KR102589457B1 - Fuel Supply System And Method Ammonia Fueled Ship - Google Patents

Abstract

A ship's ammonia fuel supply system and method are disclosed. The ammonia fuel supply system for ships of the present invention includes a liquefied gas storage tank for storing liquefied gas to be supplied as fuel for engines on ships; An ammonia storage tank for storing ammonia to be supplied as fuel for the engine; and a mixing unit that supplies fuel to the engine from the liquefied gas storage tank and the ammonia storage tank, wherein the ammonia storage tank is provided inside the liquefied gas storage tank, and the liquefied gas of the liquefied gas storage tank is used. It is characterized by cooling the ammonia storage tank.

Description

Ammonia fuel supply system and method for ships {Fuel Supply System And Method Ammonia Fueled Ship}

The present invention relates to an ammonia fuel supply system and method for ships, and more specifically, to a liquefied gas storage tank by providing an ammonia storage tank inside the liquefied gas storage tank in a ship equipped with an engine supplied with liquefied gas and ammonia as fuel. It relates to a ship's ammonia fuel supply system and method that prevents the generation of ammonia evaporation gas by cooling the ammonia storage tank with liquefied gas, and supplies fuel to the engine from the liquefied gas storage tank and the ammonia storage tank through a mixing unit.

As the global warming phenomenon intensifies, efforts are being made to reduce greenhouse gas emissions around the world, and as the 1997 Kyoto Protocol, which included obligations for developed countries to reduce greenhouse gases, expires in 2020, the event held in Paris, France in December 2015 The 195 parties participating in the Paris Climate Change Accord, which was adopted at the 21st United Nations Framework Convention on Climate Change and came into effect in November 2016, are making various efforts with the goal of reducing greenhouse gases.

Along with this global trend, interest in renewable energy (or renewable energy) such as wind power, solar power, solar heat, bioenergy, tidal power, and geothermal heat as a pollution-free energy that can replace fossil fuels and nuclear power is increasing, and various technologies are being developed. I'm losing.

Liquefied gases, including liquefied natural gas, can remove or reduce air pollutants during the liquefaction process, so they can be viewed as eco-friendly fuels that emit fewer air pollutants during combustion. Accordingly, the consumption of liquefied gases such as Liquefied Natural Gas (LNG) and LPG (Liquefied Petroleum Gas) has recently been rapidly increasing worldwide. Liquefied gas, which is made by liquefying gas at low temperature, has a much smaller volume than gas, so it has the advantage of increasing storage and transportation efficiency.

Liquefied natural gas (LNG) is a colorless and transparent liquid obtained by liquefying natural gas containing methane as a main component by cooling it to about -162°C, and has a volume of about 1/600 of that of natural gas. Therefore, when natural gas is liquefied and transported, it can be transported very efficiently.

Liquefied petroleum gas (LPG) has different liquefaction temperatures depending on its composition, but in the case of petroleum gas mainly containing propane, it is liquefied at a low temperature of about -42℃ at normal pressure, up to a temperature of about 45℃ at 18 bar, and 20℃ at 7 bar. It can be stored in liquid state up to ℃.

Meanwhile, conventional LPG carriers, etc., adopt a fuel supply system that uses relatively inexpensive heavy oil such as bunker C oil as propulsion fuel for ships. This heavy oil fuel supply system has the international exhaust gas emissions associated with the use of heavy oil fuel. Due to strengthened regulations, a separate low-sulfur heavy fuel fuel tank (LSHFO tank) had to be installed, and the demand for an eco-friendly fuel supply system that meets international environmental regulation standards has increased.

Recently, the application of fuel supply systems that use LPG or LNG and boil-off gas generated therefrom as propulsion fuel has been increasing in LPG or LNG carriers, and in accordance with the strengthening of international exhaust gas emission regulations, in addition to LPG or LNG carriers, general ships also use LNG. The number of ships using propulsion fuel is increasing.

Representative marine engines that can use LNG as fuel include gas fuel engines such as DFDE, X-DF engines, and ME-GI engines.

DFDE consists of a 4-stroke cycle and adopts the Otto Cycle, which injects natural gas with a relatively low pressure of about 5.5 barg into the combustion air inlet and compresses it as the piston rises.

The X-DF engine consists of a two-stroke engine, uses natural gas of about 15 barg as fuel, and adopts the Otto cycle.

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

However, although LNG and LPG are evaluated as eco-friendly fuels compared to other fossil fuels previously used as ship fuels, they still produce carbon dioxide when burned, and ships that use them as fuel still emit carbon dioxide during operation.

IMO (International Maritime Organization), a UN specialized organization established to internationally unify shipping routes, traffic rules, port facilities, etc., also plans to reduce greenhouse gases by 50% in 2050 compared to 2008 and reduce greenhouse gases by 100% by 2100. % reduction (GHG Zero Emission) is proposed as the goal, and regulations in each country and region are expected to be strengthened accordingly.

According to EEDI (Energy Efficiency Design Index), a mandatory carbon dioxide reduction regulation applied by IMO to new ships, the initial EEDI announcement called for a 10% reduction in carbon dioxide emissions in 2015 based on carbon dioxide emissions from 2013 to 2015. EEDI Phase 1 was applied, and it was planned to apply Phase 3 in 2025 by strengthening and applying one step every five years. However, for LPG carriers, EEDI Phase 3 will be applied early from 2022, two years after applying EEDI Phase 2. It is being done. As regulations on carbon dioxide emissions from ships are rapidly being strengthened, it may be difficult to achieve carbon dioxide emissions regulations in the future by using only LNG or LPG as fuel.

Accordingly, various studies are being conducted on eco-friendly marine fuels that can reduce carbon dioxide emissions, and recently, technologies for marine engines that can use ammonia as fuel along with fuels such as LNG or LPG are being researched and developed.

Ammonia (NH ₃ ) is a substance in which three hydrogens are bonded to one nitrogen. It can form strong hydrogen bonds between molecules, making it easy to liquefy. It has a boiling point of -33.34°C and a melting point of -77.73°C at normal pressure.

This ammonia is easier to store than LNG, and although it is slightly lower in SPECIFIC ENERGY and ENERGY DENSITY compared to existing HFO, it does not emit any carbon dioxide, so it is attracting attention as an eco-friendly marine fuel that can respond to the trend of strengthening international greenhouse gas emission standards.

The present invention seeks to propose a fuel supply system that can supply fuel to ship engines more effectively by supplying ammonia as ship fuel in response to the strengthening of carbon dioxide emission standards, and by compensating for the problem of lower combustion speed and calorific value compared to existing ship fuel. .

According to one aspect of the present invention for solving the above-described problem, a liquefied gas storage tank for storing liquefied gas to be supplied as fuel for an engine in a ship;

An ammonia storage tank for storing ammonia to be supplied as fuel for the engine; and

A mixing unit that supplies fuel from the liquefied gas storage tank and the ammonia storage tank to the engine,

The ammonia storage tank is provided inside the liquefied gas storage tank, and an ammonia fuel supply system for a ship is provided, wherein the ammonia storage tank is cooled with the liquefied gas of the liquefied gas storage tank.

Preferably, an ammonia supply line connected from the ammonia storage tank to the mixing unit; A liquefied gas supply line connected from the liquefied gas storage tank to the mixing unit; A first flow meter provided in the ammonia supply line; A second flow meter provided in the liquefied gas supply line; And a controller that controls the flow rate of ammonia and liquefied gas supplied to the mixing unit through the first and second flow meters according to the amount of fuel required by the engine and the carbon dioxide emission standards of the ship.

Preferably, the liquefied gas storage tank further includes a first insulation portion provided to surround the ammonia storage tank inside the liquefied gas storage tank, and the first insulation portion may be provided in a watertight structure to prevent leakage of the liquefied gas and ammonia. there is.

Preferably, an ammonia transfer pump is provided in the ammonia storage tank to transfer ammonia; An ammonia boost pump provided in the ammonia supply line and compressing the ammonia transferred from the ammonia transfer pump to the pressure required by the engine; And an ammonia heater that heats the ammonia compressed in the ammonia boost pump to the temperature required by the engine and transfers it to the mixing unit.

Preferably, a liquefied gas transfer pump provided in the liquefied gas storage tank to transfer liquefied gas; A liquefied gas boost pump provided in the liquefied gas supply line and compressing the liquefied gas transferred from the liquefied gas transfer pump to the pressure required by the engine; And it may further include a liquefied gas heater that heats the liquefied gas compressed in the liquefied gas boost pump to a temperature required by the engine and transfers it to the mixing unit.

Preferably, a boil-off gas supply line that supplies boil-off gas generated in the liquefied gas storage tank to the mixing unit; A compressor provided in the boil-off gas supply line to compress the boil-off gas to the pressure required by the engine; an evaporative gas heater that heats the evaporative gas compressed in the compressor to a temperature required by the engine and transfers it to the mixing unit; And it may further include a third flow meter provided downstream of the boil-off gas heater in the boil-off gas supply line.

Preferably, a return line for discharging unconsumed fuel or vented fuel from the engine; and a return tube provided in the return line to receive fuel discharged from the engine, wherein the fuel discharged through the return tube can be recovered at the front of the compressor of the boil-off gas supply line or discharged overboard.

Preferably, the liquefied gas is LNG, and a second insulation portion surrounding the liquefied gas storage tank may be provided on the outside of the liquefied gas storage tank.

According to another aspect of the present invention, in a ship equipped with an engine supplied with liquefied gas and ammonia as fuel,

Fuel is supplied to the engine through a mixing unit from a liquefied gas storage tank that stores liquefied gas to be supplied as fuel for the engine and an ammonia storage tank that stores ammonia,

A method of supplying ammonia fuel to a ship is characterized in that the ammonia storage tank is provided inside the liquefied gas storage tank, and the ammonia storage tank is cooled with the liquefied gas of the liquefied gas storage tank to prevent the generation of ammonia evaporation gas. provided.

Preferably, the flow rate of ammonia and liquefied gas supplied to the mixing unit can be controlled from the controller according to the amount of fuel required by the engine and the carbon dioxide emission standards of the ship.

Preferably, a first insulation part is provided inside the liquefied gas storage tank to surround the ammonia storage tank, and the first insulation part may be provided in a watertight structure to prevent leakage of the liquefied gas and ammonia.

In the present invention, a mixing unit is provided to supply liquefied gas and ammonia from the liquefied gas storage tank and the ammonia storage tank to the engine fuel through the mixing unit, so that the liquefied gas and ammonia are mixed and supplied to solve the problem of low combustion speed and calorific value of ammonia fuel. can be solved. In addition, by adjusting the supply of ammonia fuel, an eco-friendly fuel, according to the carbon dioxide emission standards applied to ships, it is possible to reduce greenhouse gas emissions during ship operation and respond to the strengthening of regulatory standards set by international conventions.

In particular, by providing an ammonia storage tank inside the liquefied gas storage tank, the ammonia storage tank can be cooled using the cold heat of the liquefied gas in the liquefied gas storage tank to prevent the generation of evaporation gas due to evaporation of ammonia.

Figure 1 schematically shows an ammonia fuel supply system for a ship according to an embodiment of the present invention.

In order to fully understand the operational advantages of the present invention and the objectives achieved by practicing the present invention, reference should be made to the accompanying drawings illustrating preferred embodiments of the present invention and the contents described in the accompanying drawings.

Hereinafter, the structure and operation of a preferred embodiment of the present invention will be described in detail with reference to the attached drawings. Here, in adding reference numerals to components in each drawing, it should be noted that identical components are indicated with the same reference numerals as much as possible, even if they are shown in different drawings.

Hereinafter, the ship in the present invention refers to all types of ships equipped with an engine that can use ammonia as fuel for the ship's engine. Representative examples include LPG carrier (LNG Carrier), LNG carrier (LNG Carrier), liquid hydrogen carrier, and liquid hydrogen carrier. Ships with self-propelled capabilities such as carriers, ammonia carriers, container carriers, crude oil carriers, bulk carriers for minerals or grains, and Ro-Ro (Roll on/Roll off) ships, as well as ships that do not have propulsion capabilities but are floating at sea. Offshore structures under construction may also be included.

The engine described later includes both a ship's propulsion engine and a power generation engine, and can be supplied with ammonia together with other marine fuels such as LNG, LPG, HFO, and Diesel Oil, or with ammonia alone. This meaning includes, and in the following, an engine supplied with LNG and ammonia, which are representative marine engine fuels, will be explained as an example.

Figure 1 schematically shows an ammonia fuel supply system for a ship according to an embodiment of the present invention.

As shown in Figure 1, the fuel supply system of this embodiment is a system that supplies ammonia and liquefied gas as fuel for the ship engine (E), and includes a liquefied gas storage tank (LT) that stores the liquefied gas to be supplied as fuel for the engine. ), an ammonia storage tank (AT) that stores ammonia to be supplied as fuel for the engine, a liquefied gas storage tank, and a mixing unit 300 that supplies fuel from the ammonia storage tank to the engine.

In this embodiment, the ammonia storage tank (AT) is provided inside the liquefied gas storage tank (LT) to cool the ammonia storage tank through the cold heat of the liquefied gas in the liquefied gas storage tank to maintain a low temperature within a certain range. It is characteristic.

In the case of LNG, the temperature is low at around -163°C at atmospheric pressure, so in this embodiment, an ammonia storage tank (AT) is placed inside the liquefied gas storage tank (LT) where the extremely low temperature LNG is stored, so that the ammonia storage tank is kept at a certain temperature using LNG cold heat. Hereinafter, evaporation of ammonia stored in the ammonia storage tank can be prevented by maintaining a low temperature of, for example, -30°C or lower. By maintaining a low temperature in this way to prevent evaporation of ammonia in the ammonia storage tank, the pressure of the ammonia storage tank can be safely maintained without installing separate equipment for processing ammonia evaporation gas.

This storage tank configuration method of this embodiment can also be applied to the storage of LPG. Since LPG has a low temperature of about -42℃ at atmospheric pressure, the LPG storage tank is installed inside the liquefied gas storage tank where LNG is stored in ships that supply LNG and LPG as engine fuel, and LNG refrigeration is provided like the ammonia storage tank mentioned above. You can prevent LPG vaporization by maintaining low temperature.

Meanwhile, when cryogenic LNG and the ammonia storage tank come into direct contact, the ammonia in the ammonia storage tank may freeze, crystallize, or solidify. To prevent this and to store ammonia in a liquid state, an ammonia storage tank is installed inside the liquefied gas storage tank to surround the ammonia storage tank. A first insulation part (ISa) is provided, and the ammonia storage tank is kept warm so that it is not directly exposed to the extremely low temperature of LNG. The first insulation part may be provided with a watertight structure to prevent mutual leakage of liquefied gas and ammonia.

A second insulation portion (ISb) surrounding the liquefied gas storage tank is provided on the outside of the liquefied gas storage tank to prevent heat intrusion into the liquefied gas storage tank.

As shown in FIG. 1, an ammonia supply line (ASL) is connected from the ammonia storage tank (AT) to the mixing unit 300 to supply fuel to the engine, and the ammonia supply line (ASL) is connected from the liquefied gas storage tank (LT) to the mixing unit 300. The liquefied gas supply line (LL) is connected to this.

The ammonia storage tank is equipped with an ammonia transfer pump (AP) that transfers ammonia along the ammonia supply line, and an ammonia boost pump that compresses the ammonia transferred from the ammonia transfer pump along the ammonia supply line (ASL) to the pressure required by the engine. (100) and an ammonia heater (110) are provided to heat the ammonia compressed in the ammonia boost pump to the temperature required by the engine and transfer it to the mixing unit.

In addition, the liquefied gas storage tank is equipped with a liquefied gas transfer pump (LP) that transfers liquefied gas, and the liquefied gas supply line (LL) is equipped with a liquefied gas that compresses the liquefied gas transferred from the liquefied gas transfer pump to the pressure required by the engine. A boost pump 200 and a liquefied gas heater 210 are provided to heat the liquefied gas compressed in the liquefied gas boost pump to the temperature required by the engine and transfer it to the mixing unit.

The ammonia transfer pump and the liquefied gas transfer pump are pumps that pump ammonia and LNG from the tank and transfer them to the outside of the tank, respectively. They can be equipped with a VFD (Variable Frequency Drive) pump that can control the flow rate of the transferred ammonia and LNG. It can be provided with a submersible pump.

Ammonia and LNG transferred from each storage tank through a transfer pump can be compressed and heated to the pressure and temperature required by the engine through a boost pump and heater, mixed in the mixing unit 300, and supplied to the engine.

For example, in the case of the MAN LGIA engine, LNG and ammonia can be supplied in a gaseous state at 25 to 45 ° C.

Compared to LNG, ammonia has a low combustion rate of about 20% and a calorific value of about 50%, and ignition delay may occur when supplied alone. In this embodiment, ammonia and LNG are compressed and vaporized respectively and mixed in a mixing unit to provide engine fuel. By supplying , the problems of ignition delay, low combustion speed and calorific value of ammonia fuel can be solved.

The ratio of ammonia and LNG supplied to the engine through the mixing unit can be adjusted according to the carbon dioxide emission standards applied to ships.

A first flow meter (FM1) is provided downstream of the ammonia heater 110 in the ammonia supply line (ASL), and a second flow meter (FM2) is provided downstream of the liquefied gas heater 210 in the liquefied gas supply line (LL). , the controller 350 controls the first and second flow meters (FM1, FM2) according to the amount of fuel required by the engine (E) and the carbon dioxide emission standards applied to the ship, and flows to the engine (E) through the mixing unit 300. The flow rate of supplied ammonia and liquefied gas can be adjusted.

For example, if ammonia is mixed at a rate of 20% of LNG's calorific value and supplied as engine fuel for combustion, carbon dioxide emissions can be reduced by about 20% compared to when LNG is burned alone.

In this way, in this embodiment system, considering the amount of fuel required by the engine and the carbon dioxide emission standards applied to ships at each time or in the operating sea, the controller controls each flow meter to adjust the fuel supply amount and ratio of ammonia and LNG to the ship. While reducing greenhouse gas emissions, we can flexibly respond to carbon dioxide regulation standards set by international agreements.

Boil-off gas generated from LNG stored in a liquefied gas storage tank can also be treated by supplying it as fuel for the engine.

For this purpose, a boil-off gas supply line (GL) that supplies boil-off gas from the liquefied gas storage tank (LT) to the mixing unit 300 is connected, and a compressor (GL) that compresses the boil-off gas to the pressure required by the engine is connected to the boil-off gas supply line. 400) and an evaporative gas heater 410 that heats the evaporative gas compressed in the compressor to the temperature required by the engine and transfers it to the mixing unit. A third flow meter (FM3) is provided downstream of the boil-off gas heater in the boil-off gas supply line to control the flow rate of boil-off gas supplied to the mixing unit. The third flow meter may also be controlled by the controller 350.

Meanwhile, a return line (RL) is provided to discharge unconsumed fuel or vented fuel from the engine (E), and the return line has a return tube (500) to receive fuel discharged from the engine. It is prepared.

Gaseous fuel including LNG and ammonia discharged from the engine to the return tube 500 through the return line (RL) is recovered in front of the compressor 400 of the boil-off gas supply line (GL) and mixed with the compressor and boil-off gas heater. It can be resupplied as engine fuel through the unit. Fuel gas discharged to the return tube through the return line may be discharged overboard.

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

E: engine
LT: Liquefied gas storage tank
AT: Ammonia storage tank
ISa: first insulation section
ISb: second insulation part
ASL: Ammonia supply line
LL: Liquefied gas supply line
GL: Evaporative gas supply line
RL: return line
FM1, FM2, FM3: first to third flow meters
100: Ammonia boost pump
110: Ammonia heater
200: Liquefied gas boost pump
210: Liquefied gas heater
300: mixing unit
350: Controller

Claims (11)

A liquefied gas storage tank that stores liquefied gas to be supplied as fuel for engines on ships;
An ammonia storage tank for storing ammonia to be supplied as fuel for the engine; and
a mixing unit that supplies fuel from the liquefied gas storage tank and the ammonia storage tank to the engine; and
It includes: a first insulation portion provided to surround the ammonia storage tank inside the liquefied gas storage tank,
The ammonia storage tank is provided inside the liquefied gas storage tank, the first insulation portion is provided in a watertight structure to prevent leakage of liquefied gas and ammonia, and the ammonia storage tank is connected to the liquefied gas of the liquefied gas storage tank. A ship's ammonia fuel supply system characterized by cooling. According to clause 1,
An ammonia supply line connected from the ammonia storage tank to the mixing unit;
A liquefied gas supply line connected from the liquefied gas storage tank to the mixing unit;
A first flow meter provided in the ammonia supply line;
A second flow meter provided in the liquefied gas supply line; and
Ammonia fuel supply for a ship further comprising a controller for controlling the flow rate of ammonia and liquefied gas supplied to the mixing unit through the first and second flow meters according to the amount of fuel required by the engine and the carbon dioxide emission standards of the ship. system. delete According to clause 2,
An ammonia transfer pump provided in the ammonia storage tank to transfer ammonia;
An ammonia boost pump provided in the ammonia supply line and compressing the ammonia transferred from the ammonia transfer pump to the pressure required by the engine; and
An ammonia fuel supply system for a ship further comprising: an ammonia heater that heats the ammonia compressed in the ammonia boost pump to the temperature required by the engine and transfers it to the mixing unit. According to clause 4,
A liquefied gas transfer pump provided in the liquefied gas storage tank to transfer liquefied gas;
A liquefied gas boost pump provided in the liquefied gas supply line and compressing the liquefied gas transferred from the liquefied gas transfer pump to the pressure required by the engine; and
A liquefied gas heater for heating the liquefied gas compressed in the liquefied gas boost pump to a temperature required by the engine and transferring it to the mixing unit. According to clause 5,
A boil-off gas supply line that supplies boil-off gas generated in the liquefied gas storage tank to the mixing unit;
A compressor provided in the boil-off gas supply line to compress the boil-off gas to the pressure required by the engine;
an evaporative gas heater that heats the evaporative gas compressed in the compressor to a temperature required by the engine and transfers it to the mixing unit; and
A ship's ammonia fuel supply system further comprising: a third flow meter provided downstream of the boil-off gas heater in the boil-off gas supply line. According to clause 6,
a return line that discharges unconsumed fuel or vented fuel from the engine; and
It further includes a return tube provided in the return line to receive fuel discharged from the engine,
A ship's ammonia fuel supply system, characterized in that the fuel discharged through the return tube can be recovered at the front of the compressor of the boil-off gas supply line or discharged overboard. According to any one of claims 1, 2, and 4 to 7,
The liquefied gas is LNG,
A ship's ammonia fuel supply system, characterized in that a second insulation part surrounding the liquefied gas storage tank is provided on the outside of the liquefied gas storage tank. On ships equipped with engines supplied with liquefied gas and ammonia as fuel,
Fuel is supplied to the engine through a mixing unit from a liquefied gas storage tank that stores liquefied gas to be supplied as fuel for the engine and an ammonia storage tank that stores ammonia,
The ammonia storage tank is provided inside the liquefied gas storage tank, and a first insulation portion is provided to surround the ammonia storage tank inside the liquefied gas storage tank, wherein the first insulation portion prevents leakage of liquefied gas and ammonia. It is equipped with a watertight structure to
A method of supplying ammonia fuel to a ship, characterized in that the ammonia storage tank is cooled with the liquefied gas of the liquefied gas storage tank to prevent the generation of ammonia evaporation gas. According to clause 9,
A method of supplying ammonia fuel to a ship, characterized in that the flow rate of ammonia and liquefied gas supplied to the mixing unit is controlled by a controller according to the amount of fuel required by the engine and the carbon dioxide emission standard of the ship. delete

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