KR102665822B1 - Fuel Supply System and Method of Engine for Vessel - Google Patents

Abstract

A fuel supply system for a marine engine is disclosed.
The fuel supply system for the marine engine includes a multi-stage compressor that compresses evaporative gas discharged from a storage tank in multiple stages; A second pump that compresses the liquefied natural gas discharged from the storage tank; A second heat exchanger that cools the liquefied natural gas discharged from the storage tank by heat-exchanging the liquefied natural gas returned to the storage tank with a refrigerant; A vaporizer that vaporizes liquefied natural gas used as a refrigerant in the second heat exchanger; A first heater that heats the remaining liquefied natural gas that is not sent to the vaporizer among the liquefied natural gas used as a refrigerant in the second heat exchanger; and a gas-liquid separator that is heated by the first heater and separates partially vaporized natural gas from liquefied natural gas remaining in a liquid state, wherein the natural gas separated by the gas-liquid separator is supplied to the second engine, The liquefied natural gas separated by the gas-liquid separator is cooled by the second heat exchanger and then returned to the storage tank, and the natural gas separated by the gas-liquid separator has a methane content compared to the fluid supplied to the gas-liquid separator. increases, the liquefied natural gas separated by the gas-liquid separator has a higher content of heavy hydrocarbons compared to the fluid supplied to the gas-liquid separator, and the second engine is an engine that requires a methane number above a certain value.

Description

Fuel supply system and method for marine engines {Fuel Supply System and Method of Engine for Vessel}

The present invention relates to a system and method for supplying fuel to a marine engine using liquefied natural gas as fuel, by vaporizing liquefied natural gas stored in a storage tank and supplying it as fuel to the engine, or by using evaporation gas generated inside the storage tank to fuel the engine. It relates to a system and method for supplying fuel to

Natural gas is usually liquefied and transported over long distances as liquefied natural gas (LNG). Liquefied natural gas is obtained by cooling natural gas to a cryogenic temperature of approximately -163°C at atmospheric pressure, and its volume is significantly reduced compared to the gaseous state, making it very suitable for long-distance transportation through the sea.

Even if the liquefied natural gas storage tank is insulated, there is a limit to completely blocking external heat, and the liquefied natural gas is continuously vaporized within the storage tank due to the heat transferred into the liquefied natural gas. Liquefied natural gas vaporized inside a storage tank is called boil-off gas (BOG; Boil-Off Gas).

When the pressure in the storage tank exceeds the set pressure due to the generation of boil-off gas, the boil-off gas is discharged to the outside of the storage tank. The evaporative gas discharged outside the storage tank is used as fuel for the engine or is re-liquefied and returned to the storage tank.

Typically, the boil-off gas re-liquefaction device has a refrigeration cycle, and the boil-off gas is cooled by this refrigeration cycle to re-liquefy the boil-off gas. To cool the boil-off gas, heat exchange is performed with a cooling fluid. A partial re-liquefaction system (PRS) is used, which uses the boil-off gas itself as a cooling fluid to self-exchange heat.

Meanwhile, among engines generally used in ships, there are ME-GI engines and DF (Dual Fuel) engines that can use natural gas as fuel.

Recently, as international regulations to prevent air pollution have been strengthened, the fuel for ships is changing from fuel oil to natural gas. Natural gas has a low sulfur content and does not produce sulfur compounds or soot substances during combustion, making it relatively environmentally friendly. In line with recent trends, the ME-GI engine, which can use natural gas along with fuel oil, has been developed.

The ME-GI engine consists of two strokes and adopts the diesel cycle, which injects high-pressure natural gas around 300 bar directly into the combustion chamber near the top dead center of the piston.

The diesel cycle follows a constant pressure process where the pressure when combustion occurs near top dead center is constant, and only combustion air is sucked into the cylinder during the upward stroke, and the sucked combustion air is adiabatically compressed at a high compression ratio. At top dead center, the combustion air reaches a considerably high temperature due to adiabatic compression during the compression stroke, and when fuel is injected into the adiabatically compressed combustion air, spontaneous combustion occurs due to the high temperature.

In a diesel cycle, although the pressure of combustion air reaching top dead center is already high, the fuel injection pressure is appropriately adjusted to prevent the pressure from increasing further due to explosion due to fuel injection, so that the combustion pressure of the fuel at top dead center is maintained at a constant level. keep it that way

In diesel engines, combustion efficiency increases as the compression ratio of the fuel increases, but considering explosion pressure, the fuel is generally compressed at a compression ratio of about 15 to 22:1.

In addition, since only air is compressed in a diesel engine during the compression stroke, knocking, which is a phenomenon in which premature ignition occurs before the piston reaches top dead center, does not fundamentally occur.

The DF engine consists of a 4-stroke cycle and adopts the Otto Cycle, which injects natural gas with a relatively low pressure of about 6.5 bar into the combustion air inlet and compresses it as the piston rises.

The Otto cycle follows a static process where the volume is constant when combustion occurs near top dead center, and the mixture of fuel and combustion air is introduced into the cylinder and compressed together before the upward stroke. The mixture flowing into the cylinder is adiabatically compressed and its temperature rises. If the mixture reaches a temperature that is too high, early ignition may occur. Therefore, the compression ratio of the Otto cycle is set lower than that of the diesel cycle.

Since the compression ratio of the Otto cycle is set relatively low, it is necessary to reach a high pressure when the fuel explodes at top dead center by an ignition source, and exploding the fuel in the shortest possible time helps increase engine efficiency.

In engines that follow the Otto cycle, the mixture of fuel and combustion air is introduced into the cylinder before the upward stroke, so early ignition may occur before ignition by the ignition source, and knocking may occur.

If knocking occurs, engine efficiency may decrease and engine damage may occur, so it is important to operate engines that follow the Otto cycle to prevent knocking.

Anti-knocking performance of fuel used in engines following the Otto cycle is determined by octane number for liquid fuel and methane number for gaseous fuel. For DF engines, a methane number of 80 or higher is required.

In the case of the DF engine following the Otto cycle, the efficiency is lower than that of the ME-GI engine following the diesel cycle, but the combustion temperature of the fuel is not high and the amount of nitrogen oxides (NOx) generated due to high heat is small. It has the advantage of satisfying IMO Tier Ⅲ nitrogen oxide regulations.

1 is a schematic diagram of a fuel supply system for a conventional marine engine.

Referring to FIG. 1, the fuel supply system of a conventional marine engine includes a boil-off gas supply system that supplies boil-off gas discharged from a storage tank (T) to the engines (E1 and E2), and a liquefaction gas inside the storage tank (T). It includes a liquefied natural gas supply system that supplies natural gas to engines (E1, E2). In addition, the fuel supply system for a conventional marine engine may further include a re-liquefaction system for re-liquefying excess evaporative gas remaining after being used as fuel for the engines E1 and E2.

The boil-off 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, and a second It includes a pressure reducing device 420, and the reliquefaction system includes a first heat exchanger 110, a first pressure reducing device 410, and a gas-liquid separator 500.

The multi-stage compressor 200 compresses the boil-off gas discharged from the storage tank (T) in multiple stages, and includes a plurality of compressors (210, 220, 230, 240, 250) and a plurality of coolers installed alternately with the compressor at the rear of the compressor. It includes (310, 320, 330, 340, 350), and generally a multi-stage compressor is used that compresses the boil-off gas in five stages by five compressors and five coolers.

In addition, the multi-stage compressor 200 may include one or multiple recirculation lines. When the multi-stage compressor 200 has 5 stages, as shown in FIG. 1, it branches off from the rear end of the first cooler 310 and A first recirculation line (L1) that joins the front end of the compressor (210), and a second recirculation line (L2) that branches off from the rear end of the fifth cooler (350) and joins between the third cooler (330) and the fourth compressor (240). may include.

The boil-off gas compressed through all stages of the multi-stage compressor 200 is sent to the first engine (E1), and the boil-off gas compressed through only some stages of the multi-stage compressor 200 is branched in the middle (L3 line) to the second engine (E1). It is sent to the engine (E2). The first engine (E1) may be a ME-GI engine, and the second engine (E2) may be a DF engine.

The first pump 610 is installed inside the storage tank (T) and discharges the liquefied natural gas stored in the storage tank (T), and the second pump 620 discharges the liquefied natural gas stored in the storage tank (T) by the first pump (610). The liquefied natural gas discharged from (T) is compressed to the required pressure of the first engine (E1).

The vaporizer 700 forcibly vaporizes the liquefied natural gas compressed by the second pump 620. A portion of the natural gas forcibly vaporized by the vaporizer 700 is supplied to the first engine E1, and the remainder is supplied to the first heater 810.

The first heater 810 heats the natural gas vaporized by the vaporizer 700 to the temperature required by the second engine E2, and the second pressure reducing device 420 heats the natural gas vaporized by the vaporizer 700 to the temperature required by the second engine E2. The heated natural gas is decompressed to the pressure required by the second engine (E2).

1 shows that the first heater 810 is installed at the rear of the vaporizer 700, and the second pressure reducing device 420 is installed at the rear of the first heater 810, but the first heater 810 and the second The decompression device 420 and its installation order may be changed, and the second decompression device 420 may be installed at the rear of the vaporizer 700, and the first heater 810 may be installed at the rear of the second decompression device 420. .

The first heat exchanger 110 cools the partially branched boil-off gas (L5 line) after being compressed through all stages of the multi-stage compressor 200 by heat-exchanging the boil-off gas discharged from the storage tank (T) with a refrigerant. . Among the evaporative gases discharged from the storage tank (T), the surplus evaporative gas that is not supplied to the first engine (E1) or the second engine (E2) is supplied to the first heat exchanger (110) and undergoes a re-liquefaction process. will be.

The first pressure reducing device 410 expands the fluid (L5 line) compressed by the multi-stage compressor 200 and then cooled by the first heat exchanger 110. The boil-off gas that has undergone a compression process by the multi-stage compressor 200, a cooling process by the first heat exchanger 110, and an expansion process by the first decompression device 410 is partially or entirely re-liquefied.

The gas-liquid separator 500 separates the liquefied natural gas that has been re-liquefied while passing through the multi-stage compressor 200, the first heat exchanger 110, and the first pressure reducing device 410, and the boil-off gas remaining in a gaseous state. . The liquefied natural gas separated by the gas-liquid separator 500 is returned to the storage tank (T), and the gaseous boil-off gas separated by the gas-liquid separator 500 joins the boil-off gas discharged from the storage tank (T). and is used as a refrigerant in the first heat exchanger (110).

If the second engine (E2) is an engine that follows the Otto cycle, such as a DF engine, the methane value of the natural gas supplied to the second engine (E2) must be adjusted to prevent knocking, which is forced by the liquefied natural gas supply system. In the case of vaporized natural gas, the methane number is lower than that of naturally vaporized boil-off gas supplied by the boil-off gas supply system.

According to the liquefied natural gas supply system, the liquefied natural gas at the bottom of the storage tank (T) is discharged and forcibly vaporized by the first pump 610 installed at the bottom of the storage tank (T), so the proportion of components with a relatively large specific gravity is high. Because.

Therefore, there is a need to control the methane number of natural gas that is forcibly vaporized by the liquefied natural gas supply system, and the present invention provides a fuel supply system and method for a marine engine that can control the methane number of natural gas supplied as fuel for the engine. We would like to provide

According to one aspect of the present invention for achieving the above object, a multi-stage compressor that compresses the boil-off gas discharged from the storage tank in multiple stages; A second pump that compresses the liquefied natural gas discharged from the storage tank; A second heat exchanger that cools the liquefied natural gas discharged from the storage tank by heat-exchanging the liquefied natural gas returned to the storage tank with a refrigerant; A vaporizer that vaporizes liquefied natural gas used as a refrigerant in the second heat exchanger; A first heater that heats the remaining liquefied natural gas that is not sent to the vaporizer among the liquefied natural gas used as a refrigerant in the second heat exchanger; and a gas-liquid separator that is heated by the first heater and separates partially vaporized natural gas from liquefied natural gas remaining in a liquid state, wherein the natural gas separated by the gas-liquid separator is supplied to the second engine, The liquefied natural gas separated by the gas-liquid separator is cooled by the second heat exchanger and then returned to the storage tank, and the natural gas separated by the gas-liquid separator has a methane content compared to the fluid supplied to the gas-liquid separator. increases, the liquefied natural gas separated by the gas-liquid separator has a higher content of heavy hydrocarbons compared to the fluid supplied to the gas-liquid separator, and the second engine is a fuel for a marine engine, which is an engine requiring a methane number above a certain value. A supply system is provided.

The fuel supply system of the marine engine may further include a second heater that heats the natural gas separated by the gas-liquid separator to a temperature required by the second engine, and the natural gas separated by the gas-liquid separator is, After being heated by the second heater, it may be supplied to the second engine.

The fuel supply system of the marine engine may further include a second decompression device that depressurizes the natural gas separated by the gas-liquid separator to the pressure required by the second engine, and the second decompression device may It may be installed between a separator and the second heater, or between the second heater and the second engine.

The second engine may be a DF engine, the second heater may heat natural gas to 0° C. to 45° C., and the second pressure reducing device may depressurize the natural gas to 6.5 bar.

The fuel supply system of the marine engine may further include a first pump installed inside the storage tank to discharge liquefied natural gas.

The second heat exchanger is installed at a rear end of the second pump and can use liquefied natural gas compressed by the second pump as a refrigerant.

The second pump is installed at a rear end of the second heat exchanger and can compress the liquefied natural gas used as a refrigerant in the second heat exchanger.

The boil-off gas compressed through all stages of the multi-stage compressor can be sent to the first engine, and the boil-off gas compressed through only some stages of the multi-stage compressor can be branched in the middle and sent to the second engine.

Natural gas vaporized by the vaporizer may be supplied to the first engine, and the second pump may compress the liquefied natural gas to the required pressure of the first engine.

The first pump may be installed at the bottom of the storage tank.

The first engine may be a ME-GI engine, and the second pump may compress liquefied natural gas to 300 bar.

The multi-stage compressor may include a plurality of compressors and a plurality of coolers, and the plurality of coolers may be installed at rear ends of the plurality of compressors, and the plurality of compressors and the plurality of coolers may be installed alternately.

The multi-stage compressor can compress boil-off gas in five stages, including five compressors and five coolers.

According to another aspect of the present invention for achieving the above object, 1) heating liquefied natural gas discharged from a storage tank; 2) separating gas and liquid from the fluid heated in step 1); 3) cooling the liquefied natural gas separated in step 2) by exchanging heat in a second heat exchanger using the liquefied natural gas discharged from the storage tank as a refrigerant, and then returning it to the storage tank; and 4) supplying the natural gas separated in step 2) to a second engine, wherein the fluid used as a refrigerant of the second heat exchanger in step 3) is heated in step 1), The natural gas separated in step 2) has a higher content of methane than the fluid before gas-liquid separation, and the liquefied natural gas separated in step 2) has a higher content of heavy hydrocarbons than the fluid before gas-liquid separation. 2 A fuel supply method for a marine engine, which is an engine that requires a methane number above a certain value, is provided.

The fuel supply method for the marine engine may further include compressing the boil-off gas discharged from the storage tank to the pressure required by the first engine at the front or rear end of the second heat exchanger.

The fuel supply method for the marine engine may further include the step of 5) partially branching and vaporizing the fluid used as the refrigerant of the second heat exchanger in step 3), and the natural gas vaporized in step 5) may be supplied to the first engine.

The fuel supply method for the marine engine may further include heating the natural gas separated in step 2) to a temperature required by the second engine by a second heater, and then supplying the natural gas to the second engine. You can.

The fuel supply method for the marine engine includes depressurizing the natural gas separated in step 2) to the pressure required by the second engine at the front or rear end of the second heater and then supplying it to the second engine. More may be included.

According to another aspect of the present invention for achieving the above object, the liquefied natural gas discharged from the storage tank is heated and then gas-liquid is separated, the gas-liquid separated natural gas with an increased methane value is supplied to the DF engine, and the gas-liquid separated liquefaction is performed. Natural gas is provided as a fuel supply method for a marine engine, in which liquefied natural gas discharged from the storage tank is cooled by heat exchange with a refrigerant and then returned to the storage tank.

According to the present invention, requirements such as fuel temperature and pressure according to engine load changes can be satisfied in the same way as before, and knocking can be effectively prevented while minimizing the number of additional equipment compared to the prior art.

In addition, according to the present invention, the liquefied natural gas returned to the storage tank is cooled by heat exchange with the liquefied natural gas discharged from the storage tank and then sent to the storage tank, thereby minimizing the increase in temperature inside the storage tank.

1 is a schematic diagram of a fuel supply system for a conventional marine engine.
Figure 2 is a schematic diagram of a fuel supply system for a marine engine according to a first preferred embodiment of the present invention.
Figure 3 is a schematic diagram of a fuel supply system for a marine engine according to a second preferred embodiment of the present invention.
Figure 4 is a schematic diagram of a fuel supply system for a marine engine according to a third preferred embodiment of the present invention.

Hereinafter, the structure and operation of a preferred embodiment of the present invention will be described in detail with reference to the attached drawings. The following examples may be modified into various other forms, and the scope of the present invention is not limited to the following examples.

In the following examples, the case of liquefied natural gas is explained as an example, but the present invention can be applied to various liquefied gases, and the examples below can be modified into various other forms, and the scope of the present invention is limited to the examples below. It doesn't work.

In the following examples, the fluid flowing through each flow path may be in a gaseous state, a gas-liquid mixture state, a liquid state, or a supercritical fluid state, depending on the operating conditions of the system.

Figure 2 is a schematic diagram of a fuel supply system for a marine engine according to a first preferred embodiment of the present invention.

Referring to FIG. 2, the fuel supply system of the marine engine of this embodiment includes an evaporative gas supply system that supplies evaporative gas discharged from the storage tank (T) to the engines (E1 and E2), and a fuel supply system inside the storage tank (T). It includes a liquefied natural gas supply system that supplies liquefied natural gas to engines (E1 and E2).

The storage tank (T) that supplies boil-off gas and liquefied natural gas to the fuel supply system of the marine engine of this embodiment may be a membrane tank or a Type C tank, and can be selected depending on the installation location and capacity. However, the storage tank (T) that supplies boil-off gas and liquefied natural gas to the fuel supply system of the marine engine of this embodiment is preferably a membrane tank.

The boil-off gas supply system of this embodiment includes a multi-stage compressor 200, and the liquefied natural gas supply system of this embodiment includes a second pump 620, a second heat exchanger 120, a vaporizer 700, and a first heater. It includes (810), a gas-liquid separator (500), a second heater (820), and a second pressure reducing device (420).

The multi-stage compressor 200 of this embodiment compresses the boil-off gas discharged from the storage tank (T) in multiple stages, and includes a plurality of compressors (210, 220, 230, 240, 250) and a compressor alternately installed at the rear of the compressor. It includes a plurality of coolers (310, 320, 330, 340, 350). In Figure 2, a multi-stage compressor that compresses boil-off gas in five stages by five compressors and five coolers is shown as an example, but the present invention is not limited thereto.

Although not shown in FIG. 2, the multi-stage compressor 200 of this embodiment may include one or more recirculation lines the same or similar to the conventional one.

The boil-off gas compressed through all stages of the multi-stage compressor 200 of this embodiment is sent to the first engine (E1), and the boil-off gas compressed through only some stages of the multi-stage compressor 200 is branched in the middle (L3 line). ) is sent to the second engine (E2).

In Figure 2, it is shown as an example that evaporative gas compressed by three of the five compressors (210, 220, and 230) is partially branched and sent to the second engine (E2), but the present invention is not limited thereto. The first engine (E1) may be a ME-GI engine, and the second engine (E2) may be a DF engine.

The second pump 620 of this embodiment compresses the liquefied natural gas discharged from the storage tank (T) to the required pressure of the first engine (E1). When the first engine (E1) is a ME-GI engine, the second pump 620 compresses the liquefied natural gas at a pressure of approximately 300 bar, and the liquefied natural gas compressed by the second pump 620 is approximately It can be -154℃, 300 bar. Additionally, the second pump 620 of this embodiment may be of the piston type, and the flow rate may be adjusted by adjusting the rotation speed.

The second heat exchanger 120 of this embodiment uses liquefied natural gas compressed by the second pump 620 after being discharged from the storage tank (T) as a refrigerant, and uses liquefied natural gas separated by the gas-liquid separator 500 as a refrigerant. is cooled by heat exchange.

The liquefied natural gas separated by the gas-liquid separator 500 of this embodiment and then cooled by the second heat exchanger 120 may be approximately -150°C and is returned to the storage tank (T).

According to the fuel supply system for the marine engine of this embodiment, the liquefied natural gas returned to the storage tank (T) can be additionally cooled by the second heat exchanger (120), thereby reducing the temperature rise inside the storage tank (T). This can be prevented and the generation of evaporative gas inside the storage tank (T) can be suppressed.

In addition, the liquefied natural gas discharged from the storage tank (T), compressed by the second pump 620, and then used as a refrigerant in the second heat exchanger 120 is heated by the second heat exchanger 120 and then Since it is sent to the first heater 810 or the vaporizer 700, it can be heated or vaporized using less heat source than if it is sent directly to the first heater 810 or the vaporizer 700, which is efficient.

2 shows that the second heat exchanger 120 is installed at the rear end of the second pump 620. However, according to the fuel supply system of the marine engine of this embodiment, the second pump 620 is installed at the rear end of the second pump 620. ) It is installed at the rear end, and the liquefied natural gas discharged from the storage tank (T) may be used as a refrigerant in the second heat exchanger (120) and then compressed by the second pump (620).

The vaporizer 700 of this embodiment is compressed by the second pump 620 after being discharged from the storage tank T and a portion (L6 line) of the liquefied natural gas used as a refrigerant in the second heat exchanger 120. Vaporize. Natural gas vaporized by the vaporizer 700 is supplied as fuel to the first engine E1.

The natural gas vaporized by the vaporizer 700 of this embodiment may be approximately -50°C, and steam, seawater, or glycol water heated by recovered waste heat may be used as the heat source. In addition, the vaporizer 700 of this embodiment vaporizes the sum of the amount liquefied in the gas-liquid separator 500 and the amount of natural gas consumed in the second engine E2.

The first heater 810 of this embodiment is compressed by the second pump 620 after being discharged from the storage tank T and used as a refrigerant in the second heat exchanger 120, out of the liquefied natural gas used as a refrigerant in the vaporizer 700. ) The remaining liquefied natural gas that is not sent to is heated.

The gas-liquid separator 500 of this embodiment is heated by the first heater 810 and separates partially vaporized natural gas from liquefied natural gas remaining in a liquid state. The liquefied natural gas and natural gas separated by the gas-liquid separator 500 may be approximately -122.3°C.

The gaseous natural gas separated by the gas-liquid separator 500 of this embodiment is sent to the second heater 820, and the liquefied natural gas separated by the gas-liquid separator 500 is sent to the second heat exchanger 120. Lose.

The liquefied natural gas separated by the gas-liquid separator 500 of this embodiment and then sent to the second heat exchanger 120 is the liquefied natural gas compressed by the second pump 620 after being discharged from the storage tank (T). As a refrigerant, it is cooled by the second heat exchanger 120 and then returned to the storage tank (T).

The liquefied natural gas separated by the gas-liquid separator 500 of this embodiment has a high heavy hydrocarbon content, and the natural gas separated by the gas-liquid separator 500 has a high methane content. According to the fuel supply system for the marine engine of this embodiment, natural gas with a high methane content separated by the gas-liquid separator 500 can be supplied to the second engine (E2), thereby preventing the knocking phenomenon of the second engine (E2). It can be prevented.

As a result of simulation by HYSYS, the fluid supplied to the gas-liquid separator 500 of this embodiment consists of 86.74% methane, 12.25% ethane, and 1.01% propane, and the natural gas separated by the gas-liquid separator 500 It was confirmed that the composition was composed of 99.18% methane and 0.82% ethane.

The second heater 820 of this embodiment heats the gaseous natural gas separated by the gas-liquid separator 500 to the temperature required by the second engine E2. When the second engine E2 is a DF engine, the second heater 820 heats the natural gas to approximately 0°C to 45°C. Seawater, fresh water, steam, etc. may be used as the source of the second heater 820.

The second pressure reducing device 420 of this embodiment depressurizes the natural gas heated by the second heater 820 to the pressure required by the second engine E2. When the second engine (E2) is a DF engine, the second pressure reducing device 420 of this embodiment can depressurize natural gas to a pressure of approximately 6.5 bar. Natural gas heated by the second heater 820 and decompressed by the second pressure reducing device 420 is supplied as fuel to the second engine E2.

In Figure 2, it is shown that the second heater 820 is installed at the rear end of the gas-liquid separator 500, and the second pressure reducing device 420 is installed at the rear end of the second heater 820. However, the fuel of the marine engine of this embodiment According to the supply system, a second pressure reducing device 420 is installed at the rear of the gas-liquid separator 500, and a second heater 820 is installed at the rear of the second pressure reducing device 420, so that the gas-liquid separator 500 separates the gas-liquid separator 500. After the gaseous natural gas is decompressed to the pressure required by the second engine E2 by the second decompression device 420, the temperature required by the second engine E2 is reached by the second heater 820. It may be heated up to .

The liquefied natural gas supply system of this embodiment may further include a first pump 610 that is installed inside the storage tank (T) and discharges the liquefied natural gas stored in the storage tank (T).

The first pump 610 of this embodiment is installed at the bottom near the bottom of the storage tank (T), and the discharge pressure varies depending on the size of the storage tank (T), the pressure drop in the pipe, the flow rate of liquefied natural gas to be supplied, etc. and discharge flow rate are determined.

Figure 3 is a schematic diagram of a fuel supply system for a marine engine according to a second preferred embodiment of the present invention.

Referring to FIG. 3, the fuel supply system for the marine engine of this embodiment, like the first embodiment, includes a boil-off gas supply system that supplies boil-off gas discharged from the storage tank (T) to the engines (E1 and E2), It includes a liquefied natural gas supply system that supplies the liquefied natural gas inside the storage tank (T) to the engines (E1 and E2).

The storage tank (T), which supplies boil-off gas and liquefied natural gas to the fuel supply system of the marine engine of this embodiment, may be a membrane tank or Type C tank, as in the first embodiment, and the installation location and capacity It can be selected depending on the tank, and it is preferable to use a membrane tank.

The boil-off gas supply system of this embodiment, like the first embodiment, includes a multi-stage compressor 200, and the liquefied natural gas supply system of this embodiment, like the first embodiment, includes a second pump 620, 2 It includes a heat exchanger 120, a vaporizer 700, a gas-liquid separator 500, a second heater 820, and a second pressure reducing device 420.

However, unlike the first embodiment, the liquefied natural gas supply system of this embodiment further includes a third heat exchanger 130 and does not include the first heater 810.

The multi-stage compressor 200 of this embodiment, like the first embodiment, compresses the boil-off gas discharged from the storage tank (T) in multiple stages, and includes a plurality of compressors (210, 220, 230, 240, 250) and a rear end of the compressor. It includes a compressor and a plurality of coolers (310, 320, 330, 340, 350) installed alternately. In Figure 3, a multi-stage compressor that compresses boil-off gas in five stages by five compressors and five coolers is shown as an example, but the present invention is not limited thereto. Additionally, the multi-stage compressor 200 of this embodiment may include one or more recirculation lines, like the first embodiment.

According to the fuel supply system for the marine engine of this embodiment, like the first embodiment, the boil-off gas compressed through all stages of the multi-stage compressor 200 is sent to the first engine (E1), and the boil-off gas of the multi-stage compressor 200 The evaporative gas compressed through only a few stages is branched in the middle (L3 line) and sent to the second engine (E2).

In Figure 3, it is shown as an example that evaporative gas compressed by three of the five compressors (210, 220, and 230) is partially branched and sent to the second engine (E2), but the present invention is not limited thereto. The first engine (E1) may be a ME-GI engine, and the second engine (E2) may be a DF engine.

The second pump 620 of this embodiment, like the first embodiment, compresses the liquefied natural gas discharged from the storage tank (T) to the required pressure of the first engine (E1). When the first engine (E1) is a ME-GI engine, the second pump 620 compresses the liquefied natural gas at a pressure of approximately 300 bar, and the liquefied natural gas compressed by the second pump 620 is approximately It can be -154℃, 300 bar. Additionally, the second pump 620 of this embodiment may be of the piston type, and the flow rate may be adjusted by adjusting the rotation speed.

Like the first embodiment, the second heat exchanger 120 of this embodiment uses liquefied natural gas compressed by the second pump 620 after being discharged from the storage tank (T) as a refrigerant, and uses the gas-liquid separator 500 as a refrigerant. The separated liquefied natural gas is cooled by heat exchange.

The liquefied natural gas separated by the gas-liquid separator 500 of this embodiment and then cooled by the second heat exchanger 120 may be approximately -150°C, as in the first embodiment, and is stored in the storage tank (T). will be reinstated

According to the fuel supply system for the marine engine of this embodiment, like the first embodiment, the liquefied natural gas returned to the storage tank (T) can be additionally cooled by the second heat exchanger 120, so the storage tank ( T) It is possible to prevent internal temperature rise and suppress the generation of evaporative gas inside the storage tank (T).

In addition, the liquefied natural gas discharged from the storage tank (T), compressed by the second pump 620, and then used as a refrigerant in the second heat exchanger 120 is heated by the second heat exchanger 120 and then Since it is sent to the vaporizer 700, it can be vaporized using less heat source than if it is sent directly to the vaporizer 700, making it efficient.

3 shows that the second heat exchanger 120 is installed at the rear end of the second pump 620. However, according to the fuel supply system for the marine engine of this embodiment, like the first embodiment, the second pump 620 is installed at the rear of the second heat exchanger 120, and the liquefied natural gas discharged from the storage tank (T) may be used as a refrigerant in the second heat exchanger 120 and then compressed by the second pump 620. .

The third heat exchanger 130 of this embodiment uses the fluid (L7 line) discharged from the storage tank (T) and passed through the second pump 620 and the second heat exchanger 120 as a refrigerant, and uses the vaporizer (700) as a refrigerant. ) and then partially branched natural gas (L8 line) is cooled.

In order to increase the methane number by separating heavy hydrocarbons from natural gas, natural gas must be cooled to approximately -120°C or lower. According to the fuel supply system for the marine engine of this embodiment, natural gas is After cooling to -120°C or lower, it is supplied to the gas-liquid separator (500).

In addition, the fluid sent to the third heat exchanger 130 after being used as a refrigerant in the second heat exchanger 120 is further heated by the third heat exchanger 120 and then sent to the vaporizer 700, so it is immediately sent to the vaporizer 700. It is efficient because it can be vaporized using fewer heat sources than sending it to the vaporizer 700 or passing only the second heat exchanger 120 and then sending it to the vaporizer 700.

The vaporizer 700 of this embodiment vaporizes the fluid that has passed through the second pump 620, the second heat exchanger 120, and the third heat exchanger 120 after being discharged from the storage tank T. A portion of the natural gas vaporized by the vaporizer 700 is supplied as fuel to the first engine E1 (L9 line), and the remainder (L8 line) is supplied to the third heat exchanger 130.

The natural gas vaporized by the vaporizer 700 of this embodiment may be approximately -45°C, and like the first embodiment, glycol water heated by steam, seawater, or recovered waste heat is used as the heat source. ), etc. can be used.

The gas-liquid separator 500 of this embodiment separates gaseous natural gas and liquid liquefied natural gas from the fluid (L8 line) vaporized by the vaporizer 700 and then cooled by the third heat exchanger 130. Let's do it. The liquefied natural gas and natural gas separated by the gas-liquid separator 500 may be approximately -121.4°C.

According to the fuel supply system for the marine engine of this embodiment, like the first embodiment, the gaseous natural gas separated by the gas-liquid separator 500 is sent to the second heater 820 and is sent to the gas-liquid separator 500. The liquefied natural gas separated by is sent to the second heat exchanger (120).

The liquefied natural gas sent to the second heat exchanger 120 after being separated by the gas-liquid separator 500 of this embodiment is discharged from the storage tank T and then sent to the second pump 620, as in the first embodiment. The liquefied natural gas compressed by the refrigerant is cooled by the second heat exchanger 120 and then returned to the storage tank (T).

The liquefied natural gas separated by the gas-liquid separator 500 of this embodiment has a high heavy hydrocarbon content, and the natural gas separated by the gas-liquid separator 500 has a high methane content. According to the fuel supply system for the marine engine of this embodiment, as in the first embodiment, natural gas with a high methane content separated by the gas-liquid separator 500 can be supplied to the second engine E2, so that the second engine E2 The knocking phenomenon of (E2) can be prevented.

As a result of simulation by HYSYS, the fluid supplied to the gas-liquid separator 500 of this embodiment consists of 86.74% methane, 12.25% ethane, and 1.01% propane, and the natural gas separated by the gas-liquid separator 500 It was confirmed that the components are composed of 98.93% methane and 1.07% ethane, and that the components of the liquefied natural gas separated by the gas-liquid separator 500 are composed of 55.15% methane, 41.23% ethane, and 3.62% propane. .

The second heater 820 of this embodiment, like the first embodiment, heats the gaseous natural gas separated by the gas-liquid separator 500 to the temperature required by the second engine E2. When the second engine E2 is a DF engine, the second heater 820 heats the natural gas to approximately 0°C to 45°C. Seawater, fresh water, steam, etc. may be used as the source of the second heater 820.

Like the first embodiment, the second pressure reducing device 420 of this embodiment depressurizes the natural gas heated by the second heater 820 to the pressure required by the second engine E2. When the second engine (E2) is a DF engine, the second pressure reducing device 420 of this embodiment can depressurize natural gas to a pressure of approximately 6.5 bar. Natural gas heated by the second heater 820 and depressurized by the second pressure reducing device 420 is supplied as fuel to the second engine E2.

In Figure 3, it is shown that the second heater 820 is installed at the rear end of the gas-liquid separator 500, and the second pressure reducing device 420 is installed at the rear end of the second heater 820. However, the fuel of the marine engine of this embodiment According to the supply system, as in the first embodiment, a second pressure reducing device 420 is installed behind the gas-liquid separator 500, and a second heater 820 is installed behind the second pressure reducing device 420, After the gaseous natural gas separated by the separator 500 is decompressed to the pressure required by the second engine E2 by the second decompression device 420, the natural gas is decompressed by the second heater 820 to the second engine E2. (E2) may be heated to the required temperature.

The liquefied natural gas supply system of this embodiment, like the first embodiment, may further include a first pump 610 installed inside the storage tank (T) to discharge the liquefied natural gas stored in the storage tank (T). there is.

The first pump 610 of this embodiment, like the first embodiment, is installed at the bottom near the bottom of the storage tank (T), and is based on the size of the storage tank (T), the pressure drop of the pipe, and the liquefied natural gas to be supplied. Discharge pressure and discharge flow rate are determined depending on the gas flow rate, etc.

Figure 4 is a schematic diagram of a fuel supply system for a marine engine according to a second preferred embodiment of the present invention.

Referring to FIG. 4, the fuel supply system for the marine engine of this embodiment, like the first embodiment, includes a boil-off gas supply system that supplies boil-off gas discharged from the storage tank (T) to the engines (E1 and E2), It includes a liquefied natural gas supply system that supplies the liquefied natural gas inside the storage tank (T) to the engines (E1 and E2).

However, unlike the first embodiment, the fuel supply system for the marine engine of this embodiment further includes a re-liquefaction system for re-liquefying excess boil-off gas remaining after being used as fuel for the engines E1 and E2.

The storage tank (T), which supplies boil-off gas and liquefied natural gas to the fuel supply system of the marine engine of this embodiment, may be a membrane tank or Type C tank, as in the first embodiment, and the installation location and capacity It can be selected depending on the tank, and it is preferable to use a membrane tank.

The boil-off gas supply system of this embodiment, like the first embodiment, includes a multi-stage compressor 200, and the liquefied natural gas supply system of this embodiment, like the first embodiment, includes a second pump 620, 2 It includes a heat exchanger 120, a vaporizer 700, a gas-liquid separator 500, a second heater 820, and a second pressure reducing device 420.

Additionally, the reliquefaction system of this embodiment includes a first heat exchanger 110 and a first pressure reducing device 410.

However, unlike the first embodiment, the liquefied natural gas supply system of this embodiment further includes a third heat exchanger 130 and does not include the first heater 810.

For convenience, the multi-stage compressor 200 is described as a configuration belonging to the boil-off gas supply system, and the gas-liquid separator 500 is explained as a configuration belonging to the liquefied natural gas supply system. However, the boil-off gas discharged from the storage tank T is a multi-stage compressor ( 200), the first heat exchanger 110, and the first pressure reducing device 410, some or all of it is re-liquefied, and the re-liquefied liquefied natural gas and the boil-off gas remaining in the gaseous state are separated from the gas-liquid separator 500. Since they are separated by , the multi-stage compressor 200 and the gas-liquid separator 500 can be understood as a configuration that also belongs to the re-liquefaction system.

The multi-stage compressor 200 of this embodiment, like the first embodiment, compresses the boil-off gas discharged from the storage tank (T) in multiple stages, and includes a plurality of compressors (210, 220, 230, 240, 250) and a rear end of the compressor. It includes a compressor and a plurality of coolers (310, 320, 330, 340, 350) installed alternately. In Figure 4, a multi-stage compressor that compresses boil-off gas in five stages by five compressors and five coolers is shown as an example, but the present invention is not limited thereto. Additionally, the multi-stage compressor 200 of this embodiment may include one or more recirculation lines, like the first embodiment.

According to the fuel supply system for the marine engine of this embodiment, like the first embodiment, the boil-off gas compressed through all stages of the multi-stage compressor 200 is sent to the first engine (E1), and the boil-off gas of the multi-stage compressor 200 The evaporative gas compressed through only a few stages is branched in the middle (L3 line) and sent to the second engine (E2).

In Figure 4, it is shown as an example that evaporative gas compressed by three of the five compressors (210, 220, and 230) is partially branched and sent to the second engine (E2), but the present invention is not limited thereto. The first engine (E1) may be a ME-GI engine, and the second engine (E2) may be a DF engine.

The second pump 620 of this embodiment, like the first embodiment, compresses the liquefied natural gas discharged from the storage tank (T) to the required pressure of the first engine (E1). When the first engine (E1) is a ME-GI engine, the second pump 620 compresses the liquefied natural gas at a pressure of approximately 300 bar, and the liquefied natural gas compressed by the second pump 620 is approximately It can be -154℃, 300 bar. Additionally, the second pump 620 of this embodiment may be of the piston type, and the flow rate may be adjusted by adjusting the rotation speed.

Like the first embodiment, the second heat exchanger 120 of this embodiment uses liquefied natural gas compressed by the second pump 620 after being discharged from the storage tank (T) as a refrigerant, and uses the gas-liquid separator 500 as a refrigerant. The separated liquefied natural gas is cooled by heat exchange.

The liquefied natural gas separated by the gas-liquid separator 500 of this embodiment and then cooled by the second heat exchanger 120 may be approximately -154°C and is returned to the storage tank (T).

According to the fuel supply system for the marine engine of this embodiment, like the first embodiment, the liquefied natural gas returned to the storage tank (T) can be additionally cooled by the second heat exchanger 120, so the storage tank ( T) It is possible to prevent internal temperature rise and suppress the generation of evaporative gas inside the storage tank (T).

In addition, the liquefied natural gas discharged from the storage tank (T) and compressed by the second pump 620 and then used as a refrigerant in the second heat exchanger 120 is, like the first embodiment, the second heat exchanger ( Since it is heated by 120) and then sent to the vaporizer 700, it can be vaporized using less heat source than if it is sent directly to the vaporizer 700, making it efficient.

4 shows that the second heat exchanger 120 is installed at the rear end of the second pump 620. However, according to the fuel supply system for the marine engine of this embodiment, like the first embodiment, the second pump 620 is installed at the rear of the second heat exchanger 120, and the liquefied natural gas discharged from the storage tank (T) may be used as a refrigerant in the second heat exchanger 120 and then compressed by the second pump 620. .

The third heat exchanger 130 of this embodiment uses the fluid (L7 line) discharged from the storage tank (T) and passed through the second pump 620 and the second heat exchanger 120 as a refrigerant, and uses the vaporizer (700) as a refrigerant. ) and then partially branched natural gas (L8 line) is cooled.

In order to increase the methane number by separating heavy hydrocarbons from natural gas, natural gas must be cooled to approximately -120°C or lower. According to the fuel supply system for the marine engine of this embodiment, natural gas is After cooling to -120°C or lower, it is supplied to the gas-liquid separator (500).

In addition, the fluid sent to the third heat exchanger 130 after being used as a refrigerant in the second heat exchanger 120 is further heated by the third heat exchanger 120 and then sent to the vaporizer 700, so it is immediately sent to the vaporizer 700. It is efficient because it can be vaporized using fewer heat sources than sending it to the vaporizer 700 or passing only the second heat exchanger 120 and then sending it to the vaporizer 700.

The vaporizer 700 of this embodiment vaporizes the fluid that has passed through the second pump 620, the second heat exchanger 120, and the third heat exchanger 120 after being discharged from the storage tank T. A portion of the natural gas vaporized by the vaporizer 700 is supplied as fuel to the first engine E1 (L9 line), and the remainder (L8 line) is supplied to the third heat exchanger 130.

The natural gas vaporized by the vaporizer 700 of this embodiment may be approximately -45°C, and like the first embodiment, glycol water heated by steam, seawater, or recovered waste heat is used as the heat source. ), etc. can be used.

The first heat exchanger 110 of this embodiment heat exchanges the partially branched boil-off gas (L5 line) after being compressed through all stages of the multi-stage compressor 200 and the boil-off gas discharged from the storage tank (T) with a refrigerant. Allow to cool. Among the evaporative gases discharged from the storage tank (T), the surplus evaporative gas that is not supplied to the first engine (E1) or the second engine (E2) is supplied to the first heat exchanger (110) and undergoes a re-liquefaction process. will be.

The first pressure reducing device 410 of this embodiment expands the fluid (L5 line) compressed by the multi-stage compressor 200 and then cooled by the first heat exchanger 110.

The boil-off gas that has undergone a compression process by the multi-stage compressor 200, a cooling process by the first heat exchanger 110, and an expansion process by the first decompression device 410 is partially or entirely re-liquefied.

The boil-off gas compressed through all stages of the multi-stage compressor 200 of this embodiment may be at approximately 300 bar and 45°C, and the boil-off gas at approximately 300 bar and 45°C is cooled by the first heat exchanger 110. can be cooled to approximately -120°C, and the fluid at approximately -120°C can be expanded by the first pressure reducing device 410 and cooled to approximately -129°C.

The gas-liquid separator 500 of this embodiment separates gaseous natural gas and liquid liquefied natural gas from the fluid (L8 line) vaporized by the vaporizer 700 and then cooled by the third heat exchanger 130. Let's do it.

In addition, the gas-liquid separator 500 of this embodiment converts the fluid (L5 line) that has passed through the multi-stage compressor 200, the first heat exchanger 110, and the first pressure reducing device 410 into re-liquefied liquefied natural gas. and evaporated gas remaining in gaseous state.

That is, the fluid (L8 line) vaporized by the vaporizer 700 and then cooled by the third heat exchanger 130, the multi-stage compressor 200, the first heat exchanger 110, and the first pressure reducing device 410 ) After the fluid (L5 line) that has passed through is mixed in the gas-liquid separator 500, the mixed fluid is separated into liquefied natural gas and natural gas. The internal pressure of the gas-liquid separator 500 may be approximately 2.1 bar, and the liquefied natural gas and natural gas separated by the gas-liquid separator 500 may be approximately -129°C.

According to the fuel supply system for a marine engine of this embodiment, as in the first embodiment, the liquefied natural gas separated by the gas-liquid separator 500 is cooled by the second heat exchanger 120 and then stored in the storage tank (T). is returned to

However, according to the fuel supply system for the marine engine of this embodiment, unlike the first embodiment, not all of the gaseous natural gas separated by the gas-liquid separator 500 is sent to the second heater 820, Some are sent to the second heater 820, and the rest are sent between the first heat exchanger 110 and the multi-stage compressor 200.

The natural gas separated by the gas-liquid separator 500 of this embodiment and then sent between the first heat exchanger 110 and the multi-stage compressor 200 is discharged from the storage tank T and then used as a refrigerant in the first heat exchanger 110. It combines with the boil-off gas used and is supplied to the multi-stage compressor (200).

In Figure 4, it is shown that part of the natural gas separated by the gas-liquid separator 500 is sent between the first heat exchanger 110 and the multi-stage compressor 200, but according to the fuel supply system for the marine engine of this embodiment, , part of the natural gas separated by the gas-liquid separator 500 may be sent between the storage tank (T) and the first heat exchanger (110).

When part of the natural gas separated by the gas-liquid separator 500 of this embodiment is sent between the storage tank (T) and the first heat exchanger 110, the natural gas separated by the gas-liquid separator 500 is stored in the storage tank ( It is combined with the boil-off gas discharged from T), used as a refrigerant in the first heat exchanger 110, and then supplied to the multi-stage compressor 200.

The liquefied natural gas separated by the gas-liquid separator 500 of this embodiment has a high heavy hydrocarbon content, and the natural gas separated by the gas-liquid separator 500 has a high methane content. According to the fuel supply system for the marine engine of this embodiment, as in the first embodiment, natural gas with a high methane content separated by the gas-liquid separator 500 can be supplied to the second engine E2, so that the second engine E2 The knocking phenomenon of (E2) can be prevented.

As a result of simulation by HYSYS, the fluid supplied to the gas-liquid separator 500 of this embodiment consists of 86.74% methane, 12.25% ethane, and 1.01% propane, and the natural gas separated by the gas-liquid separator 500 It was confirmed that the components were composed of 99.76% methane and 0.24% ethane, and that the components of the liquefied natural gas separated by the gas-liquid separator 500 were composed of 84.43% methane, 14.38% ethane, and 1.19% propane. .

The second heater 820 of this embodiment, like the first embodiment, heats the gaseous natural gas separated by the gas-liquid separator 500 to the temperature required by the second engine E2. When the second engine E2 is a DF engine, the second heater 820 heats the natural gas to approximately 0°C to 45°C. Seawater, fresh water, steam, etc. may be used as the source of the second heater 820.

Like the first embodiment, the second pressure reducing device 420 of this embodiment depressurizes the natural gas heated by the second heater 820 to the pressure required by the second engine E2. When the second engine (E2) is a DF engine, the second pressure reducing device 420 of this embodiment can depressurize natural gas to a pressure of approximately 6.5 bar. Natural gas heated by the second heater 820 and decompressed by the second pressure reducing device 420 is supplied as fuel to the second engine E2.

In Figure 4, it is shown that the second heater 820 is installed at the rear end of the gas-liquid separator 500, and the second pressure reducing device 420 is installed at the rear end of the second heater 820. However, the fuel of the marine engine of this embodiment According to the supply system, as in the first embodiment, a second pressure reducing device 420 is installed behind the gas-liquid separator 500, and a second heater 820 is installed behind the second pressure reducing device 420, After the gaseous natural gas separated by the separator 500 is decompressed to the pressure required by the second engine E2 by the second decompression device 420, the natural gas is decompressed by the second heater 820 to the second engine E2. (E2) may be heated to the required temperature.

The liquefied natural gas supply system of this embodiment, like the first embodiment, may further include a first pump 610 installed inside the storage tank (T) to discharge the liquefied natural gas stored in the storage tank (T). there is.

The first pump 610 of this embodiment, like the first embodiment, is installed at the bottom near the bottom of the storage tank (T), and is based on the size of the storage tank (T), the pressure drop of the pipe, and the liquefied natural gas to be supplied. Discharge pressure and discharge flow rate are determined depending on the gas flow rate, etc.

It is obvious to those skilled in the art that the present invention is not limited to the above embodiments and can be implemented with various modifications or variations without departing from the technical gist of the present invention. will be.

T: Storage tank L1, L2: Recirculation line
E1, E2: Engine 110, 120, 130: Heat exchanger
200: multi-stage compressor 210, 220, 230, 240, 250: compressor
310, 320, 330, 340, 350: Cooler 410, 420: Pressure reducing device
500: gas-liquid separator 610, 620: pump
700: vaporizer 810, 820: heater

Claims (19)

A multi-stage compressor that compresses the boil-off gas discharged from the storage tank in multiple stages;
A second pump that compresses the liquefied natural gas discharged from the storage tank;
A second heat exchanger that cools the liquefied natural gas discharged from the storage tank by heat-exchanging the liquefied natural gas returned to the storage tank with a refrigerant;
A vaporizer that vaporizes liquefied natural gas used as a refrigerant in the second heat exchanger;
A first heater that heats the remaining liquefied natural gas that is not sent to the vaporizer among the liquefied natural gas used as a refrigerant in the second heat exchanger; and
It includes a gas-liquid separator that is heated by the first heater and separates partially vaporized natural gas and liquefied natural gas remaining in a liquid state,
The natural gas separated by the gas-liquid separator is supplied to the second engine,
The liquefied natural gas separated by the gas-liquid separator is cooled by the second heat exchanger and then returned to the storage tank,
The natural gas separated by the gas-liquid separator has a higher methane content compared to the fluid supplied to the gas-liquid separator,
The liquefied natural gas separated by the gas-liquid separator has a higher content of heavy hydrocarbons compared to the fluid supplied to the gas-liquid separator,
It further includes a second heater that heats the natural gas separated by the gas-liquid separator to a temperature required by the second engine and a second pressure reducing device that reduces the pressure to the pressure required by the second engine,
The natural gas separated by the gas-liquid separator is heated by the second heater and then supplied to the second engine,
The second pressure reducing device is installed between the gas-liquid separator and the second heater or between the second heater and the second engine,
A fuel supply system for a marine engine, wherein the second engine is an engine that requires a methane number above a certain value. delete delete In claim 1,
The second engine is a DF engine,
The second heater heats natural gas to 0°C to 45°C,
The second pressure reducing device is a fuel supply system for a marine engine that depressurizes natural gas to 6.5 bar. In claim 1,
A fuel supply system for a marine engine, further comprising a first pump installed inside the storage tank to discharge liquefied natural gas. In claim 1,
The second heat exchanger is installed at a rear end of the second pump and uses liquefied natural gas compressed by the second pump as a refrigerant. In claim 1,
The second pump is installed at a rear end of the second heat exchanger and compresses liquefied natural gas used as a refrigerant in the second heat exchanger. In claim 1,
The boil-off gas compressed through all stages of the multi-stage compressor is sent to the first engine, and the boil-off gas compressed through only some stages of the multi-stage compressor is branched in the middle and sent to the second engine, supplying fuel to the marine engine. system. In claim 1,
Natural gas vaporized by the vaporizer is supplied to the first engine,
The second pump is a fuel supply system for a marine engine that compresses liquefied natural gas to the required pressure of the first engine. In claim 5,
The first pump is a fuel supply system for a marine engine, which is installed at the lower part of the storage tank. In claim 8 or claim 9,
The first engine is the ME-GI engine,
The second pump is a fuel supply system for a marine engine that compresses liquefied natural gas to 300 bar. The method according to any one of claims 1, 4 to 10,
The multi-stage compressor includes a plurality of compressors and a plurality of coolers,
The fuel supply system for a marine engine, wherein the plurality of coolers are respectively installed at a rear end of the plurality of compressors, and the plurality of compressors and the plurality of coolers are installed alternately. In claim 12,
The multi-stage compressor is a fuel supply system for a marine engine that compresses boil-off gas in five stages, including five compressors and five coolers. 1) Heating the liquefied natural gas discharged from the storage tank;
2) separating gas and liquid from the fluid heated in step 1);
3) cooling the liquefied natural gas separated in step 2) by exchanging heat in a second heat exchanger using the liquefied natural gas discharged from the storage tank as a refrigerant, and then returning it to the storage tank; and
4) supplying the natural gas separated in step 2) to the second engine;
The fluid used as a refrigerant in the second heat exchanger in step 3) is heated in step 1),
The natural gas separated in step 2) has a higher methane content than the fluid before gas-liquid separation,
The liquefied natural gas separated in step 2) has a higher content of heavy hydrocarbons than the fluid before gas-liquid separation,
Heating the natural gas separated in step 2) to a temperature required by the second engine by a second heater and then supplying it to the second engine; and
Further comprising depressurizing the natural gas separated in step 2) to the pressure required by the second engine at the front or rear end of the second heater and then supplying it to the second engine,
A fuel supply method for a marine engine, wherein the second engine is an engine that requires a methane number above a certain value. In claim 14,
A fuel supply method for a marine engine, further comprising compressing the boil-off gas discharged from the storage tank to the pressure required by the first engine at the front or rear end of the second heat exchanger. In claim 15,
5) further comprising the step of partially branching and vaporizing the fluid used as the refrigerant of the second heat exchanger in step 3),
A fuel supply method for a marine engine, wherein the natural gas vaporized in step 5) is supplied to the first engine. delete delete The liquefied natural gas discharged from the storage tank is heated through the second heat exchanger and the first heater and then separated into gas and liquid,
Natural gas with an increased methane number after gas-liquid separation is supplied to the DF engine.
The gas-liquid separated liquefied natural gas is cooled by heat exchanging the liquefied natural gas discharged from the storage tank with a refrigerant and then returned to the storage tank,
The natural gas whose methane number has increased due to the gas-liquid separation is secondarily heated through a second heater,
A method of supplying fuel to a marine engine, wherein the pressure is reduced to the pressure required by the DF engine at the front or rear end of the second heater and then supplied to the DF engine.

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