along the boil-off gas supply line 6. At this time, the fuel gas supplied from the fuel source 2 is supplied to the fuel supply line 19 for refueling, the low pressure gas fuel supply line 8, the low pressure vaporizer 15, and the second ejector over the second branch line 25. 26).

After the boil-off gas and the fuel gas are mixed in the second ejector 26 at the same pressure, the low pressure gas engine 30 is provided through the second branch line 25 and the heater 16 at the rear end of the second ejector 26. Is supplied.

As such, the other fuel gas supply system 200 according to the embodiment of the present invention may supply fuel gas to the LNG storage tank 1 at the gas supply source 2 and supply the low pressure gas fuel supply line 8 at the same time. In addition, it is possible to recover the low pressure evaporated gas generated during refueling and store it in the LNG storage tank 1 or to efficiently use the fuel gas of the low pressure gas engine 30.

In particular, as in the fuel gas supply system 100 according to an embodiment of the present invention, when fuel gas is refueled to the LNG storage tank at sea, a low pressure boil-off gas is generated according to another embodiment of the present invention. In the gas supply system 200, the gas supply system 200 may be recovered without burning or discharged to the atmosphere and stored in the LNG storage tank 1 or used as fuel gas in the low pressure gas engine 30.

Figure 5 is a schematic diagram showing a fuel gas supply system according to another embodiment of the present invention.

As shown, since the fuel gas supply system 300 according to another embodiment of the present invention is similar to the fuel gas supply system 200 of FIG. 3, the description of the configuration having the same function will be omitted. Shall be.

Referring to FIG. 5, unlike the embodiment of FIG. 3, the fuel gas supply system 300 is maintained at a low pressure or boil-off gas generated in the LNG storage tank 1 when refueling, and is generated in the LNG storage tank 1. The third branch line 22a is branched in the middle of the oil supply line 4 in front of the pressure regulating means 17 so as to efficiently process the boil-off gas, and is connected to the oil supply line 4 again.

A third ejector 21a is installed in the third branch line 22a, and the boil-off gas recovery line 23 branches in the middle of the boil-off gas supply line 6 and is connected to the third ejector 21a.

In addition, the auxiliary oil supply boil-off gas supply line 29 is branched in the middle of the third branch line 22a on the outlet side of the third ejector 21a to supply the low pressure gas fuel in front of the low pressure vaporizer 15. Connected to line 8.

The third branch line 22a, the third ejector 21a, and the auxiliary oil supply boil-off gas supply line 29 are also the first ejector 21 and the first branch of the fuel gas supply system 200 described above. Similar to the line 22 and the boil-off gas recovery line 23, while keeping the internal pressure of the LNG storage tank low, fuel gas can be treated in the LNG storage tank at the same time to process the low-pressure boil-off gas.

That is, the low pressure boil-off gas generated in the LNG storage tank generated when refueling is supplied to the third ejector 21a via the boil-off gas recovery line 23, and at this time, the liquid fuel gas supplied from the gas source is also supplied. It is supplied to the third ejector 21a via the third branch line 22a. In the third ejector 21a, the liquid fuel gas and the boil-off gas may be mixed and resupplied to the LNG storage tank to process the low-pressure boil-off gas.

In addition, the fuel gas of the same pressure in which the liquid fuel gas and the boil-off gas are mixed in the third ejector 21a is passed through the auxiliary refrigeration gas supply line 29, the low-pressure vaporizer 15 and the heater 16, and the low-pressure gas. The low pressure boil-off gas can be treated by supplying it to the engine 30. 6 is a view for explaining a fuel gas supply method and a boil-off gas processing method according to the fuel gas supply system shown in FIG.

Since the supply of the fuel gas stored in the LNG storage tank 1 to the low pressure gas engine 30 and the high pressure gas engine 20 is the same as the embodiment of FIG. 2, the description thereof will be omitted.

Referring to FIG. 6, the boil-off gas generated in the LNG storage tank 1 may be supplied to the third ejector 21a along the boil-off gas supply line 6 via the boil-off gas recovery line 23. . At this time, the fuel gas supplied from the oil supply source 2 is supplied to the third ejector 21a through the oil supply line 4 and the third branch line 22a.

After the boil-off gas and the fuel gas are mixed in the third ejector 21a, the third branch line 22a and the pressure regulating means 17 and the low pressure gas fuel supply line 8 at the rear end of the third ejector 21a It is recovered to the LNG storage tank (1) through.

In addition, after the boil-off gas and fuel gas are mixed in the third ejector 21a, the low-pressure gas in front of the auxiliary refrigeration boil-off gas supply line 29 and the low-pressure vaporizer 15 branched at the third branch line 22a. Via the fuel gas supply line 8, it is supplied to the low pressure gas engine 30 via the low pressure vaporizer 15 and the heater 16 installed in the low pressure gas fuel gas supply line 8.

As such, another fuel gas supply system 300 according to an exemplary embodiment of the present invention may not only supply fuel gas to the LNG storage tank at a gas source, but also supply the low pressure gas fuel supply line with another method. It can recover the boil-off gas generated during refueling and store it in LNG storage tank or use it as fuel gas of low pressure gas engine.

On the other hand, although not shown, the various valves included in the fuel gas supply system (100, 200, 300) according to an embodiment of the present invention may be linked to the control logic system for controlling the LNG supply according to the logic. For example, it may be configured to control the pressure ratio of the fuel gas in the pressure reducing valve 17 or the opening and closing of the first check valve 3 in accordance with the amount of boil-off gas.

In addition, the fuel gas supply system (100, 200, 300) according to an embodiment of the present invention can be applied to all vessels for propulsion using LNG as fuel as well as LNG carriers.

It will be understood by those skilled in the art that various changes and modifications may be made without departing from the scope of the present invention as defined by the appended claims, It is obvious.

1: LNG storage tank 2: gas station
3: first check valve 4: oiling line
5: 2nd check valve 6: boil-off gas supply line
7: boil-off gas treatment line 8: low-pressure gas fuel supply line
10: high pressure gas fuel supply line 11: recondenser
12: high pressure pump 13: high pressure vaporizer
14: pressure damper 15: low pressure vaporizer
16: heater 18: flow control valve
19: fuel supply line 20: high pressure gas engine
21: first ejector 21a: third ejector
22: first branch line 22a: third branch line
23: boil-off gas recovery line 24: third check valve
25: second branch line 26: second ejector
27: oil supply boil-off gas supply line 28: fourth check valve
29: boil-off gas supply line for auxiliary fuel 30: low pressure gas engine

Claims (14)

A low pressure gas fuel supply line connected from the LNG storage tank to the low pressure gas engine;
A low pressure vaporizer and a heater installed in the low pressure gas fuel supply line;
A refueling line connected to the low pressure gas fuel supply line at a refueling source and provided with a pressure regulating means;
An oil supply fuel supply line branched in the middle of the oil supply line in front of the pressure control means and connected to the low pressure gas fuel supply line in front of the low pressure vaporizer;
A first check valve installed at the low pressure gas fuel supply line between a connection end of the oil supply line and the low pressure gas fuel supply line and a connection end of the oil supply fuel supply line and the low pressure gas fuel supply line; And
Flow control means installed in the fuel supply line for fueling
Fuel gas supply system comprising a. delete The method of claim 1,
The pressure regulating means is a fuel gas supply system, characterized in that the pressure reducing valve. The method of claim 1,
And a boil-off gas supply line connected to the low-pressure gas fuel supply line at a rear end of the low-pressure vaporizer from an upper portion of the LNG storage tank. 5. The method of claim 4,
A first branch line branched in the middle of the low pressure gas fuel supply line after the pressure adjusting means;
A first ejector installed in the first branch line,
And a boil-off gas recovery line connected to the first ejector from the boil-off gas supply line. 6. The method of claim 5,
And a second check valve installed at the first branch line at the rear end of the first ejector. 5. The method of claim 4,
A second branch line branched in the middle of the low pressure gas fuel supply line after the low pressure vaporizer;
A second ejector installed at the second branch line,
The fuel gas supply system further comprises a boil-off boil-off gas supply line connected to the second ejector from the boil-off gas supply line. 8. The method of claim 7,
And a third check valve installed at the second branch line after the second ejector. 5. The method of claim 4,
A third branch line branched in the middle of the oiling line in front of the pressure regulating means,
A third ejector installed in the third branch line,
An boil-off gas recovery line connected to the third ejector from the boil-off gas supply line,
And an auxiliary boil-off boil-off gas supply line branched in the middle of the third branch line on the outlet side of the third ejector and connected to the low-pressure gas fuel supply line in front of the low-pressure vaporizer. 5. The method of claim 4,
A high pressure gas fuel supply line branched from the low pressure gas fuel supply line, connected to a high pressure gas engine, and equipped with a recondenser;
And a boil-off gas treatment line branched from the boil-off gas supply line and connected to the recondenser. When fuel gas is supplied to LNG storage tank,
Supplying fuel gas of a fuel supply source to the LNG storage tank via an oil supply line;
At the same time, the fuel gas of the refueling source is vaporized and heated through the carburetor and the heater via the refueling fuel supply line and the low pressure gas fuel supply line, and is supplied to the low pressure gas engine
Fuel gas supply method comprising a. 12. The method of claim 11,
The boil-off gas generated in the LNG storage tank is mixed with the vaporized fuel gas through the vaporizer along the boil-off gas supply line connected to the low-pressure gas fuel supply line is supplied to the low-pressure gas engine via the heater. How to supply fuel gas. 12. The method of claim 11,
When the pressure of the boil-off gas generated in the LNG storage tank is lower than the set pressure of the low-pressure gas engine,
The boil-off gas is mixed with the fuel gas depressurized in the refueling line and recovered to the LNG storage tank. 12. The method of claim 11,
When the pressure of the boil-off gas generated in the LNG storage tank is lower than the set pressure of the low pressure gas engine,
The boil-off gas is mixed with the fuel gas vaporized via the vaporizer along the boil-off gas supply line connected to the low-pressure gas fuel supply line to match the set pressure of the low-pressure gas engine, and passed through the heater to the low-pressure gas engine. Fuel gas supply method characterized in that the supply.

Images