KR102594024B1 - Fuel Supply System And Method For Ship - Google Patents

Abstract

A ship fuel supply system and method are disclosed. A fuel storage tank provided on the ship and storing liquefied gas to be supplied as fuel for the ship's engines; A fuel supply line connected from the fuel storage tank to the engine to supply liquefied gas; A booster pump provided in the fuel supply line and compressing the liquefied gas to the fuel supply pressure of the engine; A fuel recovery line that recovers and recirculates unconsumed liquefied gas among the liquefied gas supplied to the engine; and a catch tank provided in the fuel recovery line to accommodate liquefied gas recovered from the engine, wherein the liquefied gas is compressed in a booster pump and supplied to the engine in a high-pressure liquid state, and recovered through the fuel recovery line. The liquefied gas is supplied to the front end of the booster pump of the fuel supply line through the catch tank.

Description

Fuel supply system and method for ship {Fuel Supply System And Method For Ship}

The present invention relates to a fuel supply system and method for a ship, and more specifically, to a fuel supply system and method for a ship that supplies liquefied gas, especially ammonia, to the ship's engine and recovers and recirculates the liquefied gas that is not consumed as fuel. will be.

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 gas such as liquefied natural gas (LNG) 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 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.

The liquefaction temperature of liquefied petroleum gas varies depending on its composition, but in the case of petroleum gas containing propane as the main ingredient, it is liquefied at a low temperature of about -42℃ at normal pressure, and at a temperature of about 45℃ at 18 bar, and at 20℃ at 7 bar. It can be saved as a state.

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.

In particular, LPG is easier to store than LNG, which is liquefied at extremely low temperatures, and does not fall significantly in SPECIFIC ENERGY and ENERGY DENSITY compared to existing HFO, and has excellent savings in SOX, NOX, CO2, and PM compared to existing HFO.

Although LNG and LPG are considered 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 such, regulations on carbon dioxide emissions are being rapidly strengthened, and in the case of LPG carriers over 15,000 DWT, if the standards of Phase 4 (40% reduction in carbon dioxide emissions) or higher are applied in the future, LPGCs using the current LPG as fuel will not be able to meet carbon dioxide emission regulations. It can be difficult.

Accordingly, various studies are being conducted on eco-friendly marine fuels that can reduce carbon dioxide emissions, and recently, technology for marine engines that can use ammonia as fuel along with fuels such as LNG or LPG is being 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 ammonia as fuel for marine engines while recovering and effectively processing unconsumed ammonia fuel from the engine.

According to one aspect of the present invention for solving the above-described problem, a fuel storage tank is provided on a ship and stores liquefied gas to be supplied as fuel for the ship's engine;

A fuel supply line connected from the fuel storage tank to the engine to supply liquefied gas;

A booster pump provided in the fuel supply line and compressing the liquefied gas to the fuel supply pressure of the engine;

A fuel recovery line that recovers and recirculates unconsumed liquefied gas among the liquefied gas supplied to the engine; and

It includes a catch tank provided in the fuel recovery line to accommodate liquefied gas recovered from the engine,

The liquefied gas is compressed in a booster pump and supplied to the engine in a high-pressure liquid state, and the liquefied gas recovered through the fuel recovery line is supplied to the front end of the booster pump of the fuel supply line through the catch tank. A fuel supply system for the ship is provided.

Preferably, a supply pump provided in the fuel supply line and transporting liquefied gas from the fuel storage tank to the booster pump; And it may further include a temperature controller provided in the fuel supply line, which receives compressed liquefied gas from the booster pump and adjusts it to the fuel supply temperature of the engine.

Preferably, a heating medium circulation line through which the heating medium supplied to the temperature controller to control the temperature of the liquefied gas circulates; a heat medium pump provided in the heat medium circulation line to circulate the heat medium; And a heat medium heat exchanger provided in the heat medium circulation line and controlling the temperature of the heat medium transferred through the heat medium pump by heat exchange with seawater or fresh water and supplying it to the temperature controller.

Preferably, a liquefied gas cooling line that cools the liquefied gas stored in the fuel storage tank and then returns it to the fuel storage tank; And a liquefied gas heat exchanger provided in the liquefied gas cooling line and receiving the heat medium that has passed through the heat medium heat exchanger to exchange heat with the liquefied gas.

Preferably, a vent line connected from the fuel storage tank to the vent mast of the ship to discharge gas from the fuel storage tank; A safety valve provided to prevent overpressure in the fuel storage tank; and a gas discharge line connected from the catch tank to the vent mast and discharging gas from the catch tank to the vent mast.

Preferably, it further includes a gas valve unit including valves that control the supply of liquefied gas between the fuel supply line and fuel recovery line and the engine, wherein the fuel supply line and fuel recovery line in the gas valve unit A double block and bleed valve may be installed to control the supply of each liquefied gas.

Preferably, the liquefied gas is ammonia, and the engine may be supplied with ammonia alone or together with other marine fuels including LNG, LPG, HFO, MGO, and Diesel Oil.

Preferably, the fuel storage tank may be provided as a pressurized tank with a design pressure of 5 to 30 barg.

According to another aspect of the present invention, the liquefied gas is compressed by the fuel supply pressure of the engine in a booster pump from a fuel storage tank that stores the liquefied gas to be supplied as fuel for the onboard engine, and supplied to the engine along the fuel supply line,

The liquefied gas is compressed in a booster pump and supplied to the engine in a high-pressure liquid state,

A fuel supply method for ships is provided, characterized in that unconsumed liquefied gas among the liquefied gas supplied to the engine is recovered through a fuel recovery line and supplied to the front of the booster pump of the fuel supply line through a catch tank for recirculation. .

Preferably, the fuel supply line is provided with a temperature controller that receives compressed liquefied gas from the booster pump and adjusts it to the fuel supply temperature of the engine. The temperature controller is provided with seawater or fresh water that circulates along the heat medium circulation line. A heat medium whose temperature is controlled by heat exchange can be supplied to control the temperature of the liquefied gas.

Preferably, the liquefied gas stored in the fuel storage tank may be supplied with a heat medium from the heat medium circulation line, cooled through heat exchange, and then returned to the fuel storage tank.

Preferably, the liquefied gas is ammonia, and the fuel storage tank may be provided as a pressurized tank with a design pressure of 5 to 30 barg.

In the present invention, ammonia, an eco-friendly fuel, is supplied as fuel for marine engines to reduce greenhouse gas emissions during ship operation and meet regulatory standards set by international conventions.

In particular, the remaining ammonia fuel that is oversupplied to the engine and not consumed by the engine is recovered and sent to the fuel supply line at the front of the booster pump through a catch tank for recirculation. Depending on the amount of high-temperature liquefied gas recirculated, the ammonia fuel is recycled at the rear of the booster pump through a temperature controller. Fuel can be supplied to the engine at the appropriate temperature required by heating or cooling.

In addition, ammonia to be supplied as engine fuel can be stored safely at room temperature by storing it in a fuel storage tank made of a pressure vessel and controlling the temperature by cooling the ammonia in the tank with a heat medium. This reduces installation costs for installing separate insulation or reliquefaction facilities, and reduces the size of facilities for fuel supply, contributing to securing space within the ship.

Figure 1 schematically shows a 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. Self-propelled capabilities such as carriers, ammonia carriers, container carriers, crude oil carriers, bulk carriers for minerals or grains, special ships such as wind turbine installation vessels, and Ro-Ro (Roll on/Roll off) ships. It may also include ships equipped with , as well as offshore structures that do not have propulsion capabilities but are floating at sea.

Engines supplied with ammonia as fuel include those supplied with ammonia as fuel together with other marine fuels such as LNG, LPG, HFO, MGO, and Diesel Oil, and those supplied with ammonia alone as fuel. Includes both propulsion engines and power generation engines. Propulsion engines and power generation engines may be provided in two or more units as needed.

Figure 1 schematically shows a 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 includes a fuel storage tank (T), which stores liquefied gas to be supplied as fuel for the engine in a ship equipped with an engine (E) supplied with liquefied gas, especially ammonia, and fuel storage. It includes a fuel supply line (SL) connected from the tank to the engine to supply liquefied gas to the engine, and a booster pump 110 provided in the fuel supply line and compressing the liquefied gas to the fuel supply pressure of the engine.

Upstream of the booster pump in the fuel supply line, a supply pump 100 is provided to transfer liquefied gas from the fuel storage tank to the booster pump, and downstream of the booster pump in the fuel supply line, compressed liquefied gas is supplied from the booster pump to fuel the engine. A temperature controller 120 is provided to control the supply temperature.

The fuel storage tank (T) may be a pressurized tank with a design pressure of 5 to 30 barg, for example, a C-Type tank with a design pressure of 25 barg. Under normal operating conditions, liquefied gas can be stored in a fuel storage tank at a room temperature of around 25°C and a pressure of around 10 barg.

Liquid ammonia transferred from the fuel storage tank (T) to the booster pump 110 at 20 to 25 barg through the supply pump 100 is further compressed to about 30 to 85 barg in the booster pump, for example, and is operated by a temperature controller. After being adjusted to a temperature of 35 to 45°C, it can be supplied to the engine in a high-pressure liquid state.

When an incompressible fluid with little or no change in volume even when pressure is applied, that is, liquid fuel, is supplied to the engine, excess fuel is supplied to the engine to respond to changes in engine load and prevent cavitation. And among the fuel supplied to the engine, the remaining fuel after being consumed is recovered upstream of the engine. For example, at an engine's MCR (Maximum Continuous Rating) of 100%, 130 liquefied gases are supplied to the engine through the fuel supply line, 100 of which are consumed in the engine, and the remaining 30 can be recovered upstream of the engine.

To this end, the system of this embodiment is provided with a fuel recovery line (RL) that recovers and recirculates liquefied gas not consumed by the engine among the fuel oversupplied to the engine, and a catch that receives the liquefied gas recovered from the engine in the fuel recovery line. A tank 200 is provided.

The liquefied gas recovered through the fuel recovery line (RL) is supplied to the front of the booster pump 110 of the fuel supply line (SL) through the catch tank 200 and recirculated.

The pressure and temperature of ammonia recovered from the engine through the fuel recovery line (RL) is around 25 barg and 55°C, and is supplied to the front of the booster pump of similar pressure through a catch tank, and is supplied from the fuel storage tank (T) to the supply pump ( It is supplied to the booster pump 110 together with the ammonia flow from the fuel supply line (SL) transferred through 100).

The catch tank 200 can also serve to store ammonia fuel remaining in the pipes during maintenance of pipes in the fuel supply system.

Since the ammonia temperature of the fuel supply line (SL) may vary depending on the ratio of ammonia recovered and supplied through the fuel recovery line and ammonia supplied from the fuel storage tank, the temperature controller 120 operates as a cooler or heater as needed. Controls the temperature of ammonia fuel supplied to the engine.

The heating medium in the heating medium circulation line (CL), in which the heating medium supplied to control the temperature of the liquefied gas circulates, is supplied to the temperature controller 120 as a heat source for cooling or heating the ammonia fuel. The heat medium may be glycol water, for example.

The heat medium circulation line (CL) is provided with a heat medium pump 300 that circulates the heat medium, and a heat medium heat exchanger 310 that adjusts the temperature of the heat medium transferred through the heat medium pump by heat exchange with seawater or fresh water and supplies it to the temperature controller. .

The heat medium exchanged between seawater or fresh water and the heat medium heat exchanger is supplied to the temperature controller 120 at around 36°C to cool or heat the ammonia so that it can be supplied to the engine at a constant temperature.

If the fuel supply line and fuel return line pass through the safety area of the engine room, a double pipe can be installed in the engine room safety area to prevent the risk of ammonia leaking from the pipe.

A gas valve unit (GVU) including valves for controlling ammonia supply is provided between the fuel supply line (SL) and fuel recovery line (RL) and the engine (E), and the fuel supply line and fuel recovery line each contain ammonia. To control the supply, a double block and bleed valve is installed to supply ammonia to the engine. When the ammonia fuel supply is interrupted due to the engine's fuel oil change, ammonia fuel mode stop, trip, etc., the temperature rises. When ammonia is gasified rather than liquid, each pipe can be double blocked, the pressure inside the pipe has been relieved, and purging can be performed with nitrogen (N ₂ ).

In addition, the first return line (RLa) is connected to the fuel recovery line (RL) downstream of the temperature controller 120, and the second return line (RLb) is connected to the fuel storage tank (T) at the rear end of the supply pump 100. do. Using the first and second return lines, the ammonia remaining in the fuel supply line can be discharged and recovered, such as when the ammonia fuel mode of the engine is stopped, or the pressure of the fuel supply line can be adjusted.

Meanwhile, in the system of this embodiment, the fuel storage tank (T) is provided as a pressure vessel such as a C-Type tank as described above, and ammonia can be stored at room temperature without installing a separate insulation material or insulation equipment. Depending on the ambient temperature, evaporation gas may be generated as ammonia stored in the fuel storage tank evaporates. In order to suppress the generation of evaporation gas and maintain a constant pressure in the fuel storage tank, the liquefied gas stored in the fuel storage tank is cooled before storing the fuel. A liquefied gas cooling line (ACL) is provided to return it to the tank.

The liquefied gas cooling line (ACL) is provided with a liquefied gas heat exchanger 320 that cools the liquefied gas through heat exchange. The liquefied gas heat exchanger can cool the liquefied gas through heat exchange by receiving heat medium that has passed through the heat medium heat exchanger 310. there is. For this purpose, part of the heat medium is branched from the rear end of the heat medium heat exchanger in the heat medium circulation line and supplied to the liquefied gas heat exchanger (CLa), and the heat medium that has passed through the liquefied gas heat exchanger is returned to the front end of the heat medium pump 300.

A vent line (VL) is connected from the fuel storage tank (T) to the vent mast (VM) provided on the upper part of the ship's main deck to discharge gas from the fuel storage tank, and the fuel storage tank is equipped with a safety valve (to prevent overpressure). STV) is prepared. Before the safety valve bursts, ammonia is sent from the fuel storage tank to the liquefied gas cooling line (ACL), cooled through the liquefied gas heat exchanger (320), and then returned to the fuel storage tank to lower the temperature of the fuel storage tank and prevent evaporation of ammonia. The pressure can be adjusted by discharging part of the ammonia gas in the fuel storage tank to the vent mast (VM) through the vent line (VL).

A gas discharge line (EL) is connected from the catch tank 200 to the vent mast, so that gas can be discharged from the catch tank to the vent mast.

Since ammonia is harmful to the human body and is corrosive, a vent mast can be installed on the weather deck or other open space above the main deck to ensure safety when discharging the gas.

It is clear 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 is self-evident.

E: engine
T: Fuel storage tank
LL: loading line
VR: Vapor Return Line
SL: Fuel supply line
RL: Fuel recovery line
CL: Heat medium circulation line
100: Supply pump
110: Booster pump
120: Temperature controller
200: Catch tank
300: heat medium pump
310: Heat medium heat exchanger
320: Liquefied gas heat exchanger

Claims (12)

A fuel storage tank provided on the ship and storing liquefied gas to be supplied as fuel for the ship's engines;
A fuel supply line connected from the fuel storage tank to the engine to supply liquefied gas;
A booster pump provided in the fuel supply line and compressing the liquefied gas to the fuel supply pressure of the engine;
A fuel recovery line that recovers and recirculates unconsumed liquefied gas among the liquefied gas supplied to the engine;
A catch tank provided in the fuel recovery line to accommodate liquefied gas recovered from the engine;
A supply pump provided in the fuel supply line and transporting liquefied gas from the fuel storage tank to the booster pump;
A temperature controller provided in the fuel supply line and receiving compressed liquefied gas from the booster pump to adjust the fuel supply temperature of the engine;
a first return line connected to the fuel recovery line downstream of the temperature controller; and
It includes a second return line connected to the fuel storage tank at the rear end of the supply pump,
The liquefied gas is compressed in a booster pump and supplied to the engine in a high-pressure liquid state, and the liquefied gas recovered through the fuel recovery line is supplied to the front end of the booster pump of the fuel supply line through the catch tank. Ship's fuel supply system. delete According to clause 1,
A heating medium circulation line through which the heating medium supplied to the temperature controller to control the temperature of the liquefied gas circulates;
a heat medium pump provided in the heat medium circulation line to circulate the heat medium; and
A fuel supply system for a ship further comprising a heat medium heat exchanger provided in the heat medium circulation line and controlling the temperature of the heat medium transferred through the heat medium pump by heat exchange with seawater or fresh water and supplying the heat medium to the temperature controller. According to clause 3,
A liquefied gas cooling line that cools the liquefied gas stored in the fuel storage tank and then returns it to the fuel storage tank; and
A fuel supply system for a ship further comprising: a liquefied gas heat exchanger provided in the liquefied gas cooling line and receiving heat medium that has passed through the heat medium heat exchanger and exchanging heat with the liquefied gas. According to clause 1,
A vent line connected from the fuel storage tank to the ship's vent mast to discharge gas from the fuel storage tank;
A safety valve provided to prevent overpressure in the fuel storage tank; and
A gas discharge line connected from the catch tank to the vent mast and discharging gas from the catch tank to the vent mast. According to clause 5,
It further includes a gas valve unit including valves that control the supply of liquefied gas between the fuel supply line and fuel recovery line and the engine,
A ship's fuel supply system, characterized in that a double block and bleed valve for controlling the supply of liquefied gas is installed in the fuel supply line and the fuel recovery line in the gas valve unit, respectively. According to any one of claims 1, 3 to 6,
The liquefied gas is ammonia,
The fuel supply system of a ship, characterized in that the engine is supplied with ammonia alone or together with other marine fuels including LNG, LPG, HFO, MGO, and Diesel Oil. According to clause 7,
A ship's fuel supply system, wherein the fuel storage tank is a pressurized tank with a design pressure of 5 to 30 barg. From the fuel storage tank that stores the liquefied gas to be supplied as fuel for the onboard engine, the liquefied gas is compressed by the fuel supply pressure of the engine in the booster pump, and the liquefied gas compressed by the booster pump is adjusted to the fuel supply temperature of the engine by the temperature controller. Adjust and supply to the engine along the fuel supply line,
The liquefied gas is compressed in a booster pump and supplied to the engine in a high-pressure liquid state,
Among the liquefied gas supplied to the engine, unconsumed liquefied gas is recovered through a fuel recovery line and supplied to the front of the booster pump of the fuel supply line through a catch tank for recirculation,
A first return line is connected to the fuel recovery line downstream of the temperature controller, and a second return line is provided in the fuel supply line to the fuel storage tank at the rear end of the supply pump that transfers the liquefied gas from the fuel storage tank to the booster pump. A fuel supply method for a ship characterized by this connection. According to clause 9,
A fuel supply method for a ship, characterized in that the heat medium, which circulates along the heat medium circulation line and whose temperature is adjusted by heat exchange with seawater or fresh water, is supplied to the temperature controller to control the temperature of the liquefied gas. According to clause 10,
A fuel supply method for a ship, characterized in that the liquefied gas stored in the fuel storage tank receives heat medium from the heat medium circulation line, is cooled by heat exchange, and then returns to the fuel storage tank. According to any one of claims 9 to 11,
The liquefied gas is ammonia,
A fuel supply method for a ship, characterized in that the fuel storage tank is a pressurized tank with a design pressure of 5 to 30 barg.

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