KR101439942B1 - Hybrid Fuel Supply Method For Ship Engine - Google Patents

Abstract

A hybrid fuel supply method for a marine engine is disclosed. A hybrid fuel supply method for a marine engine according to the present invention is a method for supplying a fuel for a marine engine in which a BOG generated from an LNG stored in an LNG storage tank of a ship satisfies a fuel required amount of a marine engine, The LNG is compressed and forcedly vaporized and supplied to the marine engine.

Description

Technical Field [0001] The present invention relates to a hybrid fuel supply method,

The present invention relates to a hybrid fuel supply method for a marine engine, and more particularly, to a hybrid fuel supply method for a marine engine, more specifically, when BOG generated from an LNG stored in a LNG storage tank of a ship meets a fuel required amount of a marine engine, And a method of supplying fuel to a marine engine for supplying LNG to a marine engine by compression and forced vaporization if the amount of fuel is less than the required amount.

Liquefied natural gas (hereinafter referred to as "LNG") is a colorless transparent liquid obtained by cooling methane-based natural gas to about -162 ° C. and liquefying it. / 600. ≪ / RTI > Therefore, it is very efficient to transport liquefied LNG when transporting natural gas. For example, an LNG carrier that can transport (transport) LNG is used.

Since the liquefaction temperature of natural gas is a cryogenic temperature of -163 ° C at normal pressure, LNG is easily evaporated even if its temperature is slightly higher than the normal pressure of -163 ° C. LNG storage tanks of LNG carriers are heat-treated, but since external heat is continuously transferred to LNG storage tanks, LNG is constantly spontaneously vaporized in LNG storage tanks during LNG transportation by LNG carrier, Boil-off gas (BOG) is generated in the storage tank.

BOG is a kind of LNG loss, which is an important problem in the transport efficiency of LNG. When the evaporation gas accumulates in the LNG storage tank, the pressure in the LNG storage tank is excessively increased, Have been studied.

Recently, for the treatment of BOG, BOG is re-liquefied and returned to the storage tank, and BOG is used as energy source of engine of ship. In addition, the surplus BOG is combusted in a gas combustion unit (GCU).

The gas combustion unit burns surplus BOG inevitably for regulating the pressure of the storage tank when the BOG can not be utilized otherwise, resulting in a problem that the chemical energy possessed by the BOG is wasted by combustion.

When a dual fuel (DF) engine is applied as the main propulsion unit in the propulsion system of the LNG carriers, the evaporative gas generated in the LNG storage tank can be used as the fuel of the DF engine to process the evaporative gas, If the amount of evaporative gas generated in the LNG storage tank exceeds the amount of fuel used in the propulsion of the ship in the DF engine, the evaporation gas may be sent to a gas burner to incinerate it to protect the LNG storage tank.

Application No. 10-2010-0116987

DF engines are being used as propulsion systems for ships, and engines that use high-pressure gas injection are being developed. In such a propulsion system of the ship, the fuel supply device of the engine may be provided in a binary manner in preparation for the shutdown of the engine in the event of a failure of the apparatus.

When a high-pressure gas injection engine is configured as a propulsion system in an LNG carrier and the BOG generated during LNG transportation is supplied as fuel for a marine engine, two sets of compressors are provided. When the LNG is filled in the cargo tank, It is possible to supply the fuel by compressing it. However, it is difficult to supply sufficient fuel because the amount of BOG generated when the amount of LNG loaded on the cargo tank is small due to unloading of LNG.

Compressed and vaporized LNG instead of BOG, which constitutes a high-pressure gas injection engine that is supplied as fuel, consumes LNG stored in a cargo tank, so that stable fuel supply is possible. However, a large amount of BOG generated under full loading of LNG is not utilized There is a problem that can not be wasted.

Therefore, there is a need for a fuel supply method capable of steadily supplying fuel even when the amount of BOG generated is small, while fully utilizing the generated BOG.

According to an aspect of the present invention, in a method of supplying fuel to a marine engine,

The BOG is compressed and supplied when the BOG generated from the LNG stored in the LNG storage tank of the ship meets the fuel required amount of the marine engine. When the generated amount of the BOG is less than the required fuel amount, the LNG is compressed and forcedly vaporized And the engine is supplied to the marine engine.

In the marine engine, the compressed BOG is supplied as fuel in the laden condition of the ship, and the LNG can be supplied and compressed by the compression and forced vaporization in the ballast condition of the ship.

The BOG can be compressed in multiple stages via a plurality of compressors and a plurality of intercoolers.

The marine engine may be a high-pressure gas injection engine using a high-pressure gas compressed at a high pressure of 150 to 400 bar as fuel.

The ship may be an LNG carrier having a capacity of 130,000 to 35,000 m3.

At least a part of the BOG compressed through at least a part of the plurality of compressors and the plurality of intercoolers can be supplied to the DF engine provided in the ship.

The remaining BOG supplied to the marine engine and the DF engine may be burned.

According to another aspect of the present invention, there is provided a method of supplying fuel to a marine engine,

Means for compressing the BOG generated in the LNG stored in the LNG storage tank of the ship to supply the marine engine; and means for compressing and forcibly vaporizing the LNG to supply it to the marine engine,

Wherein the marine engine is supplied with the compressed BOG as fuel in a laden condition of the marine vessel and is supplied and driven by compression and forced vaporization of the LNG in a ballast condition of the marine vessel. / RTI >

A method for supplying a hybrid fuel for a marine engine of the present invention is a method for supplying BOG to a ship equipped with a high-pressure gas injection engine, wherein the BOG generated from the LNG stored in the LNG storage tank of the ship satisfies the fuel requirement of the marine engine, If the generated amount is less than the required amount of fuel, the LNG is compressed and forcedly vaporized and supplied to the marine engine. Thus, by compressing a large amount of BOG generated in the LNG storage tank of the ship and supplying it as fuel to the high-pressure gas injection engine, it is possible to reduce the amount of wasted BOG in the GCU and effectively utilize the BOG. When the amount of generated BOG is small By supplying the liquefied natural gas to the high-pressure gas injection engine, the fuel can be stably supplied.

1 schematically shows a fuel supply system to which a hybrid fuel supply method of a marine engine according to a first embodiment of the present invention is applied.
2 schematically shows a hybrid fuel supply system according to a second embodiment of the present invention.

In order to fully understand the present invention, operational advantages of the present invention, and objects achieved by the practice of the present invention, reference should be made to the accompanying drawings and the accompanying drawings which illustrate preferred embodiments of the present invention.

Hereinafter, the present invention will be described in detail with reference to the preferred embodiments of the present invention with reference to the accompanying drawings. Like reference symbols in the drawings denote like elements.

1 schematically shows a fuel supply system to which a hybrid fuel supply method of a marine engine according to a first embodiment of the present invention is applied.

As shown in FIG. 1, the hybrid fuel supply system and the fuel supply method of the marine engine of the present embodiment are systems for supplying fuel to the marine engine, and are connected to the LNG storage tank CT of the ship, A first flow path L1 for supplying a boil off gas (BOG) generated from the liquefied natural gas stored in the ship to the high pressure gas injection engine 100 of the ship, and a second flow path L1 for compressing the liquefied natural gas stored in the LNG storage tank CT of the ship And a second flow path L2 for supplying the gas to the high-pressure gas injection engine 100 is provided.

The second flow path L2 is provided with a high pressure pump 300 for receiving the liquefied natural gas from the LNG storage tank CT and compressing the liquefied natural gas from the LNG storage tank CT to a high pressure, The LNG storage tank CT may be provided with a fuel pump 320 for supplying liquefied natural gas to the high pressure pump 300.

In this embodiment, the marine engine is a high-pressure gas injection engine 100 using a high-pressure gas compressed at a high pressure of 150 to 400 bar as a fuel, and a multistage compressor 100 for compressing BOG at 150 to 400 bar in the first flow path L1. (200) may be provided.

In this hybrid fuel supply system, when the BOG generated in the LNG storage tank CT satisfies the fuel required amount of the high-pressure gas injection engine 100, the BOG is supplied to the first flow path L1, The compressed and vaporized liquefied natural gas can be supplied.

The high-pressure gas injection engine 100 compresses the BOG compressed by the multi-stage compressor 200 in the laden condition of the ship, and compresses the liquefied natural gas stored in the LNG storage tank CT under the ballast condition of the ship And can be supplied and vaporized.

The laden condition of a ship refers to the time when LNG is fully loaded into the LNG storage tank (CT), and 98% of the tank volume is normally loaded. In this case, the LNG storage tank (CT) There is a lot of BOG to do. The ballast condition is the amount of LNG stored in the LNG storage tank (CT) due to unloading of the LNG. In this embodiment, the BOG is supplied to the propulsion engine of the ship so that a large amount of BOG generated in the LNG storage tank (CT) of the ship, especially the LNG carrier, can be effectively utilized. The system was configured to effectively supply fuel to the propulsion engine.

According to this situation, a hybrid system capable of supplying BOG and LNG as fuel can be configured to meet the redundancy and reduce the power consumed for fueling the engine.

Redundancy means that redundant equipment is configured and placed in a standby state when the main constituent equipment is in operation to perform the requested function, and when the main constituent equipment fails to operate due to a failure, Redundant designs are designed to overcome this redundancy, mainly for rotating equipment. The fuel supply method in this embodiment corresponds to a multi-stage compressor or a high-pressure pump for compression. The present embodiment is configured to constitute a fuel supply flow path that is mutually divided into a first flow path L1 and a second flow path L2 so that redundant equipment provided only to satisfy redundancy without being normally used, The compressor may not be configured.

When the LNG is compressed and vaporized through the high pressure pump 300 and the forced vaporizer 310 when the power required to compress the BOG by the pressure required for the propulsion engine of the ship is 100, The power consumption is only about 10. It is possible to completely re-liquefy a large amount of BOG generated in the laden condition and use only the high-pressure pump 300 and the forced vaporizer 310. However, in this case, the power consumption in the liquefaction device (not shown) .

When the LNG carriers are operated in the laden / ballast condition by using the hybrid fuel supply system, power consumption of about 55 is consumed. Therefore, less power is consumed to supply the fuel than only the BOG alone or the LNG alone.

In this embodiment and the drawings, there is shown a system in which one high-pressure pump 300 and a forced vaporizer 310 are provided, respectively. However, in the second flow path for supplying LNG to the high-pressure gas injection engine 100 to satisfy the redundancy, A high-pressure pump may be provided.

The multi-stage compressor 200 may include a plurality of compressors 201 and a plurality of intercoolers (intercoolers) 202, and the multi-stage compressor 200 may include only one set of multi- .

However, it is preferable to configure only one set of the multi-stage compressors 200 because the present embodiment constitutes the dual fuel supply passage as described above. However, BOG generated in the LNG storage tank CT can be stably supplied to the high- An additional compressor (not shown) may be configured to supply fuel to the injection engine 100 to consume the BOG.

The high-pressure gas injection engine 100 may be, for example, an ME-GI (Main Engine Gas Injection) engine which is supplied with high-pressure gas as a fuel compressed to 150 to 400 bar.

One or two propulsion engines for ships, such as the ME-GI engine, may be provided.

The ME-GI engine is a high-pressure natural gas injection engine for LNG carriers developed to reduce nitrogen oxides (NOx) and sulfur oxides (SOx) emissions. The ME-GI engine can be installed on marine structures such as LNG carriers that store LNG (Liquefied Natural Gas) in cryogenic storage tanks and carry it. They use natural gas and oil as fuel, The gas supply pressure of 150-400 bara (absolute pressure) is required. Compared with the diesel engine of the same output, the next generation that can reduce pollutant emission by 23%, nitrogen compound 80% and sulfur compound 95% Friendly engine.

In order to process boil off gas (BOG) generated in the LNG storage tank (CT), even in the case of a marine structure or a ship equipped with an ME-GI engine that compresses LNG and consumes it as fuel by forced vaporization, And a BOG processing device such as a GCU (Relative Response) device and a GCU (Gas Combustion Unit) 410. However, the present embodiment can provide a hybrid fuel supply system that selectively supplies BOG and LNG as fuel, The amount of BOG liquefied or burned or vented can be reduced.

The hybrid fueling system can operate according to the amount of BOG generated in the LNG storage tank (CT) as follows.

First, when the amount of generated BOG such as laden condition is large and the required fuel amount of the high-pressure gas injection engine 100 is satisfied, the high-pressure gas injection engine 100 is required as the multistage compressor 200 provided in the first flow path L1 And then supplied.

The multi-stage compressor 200 may have a multi-stage configuration in which a plurality of compressors 201 and a plurality of intercoolers 202 are alternately arranged as described above. This may be a temperature of the natural gas required by the high- And pressure conditions.

Next, in a case where a ballast condition in which the amount of BOG generated in the LNG storage tank CT is small or a device abnormality occurs in the first flow path L1, Pressure, for example, 150 to 400 bara in the case of the ME-GI engine, and supplies the liquefied natural gas, which has been forcedly vaporized through the forced vaporizer 310, to the high-pressure gas injection engine 100. At this time, the high-pressure pump 300 is provided on the upper deck. The liquefied natural gas stored in the LNG storage tank CT is transferred to the high-pressure pump 300 by the FG pump 320.

However, since the liquefied natural gas compressed in the high-pressure pump 300 is in a supercritical state at a critical pressure or more, it does not mean that the vaporization in the forced vaporizer 310 causes a phase change from liquid to gas, It means supplying heat energy to liquefied natural gas.

In this embodiment, the BOG that branches off from the first flow path L1 and exceeds the fuel required amount of the high-pressure gas injection engine 100 is supplied to the DF (Dual Fuel) engine 400 or the GCU 410 (Gas Combustion Unit) And a third flow path L3.

The DF engine 400 may be a Dual Fuel Diesel Electric (DFDE) or a Dual Fuel Diesel Generator (DFDG).

The DF engine 400 is an engine that mixes heavy oil and natural gas and uses the fuel as fuel. Therefore, the sulfur content of the exhaust gas is smaller than that of heavy fuel oil alone.

In the present embodiment, the third flow path L3 is a portion of the multi-stage compressor 200 in which the compressor 201 and the intercooler 202 are configured in multiple stages, And may be branched from one flow path L1.

The ship may be an LNG carrier of 130,000-350,000 m3 class.

For example, in a ship with a capacity of 150000 cubic meters, BOG of 3 to 4 ton / h in laden condition and 0.3 to 0.4 ton / h in ballast condition is changed to LNG It is known to occur in storage tanks (CT). In ME-GI engine, which is a kind of high-pressure gas injection engine 100, 1 to 4 ton / h of fuel is required depending on the load and 0.3 to 0.5 ton / h of fuel is required in case of DFDG. Accordingly, the BOG supply to the DF engine 400 such as the DFDG is not continuous but the BOG generated from the LNG storage tank CT is collected in the ballast condition. When the internal pressure of the tank is increased, the BOG is intermittently supplied to the DF engine 400 And the internal pressure of the tank is lowered.

On the other hand, the BOR (Boil Off Rate) is decreasing with the improvement of the insulation performance of the ship.

According to another aspect of the present invention, there is provided a method of supplying fuel to a marine engine,

When the BOG generated from the liquefied natural gas stored in the LNG storage tank CT of the ship meets the fuel required amount of the propelling high-pressure gas injection engine 100 of the ship, the BOG is compressed and supplied to the high- Pressure gas injection engine 100. The high-pressure gas injection engine 100 compresses and pressurizes the high-pressure gas compressed to a high pressure of 150 to 400 bar into the high-pressure gas injection engine 100, And a hybrid fuel supply method of the marine engine is provided.

The compressor 200 may be provided with only one set including a plurality of compressors 201 and a plurality of intercoolers 202, each of which is composed of a plurality of stages.

As described above, the hybrid fuel supply system and method of the present marine engine includes a first flow path L1 and a second flow path L2 in a vessel equipped with the high-pressure gas injection engine 100, (BOG) of the high-pressure gas injection engine 100 when the BOG generated by the high-pressure gas injection engine 100 satisfies the required fuel amount, the BOG is discharged to the first flow path L1, And supplies it to the engine 100 for supply at the same time.

When a large amount of BOG is generated in the LNG storage tank CT of the ship, for example, in the laden condition of the ship, the BOG is compressed and supplied to the high-pressure gas injection engine 100. When the amount of BOG is small, For example, in a ballast condition, a system configured to supply a liquefied natural gas with a high-pressure gas injection engine 100 can satisfy the redundancy and can stably supply fuel to the engine and reduce the power consumed in the fuel supply And can reduce the amount of BOG that is burned or vented in the GCU 410 and effectively utilize the BOG.

In addition, the first and second flow paths L1 and L2 constitute a compact system by reducing the number of compressors by constituting only one set of compressors 200 while satisfying the redundancy, thereby reducing the installation and management cost of the system can do.

2 is a configuration diagram showing a hybrid fuel supply system according to a second embodiment of the present invention. The hybrid fuel supply system of the present invention can be applied to an LNG carrier or the like equipped with, for example, a MEGI engine as a propulsion main engine.

Referring to FIG. 2, a hybrid fuel supply system 1000 according to an embodiment of the present invention provides a path for transferring an LNG from a cargo tank 1 to a main engine 3 A fuel supply line 1110 and a BOG line 1140 for providing a path for transferring BOG generated from the storage tank 1 to the main engine 3. The hybrid fuel supply system 1000 using the BOG according to an embodiment of the present invention may further include an LNG pump 1120 and an LNG vaporizer 1130 via a fuel supply line 1110. [ The BOG compressor 1150 supplies BOG to the main engine 1 as fuel and the BOG compressor 1150 supplies the main engine 1 as fuel to the main engine 1 through the BOG line 1140. [ And supplies the surplus BOG to the integrated IGG / GCU system 1200.

The fuel supply line 1110 provides a path for transferring the LNG supplied by the drive of the transfer pump 2 from the storage tank 1 of the LNGC as fuel to the main engine 3 and the LNG pump 1120, And an LNG vaporizer 1130 are installed.

The LNG pump 1120 is installed to supply the pumping force necessary for transferring the LNG to the fuel supply line 1110. For example, an LNG HP pump (LNG High Pressure pump) may be used. In this embodiment, .

The LNG vaporizer 1130 is installed at the rear end of the LNG pump 1120 in the fuel supply line 1110 so as to vaporize the LNG transferred by the LNG pump 1120. In order to vaporize the LNG, And the heat is circulated through the circulation line 1131. As another example, various heating means may be used to provide the heat of vaporization of the LNG including the heater. Also, the LNG vaporizer 1130 may be a high pressure vaporizer that can be used at a high pressure for vaporizing the LNG. Meanwhile, steam generated from a boiler or the like can be used as the fruit to be circulated and supplied to the fruit circulation line 1131, for example.

The BOG line 1140 provides a path for transferring the BOG generated naturally from the storage tank 1 to the main engine 3 and is connected to the fuel supply line 1110 as in the present embodiment, To the engine 3, or alternatively it may provide a path for supplying the BOG directly to the main engine 3.

The BOG compressor 1150 is installed in the BOG line 1140 to compress the BOG passing through the BOG line 1140 and is connected to the branch of the redundant BOG line 1160 in the BOG line 1140 as in the present embodiment, So that it is possible to reduce the economic burden due to the installation of the expensive BOG compressor 1150 and the burden on maintenance and repair.

The surplus BOG line 1160 provides a path from the BOG compressor 1150 to the integrated IGG / GCU system 1200 for providing surplus BOG to the integrated IGG / GCU system 1200. In addition to the integrated IGG / GCU system 1200, Can be supplied as fuel.

The integrated IGG / GCU system 1200 is an integrated system of an IGG (Inert Gas Generator) and a GCU (Gas Combustion Unit).

The surplus BOG line 1160 and the fuel supply line 1110 may be connected to each other by a connection line 1170. Thus, the excess BOG can be used as the fuel for the main engine 1 by the connection line 1170, or the vaporized LNG can be used as fuel for the integrated IGG / GCU system 1200. [ The connection line 1170 may be provided with a heater 1180 for heating BOG or vaporized LNG passing therethrough and may be a pressure reduction valve for reducing excessive pressure by controlling the pressure by BOG or vaporized LNG. Valve (PRV) 1190 may be installed. Meanwhile, the heater 1180 may be a gas heater using the heat of combustion of gas, or various heating means may be used as well as a heat circulation supply unit that provides a heat source for heating by circulation of the heat.

The operation of the hybrid fuel supply system according to the present invention will now be described.

When the pressure in the storage tank 1 is equal to or higher than a predetermined pressure, the BOG is compressed by driving the BOG compressor 1150 to be supplied to the main engine 1 as fuel to adjust the pressure in the storage tank 1 do. When the pressure in the storage tank 1 is less than a predetermined pressure, the LNG pump 1120 and the LNG vaporizer 1130 are driven to transfer and vaporize the LNG to be supplied to the main engine 1 as fuel, So that the pressure in the tank 1 can be adjusted.

The surplus BOG from the BOG compressor 1150 is supplied to the integrated IGG / GCU system 1200 through the surplus BOG line 1160 to generate an inert gas to be consumed or supplied to the storage tank 1 So that it can be used as fuel for auxiliary engines and the like.

The integrated IGG / GCU system 1200 to which the BOG is supplied can consume the BOG continuously generated from the storage tank 1 by BOG combustion in the main body (not shown) A combustion gas may be generated as an inert gas for supplying.

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Accordingly, such modifications or variations are intended to fall within the scope of the appended claims.

L1: first flow
L2:
L3: Third Euro
CT: LNG storage tank
100: High-pressure gas injection engine
200: compressor
201: Compressor
202: intercooler
300: High pressure pump
310: forced vaporizer
320: Fuel pump
400: DF engine
410: GCU

Claims (8)

A method of supplying a fuel for a marine engine,
The BOG is compressed and supplied when the BOG generated from the LNG stored in the LNG storage tank of the ship meets the fuel required amount of the marine engine. When the generated amount of the BOG is less than the required fuel amount, the LNG is compressed and forcedly vaporized Ship engine,
The marine engine uses a high-pressure gas compressed to a high pressure of 150 to 400 bar as fuel,
Wherein the BOG compressed through at least a portion of the compressed multi-stages is supplied to a DF engine provided on the ship. The method according to claim 1,
Wherein the marine engine is supplied with the compressed BOG as fuel in a laden condition of the marine vessel and is supplied and driven by compression and forced vaporization of the LNG in a ballast condition of the marine vessel. . The method according to claim 1,
Wherein the BOG is compressed in multiple stages via a plurality of compressors and a plurality of intercoolers. The method according to claim 1,
Wherein the re-liquefaction system using a separate refrigerant cycle for re-liquefaction of the BOG is not provided. The method according to claim 1,
Wherein the ship is an LNG carrier with a capacity of 130,000 to 35,000 m3. The method of claim 3,
Wherein at least a part of the BOG compressed through at least a part of the plurality of compressors and the plurality of intercoolers is supplied to a DF engine provided in the ship. The method according to claim 6,
Wherein the BOG that is supplied to the marine engine and the DF engine is burned. A method of supplying a fuel for a marine engine,
Means for compressing the BOG generated in the LNG stored in the LNG storage tank of the ship to supply the marine engine; and means for compressing and forcibly vaporizing the LNG to supply it to the marine engine,
The marine engine uses high pressure gas compressed at a high pressure of 150 to 400 bar as a fuel. In the laden condition of the ship, the compressed BOG is supplied as fuel. In the ballast condition of the ship, the LNG is compressed and forced Vaporized, supplied and driven,
Wherein the BOG compressed through at least a portion of the means for compressing the BOG is supplied to a DF engine provided on the ship.

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