KR20220105536A - Electric propulsion system and ship having the same - Google Patents

Abstract

According to the present invention, provided is an electric propulsion system including an electric propulsion unit for generating propulsion of a ship. The electric propulsion system comprises: a gas combustion unit generating combustion gas by burning gas fuel in a liquefied gas storage tank mounted on the ship; a turbine operating using the combustion gas as a driving fluid; a generator connected to the turbine to produce electricity to supply to the electric propulsion unit; a heat exchanger for cooling the driving fluid discharged from the turbine with a heat medium; and a compressor for pressurizing the driving fluid discharged from the heat exchanger and supplying it to the gas combustion unit.

Description

Electric propulsion system and ship including the same

The present invention relates to an electric propulsion system and a ship including the same.

In general, ships use diesel engines to generate driving power using diesel oil, gas engines to generate driving power using gas such as LNG, and dual fuel engines to generate driving power by mixing diesel oil and gas. is promoted using

Recently, as the demand for eco-friendly/high-efficiency engines increases due to the strengthening of IMO environmental regulations, research on propulsion systems using various fuels is being actively conducted. In particular, technologies that can be promoted while reducing the emission of environmental pollutants such as carbon dioxide, sulfur oxides (SOx) and nitrogen oxides (NOx) emitted from ships are being studied.

Ships according to the prior art have installed environmental pollutant reduction devices such as scrubbers and SCRs in order to reduce the emission of environmental pollutants such as sulfur oxides (SOx) and nitrogen oxides (NOx).

However, there is a problem in that ships according to the prior art cannot satisfy the environmental regulations only with the environmental pollutant reduction device as the environmental regulations are gradually strengthened. As environmental regulations are strengthened, the processing capacity of the environmental pollutant reduction device should be increased, because the processing capacity is proportional to the size of the reduction device.

In a ship with limited space, if the proportion of environmental pollutant reduction devices increases, it is inefficient because not only the space for loading cargo or people is relatively reduced, but also fuel economy increases due to the weight of the reduction device. Therefore, there is an urgent need to develop a ship that is environmentally friendly and can be propelled with high efficiency.

The present invention was created to solve the problems of the prior art as described above, and an object of the present invention is to provide an electric propulsion unit for generating propulsion of a ship using electricity and an electric propulsion system including the same, thereby reducing environmental pollutants. It is to provide a ship that can reduce emissions. In particular, it is to provide an electric propulsion system capable of reducing the emission of carbon dioxide generated according to the combustion of gas fuel in a ship and a ship including the same.

In addition, it is an object of the present invention to provide an electric propulsion system capable of maximizing the use of space in a ship while providing the necessary propulsion force to the ship and a ship including the same.

An electric propulsion system according to an aspect of the present invention includes an electric propulsion unit for generating propulsion force of a ship, and a gas combustion unit for generating combustion gas by burning gas fuel in a liquefied gas storage tank mounted on the ship, the A turbine operating using combustion gas as a driving fluid, a generator connected to the turbine to produce electricity for supplying the electric propulsion unit, a heat exchanger for cooling the driving fluid discharged from the turbine to a heat medium, and the heat exchanger It may include a compressor that pressurizes the driving fluid discharged from and supplies it to the gas combustion unit.

Specifically, the electric propulsion system further includes a driving fluid circulation line connected to the gas combustion unit to circulate a driving fluid, and the turbine, the heat exchanger and the compressor are provided in the driving fluid circulation line. can

Specifically, the electric propulsion system further includes a carbon dioxide supply line for supplying at least a portion of a driving fluid flowing through the driving fluid circulation line to a carbon dioxide storage tank, wherein the carbon dioxide supply line is, in the driving fluid circulation line, It may be branching downstream of the heat exchanger.

Specifically, the heat exchanger, fuel gas supplied from the liquefied gas storage tank, fresh water and seawater supplied from the ship may cool the driving fluid as a heat medium.

Specifically, the electric propulsion system supplies a liquefied gas supply line for supplying the liquefied gas stored in the liquefied gas storage tank to the gas combustion unit, and the boil-off gas generated in the liquefied gas storage tank to the gas combustion unit. and a boil-off gas supply line, wherein the heat exchanger may be provided in the liquefied gas supply line.

An electric propulsion system according to another aspect of the present invention includes an electric propulsion unit and a main engine for generating propulsion of a ship, and includes a second heat exchanger that heats a driving fluid with waste heat generated in the main engine, the second heat exchanger 2 a turbine operating with a driving fluid heated in a heat exchanger, a generator connected to the turbine to generate electricity for supplying the electric propulsion unit, a heat exchanger for cooling the driving fluid discharged from the turbine into a heat medium, and the heat exchange It may include a compressor that pressurizes the driving fluid discharged from the unit and supplies it to the second heat exchanger.

Specifically, the electric propulsion system further includes a driving fluid circulation line connected to the second heat exchanger through which a driving fluid circulates, and the turbine, the heat exchanger, and the compressor are provided in the driving fluid circulation line. can

Specifically, the electric propulsion system further includes a liquefied gas storage tank for supplying gas fuel to the main engine, and the heat exchanger includes fuel gas supplied from the liquefied gas storage tank, fresh water and seawater supplied from the ship. At least one of them may be used as a heat medium to cool the driving fluid.

Specifically, the electric propulsion system may further include a waste heat recovery line for supplying waste heat generated from the main engine to the second heat exchanger, wherein the waste heat recovery line is an exhaust gas of the main engine or the waste heat recovery line Steam generated by using the exhaust gas in the economizer provided on the top may be supplied to the second heat exchanger.

The electric propulsion system and the ship including the same according to the present invention use liquefied gas stored as cargo or fuel in the ship as a gas fuel, and generate electricity by using the combustion gas generated according to the combustion of the gas fuel as a driving fluid. can be used for promotion. Accordingly, it is possible to reduce or not discharge the outboard emission of environmental pollutants contained in the combustion gas.

In addition, the electric propulsion system according to the present invention and a ship including the same can supply waste heat generated from the main engine of the ship to a driving fluid, and use the driving fluid to generate electricity and use it for electric propulsion.

In addition, as the electric propulsion system according to the present invention produces electricity using a driving fluid in a supercritical state, it is possible to provide significantly superior space utilization in the ship compared to a system for generating electricity using a conventional steam turbine.

1 is a conceptual diagram illustrating an electric propulsion system according to an embodiment of the present invention.
2 is a conceptual diagram illustrating an electric propulsion system according to another embodiment of the present invention.

The objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments taken in conjunction with the accompanying drawings. In the present specification, in adding reference numbers to the components of each drawing, it should be noted that only the same components are given the same number as possible even though they are indicated on different drawings. In addition, in describing the present invention, if it is determined that a detailed description of a related known technology may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

Hereinafter, it should be noted that high pressure, low pressure, high temperature, low temperature, and flow rate are relative and do not represent absolute values.

Hereinafter, liquefied gas may be used to encompass all substances that are vaporized in a gaseous state at room temperature, such as LNG or LPG, ethylene, ethane, ammonia, etc., but hereinafter, for convenience, it is assumed that the liquefied gas is LNG. In addition, the liquefied gas means a gas liquefied for storage, and the boil-off gas means a gas naturally vaporized, and the state of the liquefied gas or the boil-off gas is not limited to liquid and gas, respectively.

Hereinafter, a ship means a liquefied gas carrier for transporting liquefied gas, or a general merchant ship carrying cargo other than liquefied gas while loading liquefied gas as a propelling fuel. Furthermore, in this specification, the term "ship" may be interpreted as encompassing all offshore structures that require propulsion in addition to liquefied gas carriers and general merchant ships.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings.

1, an electric propulsion system according to an embodiment of the present invention will be described.

The electric propulsion system 1 according to this embodiment is a liquefied gas storage tank 100 , a gas combustion unit 120 , a turbine 121 , a generator 122 , a heat exchanger 123 , a compressor 124 , and carbon dioxide. It includes a storage tank 125 , an oxygen generator 130 , a switchboard 140 , a power storage device 150 , and an electric propulsion unit 160 .

The liquefied gas storage tank 100 stores liquefied gas. When the liquefied gas is LNG, the liquefied gas storage tank 100 may store the liquefied gas at a temperature of -160 degrees or less, and may have a thermal insulation structure so that the liquefied gas maintains a liquid phase.

The liquefied gas storage tank 100 is provided in an unrestricted type, and may be provided in, for example, a membrane type, an independent type, a pressurization type, and the like. In addition, it can be mounted on board a ship or mounted on a deck.

When the vessel is a liquefied gas carrier, the liquefied gas storage tank 100 may be a cargo tank, and when the vessel is a general commercial vessel other than a liquefied gas carrier, the liquefied gas storage tank 100 may be a separately installed fuel tank. For example, when the ship is a liquefied gas carrier, a plurality of liquefied gas storage tanks 100 may be arranged side by side in the ship.

At least a portion of the liquefied gas stored in the liquefied gas storage tank 100 is naturally evaporated due to external heat penetration, thereby generating boil-off gas in the liquefied gas storage tank 100 . Liquefied gas and boil-off gas may be different in composition, but both may be gas fuel consumed in the gas combustion unit 120 to be described later.

The liquid liquefied gas stored in the liquefied gas storage tank 100 may be withdrawn through the pump 101 and supplied to the consumer through the liquefied gas supply line L100. In this embodiment, the liquefied gas supply line L100 may supply the liquefied gas to the gas combustion unit 120 . A heat exchanger 123 is provided on the liquefied gas supply line L100 to cool the driving fluid supplied to the heat exchanger 123 by cooling heat of the liquefied gas. At least a portion of the liquefied gas passing through the heat exchanger 123 may be vaporized and supplied to the gas combustion unit 120 .

BOG generated inside the liquefied gas storage tank 100 may be withdrawn through the upper portion of the liquefied gas storage tank 100 and supplied to a demand through the BOG supply line L110. In this embodiment, the boil-off gas supply line L110 may supply the boil-off gas to the gas combustion unit 120 . The boil-off gas compressor 110 and the boil-off gas cooler 111 may be provided on the boil-off gas supply line L110. The flow rate of BOG generated in the liquefied gas storage tank 100 may vary depending on the environment in which the vessel is located, operating conditions, etc., and the BOG compressor 110 pressurizes BOG to the pressure required by the gas combustion unit 120 . can be supplied. The boil-off gas cooler 111 may supply the boil-off gas by cooling when the boil-off gas is heated to a temperature higher than the temperature required by the gas combustion unit 120 while being pressurized by the boil-off gas compressor 110 .

The gas combustion unit 120 may generate combustion gas by burning at least one of liquefied gas and boil-off gas supplied from the liquefied gas storage tank 100 as a gas fuel. Preferably, the gas combustion unit 120 may be to generate combustion gas by receiving and burning the liquefied gas forcibly vaporized while passing through the heat exchanger 123 through the liquefied gas supply line L100. The gas combustion unit 120 may receive oxygen produced by the oxygen generator 130 provided in the ship through the oxygen supply line L130 to burn gas fuel.

Although not shown, the gas combustion unit 120 may include a space for burning the gas fuel therein and a space for temporarily storing the combustion gas generated according to the combustion of the gas fuel. The combustion gas may include carbon dioxide and water vapor generated according to the combustion of the liquefied gas. The electric propulsion system 1 according to the present embodiment may use electricity produced by a combustion gas containing carbon dioxide as a driving fluid for propulsion of a ship.

A driving fluid circulation line L120 is connected to the gas combustion unit 120 so that combustion gas discharged from the gas combustion unit 120 may flow as a driving fluid along the driving fluid circulation line L120 . On the driving fluid circulation line L120, a turbine 121, a heat exchanger 123 and a compressor 124 may be provided based on the flow of the driving fluid discharged from the gas combustion unit 120, and the compressor 124. The driving fluid discharged from may be supplied to the gas combustion unit 120 again. Specifically, the driving fluid including carbon dioxide may constitute the Brayton cycle of carbon dioxide while flowing along the driving fluid circulation line L120 in a supercritical state.

The combustion gas generated while the gas fuel is burned in the gas combustion unit 120 may be heated in the gas combustion unit 120 to be isostatically expanded. The combustion gas discharged from the gas combustion unit 120 may be supplied to the turbine 121 through the driving fluid circulation line L120 .

The turbine 121 may generate rotational force by the pressure of the driving fluid supplied from the gas combustion unit 120 . The driving fluid supplied to the turbine 121 rotates the blades of the turbine 121 and may adiabatic expansion.

The generator 122 may be connected to the turbine 121 to generate electricity using rotational force generated by the driving fluid, and may supply the generated electricity to the electric propulsion unit 160 . For example, electricity produced by the generator 122 may be supplied to the electric propulsion unit 160 through the switchboard 140 provided in the ship. The switchboard 140 may be connected to an electricity demander in the ship to distribute and supply electricity produced by the generator 122 , and the power storage device (ESS, 150 ) may be connected to the switchboard 140 . The power storage device 150 stores the supplied electricity and, when necessary, supplies it back to the demanding place through the switchboard 140, etc., and may include a battery and the like. The electricity produced by the generator 122 may be supplied to the electric propulsion unit 160 through the switchboard 140 , and the surplus electricity may be stored in the power storage device 150 and then withdrawn and used when necessary. The electric propulsion unit 160 may receive electricity and operate the propeller to supply propulsion to the vessel.

In this embodiment, the size of the turbine 121 can be reduced to 1/10 of that of the conventional steam turbine by using a combustion gas containing carbon dioxide in a supercritical state, which has a significantly higher energy density than conventional steam, as the driving fluid. It is possible to maximize the space utilization of the ship. The driving fluid discharged from the turbine 121 may be supplied to the heat exchanger 123 through the driving fluid circulation line L120 .

The heat exchanger 123 cools the driving fluid discharged from the turbine 121 to uniformly compress the driving fluid. The heat exchanger 123 heats at least one of fuel gas supplied from the liquefied gas storage tank 100 , fresh water supplied from a ship, and seawater with a heat medium and a driving fluid to cool the driving fluid.

For example, the heat exchanger 123 is provided on the liquefied gas supply line L100 and the driving fluid circulation line L120, and the liquid liquefied gas supplied from the liquefied gas storage tank 100 cools the driving fluid as a heat medium. can do it In this case, at least a portion of the liquefied gas supplied with cooling heat through the heat exchanger 123 is vaporized to be combusted in the gas combustion unit 120 . When the ship is a liquefied gas propulsion ship using liquefied gas as fuel, the liquefied gas vaporized through the heat exchanger 123 may be supplied to and used not only by the gas combustion unit 120 but also by the fuel demanders such as the main engine (not shown). have.

For example, the heat exchanger 123 may be to cool the driving fluid using fresh water or seawater stored in the ship. In this case, the fresh water supplied with cooling heat through the heat exchanger 123 becomes steam and can be supplied and used to a steam demander in the ship, and the size of a boiler used for steam production in the ship can be reduced.

Although not shown, a plurality of heat exchangers 123 may be provided in parallel, and the driving fluid circulation line L120 may be provided to respectively supply driving fluid to the plurality of heat exchangers 123 . For example, the plurality of heat exchangers 123 may each use a different heat medium to cool the driving fluid, and the electric propulsion system 1 is the total flow rate of the driving fluid flowing through the driving fluid circulation line L120. Accordingly, it is possible to determine the required cooling heat to determine the flow rate of the driving fluid supplied to each heat exchanger 123 . The driving fluid discharged from the heat exchanger 123 may be supplied to the compressor 124 through the driving fluid circulation line L120 .

The compressor 124 is configured to pressurize the driving fluid discharged from the heat exchanger 123 and adiabically compress the driving fluid. The driving fluid may be heated in the process of being pressurized by the compressor 124 , and the driving fluid discharged from the compressor 124 is supplied back to the gas combustion unit 120 through the driving fluid circulation line L120 to the above-described circulation process. can be repeated.

In the electric propulsion system 1 according to this embodiment, when the flow rate of the driving fluid is greater than the flow rate for driving the turbine 121 or the electric propulsion system 1 is not operated, the driving fluid circulation line (L120) At least a portion of the driving fluid that circulates may be separately recovered and stored. The driving fluid is a combustion gas obtained by burning gas fuel supplied from the liquefied gas storage tank 100, and is mostly composed of carbon dioxide and water. Instead of discharging carbon dioxide to the outside of the electric propulsion system 1, the carbon dioxide storage tank 125. It will be possible to provide ships that comply with greenhouse gas emission regulations by temporarily storing them in the

Specifically, the electric propulsion system 1 may further include a carbon dioxide supply line L121 branching from the driving fluid circulation line L120. The carbon dioxide supply line L121 may branch at least a portion of the carbon dioxide flowing through the driving fluid circulation line L120 and supply it to the carbon dioxide storage tank 125 . The carbon dioxide storage tank 125 may be a pressure tank suitable for storing liquid carbon dioxide and carbon dioxide evaporated therefrom. The carbon dioxide supply line L121 may branch from the driving fluid circulation line L120 downstream of the heat exchanger 123 to supply carbon dioxide to the carbon dioxide storage tank 125 . Carbon dioxide in the driving fluid may be cooled in the heat exchanger 123 , and at least a portion may be liquefied and stored in the carbon dioxide storage tank 125 . Carbon dioxide stored in the carbon dioxide storage tank 125 may be used as an inert gas in the ship or may not be discharged during operation because it can be unloaded after anchoring in a port.

As such, the electric propulsion system 1 according to the present embodiment can generate electricity from a driving fluid generated by burning gas fuel and use it for propulsion of a ship. Since the driving fluid contains carbon dioxide in a supercritical state and has a high energy density, the turbine 121 can use a significantly reduced size compared to a conventional steam turbine, thereby maximizing the space utilization in the ship.

For example, as the size of the electric propulsion system 1 is reduced, the space of the ship's engine room may also be reduced, and as the electric propulsion system 1 completely replaces other propulsion means such as the main engine, the engine casing, the stack and It can provide a new vessel that can completely eliminate the same configuration.

In addition, carbon dioxide used in this process may be recycled through the driving fluid circulation line (L120) or stored in the carbon dioxide storage tank 125 so that it may not be discharged to the outside of the electric propulsion system (1). Ships can be provided, and the captured carbon dioxide can be provided for other uses in ships or ports.

2 is a conceptual diagram of an electric propulsion system according to another embodiment of the present invention.

Referring to FIG. 2 , the electric propulsion system 2 according to another embodiment of the present invention includes a liquefied gas storage tank 200 , a second heat exchanger 220 , a turbine 221 , a generator 222 , and heat exchange. It includes a machine 223 , a compressor 224 , a main engine 230 , and an electric propulsion unit 260 . Hereinafter, the same configuration as described above will be replaced with the description of the previous embodiment.

The electric propulsion system 2 according to the present embodiment includes both the main engine 230 and the electric propulsion unit 260, and is capable of producing the propulsion force of the ship by any one or more of them.

The main engine 230 generates propulsion by receiving the liquefied gas stored in the liquefied gas storage tank 200 as fuel, and may be an ME-GI engine, an X-DF engine, or the like, but is not limited thereto. The liquefied gas supply line L200 may take out the liquid liquefied gas stored in the liquefied gas storage tank 200 and supply it to the main engine 230, and to supply it at the temperature and pressure conditions required by the main engine 230. A pump 202 and a heater 203 may be provided. The BOG supply line L210 includes a BOG compressor 210 for supplying BOG by pressurizing and a BOG cooler 211 for adjusting BOG heated in the pressurization process to a temperature required by the main engine 230. can be provided In FIG. 2 , the liquefied gas supply line L200 and the boil-off gas supply line L210 are joined to be connected to the main engine 230 . However, depending on the type of the main engine 230 , any one or more is supplied as fuel. may be obtained, but is not limited thereto.

The electric propulsion system 2 according to this embodiment can heat the driving fluid flowing along the driving fluid circulation line L220 by using the waste heat generated by burning the liquefied gas in the main engine 230 . have. The driving fluid may be carbon dioxide or a mixture of fluids containing carbon dioxide, and may be circulated in a supercritical state in the driving fluid circulation line L220. For example, carbon dioxide in the exhaust gas discharged from the first main engine 230 may be supplied to the driving fluid circulation line L220 and used as the driving fluid, but is not limited thereto. A second heat exchanger 220 , a turbine 221 , a heat exchanger 223 , and a compressor 224 may be provided on the driving fluid circulation line L220 based on the flow of the driving fluid, and are discharged from the compressor 224 . The driving fluid used may be supplied to the second heat exchanger 220 again.

The second heat exchanger 220 may heat the driving fluid by exchanging the waste heat generated by the main engine 230 with the driving fluid of the driving fluid circulation line L220 . The main engine 230 and the second heat exchanger 220 may be connected through a waste heat recovery line L230. The waste heat recovery line L230 may directly supply the high-temperature exhaust gas discharged from the main engine 230 to the heat medium of the second heat exchanger 220 or supply a separate heat medium heated by the exhaust gas.

For example, the economizer 231 may be provided on the waste heat recovery line L230. The economizer 231 may generate steam by heating fresh water or seawater using the exhaust gas of the main engine 230, and the generated steam is supplied to the second heat exchanger 220 through the waste heat recovery line L230. It may be to heat the driving fluid.

In the second heat exchanger 220, the driving fluid containing carbon dioxide is heated by the heat medium to expand isostatically, and the driving fluid discharged from the second heat exchanger 220 is supplied to the turbine 221 to adiabically expand while rotating. can cause The generator 222 may be connected to the turbine 221 to produce electricity, and may supply the generated electricity to the electric propulsion unit 260 . The switchboard 240 may be connected to an electricity demander in the ship to distribute and supply electricity produced by the generator 222 .

The switchboard 240 may be connected to the electric propulsion unit 260 and the power storage device 250 , and may further be connected to a shaft generator (not shown) provided in the main engine 230 . In the case where the temperature of the exhaust gas is not high enough according to the output of the main engine 230 , and the driving fluid cannot be sufficiently heated in the second heat exchanger 220 , the turbine 221 is driven in the generator 222 . Electricity production may be insufficient. In this case, the electricity produced by the shaft generator connected to the main engine 230 is supplied to the electric propulsion unit 260 to secure the driving force.

As in the above-described embodiment, as the turbine 121 is rotated while circulating the supercritical carbon dioxide as the driving fluid, the turbine 121 having a size reduced to 1/10 of that of a conventional steam turbine can be used, so that the space utilization can be maximized.

The heat exchanger 223 may cool the driving fluid discharged from the turbine 221 to uniformly compress the driving fluid. The heat exchanger 223 heats at least one of fuel gas supplied from the liquefied gas storage tank 200 , fresh water supplied from a ship, and seawater with a heat medium and a driving fluid to cool the driving fluid.

For example, the heat exchanger 223 may be provided on the liquefied gas supply line L200 to cool the driving fluid with the liquid liquefied gas as a heat medium. At least a part of the liquefied gas used for cooling the driving fluid may be vaporized and supplied to the main engine 230 , and may be completely vaporized while passing through the pump 202 and the heater 203 and supplied to the main engine 230 . .

The compressor 224 may pressurize the driving fluid discharged from the heat exchanger 223 to thermally compress the driving fluid. The driving fluid discharged from the compressor 224 may be supplied back to the second heat exchanger 220 through the driving fluid circulation line L220 to repeat the above-described circulation process.

The electric propulsion system 2 according to this embodiment includes both the main engine 230 and the electric propulsion unit 260 , but using waste heat generated from the main engine 230 in the electric propulsion unit 260 . It is possible to improve the energy efficiency of the ship by generating electricity for it.

For example, when starting a ship, the main engine 230 is driven to secure propulsion, and by using carbon dioxide in the exhaust gas discharged from the main engine 230 as a driving fluid to produce electricity, after the initial driving, It is possible to secure propulsion by using both the main engine 230 and the electric propulsion unit 260 or to secure propulsion by using only the electric propulsion unit 260 . At this time, if the waste heat generated by the main engine 230 is not sufficient, the electricity produced by the turbine 221 and the generator 222 and the electricity produced by the shaft generator of the main engine 230 are used together for electric propulsion. can

Alternatively, when carbon dioxide is secured as the driving fluid, electricity can be directly produced by using the waste heat of the main engine 230, and as carbon dioxide in a supercritical state is used as the driving fluid, the turbine 221 has a larger size compared to the conventional steam turbine. It is possible to use the significantly reduced ones, so it is possible to maximize the utilization of the space in the ship.

It goes without saying that the present invention is not limited to the above-described embodiments, and a combination of the embodiments or a combination of at least one of the embodiments and a known technology may be included as another embodiment.

In the above, the present invention has been described focusing on the embodiments of the present invention, but this is only an example and does not limit the present invention. It will be appreciated that various combinations or modifications and applications not illustrated in the embodiments are possible within the scope. Accordingly, descriptions related to variations and applications that can be easily derived from the embodiments of the present invention should be interpreted as being included in the present invention.

1, 2: Electric propulsion system
100, 200: liquefied gas storage tank 101, 201: pump
110, 210: boil-off gas compressor 111, 211: boil-off gas cooler
120: gas combustion unit 121, 221: turbine
122, 222: generator 123, 223: heat exchanger
124, 224: compressor 125: carbon dioxide storage tank
130: oxygen generator 140, 240: switchboard
150, 250: power storage device 160, 260: electric propulsion unit
202: pump 203: heater
220: second heat exchanger 230: main engine
231: economizer
L100, L200: liquefied gas supply line L110, L210: boil-off gas supply line
L120, L220: Driving fluid circulation line L121: Carbon dioxide supply line
L130: oxygen supply line L230: waste heat recovery line

Claims (9)

An electric propulsion system comprising an electric propulsion unit for generating propulsion of a ship, the electric propulsion system comprising:
a gas combustion unit for generating combustion gas by burning gas fuel in a liquefied gas storage tank mounted on the ship;
a turbine operating using the combustion gas as a driving fluid;
a generator connected to the turbine to generate electricity for supplying the electric propulsion unit;
a heat exchanger for cooling the driving fluid discharged from the turbine as a heat medium; and
and a compressor that pressurizes the driving fluid discharged from the heat exchanger and supplies it to the gas combustion unit. The method of claim 1,
Further comprising a driving fluid circulation line connected to the gas combustion unit to circulate the driving fluid,
The turbine, the heat exchanger and the compressor are provided in the driving fluid circulation line, the electric propulsion system. 3. The method of claim 2,
Further comprising a carbon dioxide supply line for supplying at least a portion of the driving fluid flowing through the driving fluid circulation line to the carbon dioxide storage tank,
The carbon dioxide supply line is
in the driving fluid circulation line, branching downstream of the heat exchanger. The method of claim 1,
the heat exchanger,
Fuel gas supplied from the liquefied gas storage tank, at least one of fresh water and seawater supplied from the ship to cool the driving fluid as a heat medium, the electric propulsion system. The method of claim 1,
a liquefied gas supply line for supplying the liquefied gas stored in the liquefied gas storage tank to the gas combustion unit; and
Further comprising a boil-off gas supply line for supplying boil-off gas generated inside the liquefied gas storage tank to the gas combustion unit,
the heat exchanger,
Which will be provided in the liquefied gas supply line, electric propulsion system. An electric propulsion system comprising an electric propulsion unit and a main engine for generating propulsion of a ship, the electric propulsion system comprising:
a second heat exchanger for heating the driving fluid with waste heat generated from the main engine;
a turbine operating with the driving fluid heated in the second heat exchanger;
a generator connected to the turbine to generate electricity for supplying the electric propulsion unit;
a heat exchanger for cooling the driving fluid discharged from the turbine as a heat medium; and
and a compressor that pressurizes the driving fluid discharged from the heat exchanger and supplies it to the second heat exchanger. 7. The method of claim 6,
It further includes a driving fluid circulation line connected to the second heat exchanger through which the driving fluid circulates,
The turbine, the heat exchanger and the compressor are provided in the driving fluid circulation line, the electric propulsion system. 7. The method of claim 6,
Further comprising a liquefied gas storage tank for supplying gas fuel to the main engine,
the heat exchanger,
Fuel gas supplied from the liquefied gas storage tank, at least one of fresh water and seawater supplied from the ship to cool the driving fluid as a heat medium, the electric propulsion system. 7. The method of claim 6,
a waste heat recovery line for supplying waste heat generated from the main engine to the second heat exchanger;
The waste heat recovery line,
The exhaust gas of the main engine or steam generated by using the exhaust gas from an economizer provided on the waste heat recovery line is supplied to the second heat exchanger.

Images