JP2007122964A - Solid-oxide fuel cell power generation system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To uniformize the module temperature distribution in a solid-oxide fuel cell power generation system. <P>SOLUTION: The solid-oxide fuel cell power generation system has a module structure in which a plurality of cells composed of a solid-oxide fuel cell are assembled, and uses hydrocarbon fuel as an anode gas. The module temperature distribution is uniformized by supplying different anode gases respectively to parts where a module temperature is apt to rise, and parts other than the parts where the module temperature is apt to rise. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a solid oxide fuel cell power generation system in which a plurality of cells made of solid oxide fuel cells are assembled into a module structure, and more particularly to a power generation system using a hydrocarbon fuel as an anode gas.

  A fuel cell has an anode on one side with an electrolyte in between, a cathode on the other side, a fuel gas on the anode side, and an oxidant gas (mainly air) on the cathode side. It is a power generation device that generates electricity by electrochemically reacting a fuel and an oxidant. A solid oxide fuel cell, which is one type of fuel cell, has been studied because it has a high operating temperature of about 700 to 1000 ° C., high power generation efficiency, and easy use of exhaust heat.

  Usually, in order to obtain an electric output, a fuel cell is formed by stacking several tens to several hundreds of cells into an assembly (module). At the time of power generation, the cell generates heat due to Joule heat and can be operated thermally independently. For the cell, if the operating temperature is too low, the performance cannot be exhibited. Conversely, if the operating temperature is too high, the material is deteriorated and the life is deteriorated. Here, in the actual power generation state, a temperature distribution is generated in the module. Therefore, it is necessary to make the temperature distribution uniform.

  As a prior art described regarding the temperature control of a cell, there exists patent document 1, for example. In Patent Document 1, in a solid oxide fuel cell in which an internal reformer is disposed adjacent to a cell, means for adjusting the amount of heat conduction between the cell and the internal reformer is provided. It is described that temperature differences are prevented from occurring in the mass device. Thus, it is described that the temperature distribution can be suppressed from occurring in the cell surface temperature. However, Patent Document 1 does not describe the uniform temperature distribution of the module.

JP 2003-115307 A

  An object of the present invention is to achieve uniform temperature distribution of a module in a solid oxide fuel cell power generation system having a module structure in which a plurality of cells are assembled and using a hydrocarbon fuel as an anode gas.

  The present invention has a module structure in which a plurality of cells made of solid oxide fuel cells are assembled, and the temperature of the module increases in a solid oxide fuel cell power generation system in which hydrocarbon fuel is used as the anode gas. A different anode gas is supplied to the part which is easy to be processed and the other part so that the temperature distribution of the module is made uniform.

  Further, the present invention has a module structure in which a plurality of cells are gathered, and a solid oxide fuel cell power generation in which a gas obtained by reforming a hydrocarbon fuel with a reformer as an anode gas is supplied. In the system, a plurality of reformers are provided so that reformed gas having different hydrocarbon concentration, at least one of temperature and flow rate is generated, and the anode is different in the part where the temperature of the module is likely to rise and the other part Gas is supplied so that the temperature distribution of the module is made uniform.

  Further, the present invention has a module structure in which a plurality of cells are gathered, and a solid oxide fuel cell power generation in which a gas obtained by reforming a hydrocarbon fuel with a reformer as an anode gas is supplied. In the system, the module is divided into a plurality of zones according to the temperature rise, and the reformer for each zone, the temperature sensor for detecting the temperature in the zone, and the signal from the temperature sensor control the operation conditions of the reformer. A controller is provided to control the operating conditions of the reformer based on the signal from the temperature sensor so that the temperature distribution of the module is made uniform.

  In the present invention, it is desirable to partition the inside of the module into a plurality of areas according to the degree of temperature rise, for example, using a partition plate. Then, a gas with a higher hydrocarbon concentration or a gas with a lower gas temperature is supplied as the anode gas to the portion where the temperature is likely to rise, or in the case of the same gas composition and gas temperature as compared with the other portions. It is desirable to increase the gas flow rate.

  In the solid oxide fuel cell power generation system of the present invention, two or more kinds of anode gases having different hydrocarbon concentrations, gas temperatures, or gas flow rates are used, and the module is likely to have a temperature rise at the center portion other than the surrounding portions. In comparison with the above, a gas having a high hydrocarbon concentration or a low temperature is supplied, or the gas flow rate is increased. As a result, the temperature distribution can be made uniform throughout the module.

  First, a conventional general solid oxide fuel cell power generation system will be described with reference to FIGS.

  3A is a cross-sectional view showing a configuration of a solid oxide fuel cell power generation system, and FIG. 3B is a cross-sectional view taken along line AA of FIG. 3A. FIG. 4 is a cross-sectional view of a single cell of a solid oxide fuel cell. In a general solid oxide fuel cell, as shown in FIG. 4, an anode 80a is disposed outside a cell 80 via a cylindrical solid oxide electrolyte 80e, and a cathode 80c is disposed inside. It has a structure. In some cases, the arrangement of the anode and cathode is reversed. In FIG. 3B, for convenience, 36 cells are illustrated, but normally, several tens to several hundreds of cells are stacked and assembled in series or in parallel to generate power. This assembly is referred to as a module 30.

  An oxidant gas (usually air) is supplied as the cathode gas 90 to the cathode side of the cell 80. The oxidant gas passes through the header 91 for evenly distributing the gas to each cell, passes through the air introduction pipe 92, and reaches the cathode 80c. On the other hand, the anode gas 100 is usually supplied to the anode side after partially or entirely steam reforming a gas obtained by mixing a city gas, a hydrocarbon fuel such as LNG, LPG, and water vapor with the reformer 200.

  The cathode gas 90 and the anode gas 100 thus supplied generate an electrochemical reaction, thereby generating electricity and heat. With the heat generated at this time, the cell 80 is maintained at the operating temperature of 700 to 1000 ° C. Further, heat dissipation is suppressed by the heat insulating material 1 surrounding the module 30.

  However, if the anode gas 100 is supplied with the same gas composition, the same gas temperature, and the same gas flow rate, the module peripheral portion 30L during power generation tends to have a lower cell temperature than the module central portion 30H by the amount of heat dissipation. . Further, when the number of cells is increased in order to increase the size of the module, the temperature of the module central portion 30H is excessively increased, which may exceed the optimum operating temperature range. That is, the temperature distribution of the module 30 is not uniform. The present invention solves the problem of uneven temperature distribution of this module.

  1A and 1B show an embodiment of the present invention, in which FIG. 1A is a cross-sectional view showing an overall configuration, and FIG. 1B is a cross-sectional view taken along line AA. In this embodiment, two types of different anode gases are used, and the anode gas 100A is caused to flow through the module central portion 30H and the anode gas 100B is caused to flow through the module peripheral portion 30L. In FIG. 1, a partition plate 20 is provided in order to reliably separate and flow the anode gas 100A and the anode gas 100B, and the module central portion 30H and the module peripheral portion 30L are separated.

Here, the anode gas 100A and the anode gas 100B are preferably gases satisfying any one of the following conditions (1) to (3).
(1) The anode gas 100A has a higher hydrocarbon concentration than the anode gas 100B. (2) The anode gas 100A has a lower gas temperature than the anode gas 100B. The higher the hydrocarbon concentration in the anode gas, the more the steam reforming is performed at the anode of the cell, that is, the higher the endothermic amount due to internal reforming, the more cooling is achieved. It will be. Also, the low anode gas temperature cools the module. Further, when the gas flow rate is large in the same composition, the amount of heat absorbed by the internal reforming is increased, so that the cooling is performed more.

  That is, by supplying the anode gas satisfying at least one of the above (1) to (3) to each part of the module, the module central part 30H can be effectively cooled, and the temperature distribution can be made uniform. become.

  5A and 5B show another embodiment of the present invention, in which FIG. 5A is a cross-sectional view showing the entire configuration, and FIG. In the present embodiment, the reformer 200A and the reformer 200B are provided, and the reformed gas 100A generated by the reformer 200A is caused to flow to the module central portion 30H, and the reformed gas 100B generated by the reformer 200B is supplied. Was allowed to flow through the module periphery 30L. The reformer 200A generates a gas having a lower reforming rate (gas having a large endothermic amount) than the reformer 200B, and the reformer 200B has a gas having a higher reforming rate (an endothermic amount) than the reformer 200A. Producing less gas). By changing the reforming rate, the hydrocarbon concentration can be changed, and the gas temperature can also be changed. Specifically, when the reforming rate is increased, the gas has a low hydrocarbon concentration and a small endothermic amount, and the gas temperature increases.

  FIG. 2 schematically shows the relationship between the reforming temperature T of the steam reformer and the hydrocarbon concentration in the reformed gas. As shown in FIG. 2, the hydrocarbon concentration in the reformed gas can be changed by changing the reforming temperature. Therefore, as shown in FIG. 5, two or more types of reformers are installed, set to reforming temperatures corresponding to the anode gases 100A and 100B, and supplied to the anode, thereby effectively cooling the module high temperature part. Thus, as in the first embodiment, uniform temperature distribution of the module can be achieved.

  FIG. 6 shows an embodiment of a power generation system including a plurality of reformers and a reformer controller. A temperature sensor 2A is installed in the module central portion 30H, and a temperature sensor 2B is installed in the module peripheral portion 30L. The temperature of the module is detected by these temperature sensors and transmitted to the control device 300 as a detection signal 2S for control. A control signal 200AS is transmitted from the control device 300 to the reformer 200A, a control signal 200BS is transmitted to the reformer 200B, and the hydrocarbon concentration or gas temperature or gas flow rate of the reformed gas exiting from each reformer is controlled. To do. For example, when the temperature sensor 2A detects that the temperature of the module central portion 30H has become too high, the endothermic amount of the reformed gas 100A exiting from the reformer 200A is increased so as to cool the module central portion 30H. This control enables stable fuel cell operation.

  FIG. 7 shows an embodiment in which the present invention is applied to a module in which the anode gas is supplied in a horizontal direction. In this case, the module 30 has both end portions in the vertical direction as module peripheral portions 30L having a low temperature due to heat radiation, and the central portion in the vertical direction becomes a module central portion 30H having a high temperature. Therefore, in such an arrangement, the temperature distribution can be made uniform by flowing the reformed gases 100A and 100B as shown in FIG.

  Note that the gist of the present invention is to equalize the temperature distribution of the module by supplying two or more types of anode gas, in which at least one of the gas composition, gas temperature, or gas flow rate is changed, to the anode of the module. . Therefore, the shape of the cell is not limited to the cylindrical shape shown in FIG. The present invention can also be applied to a solid oxide fuel cell having a flat plate shape or other shapes.

  In the embodiment described above, the reformer is arranged outside the heat insulating material 1, but the arrangement of the reformer is not limited to this. For example, the reformer is arranged inside the heat insulating material. A vessel can also be provided.

The Example of this invention is shown, (a) is a whole block diagram, (b) is AA sectional drawing. It is a characteristic view showing the relationship between the reforming temperature and the hydrocarbon concentration in the reformed gas. 1 shows a general solid oxide fuel cell power generation system, in which (a) is an overall configuration diagram and (b) is an AA cross-sectional view. It is sectional drawing which showed the structure of the single cell. It is another Example of this invention, (a) is a whole block diagram, (b) is AA sectional drawing. It is a block diagram of the electric power generation system which shows the other Example of this invention. It is the schematic which showed another Example of this invention.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Thermal insulation material, 2A ... Temperature sensor, 2B ... Temperature sensor, 2S ... Detection signal, 20 ... Partition plate, 30 ... Module, 30L ... Module peripheral part, 30H ... Module center part, 80 ... Cell, 80a ... Anode, 80c ... cathode, 80e ... solid electrolyte, 90 ... cathode gas, 91 ... header, 92 ... air introduction pipe, 100 ... anode gas, 100A ... anode gas, 100B ... anode gas, 200 ... reformer, 200A ... reformer, 200B ... reformer, 200AS ... control signal, 200BS ... control signal, 300 ... control device.

Claims (12)

  In a solid oxide fuel cell power generation system having a module structure in which a plurality of cells made of solid oxide fuel cells are assembled and using hydrocarbon fuel as anode gas, the temperature of the module is likely to rise The solid oxide fuel cell power generation system is characterized in that different anode gas is supplied to the other parts and the temperature distribution of the module is made uniform.   2. The aspect of claim 1, wherein at least one of the hydrocarbon concentration, the gas temperature, and the gas flow rate of the anode gas is different between a portion where the temperature of the module is likely to rise and other portions. Solid oxide fuel cell power generation system.   2. The solid oxide fuel cell power generation system according to claim 1, wherein the inside of the module is divided into a plurality of areas in accordance with a temperature rise, and a different anode gas is supplied for each area.   4. The solid oxide fuel cell power generation system according to claim 3, wherein the inside of the module is partitioned into a plurality of areas by a partition plate.   4. The solid oxide fuel cell power generation system according to claim 3, wherein the module is partitioned into a central portion where the temperature is likely to rise and a peripheral portion other than the central portion.   2. The hydrocarbon concentration of the anode gas supplied to the portion where the temperature is likely to rise by increasing the hydrocarbon concentration of the anode gas between the portion where the temperature is likely to rise and the other portion of the module. A solid oxide fuel cell power generation system.   2. The gas temperature of the anode gas supplied to a part where the temperature of the anode gas is made to be different between a part where the temperature of the module is likely to rise and other parts, and the temperature of the anode gas supplied to the part where the temperature is likely to rise is lowered. Solid oxide fuel cell power generation system.   2. The gas flow rate of the anode gas supplied to the portion where the temperature is likely to rise is increased by making the gas flow rate of the anode gas different between the portion where the temperature of the module is likely to rise and the other portion. Solid oxide fuel cell power generation system.   In the solid oxide fuel cell power generation system, which has a module structure in which a plurality of cells are aggregated, and is supplied with a gas obtained by reforming a hydrocarbon-based fuel with an reformer as an anode gas, A plurality of reactors are provided so that reformed gas having different hydrocarbon concentration, at least one of temperature and flow rate is generated, and different anode gas is supplied to the portion where the temperature of the module is likely to rise and other portions. A solid oxide fuel cell power generation system characterized in that the temperature distribution of the module is made uniform.   10. The reformer according to claim 9, wherein one of the plurality of reformers is an anode gas supply source to a portion where the temperature of the module is likely to rise, and other reformers that supply the reformed gas to other portions. A solid oxide fuel cell power generation system characterized in that a reformed gas having a high hydrocarbon concentration, a low gas temperature, or a high gas flow rate is supplied.   In a solid oxide fuel cell power generation system having a module structure in which a plurality of cells are assembled, and a gas obtained by reforming a hydrocarbon-based fuel with a reformer as an anode gas is supplied. A reformer dedicated to each zone, a temperature sensor that detects the temperature in each zone, and a control device that controls the operating conditions of the reformer based on a signal from the temperature sensor. A solid oxide fuel cell power generation system characterized in that the temperature distribution of the module is made uniform by controlling the operating conditions of the reformer based on a signal from the temperature sensor.   12. The solid oxidation according to claim 11, wherein the hydrocarbon gas concentration, gas temperature, or gas flow rate of the anode gas supplied to each area is adjusted by a signal from a temperature sensor provided in each area of the module. Physical fuel cell power generation system.

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