JP2010238593A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell system capable of preventing oxidation of a fuel battery cell and restraining generation of heat variations on the fuel battery cell and the whole cell stack at the time of starting and smoothly and effectively transferring from a steam reforming reaction to a partial oxidation reforming reaction. <P>SOLUTION: The fuel cell system FCS includes a fuel cell module FCM having a power generation chamber FC1 arranging a plurality of fuel battery cells CE, a combustion chamber FC2 arranged above the power generation chamber FC1, a steam reformer RFS performing steam reforming of a fuel gas at the time of a power generation mode, and a partial oxidation reformer RFP performing partial oxidation reforming of the fuel gas at the time of a starting mode and an operation stop mode. The partial oxidation reformer RFP is arranged outside a container where the power generation chamber FC1, the combustion chamber FC2, and the steam reformer RFS are stored, and is arranged in series with the steam reformer RFS at a downstream side of the steam reformer RFS. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a fuel cell system including fuel cells.

  Conventionally, there is a solid oxide fuel cell (hereinafter also referred to as SOFC) as a kind of fuel cell. As a fuel cell system including this fuel cell, for example, the fuel cell is formed into a bottomed or bottomed cylindrical shape and the like, and a fuel gas containing hydrogen is passed inside or outside thereof, and oxidation is performed on the opposite side. What makes an electric power generation reaction by passing agent gas (air) is known. As the fuel gas supply source, a gas to be reformed such as city gas is usually used. Therefore, a steam reforming reaction (SR: Steam Reforming) is caused by a reformer to obtain a hydrogen-rich fuel gas. ing.

  As a problem associated with the operation of the fuel cell system including such a fuel cell, oxidation of the fuel cell in the initial start (operation start period) and the operation stop period can be cited. Further, since the steam reforming reaction (SR) is an endothermic reaction, if the steam reforming reaction (SR) is performed immediately at the beginning of the start of the fuel cell system, the temperature of the fuel cell module does not rise, It is also known that it does not rise to a stable operating temperature. Therefore, at the beginning of startup, only the air and the gas to be reformed are sent to the reformer, and a partial oxidation reforming reaction (POX: Partial Oxidation Reforming) is performed as an exothermic reaction. When the temperature reaches about 700 ° C., the steam reforming reaction (SR) is switched to perform efficient power generation. During the shutdown period, the steam reforming reaction (SR) is changed to the partial oxidation reforming reaction (POX). An operation method of switching and preventing oxidation of the fuel cell is performed. (For example, refer to Patent Document 1).

JP 2005-293951 A

  In the fuel cell system described in Patent Document 1 described above, when the partial oxidation reforming reaction (POX) is performed in the partial oxidation reformer at the beginning of startup, the temperature of the steam reformer reaches the reforming temperature. In addition, when the partial oxidation reforming reaction (POX) is switched to the steam reforming reaction (SR), the steam reformer performs efficient power generation and stops the fuel cell system, the steam reforming reaction (SR ) To partial oxidation reforming reaction (POX), and partial oxidation reforming reaction (POX) is performed in the partial oxidation reformer.

  By the way, the partial oxidation reforming reaction (POX) is performed at about 300 ° C. or higher. However, in the fuel cell system described in Patent Document 1, the partial oxidation reformer that performs the partial oxidation reforming reaction (POX) is a fuel. Since it is arranged in the battery module, when shifting from the power generation mode in which efficient power generation by the steam reforming reaction (SR) is performed to the operation stop mode in which the fuel cell system is stopped, the partial oxidation reforming is performed. The vessel is maintained at a temperature at which a partial oxidation reforming reaction (POX) can be performed by heat generated by the power generation, and can immediately shift from the power generation mode to the operation stop mode.

  On the other hand, the partial oxidation reformer is usually heated to about 300 ° C. or higher in a short time from the start of startup, but the power generation temperature range of the fuel cell is about 650 ° C. or higher, preferably 700 ° C. or higher. The temperature increase rate of the fuel cell is very slow compared with the temperature increase rate of the partial oxidation reformer, and even if the partial oxidation reformer reaches 300 ° C. or higher, the temperature of the fuel cell is less than 50 ° C., or Usually around room temperature.

  However, as in the fuel cell system described in Patent Document 1, both a steam reformer that performs a steam reforming reaction (SR) and a partial oxidation reformer are disposed in the fuel cell module. In the case of a configuration arranged at a position close to the oxidation reformer, the temperature of the fuel cell rises when the partial oxidation reformer is heated in order to perform a partial oxidation reforming reaction (POX) at the beginning of startup. Before, the temperature of the partial oxidation reformer becomes 300 ° C. or higher, and the region of the fuel cell that receives the radiant heat from the partial oxidation reformer is locally heated. For this reason, a high-temperature part and a low-temperature part are generated in the fuel cell (heat unevenness is generated), and there is a possibility that the fuel cell is easily damaged. Further, when focusing on the entire cell stack composed of a plurality of fuel cells, the temperature of the fuel cells arranged near the partial oxidation reformer increases, and the high temperature portion is also unevenly distributed in the entire cell stack. Temperature distribution may occur, and stable operation may not be possible.

  The present invention has been made in view of such circumstances, and in a fuel cell system including a fuel cell, the fuel cell can be prevented from being oxidized and shifted from the power generation mode to the operation stop mode. In addition to being able to smoothly and efficiently transition from the steam reforming reaction to the partial oxidation reforming reaction, it is possible to suppress the occurrence of heat unevenness in the entire fuel cell or cell stack at the beginning of startup. It is an object of the present invention to provide a fuel cell system that is capable of performing the above.

In order to achieve this object, the present invention provides a fuel cell system including a solid electrolyte fuel cell, a power generation chamber in which a plurality of fuel cells are disposed, a power generation chamber disposed above the power generation chamber, and the A combustion chamber for burning the remaining fuel gas used in the power generation reaction by the fuel cell, a first reformer disposed above the combustion chamber and performing steam reforming of the fuel gas during power generation, and the fuel A fuel cell module having a second reformer that performs partial oxidation reforming of the fuel gas in the start mode for starting the battery system and in the operation stop mode for stopping the power generation,
The second reformer is disposed outside the vessel forming the power generation chamber and the combustion chamber, and is disposed in series with the first reformer on the downstream side of the first reformer. Thus, the present invention provides a fuel cell system through which the gas discharged from the first reformer can pass.

  According to the fuel cell system of the present invention, the second reformer that performs partial oxidation reforming of the fuel gas during the start-up mode and the operation stop mode (operation stop period) of the fuel cell system includes the power generation chamber. Since it is arranged outside the container forming the combustion chamber, the radiant heat of the second reformer does not directly affect the cells arranged in the container. Therefore, the second reformer reaches a temperature suitable for the partial oxidation reforming reaction (for example, about 300 ° C.) in a short time from the start of startup, and at this point, the temperature of the cell disposed in the vessel Even when the temperature is low, it is possible to prevent the cell from being locally heated by the radiant heat of the second reformer, and to suppress the occurrence of heat unevenness in the cell. Further, it is possible to prevent a temperature distribution in which local high-temperature portions are unevenly distributed in the entire cell stack including a plurality of cells. In the present invention, since the first reformer is disposed above the combustion chamber and can efficiently receive heat from the combustion chamber, the temperature increase of the first reformer is promoted. Can be made. Furthermore, since the second reformer is disposed outside the vessel, the catalyst can be easily exchanged.

  By the way, the second reformer arranged outside the container is less affected by the heat received from the inside of the container than in the case where the second reformer is arranged inside the container. When shifting to the shutdown mode, the temperature suitable for the partial oxidation reforming reaction has not been reached. Therefore, when shifting from the power generation mode to the shutdown mode, it is necessary to raise the temperature of the second reformer to a temperature suitable for the partial oxidation reforming reaction. In the present invention, the second reformer is disposed in series with the first reformer on the downstream side of the first reformer, and the second reformer includes the first reformer. Since the discharged high temperature gas can pass through, and the high temperature gas discharged from the first reformer can be passed through the second reformer before shifting from the power generation mode to the shutdown mode, The second reformer can be preheated to a temperature suitable for the partial oxidation reforming reaction, and the second reformer can be put on standby. For this reason, it is possible to efficiently and smoothly shift from the power generation mode to the operation stop mode, and there is no need to separately provide a heat source for raising the temperature of the second reformer, which is economical.

  Moreover, in the fuel cell system according to the present invention, the second reformer may be configured to include a pressure loss reducing unit. With this configuration, it is possible to reduce pressure loss due to fluid (fuel gas, air, water vapor, etc.) passing through the second reformer.

  Examples of the pressure loss reducing means include a bypass pipe that branches off from a pipe that connects the first reformer and the second reformer and bypasses the second reformer. Can be configured to be a flow path of the fuel gas reformed by the first reformer during the power generation mode. With this configuration, in the power generation mode, the fluid (fuel gas, air, water vapor, etc.) does not pass through the second reformer but passes through the bypass line, so that pressure loss can be further reduced. it can.

  Furthermore, in the case of a configuration in which a bypass pipe is provided as the pressure loss reducing means, the second reformer can be provided at a position farther from the container than the bypass pipe. With this configuration, before the transition from the power generation mode to the shutdown mode, the second reformer can be preheated to a temperature suitable for the partial oxidation reforming reaction. The discharged fluid (fuel gas, air, water vapor, etc.) can be prevented from rising in temperature more than necessary, and the cell can be efficiently cooled during the operation stop mode.

  In the fuel cell system according to the present invention, the second reformer includes a partial oxidation reformer for start-up that performs partial oxidation reforming of the fuel gas in the start-up mode of the fuel cell system, and the fuel cell. A configuration may also be provided that includes a partial oxidation reformer for stopping that performs partial oxidation reforming of the fuel gas during the system shutdown mode. By configuring in this manner, the partial oxidation reformer for start-up is specialized for the optimum function required in the start-up mode, and the partial oxidation-reformer for stop is in the stop mode. It is possible to make the configuration specialized for the optimum function required at the time, and the transition from the start mode to the power generation mode and the transition from the power generation mode to the operation stop mode can be performed more smoothly. In addition, only the partial oxidation reformer for stopping that is to be heated in advance to a temperature suitable for the partial oxidation reforming reaction before shifting from the power generation mode to the shutdown mode is arranged in series with the first reformer. Therefore, the pressure loss during the start-up mode can be reduced.

  In addition, in the case of the configuration in which the starting partial oxidation reformer and the stopping partial oxidation reformer are arranged, the stopping partial oxidation reformer is farther from the container than the starting partial oxidation reformer. Can be arranged in position. Here, the second reformer can prevent heat radiation as it is disposed in the vicinity of the container. Therefore, by configuring in this way, in addition to the advantages, in the start-up mode, it is possible to efficiently prevent heat release from the start-up partial oxidation reformer and promote heating in the container. In the shutdown mode, before the transition from the power generation mode to the shutdown mode, the second reformer can be preheated to a temperature suitable for the partial oxidation reforming reaction. 2 It is possible to suppress the temperature of the fluid (fuel gas, air, water vapor, etc.) discharged from the reformer from rising more than necessary, and the cell can be efficiently cooled.

  Further, in the fuel cell system according to the present invention, the fuel cell system includes a plurality of pipes that are disposed on the downstream side of the second reformer and communicates the second reformer and the container. The pipe disposed at the farthest position from the container may have a heat dissipating means. By configuring in this way, in addition to the above advantages, in the start-up mode, among the pipes that connect the second reformer and the container, the pipe that is disposed at a position close to the container A fluid (fuel gas, air, water vapor, etc.) can be passed through. Here, since the pipe disposed near the container suppresses heat radiation as described above, a high-temperature fluid (fuel gas, air, water vapor, etc.) can be supplied into the container. It is possible to heat the inside of the container efficiently. On the other hand, in the shutdown mode, fuel gas, air, water vapor, etc.) can be passed through a pipe disposed farthest from the container, so that the fluid discharged from the second reformer ( The temperature of the fuel gas, air, water vapor, etc.) can be lowered, so that the cell can be cooled efficiently.

  According to the present invention, in a fuel cell system including a fuel cell, it is possible to prevent the fuel cell from being oxidized, and to suppress the occurrence of heat unevenness in the entire fuel cell or cell stack at the beginning of startup. In addition, it is possible to provide a fuel cell system capable of smoothly and efficiently shifting from the steam reforming reaction to the partial oxidation reforming reaction when the operation is stopped.

1 is a schematic configuration diagram showing an overall configuration of a fuel cell system according to an embodiment of the present invention. It is a block diagram which shows the control structure of the fuel cell system shown in FIG. It is a graph which shows the temperature of each part in the starting mode of the fuel cell system shown in FIG. 1, and the control voltage of each part. FIG. 2 is a schematic configuration diagram more specifically showing a configuration in the vicinity of the fuel cell module of the fuel cell system shown in FIG. 1. 2 is a graph showing the temperature of each part and the flow rate of fluid supplied to each part in the operation stop mode immediately before the end of the power generation mode of the fuel cell system shown in FIG. 1. It is a schematic block diagram which shows more specifically the structure of the vicinity of the fuel cell module of the fuel cell system according to another embodiment of the present invention. It is a schematic block diagram which shows more specifically the structure of the vicinity of the fuel cell module of the fuel cell system according to another embodiment of the present invention.

  Next, a fuel cell system according to an embodiment of the present invention will be described with reference to the drawings. In addition, the Example described below is the illustration for demonstrating this invention, and this invention is not limited only to these Examples. Therefore, the present invention can be implemented in various forms without departing from the gist thereof.

  FIG. 1 is a schematic configuration diagram showing the overall configuration of a fuel cell system according to an embodiment of the present invention. As shown in FIG. 1, the fuel cell system FCS according to the present embodiment includes a fuel cell module FCM, an auxiliary unit ADU, a water storage tank WP2, and a hot water production apparatus HW.

  The fuel cell module FCM includes a fuel cell FC, a reformer RF, a control box CB, a carbon monoxide detector COD, and a combustible gas detector GD1. The fuel cell FC is a solid electrolyte fuel cell (SOFC), and includes a power generation chamber FC1 and a combustion chamber FC2. A plurality of fuel cells CE are arranged in the power generation chamber FC1. The fuel cell CE is provided with a fuel electrode and an air electrode with an electrolyte sandwiched between them. Electric power is generated by passing fuel gas to the fuel electrode side and air as oxidant gas to the air electrode side. It is configured so that a reaction can occur.

  In addition, since the fuel cell FC according to the present embodiment is a solid electrolyte fuel cell (SOFC), the material constituting the electrolyte is doped with at least one selected from rare earth elements such as Y and Sc, for example. Oxygen ion conductive oxides such as ceria doped with at least one selected from zirconia and rare earth elements, and lanthanum gallate doped with at least one selected from Sr and Mg are used.

  As a material constituting the fuel electrode, for example, a mixture of Ni and zirconia doped with at least one selected from rare earth elements such as Ca, Y, and Sc, Ni and at least one selected from rare earth elements are doped. A material such as a mixture of ceria, a mixture of Ni and lanthanum gallate doped with at least one selected from Sr, Mg, Co, Fe, and Cu is used.

  Examples of the material constituting the air electrode include lanthanum manganite doped with at least one selected from Sr and Ca, lanthanum ferrite doped with at least one selected from Sr, Co, Ni, and Cu, Sr, Fe, Ni, A material such as lanthanum cobaltite or silver doped with at least one selected from Cu is used. But the material which comprises an electrolyte, a fuel electrode, and an air electrode is not restricted to these.

  The electricity generated in the power generation chamber FC1 is taken out and used as generated power by the power extraction line EP1. The combustion chamber FC2 is a portion where the remaining fuel gas used for the power generation reaction is burned by the fuel cell CE arranged in the power generation chamber FC1. The exhaust gas generated as a result of the combustion of the fuel gas in the combustion chamber FC2 is supplied to the hot water production apparatus HW after heat exchange with the reformer RF. The exhaust gas supplied to the hot water production apparatus HW further performs heat exchange, and the tap water is heated to warm water and then discharged to the outside.

  The reformer RF is a portion that reforms a gas to be reformed, such as city gas, into fuel gas and supplies it to the power generation chamber FC1 of the fuel cell FC. As reforming modes of the gas to be reformed, there are partial oxidation reforming reaction (POX), auto thermal reforming reaction (ATR), and steam reforming reaction (SR). (Details will be described later). The reformer RF includes a reforming unit RF1 and an evaporation unit RF2. Details of the reformer RF will be described later.

  The evaporating unit RF2 is a part that evaporates pure water supplied from the auxiliary unit ADU side into water vapor and supplies the water vapor to the reforming unit RF1. The reforming unit RF1 is a part that reforms the gas to be reformed using the gas to be reformed supplied from the auxiliary unit ADU side, air, and water vapor supplied from the evaporation unit RF2 to form a fuel gas. A reforming catalyst is enclosed in the reforming unit RF1. As the reforming catalyst, those obtained by imparting Ni to the sphere surface of alumina and those imparting Ru to the sphere surface of alumina are appropriately used. In this embodiment, these reforming catalysts are spheres.

  The control box CB houses the fuel cell system control unit therein, and is provided with an operation device, a display device, and a notification device. The fuel cell system control unit, operation device, display device, and notification device will be described later.

  The carbon monoxide detector COD is a sensor for detecting whether incomplete combustion of the remaining fuel gas occurs in the combustion chamber FC2 and carbon monoxide is not generated in the fuel cell module FCM. The combustible gas detector GD1 is a sensor for detecting whether the remaining fuel gas remains unburned in the combustion chamber FC2 and so-called raw gas is not generated in the fuel cell module FCM.

  Subsequently, the auxiliary unit ADU will be described. The auxiliary device unit ADU is a unit including auxiliary devices for supplying water, reformed gas, and air to the fuel cell module FCM. The auxiliary unit ADU includes flow rate adjustment units AP1a, AP1b, and an electromagnetic valve AP2 that include an air blower and a flow rate adjustment valve as an air supply unit, and a flow rate adjustment unit FP1, which includes a fuel pump, a flow rate adjustment valve, and the like as a fuel supply unit A desulfurizer FP2, a gas cutoff valve FP4, and a gas cutoff valve FP5, a flow rate adjustment unit WP1 including a water pump and a flow rate adjustment valve as a water supply unit, and a combustible gas detector GD2 are provided.

  Air supplied from an external air supply source is not supplied to the flow rate adjustment units AP1a and AP1b when the electromagnetic valve AP2 is closed, and is supplied to the flow rate adjustment units AP1a and AP1b when the electromagnetic valve AP2 is open. The air whose flow rate is adjusted by the flow rate adjusting unit AP1a is heated as the reforming air by the heater AH1 and supplied to the mixing portion MV with the reformed gas. The air whose flow rate is adjusted by the flow rate adjusting unit AP1b is heated by the heater AH2 as power generation air and supplied to the power generation chamber FC1. The power generation air supplied to the power generation chamber FC1 is supplied to the air electrode of the fuel cell CE and used for power generation of the fuel cell CE.

  The inflow of city gas supplied from an external fuel supply source is controlled by a gas shut-off valve FP4 and a gas shut-off valve FP5 which are double solenoid valves. If both of the gas cutoff valves FP4 and FP5 are open, the city gas is supplied to the desulfurizer FP2, and if one of the gas cutoff valves FP4 and FP5 is closed, the city gas is shut off. The city gas supplied to the desulfurizer FP2 is removed from the sulfur component to become a reformed gas, and is supplied to the flow rate adjustment unit FP1. The to-be-reformed gas whose flow rate has been adjusted by the flow rate adjusting unit FP1 is supplied to the mixing unit MV with the reforming air. The gas to be reformed and the reforming air mixed in the mixing unit MV are supplied to the reformer RF.

  Tap water supplied from an external water supply source is made pure water and then stored in the water storage tank WP2. The pure water stored in the water storage tank WP2 is supplied to the reformer RF after the flow rate is adjusted by the flow rate adjustment unit WP1.

  The combustible gas detector GD2 is a system that serves as a fuel supply unit. In the gas cutoff valve FP5, the gas cutoff valve FP4, the desulfurizer FP2, and the flow rate adjustment unit FP1, gas leakage occurs and so-called raw gas is not released to the outside. It is a sensor for detecting.

  Next, the control configuration of the fuel cell system FCS of the present embodiment will be described with reference to FIG. FIG. 2 is a block diagram showing a control configuration of the fuel cell system FCS. As shown in FIG. 2, the fuel cell system FCS supplies a fuel cell module FCM, an air supply unit AP that supplies air to the fuel cell module FCM, and a reformed gas that becomes fuel gas to the fuel cell module FCM. A fuel supply unit FP, a water supply unit WP that supplies water to the fuel cell module FCM, and a power extraction unit EP that extracts power from the fuel cell module FCM are provided. The air supply unit AP, the fuel supply unit FP, the water supply unit WP, and the power extraction unit EP are housed in the auxiliary unit ADU.

  The fuel cell module FCM, the air supply unit AP, the fuel supply unit FP, the water supply unit WP, and the power extraction unit EP are controlled based on a control signal output from the fuel cell system control unit CS. The fuel cell system control unit CS includes a CPU, a memory such as a ROM and a RAM, and an interface for sending and receiving control signals and sensor signals. An operation device CS1, a display device CS2, and a notification device CS3 are attached to the fuel cell system control unit CS. The operation instruction signal input from the operation device CS1 is output to the fuel cell system control unit CS, and the fuel cell system control unit CS controls the fuel cell module FCM and the like based on the operation instruction signal. Information controlled by the fuel cell system control unit CS and predetermined warning information are output to the display device CS2 and the notification device CS3. Specific hardware configurations of the operation device CS1, the display device CS2, and the notification device CS3 are not particularly limited, and an optimal hardware configuration is selected according to a required function. As an example, hardware such as a keyboard, a mouse, and a touch panel is used as the operating device CS1. As the display device CS2, display system hardware such as a CRT display or a liquid crystal display is used. As the notification device CS3, hardware such as a speaker and a lighting device is used. The fuel cell system controller CS, the operation device CS1, the display device CS2, and the notification device CS3 are housed in a control box CB.

  Sensor signals are output to the fuel cell system controller CS from sensors provided at various locations in the fuel cell system FCS. The sensors that output signals to the fuel cell system controller CS include a reformer temperature sensor DS1, a stack temperature sensor DS2, an exhaust temperature sensor DS3, a reformer pressure sensor DS4, a water level sensor DS5, a water flow rate sensor DS6, fuel A flow rate sensor DS7, a reforming air flow rate sensor DS8, a power generation air flow rate sensor DS9, a power state detection unit DS10, a hot water storage state detection sensor DS11, a carbon monoxide detection sensor DS12, and a combustible gas detection sensor DS13 are provided.

  The reformer temperature sensor DS1 is a sensor for measuring the temperature of the reformer RF. In the present embodiment, two reformer temperature sensors DS1 are provided. The stack temperature sensor DS2 is a sensor for measuring the temperature of the fuel cell CE arranged in the power generation chamber FC1, and is arranged in the vicinity of the fuel cell stack composed of a plurality of fuel cells CE. The exhaust temperature sensor DS3 is a sensor for measuring the temperature of the exhaust gas discharged from the combustion chamber FC2, and is disposed in a path from the combustion chamber FC2 through the vicinity of the reformer RF to the hot water production apparatus HW. Yes. The reformer pressure sensor DS4 is a sensor for measuring the pressure in the reformer RF. Here, the pressure in the reformer RF is measured by a sensor, but the pressure in the portion where the fuel and water are mixed may be detected in the previous stage of the reformer RF.

  The water level sensor DS5 is a sensor for measuring the water level of the water storage tank WP2. In the present embodiment, four water level sensors DS5 are provided. The water flow rate sensor DS6 is a sensor for measuring the flow rate of pure water supplied from the auxiliary unit ADU to the fuel cell module FCM. The fuel flow rate sensor DS7 is a sensor for measuring the flow rate of the reformed gas supplied from the auxiliary unit ADU to the fuel cell module FCM. The reforming air flow rate sensor DS8 is a sensor for measuring the flow rate of the reforming air supplied from the auxiliary unit ADU to the reformer RF of the fuel cell module FCM. The power generation air flow rate sensor DS9 is a sensor for measuring the flow rate of power generation air supplied from the auxiliary unit ADU to the fuel cell module FCM.

  The power state detection unit DS10 is an assembly of sensing means, and is a part that detects the state of generated power extracted from the fuel cell module FCM. The hot water storage state detection sensor DS11 is an assembly of sensing means, and is a part that detects the hot water storage state of the hot water production apparatus HW.

  The carbon monoxide detection sensor DS12 is a sensor provided in the carbon monoxide detector COD, and is a sensor that detects the generation of carbon monoxide in the fuel cell module FCM. The combustible gas detection sensor DS13 is a sensor provided in the combustible gas detectors GD1 and GD2. In the combustible gas detector GD1, the remaining fuel gas remains unburned in the combustion chamber FC2 of the fuel cell module FCM. In other words, the combustible gas detector GD2 is a sensor that detects leakage of combustible gas in the fuel cell module FCM and the auxiliary unit ADU.

  Next, switching of various reforming reactions when the fuel cell system FCS is started (starting mode) will be described with reference to FIG. FIG. 3 is a graph showing the temperature of each part and the control voltage of each part in the startup mode of the fuel cell system FCS.

  In the start-up mode of the fuel cell system FCS in this embodiment, combustion operation, partial oxidation reforming reaction (POX), first autothermal reforming reaction (ATR1), and second autothermal reforming reaction (ATR2) And the steam reforming reaction (SR) are sequentially switched and the reforming reaction proceeds. Prior to explaining FIG. 3, each reforming reaction will be explained.

The partial oxidation reforming reaction (POX) is a reforming reaction performed by supplying a reformed gas and air to the reformer SR, and the reaction shown in the chemical reaction formula (1) proceeds.
_{C m H n + xO 2 →} aCO 2 + bCO + cH 2 (1)
Since this partial oxidation reforming reaction (POX) is an exothermic reaction, it has a high startability and is a suitable reforming reaction at the beginning of the start of the fuel cell system FCS. However, since the partial oxidation reforming reaction (POX) has a theoretically low hydrogen yield and it is difficult to control the exothermic reaction, the partial oxidation reforming reaction (POX) is used only at the beginning of startup when heat supply to the fuel cell module FCM is required. This is a preferred reforming reaction. If attention is paid only to the partial oxidation reforming reaction (POX), the space velocity is set high. For example, when the reformer RF is dividedly formed and a reformer dedicated to the partial oxidation reforming reaction (POX) is provided. In addition, the dedicated reformer can be miniaturized.

The steam reforming reaction (SR) is a reforming reaction performed by supplying the reformed gas and steam to the reformer SR, and the reaction shown in the chemical reaction formula (2) proceeds.
C _m H _n + xH ₂ O → aCO ₂ + bCO + cH ₂ (2)
The steam reforming reaction (SR) has the highest hydrogen yield and is a highly efficient reaction. However, since the steam reforming reaction (SR) is an endothermic reaction, it requires a heat source, and is a suitable reforming reaction at a stage where the temperature has risen to some extent from the beginning of the start of the fuel cell system FCS. If attention is paid only to the steam reforming reaction (SR), the space velocity is set low, so that the reformer RF tends to increase in size.

The autothermal reforming reaction (ATR) comprising the first autothermal reforming reaction (ATR1) and the second autothermal reforming reaction (ATR2) is a partial oxidation reforming reaction (POX) and a steam reforming reaction (SR). Is a reforming reaction that is performed by supplying a reforming gas, air, and steam to the reformer RF, and the reaction shown in the chemical reaction formula (3) proceeds. .
_{C m H n + xO 2 +} yH 2 O → aCO 2 + bCO + cH 2 (3)
Autothermal reforming reaction (ATR) is a combined use of partial oxidation reforming reaction (POX) and steam reforming reaction (SR) in hydrogen yield, and it is easy to balance reaction heat. POX) is a reforming reaction suitable as a reaction that connects the steam reforming reaction (SR). In the case of the present embodiment, the first autothermal reforming reaction (ATR1) closer to the partial oxidation reforming reaction (POX) is performed by supplying a small amount of water, and the water is supplied to increase after the temperature rises. Then, the second autothermal reforming reaction (ATR2) closer to the steam reforming reaction (SR) is performed later.

  Next, the startup mode of the fuel cell system FCS will be described. In FIG. 3, the horizontal axis indicates the elapsed time after the start of startup, and the left vertical axis indicates the temperature of each part. Although it is a control voltage, no special scale is provided, but the control voltage of the reforming air blower included in the flow rate adjusting unit AP1a for supplying reforming air, the flow rate adjustment for supplying power generation air Included in the control voltage of the power generation air blower included in the unit AP1b, the control voltage of the fuel pump included in the flow rate adjustment unit FP1 for supplying the reformed gas, and the flow rate adjustment unit WP1 for supplying pure water The control voltage of the water pump is shown so that the voltage increases (the supply amount increases) as it goes upward in the figure. FIG. 3 shows the temperature of the reformer RF, the stack temperature of the fuel cell CE, the temperature of the combustion chamber FC2 (estimated from the temperature of the reformer RF, etc.), and the reforming included in the flow rate adjustment unit AP1a. The control voltage of the air blower, the control voltage of the power generation air blower included in the flow rate adjustment unit AP1b, the control voltage of the fuel pump included in the flow rate adjustment unit FP2, and the control voltage of the water pump included in the flow rate adjustment unit WP1 are shown. .

  First, the flow rate adjustment unit AP1a, the electromagnetic valve AP2, the heater AH1, and the mixing unit MV are controlled so as to increase the reforming air, and air is supplied to the reformer RF. Further, the flow rate adjusting unit FP1, the gas cutoff valves FP4 and FP5, and the mixing unit MV are controlled so as to increase the supply of the reformed gas, and the reformed gas is supplied to the reformer RF. In this way, air and the gas to be reformed are supplied, and ignited by the igniter to execute the combustion operation. The combustion operation may be performed by raising the temperature of the combustion chamber FC2 and spontaneously igniting the air and the reformed gas. In the combustion chamber FC2 above the power generation chamber FC1, the fuel gas that has passed through the reformer RF and the power generation air are mixed and burned, and the temperature of the combustion chamber FC2 gradually increases.

  Subsequently, when the temperature of the reformer RF reaches about 300 ° C., the reformer RF becomes ready for partial oxidation reforming reaction operation (POX operation). The partial oxidation reforming reaction (POX) proceeds when it becomes forward or backward. Since the partial oxidation reforming reaction (POX) is an exothermic reaction, the temperature of each part increases. After a predetermined time has elapsed since the start of the partial oxidation reforming reaction (POX), the supply amount of reforming air is further increased to further advance the partial oxidation reforming reaction (POX).

  Subsequently, the first autothermal reforming reaction ATR1 is performed on the condition that the temperature of the reformer RF becomes about 600 ° C. or higher and the temperature of the cell stack constituted by the fuel cells CE exceeds about 250 ° C. To move to. In the first autothermal reforming reaction ATR1, the flow rate of reforming air supplied to the reformer RF is reduced, the flow rate of the gas to be reformed supplied to the reformer RF is maintained as it is, and a very small amount of pure water is supplied. Supply to reformer RF. The autothermal reforming reaction (ATR) is a reaction in which a partial oxidation reforming reaction (ATR) and a steam reforming reaction (SR) are mixed and is thermally balanced in the reformer RF. The reaction proceeds independently. The first autothermal reforming reaction (ATR1) is a reaction that has a relatively large amount of air and is close to the partial oxidation reforming reaction (POX), and heat generation is the dominant reaction. Note that, in the first autothermal reforming reaction (ATR1), the temperature of the cell stack constituted by the fuel cells CE is about 250 to about 400 ° C.

  Subsequently, the second autothermal reforming reaction (ATR2) is performed on the condition that the temperature of the reformer RF becomes 600 ° C. or higher and the temperature of the cell stack constituted by the fuel cell CE exceeds about 400 ° C. To move to. In the second autothermal reforming reaction (ATR2), the flow rate of reforming air supplied to the reformer RF is reduced, the flow rate of reformed gas supplied to the reformer RF is also reduced, and a small amount of pure water is modified. Supply to mass device RF. The second autothermal reforming reaction (ATR2) is a reaction close to the steam reforming reaction (SR) because of relatively little air and a lot of water, and the endothermic reaction is dominant. However, since the cell stack temperature indicating the temperature in the power generation chamber FC1 exceeds about 400 ° C., even if the endothermic reaction is dominant, there is no significant temperature drop. In addition, the temperature of the evaporation part RF2 in the second autothermal reforming reaction (ATR2) is about 100 ° C. or higher.

  Subsequently, the process proceeds to the steam reforming reaction (SR) on the condition that the temperature of the reformer RF becomes 650 ° C. or higher and the temperature of the cell stack constituted by the fuel cell CE exceeds about 600 ° C. Let In the steam reforming reaction (SR), the reforming air supplied to the reformer RF is shut off, the flow rate of the reformed gas supplied to the reformer RF is reduced, and a predetermined amount of pure water is supplied to the reformer RF. To supply. Since this steam reforming reaction (SR) is an endothermic reaction, the reaction proceeds while maintaining a heat balance by the combustion heat from the combustion chamber FC2. At this stage, since it is already the final stage of startup, the inside of the power generation chamber FC1 has been heated to a sufficiently high temperature, so that no significant temperature decrease is caused even with the endothermic reaction as a main component. Even if the steam reforming reaction (SR) proceeds, the combustion reaction continues in the combustion chamber FC2.

  As described above, the temperature in the power generation chamber FC1 gradually increases by switching the reforming process from the ignition to the progress of the combustion process. When the temperature of the power generation chamber FC1 (cell stack temperature) reaches a predetermined power generation temperature lower than the rated temperature (about 700 ° C.) at which the fuel cell module FCM is stably operated, the electric circuit including the fuel cell module FCM is changed. close. As a result, the fuel cell module FCM starts power generation, and a current flows through the circuit to supply power to the outside. Due to the power generation of the fuel cell CE, the fuel cell CE itself also generates heat, and the temperature of the fuel cell CE rises. As a result, the rated temperature for operating the fuel cell module FCM, for example, 700 to 800 ° C. is reached.

  Thereafter, in order to maintain the rated temperature, fuel gas and air in an amount larger than the amount of fuel gas and air consumed in the fuel battery cell CE are supplied, and combustion in the combustion chamber FC2 is continued. During power generation, power generation proceeds by a steam reforming reaction (SR) with high reforming efficiency. Strictly speaking, the steam reforming reaction (SR) itself is performed at about 400 to 800 ° C., but the reaction proceeds at about 500 to 700 ° C. in combination with the fuel cell CE.

  Next, the fuel cell module according to the present embodiment will be described in more detail with reference to FIG. FIG. 4 is a schematic configuration diagram more specifically showing the configuration in the vicinity of the fuel cell module according to the present embodiment.

  As shown in FIG. 4, the fuel cell module FCM according to the present embodiment includes a power generation chamber FC1, a dispersion chamber DB, a combustion chamber FC2, a steam reformer RFS, a preheater PH, an evaporation unit RF2, The partial oxidation reformer RFP is provided, and the power generation chamber FC1, the dispersion chamber DB, the combustion chamber FC2, the steam reformer RFS, the preheater PH, and the evaporation unit RF2 are accommodated in the same container C. The partial oxidation reformer RFP is disposed outside the container C.

  The dispersion chamber DB is disposed below the power generation chamber FC1. The dispersion chamber DB is for dispersing the fuel gas reformed by the reformer RF and uniformly supplying the fuel gas into the power generation chamber FC1, and the fuel gas is generated on the upper wall of the power generation chamber. A plurality of holes (not shown) for feeding into FC1 are formed through. Further, an introduction hole (not shown) for introducing a fuel gas supplied from a partial oxidation reformer RFP, which will be described in detail later, into the dispersion chamber DB is formed through the bottom surface of the dispersion chamber DB. Thereby, the fuel gas introduced from the bottom surface side (lower side) of the dispersion chamber DB is dispersed here and introduced into the power generation chamber FC1 from the bottom surface side (lower side) of the power generation chamber FC1, and FIG. 1 and FIG. As shown in FIG. 2, the fuel cell CE is installed in the power generation chamber FC1 and supplied to the fuel electrode of the fuel cell CE. A heat insulating material HI is disposed on the outer surface of the side wall and the outer surface of the bottom surface of the container C.

  As described above, the reformer RF includes the reforming unit RF1 and the evaporation unit RF2. The reforming unit RF1 further includes a steam reformer RFS that performs steam reforming of the fuel gas, and a fuel gas. And a partial oxidation reformer RFP for performing partial oxidation reforming.

  The steam reformer RFS is disposed in the upper part of the combustion chamber FC2. A preheater PH is disposed above the steam reformer RFS, and the pure water and the gas to be reformed supplied to the steam reformer RFS are supplied to the steam reformer RFS via the preheater PH. Supplied. The evaporating unit RF2 evaporates pure water supplied from the auxiliary unit ADU side into steam, and supplies the steam to the steam reformer RFS. Since this steam reformer RFS is disposed in the container C and is disposed above the combustion chamber FC2 disposed in the same container C, it uses heat generated in the combustion chamber FC2. An endothermic reaction can be performed efficiently.

  The partial oxidation reformer RFP is disposed outside the container C. The partial oxidation reformer RFP is disposed in series with the steam reformer RFS and is located downstream of the steam reformer RFS. That is, the partial oxidation reformer RFP communicates with the pipe PP1 through which the fuel gas reformed by the steam reformer RFS flows, and the fuel gas reformed by the steam reformer RFS can pass through. . The partial oxidation reformer RFP is supplied with a gas to be reformed, air, and pure water via a pipe PP1. The fuel gas reformed by the partial oxidation reformer RFP is supplied to the dispersion chamber DB from an introduction hole (not shown) formed on the bottom surface of the dispersion chamber DB via the pipe PP2. The partial oxidation reformer RFP performs partial oxidation reforming on the gas to be reformed in the start-up mode and in the operation stop mode described in detail later, but does not require water. At (POX), the fuel cell system control unit CS performs control so that pure water is not supplied to the partial oxidation reformer RFP.

  Here, as shown in FIG. 3, the partial oxidation reformer RFP reaches about 300 ° C. in about 10 minutes after ignition in the startup mode, and at this time, the temperature of the cell stack is about 100 ° C. There is a significant temperature difference between the two. At this time, if the partial oxidation reformer RFP is disposed in the container C as in the conventional fuel cell system, the fuel cell CE is locally heated by the radiant heat of the partial oxidation reformer RFP, Heat unevenness occurs in the fuel cell CE and is easily damaged. In addition, a temperature distribution in which local high temperature portions are unevenly distributed occurs in the entire cell stack, and power generation efficiency may be reduced. On the other hand, in the present embodiment, the partial oxidation reformer RFP is disposed on the outside lower side of the container C (outside of the bottom surface of the dispersion chamber DB). The fuel cell CE can be prevented from being locally heated, and the temperature distribution in which local high temperature portions are unevenly distributed can be prevented from occurring in the entire cell stack. Further, since the heat insulating material HI is disposed on the outer surface of the side wall and the bottom surface of the container C, the fuel cell CE and the entire cell stack are caused by the radiant heat of the partial oxidation reformer RFP in the start-up mode. It can be further prevented from being affected.

  Further, a branch pipe PP3 that branches from the pipe PP1 and forms a bypass pipe that bypasses the partial oxidation reformer RFP is provided downstream of the pipe PP1 from the position where the gas to be reformed, air, and pure water is supplied. It is arranged. In the present embodiment, the partial oxidation reformer RFP is disposed at a position farther from the container C than the branch pipe PP3, and its downstream end communicates (joins) with the pipe PP2. A switching valve CNG for switching the fluid flow path is disposed at a branch point between the pipe PP1 and the branch pipe PP3, and the switching valve CNG is switched based on a control signal output from the fuel cell system control unit CS. Thus, the flow path of the fluid is changed.

  Specifically, in the start-up mode, the switching valve CNG is switched so that the pipe PP1 and the partial oxidation reformer RFP are circulated, and the fuel gas reformed by the partial oxidation reformer RFP is contained in the container C. In the power generation mode, the switching valve CNG is switched so that the pipe PP1 and the branch pipe PP3 circulate, and the fuel gas reformed by the steam reformer RFS passes through the partial oxidation reformer RFP. Instead of passing, it is supplied into the container C through the branch pipe PP3. Therefore, in the power generation mode, the pressure loss can be reduced as compared with the case where the fuel gas reformed by the steam reformer RFS passes through the partial oxidation reformer RFP. That is, the branch pipe PP3 (bypass pipe) functions as a pressure loss reducing unit.

  Further, when shifting from the power generation mode to the shutdown mode, the switching valve CNG is switched so that the pipe PP1 and the partial oxidation reformer RFP are circulated as a preparatory stage before a predetermined time for performing the transition, The fuel gas reformed by the reformer RFS passes through the partial oxidation reformer RFP, and the fuel gas (steam reformed fuel gas) that has passed through the partial oxidation reformer RFP is supplied into the container C. To be. At this time, in the partial oxidation reformer RFP, the partial oxidation reforming reaction (POX) is not yet performed, and only the steam-reformed fuel gas passes, and the partial oxidation reforming is performed by the steam-reformed fuel gas. The temperature of the materializer RFP is raised to a temperature suitable for the partial oxidation reforming reaction (POX). As a result, the partial oxidation reformer RFP is ready to start the partial oxidation reforming reaction (POX) immediately when shifting from the power generation mode to the operation stop mode.

  Next, switching of various reforming reactions when the fuel cell system FCS shifts from the power generation mode to the operation stop mode will be described with reference to FIG. FIG. 5 is a graph showing the temperature of each part and the flow rate of fluid supplied to each part in the operation stop mode immediately before the end of the power generation mode of the fuel cell system FCS. In FIG. 5, the horizontal axis represents the elapsed time of the operation stop mode, and the left vertical axis represents the flow rate of fluid supplied to each part. Since it is a fluid flow rate, no special scale is given, but the flow rate increases as it goes upward in the figure.

  FIG. 5 shows the temperature of the partial oxidation reformer RFP, the stack temperature of the fuel cell CE, the flow rate of pure water supplied to the steam reformer RFS, the flow rate of fuel gas supplied to the steam reformer RFS, and partial oxidation. The flow rate of air supplied to the reformer RFP, the flow rate of pure water supplied to the partial oxidation reformer RFP, the flow rate of fuel gas supplied to the partial oxidation reformer RFP, and the amount of power generation current of the fuel cell FC are shown. Yes.

  First, as a preparatory step before the transition from the power generation mode to the shutdown mode, the switching valve CNG is switched so that the pipe PP1 and the partial oxidation reformer RFP are circulated a predetermined time before the end of the power generation mode, The fuel gas reformed by the mass device RFS is passed through the partial oxidation reformer RFP. By this operation, the temperature of the partial oxidation reformer RFP rises from about 300 ° C. to about 500 ° C. as the high-temperature fuel gas reformed by the steam reformer RFS passes as shown in FIG. As a result, the partial oxidation reforming reaction (POX) can be started immediately.

  Next, in order to shift from the steam reforming reaction (SR) to the reaction including the partial oxidation reforming reaction (POX), the flow rate adjustment unit WP1 is controlled to decrease the pure water flow rate to the steam reformer RFS. Further, the flow rate adjusting unit FP1, the gas shut-off valves FP4 and FP5, and the mixing unit MV are controlled so as to reduce the flow rate of the reformed gas supplied to the steam reformer RFS. Further, the flow rate adjustment unit AP1 is controlled so as to reduce the flow rate of the power generation air supplied to the power generation chamber FC1. The current generated by the fuel cell FC decreases as the pure water flow rate and the fuel gas flow rate to the steam reformer RFS decrease. In the preparation stage, the partial oxidation reformer RFP is about 500 ° C. At this point, the fuel cell CE is at a higher temperature than the partial oxidation reformer RFP. The temperature of the mass device RFP does not locally increase the temperature of the fuel cell CE. Further, as described above, the partial oxidation reformer RFP is disposed at a position farther from the container C than the branch pipe PP3, so that the fluid discharged from the partial oxidation reformer RFP (fuel gas, air, It is possible to suppress the temperature of water vapor or the like from rising more than necessary, and the fuel cell can be efficiently cooled.

  Next, the pure water flow rate and the fuel gas flow rate to the steam reformer RFS have reached a predetermined amount. In this state, a predetermined time has elapsed, and the flow rate of power generation air supplied to the power generation chamber FC1 has reached a predetermined amount. As a condition, a minute amount of pure water is supplied to the partial oxidation reformer RFP, and then a predetermined amount of fuel gas and reforming air are supplied to perform a reaction including a partial oxidation reforming reaction (POX). As shown in FIG. 5, at the initial stage of supplying pure water, fuel gas, and reforming air to the partial oxidation reformer RFP, the supply of pure water and fuel gas to the steam reformer RFS is continued. However, the supply of pure water and fuel gas to the steam reformer RFS is stopped when the reaction including the partial oxidation reforming reaction (POX) proceeds to some extent. At the time of the reaction including the partial oxidation reforming reaction (POX), the power generation air of about 300 ° C. is supplied to the power generation chamber FC1, so that the temperature of the reaction including the partial oxidation reforming reaction (POX) is increased to about 950 ° C. The heated cell stack is mainly cooled by the power generation air, and the reaction including the partial oxidation reforming reaction (POX) is performed until the cell stack temperature reaches about 300 ° C. Further, the oxidation of the fuel cell CE can be prevented by causing the reaction including the partial oxidation reforming reaction (POX) to occur in the cell oxidation temperature region in which the fuel cell CE is easily oxidized.

  On condition that the temperature of the cell stack reaches about 300 ° C., the supply of air to the partial oxidation reformer RFP is stopped, and then the supply of fuel gas and the supply of pure water are sequentially stopped. With this operation, the cell stack temperature gradually decreases, and the temperature of the partial oxidation reformer RFP decreases from the time when the supply of the fuel gas is stopped to 100 ° C. or less. After a predetermined time has elapsed after the temperature of the cell stack and the temperature of the partial oxidation reformer RFP have become 100 ° C. or less, the supply of power generation air is stopped.

  In this embodiment, the switching valve CNG is switched during the power generation mode. However, the present invention is not limited to this, and the switching valve CNG may be switched immediately after the power generation ends. Immediately after the end of power generation, the heat in the combustion chamber FC2 is still high, and the steam reformer RFS can receive the heat, so that the temperature of the partial oxidation reformer RFP is set to the partial oxidation reforming reaction (POX) as in the above embodiment. The temperature can be raised to a temperature suitable for the temperature. Moreover, in that case, it can contribute to the oxidation prevention of the fuel cell at the time of an emergency stop further.

  In addition, although the present Example demonstrated the case where the downstream side of piping PP1 was branched and the branch pipe PP3 (bypass pipe line) which bypasses the partial oxidation reformer RFP was arrange | positioned, not only this but partial, If the oxidation reformer RFP is disposed outside the vessel C and disposed downstream of the steam reformer RFS in series with the steam reformer RFS, the branch pipe PP3 is not necessarily disposed. You don't have to.

  In addition, as shown in FIG. 6, for example, the fuel cell system FCS according to the present invention is configured so that a partial oxidation reformer RFP disposed outside the container C is subjected to a partial oxidation reforming reaction (POX) in the start-up mode. The partial oxidation reformer RFP1 for starting and the partial oxidation reformer RFP2 for stopping performing the partial oxidation reforming reaction (POX) in the operation stop mode. In the configuration shown in FIG. 6, since the partial oxidation reformer RFP2 for stoppage is disposed in series with the steam reformer RFS via the pipe PP1, before the transition from the power generation mode to the shutdown mode, the steam The fuel gas heated by the reformer RFS is introduced into the partial oxidation reformer RFP2 for stopping, and the partial oxidation reformer RFP2 for stopping is heated in advance to a temperature suitable for the partial oxidation reforming reaction. Thus, the power generation mode can be efficiently and smoothly shifted to the operation stop mode. Note that air, fuel gas, and pure water are supplied to the starting partial oxidation reformer RFP1 through the pipe PP4.

  Further, in the configuration shown in FIG. 6, the partial oxidation reformer RFP2 for stopping is disposed at a position farther from the container C than the partial oxidation reformer RFP1 for activation. With this configuration, in the start-up mode, heat release from the start-up partial oxidation reformer RFP1 is efficiently prevented to promote heating in the container C, and in the operation stop mode, in the container C, Since a fluid having a temperature lower than that in the start mode can be supplied, the fuel cell CE can be cooled more efficiently.

  Further, the fuel cell system FCS according to the present invention includes, for example, a plurality (FIG. 7) of communicating the partial oxidation reformer RFP and the container C on the downstream side of the partial oxidation reformer RFP as shown in FIG. 2) pipes PP5 and PP6 are arranged, and the switching valve CNG is switched to thereby provide a flow path that reaches the inside of the container C from the partial oxidation reformer RFP through the pipe PP5, and a partial oxidation modification. You may make it select the flow path which reaches | attains the container C through piping PP6 from the quality device RFP. In the case of the configuration shown in FIG. 7, since the pipe PP6 is disposed at a position farther from the container C than the pipe PP5, the length of the flow path of the pipe PP6 is longer than the length of the flow path of the pipe PP5. Therefore, the pipe PP6 has a configuration in which heat is radiated more easily than the pipe PP5, that is, the pipe PP6 is provided with a heat radiating means. Therefore, in the start-up mode in which heating in the container C is desired to be promoted, the fuel discharged from the partial oxidation reformer RFP is supplied to the container C through the pipe PP5 with little heat dissipation. In the operation stop mode in which the switching valve CNG is switched by the battery system control unit CS to efficiently cool the fuel cell CE, the fluid discharged from the partial oxidation reformer RFP is dissipated through the pipe PP6 and is contained in the container C. By switching the switching valve CNG by the fuel cell system controller CS, the efficiency of the fuel cell system FCS can be improved.

  In the configuration shown in FIG. 7, the heat radiation amount from the pipe PP6 is increased by making the length of the pipe PP6 longer than the pipe PP5, and this is used as the heat radiation means. For example, other than the pipe disposed farthest from the container C, such as increasing the thermal conductivity of the material constituting the pipe farthest from the container C (the pipe PP6 in FIG. 7). A heat dissipating means may be provided.

ADU: Auxiliary unit C: Container CE: Fuel cell CS: Fuel cell system controller DB: Dispersion chamber FC: Fuel cell FC1: Power generation chamber FC2: Combustion chamber FCM: Fuel cell module FCS: Fuel cell system FP: Fuel supply Part FP4, FP5, FP6, FP7: Gas shut-off valve HI: Heat insulating material POX: Partial oxidation reforming reaction PP1 to PP6: Piping RF: Reformer RF1: Reforming part RF2: Evaporating part RFP: Partial oxidation reformer RFP1 : Partial oxidation reformer for activation RFP2: Partial oxidation reformer for stoppage RFS: Steam reformer SR: Steam reforming reaction

Claims (7)

A fuel cell system including a solid electrolyte fuel cell,
A power generation chamber in which a plurality of fuel cells are arranged, a combustion chamber disposed above the power generation chamber and burning residual fuel gas used for a power generation reaction by the fuel cell, and above the combustion chamber And a partial reforming of the fuel gas in the start mode for starting the fuel cell system and in the stop mode for stopping the power generation. A fuel cell module having a second reformer for performing reforming,
The second reformer is disposed outside the vessel forming the power generation chamber and the combustion chamber, and is disposed in series with the first reformer on the downstream side of the first reformer. A fuel cell system through which the gas discharged from the first reformer can pass.   The fuel cell system according to claim 1, wherein the second reformer includes pressure loss reducing means. The pressure loss reducing means is a bypass pipe that is branched from a pipe communicating the first reformer and the second reformer, and bypasses the second reformer,
3. The fuel cell system according to claim 2, wherein the bypass pipe is a flow path of the fuel gas reformed by the first reformer in the power generation mode.   The fuel cell system according to claim 3, wherein the second reformer is disposed at a position farther from the container than the bypass conduit.   The second reformer includes a startup partial oxidation reformer that performs partial oxidation reforming of the fuel gas during a startup mode of the fuel cell system, and the fuel gas during a shutdown mode of the fuel cell system. A fuel cell system according to claim 1, further comprising: a partial oxidation reformer for stopping that performs partial oxidation reforming.   The fuel cell system according to claim 5, wherein the partial oxidation reformer for stop is disposed at a position farther from the container than the partial oxidation reformer for start-up.   A plurality of pipes are provided on the downstream side of the second reformer and communicate with the second reformer and the container, and are arranged at a position farthest from the container among the plurality of pipes. The fuel cell system according to claim 1, wherein the pipe is provided with a heat dissipating means.

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