KR20230136868A - LH2 Carrier - Google Patents

Abstract

A liquefied hydrogen carrier is launched. The liquefied hydrogen carrier of the present invention includes a hydrogen storage tank for storing liquefied hydrogen to be transported as cargo on a ship; A propulsion engine that generates propulsion to drive the propulsion propeller of the ship; An ammonia fuel tank storing ammonia to be supplied as fuel for the propulsion engine; An ammonia reformer (Cracker) that generates hydrogen by receiving ammonia boil-off gas generated from the ammonia fuel tank; and a gas turbine unit that produces the power required within the ship, wherein the hydrogen boil-off gas generated in the hydrogen storage tank and the hydrogen generated in the ammonia reforming unit are supplied to the gas turbine unit, and the hydrogen generated in the hydrogen storage tank is supplied to the gas turbine unit. The pressure of the hydrogen storage tank is controlled by supplying hydrogen boil-off gas to the gas turbine unit.

Description

Liquefied hydrogen carrier {LH2 Carrier}

The present invention relates to a liquefied hydrogen carrier, and more specifically, to a liquefied hydrogen carrier that stores and transports liquefied hydrogen and is propelled using eco-friendly fuel.

The existing economic system is based on carbon and is highly dependent on fossil fuels as an energy source, but fossil fuel reserves are limited and are expected to be depleted in the near future, and carbon dioxide (CO ₂ ) generated during combustion is a representative greenhouse gas. It is pointed out as the main cause of global warming and climate change and is subject to international emissions regulations.

In particular, recently, an international consensus has been formed on the seriousness of global warming and climate change problems, and efforts are being made to reduce greenhouse gas emissions around the world. As the 1997 Kyoto Protocol, which included obligations for developed countries to reduce greenhouse gases, expires in 2020, the Paris Climate Change Agreement (Paris Climate Change) was adopted at the 21st United Nations Framework Convention on Climate Change held in Paris, France in December 2015 and came into effect in November 2016. The 195 parties that participated in the agreement (Change Accord) are making various efforts aimed at reducing greenhouse gases.

Along with this global trend, interest in new energy such as renewable energy (or renewable energy) such as wind power, solar energy, solar heat, bioenergy, tidal power, and geothermal heat, and new energy such as hydrogen as a pollution-free energy that can replace fossil fuels is increasing, and various technologies are growing. Development is taking place.

Among them, hydrogen energy is environmentally friendly and has high energy density, so it can be used as a fuel for automobile power sources and fuel cells for portable electronic devices. The price of fuel cells that use hydrogen as fuel is decreasing every year, making it an ideal energy source for the future. As the era of hydrogen energy is receiving attention, the era of hydrogen energy is advancing, and demand for hydrogen is also increasing every year.

Meanwhile, as each country's interest in greenhouse gas and air pollutant emissions increases and international environmental regulation standards are rapidly strengthened, research on the development of eco-friendly marine fuel technology and eco-friendly energy transportation technology is also being actively conducted on ships.

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 research is being conducted on eco-friendly marine fuel that can reduce carbon dioxide emissions, and further on marine fuel for complete decarbonization. In particular, technologies for ships that can use ammonia, hydrogen, etc. as fuel are being actively researched and developed. there is.

Hydrogen is a non-toxic, colorless, and odorless gas and is the most abundant element in the universe. However, on Earth, hydrogen rarely exists alone. It exists in the form of compounds such as water and natural gas, so it must be separated from these substances. In order to use hydrogen energy widely and efficiently, economical and simple hydrogen production technology and transportation technology to transport it are first needed.

The present invention seeks to propose a technology related to a liquefied hydrogen carrier that can liquefy hydrogen, which is attracting attention as a future energy source, and transport it efficiently through ships.

According to one aspect of the present invention for solving the above-described problem, a hydrogen storage tank for storing liquefied hydrogen to be transported as cargo on a ship;

A propulsion engine that generates propulsion to drive the propulsion propeller of the ship;

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

An ammonia reformer (Cracker) that generates hydrogen by receiving ammonia boil-off gas generated from the ammonia fuel tank; and

Includes a gas turbine unit that produces the power needed onboard the ship,

Hydrogen boil-off gas generated in the hydrogen storage tank and hydrogen generated in the ammonia reforming unit are supplied to the gas turbine unit, and hydrogen boil-off gas generated in the hydrogen storage tank is supplied to the gas turbine unit to maintain the pressure of the hydrogen storage tank. A liquefied hydrogen carrier is provided, characterized in that controlling .

Preferably a gas supply line connected from the hydrogen storage tank to the gas turbine unit; and a gas supply unit provided in the gas supply line to receive hydrogen boil-off gas generated from the hydrogen storage tank and supply it to the gas turbine unit in accordance with the fuel supply conditions of the gas turbine unit.

Preferably, the ship is provided with a plurality of hydrogen storage tanks, and the pressure of the hydrogen storage tank is adjusted while first supplying hydrogen boil-off gas generated from the plurality of hydrogen storage tanks as fuel to the gas turbine unit, and the gas turbine unit is provided with a plurality of hydrogen storage tanks. Hydrogen can be supplied supplementally by generating hydrogen from the ammonia reforming unit to compensate for the shortage of hydrogen gas required in the unit.

Preferably, it may further include a BOG processing unit that receives and processes ammonia boil-off gas generated from the ammonia fuel tank.

Preferably, it further includes a fuel supply unit that supplies fuel from the ammonia fuel tank to the propulsion engine, wherein liquid ammonia is supplied to the propulsion engine as fuel through the fuel supply unit, and the propulsion engine Among the ammonia supplied, fuel that is not consumed in the engine may be recovered to the fuel supply unit, and ammonia in a liquid state may be re-supplied to the propulsion engine, and ammonia in a gaseous state may be supplied to the BOG processing unit.

Preferably, the fuel supply unit includes an ammonia supply line connected from the ammonia fuel tank to the propulsion engine; a fuel supply pump that transfers ammonia from the ammonia fuel tank to the ammonia supply line; A compression pump provided in the ammonia supply line and pressurizing ammonia according to the fuel supply pressure of the propulsion engine; A temperature controller provided in the ammonia supply line and controlling the temperature of ammonia according to the fuel supply temperature of the propulsion engine; and an ammonia recovery line that recovers fuel not consumed by the engine among the ammonia supplied to the propulsion engine. and a gas-liquid separator that receives fuel recovered from the ammonia recovery line, separates gas and liquid, and supplies ammonia in a liquid state to the ammonia supply line.

Preferably, the ammonia reforming unit receives ammonia boil-off gas generated from the ammonia fuel tank and gaseous ammonia separated from the gas-liquid separator and pyrolyzes it to generate hydrogen, and uses exhaust gas waste heat generated from the propulsion engine to generate hydrogen. This can be supplied as a heat source in the ammonia reforming unit.

Preferably, the gas turbine unit includes a hydrogen gas turbine that receives hydrogen boil-off gas generated in the hydrogen storage tank and hydrogen generated in the ammonia reforming unit and combusts it to generate high-temperature and high-pressure gas; And a generator that produces electricity by expanding the high-temperature and high-pressure gas generated in the hydrogen gas turbine.

It is possible to provide a liquefied hydrogen carrier that can liquefy hydrogen, which is attracting attention as a future energy source, and transport it efficiently through ships.

In particular, by using ammonia, an eco-friendly fuel with no greenhouse gas emissions, as fuel for propulsion engines, it is possible to reduce greenhouse gas emissions from ship operations and create an eco-friendly ship.

In addition, the hydrogen generated by reforming the hydrogen boil-off gas and ammonia boil-off gas generated from the hydrogen storage tank that stores the liquefied hydrogen to be transported as cargo is used as fuel to produce and supply the power required on board the ship, thereby reducing the hydrogen boil-off gas and ammonia generated during transportation. It can effectively treat ammonia boil-off gas and prevent pressure increases in hydrogen storage tanks to ensure ship safety.

Furthermore, energy efficiency on board is increased by utilizing the exhaust gas waste heat generated from the propulsion engine during ammonia reforming, and fuel costs are reduced by supplying power generation by supplying hydrogen generated by reforming ammonia as fuel instead of directly vaporizing and supplying hydrogen, which is expensive. At the same time, it can flexibly respond to the power requirements within the ship.

Figure 1 schematically shows a liquefied hydrogen carrier 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.

Figure 1 schematically shows a propulsion and power generation system in a liquefied hydrogen carrier according to an embodiment of the present invention.

As shown in Figure 1, this system includes a hydrogen storage tank (CT) that stores liquefied hydrogen to be transported as cargo on a ship, and a propulsion engine (E) that generates propulsion to drive the ship's propulsion propeller (PP). ), an ammonia fuel tank (FT) that stores fuel to be supplied to the propulsion engine, a fuel supply unit (100) that supplies fuel from the ammonia fuel tank to the propulsion engine, and a gas turbine unit that produces power necessary for the ship.

In this system, the propulsion engine may be supplied with ammonia alone, or may be dual fuel supplied with ammonia together with other fuels such as LPG or marine oil such as HFO, LSFO, MGO, MDO, ULSFO, etc. It could be the engine.

In the ammonia fuel tank, ammonia to be supplied to the propulsion engine is stored in a liquid state, for example, at around -34°C, and is supplied to the propulsion engine in liquid form through the fuel supply unit. Ammonia boil-off gas generated from liquid ammonia stored in the fuel tank can be supplied to the ammonia reformer (Cracker) 400 and processed to generate hydrogen through reforming.

The hydrogen generated in the ammonia reforming section is supplied to the gas turbine section along with the hydrogen boil-off gas generated in the hydrogen storage tank and used as fuel for power production within the ship.

First, looking at the fuel supply process to the propulsion engine (E), this system is provided with a fuel supply unit 100 that supplies liquid ammonia from the ammonia fuel tank to the propulsion engine.

An ammonia supply line (FSL) is provided from the ammonia fuel tank to the propulsion engine, and a fuel supply pump is provided in the ammonia fuel tank to transfer ammonia to the propulsion engine along the ammonia supply line.

The fuel supply unit 100 is provided in the ammonia supply line and includes a compression pump (not shown) that pressurizes ammonia according to the fuel supply pressure of the propulsion engine. It is provided in the ammonia supply line and supplies ammonia according to the fuel supply temperature of the propulsion engine. It may include a thermostat (not shown) that controls the temperature.

Liquid ammonia transferred from the ammonia fuel tank (FT) through the fuel supply pump is compressed and heated according to the fuel supply conditions of the propulsion engine through a temperature controller and compression pump and supplied to the propulsion engine (E) in a high-pressure liquid state. You can. The arrangement order of the temperature controller and compression pump can be changed.

Meanwhile, among the fuel supplied to the propulsion engine, the fuel that is not consumed by the engine can be discharged from the propulsion engine through the ammonia recovery line (FRL) and recovered to the fuel supply unit 100 upstream of the engine. The fuel is transferred to a gas-liquid separator (not shown) in the fuel supply section, and after gas-liquid separation, ammonia in liquid state is joined to the ammonia supply line (FSL) and can be re-supplied as propulsion engine fuel through a compression pump and temperature controller. In this system, ammonia is supplied as engine fuel in a high-pressure liquid state. Unlike when gas fuel is supplied, which is a compressible fluid whose volume changes greatly depending on pressure changes, it is an incompressible fluid whose volume changes little or no even when pressure is applied. In other words, when liquid fuel is supplied to the engine, sufficient fuel can be supplied to immediately respond to changes in engine load, and excess fuel can be supplied to the engine to prevent cavitation. Among the fuel excessively supplied to the propulsion engine, the fuel remaining after being consumed by the engine is discharged from the engine and recirculated through a gas-liquid separator (not shown). The gaseous ammonia separated in the gas-liquid separator may be supplied to the BOG treatment unit 300 for processing. In the BOG processing unit, ammonia gas can be supplied, compressed, and supplied to an ammonia reforming unit (cracker) or re-liquefied and returned to a fuel tank.

Meanwhile, the ship of this embodiment is a liquefied hydrogen carrier that transports liquefied hydrogen, an eco-friendly fuel, as the ship's cargo, and the ship is equipped with a hydrogen storage tank (CT) to store liquefied hydrogen.

Hydrogen has a very low boiling point of about -253°C, so it usually exists in a gaseous state. However, when liquefied, its volume is reduced to 1/800, so for storage and transportation efficiency, in the carrier of this embodiment, it is stored in a hydrogen storage tank in the form of liquefied hydrogen and transported. do. A ship may be equipped with a plurality of hydrogen storage tanks, and each hydrogen storage tank is equipped with a structure and material that can store cryogenic liquefied hydrogen.

Since hydrogen has a very low boiling point, hydrogen evaporation gas continues to be generated from liquefied hydrogen stored in a hydrogen storage tank. In this embodiment, a gas turbine unit including a hydrogen gas turbine (HT) and a generator (G) is provided to supply and treat hydrogen boil-off gas generated in a hydrogen storage tank as hydrogen gas turbine fuel, thereby producing power to be supplied to the ship. Configure it so that In this way, an eco-friendly ship is realized by providing a propulsion engine that uses carbon-free ammonia as fuel and generating electricity using carbon-free hydrogen as fuel to supply the necessary power on board, while reducing the hydrogen boil-off gas generated during transportation. can be treated effectively to prevent pressure increases in hydrogen storage tanks and ensure ship safety.

For this purpose, the gas turbine part of the ship in this embodiment includes a hydrogen gas turbine (HT) that receives hydrogen and combusts it to generate high-temperature and high-pressure gas, and a generator that produces electricity by expanding the high-temperature and high-pressure gas generated in the hydrogen gas turbine. (G) is prepared. Hydrogen gas turbines (HT) and generators (G) can be installed in multiple numbers to meet the total power demand within the ship, and the generated power is distributed to each power demand source through a switchboard, etc.

To supply fuel to the hydrogen gas turbine, a gas supply line (GL) is provided from the hydrogen storage tank to the gas turbine section, and the gas supply line receives hydrogen boil-off gas generated from the hydrogen storage tank to determine the fuel supply conditions of the gas turbine section. Accordingly, a gas supply unit 200 that supplies gas to the gas turbine unit is provided. The gas supply unit 200 may include a hydrogen compressor that compresses hydrogen boil-off gas according to the fuel supply conditions of the co-fired gas turbine, a heater that adjusts the temperature of hydrogen boil-off gas according to the turbine inlet temperature, and the like.

In addition, hydrogen has a very expensive fuel cost, but in this embodiment, an ammonia reforming unit 400 is provided in consideration of operating fuel costs, and the ammonia boil-off gas generated in the relatively inexpensive ammonia fuel tank (FT) is reformed to produce hydrogen. After being generated, it is configured to be supplied as hydrogen gas turbine fuel.

Accordingly, hydrogen produced from ammonia is supplied to the hydrogen gas turbine (HT) through the hydrogen boil-off gas generated in the hydrogen storage tank (CT) and the ammonia reforming unit 400.

When multiple hydrogen storage tanks are provided, the hydrogen boil-off gas generated from each hydrogen storage tank at the lowest flow rate required to control the tank pressure is sent to the hydrogen gas turbine to generate electricity while safely maintaining the pressure of each hydrogen storage tank. maintain If additional power production from the hydrogen gas turbine and generator is required depending on the power demand on board, the ammonia boil-off gas generated from the ammonia fuel tank is reformed to generate hydrogen and then supplied to the hydrogen gas turbine, thereby supplying the hydrogen fuel required for the entire power generation capacity. By minimizing the amount of hydrogen stored in the hydrogen storage tank, operational fuel costs can be reduced. Furthermore, the loading limit of the hydrogen storage tank can be maximized by maintaining the MARVS (Maximum Relief Valve Setting) of the hydrogen storage tank at a low value without requiring a separate processing device for hydrogen evaporation gas treatment.

Ammonia evaporation gas generated from the ammonia fuel tank is supplied directly to the ammonia reforming unit 400 through the reforming line (CL), or is compressed through the BOG treatment unit 300 through the evaporation gas discharge line (BL) to the ammonia reforming unit ( 400). Gaseous ammonia discharged from a fuel supply unit such as the above-described gas-liquid separator (not shown) may also be compressed through the BOG treatment unit 300 and then supplied to the ammonia reforming unit 400.

The ammonia reforming unit 400 includes a decomposition unit (not shown) that receives ammonia and thermally decomposes it to generate decomposed gas containing hydrogen, nitrogen, and undecomposed ammonia, and an undecomposed ammonia removal unit that removes undecomposed ammonia from the decomposed gas ( (not shown), and a hydrogen purifier (not shown) that receives decomposed gas that has passed through the undecomposed ammonia removal unit, removes nitrogen, and purifies it into hydrogen.

Ammonia gas is compressed in the BOG processing unit 300 and supplied to a decomposition unit, where it is thermally decomposed and separated into hydrogen and nitrogen. The decomposition gas contains some gaseous ammonia that has not been decomposed in the decomposition unit. The decomposer may be configured to include a combustion chamber for thermally decomposing ammonia.

At this time, high-temperature exhaust gas waste heat generated from the propulsion engine can be supplied as the heat source of the decomposer. By supplying the high-temperature exhaust discharged from the propulsion engine to a decomposer, recovering the waste heat, and discharging it overboard, the amount of energy required for ammonia reforming can be reduced and the energy efficiency of the ship can be increased. If the heat source of the decomposer due to exhaust gas is insufficient, additional heat energy can be supplied through a burner (not shown).

The decomposition gas containing hydrogen, nitrogen, and unresolved ammonia generated in the decomposition unit is supplied to the undecomposed ammonia removal unit, and the undecomposed ammonia contained in the decomposed gas is removed.

Ammonia has a very high water solubility of about 89.5, while hydrogen and nitrogen have very low water solubility of 0.0002 and 0.003, respectively. In the undecomposed ammonia removal section, it is decomposed by thermal swing adsorption (TSA). The gas is transferred to a water port, and the undecomposed ammonia contained in the decomposed gas is dissolved in water and collected, and the decomposed gas that has passed through the water port can be purified by sending it to a hydrogen purifier through the upper part of the water port.

In a hydrogen purifier, nitrogen in the decomposition gas is removed through pressure swing adsorption (PSA), and hydrogen can be purified and then supplied as hydrogen gas turbine fuel.

As discussed above, this embodiment adopts ammonia, an eco-friendly fuel, as the fuel for the propulsion engine while transporting liquefied hydrogen on a ship, and hydrogen generated by reforming the hydrogen boil-off gas and ammonia boil-off gas generated from the hydrogen storage tank. By producing and supplying the necessary power on board with fuel, we realize an eco-friendly ship with zero carbon emissions, effectively treat hydrogen evaporation gas generated during transportation, prevent pressure increases in hydrogen storage tanks, ensure ship safety, and ensure operating costs. can save.

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.

CT: Hydrogen storage tank
FT: Ammonia fuel tank
E: engine for propulsion
HT: Hydrogen gas turbine
100: Fuel supply unit
200: Gas supply unit
300: BOG processing unit
400: Ammonia reforming unit

Claims (8)

A hydrogen storage tank that stores liquefied hydrogen to be transported as cargo on a ship;
A propulsion engine that generates propulsion to drive the propulsion propeller of the ship;
An ammonia fuel tank storing ammonia to be supplied as fuel for the propulsion engine;
An ammonia reformer (Cracker) that generates hydrogen by receiving ammonia boil-off gas generated from the ammonia fuel tank; and
Includes a gas turbine unit that produces the power needed onboard the ship,
Hydrogen boil-off gas generated in the hydrogen storage tank and hydrogen generated in the ammonia reforming unit are supplied to the gas turbine unit,
A liquefied hydrogen carrier, characterized in that the pressure of the hydrogen storage tank is adjusted by supplying hydrogen boil-off gas generated in the hydrogen storage tank to the gas turbine unit. According to clause 1,
A gas supply line connected from the hydrogen storage tank to the gas turbine unit; and
A liquefied hydrogen carrier further comprising a gas supply unit provided in the gas supply line to receive hydrogen boil-off gas generated from the hydrogen storage tank and supply it to the gas turbine unit in accordance with the fuel supply conditions of the gas turbine unit. According to clause 2,
The ship is provided with a plurality of hydrogen storage tanks, and the hydrogen boil-off gas generated from the plurality of hydrogen storage tanks is first supplied as fuel to the gas turbine unit, thereby controlling the pressure of the hydrogen storage tank, and controlling the pressure of the hydrogen storage tank as required by the gas turbine unit. A liquefied hydrogen carrier characterized in that hydrogen is generated from the ammonia reforming unit to supplement the hydrogen gas shortage. According to clause 2,
A liquefied hydrogen carrier further comprising a BOG processing unit that receives and processes ammonia boil-off gas generated from the ammonia fuel tank. According to clause 4,
It further includes a fuel supply unit that supplies fuel from the ammonia fuel tank to the propulsion engine,
Liquid ammonia is supplied as fuel to the propulsion engine through the fuel supply unit,
Among the ammonia supplied to the propulsion engine, fuel not consumed by the engine is recovered to the fuel supply unit, liquid ammonia is re-supplied to the propulsion engine, and gaseous ammonia is supplied to the BOG processing unit. A liquid hydrogen carrier. The method of claim 5, wherein the fuel supply unit
An ammonia supply line connected from the ammonia fuel tank to the propulsion engine;
a fuel supply pump that transfers ammonia from the ammonia fuel tank to the ammonia supply line;
A compression pump provided in the ammonia supply line and pressurizing ammonia according to the fuel supply pressure of the propulsion engine;
A temperature controller provided in the ammonia supply line and controlling the temperature of ammonia according to the fuel supply temperature of the propulsion engine; and
An ammonia recovery line that recovers fuel not consumed by the engine among the ammonia supplied to the propulsion engine; and
A liquefied hydrogen carrier comprising a gas-liquid separator that receives fuel recovered from the ammonia recovery line, separates gas and liquid, and supplies liquid ammonia to the ammonia supply line. According to clause 6,
In the ammonia reforming unit, ammonia boil-off gas generated from the ammonia fuel tank and gaseous ammonia separated from the gas-liquid separator are supplied and thermally decomposed to produce hydrogen.
A liquefied hydrogen carrier, characterized in that exhaust gas waste heat generated from the propulsion engine is supplied as a heat source of the ammonia reforming unit. The method of any one of claims 1 to 7, wherein the gas turbine unit
A hydrogen gas turbine that receives hydrogen boil-off gas generated from the hydrogen storage tank and hydrogen generated from the ammonia reforming unit and combusts it to generate high-temperature and high-pressure gas; and
A liquefied hydrogen carrier further comprising a generator that produces electricity by expanding the high-temperature and high-pressure gas generated in the hydrogen gas turbine.

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