KR102045956B1 - Combined power generation system using boil off gas - Google Patents

Abstract

The present invention relates to a combined power generation system using evaporative gas generated from liquefied natural gas. By driving a fuel cell system using evaporative gas generated from liquefied natural gas, dumped evaporative gas can be used for producing electricity. In addition, by coupling a carbon dioxide utilization system to remove carbon dioxide which is green-house gas emitted from the fuel cell system or other devices, and producing hydrogen which is a clean energy source to supply the same to a fuel cell, an environment-friendly combined power generation system without generation of carbon dioxide can be realized.

Description

COMBINED POWER GENERATION SYSTEM USING BOIL OFF GAS}

The present invention relates to a complex power generation system using the boil-off gas generated from liquefied natural gas.

Generally, liquefied natural gas (Liquefied Natural Gas, LNG) stores natural gas in a liquefied state due to the storage density of natural gas. Since natural gas is stored in the LNG storage tank at a very low temperature of minus 163 ° C, the gas always evaporates in the LNG storage tank. This evaporating gas is called a boil off gas (BOG). The LNG storage tank is wrapped with a heat insulating material to block external heat, but since it is technically difficult to block heat at 100%, a considerable amount of natural gas is vaporized. In order to prevent the LNG storage tank from exploding, the BOG is drawn out to the compressor, reliquefied, and sent back to the storage tank, or when the amount of BOG is large, the BOG is discharged to the outside of the storage tank by using a pressure control valve. LNG carriers use vaporized BOG as fuel, reliquefaction, or incineration, all of which are not very efficient or economical.

Meanwhile, with the recent industrialization, greenhouse gas emissions have been continuously increasing, and carbon dioxide accounts for the largest portion of greenhouse gases. Carbon dioxide emissions by industry type are the highest in energy sources such as power plants, and carbon dioxide from cement, steel, and refining industries, including power generation, accounts for half of the world's production. Increasing interest in preventing environmental pollution has led to tightening regulations on pollutant emission sources.

Accordingly, there is a need to develop a technology capable of efficiently using resources using BOG generated in LNG storage facilities or LNG transport vessels and reducing carbon dioxide, which is a greenhouse gas emitted at the same time.

As a prior patent document related to the technical field of the present invention, Korean Patent Publication No. 10-1911119 discloses a fuel cell hybrid hybrid system using BOG.

Republic of Korea Patent Publication No. 10-1911119 "Fuel cell hybrid hybrid system" (2016.06.07.)

An object of the present invention is to produce a hydrogen using a fuel cell system and carbon dioxide using a boil off gas (BOG) generated from liquefied natural gas (Liquefied Natural Gas, LNG) to the fuel cell system It is to provide a combined power generation system using boil-off gas that combines the supplying carbon dioxide utilization system.

In order to achieve the above object of the present invention, according to an aspect of the present invention, the storage unit for storing the liquefied natural gas (LNG), the boil-off gas generated from the liquefied natural gas (LNG) stored in the storage unit (BOG) Provided is a complex power generation system using an evaporation gas, including a fuel cell system for producing electricity using the carbon dioxide, and a carbon dioxide utilization system for producing hydrogen using carbon dioxide and supplying the produced hydrogen to the fuel cell system.

According to the present invention, all the objects of the present invention described above can be achieved. Specifically, by driving the fuel cell system using the boil-off gas generated from the liquefied natural gas, the boil-off gas can be used to generate electricity.

In addition, by combining the carbon dioxide utilization system to remove the carbon dioxide, a greenhouse gas emitted from the fuel cell system or other devices, to produce hydrogen as a clean energy source and supply it to the fuel cell, it is possible to implement an eco-friendly complex power generation system without carbon dioxide generation. .

1 is a schematic block diagram of a combined cycle power generation system using the boil-off gas according to the present invention.
2 is a schematic block diagram of a combined cycle power generation system using the boil-off gas according to an embodiment of the present invention.
Figure 3 is a schematic diagram showing the operation of the carbon dioxide utilization system according to an embodiment of the present invention.
Figure 4 is a schematic diagram showing the operation of the carbon dioxide utilization system according to another embodiment of the present invention.
5 is a schematic block diagram of a combined cycle power generation system using the boil-off gas according to another embodiment of the present invention.
Figure 6 is a schematic diagram showing the operation of the carbon dioxide utilization system according to another embodiment of the present invention.

Hereinafter, with reference to the drawings will be described in detail the configuration and operation of the embodiment of the present invention.

1 is a schematic block diagram of a combined power generation system 10 using a boil off gas (BOG) according to an embodiment of the present invention. Referring to FIG. 1, the combined power generation system 10 using the boil-off gas may be generated from a storage unit 100 for storing liquefied natural gas (Liquefied Natural Gas, LNG), and liquefied natural gas stored in the storage unit 100. It includes a fuel cell system 200 for producing electricity by using the evaporated gas and a carbon dioxide utilization system 300 for producing hydrogen by using the carbon dioxide generated from the fuel cell system 200.

The combined cycle power generation system 10 using the boil-off gas according to an embodiment of the present invention uses the boil-off gas generated in the storage unit 100 storing the liquefied natural gas as fuel of the fuel cell system 200. By generating and injecting carbon dioxide generated during operation of the fuel cell system 200 into the carbon dioxide utilization system 300 to produce hydrogen through a redox reaction, and supplying the produced hydrogen to the fuel of the fuel cell system 200 To improve the efficiency of resource use and to reduce carbon dioxide, a greenhouse gas.

The storage unit 100 stores the natural gas in a liquefied state to increase the storage capacity of the natural gas. The liquefied natural gas stored in the storage unit 100 may have a temperature of minus 163 ° C. The reservoir is designed and constructed using a material that can withstand cryogenic temperatures. Evaporated gas is generated from the liquefied natural gas, and the evaporated gas is generated by heat input through the storage unit 100 or a pipe or is generated by convection due to liquid stratification. The complex power generation system 10 using the boil-off gas according to the present invention may be implemented to supply the boil-off gas generated from the liquefied natural gas to the fuel cell system 200 without discharging to the outside or burning directly.

The fuel cell system 200 may generate electricity through an electrochemical reaction generated by fuel, electrolyte, and air, and the fuel includes the evaporated gas and / or hydrogen. The fuel cell system 200 may be directly connected to the storage unit 100 and the fuel cell system 200 to directly receive the boil-off gas generated from the storage unit 100. The boil-off gas generated in the storage unit 100 may be moved to the fuel cell system 200 through an air blower, an impeller, or a transfer pump. Alternatively, the evaporation gas may be supplied by separately connecting the evaporation gas storage space for storing the evaporation gas generated from the storage unit 100 to be connected thereto.

The fuel cell system 200 generates electricity using the evaporated gas generated from the liquefied natural gas stored in the storage unit 100. The fuel cell system 200 includes a fuel cell 210.

In one specific embodiment, the fuel cell 210 used in the fuel cell system includes a molten carbonate fuel cell (MCFC), a polymer electrolyte fuel cell (PEMFC), a solid oxide fuel cell (SOFC), and a phosphoric acid fuel cell (PAFC). ) And direct carbon fuel cell (DCFC), but is not limited thereto.

The fuel cell system 200 may further include a reformer 220. The reformer 220 produces reformed gas rich in hydrogen from the hydrogen containing fuel and additionally generates carbon dioxide gas. The reformed gas produced in the reformer is supplied to the fuel cell, and the carbon dioxide gas additionally generated in the reformer 220 is supplied to the carbon dioxide utilization system 300. To this end, in the present embodiment it will be described that the reformer 220 is a methane-steam reformer that produces hydrogen (H ₂ ) by the reforming reaction of methane (CH ₄ ) and water vapor (H ₂ O), the main components of the evaporation gas. .

The following [Scheme 1] relates to the reforming reaction of the methane-steam reformer.

Scheme 1

CH ₄ + H ₂ O-> CO + 3H ₂

CO + H ₂ O-> CO ₂ + H ₂

That is, carbon monoxide (CO) and hydrogen are produced by the chemical reaction of methane and water vapor, and hydrogen can be finally produced by the chemical reaction of carbon monoxide and water vapor.

The carbon dioxide utilization system 300 utilizes carbon dioxide generated from the fuel cell 210 or the reformer 220 of the fuel cell system 200 to produce hydrogen. The produced hydrogen may be supplied to the fuel cell system 200 to be used as fuel of the fuel cell system 200.

2 is a schematic block diagram of a combined power generation system 10a, 10b using boil-off gas according to another embodiment of the present invention. Referring to FIG. 2, the combined power generation systems 10a and 10b using the boil-off gas include a liquefied natural gas reservoir 100, a fuel cell system 200, and a carbon dioxide utilization system 300a and 300b. The combined power generation systems 10a and 10b supply the evaporated gas generated in the liquefied natural gas reservoir to the fuel cell system 200, and the fuel cell system generates electricity and generates carbon dioxide. The carbon dioxide generated in the fuel cell system 200 is supplied to the carbon dioxide utilization systems 300a and 300b and the carbon dioxide utilization systems 300a and 300b produce hydrogen and electricity through voluntary electrochemical reactions. Hydrogen produced by the carbon dioxide utilization systems 300a and 300b may be used as a fuel of the fuel cell system 200.

3 illustrates a configuration of a carbon dioxide utilization system 300a according to a specific embodiment of the present invention. Referring to FIG. 3, the carbon dioxide utilization system 300a includes a first accommodating space 311, a first aqueous solution 312, and a cathode 313 at least partially submerged in the first aqueous solution 312. An anode portion including a cathode portion 310, a second accommodating space 321, a basic second aqueous solution 322 and a metal anode 323 at least partially submerged in the second aqueous solution 322. And a connection part 330 connecting the cathode part 310 and the anode part 320.

The carbon dioxide utilization system 300a may collect carbon dioxide introduced into the first aqueous solution 312 into bicarbonate ions, generate hydrogen ions, and react with the electrons of the hydrogen ions and the cathode 313 to produce hydrogen. . That is, through the spontaneous redox reaction process using carbon dioxide gas (CO ₂ ), which is a greenhouse gas, as a raw material, hydrogen (H ₂ ), which is an environmentally friendly fuel, is produced.

The cathode unit 320 includes a first aqueous solution 312 contained in the first accommodating space 311 and a cathode 313 at least partially submerged in the first aqueous solution 312. As the first aqueous solution 312, an alkaline aqueous solution (in this embodiment, eluted with CO ₂ in a strongly basic solution of 1M KOH), seawater, tap water, and distilled water may be used. The cathode 313 is an electrode for forming an electric circuit, and may be carbon paper, carbon fiber, carbon felt, carbon cloth, metal foam, metal thin film, or a combination thereof, and a platinum catalyst may also be used. In the case of a catalyst, in addition to the platinum catalyst, all other catalysts that can be generally used as an oxygen generation reaction (HER) catalyst, such as a carbon-based catalyst, a carbon-metal based composite catalyst, and a perovskite oxide catalyst, are also included.

The cathode 320 may have a first inlet and a first outlet communicating with the first receiving space 311. The first inlet may be located below the first receiving space 311 to be located below the surface of the first aqueous solution 312. The first outlet may be positioned above the first receiving space 311 to be positioned above the water surface of the first aqueous solution 312. Carbon dioxide used as fuel in the reaction process is introduced into the first accommodation space 311 through the first inlet, and the gas generated in the required reaction process may be discharged to the outside. Although not shown, the inlet and outlet may be selectively opened and closed at an appropriate time by a valve or the like during filling and reaction. In the cathode 320, a carbon dioxide eluting reaction occurs during the reaction.

The anode part 320 includes a second aqueous solution 322 contained in the second receiving space 321 and an anode 323 at least partially submerged in the second aqueous solution 322. As the second aqueous solution 322, a high concentration of an alkaline solution is used. For example, 1M KOH or 6M KOH may be used. The anode 323 is a metal electrode constituting an electric circuit, and in this embodiment, zinc (Zn) or aluminum (Al) is used as the anode 323. In addition, an alloy including zinc or aluminum may be used as the anode 323.

Now, the reaction process of the carbon dioxide utilization system 100a described above as the configuration center is described in detail. Carbon dioxide is injected into the first aqueous solution 312 through the inlet, and the cathode 320 performs a chemical elution reaction of carbon dioxide as shown in the following [Scheme 2].

Scheme 2

_{H 2 O (l) + CO} 2 (g) → H + (aq) + HCO 3 - (aq)

That is, in the cathode unit 320, the carbon dioxide (CO ₂ ) supplied to the cathode unit 320 undergoes a spontaneous chemical reaction with water (H ₂ O) of the first aqueous solution 312 to form a hydrogen cation (H ⁺ ) and a bicarbonate ( HCO ₃ ⁻ ) is produced.

In addition, the cathode 320 is made an electrical reaction as shown in the following [Scheme 3].

Scheme 3

^{2H + (aq) + 2e -} → H 2 (g)

That is, the hydrogen cation (H ⁺ ) in the cathode 320 receives electrons (e ⁻ ) to generate hydrogen (H ₂ ) gas. The generated hydrogen (H ₂ ) gas is discharged to the outside through the first outlet.

In addition, the cathode 320 is a complex hydrogen generation reaction as shown in the following [Reaction Scheme 4].

Scheme 4

_{2H 2 O (l) + 2CO} 2 (g) + 2e - → H 2 (g) + 2HCO 3 - (aq)

In the anode 320, when the anode 323 is zinc (Zn), an oxidation reaction is performed as shown in [Scheme 5].

Scheme 5

^{Zn + 4OH - → Zn (OH} ) 4 2- + 2e - (E 0 = -1.25V)

^{_{Zn (OH) 4 2- → ZnO}} + H2O + 2OH -

As a result, when the anode 323 is zinc (Zn), the entire reaction formula performed in the reaction process is as follows.

Scheme 6

_{Zn + 2CO 2 + 2H 2 O} + 2OH - → ZnO + 2HCO 3 - (aq) + H 2 (g) (E 0 = 1.25V)

If the anode 323 is aluminum (Al) in the anode portion 320, an oxidation reaction is performed as shown in [Scheme 7].

Scheme 7

^{Al + 3OH - → Al (OH} ) 3 + 3e - (E 0 = -2.31V)

As a result, when the anode 323 is aluminum (Al), the entire reaction formula formed in the reaction process is as follows.

Scheme 8

_{2Al + 6CO 2 + 6H 2 O} + 6OH - → 2Al (OH) 3 + 6HCO 3 - (aq) + 3H 2 (g) (E 0 = 2.31V)

As a result, as can be seen from [Scheme 6] and [Scheme 8], the hydrogen ions generated by the carbon dioxide eluted in the first aqueous solution 312 during the reaction receives electrons from the cathode 313 to the hydrogen gas Is reduced, discharged through the first outlet, and the metal anode 323 is changed into the form of an oxide. As the reaction proceeds, HCO ₃ ⁻ (bicarbonate ion) is generated in the first aqueous solution 312.

As shown in FIG. 3, the connection part 330 blocks the movement of the first aqueous solution 312 and the second aqueous solution 322 and transfers ions of a porous structure through which ionic materials dissolved in the aqueous solution may pass. Member may be provided.

In one specific embodiment, the ion transport member may be a porous ion transport member. The porous ion transport member is generally in the shape of a disk and is installed in such a way as to block the inside of the connection passage 191. The porous ion transport member has a porous structure to allow movement of ions between the cathode portion 320 and the anode portion 320, while blocking the movement of the aqueous solutions 312 and 322. In this embodiment, the material of the ion transfer member is described as glass, but the present invention is not limited thereto, and other materials having a porous structure may also be used, which is also within the scope of the present invention. In this embodiment, the porous ion transport member has a pore size of 40 to 90 microns corresponding to G2 grade, 15 to 40 microns corresponding to G3 grade, 5 to 15 microns corresponding to G4 grade, and G5 grade Corresponding glass of 1 to 2 microns can be used. The ion transfer member 192 transfers only ions to solve the ion imbalance generated in the reaction process.

4 shows a configuration of a carbon dioxide utilization system 300b according to another specific embodiment of the present invention. Referring to FIG. 4, the carbon dioxide utilization system 300b includes a reaction space 341, an aqueous solution 342 accommodated in the reaction space, a cathode 313 at least partially submerged in the aqueous solution 342, and the reaction space ( In 341, at least a portion of the aqueous solution 342 is immersed in a metal anode 323.

The reaction space 341 contains an aqueous solution 342 and houses a cathode 313 and an anode 323. The first inlet and the first outlet may be formed in the reaction space 341. The first inlet is located below the reaction space 341 so as to be below the water surface of the aqueous solution. The first outlet is located above the reaction space 341 so as to be above the water surface of the aqueous solution 342. Carbon dioxide, which is used as fuel in the reaction process, is introduced into the reaction space 341 through the first inlet, and an aqueous solution 342 may also be introduced if necessary. The gas generated in the reaction process is discharged to the outside through the first outlet. Although not shown, the first inlet and the first outlet may be selectively opened and closed at an appropriate time by a valve or the like during filling and reaction. In the reaction space 341, a carbon dioxide eluting reaction occurs during the reaction.

The aqueous solution 342 is contained in the reaction space 341, and at least a portion of the cathode 313 and at least a portion of the anode 323 are immersed in the aqueous solution 342. It will be described that a basic solution or seawater is used as the aqueous solution 342 in this embodiment. The aqueous solution 342 becomes weakly acidic by the carbon dioxide introduced through the first inlet during the reaction.

The cathode 313 is at least partially submerged in the aqueous solution 342 in the reaction space 341. Cathode 313 is located relatively closer to the first inlet than anode 323 in reaction space 341. The cathode 313 is an electrode for forming an electric circuit, and may be carbon paper, carbon fiber, carbon felt, carbon cloth, metal foam, metal thin film, or a combination thereof, and a platinum catalyst may also be used. In the case of the catalyst, in addition to the platinum catalyst, carbon-based catalysts, carbon-metal-based composite catalysts, perovskite oxide catalysts, and all other catalysts that can generally be used as an oxygen evolution reaction (HER) catalyst. During the reaction, a reduction reaction occurs in the cathode 313, thereby generating hydrogen.

The anode 323 is at least partially submerged in the aqueous solution 342 in the reaction space 341. The anode 323 is located relatively far from the first inlet in the reaction space 341 than the cathode 313. The anode 323 is a metal electrode constituting an electric circuit. In this embodiment, the anode 323 is vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), or nickel. It is explained that (Ni), copper (Cu), aluminum (Al) or zinc (Zn) are used. In the reaction, the anode 323 generates an oxidation reaction according to a weakly acidic environment.

Now, the reaction process of the carbon dioxide utilization system 100c described above as the configuration center is described in detail. 3 illustrates a reaction process of the carbon dioxide utilization system 100c. Referring to FIG. 3, carbon dioxide gas is injected into the aqueous solution 342 through the first inlet, and a chemical elution reaction of carbon dioxide is performed in the reaction space 341 as shown in [Scheme 2].

Scheme 2

_{H 2 O (l) + CO} 2 (g) → H + (aq) + HCO 3 - (aq)

That is, hydrogen cation (H ⁺ ) and bicarbonate (HCO ₃ ⁻ ) are produced through spontaneous chemical reaction of carbon dioxide (CO ₂ ) supplied to the reaction space 341 with water (H ₂ O) of the aqueous solution 342.

In addition, the cathode 313 performs an electrical reaction as shown in [Scheme 3].

Scheme 3

^{2H + (aq) + 2e -} → H 2 (g)

That is, the hydrogen cation (H ⁺ ) around the cathode 313 receives electrons (e ⁻ ) to generate hydrogen (H ₂ ) gas. The generated hydrogen (H ₂ ) gas is discharged to the outside through the first outlet.

In addition, a complex hydrogen generation reaction is performed around the cathode 313 as shown in the following [Scheme 4].

Scheme 4

_{2H 2 O (l) + 2CO} 2 (g) + 2e - → H 2 (g) + 2HCO 3 - (aq)

When the anode 323 is zinc (Zn), an oxidation reaction is performed as shown in [Scheme 5].

Scheme 5

^{Zn + 4OH - → Zn (OH} ) 4 2- + 2e - (E 0 = -1.25V)

^{_{Zn (OH) 4 2- → ZnO}} + H 2 O + 2OH -

As a result, when the anode 323 is zinc (Zn), the entire reaction formula performed in the reaction process is as follows.

Scheme 6

_{Zn + 2CO 2 + 2H 2 O} + 2OH - → ZnO + 2HCO 3 - (aq) + H 2 (g) (E 0 = 1.25V)

If the anode 323 is aluminum (Al), an oxidation reaction is performed as shown in [Scheme 7].

Scheme 7

^{Al + 3OH - → Al (OH} ) 3 + 3e - (E 0 = -2.31V)

As a result, when the anode 323 is aluminum (Al), the entire reaction formula formed in the reaction process is as follows.

Scheme 8

_{2Al + 6CO 2 + 6H 2 O} + 6OH - → 2Al (OH) 3 + 6HCO 3 - (aq) + 3H 2 (g) (E 0 = 2.31V)

As a result, as can be seen from [Scheme 6] and [Scheme 8], the hydrogen ions generated by the carbon dioxide eluted in the aqueous solution 342 during the reaction receives electrons from the cathode 313 is reduced to hydrogen gas And is discharged through the first outlet, and the metal anode 323 is changed into an oxide. As the reaction proceeds, HCO ₃ ⁻ (bicarbonate ion) is generated in the aqueous solution 342.

5 is a schematic block diagram of a combined cycle power generation system 10c using boil-off gas according to another embodiment of the present invention. Referring to FIG. 5, the complex power generation system 10c using the boil-off gas includes a liquefied natural gas reservoir 100, a fuel cell system 200, and a carbon dioxide utilization system 300c. The complex power generation system 10c supplies the evaporated gas generated in the liquefied natural gas reservoir to the fuel cell system 200, and the fuel cell system generates electricity and generates carbon dioxide. The carbon dioxide generated in the fuel cell system 200 is supplied to the carbon dioxide utilization system 300c and the carbon dioxide utilization system 300c receives power from the power source 400 to produce hydrogen, chlorine and electricity through an electrochemical reaction. do. Hydrogen produced by the carbon dioxide utilization system 300c may be used as a fuel of the fuel cell system 200.

6 schematically illustrates a configuration of a carbon dioxide utilization system 300c according to another specific embodiment of the present invention. Referring to FIG. 6, the carbon dioxide utilization system 300a includes a reaction space 341, an electrolyte solution 343 accommodated in the reaction space 341 and including a chlorine anion, and the electrolyte solution solution in the reaction space 341. A cathode 313 at least partially submerged in 343, a hydrogen discharge part for discharging hydrogen generated from the cathode 313, and an anode 323 at least partially submerged in the electrolyte aqueous solution 343 in the reaction space 341. And a power source 400 electrically connected to the cathode 313 and the anode 323. The carbon dioxide utilization system 100c may generate hydrogen and chlorine by using carbon dioxide as a raw material using electrical energy supplied from the power source 400.

In the reaction space 341, a carbon dioxide elution reaction occurs.

The aqueous electrolyte solution 343 is contained in the reaction space 341, and at least a portion of the cathode 313 and at least a portion of the anode 323 are immersed in the aqueous electrolyte solution 343. The aqueous electrolyte solution 343 is an aqueous electrolyte solution containing chlorine ions (Cl ⁻ ), such as seawater or brine, and is described as an aqueous sodium chloride (NaCl) solution in this embodiment. The resulting aqueous electrolyte solution 343 includes sodium cation (Na ⁺ ) and chlorine anion (Cl ⁻ ).

The cathode 313 is at least partially submerged in the aqueous electrolyte solution 343 in the reaction space 341. The cathode 313 is electrically connected to the cathode of the power source 400 to receive electrons from the power source 400. The cathode 313 may be carbon paper, carbon fiber, carbon felt, carbon cloth, metal foam, metal thin film, or a combination thereof, and a platinum catalyst may also be used. In the case of the catalyst, in addition to the platinum catalyst, carbon-based catalysts, carbon-metal-based composite catalysts, perovskite oxide catalysts, and other catalysts that can generally be used as hydrogen evolution catalysts are also included. In the cathode 313, a hydrogen evolution reaction (HER) occurs by a reduction reaction.

The hydrogen discharge part is preferably positioned above the cathode 312 of the reaction space so as to be located above the water surface of the electrolyte solution 343. Hydrogen generated in the carbon dioxide utilization system 100 is discharged through the hydrogen outlet.

The anode 323 is at least partially submerged in the aqueous electrolyte solution 343 in the reaction space 341. The anode 323 is electrically connected to the anode of the power source 400 to supply electrons to the power source 400. In this embodiment, the anode 323 is vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), aluminum (Al) or zinc It is explained that (Zn) is used. In addition, the anode 323 may be carbon paper, carbon fiber, carbon felt, carbon cloth, metal foam, metal thin film, or a combination thereof, and a platinum catalyst may also be used. In the case of the catalyst, in addition to the platinum catalyst, carbon-based catalysts, carbon-metal-based composite catalysts, perovskite oxide catalysts, and other catalysts that can generally be used as combustion generating catalysts are also included. In the anode 323, a chlorine evolution reaction (CER) occurs by an oxidation reaction.

The chlorine discharge unit may discharge chlorine (Cl ₂ ) or chlorine-based compound (HClO, etc.) generated from the anode 323 to the outside of the carbon dioxide utilization system 300c. When the combined power generation system 10c using the boil-off gas according to the present embodiment is installed in a vessel, the generated chlorine or chlorine compound is stored in a separate storage facility or supplied to a ballast water treatment system to sterilize the ballast water of the vessel. It can be used to

An inlet through which carbon dioxide is supplied may be formed in the reaction space 341. The inlet is preferably located below the water surface of the aqueous electrolyte solution 343 of the reaction space 341. Carbon dioxide, a raw material, is introduced into the reaction space 341 through the inlet, and an aqueous electrolyte solution 343 may also be introduced if necessary.

Now, a process of generating hydrogen while carbon dioxide is removed from the carbon dioxide utilization system 300c will be described. As shown in FIG. 6, carbon dioxide gas is injected into the electrolyte solution 343, which is an aqueous sodium chloride solution, through the inlet, and a chemical elution reaction of carbon dioxide is performed in the reaction space 341 as shown in the following [Scheme 2].

Scheme 2

_{H 2 O (l) + CO} 2 (g) → H + (aq) + HCO 3 - (aq)

That is, the carbon dioxide (CO ₂ ) supplied to the reaction space 341 is hydrogen cation (H ⁺ ) and bicarbonate (HCO ₃ ⁻ ) through spontaneous chemical reaction with water (H ₂ O), which is a solvent of the aqueous electrolyte solution 343. Is generated. The reaction of [Scheme 2] acidifies the electrolyte solution.

In addition, the cathode 313 performs an electrical reaction as shown in [Scheme 3].

Scheme 3

^{2H + (aq) + 2e -} → H 2 (g)

That is, hydrogen cations (H ⁺ ) around the cathode 313 receives electrons (e ⁻ ) from the cathode 313 to generate hydrogen (H ₂ ) gas. The hydrogen evolution reaction occurring at the cathode 313 makes the electrolyte solution 343 basic. The generated hydrogen (H ₂ ) gas may be discharged to the outside through the hydrogen discharge unit 140.

In addition, in the vicinity of the cathode 313, a complex hydrogen generation reaction is performed as shown in [Scheme 4].

Scheme 4

_{2H 2 O (l) + 2CO} 2 (g) + 2e - → H 2 (g) + 2HCO 3 - (aq)

In addition, the anode 323 generates a chlorine generation reaction as shown in the following [Formula 9].

Scheme 9

_{^{2Cl - (aq) → Cl 2}} (g) + 2e - (E 0 = 1.25V)

As a result, the final reaction scheme is shown in the following [Scheme 10] and [Scheme 11].

Scheme 10

_{2NaCl (aq) + 2H 2 O} (l) + 2CO 2 (g) → 2NaHCO 3 (aq) + 2H + (aq) + 2Cl - (aq)

Scheme 11

^{2H + (aq) + 2Cl -} (aq) → H 2 (g) + Cl 2 (g)

As can be seen from [Scheme 10] and [Scheme 11], since the hydrogen ions (H ⁺ ) disappear after the electrolytic reaction, the pH of the electrolyte solution (343) is increased and basicized, so that the carbon dioxide flowing through the inlet is Can continue to be dissolved. The aqueous electrolyte solution 343, which was initially an aqueous solution of sodium chloride (NaCl), gradually changes to an aqueous solution of sodium hydrogen carbonate (NaHCO ₃ ) as the reaction continues.

In the present embodiment, it was described that an aqueous sodium chloride (NaCl) solution is used as the electrolyte solution 343, but a solution containing another cation such as an aqueous potassium chloride (KCl) solution or calcium chloride (CaCl ₂ ) solution may be used instead of the aqueous sodium chloride solution. In this case, a corresponding carbonate may be produced.

The carbon dioxide utilization system 300c adjusts the amount of chlorine generated in the anode such that the amount of carbon dioxide dissolved in the electrolyte aqueous solution 343 is maintained above a set value, thereby setting the pH of the electrolyte aqueous solution 343. The above can be maintained.

On the other hand, chlorine ions in the electrolyte solution (343) (Cl ^-), when conducted using no solution in the anode 323 is made, and then the oxygen generating reaction as shown in [Scheme 12].

Scheme 12

^{_{4OH - → O 2 + 2H 2}} O + 4e -

Accordingly, the pH of the aqueous electrolyte solution 343 does not change, and carbon dioxide is not further dissolved.

A positive electrode of the power source 400 is electrically connected to the anode 323 and a negative electrode of the power source 400 is electrically connected to the cathode 130 to provide electrical energy to the carbon dioxide utilization system 300c. As the power source 400, any type of power source capable of providing electrical energy including renewable energy such as solar cells and wind power generation may be used, and may be supplied from the fuel cell system 200.

The complex power generation system 10 using the boil-off gas according to another embodiment of the present invention may be installed in a ship. When installing the combined power generation system 10 using the boil-off gas on the ship, the carbon dioxide utilization system 300 included in the combined power generation system 10 using the boil-off gas to produce hydrogen by utilizing the carbon dioxide generated from the ship's drive system. Can be. In this case, when utilizing the carbon dioxide generated from the driving device of the ship, it is possible to reduce or remove carbon dioxide, which is a greenhouse gas generated during the operation of the ship, and to produce hydrogen, which is an environmentally friendly fuel. On the other hand, the hydrogen produced as described above may be supplied to the driving device of the ship to improve the output of the driving device. Accordingly, it is possible to reduce the fuel required to propel the ship. Although not limited thereto, the driving device may be a dual fuel engine that uses at least one of diesel and natural gas as fuel.

Although the present invention has been described through the above embodiments, the present invention is not limited thereto. The above embodiments may be modified or changed without departing from the spirit and scope of the present invention, and those skilled in the art will recognize that such modifications and changes also belong to the present invention.

10, 10a, 10b, 10c: combined power generation system using boil-off gas
100: storage 200: fuel cell system
210: fuel cell 220: reformer
300, 300a, 300b, 300c: carbon dioxide utilization system
310: cathode part 311: first accommodation space
312 first aqueous solution 313 cathode
320: anode part 321: second accommodation space
322 second aqueous solution 323 anode
330: connection portion 341: reaction space
342: aqueous solution 343: electrolyte solution
400: power

Claims (10)

A storage unit for storing liquefied natural gas;
A fuel cell system for generating electricity using Boil Off Gas (BOG) generated from Liquefied Natural Gas (LNG) stored in the storage unit; And
Includes; carbon dioxide utilization system for producing hydrogen by using carbon dioxide generated in the fuel cell system,
The carbon dioxide utilization system,
A reaction solution, an aqueous electrolyte solution contained in the reaction space and containing a chlorine anion, a cathode at least partially submerged in the aqueous electrolyte solution in the reaction space, a hydrogen discharge part for discharging hydrogen generated from the cathode, and the electrolyte in the reaction space An anode submerged in an aqueous solution, a chlorine discharge portion for discharging chlorine generated from the anode, and a power source electrically connected to the cathode and the anode,
The carbon dioxide injected into the reaction space is introduced into the aqueous electrolyte solution of the reaction space, and hydrogen ions and bicarbonate ions are generated by the reaction of water of the aqueous electrolyte solution with the carbon dioxide.
Electric power is applied by the power source, and the hydrogen ions and the electrons of the cathode are combined to produce hydrogen at the cathode, and at the anode, electrons are separated from the chlorine anion to produce chlorine, thereby generating a combined power generation using an evaporation gas. system. The method of claim 1,
The fuel cell may be any one or more of a molten carbonate fuel cell (MCFC), a polymer electrolyte fuel cell (PEMFC), a solid oxide fuel cell (SOFC), a phosphoric acid fuel cell (PAFC) and a direct carbon fuel cell (DCFC). Composite power generation system using boil-off gas. The method of claim 1,
A composite power generation system using evaporative gas, characterized in that for supplying hydrogen produced by the carbon dioxide utilization system to the fuel cell system. delete delete delete The method of claim 1,
The anode is made of vanadium (V), chromium (Cr), manganese (Mn), iron (Fe), cobalt (Co), nickel (Ni), copper (Cu), aluminum (Al) or zinc (Zn). Power generation system using evaporative gas. The method of claim 1,
Combined power generation system using the boil-off gas is characterized in that for the ship, combined power generation system using the boil-off gas. The method of claim 8,
The carbon dioxide utilization system is characterized in that to utilize the carbon dioxide generated in the drive device of the vessel, a composite power generation system using evaporation gas. The method of claim 8,
The carbon dioxide utilization system is characterized in that for supplying the hydrogen produced by the driving device of the ship, a complex power generation system using evaporation gas.

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