KR100674622B1 - Fuel cell power generation system - Google Patents

Abstract

A fuel cell power generation system is provided to save an initial installation cost by reducing pipes and devices, to enhance a utilization efficiency of fuel, and to prevent emission of exhaust gas containing sulfur components. The fuel cell power generation system comprises: a desulfurizer(100) for removing sulfur from fuel gas; a reformer(110) for generating gas abundant in hydrogen from the desulfurized fuel gas; a fuel cell stack(120) that reacts hydrogen in the fuel gas reformed in the reformer(110) with oxygen and carbon dioxide in the air and generates electricity; and a steam generator(130) that generates water vapor to be supplied to the reformer(110). The fuel gas is desulfurized in the desulfurizer(100), and then introduced into a reformer catalyst layer(110a) and a reformer burner(110b) of the reformer(100). The fuel gas introduced into the reformer catalyst layer(110a) is mixed with water vapor generated in the steam generator(130). The resultant mixture is reacted in the catalyst layer(110a) of the reformer(110), followed by introducing the reacted gas into a fuel electrode(120a) of the fuel cell stack(120). Reformer burner combustion gas of the reformer(110) is introduced into an air electrode(120b) of the fuel cell stack(120). Fuel electrode exhaust gas of the fuel cell stack(120) is introduced into the reformer burner(110b) via the steam generator(130). Air electrode exhaust gas of the fuel cell stack(120) is re-introduced into the air electrode(120b) via the steam generator(130).

Description

Fuel cell power generation system

1 is a schematic configuration diagram of a fuel cell power generation system according to the prior art,

2 is a schematic diagram of a fuel cell power generation system according to an exemplary embodiment of the present invention.

Explanation of symbols on the main parts of the drawings

100: desulfurizer 110: reformer

110a: reformer catalyst layer 110b: reformer burner

120: fuel cell stack 120a: anode

120b: air electrode 130: steam generator

140: catalytic combustion 150, 160: gas-liquid separator

101, 111, 112, 113, 121, 122, 123, 151: heat exchanger

11, 12, 13, 211, 211a: sulfur-containing fuel gas supply piping

211b: desulfurization fuel gas

14, 15, 16, 212, 213, 214: reformer fuel gas supply piping

17, 18, 217, 218: reformer burner fuel gas supply piping

21, 22, 23, 24, 25, 26, 221, 222, 223, 224, 225: water supply piping

27, 28, 29: water recirculation piping

31, 231, 231a: air supply piping

32, 232: reformer burner air supply piping

33, 34: catalytic combustion air supply pipe

41, 42, 241, 242: anode gas supply piping

51, 52, 53, 54, 251, 252: anode gas piping

61, 62, 63, 261, 262, 263: cathode gas supply piping

71, 72, 73, 74, 75, 76, 77, 78, 271, 272: cathode exhaust piping

81, 82, 83, 84, 281, 282, 283, 284: reformer burner flue gas piping

91, 291: carbon dioxide supply piping

The present invention relates to a fuel cell power generation system, and more particularly, to reduce the installation area by reducing the piping and the device, to reduce the initial installation cost, to increase the fuel utilization efficiency to reduce the operating cost, exhaust gas containing sulfur components The present invention relates to a fuel cell power generation system capable of reducing environmental pollution by blocking emissions.

In general, molten carbonate fuel cell power generation systems can use various fuels such as natural gas and coal gas, and produce electricity by an electrochemical reaction in which fuel is directly converted to electricity at a high temperature of 650 ° C. without a combustion process. Therefore, since there is no combustion process and electricity is directly produced from fuel, noise and air pollutant emission is low, and thus, it is attracting attention as a next generation power generation method.

1 is a view showing the configuration of a molten carbonate fuel cell power generation system of the prior art, the molten carbonate fuel cell power generation system of the prior art as shown in Figure 1 is a desulfurizer for removing sulfur from the natural gas fuel gas ( 100, a reformer 110 for generating a hydrogen-rich gas from the fuel gas, a molten carbonate fuel cell stack 120 for generating power by reacting hydrogen of the fuel gas generated in the reformer 110 with oxygen and carbon dioxide in the air, hydrogen Steam generator 130 for obtaining water vapor necessary for reforming the gas-rich gas, gas-liquid separators 150 and 160 for separating water from the exhaust gas of the anode 120a and the cathode 120b, anode exhaust gas and cathode exhaust gas. It is generally composed of a catalytic combustor 140 for combustion and recirculation and heat exchangers 101, 111, 112, 113, 121, 122, 123, and 151 for improving heat utilization efficiency.

In the prior art molten carbonate fuel cell power generation system having the above-described configuration, the utilization efficiency of fuel and air is determined by a predetermined load in the molten carbonate fuel cell stack 120, and a method of efficiently treating the remaining exhaust gas without reacting. The system was organized around.

Accordingly, the fuel cell power generation system according to the related art has the catalyst combustor 140 and the gas-liquid separators 150 and 160 installed to burn and recycle the anode exhaust gas 54 and the cathode exhaust gas 78. ) And the piping cost and equipment costs for installing the gas-liquid separator (150, 160), there is a problem that the initial installation cost is high because a large space is required for installation.

In addition, the above-described conventional fuel cell power generation system uses fuel gas that has not undergone desulfurization as the combustion gas of the reformer burner, and therefore, sulfur is included in the exhaust gas so that the exhaust gas of the reformer burner is converted into the cathode fuel gas of the fuel cell stack. Since it cannot be reused, it has a problem of polluting the environment because the exhaust gas containing sulfur components had to be released to the atmosphere.

In addition, the above-described conventional fuel cell power generation system allows the unreacted fuel gas contained in the anode exhaust gas of the fuel cell stack to be burned in a catalytic combustor and reused as the cathode fuel gas of the fuel cell stack. Due to the combustion consumption of the unreacted fuel gas present in the fuel gas utilization efficiency is lowered to reduce the fuel cost, there is a problem that the operating cost due to the fuel cost is excessively generated.

Accordingly, the present invention is to solve the above-mentioned problems in the prior art, unlike the fuel cell power generation system of the prior art is discharged from the reformer burner by performing desulfurization on the fuel flowing into the fuel cell power generation system in advance. Increasing fuel efficiency by introducing combustion gas rich in carbon dioxide into the cathode inlet gas of the fuel cell stack, and reusing exhaust gas containing unreacted fuel gas in the reformer catalyst bed as combustion gas of the reformer burner. Eliminates emissions of sulfur containing sulfur and does not cause environmental pollution, and reduces initial installation costs by reducing the installation space of the power generation system by eliminating auxiliary equipment including catalytic combustion and gas-liquid separators as in the prior art Fuel cell power generation To provide a system for that purpose.

The fuel cell power generation system of the present invention for achieving the above object,

Desulfurizer to remove sulfur from natural gas, fuel gas, reformer to generate hydrogen-rich gas from fuel gas, and fuel cell generated by reacting hydrogen contained in reformed fuel gas generated from reformer with oxygen and carbon dioxide in air A stack and a steam generator for producing steam for feeding to said reformer,

The fuel gas is introduced into the reformer catalyst layer and the reformer burner of the reformer after pre-sulfurization is performed by the desulfurizer, and the steam generated from the steam generator and the fuel gas introduced from the desulfurizer are mixed in the catalyst layer of the reformer. The reaction gas after the reaction flows into the anode of the fuel cell stack, the fuel exhaust gas of the fuel cell stack flows into the reformer burner via the steam generator, and the cathode exhaust gas of the fuel cell stack is the steam generator. It is characterized in that the connection is configured by the pipe to be re-introduced into the cathode via.

A sulfur-containing fuel gas supply pipe for supplying fuel gas to the desulfurizer and a reformer fuel gas supply pipe for supplying the reformer inlet fuel gas are each provided with a heat exchanger receiving heat by the reformer burner combustion gas pipe. .

The anode and the cathode of the fuel cell stack are configured to be connected to the steam generator so that the exhaust gas is supplied with heat to the steam generator.

The cathode exhaust gas is introduced into the cathode by a cathode gas supply pipe for inducing mixed gas after mixing with external inlet air, carbon dioxide, and the reformer burner combustion gas.

The air supply pipe for introducing the cathode gas supply pipe and the steam of the steam generator to the reformer is provided with a heat exchanger for supplying the heat of the cathode gas to the steam.

The fuel cell stack is characterized in that the molten carbonate fuel cell stack.

Hereinafter, the present invention will be described in more detail with reference to the accompanying drawings.

2 is a schematic configuration diagram of a fuel cell power generation system according to an embodiment of the present invention.

As shown in FIG. 2, a fuel cell power generation system according to an exemplary embodiment of the present invention includes a desulfurizer 100, a reformer 110, a molten carbonate fuel cell stack 120, a steam generator 130, and a heat exchanger 101. , 111, 112, 113, and 151 and pipes 211 to 291 connecting the above components.

The desulfurizer 100 removes sulfur components present in natural gas which is fuel gas.

The reformer 110 reforms the fuel gas to generate carbon monoxide and carbon dioxide as hydrogen and byproducts.

The molten carbonate fuel cell stack 120 generates electricity by reacting hydrogen generated in the reformer 110 with oxygen and carbon dioxide in the air.

The steam generator 130 is a device that generates steam by receiving pure water and heating it.

The heat exchanger (101, 111, 112, 113, 151) is a device for heat exchange between the hot pipes and cold pipes, consisting of a plurality of pipes, the outside of the pipe is a cylindrical body sealed structure Have

Next, the operation of the fuel cell power generation system according to an exemplary embodiment of the present invention will be described with reference to FIG. 2.

Natural gas, which is a fuel gas, is supplied by the fuel gas supply pipes 211 and 211a and heated in the heat exchanger 112, and then sulfur is removed while passing through the desulfurizer 100. The desulfurized fuel gas 211b from which the sulfur component is removed is divided through the reformer fuel gas supply pipe 212 and the reformer burner fuel gas supply pipe 217, respectively, and introduced into the reformer catalyst layer 110a and the reformer burner 110b.

The sulfur gas is removed from the fuel gas (211b) is introduced into the heat exchanger (101, 111) through the reformer fuel gas supply pipe 212 to the heat exchange between the anode gas supply pipe 241 and the reformer burner combustion gas pipe (281). Heated by At this time, the pure water introduced from the water supply pipe 221 is converted into water vapor in the steam generator 130 and then introduced into the heat exchanger 151 by the water supply pipe 224 to exchange heat with the cathode gas supply pipe 262. After performing the mixture with the reformer fuel gas introduced through the reformer fuel gas supply pipe 214 is introduced into the reformer catalyst layer (110a) of the reformer (110).

Water vapor introduced into the reformer 110 and the reformer fuel gas are reacted in the reformer catalyst layer 110a of the reformer 110 to be changed into a cathode supply gas in which hydrogen is a main component. The anode supply gas is introduced into the heat exchanger 101 through the anode supply gas pipe 241, and then flows into the anode 120a of the molten carbonate fuel cell stack 120 after heat exchange with the reformer fuel gas supply pipe 212. In this case, after reacting at the anode 120a of the molten carbonate fuel cell stack 120, unreacted anode exhaust gas flows into the steam generator 130 through the anode exhaust gas pipes 241 and 242 to perform heat exchange. The reformer burner 110b together with the air supplied from the outside through the desulfurized fuel gas 211b and the air supply pipe 231 and the reformer burner air supply pipe 232 introduced into the reformer burner fuel gas supply pipe 217. Hydrogen, carbon monoxide, and methane are all burned and converted into a carbon dioxide rich gas (reformer burner combustion gas).

The reformer burner combustion gas discharged after being burned by the reformer burner 110b is supplied to the heat exchangers 111, 112, and 113 through the reformer burner combustion gas pipes 281, 282, and 283, and then the reformer fuel gas supply pipe ( 213 and the cathode exhaust gas which is exchanged with the fuel gas supply pipe 211 and the water supply pipe 222 and then transferred by the reformer burner combustion gas pipe 284 and introduced through the cathode exhaust gas pipe 271. After mixing, the gas is recycled to the cathode gas supply pipe 261.

The air supplied from the outside is mixed with carbon dioxide and cathode gas flowing through the cathode gas supply pipe 261 introduced from the carbon dioxide supply pipe 291 through the air supply pipes 231 and 231 a to enrich the oxygen and carbon dioxide. After the supply gas is introduced into the heat exchanger 151 through the cathode supply gas pipe 262 and heated, it is introduced into the cathode 120b of the molten carbonate fuel cell stack 120. At this time, after reacting at the cathode 120a of the molten carbonate fuel cell stack 120, unreacted cathode exhaust gas is introduced into the steam generator 130 through the cathode exhaust gas pipe 271 to perform heat exchange. After mixing with the reformer burner flue gas introduced through the reformer burner flue gas pipe 284, it is recycled to the cathode gas supply pipe 261.

In the fuel cell power generation system of the present invention having the structure as described above, sulfur components are included in the fuel that has not reacted by preferentially desulfurizing and supplying the fuel introduced into the reformer catalyst layer 110a and the reformer burner 110b. Will not be. Therefore, the exhaust gas rich in CO ₂ of the reformer burner 110b flows into the cathode 120b of the fuel cell stack 120 to be recycled. Therefore, the present invention does not require a catalytic combustion device 140 for causing a catalytic reaction to enrich CO ₂ in the gas flowing into the cathode 120b of the fuel cell stack 120 as in the prior art.

Since the reformer burner combustion gas maintains a high temperature, the heat source of the heat exchanger 151 for maintaining the temperature of steam introduced to react with fuel (LNG, etc.) to generate hydrogen in the reformer catalyst layer 110a of the reformer 110. By using it, the energy utilization efficiency is improved.

In the case of the fuel cell stack 120, since the anode exhaust gas including the unreacted fuel gas discharged from the anode 120a of the fuel cell stack 120 also does not contain sulfur by undergoing a desulfurization process in advance, the reformer burner ( The utilization efficiency of the fuel can be improved by allowing the fuel to flow into the combustion gas of 110b) and reusing it.

The cathode exhaust gas of the cathode 120b of the fuel cell stack 120 is directly mixed with air and CO ₂ introduced from the outside without passing through a separate gas-liquid separator and then introduced into the reformer catalyst layer 110a of the reformer 110. After supplying heat for the heating of the steam to be re-introduced into the air electrode and reused to improve the energy utilization efficiency for steam generation.

The present invention as described above is configured to regenerate the carbon dioxide-rich exhaust gas of the reformer burner as the inflow gas of the cathode of the fuel cell stack by preferentially performing desulfurization on the fuel used to constitute the catalytic combustion and gas-liquid separator. It is possible to reduce the piping and equipment of the fuel cell power generation system by allowing the electricity to be produced smoothly without any, and thus, the installation space is reduced, thereby reducing the initial installation cost.

In addition, the present invention described above improves fuel utilization efficiency by allowing the anode exhaust gas containing the unreacted fuel gas discharged from the anode of the fuel cell stack to be reused as combustion fuel of the reformer burner, thereby reducing fuel costs. It provides the effect of reducing operating costs.

In addition, the present invention described above provides an effect of remarkably reducing environmental pollution by recycling the exhaust gas of the reformer burner without releasing it to the atmosphere unlike in the prior art.

Claims (4)

A desulfurizer for removing sulfur of fuel gas, a reformer for generating hydrogen-rich gas from the desulfurized fuel gas, a fuel cell stack for generating power by reacting hydrogen and oxygen and carbon dioxide in the air reformed in the reformer; It is provided with a steam generator for generating steam for supply to the reformer, The fuel gas is introduced into the reformer catalyst layer and the reformer burner of the reformer after pre-sulfurization is performed by the desulfurizer, and the fuel gas introduced from the steam generator and the fuel gas introduced into the reformer catalyst layer are mixed in the catalyst layer of the reformer. After the reaction, the reaction gas flows into the anode of the fuel cell stack, the reformer burner combustion gas of the reformer flows into the cathode of the fuel cell stack, and the anode exhaust gas of the fuel cell stack passes through the steam generator. And a cathode exhaust gas of the fuel cell stack is connected by a pipe to be re-introduced into the cathode via the steam generator. The heat exchanger of claim 1, wherein each of the sulfur-containing fuel gas supply pipe for supplying fuel gas to the desulfurizer and the reformer fuel gas supply pipe for supplying the reformer inlet fuel gas are heat supplied by the reformer burner combustion gas pipe. Fuel cell power generation system, characterized in that provided. The fuel cell power generation system according to claim 1, wherein the cathode exhaust gas is introduced into the cathode by an anode gas supply pipe for inducing mixed gas after mixing with external inlet air, carbon dioxide, and the reformer burner combustion gas. system. 4. The cathode gas supply pipe according to any one of claims 1 to 3, wherein the cathode gas supply pipe for inducing the cathode exhaust gas and the water supply pipe for introducing the steam of the steam generator to the reformer include heat of the cathode gas to the steam. A fuel cell power generation system, characterized in that a heat exchanger for supplying.

Images