KR20160128699A - Fuel cell power generating apparatus and method in offshore structure - Google Patents

Abstract

The present invention relates to a fuel cell power generating apparatus and a method in an offshore structure, wherein a hydrogen generation module generates hydrogen by passing through modified reaction from LNG stored in an LNG storage tank in an offshore structure, and a fuel cell module is supplied with hydrogen to generate power. Therefore, compared to a conventional land fixing type fuel cell power generating plant, construction costs can be reduced, and pollution of a forest and around facilities can be prevented. Moreover, the problem of environmental pollution with respect to exhaust gas emission can be solved.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a fuel cell power generation apparatus and method for an offshore structure,

The present invention relates to an apparatus and a method for generating a fuel cell in an offshore structure, and more particularly, a hydrogen production module in an offshore structure produces hydrogen from LNG stored in an LNG storage tank through a reforming reaction, The present invention relates to a fuel cell power generation apparatus and method for an offshore structure capable of generating electricity by supplying hydrogen produced.

Fuel cells are the most promising way to replace existing energy sources, and many studies on fuel cells are under way. In the field of power plants, there is a tendency to use fuel cells. A plant configured to generate electricity using a fuel cell is a plant for fuel cell power generation.

A fuel cell is a fuel for fuel cells (for example, a synthesis gas containing hydrogen or hydrogen) electrochemically reacting to obtain electricity.

The electricity generating principle of the fuel cell will be described as follows.

Hydrogen is decomposed into hydrogen ions and electrons in the fuel electrode. Hydrogen ions move to the air electrode through the electrolyte. The electrons generate electric current through the external circuit, and hydrogen ions, electrons and oxygen combine with each other in the air electrode. .

Generally, a plant for fuel cell power generation is constructed as a land fixed type. Such a land fixed type fuel cell power generation plant can not be moved, and a construction paper cost, a foundation cost, and a construction time are long. There is a problem that usage is limited only at a place.

In addition, when the local weather conditions and working conditions for constructing a plant for land fixed fuel cell power generation are inadequate, it is difficult to construct a plant for land fixed fuel cell power generation.

In addition, there is a problem in that it is difficult to obtain a workforce including a construction engineer in a field where a plant for land-based fixed fuel cell power generation is to be built.

In addition, the construction of land-based fixed-fuel cell power plants not only destroys forests, but also pollutes the environment. In addition, the pollution of the environment, such as carbon dioxide (CO ₂ ), which is the cause of global warming, There is a problem.

In order to solve the above-described problems, the present invention provides a hydrogen generating module for generating hydrogen from an LNG stored in an LNG storage tank in an offshore structure through a reforming reaction, Unlike a land stationary fuel cell power generation plant, it can be used as a fuel cell power generation device of an offshore structure capable of reducing the construction cost of foundation, preventing pollution around forests and facilities, The present invention has been made in view of the above problems.

To achieve the above object, the present invention provides a marine structure; An LNG storage tank provided in the offshore structure for storing LNG; A hydrogen production module provided in the offshore structure to produce hydrogen from the LNG stored in the LNG storage tank; A hydrogen storage tank provided in the offshore structure for storing hydrogen produced by the hydrogen production module; A fuel cell module provided in the offshore structure to generate electricity by receiving hydrogen stored in the hydrogen storage tank; A power converter for converting the direct current (DC) produced by the fuel cell module into an alternating current (AC); And an electric storage unit for storing the electricity generated by the fuel cell.

The LNG storage tank and the hydrogen storage tank may be installed in the offshore structure, and the hydrogen production module and / or the fuel cell module may be installed on the offshore structure.

According to another aspect of the present invention, there is provided a process for producing hydrogen, comprising: producing hydrogen from a hydrogen production module from LNG stored in an LNG storage tank; Storing the hydrogen produced by the hydrogen production module in a hydrogen storage tank; And generating power from the fuel cell module by receiving hydrogen stored in the hydrogen storage tank.

The hydrogen production process of the hydrogen production module may use at least one of a steam reforming reaction, a partial oxidation reaction, and an autothermal reaction.

The steam reforming equation is CH ₄ + H ₂ O + Heat = CO + 3H ₂ , And the partial oxidation reforming equation is CH ₄ + (1/2) O ₂ = CO + 2H ₂ And the autothermal reforming equation is CH ₄ + x O ₂ + (2-2x) H ₂ O = CO ₂ + (4-2x) H ₂ .

In the autothermal reforming reaction scheme, when methane is used as a reactant, the x value at which the total reaction heat (ΔH) becomes 0 is 0.44. When methane in the hydrocarbon is used as the reactant, the overall reaction formula is CH ₄ + 0.44 O ₂ + 1.12H ₂ O = CO ₂ + 3.12H ₂ .

As described above, according to the present invention, in the offshore structure, the hydrogen production module generates hydrogen from the LNG stored in the LNG storage tank through the reforming reaction, and the fuel cell module generates hydrogen by supplying hydrogen, Unlike a plant for fuel cell power generation, it can reduce the construction cost of foundation, prevent pollution of forests and surrounding facilities, and solve environmental pollution problem of exhaust gas emission.

1 is a schematic view showing a fuel cell power generation apparatus for an offshore structure according to a preferred embodiment of the present invention;
2 is a view for explaining a power generation process in a fuel cell power generation apparatus for an offshore structure according to a preferred embodiment of the present invention;
3 is a view showing a fuel cell power generation apparatus for an offshore structure according to a modification of the present invention.
4 is a flow chart showing a fuel cell power generation method for an offshore structure according to the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, an apparatus and method for generating a fuel cell in an offshore structure according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

FIG. 1 is a view illustrating a fuel cell power generation apparatus for an offshore structure according to a preferred embodiment of the present invention, and FIG. 2 is a view for explaining a power generation process in a fuel cell power generation apparatus for an offshore structure according to a preferred embodiment of the present invention .

The offshore structure of the present invention may be, for example, but not limited to, LNGC or FLNG, including all marine structures that produce, store, and transport LNG.

1 and 2, a fuel cell power generation apparatus 100 for an offshore structure of the present invention includes a hydrogen production module 120 for producing hydrogen from LNG of an LNG storage tank 110 installed in an offshore structure.

The hydrogen production module 120 is a reformer installed in the ocean. Unlike a reformer installed on the land, the hydrogen production module 120 can be miniaturized and compactly modularized so as to be mounted in an offshore structure.

The fuel cell power generation apparatus 100 of the present invention includes a hydrogen storage tank 130 installed in an offshore structure to store hydrogen produced by the hydrogen production module 120 in a liquefied state.

The fuel cell power generation apparatus 100 of the present invention includes a fuel cell module 140 that receives hydrogen stored in a hydrogen storage tank 130 to produce electric power.

The fuel cell power generation apparatus 100 of the present invention includes a power converter 150 for converting a direct current (DC) produced by the fuel cell module 140 into an alternating current (AC) And an electric storage unit 160.

3, the LNG storage tank 110 and the hydrogen storage tank 130 are installed inside an offshore structure, and the hydrogen production module 120 and / or the fuel cell module 140 are installed in the offshore structure, As shown in FIG.

Generally, there are two methods of supplying hydrogen used as a fuel cell fuel source. That is, pure hydrogen is produced and supplied through a reaction / purification process at a hydrogen plant, and a method for producing / supplying hydrogen directly by reforming a hydrocarbon.

The method of producing and supplying pure hydrogen is the best method for the fuel cell, but the cost of the device (reactor and purification / separation cost) for producing pure hydrogen is high, and there are many problems in storage, transportation and supply.

Therefore, much research has been focused on a method for producing hydrogen directly from hydrocarbons and using it as a raw material for a fuel cell. For example, the following references [Applied Catalysis A: General 241 (2003) 261-269, International Journal of Hydrogen Energy 26 (2001) 291-301 and USP 6,713,040) lt; RTI ID = 0.0 > hydrocarbons. < / RTI >

Hydrogen fuel processing of hydrocarbons is divided into reforming, water gas shift reaction (WGS), and CO clean-up process.

The reforming reaction process of the hydrogen production module 120 can be divided into steam reforming, partial oxidation and autothermal reforming depending on whether oxygen and water vapor are supplied or not. At least one of the above reforming reactions may be used.

Since the steam reforming reaction is a highly endothermic reaction, heat must be supplied from the outside, and the reaction rate is limited by the rate at which heat is supplied. In order to operate the reforming process, a separate combustion process or heater capable of supplying heat from the outside is required.

The partial oxidation reaction partially burns hydrocarbons with oxygen to generate heat, carbon monoxide and hydrogen, and is combined with a water gas shift reaction to complete the reaction.

Partial oxidation reactions were initially of interest because they were exothermic and therefore had a fast startup and fast response time. However, the hydrogen content in the reformate was low (about 50%), At present, the autothermal reforming reaction has become a major concern because of the disadvantage that the heat of the reformate of 1000 ° C can not be efficiently utilized and the overall thermal efficiency is lowered.

The autothermal reforming reaction is a combination of steam reforming reaction and partial oxidation reaction, in which hydrocarbons, water vapor and air are reacted together. The heat generated by the partial oxidation reaction provides the heat necessary for the steam reforming reaction of the hydrocarbons.

In this case, by regulating the oxygen content and the water vapor content, it is possible to adjust the reaction heat of the overall reaction to be zero, which is most suitable for energy efficiency. The autothermal reaction is a reaction in which steam reforming, which is an endothermic reaction, and partial oxidation reaction, which is an exothermic reaction, are conducted together to perform thermal neutralization. Much research has been conducted to develop a fuel cell having high efficiency and low emission of pollutants.

4 is a process diagram illustrating a method for generating a fuel cell of an offshore structure according to the present invention.

Referring to FIG. 4, a method for generating a fuel cell for an offshore structure according to the present invention includes the steps of: (S10) producing hydrogen from a hydrogen production module 120 from LNG stored in an LNG storage tank 110; Storing (S 20) the hydrogen produced by the hydrogen production module (120) in the hydrogen storage tank (130); And a step (S30) of receiving power from the hydrogen stored in the hydrogen storage tank 130 and producing power from the fuel cell module 140. [

At least one of steam reforming reaction, partial oxidation reaction, and autothermal reaction may be used for the hydrogen generation process of the hydrogen generation module 120 as described above.

In the hydrogen production process, the steam reforming reaction is a reaction in which hydrocarbons and water vapor react with each other to generate carbon monoxide and hydrogen as shown in the following equation (1), and is combined with the WGS reaction to produce the reaction shown in the following equation (1) as a whole.

In addition, the partial oxidation reaction partially burns the hydrocarbon with oxygen to generate heat, carbon monoxide and hydrogen, and is combined with the WGS reaction to produce the following reaction (2).

The autothermal reforming reaction is a combination of steam reforming reaction and partial oxidation reaction. Hydrocarbon, steam and air are reacted together as shown in the following equation (3).

The above steam reforming reaction formula: CH ₄ + H ₂ O + Heat = CO + 3H ₂ (One) ego,

Partial Oxidation Scheme: CH ₄ + (1/2) O ₂ = CO + 2H ₂ (2)

The autothermal reforming reaction scheme is: CH ₄ + x O ₂ + (2-2x) H ₂ O = CO ₂ + (4-2x) H ₂ (3).

In the autothermal reforming reaction scheme, when methane is used as a reactant, the x value at which the total reaction heat (ΔH) becomes 0 is 0.44. When methane in the hydrocarbon is used as the reactant, the overall reaction formula is CH ₄ + 0.44 O ₂ + 1.12H ₂ O = CO ₂ + 3.12H ₂ (4).

The present invention can maintain the advantage of the autothermal reforming reaction by replacing the air or oxygen used as the oxidizing agent with hydrogen peroxide in the autothermal reforming reaction while keeping the hydrogen content, which is an advantage of the steam reforming reaction, high.

The autothermal reforming reaction using hydrogen peroxide can be expressed as follows, for example, when methane is used as the reactant as follows.

CH ₄ + x H ₂ O ₂ + 2 (1-x) H ₂ O = CO ₂ + (4-x) H ₂ (5)

Here, the formula (5) is composed of the following unit reactions.

CH ₄ + 1 / 2O ₂ = CO + 2H ₂ (5-1)

H ₂ O ₂ = H ₂ O + 1 / 2O ₂ ? H = -98 kJ / mol (5-2)

CO + H ₂ O = CO ₂ + H ₂ (5-3)

CH ₄ + H ₂ O = CO + 3H ₂ (5-4)

In addition, the energy level of hydrogen peroxide is as high as in Equation (5-2), and it can also act as a replenishing heat of the autothermal reforming reaction, thereby enhancing the energy efficiency.

The value x of the reaction sequence ΔH = 0 in the equation (5) is 0.485. Therefore, the total reaction equation is as shown in the following equation (6).

CH ₄ + 0.485H ₂ O ₂ + 1.03H ₂ O = CO ₂ + 3.515H ₂ (6)

Replacing the oxidizer with hydrogen peroxide from oxygen can have higher hydrogen productivity than conventional autothermal reforming using oxygen as the oxidant.

Therefore, considering that the conventional process uses air as an oxidizing agent as an oxygen source, it can be understood that hydrogen can be produced at a higher concentration than autothermal reforming reaction using air as an oxidizing agent.

That is, the present invention produces hydrogen at a high concentration by using hydrogen peroxide as an oxidizing agent in a process of producing hydrogen to be used as a raw material for a fuel cell. Hydrogen peroxide is present in aqueous solution and decomposes into water vapor and oxygen.

Water vapor and oxygen are the raw materials required for autothermal reforming reactions. Because pure oxygen is difficult to produce and store, conventional autothermal reforming reactions using oxygen and water vapor are forced to use air as a source of oxygen.

When air is used for an existing autothermal reforming reaction, the above equation (4) is modified as follows.

In the case of CH ₄ + 0.44 (O ₂ + 3.76 N ₂ ) + 1.12H ₂ O = CO ₂ + 3.12H ₂ + 1.65 N ₂ , the concentration of hydrogen in the product is further diluted by nitrogen not participating in the reaction, .

Therefore, when the reforming fuel having a low hydrogen concentration is supplied to the fuel cell, the performance of the fuel cell is deteriorated. Further, in order to maintain the performance of the fuel cell, a post-treatment process for increasing the concentration of hydrogen is further required.

When hydrogen peroxide is used as an oxidizing agent, the effect of dilution of hydrogen by nitrogen can be eliminated, and hydrogen at a high concentration of 77.9% can be produced.

The process using hydrogen peroxide as an oxidant can produce a reformed fuel containing 77.9% of hydrogen, which can produce a reformed fuel containing a higher content of hydrogen than the 75.7% of the process using pure oxygen as the oxidant.

Hydrogen peroxide may be used as an oxidizing agent together with oxygen or air, and it is preferable to use hydrogen peroxide at a ratio of 0.1 to 1.0 equivalent to the carbon in the total hydrocarbons used in the actual hydrogen production process.

In the hydrogen production process, a typical catalytic reactor may be used. For example, a tubular reactor or a microchannel reactor may be used.

The fuel cell module 140 of the present invention can be applied to a fuel cell such as a molten carbonate fuel cell (MCFC), a solid oxide fuel cell (SOFC), a polymer electrolyte membrane fuel cell (PEMFC) Proton exchange Membrane Fuel Cell).

division Alkali (AFC) Phosphoric acid type (PFAC) Molten carbonate type (MCFC) Solid oxide type (SOFC) Polymer electrolyte type (PEMFC Direct methanol (DMFC) Electrolyte Alkaline phosphate lead carbonate ceramic Ion exchange membrane Ion exchange membrane Operating temperature (℃) 120 or less 250 or less 700 or less 1,200 or less Below 100 Below 100 efficiency(%) 85 70 80 85 75 40 Usage Space launch vehicle Medium building Medium and large size development Small-sized power generation Commercial small type Characteristic Durable enough Power generation efficiency is high Power generation efficiency is high Low temperature operation High power density Low temperature operation High power density

In Table 1, when the fuel cell module 140 is a molten carbonate fuel cell, carbon monoxide is supplied to the fuel cell module 140 together with hydrogen without removing carbon monoxide from the synthesis gas.

The reaction scheme for producing electricity by electrochemically reacting hydrogen and carbon monoxide in the fuel cell module 140 is as follows.

Fuel electrode: H ₂ + CO ₃ ^-2 ? H ₂ O + CO ₂ + 2e-

CO + CO ₃ ^-2 → 2CO ₂ + 2e - CO + H ₂ O → H ₂ + CO ₂

Air electrode: 0.50 ₂ + CO ₂ + 2e-? CO ₃ ^-2

The overall reaction in the fuel cell module _{(140): H2 + 0.5O 2} + CO 2 → H 2 O + CO 2

Here, the carbon monoxide supplied to the fuel cell module 140 together with hydrogen is used in a reaction to produce hydrogen by reacting with water at the fuel electrode. At this time, the generated carbon dioxide (CO ₂ ) is sent to the air electrode to be used for the reaction to generate carbon monoxide (CO ₃ ^-2 ) in the air electrode.

That is, when the fuel cell module 140 is a molten carbonate fuel cell, carbon dioxide generated in the process of generating electricity is circulated in the fuel cell without being discharged to the outside.

When the fuel cell module 140 is a molten carbonate fuel cell or a solid oxide fuel cell, some of the syngas supplied to the fuel cell module 140 is not electrochemically reacted in the fuel cell module 140 The high-temperature synthesis gas discharged from the fuel cell can be used to increase the power generation efficiency.

When the fuel cell module 140 is a solid oxide fuel cell, carbon monoxide is supplied to the fuel cell module 140 together with hydrogen without removing carbon monoxide from the synthesis gas. The reaction scheme for producing electricity by electrochemically reacting hydrogen and carbon monoxide in a solid oxide fuel cell is as follows.

_{^{Anode: H2 + O -2 → H 2}} O + 2e-

^{CO + O -2 → CO 2 +} 2e-

CO + H ₂ O → H ² + CO ₂

Air electrode: 0.5 O ₂ + 2e-? O ^-2

The overall reaction in the fuel cell module _{(140): H2 + 0.5O 2} → H 2 O

Here, the carbon monoxide supplied to the fuel cell module 140 together with hydrogen is used in a reaction to produce hydrogen by reacting with water at the fuel electrode. Carbon dioxide (CO ₂ ) generated at this time must be treated by a separate apparatus.

In the case where the fuel cell module 140 is a solid oxide type fuel cell, in order to treat carbon dioxide generated in the process of electrochemically reacting the synthesis gas in the fuel cell module 140, carbon dioxide And a carbon dioxide storage tank (not shown) for storing the carbon dioxide captured by the carbon dioxide trapper may be connected to the carbon dioxide trapper (not shown).

When the fuel cell module 140 is a polymer electrolyte fuel cell, only hydrogen is supplied to the fuel cell module. The reaction scheme for producing electricity by electrochemically reacting hydrogen in a polymer electrolyte fuel cell is as follows.

Anode: H2 - & gt ^; 2H ⁺ + 2e -

Air electrode: 0.50 ₂ + 2H ⁺ + 2e-? H ₂ O

The overall reaction in the fuel cell module _{(140): H2 + 0.5O 2} → H 2 O

In the process of electrochemically reacting the syngas in the fuel cell module 140, steam (H ₂ O) is generated, and this steam can be used for steam in the ship.

As described above, according to the present invention, in the offshore structure, the hydrogen production module generates hydrogen from the LNG stored in the LNG storage tank through the reforming reaction, and the fuel cell module generates hydrogen by supplying hydrogen, Unlike the plant for fuel cell power generation, it can reduce the construction cost of foundation, prevent pollution of forests and surrounding facilities, and solve environmental pollution problem of exhaust gas.

While the present invention has been particularly shown and described with reference to exemplary embodiments thereof, it is to be understood that the invention is not limited to the disclosed embodiments, but, on the contrary, Various modifications and variations are possible within the scope of the present invention.

100: Fuel cell power plant of offshore structure
110: LNG storage tank
120: hydrogen production module
130: hydrogen storage tank
140: Fuel cell module
150: power converter
160: electric storage unit

Claims (9)

Offshore structure;
An LNG storage tank provided in the offshore structure for storing LNG;
A hydrogen production module provided in the offshore structure to produce hydrogen from the LNG stored in the LNG storage tank;
A hydrogen storage tank provided in the offshore structure for storing hydrogen produced by the hydrogen production module; And
And a fuel cell module provided in the offshore structure to generate electricity by receiving hydrogen stored in the hydrogen storage tank. The method according to claim 1,
Further comprising a power converter for converting direct current (DC) produced by the fuel cell module into alternating current (AC), and an electric storage unit for storing the produced electricity. The method according to claim 1,
Wherein the LNG storage tank and the hydrogen storage tank are installed inside the offshore structure. The method according to claim 1,
Wherein the hydrogen production module is installed on an upper part of the offshore structure. The method according to claim 1,
And the fuel cell module is installed on an upper part of the offshore structure. Producing hydrogen from a hydrogen production module from LNG stored in an LNG storage tank;
Storing the hydrogen produced by the hydrogen production module in a hydrogen storage tank; And
And supplying hydrogen stored in the hydrogen storage tank to produce electricity in the fuel cell module. The method of claim 6,
Wherein the hydrogen production process of the hydrogen production module uses at least one of a steam reforming reaction, a partial oxidation reaction, and an autothermal reaction. The method of claim 6,
The steam reforming reaction is carried out in the presence of CH ₄ + H ₂ O = CO + 3H ₂ ego,
The partial oxidation reaction formula is CH ₄ + (1/2) O ₂ = CO + 2H ₂ Lt;
Wherein the autothermal reforming reaction scheme is CH ₄ + x O ₂ + (2-2x) H ₂ O = CO ₂ + (4-2x) H ₂ . The method of claim 8,
In the above autothermal reforming reaction scheme, when methane in the hydrocarbon is used as a reactant, the x value at which the total reaction heat (? H) becomes 0 is 0.44,
Wherein when the methane in the hydrocarbon is used as the reactant, the overall reaction formula is CH ₄ + 0.44 O ₂ + 1.12H ₂ O = CO ₂ + 3.12H ₂ .

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