KR101142473B1 - Molten Carbonate Fuel Cell System connected with Carbonate Refrigerant-generator and Heat Pump - Google Patents

Abstract

The present invention relates to a molten carbonate fuel cell system associated with a heat pump and associated with producing a carbon dioxide refrigerant that is a refrigerant of the heat pump. The present invention relates to a fuel cell comprising a fuel electrode, an air electrode, and an electrolyte; A combustor coupled to the anode to generate heat by burning exhaust gas containing carbon dioxide of the anode by air; A water separator connected to the combustor for separating water from waste gas containing carbon dioxide; And a carbon dioxide separator connected to the water separator to separate carbon dioxide from the waste gas from which water is separated, and comprising a compressor, a condenser, and an evaporator. And a carbon dioxide storage for storing carbon dioxide that has not been supplied to the condenser among the carbon dioxide passing through the compressor. Therefore, as a refrigerant of the heat pump, it is environmentally friendly, low ozone depletion index and global warming index, and it is possible to efficiently use carbon dioxide without flammability and toxicity.

Description

Molten Carbonate Fuel Cell System connected with Carbonate Refrigerant-generator and Heat Pump}

The present invention relates to a molten carbonate fuel cell system, and more particularly, to a technology for producing carbon dioxide refrigerant and for connecting a heat pump.

As climate change emerges as a global issue, countries are responding to it. Major countries have set targets for greenhouse gas reduction and introduced various policies for this purpose. Korea is also rapidly increasing fossil fuel consumption and carbon dioxide emissions due to industrialization and economic growth that began in the 1970s. Carbon dioxide is the biggest culprit of global warming produced by the oxidation of fossil fuels and by-products of combustion processes. As the Kyoto Protocol entered into force in 2005, Korea is in a situation where it cannot escape the obligation to reduce greenhouse gases, but it is insufficient to reduce the trend of increasing greenhouse gas emissions.

Meanwhile, the 1987 Montreal Protocol regulated the CFC (Chlorofluorocarbon) refrigerant and the HCFC (Hydro-Chlorofluorocarbon) refrigerant, and the 1997 Kyoto Protocol also regulated the HFC (Hydro-FluoroCarbon) refrigerant.

Recently, interest in environmentally friendly refrigerants such as hydrocarbons, carbon dioxide, ammonia and water has increased. In particular, carbon dioxide refrigerants are eco-friendly and have low Ozone Depletion Potential (ODP) and Global Warming Potential (GWP). No toxicity

However, the impact of refrigerants on the environment should be taken into account not only the refrigerant itself, but also the effects of carbon dioxide generated during power generation. The measure of the direct and indirect effects of these refrigerants is the Total Equivalent Warming Impact (TEWI). . In other words, it is important to minimize the TEWI by increasing the system efficiency while selecting eco-friendly refrigerant.

A large amount of carbon dioxide is generated as a combustion product for generating electric power in existing cogeneration plants, coal-fired power plants, and combined cycle power plants. Carbon dioxide is a major gas causing the greenhouse effect, and a technology for reducing carbon dioxide has been developed. In other words, there is a fuel cell technology capable of producing electric power using exhaust gas emitted from a power plant in connection with a carbon dioxide reduction technology. By using the exhaust gas at the cathode of the fuel cell, it is possible to reduce the carbon dioxide contained in the exhaust gas.

Fuel cells are solid polymer electrolyte fuel cells (PEMFC), solid oxide fuel cells (SOFC), molten carbonate fuel cells (MCFC), etc. Are distinguished. Molten carbonate fuel cell refers to a fuel cell in which the carbonate plays a role of ionic conductivity.

It is known to reduce the amount of carbon dioxide emitted from coal-fired power plants. In addition, the exhaust gas of the coal-fired power plant receives the exhaust gas and decomposes the carbon dioxide at the cathode to reduce the amount of carbon dioxide. , Save.

Heat pump can be considered as contributing to the cleanup of the urban environment due to the high energy conversion efficiency by various arrangements without burning fossil fuels in the consumer areas.In buildings with high personnel density, such as large buildings or department stores, the cooling load is larger than the heating load. Since the heating load itself is small due to the heat generated inside, the heat pump can be said to have advantageous thermal characteristics. A technology using a fuel cell as a heat source for driving such a heat pump has been developed. However, there was a system that directly connected the heat generated from the fuel cell to the heat source of the heat pump, but since there was no technology to start the heat pump by directly making carbon dioxide, the exhaust gas of the fuel cell, as a refrigerant, the greenhouse effect due to the carbon dioxide emission, etc. Could not solve the problem.

An object of the present invention is to solve the above-mentioned problems, to generate power by using the exhaust gas discharged from the coal-fired power plant as the fuel of the fuel cell and to provide or store the carbon dioxide generated from the fuel cell as the refrigerant of the heat pump It aims to do it.

In order to achieve the above object, the present invention provides an air electrode that generates carbonate ions by reacting the exhaust gas supplied from a coal-fired power plant and oxygen contained in the air, an electrolyte that absorbs most of the carbonate ions generated in the air electrode, and supplied from an electrolyte. A fuel cell comprising a fuel electrode reacting the carbonate ions with the fuel to produce a fuel exhaust gas including water and carbon dioxide; A combustor connected to the fuel electrode of the fuel cell and generating combustion heat while reacting and burning hydrogen and hydrocarbons in the gas discharged from the fuel electrode with air; A water separator separating water from the combustion gas containing carbon dioxide; And a carbon dioxide separator that separates carbon dioxide from a combustion gas containing carbon dioxide that passes through a water separator, and receives the refrigerant in a liquid state at low temperature and low pressure and evaporates the refrigerant from the liquid to gas by heat absorbed from the outside. It is supplied with an evaporator which changes to a state, a low-temperature low-pressure gaseous refrigerant formed in the evaporator, compresses it into a high-temperature high-pressure gas state, and receives a high-temperature high-pressure gaseous refrigerant formed in the compressor to the outside. A heat pump composed of a condenser for liquefying a refrigerant while releasing heat and changing it into a liquid state at low temperature and high pressure; And a carbon dioxide storage for storing carbon dioxide that has not been supplied to the compressor among carbon dioxide that has passed through the evaporator.

According to the carbon dioxide refrigerant production and heat pump-linked molten carbonate fuel cell associated with the heat pump according to the present invention, including a carbon dioxide storage, the exhaust carbon dioxide of the molten carbonate fuel cell through a carbon dioxide separator, such as home, building, industrial complex It can be used as a refrigerant in a heat pump system, so that carbon dioxide can be reduced and energy can be efficiently used.

Hereinafter, the same reference numerals will be described in detail with reference to the accompanying drawings, with reference to the same components preferred embodiments of the present invention. The terms and words used in the present specification and claims should not be construed as limited to ordinary or dictionary meanings and should be construed in accordance with the technical meanings and concepts of the present invention.

1 is a block diagram illustrating an example of a heat pump-linked molten carbonate fuel cell system according to an embodiment of the present invention used as a cooler. Referring to FIG. 1, the system is a coal-fired power plant 100, a fuel cell 200, a combustor 300, a water separator 400, a carbon dioxide separator 500, a heat pump 600, and a carbon dioxide storage 700. It includes.

The coal-fired power plant 100 emits exhaust gas containing carbon dioxide and is supplied to the cathode 220 of the fuel cell 200.

The fuel cell 200 is composed of a fuel electrode 210, an electrolyte 230 and an air electrode 220 to generate electric power by causing an electrochemical reaction to a fuel supplied from the outside.

The cathode 220 reacts with the exhaust gas supplied from the coal-fired power plant 100 and oxygen contained in the air 20 to generate carbonate ions. Air 20 is supplied from the inlet side of the cathode 220 of the fuel cell.

^{_{0.5O 2 + CO 2 + 2e -}} → CO 2- 3

In order to facilitate the above reaction, it is preferable to maintain the fuel cell 200 at a temperature of 550 ° C. or higher. In general, since the utilization rate of carbon dioxide in the cathode 220 is about 70% or more, the amount of carbon dioxide is reduced so that about 30% of carbon dioxide which does not participate in the reaction is discharged to the atmosphere through the pipe. The cathode waste gas 30 may be recycled back to the cathode 220 and recycled to reduce carbon dioxide emissions.

The electrolyte 230 absorbs most of the carbonate ions generated in the cathode 220. By absorbing almost 60% to 80% of the carbonate ions generated in the cathode 220, the amount of carbon dioxide discharged to the atmosphere can be reduced.

The anode 210 reacts the fuel 10 with carbonate ions supplied from the electrolyte 230 to generate a fuel exhaust gas including water and carbon dioxide.

^{_{H 2 + CO 2- 3 → H}} 2 O + CO 2 + 2e -

Here, the fuel 10 may be composed of hydrogen and a hydrocarbon component, and the hydrocarbon is supplied to the anode 210 by chemically reacting with a fuel composed of a hydrogen component by reforming by heat inside the fuel cell 200. . As a result of the reaction of the anode 210, carbon dioxide and steam (water) are generated, and together with unreacted hydrogen and hydrocarbons, an anode gas is formed.

The combustor 300 generates a combustion exhaust gas 40 including water and carbon dioxide while generating hydrogen and hydrocarbon in the anode exhaust gas discharged from the anode 210 by reacting with air 20 to generate combustion heat. In this case, the generated heat may be used to maintain the operating temperature of the molten carbonate fuel cell 200 at 550 ° C. to 600 ° C. as well as a heat source for operating the heat pump 600.

The water separator 400 is connected to the rear end of the combustor 300 to separate the water from the combustion gas (40). The combustion gas 40 contains carbon dioxide that is not reduced in the fuel cell 200. The steam, which is vaporized therein, is separated and discharged through the water pipe 50, or recycled to the fuel electrode 210. It can be resupplied with the steam necessary for the reaction. In addition, the high temperature steam may be used for the purpose of heat exchange in the system or a heat source of the heat pump 600.

The carbon dioxide separator 500 separates only carbon dioxide from a combustion gas containing carbon dioxide that passes through the water separator 400, and the waste gas from which carbon dioxide is separated is discharged to the atmosphere through the pipe 60. The separated carbon dioxide may be sent to the compressor 620 of the heat pump 600, or may be compressed and compressed and moved to a carbon dioxide storage 700. As described above, as an embodiment of the present invention, the carbon dioxide may be directly stored in the carbon dioxide storage 700 without being associated with the heat pump 600 and used as a system for manufacturing the carbon dioxide refrigerant.

The heat pump 600 includes an evaporator 610, a compressor 620, and a condenser 630, and may use carbon dioxide from the reaction of the fuel cell 600 as a refrigerant to carry heat.

The evaporator 610 is a device that receives a coolant in a low temperature low pressure liquid state and evaporates the coolant from a liquid to a gas by heat (Q _H ) absorbed from the outside to change the low temperature low pressure gas state.

The compressor 620 is supplied with the refrigerant of the low temperature low pressure gas state formed in the evaporator 610 through the four-way valve 640, and compresses it to change the gas state of the high temperature and high pressure. Compressor may be connected to the refrigerant supplied to the heat pump 600 directly from the carbon dioxide separator 500 to be replenished so that the energy can be efficiently used.

The condenser 630 receives the high-temperature, high-pressure gaseous refrigerant formed by the compressor 620 through the four-way valve 640 to liquefy the refrigerant while releasing heat (Q _L ) to the low-temperature, high-pressure liquid state. . The low temperature and high pressure liquid refrigerant formed in the condenser 630 is expanded by the expansion valve 650 and the pressure decreases to return to the low temperature low pressure liquid refrigerant and is supplied to the evaporator 620 to repeat the cycle. . Repeating this cycle, the heat pump 600 recovers the low temperature heat to generate the high temperature heat required by the power of the compressor 620.

If the heat pump 600 is to be used as a cooler, the evaporator 610 is installed to receive heat from the air of the indoor 660 (Q _H ) and the condenser 630 emits high temperature heat to the outdoor 670. Can be installed (Q _L ).

The carbon dioxide storage 700 stores the carbon dioxide remaining after the refrigerant (carbon dioxide) of the compressor 620 is supplied to the condenser 630 through the four-way valve 640, or by storing the carbon dioxide separated from the carbon dioxide separator 500 It is a place for use as a refrigerant when necessary.

2 is a block diagram illustrating an example of a heat pump-linked molten carbonate fuel cell system used as a heater according to an embodiment of the present invention. Referring to FIG. 2, the system is a coal-fired power plant 100, a fuel cell 200, a combustor 300, a water separator 400, a carbon dioxide separator 500, a heat pump 600, and a carbon dioxide storage 700. It includes.

When the heat pump 600 is to be used as a heater, the evaporator 610 may be installed to receive heat from the air of the outdoor 660 and the condenser 630 may be installed to radiate high temperature heat to the room 660. . Other configurations that are not shown and described in the drawings are easily understood by those skilled in the art to which the present invention pertains by the description of FIG. 1.

In the operation of the heat pump-linked molten carbonate fuel cell system as described above, the heat pump may be configured to drive heat pumps using waste heat, system cooling water, and high-temperature products of thermal power plants and fuel cells as driving heat sources.

3 is a block diagram showing a configuration capable of intermittently driving a heat pump-linked molten carbonate fuel cell system according to an embodiment of the present invention. Referring to FIG. 3, the system 1 including the fuel cell 200 and the heat pump 600 further includes a system start determining unit 800 connected to the carbon dioxide storage 700.

The system start determining unit 800 may include a carbon dioxide measuring instrument 810, an operation determining unit 820, and a switching unit 830.

The carbon dioxide amount measuring instrument 810 measures the amount of carbon dioxide in the carbon dioxide storage 700, and the operation determining unit 820 stops the operation of the system 1 when the amount of carbon dioxide measured by the carbon dioxide amount measuring instrument 810 is greater than or equal to a reference value. Or to separate and store the fuel cell 200 from the heat pump 600 to separate and store the carbon dioxide generated from the fuel cell 200, and when it is below the reference value, the system 1 may be determined to start operation. The switching unit 830 operates the opening and closing switch to operate the system according to the determination of the operation determination unit 820.

Although the cogeneration plant of an industrial complex and a molten carbonate fuel cell may be linked to continuously drive the system (1) of the present invention to be used as a high-efficiency carbon dioxide reduction device, the system may be configured to determine whether the system is started by measuring the amount of carbon dioxide. In addition, it is possible to connect large-scale molten carbonate fuel cells to produce large-capacity refrigerants in large areas by mainly producing heat pump refrigerants of local power sources. It can be intermittently maneuvered to supplement.

4 and 5 are block diagrams showing a structure in which a heat pump-linked molten carbonate fuel cell system according to an embodiment of the present invention is disposed on-site. In FIG. 4, the fuel is supplied from the thermal power plant 100 and supplied to cooling and heating of a building, a factory, and a home using a heat pump-linked molten carbonate fuel cell system 10 installed separately in a building, a factory, and a home. 5 has a structure that is supplied with fuel from the thermal power plant 100 and equipped with a large scale heat pump-linked molten carbonate fuel cell system 1 and operated to distribute the fuel to each building, factory, home, and the like.

While the preferred embodiments of the present invention have been shown and described, the present invention is not limited to the specific embodiments described above, and the present invention is not limited to the specific embodiments of the present invention, without departing from the spirit of the invention as claimed in the claims. Many modifications are possible to those skilled in the art. In addition, matters that can be easily inferred from the accompanying drawings are to be regarded as included in the contents of the present invention even if they are not described in the detailed description, and various modifications may be separately understood from the technical spirit or the prospect of the present invention. Will not be.

1 is a block diagram showing an example used as a cooler as a heat pump linked molten carbonate fuel cell system according to an embodiment of the present invention,

Figure 2 is a block diagram showing an example used as a heater as a molten carbonate fuel cell system heat pump associated in accordance with an embodiment of the present invention,

3 is a block diagram showing a configuration capable of intermittently driving a heat pump-linked molten carbonate fuel cell system according to an embodiment of the present invention; and

4 and 5 are block diagrams showing a structure in which a heat pump-linked molten carbonate fuel cell system according to an embodiment of the present invention is disposed on-site.

Claims (7)

delete A fuel cell that generates water and carbon dioxide and generates electric power using carbon dioxide, oxygen, and hydrogen; A combustor for generating water and carbon dioxide by combustion reaction of unreacted exhaust gas containing hydrogen in the fuel cell with air; A water separator separating water from waste gas including carbon dioxide discharged from the combustor; A carbon dioxide separator separating carbon dioxide from waste gas from which water is separated from the water separator; In the evaporator which receives the carbon dioxide in the liquid state of low temperature low pressure and absorbs it from the outside and evaporates the carbon dioxide from the liquid to the gas to change to the gas state of the low temperature low pressure, in the low temperature low pressure gaseous carbon dioxide formed in the evaporator and the carbon dioxide separator The compressor receives the separated carbon dioxide, compresses it, and converts it into a gaseous state of high temperature and high pressure; A heat pump composed of a condenser for changing to a state; And And a carbon dioxide reservoir for storing carbon dioxide that has not been supplied to the condenser among the carbon dioxide that has passed through the compressor. 3. The method of claim 2, A heat pump-linked molten carbonate fuel cell system comprising supplying carbon dioxide discharged from a thermal power plant to a fuel cell. The method of claim 2, wherein the heat pump A heat pump-linked molten carbonate fuel cell system characterized in that it is driven by the waste heat of the thermal power plant and fuel cells, system cooling water, high temperature products as a driving heat source. 3. The method of claim 2, A carbon dioxide amount measurer for measuring the amount of carbon dioxide of the carbon dioxide storage; Carbon dioxide amount measured by the carbon dioxide meter If it is above the reference value, the system is determined to stop the operation or the fuel cell is separated from the heat pump to determine to store and separate the carbon dioxide generated from the fuel cell, An operation determining unit which determines when the system is below a reference value to start operation; And And a switching unit for starting or stopping the starting of the system according to the determination of the operation determining unit. The method according to any one of claims 2 to 5, The evaporator is installed to receive heat from the air in the room, The condenser is installed in the heat pump coupled molten carbonate fuel cell system, characterized in that installed to discharge the high temperature heat. The method according to any one of claims 2 to 5, The evaporator is installed to receive heat from outdoor air, The condenser is installed in the heat pump coupled molten carbonate fuel cell system, characterized in that installed to discharge the high temperature heat.

Images