KR101359950B1 - Fuel Supply System In Ship Loaded Fuel Cell - Google Patents

Abstract

A fuel cell system of a fuel cell mounted vessel is disclosed. A fuel cell system of a fuel cell equipped ship of the present invention is a power operation system of a liquefied natural gas carrier, the storage tank is provided in the hull and the liquefied natural gas (LNG) is stored therein; A fuel cell unit provided in the hull and using a boil-off gas generated from a storage tank as a fuel; And a medium pressure buffer unit configured to store the liquefied natural gas supplied from the storage tank in a medium pressure state and supply the stored liquefied natural gas to the fuel cell unit when the supply of the fuel supplied to the fuel cell unit is stopped.

Description

Fuel Supply System In Ship Loaded Fuel Cell}

The present invention relates to a fuel cell system of a ship equipped with a fuel cell, and more particularly, to store a part of the liquefied natural gas in a medium pressure state and to store the liquefied natural gas stored at the time of supply of fuel supplied to the fuel cell unit as the fuel cell unit. The present invention relates to a fuel cell system of a ship equipped with fuel cells.

A fuel cell is a power generation device that converts chemical energy of reactants (hydrogen and oxygen) directly into electrical energy by an electrochemical reaction, and is excellent in environmental harmony and high power generation efficiency is expected.

Such fuel cells are classified into a low-temperature type and a high-temperature type, and representative examples of the high-temperature type include a molten carbonate fuel cell (MCFC) and a solid oxide fuel cell.

The characteristics of the high temperature type fuel cell can be summarized as follows. MCFC can use various kinds of fuels such as natural gas and coal gas. It can produce electricity by electrochemical reaction that converts fuel directly into electricity at about 650 ° C without combustion process. .

In the case of a solid oxide fuel cell, it operates at a high temperature of 1000 ° C or higher and uses a variety of fuels such as natural gas, coal gas, and methanol. Therefore, combined power generation using high temperature and high pressure steam generated at the rear end of the fuel cell is possible.

In addition, since there is no combustion process and electricity is generated directly from fuel, it is attracting attention as next generation power generation because there is little noise and air pollutant emission.

The unit cell of such an MCFC includes an anode and a cathode at which an electrochemical reaction takes place, a separator for forming a flow path for a fuel gas and an oxidant gas, a collecting plate for collecting charges, An electrolyte plate made in the form of a sheet and a matrix for accommodating the molten carbonate for the sake of convenience. When the fuel gas is supplied to the anode and the oxidant gas is supplied to the cathode, an electrochemical reaction occurs at each electrode, Power is obtained.

1 is a view schematically showing an example of a fuel cell system of a conventional fuel cell-equipped ship to which such a fuel cell is applied to an LNG carrier.

First, a state in which the evaporative gas is normally supplied to the fuel cell 13 will be described. The boil-off gas generated in the storage tank is supplied to the humidifier 11 through the connection flow path L2. At the same time, the evaporation gas is compressed through the compressor 21 and then stored in the evaporation gas storage tank 23 via the cooler 22. The evaporation gas stored in the evaporation gas storage tank 23 is supplied to the humidifier 11 .

The evaporated gas supplied to the humidifier 11 is mixed with the liquid vaporized in the humidifier 11 to become a wet evaporated gas. The moisture evaporated gas is supplied to the reformer 12, reformed into hydrogen and carbon dioxide in the reformer 12, and the reformed hydrogen and carbon dioxide are supplied to the fuel cell 13.

The anode of the fuel cell 13 receives hydrogen and carbon dioxide and acts on the oxidizing gas containing oxygen supplied to the cathode through the blower 14 and the air heater 15 to generate electricity by an electrochemical reaction.

On the other hand, when the supply of the boil-off gas through the connection passage (L2) is stopped, the sensor 24 recognizes this and sends a signal to the controller. Typically, when loading and unloading of LNG is carried out, all equipment and piping connected to LNG storage tank except piping and equipment for LNG loading and unloading are locked according to Cargo Operation Manual, and LNG and BOG The line is locked, and the evaporation gas supply is stopped. At this time, the control unit opens the valve provided in the buffer connection channel based on the above-mentioned signal, and the evaporation gas stored in the evaporation gas storage tank 23 is regulated in temperature and pressure through the regulator 25 and the heater 26 And is supplied to the humidifier 11. The evaporated gas supplied to the humidifier 11 is used as fuel for the fuel cell 13 after passing through the humidifier 11 and the reformer 12 as described above.

The buffer fuel system of the conventional fuel cell system compresses and stores boil-off gas (BOG) generated during the operation of LNG carriers, and continuously supplies the boil-off gas to the fuel cell when the fuel supply from the storage tank is stopped. It was possible to operate it, but by storing the boil-off gas at a high pressure of 200 bar or more, the arrangement of the ship was very limited according to the high pressure regulation of the ship. In addition, the installation of the high pressure compressor, high pressure tank, safety equipment, such as high-pressure evaporative gas storage is provided with a lot of expensive installation costs, the risk of the high-pressure gas storage problem.

It is an object of the present invention to provide a buffer gas unit for a marine fuel cell which can be continuously operated without stopping the operation of the fuel cell even when the supply of fuel to the fuel cell is interrupted, To solve the conventional problems that require a large amount of equipment cost.

According to an aspect of the present invention, as a power operation system of a liquefied natural gas carrier,

A storage tank provided in the hull and storing liquefied natural gas (LNG) therein;

A fuel cell unit provided in the hull and using a boil-off gas generated in the storage tank as a fuel; And

Liquefied natural gas supplied from the storage tank is stored in a medium pressure state, the fuel cell mounting comprising a medium-pressure buffer unit for supplying the liquefied natural gas stored when the supply of the fuel supplied to the fuel cell unit to the fuel cell unit A fuel cell system of a ship is provided.

The medium pressure buffer unit is provided in the hull and pumps the liquefied natural gas supplied from the storage tank to transfer to a medium pressure state, a medium pressure tank for storing the medium pressure liquefied natural gas transferred from the pump, and It may include a vaporizer for vaporizing the liquefied natural gas of the medium pressure stored in the medium pressure tank, and a valve provided in the buffer connection flow path connecting the carburetor and the fuel cell unit and opening and closing the buffer connection flow path.

The medium pressure buffer unit may further include a heat exchanger for liquefying the buffer boil-off gas generated in the medium pressure tank by heat exchange with the liquefied natural gas supplied from the storage tank.

The liquefied natural gas passing through the heat exchanger may be introduced into the fuel cell unit when evaporated by heat exchange with the buffer boil-off gas, and may be recovered to the storage tank in the liquid state.

The medium pressure buffer unit may include a sensor provided in a connection flow path connecting the storage tank and the fuel cell unit to detect whether boil-off gas generated in the storage tank is supplied to the connection flow path, and a signal detected from the sensor. It may further include a control unit for opening and closing the valve.

The fuel cell unit includes a humidifier for humidifying the boil-off gas supplied from the storage tank or the medium pressure buffer unit, a reformer for reforming the boil-off gas into hydrogen and carbon dioxide, and the hydrogen and carbon dioxide and cathode supplied to the anode. A fuel cell for generating electricity by an electrochemical reaction of the supplied oxygen, a blower for supplying external air to the fuel cell, and an air heater for heating the air supplied to the fuel cell through the blower Can be.

According to another aspect of the present invention, in the fuel supply method of the fuel cell for ships using the boil-off gas provided in the hull and stored in a storage tank in which liquefied natural gas is stored,

A portion of the liquefied natural gas stored in the storage tank is stored at a medium pressure state, and when the supply of the boil-off gas supplied to the fuel cell is stopped, the medium-pressure liquefied natural gas stored in the storage tank is vaporized and supplied to the fuel cell to stop the fuel cell. Provided is a fuel supply method of a fuel cell equipped ship, characterized in that it is operated without.

Embodiments of the present invention can continue to operate without stopping the fuel cell even when the supply of fuel to the fuel cell is stopped, thereby improving the availability of the fuel cell, and stores the liquefied natural gas at medium pressure As a result, the ship's high pressure requirements are not complied with, so the onboard arrangement is relatively free, and the cost of installing additional equipment can be reduced.

1 is a view schematically showing an example of a fuel cell system of a conventional fuel cell-equipped ship.
2 is a view schematically showing a fuel cell system of a fuel cell equipped ship according to an embodiment of the present invention.

In order to fully understand the present invention, operational advantages of the present invention, and objects achieved by the practice of the present invention, reference should be made to the accompanying drawings and the accompanying drawings which illustrate preferred embodiments of the present invention.

Hereinafter, the present invention will be described in detail with reference to the preferred embodiments of the present invention with reference to the accompanying drawings. Like reference symbols in the drawings denote like elements.

2 schematically illustrates a fuel cell system of a fuel cell equipped ship according to an embodiment of the present invention.

As shown in FIG. 2, the fuel cell system of the fuel cell equipped ship of this embodiment is a power operation system of a liquefied natural gas carrier, which is provided in the hull H and stores liquefied natural gas (LNG) stored therein. The tank 100, the fuel cell unit 200 provided in the hull and using a boil-off gas generated in the storage tank 100 as a fuel, and the liquefied natural gas supplied from the storage tank 100 And a medium pressure buffer unit 300 that is stored at an intermediate pressure state and supplies the liquefied natural gas stored at the time of stopping supply of fuel supplied to the fuel cell unit 200 to the fuel cell unit 200.

The liquefaction temperature of the natural gas transported by the liquefied natural gas carrier is very low at about -163 ° C at normal pressure, so it evaporates easily when the temperature rises. The LNG carrier has a cargo hold insulation structure to maintain the liquefied state of the liquefied natural gas, but since the liquefied natural gas is continuously natural vaporized even in the storage tank 100, a considerable amount of BOG is generated. In this case, evaporation gas is generated in the liquefied natural gas storage tank at about 0.05 vol% / day. In the conventional liquefied natural gas carrier, 4 to 6 tons / hour (t) Has been evaporated and gasified. A fuel cell-equipped vessel is a vessel that reforms the evaporated gas and supplies the fuel cell with fuel so as to receive electricity required for the vessel, while reducing the cost of installing an expensive evaporative gas reliquefaction device.

The medium pressure buffer unit 300 is provided in the hull and pumps the liquefied natural gas supplied from the storage tank 100 to be transferred to the medium pressure state, and the medium pressure liquefied natural gas transferred from the pump 310 is stored. In the medium pressure tank 320, the vaporizer 330 for vaporizing the medium pressure liquefied natural gas stored in the medium pressure tank 320, and the buffer connection flow path (B) connecting the vaporizer 330 and the fuel cell unit 200 It is provided and includes a valve 340 for opening and closing the buffer connection flow path (B).

In this embodiment, a portion of the liquefied natural gas stored in the storage tank 100 is pumped by the pump 310 and stored in the medium pressure tank 320 at a medium pressure of about 5 to 10 bar, preferably about 5 bar. The liquefied natural gas stored in the medium pressure tank 320 is stored in the liquid state of the medium pressure, so that the conventional system occupies less volume than the vaporized gas of the gas state stored in the tank. As a result of calculating the required size of the tank for supplying the buffer gas, it was confirmed that the tank size is reduced to about 1/3 when the liquid is stored under the medium pressure state, compared with the case where the high pressure gas is stored at 200 bar. This reduction in tank size is of great significance in terms of efficient utilization of the limited vessel space. In addition, by storing the liquefied natural gas in the medium pressure state, there is an effect that the BOG generation in the medium pressure tank 320 is reduced compared to the normal pressure.

When the supply of the boil-off gas from the storage tank 100 to the fuel cell unit 200 is stopped, the liquefied natural gas stored in the medium pressure tank 320 is phase-changed to a gaseous state in the vaporizer 330, and the valve 340 is opened. Accordingly, the fuel is supplied to the fuel cell unit 200 through the buffer connection channel B.

The medium pressure buffer unit 300 further includes a heat exchanger 350 for liquefying the boil-off gas generated in the medium pressure tank 320 by heat exchange with the liquefied natural gas supplied from the storage tank 100.

The liquefied natural gas passing through the heat exchanger 350 is introduced into the fuel cell unit 200 when evaporated by heat exchange with the buffer boil-off gas, and is recovered to the storage tank 100 in the liquid state.

Since the liquefied natural gas is stored in the medium pressure tank 320, the evaporated gas is generated due to natural vaporization as in the storage tank 100. The boil-off gas generated in the medium pressure tank 320 is guided to the heat exchanger 350, is converted into a liquid through heat exchange with the cryogenic liquefied natural gas supplied from the storage tank 100, and then stored in the medium pressure tank 320 again. . The cryogenic liquefied natural gas may be vaporized by heat exchange with the boil-off gas. In this case, as illustrated in FIG. 2, the liquefied natural gas may be joined to the connection flow path F in the storage tank 100 through the flow path a1 and thus the fuel cell. The unit 200 is supplied with fuel. Even after heat exchange, when the liquefied natural gas is not vaporized and remains in a liquid state, the natural gas is stored in the storage tank 100 through the flow path a2.

The medium pressure buffer unit 300 is provided in the connection flow path F connecting the storage tank 100 and the fuel cell unit 200 to detect whether or not the evaporated gas generated in the storage tank 100 is supplied to the connection flow path. The sensor 360 may further include a controller (not shown) for opening and closing the valve 340 by a signal sensed by the sensor 360.

The sensor 360 detects whether fuel is supplied to the fuel cell unit 200 while measuring the flow rate of the boil-off gas in the connection flow path F, and when a supply stop is detected, the sensor 360 opens the valve 340 through a controller (not shown). The liquefied natural gas stored from the medium pressure tank is supplied to the fuel cell unit 200 via the vaporizer 330.

The valve 340 of the medium pressure buffer unit 300 is in a closed state when the boil-off gas is normally supplied to the fuel cell through the connection channel, so that the boil-off gas stored in the medium pressure tank 320 is not supplied to the fuel cell.

The fuel cell unit 200 includes a humidifier 210 for humidifying the boil-off gas supplied from the storage tank 100 or the medium pressure buffer unit 300, a reformer 220 for reforming the boil-off gas with hydrogen and carbon dioxide, and an anode. A fuel cell 230 that generates electricity by an electrochemical reaction of hydrogen and carbon dioxide supplied and oxygen supplied from a cathode, a blower 240 that supplies external air to the fuel cell 230, and a blower 240. It includes an air heater 250 for heating the air supplied to the fuel cell through.

The humidifier 210 serves to humidify and supply a gas (hydrogen or oxygen) supplied as fuel to the fuel cell 230 so that the fuel cell 230 exhibits optimal performance.

The gas is used as fuel for the fuel cell 230 after passing through the humidifier 210 and the reformer 220.

The reformer 220 serves to reform the evaporation gas into hydrogen and carbon dioxide. Specifically, the boil-off gas is mixed with the supplied water (pure water) and the humidifier 210 and phase-converted to the moist fuel.

The wet fuels are then reformed and high hydrocarbons, excluding methane, are removed. The methane gas reformed fuel gas is reformed into carbon dioxide and hydrogen by the supplied heat.

The fuel cell 230 of the fuel cell unit 200 is supplied with the reformed hydrogen and carbon dioxide from the cathode side through the air blower 240 and the air heater 250, And to generate electricity by causing an electrochemical reaction with the oxidizing gas.

That is, the anode side of the fuel cell is supplied with the fuel gas containing at least hydrogen, and the cathode side of the fuel cell 230 is supplied with the oxidizing gas containing at least oxygen. Electricity is obtained by a redox reaction of a fuel gas containing hydrogen and an oxidizing gas containing oxygen.

Hereinafter, a state of use of the fuel cell system of the fuel cell equipped ship according to the present embodiment will be briefly described with reference to FIG. 2.

First, a state in which the evaporative gas is normally supplied to the fuel cell 230 will be described. The boil-off gas generated in the storage tank 100 is supplied to the humidifier 210 through the connection flow path (F). At the same time, a portion of the liquefied natural gas in the storage tank 100 is stored in the medium pressure tank 320 at a medium pressure of about 5 bar through the pump 310, and the liquefied natural gas stored in the medium pressure tank 320 is closed the valve 340. ) Is not supplied to the fuel cell unit 200. The evaporated gas generated from the liquefied natural gas stored in the medium pressure tank 320 is liquefied and stored again in the heat exchanger 350, and the liquefied natural gas used for the heat exchange received from the storage tank 100 is vaporized when the fuel cell unit ( 200).

On the other hand, the evaporated gas supplied to the humidifier 210 is mixed with the liquid vaporized in the humidifier 210 to become a wet evaporated gas. The moist evaporative gas is supplied to the reformer 220 and reformed into hydrogen and carbon dioxide in the reformer 220, and the reformed hydrogen and carbon dioxide are supplied to the fuel cell 230.

The anode of the fuel cell 230 receives hydrogen and carbon dioxide and operates with an oxidizing gas containing oxygen supplied to the cathode through the blower 240 and the air heater 250 to generate electricity by an electrochemical reaction.

On the other hand, when the supply of the boil-off gas through the connection flow path (F), the sensor 360 recognizes this and sends a signal to the controller (not shown). The controller opens the valve 340 in the buffer connection flow path B based on the above-described signal so that the liquefied natural gas stored in the medium pressure tank 320 is supplied to the humidifier 210 through the vaporizer 330. The evaporated gas supplied to the humidifier 210 is used as fuel for the fuel cell 230 after passing through the humidifier 210 and the reformer 220 as described above.

According to another aspect of the present invention, a fuel supply method of a fuel cell-equipped vessel is provided in a hull and in a fuel supply method of a fuel cell for ships using a boil-off gas supplied from a storage tank 100 in which liquefied natural gas is stored, the storage tank After storing a part of the liquefied natural gas stored in the medium pressure state, when the supply of the boil-off gas supplied to the fuel cell is stopped by vaporizing the stored medium pressure liquefied natural gas, it is characterized in that the fuel cell is operated without stop. do.

As described above, the present embodiment can continuously operate without stopping the fuel cell by the buffer gas unit even when the supply of the fuel supplied to the fuel cell is stopped, thereby improving the availability of the fuel cell. Since liquid liquefied natural gas is stored as a medium pressure liquid, it can occupy less volume and increase space efficiency, and it is relatively free to be placed on board because it does not comply with high pressure regulations of the ship.

In addition, it is possible to reduce the cost of installing additional equipment such as a high pressure compressor, a high pressure tank, and safety related facilities required for high pressure gas storage, and to reduce the risk of explosion due to high pressure gas storage, thus enabling a safe LNG ship fuel cell system. .

It will be apparent to those skilled in the art that various modifications and variations can be made in the present invention without departing from the spirit or scope of the invention. Accordingly, such modifications or variations are intended to fall within the scope of the appended claims.

H: Hull
F: connecting flow path
B: Buffer Connection Channel
100: storage tank
200: fuel cell unit
210: Humidifier
220: reformer
230: Fuel cell
240: blower
250: Air heater
300: medium pressure buffer unit
310: pump
320: medium pressure tank
330: carburetor
340: valve
350: heat exchanger
360: sensor

Claims (7)

As electric power operation system of LNG carrier,
A storage tank provided in the hull and storing liquefied natural gas (LNG) therein;
A fuel cell unit provided in the hull and using a boil-off gas generated in the storage tank as a fuel; And
And a medium pressure buffer unit configured to store the liquefied natural gas supplied from the storage tank in a medium pressure state, and supply the liquefied natural gas stored at the supply of the fuel supplied to the fuel cell unit to the fuel cell unit.
The medium pressure buffer unit may include: a pump provided in the hull and pumping the liquefied natural gas supplied from the storage tank to transfer the medium to a medium pressure state; A medium pressure tank storing the medium pressure liquefied natural gas transferred from the pump; And a heat exchanger for liquefying the buffer boil-off gas generated in the medium pressure tank by heat exchange with the liquefied natural gas supplied from the storage tank. The apparatus of claim 1, wherein the intermediate pressure buffer unit
A vaporizer for vaporizing the medium pressure liquefied natural gas stored in the medium pressure tank; And
And a valve provided in a buffer connection flow path connecting the vaporizer and the fuel cell unit to open and close the buffer connection flow path. delete 3. The method of claim 2,
The liquefied natural gas passing through the heat exchanger is introduced into the fuel cell unit when evaporated by heat exchange with the buffer boil-off gas, and is recovered to the storage tank in a liquid state. . The method of claim 2, wherein the medium pressure buffer unit,
A sensor provided in a connection flow path connecting the storage tank and the fuel cell unit to detect whether boil-off gas generated in the storage tank is supplied to the connection flow path; And
And a control unit for opening and closing the valve by a signal sensed by the sensor. The fuel cell system according to claim 1, wherein the fuel cell unit
A humidifier for humidifying the boil-off gas supplied from the storage tank or the medium pressure buffer unit;
A reformer for reforming the evaporated gas into hydrogen and carbon dioxide;
A fuel cell generating electricity by an electrochemical reaction of the hydrogen supplied to the anode and the oxygen supplied from the carbon dioxide and the cathode;
A blower for supplying external air to the fuel cell; And
And a fuel heater for heating the air supplied to the fuel cell through the blower. In the fuel supply method of the ship fuel cell using the boil-off gas provided in the hull and supplied from the storage tank in which the liquefied natural gas is stored,
A portion of the liquefied natural gas stored in the storage tank is stored at a medium pressure state, and when the supply of the boil-off gas supplied to the fuel cell is stopped, the medium-pressure liquefied natural gas stored in the storage tank is vaporized and supplied to the fuel cell to stop the fuel cell. Without operation,
And a buffer boil-off gas generated from the medium pressure liquefied natural gas is liquefied by heat exchange with the liquefied natural gas supplied from the storage tank.

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