KR101623098B1 - Fuel Supply System And Method For Ship Or Offshore Platform - Google Patents

Abstract

A fuel supply system and method for a ship or an offshore structure is disclosed. The fuel supply system of the present invention is a fuel supply system for a ship or an offshore structure in which a boil-off gas generated in a storage tank of the ship or an offshore structure is supplied as fuel to an engine of the ship or an offshore structure BOG supply line; An LNG supply line for supplying LNG stored in the storage tank of the ship or the offshore structure as fuel to the engine; an evaporative gas compressor provided in the BOG supply line for compressing the evaporative gas; And a booster pump provided in the BOG supply line for boosting the evaporation gas, wherein the evaporation gas is compressed to a medium pressure in the evaporative gas compressor, and further boosted by the booster pump to be supplied to the engine .

Description

TECHNICAL FIELD [0001] The present invention relates to a fuel supply system and method for a ship or an offshore structure,

The present invention relates to a fuel supply system and method for a ship or an offshore structure, and more particularly, to a system for supplying a BOG or LNG as fuel to an engine including a BOG supply line and an LNG supply line, The present invention relates to a fuel supply system and a method for supplying a compressed gas to an engine by further boosting the compressed evaporated gas with a booster pump by providing an evaporative gas compressor for compressing the evaporated gas.

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 -163 ℃ at normal pressure, LNG easily evaporates even if the temperature is slightly higher than -163 ℃. 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. And, for surplus BOG, the gas combustion unit (GCU) uses a method of burning.

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

For ships consuming LNG as engine fuel, there is a problem of handling a large amount of evaporative gas (BOG) generated in the storage tank. When the LNG storage amount of the storage tank is reduced, The amount of generated fuel is reduced and the fuel supply may become insufficient. In the case of a high-pressure engine such as the ME-GI engine, the power consumption of the compressor for compressing BOG to a high pressure of 200 bar or more is very problematic.

The present invention solves this problem and proposes a fuel supply system capable of supplying both LNG and BOG as fuel to the engine while compressing the BOG with less power consumption and supplying the fuel.

According to an aspect of the present invention, in a fuel supply system for a ship or an offshore structure,

A BOG supply line for supplying boil-off gas generated from the storage tank of the ship or the offshore structure to the engine of the ship or the offshore structure as fuel;

An LNG supply line for supplying the engine with stored LNG from a storage tank of the ship or an offshore structure;

An evaporative gas compressor provided in the BOG supply line for compressing the evaporative gas; And

And a booster pump provided in the BOG supply line for boosting the evaporation gas,

And the evaporated gas is compressed to a medium pressure in the evaporative gas compressor and then further boosted and supplied to the engine.

Preferably, the booster pump may be a pump capable of simultaneously treating gas and liquid.

Preferably, the apparatus further comprises a re-liquefaction section for re-liquefying the evaporated gas boosted by the booster pump, and a re-liquefaction line provided with the re-liquefaction section, wherein the evaporation gas passed through the re- Can be supplied to the front end of the supply line.

Preferably, the booster pump is provided in the LNG supply line and compresses the LNG. And an interconnect line branched from the LNG supply line and connected to the booster pump at a front end of the boosting pump.

The LNG supply line may further include a vaporizer provided in the LNG supply line for vaporizing the LNG compressed by the boosting pump and a gas line branched from the LNG supply line at a rear end of the boosting pump and connected to a rear end of the booster pump, , And the evaporation gas generated in the boosting pump can be supplied to the re-cure unit through the gas line.

Preferably, the apparatus further comprises a first shut-off valve provided at a front end of the boosting pump in the LNG supply line, and a second shut-off valve provided in the interconnect line, When supplied to the LNG supply line, the LNG supply line connected to the booster pump through the first shutoff valve may be shut off.

Preferably, the booster pump and the boosting pump may be provided with a plurality of pumps in parallel.

Preferably, the evaporative gas compressor may be a compressor sealed in an oil-free type, including a centrifugal compressor, a screw compressor, and a reciprocating compressor .

According to another aspect of the present invention, there is provided a method of supplying fuel to a ship or an offshore structure,

1) The LNG stored in the storage tank of the ship or the marine structure is pumped and vaporized and supplied to the engine,

2) The boil-off gas generated in the storage tank is compressed to a medium pressure by a compressor, then is boosted by a booster pump and supplied to the engine,

Wherein the evaporating gas raised in the booster pump or the evaporation gas generated in pumping the LNG is re-liquefied and then stored in the storage tank or boosted by the booster pump and supplied to the engine. / RTI >

Preferably, the booster pump is a pump capable of simultaneously treating gas and liquid, and the pump for compressing the LNG and the booster pump may be provided with a plurality of pumps in parallel.

The fuel supply system of the present invention includes a BOG supply line and an LNG supply line to supply BOG or LNG as fuel to the engine while an evaporative gas compressor for compressing the evaporation gas is provided in the BOG supply line, After that, the compressed evaporated gas is further boosted by a pump and supplied to the engine.

In place of the expensive high-pressure compressor, the evaporation gas compressed by the compressor is boosted by the pump to reduce the system installation cost, reduce the system operation cost by reducing the electricity consumption, and realize the compact system by reducing the footprint of the equipment . By configuring the system with an oil-free sealed compressor, pollutants from equipment can be reduced.

Further, it is possible to simplify the design of the fuel supply system by configuring the evaporating gas generated when the LNG is pumped or the boosted evaporating gas exceeding the required amount of the engine fuel to be introduced into the common re-liquefaction unit.

1 schematically shows a fuel supply system according to a first embodiment of the present invention.
Fig. 2 schematically shows a 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 according to a first embodiment of the present invention.

In the system of FIG. 1, the boil off gas generated in the storage tank T of the ship or the sea structure is supplied to the compressor 10 through the first line L1 to compress the compressed BOG, Liquefied in the system (20) and transferred to the storage tank (T).

Since the BOG to be introduced into the liquefaction system is compressed to 45 to 320 bar, the compressor can be configured in multiple stages, and the BOG through a part of the multi - stage compressors can be branched as needed, ) Or GCU (Gas Combustion Unit).

The main engine of the ship or the offshore structure is supplied with fuel via the second line (L2) from the storage tank (T) to the pump (P). The second line is provided with a high-pressure pump 30 for compressing the pumped LNG according to the required pressure of the main engine. If the main engine is an ME-GI (Man Electric Gas Injection) engine, for example, To 150 to 400 bar.

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 a cryogenic storage tank (T), and use natural gas as the fuel. Depending on the load A gas supply pressure of about 150-400 bara (absolute pressure) is required. Compared with a diesel engine of the same output, pollutant emissions can be reduced by 23% of carbon dioxide, 80% of nitrogen compounds and 95% of sulfur compounds It is attracting attention as a next-generation eco-friendly engine.

In this embodiment and a second embodiment to be described later, such an ME-GI engine can be applied to a ship or a marine structure engine.

The LNG compressed in the high-pressure pump 30 is supplied to the fuel of the main engine via the vaporizer 40. [ Since LNG compressed at high pressure is in a supercritical state, the phase change does not occur in the vaporizer, and heat energy is supplied through the vaporizer.

On the other hand, some of the evaporated gas passing through the re-liquefaction system may be supplied to the main engine through the high-pressure pump through the recondenser 50.

According to the first embodiment, the LNG can be supplied to the main engine and the BOG can be re-liquefied to supply some of the re-liquefied BOG as the fuel for the main engine. However, such a system has the advantage of being able to supply LNG and BOG more effectively as fuel than before, but still consumes much electricity in the compressor to compress the BOG. Such a high-pressure compressor has a high weight and volume, low space utilization, and high installation cost. The second embodiment of the present invention shown in Fig. 2 solves this problem and proposes a more effective and economical fuel supply system.

2, in the fuel supply system of a ship or an offshore structure, a fuel supply system of a second embodiment is characterized in that a boil-off gas generated in a storage tank T of a ship or a marine structure is supplied to a ship A LNG supply line LL for supplying LNG stored in a storage tank T of a ship or a marine structure as fuel to the engine and a BOG supply line BL for supplying the engine as a fuel, BL, and the evaporation gas compressor 100 compresses the evaporation gas. The evaporation gas is compressed to a medium pressure in the evaporation gas compressor 100 and then further boosted and supplied to the engine.

The present embodiment further includes a booster pump 200 provided in the BOG supply line BL for boosting the evaporation gas, and the re-condenser 300 for re-liquefying the evaporated gas boosted by the booster pump 200 is connected to the re- (RL).

That is, the evaporated gas passing through the evaporative gas compressor 100 and the booster pump 200 may be supplied as fuel to the engine, and the evaporated gas exceeding the fuel required amount of the engine may be supplied to the re-condenser 300 To be re-liquefied.

Through the evaporative gas compressor 100, the evaporation gas is compressed to a medium pressure of 3 to 10 bar, preferably 6.5 bar, and the booster pump 200 supplies the evaporation gas at 30 to 500 bar, preferably 150 to 400 bar You can boost.

The re-liquefied evaporated gas passing through the remanufacturing unit 300 is supplied to and stored in the storage tank T or supplied to the front end of the LNG supply line LL if necessary.

At the front end of the LNG supply line LL, the interconnecting lines connected to the booster pump 200 are branched, and the evaporated gas re-liquefied through the interconnecting lines is reintroduced into the booster pump 200.

The booster gas introduced through the interconnecting line may be a mixture of gas and liquid. For this purpose, the booster pump 200 is provided with a pump capable of simultaneously treating gas and liquid. For example, a Haskel pump Can be applied.

The LNG supply line LL is provided with a boosting pump 400 for compressing the LNG and a vaporizer 500 for vaporizing the LNG compressed by the boosting pump 400, The interconnecting line connected to the booster pump 200 is branched from the LNG supply line LL.

The gas line VL connected from the rear end of the boosting pump 400 to the rear end of the booster pump 200 is branched from the LNG supply line LL and is generated when the LNG is pumped from the boosting pump 400 The evaporated gas is supplied to the remanufacturing unit 300 through the gas line VL.

In the LNG supply line LL, a first shut-off valve 600 is provided at the front end of the boosting pump 400, and a second shut-off valve 700 is provided at the interconnecting line. The booster pump 400 is provided with a pump dedicated to the liquid and is connected to the booster pump 400 through the first shutoff valve 600 when the evaporated gas passing through the re-fluidizer 300 is supplied to the LNG supply line LL The LNG supply line LL is cut off and the evaporation gas is introduced into the booster pump 200 through the interconnecting line.

In the case of a marine structure or a ship equipped with an ME-GI engine that pumps and energizes LNG and consumes it as a fuel, if the boil off gas (BOG) generated in the LNG storage tank (T) , A gas-combus- tion unit (GCU), an auxiliary engine, etc., to process the BOG. However, the present embodiment can selectively supply BOG and LNG as fuel, thereby reducing the amount of waste BOG, Fuel supply is possible. The ship of this embodiment may be provided with one or more ME-GI engines.

Meanwhile, the booster pump 200 and the booster pump 400 may be provided with a plurality of pumps in parallel. The booster pump 200 capable of simultaneously treating the gas and the liquid has a relatively small capacity of the pump, so that a plurality of pumps can be installed in parallel to increase the processing capacity.

The evaporative gas compressor 100 may be a compressor sealed in an oil-free type including a centrifugal compressor, a screw compressor, and a reciprocating compressor, Compressor.

If there is a large amount of evaporative gas, the evaporative gas can be supplied to a sub - engine, a GCU, and an inert gas generator (IGG) through a line BL2.

According to another aspect of the present invention, there is provided a liquefied natural gas (LNG) system comprising: 1) an LNG stored in a storage tank (T) of a ship or an offshore structure,

2) The boil-off gas generated in the storage tank T is compressed by the compressor to a medium pressure, then is boosted to the booster pump 200 and supplied to the engine,

The evaporation gas raised in the booster pump 200 or the evaporation gas generated in the pumping of the LNG is re-liquefied and then stored in the storage tank T or boosted by the booster pump 200 to be supplied to the engine A fuel supply method is provided.

As described above, in the fuel supply system of the present invention, instead of an expensive high-pressure compressor, the evaporation gas compressed by the compressor is boosted by the pump, thereby reducing the installation cost of the system, . In addition, by using a universal compressor instead of a heavy and bulky high-pressure compressor, a compact system can be realized by reducing the footprint of the equipment. By configuring the system with an oil-free sealed compressor, pollutants from equipment can be reduced.

Further, the evaporating gas generated when the LNG is pumped or the heated evaporated gas exceeding the required amount of the engine fuel is introduced into the common remanufacturing unit 300 to be re-liquefied and supplied to the storage tank T, To be supplied. This makes it possible to simplify the fuel supply system design by not requiring a line for the treatment of the evaporative gas generated during the LNG pumping or a line for the treatment of the evaporative gas exceeding the fuel requirement.

Both the LNG and the BOG can be supplied as the fuel of the engine, so that efficient fuel supply can be achieved and the amount of waste BOG can be reduced by burning.

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.

T: Storage tank
P: Pump for supplying LNG
BL: BOG supply line
LL: LNG supply line
RL: Re-liquefaction line
VL: Gas line
100: Evaporative gas compressor
200: Booster pump
300: Re-
400: Boosting pump
500: vaporizer
600: first shut-off valve
700: Second shutoff valve

Claims (10)

In a fuel supply system for a ship or an offshore structure,
A BOG supply line for supplying boil-off gas generated from the storage tank of the ship or the offshore structure to the engine of the ship or the offshore structure as fuel;
An LNG supply line for supplying the engine with stored LNG from a storage tank of the ship or an offshore structure;
An evaporative gas compressor provided in the BOG supply line for compressing the evaporative gas;
A booster pump provided in the BOG supply line to boost the evaporation gas;
A re-culling unit for re-liquefying the evaporated gas boosted by the booster pump;
A redistribution line provided with the redistribution unit;
A booster pump provided in the LNG supply line and compressing the LNG; And
And an interconnect line branched from the LNG supply line and connected to the booster pump at a front end of the boosting pump,
The evaporation gas is compressed to a medium pressure in the evaporative gas compressor and then further boosted by the booster pump and supplied to the engine,
The booster pump is a pump capable of simultaneously treating gas and liquid,
And the evaporated gas that has passed through the re-culling unit is supplied to the front end of the storage tank or the LNG supply line. delete delete delete The method according to claim 1,
A vaporizer provided in the LNG supply line for vaporizing the LNG compressed by the boosting pump; And
And a gas line branched from the LNG supply line at a rear end of the booster pump and connected to a rear end of the booster pump,
And the evaporating gas generated in the booster pump is supplied to the re-culling unit through the gas line. The method according to claim 1,
A first shut-off valve provided at a front end of the boosting pump in the LNG supply line; And
And a second shut-off valve provided on the interconnect line,
And the LNG supply line connected to the booster pump through the first shutoff valve is shut off when the evaporative gas that has passed through the re-culling unit is supplied to the LNG supply line. The method according to claim 1,
Wherein the booster pump and the boosting pump are provided with a plurality of pumps in parallel. The method according to claim 1,
Characterized in that the evaporative gas compressor is a compressor sealed in an oil-free type including a centrifugal compressor, a screw compressor and a reciprocating compressor. system. delete delete

Images