Fuel gas supply system and method of a ship

TECHNICAL FIELD The present invention relates to a system and method for supplying gas fuel on a ship, and in particular to a system and method of supplying gaseous fuel on a vessel for efficiently delivering gaseous fuel from an LNG (liquefied natural gas) tank to a high pressure gas injection engine. a ship that is not a gas tanker

LNG.

Background Art [0002] In general, natural gas is transformed into liquefied natural gas (hereinafter "LNG") at cryogenic temperature in a liquefaction plant, and then transported over long distances to its destination by the LNG transport.

[0003] Since liquefaction of natural gas occurs at a cryogenic temperature of -163 degrees Celsius at ambient pressure, LNG can be evaporated, even when the LNG temperature is only slightly higher than -163 degrees Celsius at ambient pressure. In an LNG transporter with an LNG tank that is thermally insulated, since heat is permanently transferred from the outside to the LNG in the LNG tank, LNG is constantly evaporated and an evaporation gas is produced in the LNG tank during LNG transport by the LNG transport.

[0004] In an LNG transporter, if the evaporation gas is collected in the LNG tank, the pressure in the LNG tank increases excessively. Consequently, to use the evaporation gas produced in the LNG tank, the evaporation gas is used as a fuel for the ship's propulsion engine or it is burned in the gas combustion chamber.

[0005] In the case where a motor with a high pressure gas injection is used as the propulsion engine of a LNG gas carrier, for example, a MEGI engine manufactured by MAN

B & W Diesel, Inc., a conventional multi-stage compressor is used in a conventional gas fuel system to compress the high pressure evaporative gas. This multistage compression creates problems because the gas fuel system becomes very complicated and an excessive amount of energy is required to pressurize the gas in a gaseous state to a high pressure. The provision of gaseous fuel on an LNG carrier is known from EP 1990272 of the prior art. In addition, it is known from WO 97/32157 to supply fuel to the engine.

[0006] Vessels such as bulk carrier, container ship, oil tanker and chemical tanker can be driven using LNG as a fuel. Such vessels have an LNG fuel tank for LNG storage as a fuel and use the same engine as the LNG transport.

DISCLOSURE OF THE INVENTION [0007] According to an embodiment of the invention, there is provided a gas fuel supply system on a ship comprising a device according to claim 1.

[0008] Preferably, the gasifying device comprises a heater.

[0009] Preferably, the high pressure pump compresses the LNG with approximately 100 to 300 bar manometric pressure, and then delivers a compressed LNG to the high pressure gas injection engine.

[0010] Preferably, the evaporation gas is in thermal connection with the LNG to minimize the capacity of the evaporation gas condensing unit.

[0011] According to an embodiment of the invention, there is provided a method of delivering gaseous fuel to the engine of a high pressure gas injection vessel as defined in claim 5.

[0012] Preferably, the LNG pressure for the high pressure gas injection engine is in the range of about 100 bar to about 300 bar manometric pressure.

[0013] Preferably, the evaporation gas exchanges heat with LNG, improving the re-condensation efficiency.

According to a further embodiment of the invention, there is provided a gas fuel supply system on a vessel for supplying gaseous fuel on a motor ship with a high pressure gas injection, and the gaseous fuel supply system comprises:

LNG tank, gas fuel feed line connecting the LNG tank on the ship with the engine with high pressure gas injection;

LNG compression means installed in the gas fuel supply line between the LNG tank and the engine with high-pressure gas injection; and LNG gasification means installed in the gas fuel feed line behind the compression means to gasify the compressed LNG.

[0015] Preferably, the prestressing means are configured to take the LNG from the LNG tank, compress the LNG collected to high pressure and supply the compressed LNG towards the motor with a high pressure gas injection.

[0016] Preferably, the prestressing means comprise one pump.

[0017] Preferably, the prestressing means further comprise a second pump.

[0018] Preferably, the gas fuel supply system further comprises:

a heat exchanger installed downstream of the first pump in the gas fuel feed conduit and the evaporation gas condensing conduit connecting the upper LNG tank passing through the heat exchanger to one side of the LPG tank, the gas condensation conduit configured to liquefy the evaporation gas created in the LNG tank.

[0019] Preferably, the gas fuel supply system further comprises:

a heat exchanger installed between one pump and another pump in the gas fuel supply line; and a condensation gas conduit, passing from the upper part of the LNG vessel through a heat exchanger and connecting the heat exchanger with the gasifying means.

[0020] Preferably, the gaseous fuel supply system further comprises:

a recondenser installed after the first pump in the gas fuel supply line; and a condensation gas conduit passing through the reconder, connecting the upper part of the LNG tank and the LNG tank.

[0021] Preferably, the radiator is a gasifier.

[0022] Preferably, the LNG is taken from the LNG tank and then compressed approximately from 20 to 300 bar manometric pressure [0023] Preferably, the LNG tank is designed to withstand a pressure increase due to the evaporation gas so as to allow the pressure increase caused by the the evaporation gas produced in the LNG tank during the voyage of the ship.

[0024] Preferably, the ship is an LNG transporter and the LNG tank is an LNG storage tank.

[0025] Preferably, the ship is a ship such as a bulk carrier, container ship, oil tanker and chemical transporter, and the LNG tank is a LNG fuel tank for storing LNG as a fuel.

[0026] According to a further aspect of the invention there is provided a method of feeding a gaseous liquefied natural gas (LNG) fuel gas for supplying gaseous fuel on a ship to a high pressure gas injection engine comprising:

taking LNG from the LNG tank of the ship, compressing the collected LNG to meet the pressure requirements for the engine with high-pressure gas injection;

gasification of compressed LNG; and supplying gasified LNG to the engine with high pressure gas injection.

0027] Preferably, the method further comprises:

taking the evaporation gas from the LNG tank; and heat exchange between LNG and the evaporation gas before LNG gas is delivered to the engine with high pressure gas injection.

[0028] Preferably, the method further comprises: condensation of the evaporation gas; and returning the liquefied vaporization gas to the LNG tank.

[0029] Preferably, the method further comprises:

increasing the LNG temperature by exchanging heat between LNG and the evaporation gas before supplying LNG to the engine with high pressure gas injection;

condensation of the evaporation gas; and providing liquefied vaporization gas to a high pressure gas injection engine.

[0030] Preferably, the method further comprises:

mixing LNG with evaporation gas from the LNG tank; and providing a mixture of LNG and a vaporization gas to a high pressure gas injection engine.

Preferably, LNG is gasified by heating.

[0032] Preferably, the method further comprises:

allowing the pressure to increase due to the evaporation gas generated in the LNG vessel during the voyage of the vessel.

[0033] Preferably, the LNG pressure for the high pressure gas injection engine is in the range of about 20 bar to about 300 bar manometric pressure.

[0034] In order to solve some of the above or other problems associated with the prior art, the present invention inter alia aims to provide a method and a gas fuel supply system on a ship that can simplify configuration, reduce power demand and prevent excessive pressure buildup in the LNG tank due to the accumulation of evaporation gas, when delivering gas fuel to the engine with high-pressure gas injection.

[0035] In order to achieve the abovementioned objectives, the gas fuel supply system on a ship according to one embodiment of the present invention, as a system for supplying gas fuel to a high pressure gas engine on a ship is characterized in that the LNG is taken from the LNG vessel of the ship, compressed for high pressure, gasified and then supplied to the engine with high-pressure gas injection.

[0036] Furthermore, the method of supplying gaseous fuel on a ship according to an embodiment of the present invention as a method for providing onboard gas fuel to a high pressure gas injection engine is characterized in that the LNG is taken from the LNG vessel of the ship, compressed to meet pressure requirements for a high-pressure gas injection engine, gasified and then supplied to a high-pressure gas injection engine.

BRIEF DESCRIPTION OF SEVERAL VIEWS IN DRAWINGS [0037]

Figure 1 is a schematic view of a gas fuel supply system 5 on a ship, except for an LNG transporter, according to an embodiment of the present invention,

Figure 2 is a schematic view of a gas fuel supply system on a ship, with the exception of an LNG transporter, according to another aspect of the present invention and

Figure 3 is a schematic view of a gas fuel supply system on a ship, with the exception of an LNG transporter, according to yet another aspect of the present invention.

DETAILED DESCRIPTION [0038] Preferred embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0039] Figure 1 is a schematic view of a gas fuel supply system on a ship according to an aspect of the present invention. As shown in Figure 1, the gas fuel supply system on the ship is intended to supply gaseous fuel to a high pressure gas injection engine on a ship that is not an LNG transporter.

[0040] The gas fuel supply system of Figure 1 includes a L1 fuel feed line for delivering LNG taken from the LNG vessel 1 to a high pressure gas engine on the ship and a heat exchanger 3 mounted in the central portion of the L1 fuel line so that it flows heat exchange between LNG and the evaporation gas taken from the LNG 1 tank.

[0041] The ship may be an LNG transport. The LNG transporter has an LNG tank for LNG storage. In this case, the LNG 1 tank is an LNG storage tank.

[0042] Furthermore, the ship may be a ship such as a bulk carrier, a container ship, an oil tanker and a chemical transporter that can be driven by LNG fuel. Such a ship has an LNG fuel tank for storing LNG as a fuel. In this case, the LNG 1 tank is an LNG fuel tank for storing LNG as a fuel.

[0043] The L1 fuel feed line has a first pump 2 for compressing the LNG in front of the heat exchanger 3 to meet pressure requirements for the high pressure gas engine and supply LNG towards the high pressure gas injection engine. According to this embodiment of the invention, the first pump 2 is shown installed in the LNG 1 tank, but can be installed in the supply line L1 with gas fuel in front of the heat exchanger 3 outside the LNG tank 1. Furthermore, the first pump 2 can comprise one pump or two pumps.

[0044] The evaporation liquefaction conduit L2 is connected from the upper part of the LNG 1, passing through the heat exchanger 3, to one side of the LNG 1 tank. The evaporation gas is withdrawn from the upper part of the LNG 1, flows through the heat exchanger 3 and is recycled one side of the LNG 1 tank.

In the heat exchanger 3, the LNG heat is exchanged with the evaporation gas heat to raise the LNG temperature, and then the LNG is supplied towards the high pressure gas engine and the evaporation gas is condensed by heat exchange with the LNG and then recycled back to the LNG. 1. If the evaporation gas in the upper part of the LNG 1 tank is condensed and returned to the lower part of the LNG 1 tank, it may prevent excessive pressure in the LNG 1 tank caused by the accumulation of the evaporation gas in the LNG 1 tank.

[0046] In one embodiment of the present invention, the second pump 4 is installed in the supply line L1 with the gaseous fuel downstream of the heat exchanger 3 so as to compress the LNG which exchanged heat with the evaporation gas to meet the pressure requirements for the high pressure gas injection engine, and then deliver the compressed LNG to the engine with high pressure gas injection.

The heater 5 is installed in the gas supply line L1 behind the second pump 4 in such a way as to heat the LNG, which exchanged heat in the heat exchanger 3, and then supply LNG, which exchanged heat to the high-pressure gas injection engine.

[0048] In one embodiment of the invention, the compressor 6 and the evaporation gas cooler 7 are installed in the evaporation liquefaction conduit L2 in front of the heat exchanger 3 so as to compress and cool the evaporation gas drawn from the LNG 1 before the heat exchange between the evaporation gas and the LNG .

[0049] In case the engine with high pressure gas injection is, for example, a MEGI engine manufactured and sold by MAN B & W Diesel Inc., the required gas fuel pressure for the MEGI engine can be from 200 to 300 bar (manometric pressure), more preferably 250 bars (gauge pressure). The LNG is compressed to 27 bar (gauge pressure) by the first pump 2 and the LNG temperature increases by passing through the heat exchanger 3 from about -163 degrees Celsius to approximately -100 degrees Celsius, and the LNG in the liquid state is supplied and compressed in the second pump 4 up to about 250 bar (gauge pressure) (as it is in a supercritical state, there is no separation between liquid and gaseous states), then heated in a heater 5 and then supplied to the engine with high pressure gas injection.

[0050] On the other hand, in the case where the high pressure gas injection engine is, for example, a gas turbine engine, the required gas fuel pressure for the gas turbine engine may be in the range of 20 to 40 bar (gauge pressure) preferably 30 bar (manometric pressure). The LNG in the first pump 2 is compressed to 30 bar (manometric pressure) and a part of the LNG is gasified as it passes through the heat exchanger 3 supplied to the heater 5 and heated in the heater 5 and then supplied to the high pressure gas injection engine. In this case, the second pump 4 is not necessary.

The pressure-regulating pressure regulating valves 11 are arranged in the supply line L1 by the gaseous fuel at the front and rear of the first pump 2, in the feed line L1 by the gaseous fuel, at the front and rear of the second pump 4 and at the evaporation liquefaction gas L2 at the front and on the back of the gas compressor 6 and cooler 7 so as to control the pressure of the fluid flowing through the conduits.

Furthermore, the temperature-regulating flow control valves 12 are installed in the feed line L1 of the gaseous fuel, on the front and back of the heater 5 in such a way as to control the temperature of the fluid flowing through the conduit.

The pressure sensors 13 are connected between the pressure regulating valves 11 and the gas supply line L1 at the rear end of the first pump 2, the fuel feed L1 at the rear end of the second pump 4 and the evaporation liquor L2 at the rear end of the compressor 6 the evaporation gas and cooler 7. Also, the temperature sensors are connected between the L1 power line and the gas fuel at the rear end of the heater 5, and the temperature regulating valves 12.

The pressure-regulating pressure regulating valves 11 and the temperature-regulating valves 12 regulate the flow rate, thereby controlling the pressure or temperature of the fluid passing therethrough.

[0055] Furthermore, in the central part of the evaporation liquefaction conduit L2, after the heat exchanger 3, a relief pressure regulating valve 12a is mounted so as to control the pressure of the fluid flowing through the conduit L2.

[0056] The pressure sensor 13 is connected between the pressure control valve 12a and the supply line L2 with the gaseous fuel at the front end of the pressure control valve 12a installed in the evaporation gas condensing fluid L2 after the heat exchanger 3.

The pressure regulating valve 12a installed in the evaporation liquefaction conduit L2 after the heat exchanger 3 expands the flowing fluid in such a way that the pressure corresponds to that obtained by adding pressure in the LNG 1 to the pressure caused by the LNG hydrostatic pressure in the LNG 1 tank , thus controlling the decreasing, by decompression, pressure and LNG temperature.

[0058] In one embodiment of the invention, as shown in

2, the evaporation liquefaction conduit L2 may be configured to pass through the heat exchanger 3 from the upper part of the LNG 1 and is connected between the heat exchanger 3 and the heater 5 in the central part of the L1 power line with gaseous fuel. According to this configuration, the evaporation gas is condensed by exchanging heat with LNG in a heat exchanger 3, compressed in a liquid state, gasified, and then used as a gaseous fuel for a high-pressure gas injection engine. In this case, the pressure-regulating valve 12a installed in the evaporation liquefaction conduit L2 after the heat exchanger 3 regulates the pressure of the passing fluid to correspond to the LNG pressure in the L1 feed line with the gaseous fuel.

[0059] According to the above-mentioned embodiment of the invention, the heat exchanger 3 for the heat exchange between the LNG and the evaporation gas taken from the LNG 1 is mounted in the middle part of the L1 feed line with gaseous fuel. However, instead of the heat exchanger 3, a recondenser can be mounted for direct mixing of the LNG and the evaporation gas. According to the embodiment of the invention shown in Figure 3, the recondenser 103 is mounted in the supply line L1 instead of the heat exchanger with a gaseous fuel. The evaporation liquefaction conduit L2, which draws the vaporization gas from the upper part of the LNG 1 tank and recirculates the evacuation gas to one side of the LNG 1, passes through a recondenser 103 mounted in the middle part of the L1 power line with gaseous fuel.

[0060] Also, according to the present invention, in a fuel gas supply system on a ship, produced in a tank

LNG, the evaporation gas is not compressed in the gaseous state to high pressure, and therefore it is not used as fuel for the engine with high-pressure gas injection.

[0061] Furthermore, the LNG tank used in a fuel gas fueling system on a ship, according to an embodiment of the present invention, may be designed to have sufficient strength to withstand the pressure increase caused by the evaporation gas so as to allow the pressure increase caused by the evaporation gas produced in the LNG tank during the voyage of the ship.

[0062] Furthermore, the gas fuel supply system on a ship, according to an embodiment of the present invention, may include a "cold box" evaporation condensation plant (comprising a plate cryogenic heat exchanger and an aggregate separator into one closed insulated assembly) and a cooling system. The heat exchanger is mounted in the middle part of the gas fuel feed line for LNG compression in the LNG tank and for supplying compressed LNG as gas fuel to the high pressure gas engine, and the gas fuel produced in the LNG tank exchanges heat from the LNG in the middle part of the power line by evaporation gas, and therefore is liquefied. Consequently, the evaporation gas condensation device, which is additionally mounted, can be configured to have a small capacity.

[0063] As is apparent from the above, according to the present invention, in a gas fuel supply arrangement and method on a ship, LNG is taken from the LNG tank, compressed to high pressure, gasified and fed to a high pressure gas injection engine. Consequently, the gas fuel system and method has advantages - simplifying configuration, reducing energy demand and preventing excessive pressure increase due to the accumulation of the evaporation gas in the LNG tank when supplying gaseous fuel to the engine of a vessel with high pressure gas injection.

[0064] Although the present invention has been described herein and described with reference to particular embodiments of the invention, it should be understood that various modifications, variations and corrections may be made to those skilled in the art, and thus the present description and drawings should be construed as illustrative without limiting the scope defined in the claims.

Daewoo Shipbuilding & Marine Engineering Co., Ltd.

Proxy:

77P38311PL00

EP 2 447 593 B1