KR20160008810A - Fuel Gas Supply System And Method For Ship Engine - Google Patents

Abstract

A fuel supply system and method for a ship engine is disclosed. According to the present invention, the fuel supply system for a ship engine comprises: an LNG storage tank provided on a ship; a first boil-off gas supply line compressing boil-off gas (BOG) generated in the LNG storage tank to be supplied to a ship engine; and a fuel supply tank storing remaining BOG after the BOG is supplied to the ship engine. In case of a ballast voyage of a ship, a fuel can be supplied to the ship engine from the fuel supply tank.

Description

TECHNICAL FIELD [0001] The present invention relates to a fuel supply system for a marine engine,

The present invention relates to a system and method for supplying fuel to a marine engine, and more particularly to a system and method for supplying fuel to a marine engine, comprising a first evaporation gas supply line for compressing BOG (Boil Off Gas) The present invention relates to a fuel supply system and method for a marine engine that enables a fuel to be supplied from a fuel supply tank to a marine engine during a ballast voyage of a marine vessel, including a fuel supply tank for storing the remaining BOG.

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.

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 of the engine should be redundant in case of disconnection of the engine in case of failure of the equipment.

As shown in FIG. 1, when a high-pressure gas injection engine is configured in a propulsion system in an LNG carrier or the like to supply BOG generated during LNG transportation as fuel for a marine engine, two sets of compressors 10 and 20 must be provided . However, having redundant equipment that is not used for dualization is very costly, and since the compressor consumes a lot of electricity, the cost of system operation is also high. In addition, since the BOG generated when the LNG is full in the cargo tank is large, it can be compressed and supplied as fuel. However, since the BOG generated when the amount of LNG loaded on the cargo tank is small due to unloading of the LNG, Supply becomes difficult.

As shown in FIG. 2, in the case of constructing a high-pressure gas injection engine in which LNG is pumped and vaporized instead of BOG to supply fuel, two sets of pumps 30 and 40 must be provided. However, Because it is relatively low, it can reduce the burden of equipment maintenance cost and consumes LNG stored in cargo tank, so stable fuel supply is possible. On the other hand, there is a problem that a large amount of BOG occurring in a full loading state of LNG is wasted without being utilized.

Therefore, there is a need for a fuel supply system that can rationalize the cost, utilize the generated BOG, and propel the ship with stable fuel even when the amount of generated BOG is small.

According to an aspect of the present invention, there is provided an LNG storage tank provided on a ship;

A first evaporation gas supply line for compressing a Boiling Off Gas (BOG) generated in the LNG storage tank and supplying the compressed boil-off gas to an engine for ship; And

And a fuel supply tank for storing the remaining BOG supplied to the marine engine,

Wherein the fuel supply system is capable of supplying fuel from the fuel supply tank to the marine engine at the ballast voyage of the marine vessel.

Preferably, the gas liquefaction line is branched downstream of the first evaporative gas supply line and further compresses, compresses and liquefies the compressed BOG that remains after being supplied to the marine engine, and a gas liquefying line which is branched from the fuel supply tank and the LNG storage And a forced vaporizing gas supply line for forcibly vaporizing the LNG stored in at least one of the tanks and supplying the vaporized gas to the marine engine.

Preferably, the first compressor is provided in the first evaporation gas supply line and compresses the BOG, a second compressor provided in the gas liquefaction line and further compressing the BOG compressed by the compressor, Further comprising a heat exchanger in which the BOG further compressed in the second compressor is cooled by heat exchange with the BOG to be introduced into the first compressor through the first evaporative gas supply line.

Preferably, a second evaporation gas supply line for supplying BOG generated from the fuel supply tank to the upstream of the first compressor, and a second evaporation gas supply line provided downstream of the heat exchanger in the gas liquefaction line, And a gas-liquid separator for separating the liquid LNG from the BOG monotonically expanded in the expansion means by gas-liquid separation and storing the LNG in the fuel supply tank.

Preferably, the forced vaporizing gas supply line includes a feed pump for pumping the LNG from the fuel supply tank, a vaporizer for supplying the LNG pumped from the feed pump to the vaporizer, and a vaporizer for vaporizing the vaporized natural gas And a heater for receiving the natural gas from which the heavy hydrocarbon component has been separated from the separator and heating the natural gas to a temperature required by the marine engine.

Preferably, a forced vaporizing gas compression line downstream of the separator and connected from the forced vaporizing gas supply line to the upstream of the first compressor of the evaporative gas supply line, and an evaporative gas supply line through the evaporative gas supply line or the forced vapor compression line And a purging unit for purging the heavy hydrocarbon component separated from the separator by natural gas compressed through at least one of the first and second compressors.

Preferably, the heavy hydrocarbon component purged by the purging unit may be supplied to the fuel supply tank or the LNG storage tank.

Preferably, the fuel supply tank may be provided with a pressure-resistant container capable of withstanding a pressure of 9 to 10 bar.

Preferably, the marine engine may be at least one of a 2-stroke engine and a 4-stroke engine that are supplied with compressed natural gas at 3 to 15 bar.

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

The boil off gas (BOG) generated in the LNG storage tank of the ship is compressed and supplied to the marine engine, or the LNG is forcibly vaporized and supplied to the marine engine,

In the laden condition of the ship, the BOG generated in the LNG storage tank is compressed and supplied to the marine engine, while the compressed BOG remaining after the fuel supply is further compressed, cooled and liquefied to be separately provided from the LNG storage tank And the fuel supply tank,

And the fuel is supplied from the fuel supply tank to the marine engine in a ballast condition of the marine vessel.

Preferably, the fuel supply tank may be provided with a pressure-resistant container capable of withstanding a pressure of 9 to 10 bar.

In the fuel supply system and method of a marine engine of the present invention, BOG (Boil Off Gas) generated in the LNG storage tank is compressed and supplied to the marine engine while the remaining BOG is stored in the fuel supply tank. The ballast voyage is designed to supply fuel from the fuel supply tank to the marine engine.

In the laden condition, a large amount of BOG generated in the LNG storage tank of the ship is compressed and supplied to the engine of the marine engine, while remaining BOG is further compressed and stored in the liquefied or pressurized state by using the cold of the BOG itself, The amount of BOG that is burned and wasted can be reduced. In addition, in the ballast condition, the liquefied or pressurized stored fuel can be supplied to the marine engine to effectively utilize the BOG and reduce the burden of shipping the diesel oil due to lack of LNG or BOG fuel in the ballast condition. It is possible to reduce the cost and continue to supply the gaseous fuel during the round trip of the ship, thus realizing environment friendly vessel.

If necessary, liquefied LNG stored in the fuel supply tank may be sent to the LNG storage tank for delivery to the shippers, which can also contribute to the interests of the shippers.

Figure 1 shows a system in which two sets of compressors are provided to supply the BOG to the marine engine as fuel.
Figure 2 schematically shows a system in which two sets of pumps are provided to supply the LNG as fuel to the marine engine.
3 schematically shows a fuel supply system of a marine engine according to an 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.

3 schematically shows a fuel supply system of a marine engine E according to an embodiment of the present invention.

3, the fuel supply system of the marine engine E according to an embodiment of the present invention includes an LNG storage tank LT provided in the ship, a BOG (Boil (BOG) generated in the LNG storage tank LT) And a fuel supply tank (FT) for storing the remaining BOG supplied to the marine engine (E), wherein the first evaporation gas supply line (NBL 1) The ballast voyage allows fuel to be supplied from the fuel supply tank (FT) to the marine engine (E).

To this end, the present embodiment is provided with a gas liquefaction line LL which is branched downstream of the first evaporative gas supply line NBL 1 to further compress and cool the remaining compressed BOG supplied to the marine engine E And then stored in the fuel supply tank FT. Also, a forced vaporizing gas supply line (FBL) is provided for forcibly vaporizing the LNG stored in at least one of the fuel supply tank (FT) and the LNG storage tank (LT) and supplying it to the marine engine (E).

In this embodiment, the marine engine E is an engine capable of receiving compressed natural gas as fuel, and may be a 2-stroke engine and a 4-stroke engine, in particular, supplied with natural gas compressed at 3 to 15 bar, For example, a DF (Dual Fuel) engine such as a DFDE (Dual Fuel Diesel Engine) provided for propulsion or power generation of a ship.

In particular, as described above, in this embodiment, an independent supply line is provided so that BOG or LNG can be appropriately supplied as fuel to the marine engine E under laden and ballast conditions. The laden condition or laden voyage of a ship refers to the time when LNG is loaded into the LNG storage tank (LT) at the time of full loading of LNG carrier, about 98% of the volume of the tank. In this case, LNG storage tank ), The amount of BOG generated is large.

On the other hand, the ballast condition or the ballast voyage means that the LNG stored in the LNG storage tank (LT) is small by unloading the LNG at the destination, and the amount of the BOG generated at that time is also small. This embodiment considers this point while supplying the BOG to the marine engine E, that is, the engine for propulsion or the power generation, in order to effectively utilize the large amount of BOG generated in the LNG storage tank LT of the ship, particularly the LNG carrier. The system is configured to supply fuel efficiently according to Laden condition and Ballast condition.

The amount of BOG in the LNG storage tank (LT) is, for example, 3 to 4 ton / h in the laden condition in the case of a ship having a capacity of 150000 m 3, although there is a difference depending on conditions such as the capacity of the storage tank installed in the ship and the external temperature. And 0.3 to 0.4 ton / h in the ballast condition. In recent years, since the BOR (Boil Off Rate) is lowered due to the improvement of the insulation performance of a ship, the amount of BOG is also decreased. However, in the laden condition, sufficient fuel can be supplied by only BOG, The gas fuel compressed by the marine engine E is supplied through the gas supply line NBL 1 and the remaining BOG is liquefied or compressed in the separate tank after the fuel supply and the fuel stored in the ballast voyage is supplied to the marine engine E).

First, the first evaporator gas supply line NBL 1 is provided with a first compressor 100 for compressing the BOG to a pressure required by the marine engine E, and the gas liquefaction line LL is provided with a BOG The BOG further compressed by the second compressor 200 is exchanged with the BOG to be introduced into the first compressor 100 through the first evaporative gas supply line NBL 1 A heat exchanger 300 for cooling is provided. The gas liquefaction line LL is provided with expansion means 400 for swelling the BOG cooled after further compression at the downstream side of the heat exchanger 300 and gas phase liquid separation from the BOG monotonically expanded at the expansion means 400, Liquid separator 500 for storing the fuel gas in at least one of the fuel supply tank FT and the LNG storage tank LT. Here, when storing the liquid LNG in the fuel supply tank FT, a pump for supplying the liquid LNG may be added because of the internal pressure of the fuel supply tank FT.

The first compressor 100 and the second compressor 200 may be of the same type or different types. For example, the first compressor 100 may be a centrifugal compressor, the second compressor 200 may be a centrifugal compressor, May be provided as a reciprocating compressor. The compressors may be multi-stage compressors provided with a plurality of compressors and an intercooler.

The temperature of the evaporation gas increases as the first and second compressors 100 and 200 compress the refrigerant. The evaporated gas generated in the LNG storage tank LT flows to the first compressor 100 through the heat exchanger 300 to transfer cold heat to the compressed evaporated gas. The heat exchanger 300 may be, for example, a diffused bonded compact heat exchanger (DCHE), and the evaporated gas compressed through heat exchange with the low temperature BOG generated in the LNG storage tank LT and introduced into the first compressor 100 And cooled. Here, the heat exchanger 300 is described as being provided in the gas liquefaction line LL for convenience of explanation, but it is also provided in the first evaporation gas supply line NBL 1.

The BOG cooled and compressed through the compressor and the heat exchanger 300 is thermally expanded through the expansion means 400. The expansion means 400 may be, for example, a line-thomson valve or an expander. The LNG that has been liquefied through the expansion means 400 is separated from the gas-liquid separator 500 and stored in the fuel supply tank FT. The vapor-phase BOG separated from the gas-liquid separator 500 is evaporated at the upstream of the heat exchanger 300 May be supplied to the gas supply line and joined to the BOG to be introduced into the first compressor (100).

At this time, the compressed BOG can be stored in a pressurized state without being liquefied, and then supplied as fuel in the ballast voyage. At this time, the fuel supply tank FT may be provided as a pressure-resistant container capable of withstanding the pressures of () to ( bar ) .

Since the BOG generated from the fuel supply tank FT can also be supplied as the fuel for the marine engine E, the second evaporative gas supply line NBL 2 is provided so as to supply the BOG to the upstream of the first compressor 100 do.

The forced vaporizing gas supply line FBL is provided with a supply pump FP for pumping LNG from the fuel supply tank FT, a vaporizer 600 for supplying and supplying LNG pumped from the supply pump FP to the vaporizer 600, A separator 700 for separating the heavy hydrocarbon component contained in the natural gas vaporized in the natural gas 600 from the separator 700 and a separator 700 for receiving the natural gas from which the heavy hydrocarbon component has been separated from the separator 700, A heater 800 may be provided. At this time, a pump capable of supplying LNG to the LNG storage tank LT may be provided, and LNG may be supplied from the LNG storage tank LT to the forced vaporizing gas supply line FBL, if necessary.

The separator 700 is provided in the forced vaporized gas supply line FBL because the forced vaporized gas can contain a significant amount of the heavy hydrocarbon component contained in the LNG as compared with the BOG in which methane (CH ₄ ) is mostly present.

That is, in addition to methane, natural gas includes hydrocarbon components having a plurality of hydrocarbons such as ethane, propane, butane, and pentane, and inert gas components such as nitrogen and carbon dioxide. The composition ratio varies depending on the place of production. Methane number When the fuel that does not meet the methane required by the engine is supplied, the engine shows a phenomenon of knocking or abnormal combustion such as explosion or combustion before the top dead center of the piston. . Such an abnormal combustion phenomenon may cause wear of the engine piston, and may cause problems such as deterioration of engine efficiency and device failure. The present embodiment can increase the methane price of the fuel to be supplied to the engine to such an extent that the engine needs such that the abnormal combustion phenomenon can be prevented. The DF engine, which can be applied to the marine engine E of this embodiment, generally requires a methane price of 80 or more, and the methane gas of the liquefied natural gas may range from about 70 to about 80 depending on the place of production. Therefore, unlike the case where BOG is supplied as fuel, when the forced vaporized natural gas (FBOG) is supplied, the methane price needs to be adjusted. For this purpose, the separator 700 is provided in this embodiment.

Ethanol, propane, butane, etc., which are heavy hydrocarbon components, have higher liquefaction point than methane. Therefore, in the separator 700, the methane content of the liquefied natural gas is increased to a level required by the engine by removing the liquefied heavy hydrocarbons at a temperature at which the heavy hydrocarbon components such as propane and butane become liquid state while maintaining the gas state .

The vaporization temperature of the liquefied natural gas pumped in the tank and heated in the vaporizer 600 is in the range of -80 to -120 DEG C and the vaporization temperature or the temperature of the separator 700 is adjusted in consideration of different compositions depending on the place where the liquefied natural gas is produced The methane value of the FBOG can be controlled. However, since the LNG stored in the fuel supply tank FT is obtained by liquefying the BOG generated from the LNG storage tank LT, the FBOG supplied from the fuel supply tank FT and forcedly vaporized may not require a large amount of methane adjustment.

On the other hand, in this embodiment, the forced vaporized gas compression line PL connected downstream of the separator 700 from the forced vaporized gas supply line FBL to the upstream of the first compressor 100 of the evaporated gas supply line, Purging a heavy hydrocarbon component separated from the separator (700) by natural gas compressed through at least one of the first and second compressors (100, 200) through a line or a forced vaporizing gas compression line (PL) Unit 750 as shown in FIG. The heating value can be maintained at a proper level by purging the heavy hydrocarbon component separated from the separator 700 through the purging unit 750.

The heavy hydrocarbon component purged by the purging unit 750 may be supplied to the fuel supply tank FT or the LNG storage tank LT and stored. Alternatively, a separate tank may be provided and stored.

Meanwhile, the BOG remaining after the fuel supply can be liquefied, but a combined IGG (Inert Gas Generator) / GCU (Gas Conversion Unit) 900 ) May be provided. The BOG generated in the ballast condition can also be compressed and liquefied or supplied as fuel. However, since the electric consumption of the compressor compressing the gas is so large as to be known to be 10 times the electric consumption of the pump, a small amount of BOG generated in the ballast condition It may be more economical to burn or remove the inert gas than to compress it by liquefying it with a compressor or to generate and consume the inert gas necessary for the ship. Therefore, the present embodiment can provide a combined IGG / GCU 900 for this purpose.

As described above, according to the present embodiment, the BOG generated in the LNG storage tank LT is compressed and supplied to the marine engine E, while the remaining BOG supplied to the marine engine E is supplied to the fuel supply tank (FT), and designed to supply fuel from the fuel supply tank (FT) to the marine engine (E) during the ballast voyage.

The remaining BOG is stored in liquefied or pressurized state while supplying a large amount of BOG generated in the laden condition, and the fuel stored in the ballast condition is supplied to the marine engine (E) You can use BOG effectively while reducing the amount. This will reduce the operating cost of the vessel and reduce the use of diesel fuel, thereby enabling eco-friendly vessels to be implemented.

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.

LT: LNG storage tank
FT: fuel supply tank
E: Marine engine
FP: Feed pump
P: Pump
NBL 1: first evaporation gas supply line
NBL 2: second evaporation gas supply line
FBL: Forced vaporizing gas supply line
LL: Gas Liquefaction Line
PL: Forced gas compression line
100: first compressor
200: Second compressor
300: heat exchanger
400: expansion means
500: gas-liquid separator
600: vaporizer
700: separator
750: Purging unit
800: heater
900: combined IGG / GCU

Claims (11)

An LNG storage tank provided on the ship;
A first evaporation gas supply line for compressing a Boiling Off Gas (BOG) generated in the LNG storage tank and supplying the compressed boil-off gas to an engine for ship; And
And a fuel supply tank for storing the remaining BOG supplied to the marine engine,
Wherein the fuel supply system is capable of supplying fuel from the fuel supply tank to the marine engine at the ballast voyage of the marine vessel. The method according to claim 1,
A gas liquefier branching downstream of the first evaporative gas supply line and further compressing and compressing the compressed BOG remaining after being supplied to the marine engine to liquefy; And
Further comprising a forced vaporizing gas supply line for forcibly vaporizing the LNG stored in at least one of the fuel supply tank and the LNG storage tank and supplying the LNG to the marine engine. 3. The method of claim 2,
A first compressor provided in the first evaporation gas supply line and compressing the BOG;
A second compressor provided in the gas liquefaction line for further compressing the BOG compressed in the compressor; And
Wherein the BOG further compressed in the second compressor is cooled by heat exchange with the BOG to be introduced into the first compressor through the first evaporative gas supply line. The method of claim 3,
A second evaporation gas supply line for supplying BOG generated from the fuel supply tank to an upstream side of the first compressor;
Expanding means provided in the gas liquefaction line downstream of the heat exchanger for monotonically expanding the BOG cooled after further compression; And
Further comprising a gas-liquid separator for separating the liquid LNG from the BOG which is thermally expanded in the expansion means by vapor-liquid separation and storing the liquid LNG in the fuel supply tank. The method as claimed in claim 4, wherein the forced vaporizing gas supply line
A feed pump for pumping the LNG from the fuel supply tank;
A vaporizer for supplying the LNG pumped from the supply pump and forcibly vaporizing the LNG;
A separator for separating the heavy hydrocarbon component contained in the natural gas vaporized in the vaporizer; And
And a heater for receiving the natural gas from which the heavy hydrocarbon component is separated from the separator and heating the natural gas to a temperature required by the marine engine. 6. The method of claim 5,
A forced vaporizing gas compression line downstream of the separator and connected from the forced vaporizing gas supply line to the first compressor upstream of the vaporized gas supply line; And
Further comprising a purging unit for purging the heavy hydrocarbon components separated from the separator by natural gas compressed through at least one of the first and second compressors through the evaporation gas supply line or the forced gasification gas compression line The engine's fuel supply system. The method according to claim 6,
Wherein the heavy hydrocarbon component purged by the purging unit is supplied to the fuel supply tank or the LNG storage tank. The method according to claim 1,
Wherein the fuel supply tank is provided with a pressure-resistant container capable of withstanding a pressure of 9 to 10 bar. The method according to claim 1,
Wherein the marine engine is at least one of a 2-stroke engine and a 4-stroke engine supplied with natural gas compressed at 3 to 15 bar. A method of supplying a fuel for a marine engine,
The boil off gas (BOG) generated in the LNG storage tank of the ship is compressed and supplied to the marine engine, or the LNG is forcibly vaporized and supplied to the marine engine,
In the laden condition of the ship, the BOG generated in the LNG storage tank is compressed and supplied to the marine engine, while the compressed BOG remaining after the fuel supply is further compressed, cooled and liquefied to be separately provided from the LNG storage tank And the fuel supply tank,
And the fuel is supplied from the fuel supply tank to the marine engine in a ballast condition of the marine vessel. 11. The method of claim 10,
Wherein the fuel supply tank is provided with a pressure-resistant container capable of withstanding a pressure of 9 to 10 bar.

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