KR102254196B1 - Ammonia based solid oxide fuel cell system - Google Patents

Abstract

According to the present invention, an ammonia-based solid oxide fuel cell (SOFC) system enables efficient thermal management for high-temperature operation of the SOFC through optimization of configuration and through a method of operating the SOFC accordingly, and maximizes the efficiency of the SOFC system by reforming the ammonia supplied as fuel to the high-temperature SOFC into hydrogen and applying the hydrogen to the SOFC system according to the high-temperature thermal management.

Description

Ammonia based solid oxide fuel cell system

The present invention relates to a solid oxide fuel cell (SOFC) system based on ammonia, and more particularly, to a system for generating electricity by supplying ammonia as fuel to a high temperature solid oxide fuel cell (SOFC) system. will be.

A fuel cell, which is a device that directly converts chemical energy of an electrochemical reaction in which hydrogen and oxygen into water, into electric energy, has eco-friendly characteristics and high efficiency power generation, and thus, recent research has been actively conducted.

Depending on the electrolyte and operating temperature, various fuel cells include alkaline fuel cells (AFC), phosphoric acid fuel cells (PAFC), polymer electrolyte fuel cells (PEMFC), molten carbonate fuel cells (MCFC), and solid oxide fuel cells (SOFC). It is being developed in the form of.

Among them, a solid oxide fuel cell (SOFC) uses ceramic having ion conductivity as an electrolyte, and is a fuel cell that operates in a high temperature environment of about 500 to 1000°C, and has the advantage of having the highest efficiency among the above fuel cells. Show.

The fuel used in the SOFC may be used for hydrogenation reforming of a reformer installed inside a solid oxide fuel cell (SOFC) system as well as hydrogen.

However, since the hydrogen fuel is stored and transported in a gaseous phase, there is a disadvantage in that many additional facilities such as a gas pressurizing device, a high pressure container, and a hydrogen storage material are required. In addition, when CH-based fuels such as natural gas are reformed and used, pollutant gases of COx may be generated in a smaller amount than in the existing power generation system.

In contrast, ammonia, another fuel for fuel cells, is not only capable of hydrogenation reforming including nitrogen and hydrogen, but also does not generate any pollutant gases such as COx when applied to a fuel cell, and is easily stored in a liquid state, so it is more stored than hydrogen. And it has the advantage of high transfer efficiency.

However, until now, when ammonia is applied to a solid oxide fuel cell (SOFC), it remains in the research stage such as using an electric furnace as a heat source for the high-temperature operating environment of the solid oxide fuel cell (SOFC). ), an efficient system for thermal management of high temperature, which is an operating environment, has not been established, so development is urgently needed.

The ammonia-based solid oxide fuel cell (SOFC) system of the present invention enables efficient thermal management for high-temperature operation of the solid oxide fuel cell (SOFC) through the optimization of the configuration and the method of operating the SOFC system through the optimization. In addition, according to such high-temperature thermal management, ammonia supplied as fuel to a high-temperature solid oxide fuel cell (SOFC) is reformed into hydrogen and applied to the SOFC system, thereby maximizing the efficiency of the SOFC system.

Patent Document 1: Domestic Patent Publication No. 10-1340492

Patent Document 2: Japanese Laid-Open Patent Publication No. 2009-272117

Patent Document 3: Japanese Laid-Open Patent Publication No. 2007-328989

The present invention is an ammonia-based solid oxide fuel cell (SOFC) capable of high-temperature thermal management for the operation of a solid oxide fuel cell (SOFC), while having a low fuel price, convenient use, excellent energy storage efficiency, and high economic efficiency. ) A system and an operation method of the system are provided.

For the above object, the present invention includes a low temperature unit including a device related to supply and discharge of water and fuel; And a high-temperature unit including a device related to power generation, temperature increase, heat management, and gas treatment, wherein the low-temperature unit includes an inert gas supply device 1, a combustible fuel supply device 2, an ammonia fuel supply device 3, and water. A supply device 4, an air supply device 5 for a stack, an air supply device 6 for a burner, an exhaust gas treatment device 7, and a discharge hot water treatment device 8 are included, and a heat exchanger 1 is included in the high-temperature part. It provides an ammonia-based solid oxide fuel cell (SOFC) system comprising ~5(9), a vaporizer 10, a burner 11, a reactor 12, and a fuel cell stack 13.

The present invention also provides a method of operating an ammonia-based solid oxide fuel cell (SOFC) system including the following four steps of system configuration change for efficient thermal management of a high temperature, which is an operating temperature of a solid oxide fuel cell (SOFC). do.

-The first step: a purge step using an inert gas in the supply piping line and parts area of the combustible and ammonia fuel;

-Second step: a low temperature raising step of allowing the combustible fuel to flow through the fuel supply pipe line and burning it in a burner to supply an initial heat source;

-Third step: a high temperature raising step in which steam supply is started to prevent carbon deposition in the reactor and the fuel cell stack in the fuel supply piping line and to proceed with the reforming reaction of the combustible fuel; And

-Fourth stage: The operation stage of the SOFC system in which electric power is generated by converting the combustible fuel of the fuel supply piping line into ammonia fuel, that is, applying electric current.

The ammonia-based solid oxide fuel cell (SOFC) system of the present invention does not require additional expensive equipment compared to the existing hydrogen or CH-based fuel-based system, and is very economical because it has excellent energy storage efficiency, and is also a solid oxide fuel cell (SOFC). Not only has the advantage of being able to manage high-temperature heat for the operation of the battery, but also has the advantage of having great use in the field of new and renewable energy.

1 schematically shows the overall configuration of an ammonia-based solid oxide fuel cell (SOFC) system of the present invention.
2 is a first step in the operation method of the ammonia-based solid oxide fuel cell (SOFC) system of the present invention, the inactivation of the'Purge step of the fuel supply piping line for combustible and ammonia fuel and the configuration connected to the piping line with an inert gas' It schematically shows the gas flow of the gas and the flow of air supplied from the air supply device 5 for the stack in the first step.
3 is a low-temperature heating step in which a combustible fuel, which is a second step in the operation method of the SOFC system based on ammonia of the present invention, flows through the fuel supply piping line and burns in a burner to supply an initial heat source. Schematically shows the gas flow of combustible fuel in
4 is to prevent carbon deposition in the reactor and fuel cell stack in the fuel supply piping line, which is the third step of the operation method of the ammonia-based solid oxide fuel cell (SOFC) system of the present invention, and to allow the reforming reaction of the combustible fuel to proceed. It schematically shows the gas flow in the high-temperature heating stage in which steam supply starts
5 is a fourth step of the operation method of the ammonia-based solid oxide fuel cell (SOFC) system of the present invention, by converting the combustible fuel of the fuel supply piping line into ammonia fuel to produce electric power, that is, applying an electric current. It schematically shows the flow of ammonia fuel in the operation stage of the SOFC system.
6 shows a structure of a 3-way valve for separating moisture from exhaust gas generated from the fuel supply piping line in the third step, the high temperature raising step, into hot water.

Hereinafter, the configuration and operation method of the ammonia-based solid oxide fuel cell (SOFC) system of the present invention will be described in detail with reference to the accompanying drawings.

The drawings introduced below are provided as examples for sufficiently conveying the spirit of the present invention to those skilled in the art. Accordingly, the present invention is not limited to the drawings presented below and may be embodied in other forms. In addition, the same reference numbers throughout the specification indicate the same elements.

Unless otherwise defined in terms used in the following description, all terms (including technical and scientific terms) used in this specification will be used as meanings that can be commonly understood by those of ordinary skill in the art to which the present invention belongs. In addition, the singular form includes the plural form unless specifically defined in the sentence.

In the drawings of the present specification and the following description, the stack refers to a solid oxide fuel cell stack, and the operating temperature refers to a temperature at which the solid oxide fuel cell can perform a normal reaction, and the solid oxide fuel cell stack refers to fuel and air. It means a temperature at which a normal electrochemical reaction that generates electricity by receiving is performed. In addition, in the following description and accompanying drawings, descriptions of known functions and configurations that may unnecessarily obscure the subject matter of the present invention will be omitted.

The ammonia-based solid oxide fuel cell (SOFC) system of the present invention is characterized by circulating a heat source generated by ignition by supplying a combustible fuel to a burner device to raise the temperature to the operating temperature of the stack.

When the stack reaches the operating temperature, ammonia fuel is supplied through a fuel supply piping line separate from the supply piping line of the combustible fuel, and is supplied in a liquid phase and supplied to the reactor in a gaseous phase through a vaporizer. When the ammonia fuel is gaseous, it may be supplied by connecting a valve to the fuel supply piping line of the combustible fuel.

In addition, the vaporizer in which the vaporization reaction of the supplied ammonia is performed is arranged integrally with the burner to maximize the efficiency of heat transfer to the vaporizer by the high-temperature gas generated after passing through the stack.

In addition, the reactor in which the hydrogenation reforming reaction of the supplied ammonia is performed is integrally arranged with the heat exchanger 1 through which the hot gas generated after passing through the stack passes, thereby maximizing the efficiency of heat transfer from the heat exchanger 1 to the reactor.

Hereinafter, a configuration and a driving method for implementing the features of the present invention as described above will be described in detail with reference to the accompanying drawings.

The configuration of the ammonia-based solid oxide fuel cell (SOFC) system according to the present invention is schematically shown in FIG. 1, (a) a low temperature section; And (b) a high-temperature unit; and a control unit for controlling the operation of a solid oxide fuel cell (SOFC) system, and an inverter for processing and generated electricity are omitted.

(a) low temperature part

(a) The low temperature section includes a device related to supply and discharge of water or fuel, and includes an inert gas supply device (1), a combustible fuel supply device (2), an ammonia supply device (3), and a water supply device (4). , An air supply device 5 for a stack, an air supply device 6 for a burner, an exhaust gas treatment device 7, a discharge hot water treatment device 8, and the like.

Looking specifically at the above configurations, the inert gas supplied from the inert gas supply device 1 may be an inert gas that does not react with ammonia gas, combustible fuel gas and metal at high temperatures such as Ar, N2, He, and the like. The supply device may be a flow pump, MFC, or the like capable of controlling the flow rate of the inert gas, and may be a conventional supply device used in the art.

The combustible fuel supply device 2 is a device for supplying combustible fuel required to raise the temperature of the system by igniting combustible fuel in a burner, and is a flow pump, MFC, etc. that can control the flow rate of combustible fuel. It may be a conventional feeding device. As the combustible fuel, combustible gases such as hydrogen, propane, and methane-based gases that can be ignited by an ignition device by reacting with air may be used.

The ammonia supplied from the ammonia supply device 3 may be liquid or gaseous (a vaporizer may not be necessary in the case of a gaseous phase, as a purity of 99% or more, or containing 90% or less of water, such as a wastewater septic tank). ), the supply device is also a flow pump, MFC, etc. that can control the flow rate of supplied ammonia, and may be a conventional supply device used in the art.

The water supplied from the water supply device 4 is in the form of a liquid or gaseous phase, and in the case of supplying gaseous water, additional components necessary for the water vapor phase may be further provided, and these components are conventionally used in the art. It may be a phosphorus configuration. In addition, the device of the water supply device 4 may be a flow pump, an MFC, or the like, and may also be a conventional supply device used in the art.

The air supplied from the stack air supply device 5 and the burner air supply device 6 is air containing oxygen with an oxygen partial pressure of 0.2 or more, and the devices include a flow pump, MFC, and an MFC capable of measuring the flow rate of air. Air Blower, etc. In addition, the air supplied from the stack air supply device 5 and passed through the stack may be recycled as a heat source of the stack through the heat exchanger 3.

The exhaust gas treatment device 7 is a place to treat gases, water vapor, and air discharged through a fuel supply piping line (red line in Fig. 1) and an air supply piping line (blue line in Fig. 1), Each of these may be treated using a separate device in the exhaust gas treatment device 7 or may be treated using the same treatment device. Specifically, after the fuel exhaust gas and water vapor passing through the burner 11 in the fuel supply piping line are reduced in temperature through heat exchanger 2 and heat exchanger 5, the fuel exhaust gas is 3 installed in the exhaust gas treatment device 7 -The hot water is discharged to the outside through a way valve (refer to the valve in Fig. 6), and the hot water converted from steam is discharged to the discharged hot water treatment device 8 through the 3-way valve, and the discharged hot water treatment device 8 The discharged hot water can be used for other purposes. In addition, the high-temperature air that has passed through the stack of the air supply piping line and the heat exchanger 3 is discharged to the outside from the exhaust gas treatment device 7 through the heat exchanger 4, or the air discharge line of the exhaust gas treatment device 7 It can be recycled by connecting the burner air supply device 6 (not shown).

The discharged hot water treatment device 8 is a place where hot water, which is converted through heat exchangers 4 and 5 to cool the hot fuel gas generated in the operating situation of the system of the present invention, is discharged, and This is a place where the water vapor mixed with the fuel exhaust gas generated from the burner of the fuel supply piping line is converted through the heat exchanger 2 and the heat exchanger 5, and the hot water is discharged through the 3-way valve installed in the exhaust gas treatment device 7. The hot water discharged to the discharged hot water treatment device 8 may be used for other purposes.

(b) high temperature part

(b) The high-temperature section includes devices related to power generation, temperature increase, heat management, and gas treatment, and heat exchangers 1 to 5 (9), vaporizers 10, burners 11, reactors 12, and fuel cell stacks It includes (13).

Looking specifically at the above configurations, heat exchangers 1 to 5 (9) are devices for efficient thermal management of high-temperature areas, and according to each location and use temperature range, a shell & tube type, a double pipe type, and a flat plate Plate Type, etc. may be used.

Each use temperature range of the heat exchanger 1 to 5, heat exchanger 1 is RT ~ 800 ℃, heat exchanger 2 is RT ~ 650 ℃, heat exchanger 3 is RT ~ 800 ℃, heat exchanger 4 is RT ~ 400 ℃, Heat exchanger 5 is RT ~ 400℃.

The vaporizer 10 is a device having a temperature range of RT ~ 700 ℃ for causing a phase conversion of liquid ammonia to gaseous ammonia. The ammonia converted to the gas is supplied to the reactor, and the phase change is performed at 400°C or higher.

The burner 11 is a device having a use temperature range of RT ~ 900°C, and is used as a device that generates a heat source to reach the operating temperature from the beginning of the system, an ignition device required for ignition of combustible fuels, and flammability for combustion. It includes a fuel part and an oxygen supply part, and has a heat exchanger shape and a structure capable of uniform heat distribution inside.

The reactor 12 is a device with a use temperature range of RT ~ 800°C for decomposing supplied combustible fuel and ammonia fuel to convert it into hydrogen, and has a structure in the form of a heat exchanger, and the structure is filled with a catalyst in a certain area. It can be configured in a form. As the catalyst, metals and metal oxides including Co, Mo, Ni, Ru, Cs, etc. having catalytic activity may be used, and the hydrogenation conversion rate may be changed according to temperature and the composition and characteristics of the catalyst. In addition, the reactor 12 may be used for suppressing carbon deposition in the stack by generating a reforming reaction by a catalyst and steam when supplying a CH-based combustible fuel in step 3, which is a high-temperature raising step by providing a steam supply unit.

The fuel cell stack 13 includes a cathode and an anode region, and is a device having a temperature range of RT to 1000°C for converting a chemical reaction into electric power. The stack may be in a form in which cells composed of metal/ceramic materials and an electrolyte are stacked in multiple layers, and a stack that generates power of 1W to 5kW or more may be used depending on the cell area and the number of stacked cells.

The Water Trap 14 is a device that removes water from exhaust gas generated after power generation in the fuel cell stack 13, and the temperature range is RT to 900°C.

Another method of operating an ammonia-based solid oxide fuel cell (SOFC) system according to the present invention is characterized in that it includes the following first to fourth operation steps for the purpose of generating power by supplying ammonia, and FIGS. It is shown in 5.

The temperature of each device in each step is not fixed within the step, and may gradually rise or fall within a certain range.

In case of rise, the amount of applied current increases when the burner is ignited, the amount of flowing gas is increased, the reactor steam is cut off, and the electrochemical reaction of the stack is increased.(For the stability of the stack, the amount of power generation should be gradually increased to the target amount. When a heat source such as the degree of heat generation increases gradually, the heat source such as the degree of heat generation is added, it proceeds continuously until the thermal equilibrium of the entire system is established, and in the case of descending, when steam is supplied or when the fuel supply device is changed ( It may be generated depending on circumstances such as combustible fuel -> ammonia fuel conversion).

The first step is a purge step at the initial stage of operation of the system at room temperature, and in this case, air may be supplied to the stack as well, or air may be supplied in the next second step.

The purge is for removing the fuel supply piping line, materials of each component connected to the piping line, and residual oxygen and impurities that can react with the fuel gas remaining in the respective components using an inert gas.

The flow of the inert gas is indicated by a solid line (red) in FIG. 2, and the amount and time of supply of the gas for purge, that is, the inert gas to the fuel supply piping line, depend on the length of the piping and the capacity of the internal device. It can be different.

In detail, the flow of the inert gas is supplied from the inert gas supply device 1 to the fuel supply piping line at room temperature, and the reactor 12 and the fuel cell stack 13 pass through the vaporizer 10. The anode region passes in the order of the water trap 14, passes through the heat exchanger 1, the burner 11, the heat exchanger 2, and the heat exchanger 5, and is discharged through the exhaust gas treatment device 7.

The air supply to the stack is indicated by a solid line (blue) in FIG. 2, and air is supplied from the stack air supply device 5 to the air supply piping line at room temperature, so that the heat exchanger 2, the heat exchanger 3, and the fuel cell stack After moving in the order of the cathode region of (13), it passes through the heat exchanger 3 again, passes through the heat exchanger 4, and is discharged through the exhaust gas treatment device 7.

The second step is a low-temperature heating step, in which the system is initially heated by using a heat source obtained by igniting the combustible fuel supplied from the combustible fuel supply device 2 in the burner.

The fluid flow of the combustible fuel is indicated by a solid line (red) in Fig. 3, and the combustible fuel supplied from the combustible fuel supply device 2 passes through the stack and is ignited in the burner to transfer the heat source to the vaporizer. Circulation increases the temperature of the stack and the components inside the system.

Specifically, the combustible fuel supplied from the combustible fuel supply device 2 to the fuel supply piping line at room temperature is the vaporizer 10, the reactor 12, the anode region of the fuel cell stack 13, and the water trap 14. Passing in sequence, it moves to the burner 11 through the heat exchanger 1. At this time, the air supplied to the air supply piping line from the burner air supply device 6 or the exhaust gas treatment device 7 is supplied to the burner 11 together.

The combustible fuel and air supplied to the burner are ignited by the ignition device of the burner to raise the gas temperature of the burner 11. The heated gas transfers heat to the carburetor 10, and heat is transferred back to the combustible fuel continuously supplied from the combustible fuel supply device 2 to the carburetor to which the heat is applied, so that the temperature of the combustible fuel is raised to 400°C or higher. do. The elevated combustible fuel passes through the reactor 12 following the vaporizer 10, the anode region of the fuel cell stack 13, and the water trap 14 in that order, thereby raising the temperature of the heat exchanger 1 to 200°C or higher.

On the other hand, the gas heated by the ignition in the burner 11 passes through a heat exchanger 2 to increase the temperature of the air supplied from the stack air supply device 5 to 200°C or higher, and the gas that has passed through the heat exchanger 2 is a heat exchanger. After passing through 5, it is discharged to the exhaust gas treatment device 7.

More specifically, with respect to the heated air flow, the air supplied from the stack air supply device 5 to the air supply piping line is heated to 200°C or higher by receiving the heat source of the heat exchanger 2, and this is 200°C or higher. The heated air moves to the cathode region of the fuel cell stack 13 through the heat exchanger 3, and then moves to the heat exchanger 3 again. The air temperature during the movement is maintained above at least 150°C.

The air that has moved back to the heat exchanger 3 can be recycled as a heat source in the stack, and is also discharged to the exhaust gas treatment device 7 through the heat exchanger 4, or is connected to the burner air supply device 6 to be burned ( 11) Can be recycled as air.

As described above, the heat source generated from the burner circulates to raise the temperature of the entire system, and the supply of combustible fuel is maintained until the air that has passed through the heat exchanger 4 is heated to 100°C or higher.

The third step is a high temperature raising step, which is a step for raising the system to a high temperature operable temperature, and following the low temperature raising step of the second step, raising the temperature of the system to an operable high temperature.

The third step is shown in FIG. 4, and specifically, the combustible fuel supplied from the combustible fuel supply device 2 to the fuel supply piping line is the vaporizer 10, the reactor 12, and the fuel heated by the second step. Passes through the anode region of the battery stack 13 in the order of the water trap 14, passes through the heat exchanger 1, and moves to the burner 11. At this time, the air supplied to the air supply pipe line by being connected to the burner air supply device 6 or the exhaust gas treatment device 7 is supplied to the burner 11 together.

The combustible fuel and air supplied to the burner are ignited by the ignition device of the burner to raise the gas temperature of the burner 11.

The heated gas transfers heat to the carburetor 10 again, and heat is transferred to the combustible fuel continuously supplied from the combustible fuel supply device 2 to the carburetor to which the heat is applied, so that the temperature of the combustible fuel is 600°C or higher. The temperature rises. The elevated combustible fuel passes through the reactor 12 following the vaporizer 10, the anode region of the fuel cell stack 13, and the water trap 14 in that order, and raises the temperature of the heat exchanger 1 to 600°C or higher. .

On the other hand, the gas heated by ignition in the burner 11 passes through heat exchanger 2 to increase the temperature of the air supplied from the stack air supply device 5 to 550° C. or higher, and the above ignition is heated through heat exchanger 2. The gas passes through the heat exchanger 5 and is discharged to the exhaust gas treatment device 7.

More specifically, with respect to the heated air flow, the air supplied from the stack air supply device 5 to the air supply piping line is heated to 550°C or higher by receiving the heat source of the heat exchanger 2, and this is 550°C or higher. The heated air moves to the cathode region of the fuel cell stack 13 through the heat exchanger 3, and then moves to the heat exchanger 3 again. At this time, the (air) temperature of the heat exchanger 3 is 600°C or higher, and the (air) temperature of the cathode region of the fuel cell stack 13 is 550°C or higher.

The air moved back to the heat exchanger 3 is recycled as a heat source in the cathode region of the fuel cell stack 13, or is discharged to the exhaust gas treatment device 7 through the heat exchanger 4, or the air supply device 6 for a burner ) Can be recycled as air for the burner (11). At this time, the (air) temperature of the heat exchanger 4 is 200°C or higher.

On the other hand, when the internal temperature of the system of the present invention increases by a certain amount or more according to the circulation of the heat source in the second step, when the CH series is used as a combustible fuel, the catalyst material in the reactor 12 or the fuel cell stack 13 Carbon deposition may occur on the surface of metal materials such as pipes including the anode material of the anode.

Therefore, in order to prevent this, additional water must be supplied in the third step. The fluid flow of the supplied water is indicated by a solid line (light blue) in FIG. 4, and the water supplied from the water supply device 4 passes through the heat exchanger 4 and is converted into steam (steam) and supplied to the reactor 12.

Specifically, water from the water supply device 4 is supplied to the heat exchanger 4, which has reached 100° C. or higher, which is the steam generation temperature in the second step, and the generated steam is supplied to the reactor 12.

As described above, by supplying water vapor to the reactor 12 like a combustible fuel, a hydrogenation reforming reaction occurs by the combustible fuel and water vapor to prevent carbon deposition in the stack, etc., and in addition to this, it helps to increase the temperature by combustion of hydrogen by hydrogenation reforming. Will be given.

As described above, the heat source generated from the burner circulates to raise the temperature of the entire system to a high temperature, and gas supply is maintained until the temperature of the fuel cell stack 13 rises to 550°C or higher.

The fourth step is an operation step of generating power in the system.

The temperature of each component in the fourth step gradually rises through the thermal cycle of the system according to the power generation amount of the stack, that is, the applied current amount, and as mentioned above, the applied current amount gradually increases to the final target amount for the stability of the stack. . In general, the final hourly power generation during operation is operated in the range of 70 to 80% of the maximum limit power generation of the stack for stability.

In the fourth step, as shown in FIG. 5, the supply of combustible fuel to the fuel supply piping line is stopped, and the supply of ammonia is switched to the supply of ammonia through the ammonia supply device 3. The supplied ammonia is vaporized in a liquid state through the vaporizer 10 and decomposed into hydrogen and nitrogen in the reactor 12. The decomposed mixed gas is supplied to the anode region of the fuel cell stack 13 to be used as fuel for power generation. In addition, since the above carbon deposition does not occur when ammonia fuel is supplied, water vapor (steam) is not supplied to the reactor 12. Instead, water of the water supply device 4 is used for efficient thermal management of the exhaust gas of the fuel cell stack. By passing through heat exchangers 4 and 5, hot water generated therefrom can be utilized.

In the operation step of the fourth step, in detail, when the fuel cell stack 13 is heated to 550° C. or higher due to the heating action of the second step and the third step, the combustible fuel supply device 2 is connected to the fuel supply piping line. The supply of the combustible fuel is blocked, and instead the ammonia fuel of the ammonia supply device 3 is supplied.

The supplied ammonia is vaporized through the vaporizer 10 heated to 600° C. or higher, and moves to the reactor 12 heated to 600° C. or higher. The moved vaporized ammonia is decomposed into hydrogen and nitrogen by the catalyst of the reactor 12 and is used as an operating fuel for electricity production through a chemical reaction in the anode region of the fuel cell stack 13. At this time, the temperature of the stack may be raised to 700 °C or higher.

The gas inside the stack is heated due to the heat of the chemical reaction generated during the operation of the chemical reaction in the anode region of the fuel cell stack 13, and the heated exhaust gas after such operation is heated to 700°C or higher, passing through the heat exchanger 1 to the burner. Moving to (11), heat is transferred to the vaporizer (10). At this time, the temperature of the burner 11 is 500°C or higher. This is because in the fourth step, air supply from the burner air supply device 6 is cut off, so that ignition does not occur in the burner 11.

In addition, the unreacted gas including moisture discharged after the operation in the stack is removed through the water trap 14, and moves to the burner 11 through the heat exchanger 1 heated to 650°C or higher. At this time, the temperature of the burner 11 is 500°C or higher.

At this time, the burner air supply device 6 is cut off, and as the concentration of hydrogen decreases during operation of the stack, the burner is also stopped igniting.

In addition, the exhaust gas after the operation of the high-temperature fuel cell passing through the burner 11 passes through the heat exchanger 2 to maintain the air supplied from the stack air supply device 5 at 450°C or higher. The exhaust gas after the operation of the fuel cell passing through the heat exchanger 2 passes through the heat exchanger 5 and is discharged to the exhaust gas treatment device 7.

On the other hand, the air supplied from the stack air supply device 5 is heated to 450°C or higher by receiving a heat source from heat exchanger 2, and heated to 550°C or higher through heat exchanger 3 that is heated to 700°C or higher. 13) Move in the order of the cathode area. In addition, the air is discharged in the form of nitrogen gas having a low partial pressure of oxygen due to consumption of oxygen during the chemical reaction operation of the stack, and at the same time, it is discharged by absorbing some of the heat of the chemical reaction generated in the anode region.

The air exhaust gas in the form of nitrogen gas as described above passes through the heat exchanger 3 again and is supplied as a heat source to the air supplied to the stack, or is discharged to the exhaust gas treatment device 7 through the heat exchanger 4 of 200° C. or higher.

As seen above, when the supply of the combustible fuel is switched to the supply of ammonia fuel, the water supply device 4 is switched in the direction through the heat exchanger 4 and the heat exchanger 5, and the exhaust gas temperature of the fuel supply piping line and the air supply piping line It has a function of lowering the temperature, and the water absorbing heat can be used as hot water.

The ammonia-based solid oxidation fuel cell (SOFC) system of the present invention supplies an inert gas, combustible fuel, water, and ammonia to a single supply pipe line in the first to fourth step operation method as described above. This has the advantage of being concise.

The present invention is not limited to the above-described embodiments, and various modifications are possible without departing from the gist of the present invention claimed in the claims.

1. Inert gas supply device
2. Combustible fuel supply system
3. Ammonia supply device
4. Water supply
5. Air supply for stack
6. Air supply for burner
7. Exhaust gas treatment device
8. Discharge hot water treatment device
9. Heat exchanger 1~5
10. Carburetor
11. Burner
12. Reactor
13. Fuel cell stack
14. WT (water trap)

Claims (22)

A low temperature section (a) comprising a device related to the supply and discharge of water or fuel; In the ammonia-based solid oxide fuel cell (SOFC) system comprising a; and a high-temperature unit (b) including a device related to power generation, temperature increase, thermal management, and gas treatment,
The low temperature part (a) is an inert gas supply device (1), a combustible fuel supply device (2), ammonia supply device (3), a water supply device (4), an air supply device for a stack (5), an air supply device for a burner. (6), an exhaust gas treatment device 7, and a discharge hot water treatment device 8,
The high temperature part (b) includes a heat exchanger 1 to 5 (9), a vaporizer 10, a burner 11, a reactor 12, a fuel cell stack 13, and a water trap (WT) 14,
The heating is performed by supplying combustible fuel and air from the combustible fuel supply device 2 to the burner 11 and igniting the heat source to the vaporizer 10, the reactor 12, and the anode of the fuel cell stack 13 The system is heated up to the operating temperature of the fuel cell stack 13, including the step of circulating the zone, the water trap 14, the heat exchanger 1 (9-1), and the burner 11 in this order. Ammonia-based solid oxide fuel cell (SOFC) system. delete The ammonia-based solid according to claim 1, wherein the raising of the temperature further comprises the step of generating a hydrogenation reforming reaction using a combustible fuel and steam by supplying steam to the reactor (12) heated by the step. Oxide fuel cell (SOFC) system The ammonia-based solid oxide fuel cell (SOFC) system according to claim 1, characterized in that the air is supplied from an air supply device (6) for a burner or an exhaust gas treatment device (7). According to any one of claims 1, 3 and 4, the inert gas supply device (1) is inert of Ar, N ₂ , He, etc., which does not react with ammonia gas, combustible fuel gas and metal at high temperature. It is a device that supplies gas,
The combustible fuel supply device (2) is a device that supplies fuel required to raise the temperature of the system by igniting combustible fuel in a burner, and the combustible fuel is composed of hydrogen, propane, and methane-based gases that can be ignited by an ignition device by reacting with air. Is a combustible gas,
The ammonia supply device 3 is a device for supplying liquid or gaseous ammonia having a purity of 99% or more or containing 90% or less moisture, such as a wastewater septic tank,
The water supply device 4 is a device that supplies steam or water to the reactor 12,
The stack air supply device 5 and the burner air supply device 6 are devices for supplying oxygen-containing air with an oxygen partial pressure of 0.2 or more to the cathode region of the fuel cell stack 13 and the burner 11, respectively,
The exhaust gas treatment device 7 is a device that processes air, gas, and water vapor discharged from the fuel supply piping line and the air supply piping line,
The discharged hot water treatment device (8) is a device for discharging hot water in which water used to cool the high-temperature fuel gas generated in the operating state of the system is converted through heat exchangers 4 and 5 , Ammonia-based solid oxide fuel cell (SOFC) system According to claim 5, The exhaust gas treatment device (7) is provided with a 3-way valve, and the hot water converted from the fuel exhaust gas and water vapor passed through the burner (11) and lowered through the heat exchanger 2 and the heat exchanger 5 Ammonia-based solid oxide fuel cell (SOFC) system, characterized in that each is discharged through two passages of the 3-way valve The method according to any one of claims 1, 3, 4, wherein the heat exchangers 1 to 5 (9) are devices for efficient thermal management of the high-temperature area, and the temperature range of each heat exchanger 1 is RT to 800. ℃, heat exchanger 2 is RT ~ 650 ℃, heat exchanger 3 is RT ~ 800 ℃, heat exchanger 4 is RT ~ 400 ℃, heat exchanger 5 is RT ~ 400 ℃,
The vaporizer 10 is a device having a use temperature range of RT ~ 700 ℃ that causes a phase conversion of the supplied liquid ammonia to gaseous ammonia,
The burner 11 is a device that generates a heat source for raising the system temperature from the beginning of the system to the operating temperature of the stack, has a use temperature range of RT to 900°C, an ignition device required for ignition of combustible fuels, and combustible for combustion. It is a device that includes a fuel part and an oxygen supply part, and has a heat exchanger shape and a structure capable of uniform heat distribution inside,
The reactor 12 is a device that decomposes combustible fuel and ammonia fuel to convert it into hydrogen, and a catalyst of a metal or metal oxide including Co, Mo, Ni, Ru, Cs is filled in a certain region,
The fuel cell stack 13 includes a cathode and an anode region, may be in a form in which a cell composed of a metal/ceramic electrode and an electrolyte are stacked in multiple layers, and is a stack capable of producing power of 1W to 5kW or more,
The WT (water trap) 14 is an ammonia-based solid oxide fuel cell (SOFC) system, characterized in that it is a device for removing water from fuel exhaust gas generated after power generation in the fuel cell stack 13 The ammonia-based solid oxide fuel cell (SOFC) system according to claim 3, wherein after the temperature rises, the supply of combustible fuel and air is stopped, and ammonia is supplied in a gaseous form to the reactor through a vaporizer. The ammonia-based solid oxide fuel cell (SOFC) system according to claim 1, wherein the vaporizer is integrally arranged with a burner to maximize heat transfer efficiency to the vaporizer by high-temperature gas generated after passing through the stack. The ammonia-based solid oxide fuel cell (SOFC) system according to claim 1, wherein the reactor and the heat exchanger 1 are integrally arranged. Ammonia-based solid oxide fuel cell (SOFC) system including the following four operation steps
-The first step: a purge step using an inert gas in the supply piping line and parts area of the combustible and ammonia fuel;
-Second step: a low temperature raising step of allowing the combustible fuel to flow through the fuel supply pipe line and burning it in a burner to supply an initial heat source;
-3rd step: a high temperature raising step in which steam supply is started to prevent carbon deposition in the reactor and the fuel cell stack in the fuel supply piping line, and to proceed with the reforming reaction of the combustible fuel; And
-The fourth stage: The operation stage of the SOFC system in which electric power is produced by converting the combustible fuel of the fuel supply piping line into ammonia fuel. The method of claim 11, wherein in the first step, an inert gas, which is a purge gas, is supplied from an inert gas supply device (1) at room temperature to a fuel supply piping line, and a reactor (12), a fuel cell through a vaporizer (10). It passes in the order of the anode area of the stack 13, the water trap 14, passes through the heat exchanger 1, the burner 11, the heat exchanger 2, and the heat exchanger 5, and then discharges through the exhaust gas treatment device 7 Ammonia-based solid oxide fuel cell (SOFC) system, characterized in that The heat exchanger 2 according to claim 11, wherein during the first step, air is supplied to the stack, and the supplied air is supplied from the stack air supply device (5) to the air supply piping line at room temperature, Ammonia-based solid, characterized in that after moving in the order of the heat exchanger 3 and the cathode area of the fuel cell stack 13, passing through the heat exchanger 3 again, passing through the heat exchanger 4, and being discharged through the exhaust gas treatment device 7 Oxide fuel cell (SOFC) system The method of claim 11, wherein in the second step, the combustible fuel supplied from the combustible fuel supply device (2) to the fuel supply piping line at room temperature is a vaporizer (10), a reactor (12), and an anode of the fuel cell stack (13). The area passes in the order of the water trap (14), and moves to the burner (11) through the heat exchanger (1).At this time, the burner (11) is supplied with air from the burner air supply device (6) or the exhaust gas treatment device (7). Ammonia-based solid oxide fuel cell (SOFC) system, characterized in that air is also supplied to the supply piping line The method of claim 11, wherein the third step comprises: a vaporizer (10), a reactor (12), and a fuel cell stack in which the combustible fuel supplied from the combustible fuel supply device (2) to the fuel supply piping line is heated by the second step. Passes through the anode area of (13) in the order of the Water Trap (14), passes through the heat exchanger 1 and moves to the burner (11), at this time, the air supply device (6) for the burner or the exhaust gas treatment device (7) Ammonia-based solid oxide fuel cell (SOFC) system, characterized in that air supplied to the air supply piping line is supplied to the burner 11 at the same time. The method according to claim 14 or 15, wherein the combustible fuel and air supplied to the burner are ignited by the ignition device of the burner to raise the temperature of the gas of the burner (11), and the elevated gas is converted into a vaporizer (10). Heat is transferred again to the combustible fuel of the carburetor continuously supplied from the combustible fuel supply device 2, and the heated combustible fuel is transferred to the reactor 12, the anode region of the fuel cell stack 13, and water. Ammonia-based solid oxide fuel cell (SOFC) system, characterized in that the temperature of the heat exchanger 1 is raised by passing through the trap 14 in order. The exhaust gas according to claim 14 or 15, wherein the gas heated by the ignition of the burner (11) increases the temperature of the air supplied from the stack air supply device (5) through the heat exchanger 2, and then passes through the heat exchanger 5. The heated air is discharged to the processing unit 7 and is supplied to the cathode region of the fuel cell stack through the heat exchanger 3, and then passed through the heat exchanger 3 to be reused as a heat source in the fuel cell stack, or the heat exchanger 4 is used. Ammonia-based solid oxide fuel cell (SOFC) system, characterized in that it is discharged to the exhaust gas treatment device 7 The ammonia-based solid oxide fuel cell (SOFC) system according to claim 15, wherein in the third step, water vapor is further supplied to the reactor (12). The ammonia-based method according to claim 18, wherein the water vapor is generated by supplying water from a water supply device (4) to a heat exchanger 4 reaching 100°C or higher in the second step, the low temperature rising step. Solid Oxide Fuel Cell (SOFC) System The method of claim 11, wherein in the fourth step, the supply of the combustible fuel to the fuel supply piping line is stopped, and the supply of ammonia is switched to the supply of ammonia through the ammonia supply device (3), and the supplied ammonia is vaporized in a liquid state. ) Is vaporized and decomposed into hydrogen and nitrogen in the reactor 12, and the decomposed mixed gas is supplied to the anode region of the fuel cell stack 13 to be used as a fuel for a chemical reaction for power generation, Ammonia-based solid oxide fuel cell (SOFC) system The method of claim 20, wherein water vapor is not supplied to the reactor (12) in the fourth step, and instead, water from the water supply device (4) is passed through heat exchangers 4 and 5 for efficient thermal management of the exhaust gas of the fuel cell stack. Ammonia-based solid oxide fuel cell (SOFC) system, characterized in that The heat exchanger 5 according to claim 20, wherein in the fourth step, the high-temperature exhaust gas of the stack due to the chemical reaction is heated by heating the air supplied from the stack air supply device (5) through a burner and heat exchanger 2. After passing through, the heated air is supplied to the cathode region of the fuel cell stack through the heat exchanger 3 and then passed through the heat exchanger 3 to be reused as a heat source in the fuel cell stack, or Ammonia-based solid oxide fuel cell (SOFC) system, characterized in that it is discharged to the exhaust gas treatment device 7 through the heat exchanger 4

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