KR101133543B1 - Fuel cell combined power system comprising carbon steam reformer - Google Patents

Abstract

The present invention exhibits high power generation efficiency even when a carbon vapor reforming apparatus for producing a mixed gas of hydrogen and carbon monoxide by reforming carbon obtained by carbonizing organic matters with steam and air, and a gas containing a small amount of hydrogen and carbon monoxide as fuel. A fuel cell cogeneration system, including a fuel cell, is provided. According to the present invention, a mixture of hydrogen and carbon monoxide generated by reforming carbon obtained by carbonizing organic matter contained in organic waste, wood-based raw materials, petroleum refining pitch etc. with water vapor and air can be used in a fuel cell instead of steam or gas turbine power generation. In addition, the fuel cell cogeneration system can be provided with high efficiency and eco-friendliness.

Fuel Cell Cogeneration System, Fuel Cell, Carbon Steam Reformer, Carbonization Process, Cogeneration

Description

Fuel cell cogeneration system with carbon steam reformer {FUEL CELL COMBINED POWER SYSTEM COMPRISING CARBON STEAM REFORMER}

The present invention relates to a fuel cell cogeneration system including a carbon steam reformer, and more particularly, by reforming carbon obtained by carbonizing organic matter contained in organic waste, wood based raw materials, petroleum refining pitch, etc. with steam and air. The present invention relates to a fuel cell cogeneration system capable of supplying hydrogen and carbon monoxide mixed gas to a fuel cell such as a molten carbonate fuel cell (MCFC) or a solid oxide fuel cell (SOFC) to be used as a fuel.

Recently, high efficiency and environmentally friendly fuel cells have been spotlighted as new electric energy sources. A fuel cell has a characteristic of continuously generating power by supplying fuel. The fuel cell mainly uses hydrogen as a fuel and generates water by generating water through oxidation of hydrogen and reduction of oxygen using oxygen in the air.

In particular, a fuel cell such as a molten carbonate fuel cell (MCFC) is a system that generates electricity at a temperature of 600 ° C. or higher because the electrolyte made of carbonate becomes molten at a high temperature to cause an electrode reaction. No expensive precious metal catalysts are needed. Therefore, it is easy to use a poisonous gas such as carbon monoxide, and a mixed gas of hydrogen and carbon monoxide can be used as a fuel, and high-temperature waste heat can also be used, so the efficiency is high.

In addition, solid oxide fuel cell (SOFC) uses oxygen ion transfer zirconia as electrolyte, and the electrode uses nickel oxide and conductive ceramic, so it is possible to generate power at high temperature above 700 ℃, and the mixture of hydrogen and carbon monoxide as fuel Can be used.

As a fuel used in such a fuel cell, natural gas mainly composed of methane is reformed into water vapor as shown in Chemical Formula 1, and converted to hydrogen and carbon monoxide.

CH ₄ + H ₂ O = 3H ₂ + CO

However, considering domestic realities that depend on imports of natural gas, economic problems may arise. In addition, it is possible to generate power using coal gasification gas, but domestic coal gasification technology is a situation that has not yet matured, it takes time to use.

An object of the present invention is to improve the effective use of the carbon components of all organic matter, the carbon vapor reforming apparatus that can produce a mixture of hydrogen and carbon monoxide by reforming the carbon obtained through the carbonization process of the organic matter with steam and air, The present invention provides a fuel cell cogeneration system that exhibits high efficiency and is environmentally friendly, including a fuel cell having high power generation efficiency even when the mixed gas containing a small amount of hydrogen and carbon monoxide is used as a fuel.

In order to achieve the above object,

A carbon steam reformer for reforming carbon into steam and air to produce a hydrogen and carbon monoxide mixed gas;

A dust remover for removing dust from the hydrogen and carbon monoxide mixed gas generated from the carbon steam reformer;

A fuel cell generating electricity by receiving a mixture of hydrogen and carbon monoxide in which dust is removed through the dust remover from an anode; And

Provided is a fuel cell cogeneration system including a catalytic steam reformer comprising a catalytic reactor for oxidizing unreacted hydrogen and carbon monoxide discharged from an anode of the fuel cell together with air using a fuel catalyst.

The present inventors have studied a fuel cell cogeneration system that can effectively use the carbon component of all organic materials. As a result, a mixture of hydrogen and carbon monoxide produced by carbonizing organic matter contained in organic waste, wood-based raw materials, petroleum refining pitch, etc. with water vapor and air is used as a molten carbonate fuel cell (MCFC) or a solid oxide fuel cell. We have developed a fuel cell cogeneration system that can be used as fuel by supplying fuel cells such as SOFC.

In one embodiment of the present invention, the carbon steam reformer receives carbon from a carbon feeder capable of a continuous supply. In addition, the mixture of hydrogen and carbon monoxide may be generated by reforming carbon into steam and air under an atmosphere of 700 ° C. or higher.

In this case, the carbon supplied to the carbon steam reformer may be carbon obtained by carbonizing organic waste, wood-based raw materials or petroleum refining pitch.

In addition, the fuel cell cogeneration system of the present invention may further include a heater for heating the carbon steam reformer so that the carbon steam reformer maintains an atmosphere of 700 ° C or more.

The fuel cell may be a molten carbonate fuel cell or a solid oxide fuel cell having high power generation efficiency even when a mixed gas containing a small amount of hydrogen and carbon monoxide is used.

The catalytic reactor may oxidize unreacted hydrogen and carbon monoxide discharged from the anode of the fuel cell together with air using a combustion catalyst to generate heat and exhaust gas. The heat and exhaust gases generated therefrom can be recovered and recycled to a heater that heats the carbon steam reformer.

On the other hand, the present invention provides a cogeneration method using a carbon steam reformer and a fuel cell comprising the following steps.

Reforming carbon with steam and air to produce hydrogen and carbon monoxide mixed gas (step 1);

Removing dust from the hydrogen and carbon monoxide mixed gas (step 2); And

Generating electricity from a fuel cell by receiving the hydrogen and carbon monoxide mixed gas from which the dust is removed (step 3).

Each step will be described below.

First, carbon is reformed with steam and air to produce hydrogen and carbon monoxide mixed gas (step 1). In step 1, carbon may be used as carbon obtained by performing a carbonization process on organic materials included in organic waste, wood-based raw materials, petroleum refining pitch, and the like.

In one embodiment of the present invention, in step 1, the carbon is supplied into a carbon steam reformer at 700 ° C. or higher, and then converted to hydrogen and carbon monoxide mixed gas by reforming according to a chemical reaction represented by the following Chemical Formula 2 using steam and air. can do.

C + H ₂ O = H ₂ + CO

The step of reforming the carbon with steam and air to produce a hydrogen and carbon monoxide mixed gas is preferably performed in the presence of carbonate to obtain a mixed gas containing a higher concentration of hydrogen and carbon monoxide.

As the carbonate, Li ₂ CO ₃ , Na ₂ CO _{3 ,} K ₂ CO ₃ Alkali metal carbonates such as but may be used, but is not limited thereto.

Next, dust is removed from the hydrogen and carbon monoxide mixed gas (step 2).

In the process of reforming carbon into steam and air to produce hydrogen and carbon monoxide mixed gas, dust may be mixed with the hydrogen and carbon monoxide mixed gas, thereby minimizing the influence on the fuel cell using the hydrogen and carbon monoxide mixed gas as fuel. Removing dust from the hydrogen and carbon monoxide mixed gas so as to be carried out.

Finally, the hydrogen and carbon monoxide mixed gas from which dust is removed in step 2 is supplied to the fuel cell to generate electricity (step 3).

As described above, after generating hydrogen by supplying hydrogen and carbon monoxide synthesis gas to the fuel cell in step 3, the alternating current may be converted into alternating current through a DC-AC converter.

In addition, the cogeneration method of the present invention generates electricity through the fuel cell in step 3, and recovers unreacted hydrogen and carbon monoxide in the pyrolysis gas supplied as fuel to oxidize with air through the catalytic reactor. It may further include.

Through the catalytic reactor, unreacted hydrogen and carbon monoxide may be oxidized together with air to generate heat, and the generated heat may be recovered by a flammable waste drying apparatus and used to dry flammable waste. In addition, the exhaust gas generated in the oxidation process in the catalytic reactor is recovered and supplied to the cathode of the fuel cell can be used for the electrochemical reaction.

The present invention can use the hydrogen and carbon monoxide mixed gas generated by reforming carbon obtained by carbonizing organic matter contained in organic waste, wood-based raw materials, petroleum refining pitch etc. with water vapor and air in fuel cells instead of steam or gas turbine power generation. In addition, the fuel cell cogeneration system can be provided with high efficiency and eco-friendliness.

Hereinafter, a fuel cell cogeneration system including a carbon steam reforming apparatus according to a preferred embodiment of the present invention will be described in detail with reference to the accompanying drawings.

1 is a view schematically showing the structure of a fuel cell cogeneration system including a carbon steam reformer of the present invention.

Among the components of the fuel cell cogeneration system 200, the carbon steam reformer 110 serves to generate hydrogen and carbon monoxide mixed gas by reforming carbon into steam and air.

The carbon steam reformer 110 converts the carbon supplied from the carbon supply device 130 that continuously supplies carbon into hydrogen and carbon monoxide mixed gas by reforming using steam and air introduced from the steam maker 100. The hydrogen and carbon monoxide mixed gas thus produced is used as fuel in a fuel cell.

In order to reform the carbon introduced from the carbon steam reformer 110 using steam and air, it is preferable to maintain the internal temperature of the carbon steam reformer 100 at a temperature of 700 ° C. or higher, and the carbon steam reformer 110. In order to maintain the temperature of the present invention), the present invention further includes a heater 120 for heating the carbon steam reformer 110.

The heater 120 heats the carbon steam reformer 110 with heat generated by burning fuel such as coal, oil, and gas. In addition, the carbon vapor reformer 110 may be heated by recycling the heat recovered from the catalytic reactor 170 to be described later.

The process of reforming the carbon introduced from the carbon steam reformer 110 by using steam and air is preferably performed in the presence of carbonate to obtain a mixed gas containing a higher concentration of hydrogen and carbon monoxide (the following test). See example 1).

As the carbonate, Li ₂ CO ₃ , Na ₂ CO _{3 ,} K ₂ CO ₃ Although alkali metal carbonates, such as these, are used, it is not limited to this.

The carbon obtained by carbonizing wood-based raw materials, petroleum refining pitch, organic waste, etc. is supplied into a carbon steam reformer including alkali metal carbonate at a temperature of 700 ° C. or higher, and then air is supplied to the carbon steam reformer together with steam. A mixed gas containing about 40% hydrogen concentration and about 9% carbon monoxide is generated. The gas having such a composition has power generation characteristics similar to those of a hydrogen concentration fuel in a molten carbonate fuel cell (MCFC) or a solid oxide fuel cell (SOFC), thereby enabling high efficiency power generation.

The hydrogen and carbon monoxide mixed gas obtained by reforming carbon introduced from the carbon steam reformer 110 using steam and air includes dust in the reforming process. Dust contained in a mixture of hydrogen and carbon monoxide reduces power generation efficiency when supplied to a fuel cell. Therefore, the hydrogen and carbon monoxide mixed gas is introduced into the dust remover 140 to remove dust contained in the hydrogen and carbon monoxide mixed gas.

The dust remover 140 may include a filter capable of removing dust from the mixed gas, for example, a porous ceramic filter, a metal filter, or the like.

As described above, the hydrogen and carbon monoxide mixed gas from which dust is removed through the dust remover 140 is supplied as fuel to the anode 162 of the fuel cell 160 and used for power generation.

The fuel cell 160 used in the present embodiment uses a molten carbonate fuel cell (MCFC) or a solid oxide fuel cell (SOFC), and a commonly used molten carbonate fuel cell (MCFC) or a solid oxide fuel cell (SOFC) is used. ) Can be used without limitation.

The molten carbonate fuel cell (MCFC) uses a porous electrode having a large surface area to smoothly proceed with oxidation of hydrogen and carbon monoxide and reduction of oxygen. The molten carbonate impregnated in the ceramic porous body between the two electrodes prevents direct contact between the fuel mainly composed of hydrogen and the oxidant composed of oxygen. In addition, the carbonate ions (CO ₃ ^{2 −} ) generated in the cathode (cathode) serve as a passage for moving to the anode (anode).

Molten carbonate fuel cell (MCFC) is a fuel cell that operates at high temperature, and the voltage-current and current- Power characteristics are shown.

In addition, the solid oxide fuel cell (SOFC) is made of nickel metal, in which oxidation of hydrogen and carbon monoxide starts from nickel oxide, and reduction of oxygen is performed by a conductive ceramic. In addition, an electrolyte such as an oxygen ion conductive zirconia is disposed between the anode, which is the fuel electrode, and the cathode, which is the air electrode, to prevent hydrogen or carbon monoxide from chemically reacting with oxygen.

However, when a molten carbonate fuel cell (MCFC) or a solid oxide fuel cell (SOFC) is used as one unit cell, the theoretical electromotive force is about 1V, which is not suitable for practical use. Therefore, the unit cells are laminated through a separator, which is a conductor, electrically connected in series, and used as a power generation system having a desired capacity by controlling the number of stacked cells.

That is, a molten carbonate fuel cell (MCFC) or a solid oxide fuel cell (SOFC) unit cell is composed of a pair of porous electrode plates (fuel electrode and air electrode) and an electrolyte plate present therebetween. Laminated via the plate. The separator provides electrical connection between the unit cells and provides a flow path of fuel gas to the anode, the anode, and a flow path of oxidant gas to the cathode, the cathode.

As described above, the molten carbonate fuel cell (MCFC) or the solid oxide fuel cell (SOFC) used in this embodiment is a fuel cell having a stacked structure. The molten carbonate fuel cell (MCFC) or the solid oxide fuel cell (SOFC) is provided with a manifold having a function of distributing and recovering the reaction gas so that the gas required for the reaction is supplied through the inlet manifold, Later it is discharged through the opposite manifold.

The fuel cell cogeneration system 200 including the carbon steam reformer of the present embodiment is a catalyst for oxidizing unreacted hydrogen and carbon monoxide discharged from the anode 162 of the fuel cell 160 with air using a combustion catalyst. Reactor 170.

The catalytic reactor 170 is a reactor for burning unreacted hydrogen and carbon monoxide. The catalytic reactor 170 generates a heat by installing a combustion catalyst inside the combustor and supplying a small amount of unreacted hydrogen and carbon monoxide discharged from the anode 162 of the fuel cell 160 together with air to oxidize it to generate heat. Let's do it. Therefore, the gas discharged from the catalytic reactor 170 is composed of air, water vapor, and carbon dioxide as a main component.

Heat generated by oxidizing unreacted hydrogen and carbon monoxide together with air in the catalytic reactor 170 is recovered by the heat exchanger 150 to supply a mixture of hydrogen and carbon monoxide supplied to the anode 162 of the fuel cell 160. Used to preheat. Alternatively, it is recovered to the heater 120 and used to heat the carbon steam reformer 110.

Exhaust gas from the catalytic reactor 170 including air, water vapor, carbon dioxide, etc. is supplied to the cathode 161 of the fuel cell 160 and used for the electrochemical reaction by oxygen components in the air, and the surplus gas exits the outlet. Is discharged through. In addition, the gas discharged through the outlet is recovered to the heater 120 and used for heating the carbon steam reformer 110.

The fuel cell cogeneration system 200 according to the present invention is disposed between the dust remover 140 and the fuel cell 160 to maintain a temperature of the hydrogen and carbon monoxide mixed gas supplied through the dust remover 140. 150 may be further included.

The heat exchanger 150 maintains the temperature of the mixed gas supplied from the dust remover 140 at a temperature suitable for the reaction and supplies it to the fuel cell 160.

In addition, the fuel cell cogeneration system 200 further includes a DC-AC converter 180 for converting the DC generated from the fuel cell 160 into AC.

Hereinafter, an experiment made through the fuel cell cogeneration system 200 described above will be described in detail.

In the carbon steam reformer of this embodiment, 20 g of activated carbon, which is generally available carbon, is added in the presence of 20 g of an alkali metal carbonate mixed with 62 mol% of Li ₂ CO ₃ and 38 mol% of K ₂ CO ₃ , at a temperature of 800 ° C. The air was reformed at a flow rate of 0.200 l / min and supplied with 0.265 l / min of water vapor. The resulting gas concentrations and flow rates are shown in Table 1 below. In addition, in the carbon steam reformer of the present invention, 20 g of carbon is added in the absence of the carbonate and reformed by supplying air at a flow rate of 0.200 l / min at a temperature of 800 ° C. and 0.265 l / min of steam. The concentration and flow rate of the generated gas are shown in Table 1 below.

By the above process, carbon was reformed into hydrogen and carbon monoxide in the presence of molten carbonate at a temperature of water vapor and 800 ° C., and then supplied to a molten carbonate fuel cell to generate electricity by the reactions shown in the following Chemical Formulas 3 and 4.

An anode (fuel _{^{electrode) H 2 + CO 3 2 -}} → H 2 O + CO 2 + 2e -

Cathode (air _{electrode) 1 / 2O 2 + CO 2} + 2e - → CO 3 2 -

2 is a hydrogen fuel cell using a conventional hydrogen fuel (H ₂ fuel, H ₂ : CO ₂ : H ₂ O = 69%: 17%: 14%) in a high temperature molten carbonate fuel cell as an example and the composition of the embodiment Steam reforming gas containing 14.0% water vapor in C gas, H ₂ : CO: CO ₂ : N ₂ : H ₂ O = 34.3%: 7.6%: 22.8%; 21.3%: 14.0%) is a graph showing the voltage and power characteristics according to the current in a 100 cm ² unit cell. As can be seen in Figure 2 when the carbon steam reforming gas is supplied to the molten carbonate fuel cell according to the embodiment of the present invention to generate electricity, it shows a slightly lower voltage-current characteristics compared to the conventional hydrogen fuel cell, the conventional hydrogen fuel in terms of power It shows about 2% lower performance than that of conventional hydrogen fuel cell, which shows similar power generation characteristics.

Gas component Carbon (20 g) + [Li ₂ CO ₃ (62 mol%) + K ₂ CO ₃ (38 mol%)] (20 g) Carbon (20g) Concentration (% by volume) Flow rate (l / min) Concentration (% by volume) Flow rate (l / min) H ₂ 34.3% 0.256 19.7% 0.093 N ₂ 21.3% 0.160 34% 0.160 CO 7.6% 0.056 3.4% 0.016 CO ₂ 22.8% 0.172 28.9% 0.136 H ₂ 0 14.0% 0.105 14.0% 0.066

As shown in Table 1, it can be seen that the amount of hydrogen and carbon monoxide generated is approximately doubled when the mixed carbonate and carbon are used together compared to the case where only carbon is used in the process of reforming carbon using steam and air. . In addition, when carbon was modified using carbon and mixed carbonates, it was observed through experiments that the mixed carbonates could be recovered with little consumption after carbon was converted to carbon monoxide. From this, it can be expected that continuous generation of carbon can be achieved by supplying carbon continuously with a minimum amount of carbonate supplementation to the carbon steam reformer.

While the present invention has been described through the preferred embodiments, it is apparent to those skilled in the art that various changes and modifications are possible only within the scope and spirit of the present invention, which are merely illustrative of the present invention. It should also be understood that it belongs to the appended claims.

1 is a view schematically showing the structure of a fuel cell cogeneration system including a carbon steam reformer of the present invention.

FIG. 2 shows a hydrogen fuel cell using conventional hydrogen fuel (H ₂ fuel, H ₂ : CO ₂ : H ₂ O = 69%: 17%: 14%) in a high temperature molten carbonate fuel cell, and the composition of the embodiment. Carbon steam reforming gas containing 14.0% water vapor (C gas, H ₂ : CO: CO ₂ : N ₂ : H ₂ O = 34.3%: 7.6%: 22.8%; 21.3%: 14.0%) is a graph showing the voltage and power characteristics according to the current in a 100 cm ² unit cell.

Explanation of symbols on the main parts of the drawings

200: fuel cell cogeneration system 100: steam generator

110: carbon steam reformer 120: burner

130: carbon supply 140: dust removal

150: heat exchanger 160: fuel cell

161: anode 162: cathode

170: catalytic reactor 180: DC-AC converter

Claims (21)

A carbon steam reformer for reforming carbon into steam and air to produce a hydrogen and carbon monoxide mixed gas; A dust remover for removing dust from the hydrogen and carbon monoxide mixed gas generated from the carbon steam reformer; A fuel cell generating electricity by receiving a mixture of hydrogen and carbon monoxide in which dust is removed through the dust remover from an anode; And It includes a catalytic reactor for oxidizing the unreacted hydrogen and carbon monoxide discharged from the anode of the fuel cell with air using a fuel catalyst, The catalytic reactor generates heat and exhaust gas by oxidizing unreacted hydrogen and carbon monoxide discharged from the anode of the fuel cell with air using a combustion catalyst. A fuel cell cogeneration system including a carbon steam reformer, wherein the exhaust gas generated from the catalytic reactor is supplied to a cathode of the fuel cell and used for an electrochemical reaction. The method according to claim 1, The carbon steam reformer is connected to a carbon supply device and is supplied with carbon to reform the carbon into steam and air under an atmosphere of 700 ° C. or higher to supply hydrogen and carbon monoxide mixed gas. Power generation system. The method according to claim 1, A fuel cell cogeneration system including a carbon steam reformer, wherein the carbon steam reformer includes a carbonate therein. The method of claim 3, A fuel cell cogeneration system including a carbon steam reformer, wherein the carbonate is an alkali metal carbonate. The method according to claim 1, A fuel cell cogeneration system comprising a carbon steam reformer, wherein the carbon supplied to the carbon steam reformer is carbon obtained by carbonizing an organic waste, wood-based raw material, or petroleum refining pitch. The method according to claim 1, And a heater for heating the carbon steam reformer such that the carbon steam reformer maintains an atmosphere of 700 ° C. or higher. The method according to claim 1, A fuel cell cogeneration system including a carbon steam reformer, further comprising a steam producing apparatus for supplying steam to the carbon steam reformer. The method according to claim 1, The fuel cell cogeneration system including a carbon steam reformer, characterized in that the molten carbonate fuel cell or solid oxide fuel cell. delete The method according to claim 1, A fuel cell cogeneration system including a carbon steam reformer, wherein the heat generated from the catalytic reactor is recovered and supplied to a heater for heating the carbon steam reformer. delete The method according to claim 1, A fuel cell including a carbon steam reformer, wherein the exhaust gas generated from the catalytic reactor is supplied to a cathode of the fuel cell and used for an electrochemical reaction, and then recovered by a heater to be used for heating a carbon steam reformer. Cogeneration system. The method according to claim 1, A fuel cell cogeneration system including a carbon steam reformer, the heat exchanger disposed between the dust remover and the fuel cell to maintain a temperature of the hydrogen and carbon monoxide mixed gas supplied to the fuel cell through the dust remover. Power generation system. The method according to claim 1, And a direct current (AC) -AC converter for converting direct current generated from the fuel cell into alternating current. Reforming carbon with steam and air to produce hydrogen and carbon monoxide mixed gas (step 1); Removing dust from the hydrogen and carbon monoxide mixed gas (step 2); And Receiving the dust-removed hydrogen and carbon monoxide mixed gas to generate electricity from a fuel cell (step 3); Generating electricity from a fuel cell by receiving a mixture of hydrogen and carbon monoxide in step 3, and then oxidizing unreacted hydrogen and carbon monoxide together with air using a catalytic reactor to generate heat and exhaust gas; , A co-generation system using a carbon steam reformer and a fuel cell, wherein the exhaust gas generated from the catalytic reactor is supplied to a cathode of the fuel cell and used for an electrochemical reaction. 16. The method of claim 15, Step 1 of reforming the carbon into steam and air is a carbon steam reformer and a cogeneration method using a fuel cell, characterized in that carried out in a carbon steam reformer including carbonate in an atmosphere of 700 ℃ or more. 16. The method of claim 15, In step 3, the fuel cell used is a molten carbonate fuel cell or a solid oxide fuel cell, characterized in that the carbon steam reforming device and the cogeneration method using the fuel cell. delete 16. The method of claim 15, Heat generated in the catalytic reactor is recovered to be used to heat the carbon steam reforming unit, characterized in that the carbon steam reformer and the cogeneration method using a fuel cell. delete 16. The method of claim 15, The exhaust gas generated from the catalytic reactor is supplied to the cathode of the fuel cell and used in the electrochemical reaction, and then recovered by a heater to be used for heating the carbon steam reformer and the fuel cell. Cogeneration method used.

Images