KR102201185B1 - Electric propulsion system and ship having the same - Google Patents

Abstract

The present invention relates to an electric propulsion system and a ship including the same, comprising: an electric propulsion system including a power generation engine and a fuel cell for generating electricity for propulsion of the ship by consuming gas fuel from a liquefied gas storage tank mounted on the ship As, the fuel cell, while consuming the liquefied gas from the liquefied gas storage tank, is operated with a constant base load, and the power generation engine is an auxiliary load in which the power generation amount is varied while consuming the boil-off gas generated from the liquefied gas storage tank. It is characterized by movable.

Description

Electric propulsion system and ship having the same}

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

In general, ships are diesel engines that generate driving power using diesel oil, gas engines that generate driving power using gases such as LNG, and dual fuel engines that generate driving power by mixing diesel oil and gas. Use to promote.

Recently, as the demand for eco-friendly/high-efficiency engines according to the reinforcement of IMO environmental regulations increases, research on propulsion systems using various fuels is actively underway. In particular, technologies that can be promoted while reducing the emission of environmental pollutants such as 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 to reduce emissions of environmental pollutants such as sulfur oxides (SOx) and nitrogen oxides (NOx).

However, ships according to the prior art have a problem in that environmental regulations cannot be satisfied only with environmental pollutant reduction devices as environmental regulations are increasingly strengthened. As environmental regulations are reinforced, the treatment capacity of the environmental pollutant reduction device must be increased, because the treatment capacity is proportional to the size of the reduction device.

In a ship with limited space, if the proportion of the environmental pollutant reduction device increases, it is inefficient because the space for loading cargo or the space for carrying people is relatively reduced, and 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 promoted 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 system capable of propulsion with high efficiency while being eco-friendly using a fuel cell, and a ship including the same.

An electric propulsion system according to an aspect of the present invention is an electric propulsion system having a power generation engine and a fuel cell for generating electricity for propulsion of the ship by consuming gas fuel from a liquefied gas storage tank mounted on a ship, the The fuel cell operates at a base load with a constant amount of power generation while consuming the liquefied gas in the liquefied gas storage tank, and the power generation engine operates with an auxiliary load in which the amount of power generation varies while consuming the boil-off gas generated in the liquefied gas storage tank. It is characterized.

Specifically, a desulfurizer may be omitted between the liquefied gas storage tank and the fuel cell.

Specifically, it may further include a reformer provided between the liquefied gas storage tank and the fuel cell to separate hydrogen from the liquefied gas.

Specifically, the boiler further includes a boiler having a burner that converts fresh water into steam by burning gas fuel, wherein the amount of steam generated may be varied while consuming boil-off gas.

Specifically, the fuel cell may have a relatively small amount of power generation than the power generation engine.

Specifically, the power generation engine may be composed of two or more power generation engines having different power generation amounts.

Specifically, the first power generation engine may have a power generation amount corresponding to the amount of electricity required when the ship is anchored, and the fuel cell and the power generation engine may have a total power generation amount corresponding to the amount of electricity required when the ship is operated.

Specifically, the first power generation engine may operate with a constant amount of power generation while consuming the boil-off gas generated in the liquefied gas storage tank when the ship is anchored.

A ship according to an aspect of the present invention is characterized by having the electric propulsion system.

The electric propulsion system and the ship including the same according to the present invention are capable of reducing emissions of environmental pollutants such as sulfur oxides (SOx) and nitrogen oxides (NOx), as well as energy efficiency and Fuel economy can be improved.

1 is a conceptual diagram of an electric propulsion system according to a first embodiment of the present invention.
2 is a conceptual diagram of an electric propulsion system according to a second embodiment of the present invention.
3 is a conceptual diagram of an electric propulsion system according to a third embodiment of the present invention.
4 is a conceptual diagram of an electric propulsion system according to a fourth embodiment of the present invention.
5 is a conceptual diagram of an electric propulsion system according to a fifth embodiment of the present invention.
6 is a conceptual diagram of an electric propulsion system according to a sixth embodiment of the present invention.
7 is a conceptual diagram of an electric propulsion system according to a seventh embodiment of the present invention.
8 is a conceptual diagram of an electric propulsion system according to an eighth embodiment of the present invention.

Objects, specific advantages and novel features of the present invention will become more apparent from the following detailed description and preferred embodiments associated with the accompanying drawings. In adding reference numerals to elements of each drawing in the present specification, it should be noted that, even though they are indicated on different drawings, only the same elements are to have the same number as possible. In addition, in describing the present invention, when it is determined that a detailed description of related known technologies may unnecessarily obscure the subject matter of the present invention, the detailed description thereof will be omitted.

Hereinafter, preferred embodiments of the present invention will be described in detail with reference to the accompanying drawings. For reference, in the present specification, the liquefied gas may be used in the sense of encompassing all substances vaporized in a gaseous state at room temperature, such as LNG or LPG, ethylene, ethane, ammonia, etc., but for convenience, the liquefied gas is assumed to be LNG. .

In addition, the liquefied gas refers to a gas that has been liquefied for storage and the evaporated gas refers to a gas that has been naturally vaporized, and the states of the liquefied gas or the evaporated gas are not limited to liquid and gas, respectively.

The present invention relates to a ship including an electric propulsion system and an electric propulsion system described below, wherein the ship is a liquefied gas carrier that transports liquefied gas, or a liquefied gas as propulsion fuel while loading cargo other than liquefied gas. It covers general merchant ships, etc. Furthermore, in the present specification, the term ship may be interpreted as encompassing all offshore structures that require propulsion other than a general commercial ship.

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

Referring to FIG. 1, the electric propulsion system 1 according to the first embodiment of the present invention is a system that consumes gas fuel to produce electricity for propulsion of a ship, and includes a liquefied gas storage tank 10 and a power generation engine. (20a, 20b), a fuel cell 30, an economizer 40, and a boiler 50a, 50b.

The liquefied gas storage tank 10 stores liquefied gas. When the liquefied gas is LNG, the liquefied gas storage tank 10 may store the liquefied gas at a temperature of -160 degrees or less, and may have an insulating structure so that the liquefied gas can maintain a liquid phase.

The liquefied gas storage tank 10 is provided in an unrestricted type, and for example, may be provided in a membrane type, a standalone type, a pressurized type, or the like. In addition, it can be mounted on board a ship or mounted on a deck.

When the ship is a liquefied gas carrier, the liquefied gas storage tank 10 may be a cargo tank, and when the ship is a general merchant ship other than a liquefied gas carrier, the liquefied gas storage tank 10 may be a separately installed fuel tank.

At least part of the liquefied gas stored in the liquefied gas storage tank 10 is vaporized due to external heat permeation, and thus, boil-off gas is generated in the liquefied gas storage tank 10. Although the liquefied gas and the boil-off gas differ in their components, they may all be gaseous fuel consumed by the power generation engines 20a and 20b and the fuel cell 30 to be described later.

In the liquefied gas storage tank 10, a liquefied gas supply line (L1)/evaporated gas supply line (L2) through which gas fuel is supplied may be provided as the power generation engines 20a, 20b and the fuel cell 30, and each line In the liquefied gas supply valve (V1) / evaporation gas supply valve (V2) is provided, the supply flow rate of the gas fuel can be adjusted.

The power generation engines 20a and 20b consume gas fuel to produce electricity. Power generation engines (20a, 20b) may be provided in at least one or more, for example, may be provided in two or more as shown in the drawing.

The plurality of power generation engines 20a and 20b may have different amounts of power generation. For example, the first power generation engine 20a may have a power generation amount of about 2 to 3MW, and the second power generation engine 20b may have a power generation amount of about 8MW.

Conventionally, when a plurality of power generation engines (20a, 20b) are provided, it was common to arrange a plurality of power generation engines (20a, 20b) having the same power generation amount (for example, to secure a total power generation amount of 10MW, a power generation engine of 5MW ( 20a, 20b) 2 units installed).

However, the amount of electricity required while the ship is at anchor (meaning the amount of electricity required for loading and unloading cargo, supplying electricity in the cabin, operating basic equipment, etc.) is the amount of electricity required for the operation of the ship (10MW) and the number of power generation engines (20a, 20b). Since it is smaller than that divided by (2 units) (2~3MW), in the conventional case, one power generation engine (20a, 20b) must be operated with a low load.

On the other hand, in the present invention, considering that the efficiency decreases when the power generation engines 20a and 20b are operated at a low load, the power generation amount of the first power generation engine 20a (which can add the power generation amount of the fuel cell 30) is a ship The second power generation engine 20b may be provided to have a power generation amount corresponding to the amount of electricity required at the time of anchoring, and having a power generation amount of at least twice that of the first power generation engine 20a.

In this case, the present invention presupposes 100% load operation of the power generation engines 20a and 20b, but the power generation amount of the first power generation engine 20a (about 2MW), the power generation amount of the second power generation engine 20b (about 8MW), In the order of the total power generation of the power generation engines 20a and 20b (around 10MW), it is possible to select three stages of power generation that are more than the number of power generation engines 20a and 20b.

In addition, when the ship is anchored, the first power generation engine 20a is operated at 100% and the second power generation engine 20b is not operated, so that the present invention decreases efficiency due to the low-load operation of the power generation engines 20a and 20b. Can be suppressed.

Of course, in the present invention, the power generation engines 20a, 20b (power generation engines 20a, 20b, several fuel cells 30) may have a total power generation amount corresponding to the amount of electricity required during operation of the ship, for example a second power generation engine The amount of power generation in (20b) may correspond to the amount of electricity required for the operation of the ship, minus the amount of electricity required for anchoring the ship.

Therefore, the present invention is a combination of the power generation engines (20a, 20b) of different power generation amount, unlike the prior art in which a plurality of power generation engines (20a, 20b) of the same specifications are arranged, both power generation engines (20a, 20b) during berth / operation High-load and high-efficiency operation can be guaranteed.

The power generation engines 20a and 20b generate electricity by consuming gaseous fuel such as liquefied gas or evaporation gas, and the power generation engines 20a and 20b generate high-temperature exhaust of about 400 degrees Celsius. Such high-temperature exhaust can be used to generate steam, which will be described later.

The fuel cell 30 consumes gas fuel to produce electricity for propulsion of a ship. The fuel cell 30 can have a relatively small amount of power generation than the power generation engines 20a and 20b (for example, around 1MW, which is 0.5 times less than the first power generation engine 20a), and is always operated with a base load, so that the minimum amount of power generation in the ship Can always maintain.

In the present invention, the fuel cell 30 may be an SOFC, and in the case of the SOFC, high-temperature exhaust of about 300 degrees Celsius is generated. At this time, the high-temperature exhaust may be used for steam production together with the exhaust of the power generation engines 20a and 20b mentioned above.

The fuel cell 30 generates electricity using pure hydrogen, and although the liquefied gas contains hydrogen, it contains methane (CH4) in which four hydrogen atoms are bonded to one carbon atom as a main component. It does not have a molecule as its main component.

Therefore, reforming is required in order to change the liquefied gas in which carbon is bonded to hydrogen into a state that can be used in the fuel cell 30 (hydrogen atom/hydrogen molecule from which carbon is separated), and for this purpose, liquefied gas is stored. A reformer 31 for separating hydrogen from the liquefied gas may be provided between the tank 10 and the fuel cell 30. However, since the specific configuration of the reformer 31 is the same as in the prior art, a detailed description will be omitted.

When the electricity generated by the power generation engines 20a and 20b and the fuel cell 30 exceeds the amount of electricity required by the ship, the excess electricity is stored in an energy storage system (ESS, not shown) or a load bank , Not shown).

When the present invention is equipped with an energy storage system, the excess electricity stored in the energy storage system is used instead of when electricity that can be generated by the low-load operation of the power generation engines 20a and 20b is used, and the power generation engines 20a and 20b ) Efficiency can be guaranteed.

However, the present invention is applied to a ship sailing the sea, and if excess electricity is generated during sailing, it can be consumed by increasing the speed of the ship, and storage is required as only a part of the power generation engines 20a and 20b are operated at anchoring. Since excess electricity is not generated, an energy storage system may not be provided.

The economizer 40 heats fresh water using exhaust gas discharged from the fuel cell 30. However, in the present specification, the term “fresh water” may be interpreted as a term encompassing all substances (seawater, etc.) that can be converted into steam in addition to fresh water without impurities as a substance that becomes steam when vaporized.

The economizer 40 heats fresh water with hot water. That is, at least most of the fresh water heated by the economizer 40 may remain liquid without phase change. This is because, as the fuel cell 30 has a power generation amount smaller than that of the power generation engines 20a and 20b, the flow rate of exhaust flowing from the fuel cell 30 to the economizer 40 is not sufficient.

Of course, in the present invention, the high-temperature water discharged from the economizer 40 refers to fresh water that has not been converted into steam, but is not limited to a state in which no steam is included.

A fresh water inlet line L20 is connected to the economizer 40, and the flow rate of fresh water flowing into the economizer 40 can be controlled by a fresh water pump 41, a fresh water inlet valve V20, etc., and the fresh water inlet line L20 ) May be connected to the boilers 50a and 50b to be described later via the economizer 40.

At this time, the fresh water flowing along the fresh water inlet line L20 may be changed into hot water by the economizer 40 and then phase changed into steam by the boilers 50a and 50b. That is, the economizer 40 and the boilers 50a and 50b may be arranged in series based on the flow of fresh water in the fresh water inlet line L20.

On the other hand, the exhaust of the fuel cell 30 is delivered to the economizer 40 through the fuel cell exhaust line L11, and after being cooled while heating fresh water in the economizer 40, the fuel cell exhaust line extended from the economizer 40 It can be discharged to the outside through a stack, a vent mast, etc. along (L11).

The boilers 50a and 50b change the fresh water heated by the economizer 40 into steam using exhaust exhaust from the power generation engines 20a and 20b. As described above, the economizer 40 and the boilers 50a and 50b are provided in series based on the flow of fresh water, and the fresh water is heated by high-temperature water in the economizer 40 and then converted into steam in the boilers 50a and 50b. It can be changed and supplied to the steam consumer 100. Here, the steam consumer 100 may be a steam turbine or a vaporizer that heats liquefied gas, but is not particularly limited.

In order to solve the problem that steam is not generated through the exhaust of the fuel cell 30 while placing the fuel cell 30 with less power generation than the power generation engines 20a and 20b as a base load, the economizer 40 and the Furnace boilers 50a and 50b can be provided to ensure steam generation.

At this time, the boilers (50a, 50b) may be allocated to each power generation engine (20a, 20b), the first boiler (50a) and the second power generation engine (20b) for heating fresh water by exhaust of the first power generation engine (20a) A second boiler 50b for heating fresh water by exhaust of the air may be provided, but the first boiler 50a and the second boiler 50b may be disposed in parallel based on the flow of fresh water.

That is, the fresh water is changed to hot water through the economizer 40 and then distributed to the first boiler 50a and the second boiler 50b, and exhaust of the power generation engines 20a and 20b from the boilers 50a and 50b. It can be changed to steam through. To this end, the fresh water inlet line L20 is branched to the first boiler 50a and the second boiler 50b via the economizer 40 to distribute fresh water, and the first boiler 50a and the second In order to supply the steam generated by the boiler 50b to the steam consumer 100, the steam supply line L21 may be connected from the boilers 50a and 50b to the steam consumer 100.

The exhaust of the power generation engines 20a, 20b used in the boilers 50a, 50b may have a temperature of about 400 degrees higher than that of the fuel cell 30, and the flow rate may also be higher than the exhaust of the fuel cell 30. , It is not limited to this.

For example, when the flow rate of exhaust is insufficient according to the load of the power generation engines 20a and 20b, steam generation may not be achieved only by exhausting the fuel cell 30 and exhausting the power generation engines 20a and 20b. Accordingly, the boilers 50a and 50b may be provided with a burner 51 that directly burns gaseous fuel to convert fresh water into steam.

The burner 51 can generate 1,000 degrees or more, which is higher than the exhaust (about 400 degrees) of the power generation engines 20a and 20b while burning gas fuel, and thus, even if the load of the power generation engines 20a and 20b is reduced, You can generate enough.

The liquefied gas supply line L1 / evaporation gas supply line L2 connected to the power generation engines 20a and 20b and the fuel cell 30 described above may be connected to the burners 51 in the boilers 50a and 50b. . That is, the boilers 50a and 50b can change hot water into steam by using exhaust or gas fuel from the power generation engines 20a and 20b as a heat source, and the gas fuel supplied to the burner 51 is the power generation engine 20a, According to the load of 20b), the opening degree of the liquefied gas supply valve V1, etc. may be controlled.

The boilers 50a and 50b generate steam using heat sources having different temperatures as described above, and exhaust exhaust of the power generation engines 20a and 20b and exhaust of the burner 51 may be discharged. In this case, the power generation engine exhaust line L10 for discharging the exhaust of the power generation engines 20a and 20b and the burner exhaust line L12 for discharging the exhaust of the burner 51 are independently extended from the boilers 50a and 50b. There may be, and, similar to the contents of the fuel cell exhaust line L11 extending via the economizer 40, it may be connected to a stack or the like to discharge exhaust to the outside.

At this time, the exhaust of the boilers 50a, 50b (in this specification, the exhaust of the power generation engines 20a and 20b and the exhaust of the burner 51 are included) and the exhaust of the economizer 40 are mixed and discharged through a stack or the like, It can be mixed naturally while being discharged from the stack.

As described above, in this embodiment, the exhaust of the fuel cell 30 and the exhaust of the power generation engines 20a and 20b are utilized for the production of steam, but the fuel cell 30 has less power than the power generation engines 20a and 20b. It is possible to ensure steam production by arranging the economizer 40 and the boilers 50a and 50b in series while always operating at the base load.

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

Hereinafter, the present embodiment will be described mainly in terms of differences compared to the previous embodiment, and this is the same in other embodiments below.

Referring to FIG. 2, in the electric propulsion system 1 according to the second embodiment of the present invention, exhaust from the burner 51 may be used for heating gaseous fuel.

As described in the previous embodiment, the boilers 50a and 50b have a burner 51 that converts fresh water into steam by burning gaseous fuel. The exhaust of the burner 51 and the exhaust of the power generation engines 20a and 20b are independently Can be discharged.

At this time, since the exhaust of the burner 51 is relatively hotter than the exhaust of the power generation engines 20a and 20b, when the exhaust of the burner 51 and the exhaust of the power generation engines 20a and 20b are mixed and discharged, the exhaust of the burner 51 The included thermal energy is discarded.

Therefore, in this embodiment, heat further included in the exhaust of the burner 51 can be recovered compared to the exhaust of the power generation engines 20a and 20b, and specifically, the exhaust of the burner 51 is the boilers 50a and 50b. After being discharged independently from the exhaust of the power generation engines 20a and 20b and then used for heating gaseous fuel, it may be treated separately or mixed with the exhaust of the power generation engines 20a and 20b to be discharged.

The gas fuel heated by the exhaust of the burner 51 may be gas fuel supplied to the fuel cell 30. A reformer 31 is provided between the liquefied gas storage tank 10 and the fuel cell 30, and the present embodiment may further include a heat exchanger 311 for heating gaseous fuel flowing into the reformer 31. .

At this time, the heat exchanger 311 heats the gaseous fuel using the exhaust of the burner 51 to evaporate when the gaseous fuel is a liquefied gas, and increase the temperature when the gaseous fuel is an evaporation gas.

Of course, the exhaust of the burner 51 may be utilized for heating the gas fuel supplied to the power generation engines 20a and 20b, but the use of the burner 51 means that there is no operation of the power generation engines 20a, 20b or a low load. In this case, since the fuel cell 30 always operates with a constant amount of power generation, the exhaust of the burner 51 can be mainly used for heating the gaseous fuel supplied to the fuel cell 30.

As described above, in this embodiment, the waste heat contained in the exhaust of the burner 51 discharged from the boilers 50a and 50b is recovered and utilized for gas fuel heating of the fuel cell 30, thereby improving reforming efficiency and energy use efficiency. I can make it.

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

3, the electric propulsion system 1 according to the third embodiment of the present invention is applied to a ship (not limited to an oil carrier) having an oil storage tank 11 for storing oil, An oil unloading pump 111 is allocated to the storage tank 11 and an oil unloading line L30 is connected.

The oil unloading pump 111 is provided to unload the oil in the oil storage tank 11. The oil loading and unloading pump 111 can implement oil pumping using a rotational force. In particular, the oil unloading pump 111 of this embodiment uses electricity generated by the fuel cell 30 and the power generation engines 20a, 20b. Can be operated.

Oil unloading is performed when the ship is moored, but in the conventional case, the amount of power generation has not been enough to cover the operation of the oil unloading pump 111 in the state in which the ship is moored. For this reason, conventionally, the boilers 50a and 50b were driven, and the oil loading and unloading pump 111 was operated through steam generated from the boilers 50a and 50b. That is, the conventional oil loading and unloading pump 111 is provided in a type that operates using steam.

However, in the present invention, since the fuel cell 30 is used as a base load and electricity is produced by the power generation engines 20a and 20b, sufficient electricity can be produced at anchor. Accordingly, the oil loading and unloading pump 111 of the present invention may be provided in a type that operates using electricity instead of steam.

In this case, the present invention does not need to separately provide auxiliary boilers 50a and 50b for driving the oil loading and unloading pump 111, and it is also necessary to solve the problem of treatment of exhaust gas generated while operating the boilers 50a and 50b during anchoring. There is no advantage.

In particular, since environmental regulations are reinforced in the berth area, the treatment of exhaust of the boilers 50a and 50b is a big problem, and the present invention can eliminate the source of such a problem. In addition, when berthing, gas fuel, etc., are insufficient due to unloading, so the operating load of the boilers 50a, 50b may not be guaranteed.If oil fuel is used for oil unloading, the unloading target will be exhausted, causing complaints of cargo owners. However, in the present invention, by using the fuel cell 30 to set the oil loading and unloading pump 111 as an electric operation type, all of the above problems can be solved.

This embodiment further includes a heating unit 60. The heating unit 60 heats the oil in the oil storage tank 11 before unloading the oil. Unlike liquefied gas, oil can be stored in a liquid state at room temperature, and in this case, oil may interfere with unloading as the flow is hindered as the viscosity of the oil at low temperature increases. Therefore, in this embodiment, the unloading efficiency can be increased by lowering the viscosity by heating the oil before unloading.

For this, the heating unit 60 may be provided in the form of a coil inside the oil storage tank 11, and increase the temperature of the oil stored in the oil storage tank 11 while circulating a material having a relatively high temperature compared to the oil through the coil. I can.

However, in the conventional case, steam generated by the boilers 50a and 50b was used to lower the viscosity of the oil. At this time, as the steam condenses while exchanging heat with oil, heat energy loss of about 10% occurs during condensation.

In order to solve this heat energy loss, the present invention may use thermal oil instead of steam. In this case, the hot oil may be a material having a different component from the oil, and is used by the heating unit 60 without a phase change.

The heating unit 60 heats the hot oil and heats the oil using the heated hot oil, and the heating unit 60 can heat the hot oil using exhaust from the boilers 50a and 50b. At this time, the exhaust of the boilers 50a and 50b may be exhaust of the burner 51 or exhaust of the power generation engines 20a and 20b.

The heating unit 60 includes a hot oil heater 61 and a hot oil heater 62. The hot oil heater 61 may heat the hot oil by heat exchange between the exhaust of the boilers 50a and 50b and the hot oil, and while a plurality of hot oil heaters 61 are provided in parallel, each hot oil heater 61 is provided with the boiler 50a, It can be allocated every 50b).

A hot oil supply line (L40) may be provided to distribute hot oil via a hot oil tank (not shown) and a hot oil pump (not shown) to the hot oil heater 61, and heated by the hot oil heater 61 The hot oil is mixed along the hot oil supply line L40 and then flows into the hot oil heater 62.

The hot oil heater 62 is provided downstream of the hot oil heater 61 to heat the hot oil. The hot oil heater 62 may use fuel or electricity, and finally heat the hot oil to a temperature required for heating the oil.

However, the hot oil heated by the hot oil heater 62 may still be in a liquid state, and therefore, the hot oil heater 61, the hot oil heater 62, the coil provided in the oil storage tank 11, etc. You can pass through.

As described above, in this embodiment, the auxiliary boilers 50a and 50b can be omitted by providing an oil loading and unloading pump 111 that operates with electricity instead of steam, and heats the hot oil other than steam using the exhaust of the boilers 50a and 50b. It can be used to control the viscosity of oil and solve the problem of heat energy loss that occurs when condensing steam.

In the case of the first to third embodiments described above, it is a system exclusively for liquefied gas that generates electricity using liquefied gas as a fuel, and in the fourth embodiment described below, liquefied gas or oil is used as a fuel to produce electricity. It is a gas/oil hetero-fuel system.

However, for the first to third embodiments, a configuration for supplying oil as a fuel to be described below may be added, and conversely, a configuration for supplying oil as a fuel for the fourth embodiment described below may be omitted. Of course.

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

Referring to FIG. 4, in the electric propulsion system 1 according to the fourth embodiment of the present invention, the power generation engines 20a and 20b are provided so as to use oil fuel in addition to gas fuel.

To this end, a liquefied gas storage tank 10 for storing gaseous fuel and an oil storage tank 11 for storing oil fuel are provided on the ship. In the liquefied gas storage tank 10, power generation engines 20a, 20b and fuel A liquefied gas supply line (L1) (or boil-off gas supply line (L2)) is provided as the battery 30, and an oil supply line (L3) is added from the oil storage tank 11 to the power generation engines 20a and 20b. It is prepared with.

An oil supply valve V3 is provided in the oil supply line L3, and the supply amount of oil fuel can be adjusted in conjunction with the supply amount of gas fuel. Also, as in the liquefied gas supply line L1, the oil supply line L3 may be connected to the burners 51 of the boilers 50a and 50b.

However, in this embodiment, the fuel cell 30 may be driven only with gas fuel. In this case, as in the previous embodiments, since the present embodiment does not supply the oil fuel to the fuel cell 30, it is used to desulfurize the oil fuel. Configuration may not be provided.

In this embodiment, the boilers 50a and 50b produce steam by using the exhaust of the power generation engines 20a and 20b or the combustion heat of the burner 51, and the burner 51 uses the combustion heat of gas fuel or oil fuel. I can.

However, when the boiler (50a, 50b) uses the exhaust of the power generation engines (20a, 20b), the temperature of the heat applied to the fresh water is around 400 degrees, whereas when using the combustion heat of the burner (51) it can be around 1,000 degrees. , A difference may occur depending on the type of fuel consumed by the burner 51.

That is, the temperature of the heat supplied to fresh water varies according to which heat source the boilers 50a and 50b use. In this embodiment, steam generation can be efficiently controlled in consideration of this.

For example, when the first boiler (50a) and the second boiler (50b) respectively allocated to the first power generation engine (20a) and the second power generation engine (20b) are provided, the first boiler (50a) and the second boiler ( Depending on the type of heat source for heating fresh water in 50b), the amount of fresh water distribution in the fresh water inlet line L20 or the amount of steam mixing in the steam supply line L21 may be controlled by the controller.

Specifically, the control unit is a fresh water inlet valve V20 provided upstream of the first boiler 50a or the second boiler 50b in the fresh water inlet line L20 for distributing hot water to the plurality of boilers 50a and 50b. Can be controlled, and/or a downstream of the first boiler 50a or the second boiler 50b in the steam mixing line that is extended from the plurality of boilers 50a, 50b and then joined to the steam consumer 100 It is possible to control the steam mixing valve (V21) provided in.

That is, in this embodiment, as the plurality of boilers 50a and 50b generate steam from different heat sources, the steam generation capacity may not be the same, so the fresh water supplied to each boiler 50a, 50b using the control unit By controlling the flow rate of / the flow rate of the steam discharged from each of the boilers (50a, 50b), it is possible to match the temperature / flow rate required by the steam consumer 100.

When the first boiler 50a and the second boiler 50b generate steam from different heat sources, the control unit includes the fresh water inflow amount/steam mixing amount in any one boiler 50a, 50b using the burner 51, It can be controlled to be relatively larger than the fresh water inflow amount/steam mixing amount in other boilers 50a and 50b using exhaust from the power generation engines 20a and 20b.

Alternatively, if the power generation amount of the first power generation engine 20a and the second power generation engine 20b is different, and there is a difference in the specifications of the first boiler 50a and the second boiler 50b, the controller Even when the boilers 50a and 50b do not use different heat sources, depending on the temperature or flow rate of the heat sources for heating fresh water in the first boiler 50a and the second boiler 50b, the fresh water distribution amount or the steam mixing amount Can be controlled.

In addition, the control unit may control the fresh water distribution amount or the steam mixing amount according to the operation profile of the power generation engines 20a and 20b during anchoring or operation of the ship. The operation profile of the power generation engines 20a and 20b refers to whether the power generation engines 20a and 20b are operated, which means whether exhaust of the power generation engines 20a and 20b is generated or whether the burner 51 needs to be operated, and power generation. It may include information such as the displacement of the engines 20a and 20b / the movable load of the power generation engines 20a and 20b which means the movable load of the burner 51.

As described above, the present embodiment generates steam through a plurality of boilers 50a and 50b that have different specifications and can use different heat sources, while efficiently controlling the amount of steam generated to operate the steam demander 100. Can keep it stable.

Hereinafter, based on the fourth embodiment in which the supply of oil fuel is added, the differences in each embodiment will be described in detail.

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

5, the electric propulsion system 1 according to the fifth embodiment of the present invention includes a heat exchanger 311 for heating gaseous fuel flowing into the reformer 31, and the heat exchanger 311 The gas fuel can be heated using fresh water heated in the economizer 40.

In the case of the above second embodiment, the heat exchanger 311 heated the gas fuel by using the exhaust of the burner 51. In contrast, this embodiment is a liquid phase heated by the exhaust of the fuel cell 30 in the economizer 40. You can use hot water.

To this end, in the present embodiment, the fresh water branch line L22 may be branched from the fresh water inlet line L20. The fresh water branch line L22 is partially branched from the fresh water inlet line L20 and is provided to pass through the heat exchanger 311.

Specifically, the fresh water branch line L22 is branched from the downstream of the economizer 40 in the fresh water inlet line L20 and passes through the heat exchanger 311, and then the upstream of the boiler 50a, 50b in the fresh water inlet line L20. Is joined by At this time, the fresh water branch line L22 is provided with a fresh water branch valve V22 for adjusting the flow rate of the branched fresh water, and the fresh water branch valve V22 is controlled by a controller (not shown).

The controller may control the fresh water flow rate of the fresh water branch line L22 in consideration of the flow rate of gas fuel supplied to the fuel cell 30 or the fresh water flow rate of the fresh water inlet line L20. The controller may control the fresh water branch valve V22 or the fresh water pump 41 provided in the fresh water inlet line L20. In particular, the controller may control the fresh water branch valve to prevent freezing of fresh water in the heat exchanger 311. V22) or the fresh water pump 41 can be controlled.

The fresh water is heated by the exhaust of the fuel cell 30 in the economizer 40, but does not change phase and may be changed to hot water.For example, the fresh water may have a temperature of about 90 degrees downstream of the economizer 40. .

At this time, if the gas fuel is heated using hot water, there is a risk of condensation as the hot water cools to 0 degrees or less due to the low temperature of the gas fuel.The control unit speeds up the flow rate of the hot water or increases the flow rate of the hot water. It is possible to prevent freezing of high-temperature water in the heat exchanger 311 through control, such as being controlled.

In addition, when fresh water is delivered to the heat exchanger 311, the temperature of the fresh water flowing into the boilers 50a and 50b can be transferred to the heat exchanger 311 to be lowered by the flow rate of the fresh water cooled by gas fuel, so the boiler 50a , 50b) may adjust the movable load of the burner 51 according to the flow rate of fresh water delivered to the heat exchanger 311.

That is, when the flow rate of fresh water passing through the heat exchanger 311 increases, the operation load of the burner 51 is increased, so that even if some of the hot water is cooled by gas fuel, the boilers 50a and 50b can sufficiently generate steam. have.

As described above, in this embodiment, the gas fuel supplied to the fuel cell 30 is heated by using the high-temperature water discharged from the economizer 40, thereby improving energy efficiency.

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

Referring to FIG. 6, the electric propulsion system 1 according to the sixth embodiment of the present invention operates the fuel cell 30 with a constant base load, while the power generation engines 20a and 20b are operated with a variable power generation amount. It can be operated as an auxiliary load.

The fuel cell 30 has a power generation amount of about 1 MW smaller than that of the power generation engines 20a and 20b and is always operated to maintain constant production of electricity. To this end, in this embodiment, the fuel cell 30 stores liquefied gas. The liquefied gas in the tank 10 is consumed.

Liquefied gas is stored in the liquefied gas storage tank 10, and boil-off gas is generated by external heat penetration. The storage amount of liquefied gas varies only by consumption, but the storage amount of boil-off gas may vary not only by consumption but also by factors that are difficult to calculate, such as external heat penetration.

Therefore, when the fuel cell 30 uses the boil-off gas as the main fuel, the load of the fuel cell 30 may need to be adjusted. In this embodiment, the fuel cell 30 consumes the liquefied gas and the amount of power generation is constant. Keep it.

On the other hand, the power generation engines 20a and 20b may be operated with an auxiliary load in which the amount of power generation varies while consuming the boil-off gas generated in the liquefied gas storage tank 10. In this case, the sub-load does not mean that the amount of power generation is small, but it means that the amount of power generation is added in addition to the amount of power generation of the fuel cell 30, which is a base load.

In this way, only the liquefied gas supply line (L1) is connected from the liquefied gas storage tank 10 to the fuel cell 30, and the fuel cell 30 does not use oil fuel as well as boil-off gas. (32) can be omitted.

On the other hand, from the liquefied gas storage tank 10 to the power generation engines 20a and 20b, the boil-off gas supply line (L2) and the oil supply line (L3) may be connected, and the oil supply valve (V3) is It is adjusted to reduce load fluctuations of the power generation engines 20a and 20b.

For example, the first power generation engine 20a having a power generation amount corresponding to the amount of electricity required when the ship is moored may use oil together so that the power generation amount can be operated constantly while consuming boil-off gas while the ship is at anchor.

In addition, the boil-off gas supply line (L2) is connected from the liquefied gas storage tank (10) to the burner (51) of the boiler (50a, 50b), and the boiler (50a, 50b) is a boil-off gas similar to the power generation engines (20a, 20b). The amount of steam generated can be varied while consuming the effluent.

As described above, in this embodiment, the fuel cell 30 uses liquefied gas in order to keep the amount of power generation of the fuel cell 30 constant, and the boil-off gas having a different flow rate is converted into the power generation engines 20a, 20b and the burner 51. It is possible to ensure durability of the fuel cell 30 by consuming it on the back so that the movable load of the fuel cell 30 does not change.

The fuel cell 30, which is an SOFC operating in a high-temperature environment, may change the internal temperature when the load is changed and the durability may decrease. However, this embodiment solves such a problem to ensure the life of the fuel cell 30.

However, in this embodiment, the fuel cell 30 is limited to not using the boil-off gas, but the power generation engines 20a and 20b can use the boil-off gas while using the liquefied gas.

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

Referring to FIG. 7, the electric propulsion system 1 according to the seventh embodiment of the present invention supplies oil fuel stored in the oil storage tank 11 to the fuel cell 30.

Since the fuel cell 30 is configured to generate electricity using hydrogen, in order to supply liquefied gas made of methane to the fuel cell 30, a reforming operation to separate carbon from methane is required, so the reformer 31 Will be equipped.

Furthermore, in order to supply the oil fuel to the fuel cell 30, a reforming operation of removing the sulfur component contained in the oil fuel and separating the carbon bonded to hydrogen is required.

To this end, in this embodiment, in the oil supply line L3 connected from the oil storage tank 11 to the fuel cell 30, the desulfurizer 32 and the reformer 31 are sequentially arranged upstream of the fuel cell 30. Can be prepared. At this time, the reformer 31 may be a configuration capable of simultaneously/simultaneously implementing reforming of gas fuel and reforming of oil fuel, and is a separate type provided in the liquefied gas supply line (L1) or the oil supply line (L3) or integrally. Can be provided.

The desulfurizer 32 desulfurizes the oil fuel supplied to the fuel cell 30, and the desulfurization principle can use a physical/chemical method widely known in the art without limitation.

In addition, the desulfurizer 32 may be provided integrally with a pre-reformer (not shown), and in this case, the reformer 31 may finally reform the developed oil fuel.

In this embodiment, it is noted that a desulfurizer 32 or the like is provided to supply oil fuel in addition to gas fuel to the fuel cell 30, and the eighth embodiment described below is based on this embodiment.

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

Referring to FIG. 8, in the electric propulsion system 1 according to the eighth embodiment of the present invention, the desulfurizer 32 may desulfurize oil fuel heated by using fresh water heated in the economizer 40.

Since the temperature of the oil fuel stored in the oil storage tank 11 may be room temperature, it is widely known in the field that it is desirable to increase the temperature to a temperature of around 80° C. to increase efficiency during desulfurization.

In consideration of this, in this embodiment, the oil fuel to be desulfurized is heated, but hot water discharged from the economizer 40 can be utilized for heating the oil fuel.

At this time, in this embodiment, a heater 321 for heating the oil fuel flowing into the desulfurizer 32 with hot water may be provided upstream of the desulfurizer 32 or inside the desulfurizer 32, and the oil to be desulfurized. A fresh water delivery line L23 branched from the downstream of the economizer 40 to the heater 321 in the fresh water inlet line L20 for heating the fuel may be provided.

Alternatively, in this embodiment, the heater 321 is omitted and the fresh water delivery line (L23) is directly connected to the desulfurizer 32 to supply the hot water heated by the economizer 40 to the desulfurizer 32, (32) may have its own oil fuel heating and desulfurization at the same time.

Since the high-temperature water used for heating the oil fuel to be desulfurized has a high possibility of containing foreign substances such as sulfur, it may be preferable not to change it to steam and supply it to the steam consumer 100. Accordingly, the fresh water delivery line L23 may be provided so that it is branched from the fresh water inlet line L20 and does not merge into the fresh water inlet line L20.

In addition, the fresh water bypass line is partially branched from the fresh water inlet line L20 to bypass the economizer 40 so that most of the heat transferred from the economizer 40 to the fresh water can be transferred to the oil fuel along the fresh water transfer line L23. (L24) can be provided.

That is, the hot water is delivered to the heater 321 along the fresh water delivery line (L23), and the fresh water bypass line from the fresh water inlet line (L20) upstream of the economizer 40 to generate steam in the boilers (50a, 50b). Fresh water can be sufficiently delivered to the boilers 50a and 50b along L24).

At this time, the flow rate of fresh water supplied to the boilers 50a and 50b can be controlled by the fresh water bypass valve V24, and the fresh water bypass valve V24 provided in the fresh water bypass line L24 is supplied to the fuel cell 30. As the flow rate of the oil fuel is controlled by the controller, the flow rate of fresh water delivered to the boilers 50a and 50b along the fresh water bypass line L24 may be appropriately set.

However, when the fresh water bypassing the economizer 40 flows into the boilers 50a, 50b, a relatively large amount of heating is required in preparation for the inflow of hot water, so the boilers 50a, 50b can use the burner 51. have.

If a fresh water bypass line (L24) is provided, a part of the hot water is transferred to the fresh water delivery line (L23) and the rest is transferred to the boilers (50a, 50b), but unlike the above case, this embodiment is a fresh water inlet line. It is also possible to distribute and connect the (L20) itself to the economizer 40 and the boilers 50a and 50b.

That is, the fresh water inlet line L20 distributes fresh water to the economizer 40 and the boilers 50a and 50b, respectively, and the fresh water delivery line L23 may extend from the downstream of the economizer 40 to the heater 321, etc. . In this case, in consideration of the flow rate of the oil fuel supplied to the fuel cell 30, the amount of fresh water distribution in the fresh water inlet line L20 may be controlled by the controller.

As described above, the present embodiment can maximize the power generation efficiency of the fuel cell 30 by increasing the desulfurization efficiency by utilizing the high-temperature water to heat the desulfurized oil fuel and prevent environmental pollution.

In addition to the above-described embodiments, the present invention encompasses all embodiments generated by a combination of at least two or more of the above embodiments or a combination of at least one or more of the above embodiments and known techniques.

As an example, a ninth embodiment in which the eighth embodiment shown in FIG. 8 and the second embodiment shown in FIG. 2 are partially combined may be further included. In the ninth embodiment, the desulfurizer 32 can desulfurize the heated oil fuel using exhaust from the burner 51.

In order to improve the desulfurization efficiency, it is preferable to heat the oil higher than the temperature of the oil stored in the oil storage tank 11, as described above. In the ninth embodiment, the burner 51 is exhausted for heating gas fuel. With reference to the second embodiment in which is utilized, the exhaust of the burner 51 can be utilized for heating oil fuel to be desulfurized.

At this time, a heater 321 that heats the oil fuel flowing into the desulfurizer 32 by using the exhaust of the burner 51 is used, or the desulfurizer 32 itself receives the exhaust of the burner 51, and the burner ( It is similar to the contents of the eighth embodiment that oil fuel can be heated and desulfurized at the same time by using the exhaust of 51).

Of course, in addition to the ninth embodiment described above, any combination of features of the above-described embodiment may be included in the scope of the present invention.

Although the present invention has been described in detail through specific examples, this is for explaining the present invention in detail, and the present invention is not limited thereto, and within the technical scope of the present invention, those of ordinary skill in the art It would be clear that the transformation or improvement is possible.

All simple modifications to changes of the present invention belong to the scope of the present invention, and the specific scope of protection of the present invention will be made clear by the appended claims.

1: electric propulsion system 10: liquefied gas storage tank
11: oil storage tank 111: oil handling pump
20a: first power generation engine 20b: second power generation engine
30: fuel cell 31: reformer
311: heat exchanger 32: desulfurizer
321: heater 40: economizer
41: fresh water pump 50a: first boiler
50b: second boiler 51: burner
60: heating unit 61: hot oil heater
62: hot oil heater 100: steam demand
L1: liquefied gas supply line V1: liquefied gas supply valve
L2: Boil-off gas supply line V2: Boil-off gas supply valve
L3: Oil supply line V3: Oil supply valve
L10: Power generation engine exhaust line L11: Fuel cell exhaust line
L12: burner exhaust line L20: fresh water inlet line
V20: fresh water inlet valve L21: steam supply line
V21: steam mixing valve L22: fresh water branch line
V22: fresh water branch valve L23: fresh water delivery line
L24: clear water bypass line V24: clear water bypass valve
L30: Oil unloading line L40: Hot oil supply line

Claims (9)

An electric propulsion system having a power generation engine and a fuel cell that consumes gas fuel from a liquefied gas storage tank mounted on a ship and generates electricity for propulsion of the ship,
It includes a boiler having a burner that converts fresh water into steam by burning gas fuel,
The fuel cell,
While consuming the liquefied gas from the liquefied gas storage tank, the amount of power generation is operated with a constant base load,
A desulfurizer is omitted between the liquefied gas storage tank and the fuel cell,
The boiler,
The amount of steam generated is varied by consuming the boil-off gas generated in the liquefied gas storage tank,
The burner consumes oil to control the amount of steam generated,
The power generation engine,
While preferentially consuming the boil-off gas generated in the liquefied gas storage tank, it is operated with an auxiliary load whose power generation amount is variable,
Electric propulsion system, characterized in that to reduce a variable amount by consuming liquefied gas or oil according to the amount of boil-off gas generated in the liquefied gas storage tank. delete The method of claim 1,
An electric propulsion system, further comprising a reformer provided between the liquefied gas storage tank and the fuel cell to separate hydrogen from the liquefied gas. delete The method of claim 1, wherein the fuel cell,
Electric propulsion system, characterized in that it has a relatively small amount of power generation than the power generation engine. The method of claim 1, wherein the power generation engine,
Electric propulsion system, characterized in that consisting of two or more power generation engines having different amounts of power generation. The method of claim 1,
The first power generation engine has a power generation amount corresponding to the amount of electricity required when the ship is anchored,
The fuel cell and the power generation engine, wherein the electric propulsion system, characterized in that having a total amount of power corresponding to the amount of electricity required for the operation of the ship. The method of claim 7, wherein the first power generation engine,
Electric propulsion system, characterized in that when the ship is anchored, the amount of power generation is constant while consuming the boil-off gas generated from the liquefied gas storage tank. A ship comprising the electric propulsion system according to any one of claims 1, 3 and 5 to 8.

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