KR20180087017A - Fuel Supply System and Method for LNG Fueled Vessel - Google Patents

Abstract

The present invention relates to a liquefied natural gas fuel vessel capable of supplying fuel in accordance with fuel supply conditions of an engine using a pump and a regeneration facility without using a compressor in a ship to which an engine using liquefied natural gas as fuel is applied, And more particularly, to a fuel supply system and method for a fuel cell.
The fuel supply system for a liquefied natural gas fuel vessel according to the present invention comprises an autocycle engine which operates with Otto Cycle using liquefied natural gas as fuel; A fuel supply pump for discharging liquefied natural gas from the storage tank; A high pressure pump for compressing the discharged liquefied natural gas; A vaporizer for vaporizing the liquefied natural gas compressed by the high-pressure pump; An expansion valve for swelling the natural gas vaporized in the vaporizer; And a gas-liquid separator for gas-liquid separating the gas-liquid mixture formed by the expansion valve, wherein the liquid separated from the gas-liquid separator is recovered to the storage tank, and the gas separated from the gas- And the methane value of the natural gas fuel supplied to the autocycle engine is controlled.

Description

Technical Field [0001] The present invention relates to a fuel supply system and method for a liquefied natural gas fuel vessel,

The present invention relates to a liquefied natural gas which can supply liquefied natural gas fuel in accordance with fuel supply conditions of an engine using a pump and a regeneration facility without using a compressor in a ship to which an engine using liquefied natural gas as fuel is applied, To a fuel supply system and method for a gas-fueled vessel.

Generally, a ship is propelled by an engine that generates power by combustion of fuel. Fuel oil such as light oil, heavy oil, and MDO (Marine Diesel Oil) used as a fuel of a ship is a large quantity It is a cause of environmental pollution due to harmful substances. Recently, as international regulations to prevent air pollution have been strengthened, the fuel of ships is changing from fuel oil to natural gas. Natural gas is relatively environmentally friendly because it has a low sulfur content and does not generate sulfur compounds and sooty materials during combustion. In response to this trend, a dual-fuel engine has been developed that can use natural gas with fuel oil.

On the other hand, since natural gas is in a gaseous state at room temperature and atmospheric pressure, its volume is so large that space for storage is limited. Therefore, natural gas is usually treated with a heat insulating material by keeping the liquid state at an extremely low temperature of about -163 ° C at normal pressure Cryogenic LNG can be stored in a special storage tank at normal pressure.

In addition, Liquefied Fueled Ship (LFS), which uses liquefied natural gas (LNG) as a fuel, has been developed as an environmentally friendly ship (green ship) and has been granted Approval Approval Principle (AIP) And it meets the requirement to convert to clean energy due to environmental regulations. Such LFS is being developed not only for LNG carriers that transport LNG as cargo but also for commercial vessels including container ships and tanker ships.

Generally, among engines used in ships, there are MEGI engine and DF (Dual Fuel) engine that can use natural gas as fuel.

The ME-GI engine consists of two strokes and employs a diesel cycle in which high pressure natural gas at around 300 bar is injected directly into the combustion chamber at the top of the piston.

The diesel cycle follows a constant pressure process in which the combustion at the top dead center is constant. During the up stroke, only the combustion air is sucked into the cylinder, and the sucked combustion air is adiabatically compressed at a high compression ratio. When reaching the top dead center, the combustion air reaches a considerably high temperature due to the adiabatic compression during the compression stroke. When the fuel is injected into the adiabatically compressed combustion air, the temperature is spontaneously ignited due to the high temperature.

The combustion pressure of the fuel at the top dead center is adjusted by adjusting the injection pressure of the fuel appropriately in order to prevent the pressure from being higher due to the explosion due to the fuel injection even though the combustion air which has reached the top dead center in the diesel cycle is already high pressure .

The higher the compression ratio of the diesel engine is, the more the combustion efficiency is increased. However, the fuel is compressed at a compression ratio of about 15 to 22: 1 in consideration of the explosion pressure.

Further, since only the air is compressed in the compression stroke of the diesel engine, knocking, which is a phenomenon that premature ignition occurs before the piston reaches the top dead center, does not occur originally.

The DF engine adopts the Otto Cycle which consists of four strokes or two strokes and injects natural gas having a relatively low pressure of 6.5 bar or 18 bar into the combustion air inlet to compress the piston as it rises .

The autocycle follows a static process with a constant volume when the combustion takes place near the top dead center. A mixture of the fuel and the combustion air flows into the cylinder before the rising stroke and is compressed together. The mixture introduced into the cylinder is adiabatically compressed and the temperature is raised. Premixing may occur if the mixer reaches too high a temperature. Therefore, the compression ratio of the autocycle is set lower than the diesel cycle.

Since the compression ratio of the autocycle is set relatively low, it is necessary to reach a high pressure when the fuel explodes by the ignition source at the top dead center. Explosion of the fuel within a short time as possible helps to improve the efficiency of the engine.

The engine following the autocycle injects the mixture of the fuel and the combustion air into the cylinder before the rising stroke so that premature ignition may occur before ignition by the ignition source and knocking may occur.

If the knocking phenomenon occurs, the efficiency of the engine may be lowered and damage to the engine may be caused. Therefore, it is important that the engine following the autocycle is operated to prevent the knocking phenomenon.

The anti-knocking performance in which the fuel used in the engine following the auto-cycle is not prematurely ignited is determined by the octane number in the case of the liquid fuel and by the methane number in the case of the gaseous fuel , And in the case of DF engines methane is required to be 80 or more.

In the case of the DF engine following the autocycle, the efficiency is lower than that of the ME-GI engine following the diesel cycle. However, since the combustion temperature of the fuel is not high and the amount of nitrogen oxide (NO _x ) And IMO Tier III, which is the regulation of nitrogen oxides in the environment.

Thus, in order to supply the LNG stored in the storage tank according to the specifications required by the engine, it is necessary to configure various equipments and a fuel supply system considering characteristics of the LNG and each engine.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing a fuel supply system of a conventional LNG carrier. FIG.

1, the conventional fuel supply system uses the evaporation gas supply system for supplying the evaporation gas discharged from the storage tank T to the engines E1 and E2 and the fuel for the engines E1 and E2, A re-liquefaction system for re-liquefying excess surplus gas, and a liquefied natural gas supply system for supplying liquefied natural gas inside the storage tank T to the engines E1 and E2.

The evaporative gas supply system includes a multi-stage compressor 200 and the liquefied natural gas supply system includes a first pump 610, a second pump 620, a vaporizer 700, a first heater 810, The redistribution system includes a first heat exchanger (110), a first decompressor (410), and a gas-liquid separator (500).

The multi-stage compressor 200 compresses the evaporated gas discharged from the storage tank T in a multistage manner and is provided with a plurality of compressing units 210, 220, 230, 240, and 250, A plurality of compressors 310, 320, 330, 340, 350 are used. In general, a multistage compressor for compressing the evaporative gas in five stages by five compressors and five compressors is used.

In addition, the multi-stage compressor 200 may include one or a plurality of branch lines, and the branch line is supplied again to the compression section through the compressed and evaporated gas, so that the pressure of the evaporation gas passing through the multi- And the flow rate. For example, as shown in FIG. 1, the branch line includes a first branch line L1 for branching the evaporation gas at the downstream end of the first compression section 210 and supplying it to the front end of the first compression section 210, And a second branch line L2 for branching the evaporation gas at the downstream end of the compression unit 250 and supplying the branched gas to the front end of the fourth compression unit 240.

The evaporated gas compressed through all the steps of the multi-stage compressor 200 is sent to the first engine E1, the evaporated gas compressed through only a part of the steps of the multi-stage compressor 200 is branched in the middle (L3 line) And sent to the engine E2. The first engine E1 may be an ME-GI engine and the second engine E2 may be a power generation DF engine.

The first pump 610 is installed inside the storage tank T to discharge the liquefied natural gas stored in the storage tank T and the second pump 620 is disposed in the storage tank T by the first pump 610. [ And compresses the liquefied natural gas discharged from the engine T to the required pressure of the first engine E1.

The vaporizer (700) forcibly vaporizes the liquefied natural gas compressed by the second pump (620). Some of the natural gas forced to be vaporized by the vaporizer 700 is supplied to the first engine E1 and the rest is supplied to the first heater 810.

The first heater 810 heats the natural gas vaporized by the vaporizer 700 to a temperature required by the second engine E2 and the second decompressor 420 heats the natural gas vaporized by the vaporizer 700 by the first heater 810 And pressurizes the heated natural gas to a pressure required by the second engine E2.

1 shows a first heater 810 installed at a rear end of the vaporizer 700 and a second decompressor 420 installed at a rear end of the first heater 810. The first heater 810 and the second heater 810, The second pressure reducing device 420 may be installed at the rear end of the vaporizer 700 and the first heater 810 may be installed at the rear end of the second pressure reducing device 420 .

The first heat exchanger 110 is cooled through all steps of the multi-stage compressor 200 and then cooled by partially exchanging the evaporated gas (L5 line) by heat exchange with the refrigerant discharged from the storage tank T . The surplus evaporated gas that is not supplied to the first engine E1 or the second engine E2 among the evaporated gases discharged from the storage tank T is supplied to the first heat exchanger 110 and is subjected to the liquefaction process will be.

The first pressure reducing device 410 expands the fluid (L5 line) cooled by the first heat exchanger 110 after being compressed by the multi-stage compressor 200. The evaporation gas that has undergone the compression process by the multi-stage compressor 200, the cooling process by the first heat exchanger 110, and the expansion process by the first decompressor 410 is partially or totally liquefied.

The gas-liquid separator 500 separates the re-liquefied liquefied natural gas passing through the multi-stage compressor 200, the first heat exchanger 110, and the first decompressor 410 and the evaporated gas remaining in the gaseous state . The liquid natural gas separated by the gas-liquid separator 500 is returned to the storage tank T and the gaseous vaporized gas separated by the gas-liquid separator 500 is mixed with the vaporized gas discharged from the storage tank T And is used as a refrigerant in the first heat exchanger (110).

When the second engine E2 is an engine following an auto-cycle such as a DF engine, the methane price of the natural gas supplied to the second engine E2 must be matched to prevent knocking. In the case of natural gas to be vaporized, the methane charge is lower than the natural vaporized vapor supplied by the vapor gas supply system.

According to the liquefied natural gas supply system, since the liquefied natural gas below the storage tank T is discharged by the first pump 610 installed under the storage tank T to be forcedly vaporized, the proportion of the component having a relatively high specific gravity is high Because.

Therefore, in particular, it is necessary to control the methane price of natural gas which is forcedly vaporized by a regeneration facility such as a vaporizer of a liquefied natural gas supply system. The present invention is applicable to a gasoline engine The present invention provides a fuel supply system and method for a liquefied natural gas fuel vessel capable of satisfying specifications of fuel gas.

According to an aspect of the present invention, there is provided an automatic cycle engine comprising liquefied natural gas as fuel and operating in accordance with an Otto Cycle; A fuel supply pump for discharging liquefied natural gas from the storage tank; A high pressure pump for compressing the discharged liquefied natural gas; A vaporizer for vaporizing the liquefied natural gas compressed by the high-pressure pump; An expansion valve for swelling the natural gas vaporized in the vaporizer; And a gas-liquid separator for gas-liquid separating the gas-liquid mixture formed by the expansion valve, wherein the liquid separated from the gas-liquid separator is recovered to the storage tank, and the gas separated from the gas- A fuel supply system for a liquefied natural gas fuel vessel that regulates the methane price of natural gas fuel supplied to the autocycle engine is provided.

Preferably, the system further comprises a liquefied natural gas cooler for heat-exchanging the liquefied natural gas compressed by the high-pressure pump and supplied to the vaporizer and the liquid separated from the gas-liquid separator and recovered into the storage tank, The compressed liquefied natural gas fed to the vaporizer can be heated and the liquid recovered in the storage tank cooled.

Preferably, the natural gas fuel heater further includes a fuel gas heater for heating the natural gas fuel separated from the gas-liquid separator and supplied to the fuel of the auto-cycle engine, wherein the natural gas fuel, which has passed through the expansion valve and the fuel gas heater, It can have the temperature required by the auto-cycle engine.

Preferably, the autocycle engine includes an X-DF engine as a two-stroke engine as a propulsion engine of the ship; And a DFDG (Dual Fuel Diesel Generator Engine) which is a 4-stroke engine as an auxiliary power production engine for the ship, and the natural gas fuel passed through the fuel gas heater is supplied to the X- Lt; RTI ID = 0.0 > pressure. ≪ / RTI >

Preferably, the system further includes a pressure reducing valve for reducing the pressure of the natural gas fuel to be supplied to the DFDG, wherein the natural gas fuel passing through the fuel gas heater and the pressure reducing valve may have a pressure required by the DFDG.

Preferably, the liquefied natural gas fuel line provides a path through which the liquefied natural gas is supplied to the engine from the storage tank through the high pressure pump and the vaporizer; And an evaporative gas fuel line for providing a path through which evaporative gas generated in the storage tank is supplied as fuel for the engine, wherein the evaporative gas fuel line includes: a compressor for compressing the evaporative gas; And an intermediate cooler for cooling the evaporated gas heated by compression in the compressor.

Preferably, the evaporative gas cooler further comprises a vaporized gas cooler for exchanging the compressed and cooled evaporated gas with the compressed liquefied natural gas supplied to the vaporizer, wherein the compressed liquefied natural gas supplied to the vaporizer is heated , The evaporation gas can be cooled.

Preferably, the evaporation gas expansion valve may expand the compressed evaporation gas cooled in the evaporation gas cooler to the same pressure as the vapor-liquid mixture supplied to the gas-liquid separator.

The apparatus may further include a GCU (Gas Combustion Unit) for processing the evaporative gas generated in the storage tank.

The control unit may control the temperature, the pressure and the flow rate of the fluid supplied to or discharged from the high-pressure pump, the vaporizer, the expansion valve, and the gas-liquid separator according to the load variation of the autocycle engine.

According to another aspect of the present invention, there is provided a method for controlling an internal combustion engine, comprising the steps of: 1) discharging liquefied natural gas stored in a storage tank to the outside using a fuel supply pump and compressing the liquefied natural gas using a high-pressure pump; 2) vaporizing the compressed liquefied natural gas using a vaporizer; 3) expanding the vaporized natural gas; 4) gas-liquid separation of the gas-liquid mixture formed by the expansion; And 5) supplying the gas-liquid separated liquid to the storage tank and supplying the gas-liquid separated gas to an autocycle engine that operates in accordance with an autocycle using liquefied natural gas as fuel, There is provided a fuel supplying method of a liquefied natural gas fuel vessel capable of supplying liquefied natural gas stored in a storage tank as fuel having a temperature, pressure and methane value required by the above-mentioned autocycle engine.

Preferably, (1-1) further comprises heat-exchanging the compressed liquefied natural gas with the liquid re-supplied to the storage tank in the step (5) before vaporizing the compressed liquefied natural gas in the step (2) The compressed liquefied natural gas may be heated by the liquid supplied to the storage tank and then vaporized, and the liquid re-supplied to the storage tank may be cooled by the compressed liquefied natural gas and then supplied to the storage tank.

Preferably, 5-1) heating the gaseous fuel supplied to the engine by gas-liquid separation in the step 5); And a control step of controlling the pressure, temperature and flow rate of the fluid in any one of the above steps according to a load variation of the auto-cycle engine, wherein the fluid passing through the step 5-1) And may have the pressure, temperature and methane required by the cycle engine.

Preferably, the method further comprises: 5-2) depressurizing the heated gaseous fuel, wherein the fluid having passed through the step 5-2) may have a pressure, a temperature and a methane value required by the autocycle engine .

Preferably, the evaporation gas generated in the storage tank is discharged and compressed in a compressor. And supplying the compressed vaporized gas to the fuel of the autocycle engine, wherein the compressed vaporized gas may have a pressure and a temperature required by the autocycle engine.

Preferably, the step of expanding the compressed evaporative gas may further include feeding the expanded evaporative gas into the fuel of the autocycle engine by joining the expanded evaporative gas to the step 4).

Preferably, the step of cooling the compressed evaporative gas by heat-exchanging the compressed evaporative gas with the compressed liquefied natural gas supplied to the evaporator in the step 2) As fuel.

According to the present invention, it is possible to supply the fuel that satisfies the fuel gas specification required by the auto-cycle engine. In particular, the operation cost can be reduced by using the high-pressure pump and the regeneration facility in comparison with the conventional method using the BOG compressor, The high-pressure pump and regenerator can reduce the installation area of the equipment and the cost of the installed equipment, rather than applying the BOG compressor.

Conventionally, even if a high-pressure pump and a regeneration unit are used, the methane price can not be set to the required level or higher in the case of an autocycle engine, but the methane price required by the engine can be secured.

In addition, since a part of the gas is re-liquefied and re-supplied to the storage tank, the amount of natural gas BOG can be minimized.

Further, according to the present invention, it is possible to supply the required flow rate of the fuel gas while maintaining the temperature and the pressure in accordance with the change, and in particular, to control the flow rate of the high- The pressure control allows the engine fuel demand temperature and pressure to remain constant with a flexible response to the engine load.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic view showing a fuel supply system of a conventional LNG carrier. FIG.
2 is a schematic view showing a fuel supply system of a liquefied natural gas fuel vessel according to an embodiment of the present invention.

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

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the drawings, like reference numerals refer to like elements throughout. The same elements are denoted by the same reference numerals even though they are shown in different drawings.

In the following examples, liquefied natural gas is taken as an example, but the present invention can be applied to various liquefied gases, and the following embodiments can be modified in various other forms, and the scope of the present invention is limited to the following embodiments It is not.

In the following embodiments, the fluid flowing through each channel may be in a gas state, a gas-liquid mixed state, a liquid state, or a supercritical fluid state, depending on the operating conditions of the system.

In the following embodiments, the vessel may be a liquefied natural gas carrier (LNG carrier) for transporting liquefied natural gas as a cargo, or may be a general merchant ship having a storage tank for storing liquefied natural gas, It can be applied to all ships that have liquefied natural gas as fuel and have propulsive power by engine or can produce electric power by driving engine.

2 is a schematic view showing a fuel supply system of a liquefied natural gas fuel vessel according to an embodiment of the present invention. Hereinafter, a fuel supply system and method of a liquefied natural gas fuel vessel according to an embodiment of the present invention will be described with reference to FIG.

As shown in FIG. 2, a fuel supply system for a liquefied natural gas fuel vessel according to an embodiment of the present invention includes liquefied natural gas stored in a storage tank 10 for storing liquefied natural gas, (LL) for supplying the natural gas fuel to the combustion engine.

The storage tank 10 for storing the liquefied natural gas of this embodiment is a membrane tank designed or built to store cryogenic natural gas at normal pressure or designed to store cryogenic liquefied natural gas at a relatively high pressure. It can be a type C tank to be manufactured, and can be selected according to installation position, capacity, and the like. However, the storage tank 10 of the present embodiment is preferably a membrane tank.

An engine supplied with liquefied natural gas fuel along the liquefied natural gas fuel line LL may be an auto-cycle engine (ME, GE) that applies an auto-cycle.

In the present embodiment, the auto-cycle engine is a two-stroke DFME (2-stroke Duel Fuel Main Engine), an X-DF engine (ME) and a 4-stroke DFDG (4-Stroke Dual Fuel Diesel Generator Engine (GE) can be used for ship auxiliary electric power generation (GE). X-DF engine (ME) and electric power generation engine (GE) have different specifications of natural gas supplied as fuel.

For example, in the present embodiment, the X-DF engine (ME) requires natural gas fuel having a temperature of about 18 barg, a temperature of about 0-60 ° C and a methane number of about 80 or greater, ) Requires natural gas fuels having a methane content of about 5 barg, about 0-60 < 0 > C and about 80 or more.

Therefore, in order to supply the liquefied natural gas fuel to the engines ME and GE while satisfying the fuel gas requirements of the engines ME and GE, the liquefied natural gas stored in the liquid state at the cryogenic temperature The gas must be heated and vaporized, compressed, and the methane content adjusted.

On the liquefied natural gas fuel line LL of the present embodiment, the liquefied natural gas stored in the storage tank 10 is supplied to the fuel (e.g., fuel) that meets the conditions of the fuel pressure, temperature, A fuel supply pump 11 for discharging liquefied natural gas from the storage tank 10, a high-pressure pump 20 for compressing the liquefied natural gas discharged by the fuel supply pump 11, a high- A vaporizer 30 for vaporizing the liquefied natural gas compressed by the evaporator 30 and an expansion valve 40 for expanding the natural gas vaporized in the vaporizer 30 and an expansion valve 40. The gas- Liquid separator 50 is provided.

The fuel supply pump 11 of the present embodiment may be provided inside the storage tank 10 and may preferably be installed in the lower part of the storage tank 10 and near the bottom surface of the storage tank 10 The fuel supply pump 11 pumps the liquefied natural gas stored in the lowermost part of the storage tank 10 and supplies it to the high pressure pump 20. [

The fuel supply pump 11 transfers the liquefied natural gas stored in the storage tank 10 from inside the storage tank 10 to the high pressure pump 20 and adjusts the size of the storage tank 10, The discharge pressure and the flow rate can be determined depending on the pressure drop of the pipe connecting the high-pressure pump 20 and the amount of the fuel gas to be supplied to the engines ME and GE.

The high pressure pump 20 of this embodiment can compress the cryogenic liquefied natural gas discharged from the fuel supply pump 11 to a high pressure. The liquefied natural gas is compressed by the high-pressure pump 20 to a high pressure, and then the temperature rises by compression. Preferably, the liquefied natural gas maintains a liquid state even when the temperature rises.

For example, the high-pressure pump 20 compresses the liquefied natural gas at about-1.2 bar, -163 ° C discharged from the storage tank 10 to a pressure of about 300 bar and pressurizes the liquefied natural gas May be in a liquid state at about 300 bar, -154 占 폚.

In addition, the high-pressure pump 20 of the present embodiment may be of a piston type, and the flow rate may be adjusted by a method of controlling the rotation speed.

The vaporizer 30 of this embodiment is a kind of heat exchanger that heats the liquefied natural gas compressed at a high pressure by the high pressure pump 20 using a heat source so that the compressed liquefied natural gas in the vaporizer 30 is supplied with heat energy, Can be vaporized in a gaseous state.

For example, the vaporizer 30 may heat the compressed liquefied natural gas to a temperature of about -50 DEG C, and the natural gas vaporized in the vaporizer 30 may be in a state of about 300 bar, -50 DEG C.

The heat source for heating the compressed and liquefied natural gas in the vaporizer 30 may be steam or glycol water. The glycol water may recover the waste heat of the combustion apparatus in the seawater or ship, However, the heat source of the vaporizer 30 is not limited thereto.

The expansion valve 40 of the present embodiment may be a Joule-Thomson valve for thermally expanding the high-pressure natural gas that has passed through the vaporizer 30 and may be a high-pressure natural gas Can be cooled by expansion, and the temperature decrease of the fluid is further reduced as the difference between before and after passing through the expansion valve (40) is greater.

In this embodiment, the expansion valve 40 may be capable of monolithically expanding high pressure natural gas to about 17 bar.

For example, when the liquefied natural gas is to be supplied to the autocycle engine, particularly the X-DF engine (ME) as fuel gas, the high pressure natural gas passing through the vaporizer 30 can be expanded to about 17 bar, The natural gas passing through the valve 40 may be in the state of about 17 bar, -102.5 DEG C and is cooled by expansion to form a gas-liquid mixture.

Further, when the liquefied natural gas is to be supplied to the autocycle engine, in particular, the electric power generating engine (GE) as the fuel gas, the high pressure natural gas passing through the vaporizer 30 can be expanded to about 7 bar, 40) may be in a vapor-liquid mixture state at about 7 bar, -122.5 ° C.

The gas-liquid separator 50 of this embodiment separates the gas-liquid mixture formed in the expansion valve 40 and separates the liquid from the liquefied natural gas recovery line RL And the separated gas is supplied as fuel to the autocycle engine (ME, GE) along the liquefied natural gas fuel line LL connected to the upper portion of the gas-liquid separator 50.

In this embodiment, the gas-liquid separator 50 is means for regulating the methane price of the fuel gas supplied to the engines ME and GE.

The methane number is a numerical value showing the resistance to knocking phenomenon. The knocking phenomenon is a phenomenon in which a mixture in which fuel and combustion air are mixed is compressed at an upward stroke of the piston in an engine cylinder, Explosion is caused by reaching the spontaneous ignition temperature. It is accompanied by strong noise and impact, shortening the life of the engine and lowering the engine output. Therefore, the fuel supplied to the engine must be regulated so as to have the methane required by the engine.

The smaller the number of carbon atoms in the fuel, the greater the ratio of hydrogen / carbon, the greater the methane concentration. The greater the methane content, the greater the resistance to knocking.

In this embodiment, the gas component separated from the gas-liquid separator 50 and supplied as fuel to the engines ME and GE may mainly contain a small amount of heavy hydrocarbon components as methane (CH ₄ ) And the liquid component recovered into the storage tank 10 is mainly a hydrocarbon component such as ethane, propane, and butane.

Therefore, the gas-liquid separator 50 of this embodiment can supply fuel gas having a high methane value to the engine (ME, GE), because the gas-liquid separator 50 makes the component supplied as the fuel mainly methane having a small carbon number.

In this embodiment, the gas-liquid mixture fed to the gas-liquid separator 50, the gas component separated from the gas-liquid separator 50 and discharged into the liquefied natural gas fuel line LL, The composition of the liquid component discharged into the line RL can be operated as shown in Table 1 below.

The composition of the fluid shown in Table 1 is based on the HYSYS simulation and simulated assuming that it is liquefied natural gas of about 1.2 bar, -163 ° C., and 500 kg / hr supplied by the fuel supply pump 11. As shown in Table 1, the gas component separated and discharged from the gas-liquid separator 50 has a high concentration of methane, a small fraction of the heavy hydrocarbons, and a high fraction of the heavy hydrocarbons in the liquid component.

In addition, the composition shown in Table 1 shows only the main components, and n-Butane, i-Pentane, Nitrogen, N ₂ , Carbon Dioxide, CO ₂ ) Are omitted, so that the sum of the compositions shown in Table 1 may not necessarily be 1.0000.

Gas mixture (Inlet) Outlet Liquid Component (Outlet) Methane 0.8709 0.9943 0.6196 Ethane 0.0854 0.0056 0.2479 Propane 0.0311 0.0001 0.0944 i-Butane 0.0116 0.0000 0.0351

The methane gas is determined by the composition of the fuel gas to be supplied and the liquefied natural gas is supplied in accordance with the characteristics of the fuel gas supply system because methane is a main component and also a small amount of ethane, propane, butane, pentane, nitrogen, The composition of the fuel gas can be changed and the methane is also changed accordingly.

According to the present embodiment, since the liquefied natural gas stored in the lowermost part of the storage tank 10 is transferred by using the fuel supply pump 11 as fuel and is vaporized and supplied, And more methane is higher than the evaporation gas having a high molar ratio of the hydrocarbons such as ethane and propane. Therefore, it is possible to supply more suitable fuel and vaporize the natural gas in the liquid state by using the high-pressure pump 20 and the vaporizer 30 , Or may be supplied as a fuel of an autocycle engine requiring a medium or low pressure fuel rather than a diesel cycle engine requiring a relatively high pressure fuel, the methane gas may be regulated and supplied using the gas-liquid separator 50.

2, the gas component separated in the gas-liquid separator 50 can be supplied to the engines ME and GE as fuel gas, and the liquefied natural gas The fuel line LL may further include a fuel gas heater 60 which heats the fuel gas supplied from the gas-liquid separator 50 to the engines ME and GE to a temperature required by the engines ME and GE have.

In this embodiment, the fuel gas supplied to the engine (ME, GE) can be heated to about 45 DEG C in the fuel gas heater (60).

2, the liquefied natural gas fuel line LL is connected from the storage tank 10 to the auto-cycle engine, but the X-DF engine ME and the electric power generation engine GE And the rear end of the fuel gas heater 60, and can supply the fuel gas meeting the conditions required by the respective engines. However, the branch point is not necessarily limited thereto.

2, the liquefied natural gas fuel line LL is connected to the X-DF engine ME from the storage tank 10 and is connected to the X-DF engine ME from the liquefied natural gas fuel line LL, The fuel gas branch line LB branched from the front end of the DF engine ME can be further connected to supply the liquefied natural gas fuel to the electric power generation engine GE and the liquefied natural gas There is further provided a pressure reducing valve 70 for reducing the pressure of the fuel gas flowing from the fuel line LL into the fuel gas branch line LB to meet the fuel condition of the power generation engine GE.

That is, the liquefied natural gas stored in the storage tank 10 is compressed, vaporized and expanded through the liquefied natural gas fuel line LL to the engines ME and GE, Diesel engine (ME) and a power generation engine (GE) are connected to an engine (10) to an autocycle engine (ME, GE) and supply liquefied natural gas fuel only to an X- When the gas is simultaneously supplied, the pressure and temperature of the fuel gas are controlled so as to satisfy the fuel condition of the X-DF engine (ME) by controlling the high-pressure pump 20, the vaporizer 30, the expansion valve 40, The valve 70 can be used to control the pressure of the fuel gas supplied to the electric power generation engine GE to meet the fuel condition of the electric power generation engine GE.

In this embodiment, the fuel gas supplied to the X-DF engine (ME) through the liquefied natural gas fuel line (LL) may be about 17 bar and 45 캜 and may flow from the liquefied natural gas fuel line (LL) The flow rate of the fuel gas branched into the branch line LB and supplied to the power generation engine GE through the pressure reducing valve 70 may be about 6.5 bar and 45 deg.

Further, when liquefied natural gas is supplied as fuel to the engine GE for power generation through the liquefied natural gas fuel line LL, it is also possible to expand the compressed and vaporized natural gas in the expansion valve 40 to about 7 bar have .

2, the liquefied natural gas fuel supply line LL is provided with a liquefied natural gas (LNG) compressed between the high-pressure pump 20 and the vaporizer 30 and compressed by the high-pressure pump 20, And a liquefied natural gas cooler 31 that is separated from the gas-liquid separator 50 and heat-exchanges the liquid component recovered to the storage tank 10 along the liquefied natural gas recovery line RL.

For example, in the liquefied natural gas cooler 31, the compressed liquefied natural gas of about 300 bar and -154 ° C. compressed by the high-pressure pump 20 and the compressed natural gas of -154 ° C. separated from the gas-liquid separator 50 and recovered to the storage tank 10 The liquid component at -122.5 DEG C is heat-exchanged, and the compressed liquefied natural gas is preheated before being supplied to the vaporizer 40, and the liquid component is cooled before being recovered to the storage tank 10. [ Liquefied natural gas, which is discharged from the liquefied natural gas cooler 31 after being subjected to heat exchange and is supplied to the vaporizer 40, is heated to about 300 bar and -149.3 DEG C, and the liquid component, which is discharged after heat exchange and is recovered to the storage tank 10, -140 to -152 < 0 > C.

Therefore, according to the present embodiment, the liquid component separated in the gas-liquid separator 50 and re-supplied to the storage tank 10 can be cooled and recovered to the storage tank 10 at a lower temperature, It is possible to minimize the amount of boil-off gas (BOG) generated in the combustion chamber.

The fuel supply system for a liquefied natural gas fuel vessel according to an embodiment of the present invention is a system for supplying liquefied natural gas to an engine (ME, GE) using a high-pressure pump (20) and a vaporizer (30) And an evaporative gas fuel line GL for supplying evaporative gas generated by spontaneous vaporization in the storage tank 10 together with the fuel line LL to the fuel of the autocycle engine ME and GE.

The evaporated gas fuel line GL in this embodiment can be connected from the storage tank 10 to the liquefied natural gas fuel line LL as shown in Figure 2 and is preferably connected to the rear end of the fuel gas heater 60 You can join.

The evaporated gas fuel line GL may further include an evaporated gas branch line GB1 branched from the evaporated gas fuel line GL and connected to the gas-liquid separator 50 of the liquefied natural gas fuel line LL And the evaporation gas branch line GB1 may be provided with an evaporation gas expansion valve 41 for swelling the fluid supplied to the gas-liquid separator 50.

The evaporated gas fuel line GL may be provided with a multi-stage compressor MC for compressing the evaporated gas discharged from the storage tank 10 and an evaporative gas cooler 32 for cooling the evaporated gas compressed by the multi-stage compressor MC have.

The multi-stage compressor MC includes a plurality of compressors for compressing the evaporation gas into a plurality of stages, a plurality of intercoolers provided at the downstream stages of the compressors for cooling the evaporated gas whose temperature has been increased by compression, . ≪ / RTI >

In the present embodiment, the multi-stage compressor MC is a means for treating the evaporated gas generated in the storage tank 10. When a problem such as failure of the high-pressure pump 20 or the vaporizer 30 occurs Liquid separator 50 and supply it to the power generation engine GE, either directly or through the gas-liquid separator 50. [

The multi-stage compressor (MC) of the present embodiment includes two compressors and two intercoolers, two-stage compressors for compressing the evaporation gas in two stages, or one compressor and one intercooler, And may be a single stage compressor that compresses over.

In the evaporative gas cooler 32 of the present embodiment, the evaporated gas compressed by the multi-stage compressor MC is heat-exchanged with the liquefied natural gas compressed by the high-pressure pump 20 in the liquefied natural gas fuel line LL described above, Stage compressor (MC) by using the cold heat of the liquefied natural gas compressed in the multi-stage compressor (20).

That is, in the evaporative gas cooler 32, the compressed liquefied natural gas compressed by the high-pressure pump 20 is heated and discharged, and the compressed evaporative gas compressed by the multi-stage compressor MC is cooled and discharged.

Preferably, the evaporative gas cooler 32 may be provided at the downstream end of the liquefied natural gas cooler 31 described above. That is, the compressed liquefied natural gas compressed by the high-pressure pump 20 is heat-exchanged with the re-liquefied natural gas separated from the gas-liquid separator 50 in the liquefied natural gas cooler 31 and recovered to the storage tank 10, And is heat-exchanged with the compressed evaporative gas compressed in the multi-stage compressor MC in the evaporative gas cooler 32, and then may be secondarily heated and then supplied to the evaporator 30.

Further, in this embodiment, the compressed evaporation gas may further include a cooler bypass line (GB) for bypassing the evaporative gas cooler 32 and joining to the downstream end of the evaporative gas cooler 32. Preferably, The evaporated gas generated by natural vaporization in the tank 10 is compressed by the multi-stage compressor MC and then bypassed through the evaporator gas cooler 32 along the cooler bypass line GB to join the rear end of the fuel gas heater 60, The evaporated gas generated during the operation of the high-pressure pump 20 is compressed in the multi-stage compressor MC and then cooled in the evaporative gas cooler 32 and then expanded in the evaporative gas expansion valve 41 along the evaporative gas branch line GB1 Liquid separator 50, as shown in FIG.

The evaporation gas expansion valve 41 must be capable of expanding to the same pressure as the expansion valve 40 of the liquefied natural gas fuel line LL described above and the evaporated gas cooled in the evaporation gas cooler 32 must be expanded to the liquefied natural gas Liquid separator 50 through the fuel line LL, that is, about -50 DEG C in the present embodiment.

That is, the evaporated gas supplied to the gas-liquid separator 50 along the evaporative gas branch line GB1 and the liquefied natural gas supplied to the gas-liquid separator 50 along the liquefied natural gas fuel line LL are supplied at the same pressure and temperature So that the gas-liquid separation performance is not impaired.

Although not shown, the fuel supply system for a liquefied natural gas fuel vessel according to the present invention is not limited to the above-described evaporative gas fuel line GL, and can be used as a means for treating the evaporative gas generated in the storage tank 10, (Gas Combustion Unit) may be provided. That is, the evaporated gas generated in the storage tank 10 may be burned without being used as fuel for the autocycle engine.

As described above, the fuel supply system and method for a liquefied natural gas fuel vessel of the present invention is characterized in that the LFS, particularly the vessel equipped with the autocycle engine such as the low pressure two stroke dual fuel oil engine (2SDFME) and the double fuel oil power generation engine (DFDG) The present invention relates to a system and a method for supplying a fuel gas to a high pressure pump 20 for compressing a liquefied natural gas from a liquid state to a high pressure and a vaporizer 30 for vaporizing a compressed liquefied natural gas, , An expansion valve (40) for monotonically expanding the vaporized natural gas, and a gas-liquid separator (50) for gas-liquid separating the gas-liquid mixture formed by the expansion, so as to satisfy the condition of the fuel gas required by the low- And it is possible to save the operation cost and especially the power energy cost by utilizing the high pressure pump compared to the method using the conventional evaporative gas compressor And it can reduce the footprint and cost of installing the equipment.

Further, even if fuel is supplied to the low-pressure autocycle engine by using the high-pressure pump 20 and the carburetor 30, the methane price can be adjusted, and some vaporized gas is re-liquefied and recovered to the storage tank 10, The amount of the evaporation gas spontaneously vaporized in the evaporator 10 can be minimized.

According to the present invention, the flow rate of the high-pressure pump 20 is controlled by a control unit (not shown) and the temperature and pressure of various devices constituting the system are controlled, The fuel can be supplied at a desired flow rate of the fuel gas while maintaining the temperature and the pressure easily.

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 and scope of the invention. It is.

10: Storage tank
11: Fuel supply pump
20: High pressure pump
30: vaporizer
40: expansion valve
50: gas-liquid separator
60: Fuel gas heater
70: Pressure reducing valve
ME: Low pressure two stroke double fuel oil engine
GE: Dual fuel oil power generation engine
LL: Liquefied natural gas fuel line
RL: Liquefied natural gas recovery line
31: Liquefied natural gas cooler
32: Evaporative gas cooler

Claims (17)

An autocycle engine operating with an Otto Cycle using liquefied natural gas as fuel;
A high pressure pump for compressing the liquefied natural gas discharged from the storage tank;
A vaporizer for vaporizing the liquefied natural gas compressed by the high-pressure pump;
An expansion valve for swelling the natural gas vaporized in the vaporizer; And
And a gas-liquid separator for gas-liquid separating the gas-liquid mixture formed by the expansion valve,
Liquid separator for recovering the liquid separated from the gas-liquid separator to the fuel of the autocycle engine to regulate the methane value of the natural gas fuel supplied to the autocycle engine, Fuel supply system of natural gas fuel vessel. The method according to claim 1,
Further comprising a liquefied natural gas cooler for heat-exchanging the liquefied natural gas compressed by the high-pressure pump and supplied to the vaporizer and the liquid separated from the gas-liquid separator and recovered into the storage tank,
Wherein the compressed liquefied natural gas supplied to the vaporizer from the liquefied natural gas cooler is heated and the liquid recovered in the storage tank is cooled. The method of claim 2,
Further comprising: a fuel gas heater for heating natural gas fuel separated from the gas-liquid separator and supplied to the fuel of the autocycle engine,
Wherein the natural gas fuel passed through the expansion valve and the fuel gas heater has a temperature required by the autocycle engine. The method of claim 3,
In the above-described auto-cycle engine,
An X-DF engine which is a 2-stroke engine as the propulsion engine of the ship; And
And a DFDG (Dual Fuel Diesel Generator Engine) as a 4-stroke engine as an auxiliary power production engine for the ship,
Wherein the natural gas fuel passing through the fuel gas heater has a temperature and a pressure required by the X-DF engine. The method of claim 4,
Further comprising a pressure reducing valve for reducing the pressure of the natural gas fuel to be supplied to the DFDG,
Wherein the natural gas fuel passing through the fuel gas heater and the pressure reducing valve has a pressure required by the DFDG. 5. The method according to any one of claims 1 to 4,
A liquefied natural gas fuel line providing a path through which the liquefied natural gas is supplied to the engine from the storage tank through the high pressure pump and the vaporizer; And
And an evaporative gas fuel line for providing a path through which evaporative gas generated in the storage tank is supplied as fuel of the engine,
In the evaporative gas fuel line,
A compressor for compressing the evaporation gas; And
And an intermediate cooler for cooling the evaporated gas heated by compression in the compressor. The method of claim 6,
And an evaporative gas cooler for exchanging the compressed and cooled evaporated gas with the compressed natural gas to be supplied to the vaporizer,
Wherein the evaporative gas cooler heats the compressed liquefied natural gas supplied to the vaporizer, and the evaporated gas is cooled. The method of claim 7,
And an evaporative gas expansion valve for expanding the compressed evaporative gas cooled in the evaporative gas cooler to the same pressure as the gas-liquid mixture fed to the gas-liquid separator. The method of claim 8,
And a control unit for controlling the temperature, pressure and flow rate of the fluid supplied to or discharged from the high-pressure pump, the vaporizer, the expansion valve, and the gas-liquid separator in accordance with the load variation of the autocycle engine. Supply system. 5. The method according to any one of claims 1 to 4,
And a GCU (Gas Combustion Unit) for processing the evaporative gas generated in the storage tank. 1) compressing the liquefied natural gas discharged from the storage tank using a high-pressure pump;
2) vaporizing the compressed liquefied natural gas using a vaporizer;
3) expanding the vaporized natural gas;
4) gas-liquid separation of the gas-liquid mixture formed by the expansion; And
5) supplying the gas-liquid separated liquid to the storage tank and supplying the gas-liquid separated gas to an autocycle engine that operates according to an autocycle using liquefied natural gas as fuel,
Wherein the liquefied natural gas stored in the storage tank can be supplied as fuel having the temperature, pressure and methane required by the autocycle engine. The method of claim 11,
(1-1) exchanging the compressed liquefied natural gas with the liquid re-supplied to the storage tank in the step (5) before vaporizing the compressed liquefied natural gas in the step (2)
The compressed liquefied natural gas is heated by a liquid supplied to the storage tank again and then vaporized,
Wherein the liquid re-supplied to the storage tank is cooled by the compressed liquefied natural gas and then supplied to the storage tank. The method of claim 12,
5-1) heating the gas fuel supplied to the engine by gas-liquid separation in the step 5); And
And a control step of controlling the pressure, the temperature and the flow rate of the fluid in any one of the above steps according to the load variation of the auto-cycle engine,
Wherein the fluid having passed the step 5-1) has a pressure, a temperature and a methane price required by the autocycle engine. 14. The method of claim 13,
5-2) decompressing the heated gaseous fuel,
Wherein the fluid having passed through the step 5-2) has a pressure, a temperature and a methane value required by the autocycle engine. 15. The method of claim 14,
Discharging the evaporated gas generated in the storage tank and compressing it in a compressor; And
And supplying the compressed vaporized gas to the fuel of the autocycle engine,
Wherein said compressed evaporation gas has the pressure and temperature required by said autocycle engine. 16. The method of claim 15,
Further comprising the step of expanding said compressed evaporative gas,
And the expanded evaporation gas is joined to the fuel of the autocycle engine in the step 4). 16. The method according to claim 15 or 16,
And cooling the compressed evaporative gas by exchanging heat between the compressed evaporative gas and the compressed liquefied natural gas supplied to the evaporator in the step 2)
And supplying the compressed and cooled evaporated gas to the fuel of the autocycle engine.

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