JP2014022232A - Solid oxide fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid oxide fuel cell capable of extending a service life of a reformer by suppressing thermal runaway.SOLUTION: A solid oxide fuel cell (1) comprises: a fuel cell module (2) provided with a plurality of fuel cell units (16); a reforming unit (20b) which is disposed above the plurality of fuel cell units and generates hydrogen by partial oxidation reforming reaction and steam-reforming reaction; an evaporation chamber (20a) disposed adjacent to the reforming unit; a combustion chamber (18) which heats the evaporation chamber; means for supplying a fuel; means for supplying an oxidant gas for reformation; means for supplying water; means for supplying an oxidant gas for power generation; and control means (110) for increasing the temperatures of the fuel cell units to a temperature at which power can be generated in a fuel cell module starting step. The control means controls the means for supplying an oxidant gas for reformation and the means for supplying water so that partial oxidation reforming reaction does not occur alone during all periods of the starting step.

Description

  The present invention relates to a solid oxide fuel cell, and more particularly to a solid oxide fuel cell that generates electric power by reacting a fuel and an oxidant gas for power generation.

  Japanese Unexamined Patent Application Publication No. 2004-319420 (Patent Document 1) describes a fuel cell and an operation method thereof. In the fuel cell described here, in the start-up process, a plurality of processes for reforming the fuel in the reformer, that is, a partial oxidation reforming reaction process (POX process), an autothermal reforming reaction process (ATR process) ), Through the steam reforming reaction step (SR step), the process proceeds to the power generation step.

  Here, in the fuel cell described in Patent Document 1, a reformer is disposed in the fuel cell module, and this reformer is supplied to each fuel cell and generates power in each fuel cell. The remaining fuel gas (off gas) that is not used is heated by burning at the upper end of each fuel cell. In the present specification, a fuel cell of a type that uses such off-gas combustion heat to heat the reformer to a temperature capable of reforming is called an “off-gas combustion cell burner type” fuel cell. .

  In such an off-gas combustion cell burner type fuel cell, at the time of start-up, the reformer at room temperature burns off-gas (since no power is generated during start-up, all supplied fuel becomes off-gas). To heat. When the temperature of the catalyst in the reformer rises to about 300 ° C. by this heating, a partial oxidation reforming reaction in which the fuel and the reforming air react occurs in the reformer (POX process). . Since the partial oxidation reforming reaction is an exothermic reaction, when the partial oxidation reforming reaction occurs in the reformer, the reformer is strongly heated by the reaction heat and the combustion heat of the off gas.

  When the temperature of the reformer further rises due to this heating, reforming steam is supplied into the reformer, and a steam reforming reaction in which the fuel and steam react is generated in the reformer. This steam reforming reaction is a reaction that can generate hydrogen more efficiently than the partial oxidation reforming reaction, but does not occur unless the temperature of the catalyst in the reformer rises to about 600 ° C. In addition, since the steam reforming reaction is an endothermic reaction, unless the temperature in the reformer and the fuel cell module is sufficiently increased, the temperature of the catalyst is rapidly decreased, and stable steam reforming can be performed. Can not. Therefore, in the off-gas combustion cell burner type fuel cell, after the POX process is performed, reforming air and steam are supplied to the reformer, and the partial oxidation reforming reaction and the steam reforming reaction are performed in the reformer. Are simultaneously generated (ATR process). In this ATR process, the temperature inside the reformer and the fuel cell module is raised while maintaining an appropriate balance between heat generation due to the partial oxidation reforming reaction, heat absorption due to the steam reforming reaction, and off-gas combustion heat.

  When the temperature in the reformer and the fuel cell module is sufficiently increased by the ATR process, the supply of reforming air is stopped and only the steam reforming reaction occurs in the reformer (SR process). ). Thereafter, when the temperature of each fuel cell is raised to a temperature at which power generation is possible by the SR process, the fuel cell shifts to the power generation process, and hydrogen is generated exclusively by the steam reforming reaction in the power generation process.

  Thus, in an off-gas combustion cell burner type fuel cell that does not have a dedicated heating means for the reformer, it is modified by a POX process that uses a partial oxidation reforming reaction that occurs at a relatively low temperature in the initial stage of the start-up process. After the mass vessel is rapidly heated from room temperature, reforming using the steam reforming reaction (ATR process, SR process) is performed.

JP 2004-319420 A

  However, since the partial oxidation reforming reaction in the POX process generates a large amount of heat, when the partial oxidation reforming reaction occurs in the reformer, the temperature of the surrounding catalyst rapidly increases. When the temperature of the catalyst rises in this way, the partial oxidation reforming reaction is further promoted in that portion, and the high temperature portion is further heated. For this reason, in the POX process, there exists a problem that the inside of a reformer tends to fall into a thermal runaway state. When such a thermal runaway occurs, the reformer temperature rises locally and excessively before the temperature of the entire reformer rises sufficiently. If such a state continues for a long time, the temperature of the reformer rises excessively locally and the reforming catalyst deteriorates, so that the service life of the reformer is shortened or the reformer is damaged. There is a problem that it may be done.

  Therefore, the present invention provides a solid oxide that can extend the service life of the reformer or prevent damage to the reformer by rapidly increasing the temperature in the reformer while suppressing thermal runaway. The object is to provide a physical fuel cell.

  In order to solve the above-described problems, the present invention provides a solid oxide of an off-gas combustion cell burner system in which the fuel supplied to the fuel cell flows out from one end, and the reformed portion is heated by burning the out-flowing off gas. A fuel cell module comprising a plurality of fuel cell units each having a fuel electrode formed in an internal passage through which fuel passes, and above the plurality of fuel cell units in the fuel cell module A reformer that generates hydrogen through a partial oxidation reforming reaction by chemically reacting fuel and reforming oxidant gas, and by a steam reforming reaction by chemically reacting fuel and reforming steam Disposed above the plurality of fuel cell units, adjacent to the reforming unit, and disposed in the fuel cell module to evaporate the supplied water. The fuel that has passed through the internal passage is combusted at the upper end of each fuel cell unit, and the reforming section reforms by supplying fuel to the combustion chamber that heats the upper reforming section and evaporation chamber and the reforming section. Supply means for sending the fuel to each fuel cell unit, reforming oxidant gas supply means for supplying reforming oxidant gas to the reforming section, and reforming water to the evaporation chamber Water supply means for generating, oxidant gas supply means for power generation for supplying oxidant gas for power generation to the oxidant gas electrodes of a plurality of fuel cell units, and fuel supply means, reforming in the startup process of the fuel cell module Control for generating a partial oxidation reforming reaction and a steam reforming reaction in the reforming section by controlling the oxidant gas supplying means and the water supplying means, and raising the temperature of the plurality of fuel cell units to a temperature capable of generating power. And the control means includes: In the entire period of the dynamic process is characterized by controlling reforming oxidant gas supply means, and a water supply means as a partial oxidation reforming reaction in the reforming portion does not occur by itself.

  In the present invention configured as described above, the fuel supply means and the reforming oxidant gas supply means supply the fuel and the reforming oxidant gas to the reforming section. The water supply means supplies water for reforming to an evaporation chamber disposed adjacent to the reforming unit. The fuel reformed by the reforming unit is supplied to a plurality of fuel cell units provided in the fuel cell module. The fuel that has passed through the internal passage in which the fuel electrodes of the plurality of fuel cell units are formed is burned at the upper end of each fuel cell unit and heats the upper reforming section and the evaporation chamber. The control means controls the fuel supply means, the reforming oxidant gas supply means, and the water supply means in the starting process of the fuel cell module to generate a partial oxidation reforming reaction and a steam reforming reaction in the reforming section. The temperature of the plurality of fuel cell units is raised to a temperature at which power generation is possible. Further, the control means controls the reforming oxidant gas supply means and the water supply means so that the partial oxidation reforming reaction does not occur independently in the reforming section during the entire period of the startup process.

  Conventionally, a solid oxide fuel cell of an off-gas combustion cell burner type in which the fuel (off-gas) that has passed through each fuel cell unit is burned and the reforming part is heated by this combustion heat is partially oxidized in the start-up process. A reforming reaction (POX process), an autothermal reforming reaction (ATR process), and a steam reforming reaction (SR process) are sequentially generated in the reforming section to raise the temperature of the fuel cell unit. Here, since the partial oxidation reforming reaction occurs at a relatively low temperature and is an exothermic reaction, the inside of the fuel cell module can be strongly heated. For this reason, the POX process in which the partial oxidation reforming reaction is independently generated is an indispensable process in the initial stage of heating the fuel cell unit from room temperature. However, if a partial oxidation reforming reaction occurs alone in the reforming section, it is likely to cause thermal runaway due to rapid heating, and the catalyst in the reforming section is deteriorated, which shortens the service life of the reforming section. It was. In order to make it possible to generate steam for steam reforming at the initial stage of the start-up process, the inventor of the present invention is able to generate steam for steam reforming at the initial stage of the start-up process. An evaporation chamber for generating water vapor was disposed above the plurality of fuel cell units and was disposed adjacent to the reforming unit. As a result, the temperature of the evaporation chamber can be rapidly increased after the start-up process is started. In the present invention, by adopting such a configuration, by appropriately controlling the reforming oxidant gas supply means and the water supply means, the partial oxidation reforming reaction is not generated alone in the reforming section. In addition, the temperature in the fuel cell module was successfully raised to a temperature at which power generation was possible. Thereby, the thermal runaway of the reforming part was prevented, and the above technical problem was solved.

  In the present invention, preferably, the control means includes an ATR process in which a partial oxidation reforming reaction and a steam reforming reaction occur simultaneously in the reforming section, and a steam reforming process in the reforming section as a fuel reforming process in the reforming section. Only the SR process in which only the quality reaction occurs is executed.

  According to the present invention configured as described above, only the ATR process in which the partial oxidation reforming reaction and the steam reforming reaction occur simultaneously and the SR process in which only the steam reforming reaction occurs are executed in the reforming unit. Therefore, the partial oxidation reforming reaction, which is an exothermic reaction, does not occur alone in the reforming section, and deterioration and damage of the reforming section due to thermal runaway of the reforming reaction can be prevented.

In the present invention, preferably, the control means includes a reforming oxidant gas in a reforming oxidant gas in which the supply amount of the reforming oxidant gas is capable of reforming fuel by only a partial oxidation reforming reaction in the reforming unit. The reforming oxidant gas supply means is controlled so that the ratio of oxygen O ₂ is always smaller than the ratio O ₂ /C=0.4 of the oxygen O ₂ and carbon C in the fuel.
According to the present invention thus configured, the ratio of oxygen O ₂ is always higher than the ratio O ₂ /C=0.4 of oxygen O ₂ in the reforming oxidant gas and carbon C in the fuel. Since the reforming oxidant gas supply means is controlled so as to decrease, oxygen O ₂ is insufficient in order to partially oxidize and reform the entire amount of supplied fuel, and a steam reforming reaction is always induced and improved. The quality part can be reliably protected.

  In the present invention, preferably, the control means executes the ATR process in a plurality of stages, and controls the water supply means so that the amount of water supply is minimized in the initial stage of the ATR process.

  According to the present invention configured as described above, the ATR process is executed in a plurality of stages, and in the initial stage of the ATR process, the water supply amount is minimized, so that the start-up process in which the temperature of the reforming unit is low Therefore, the endothermic heat generated by the steam reforming reaction is suppressed, and the temperature of the reforming section can be reliably increased.

  In the present invention, preferably, the control means supplies water before the temperature of the reforming section reaches a temperature at which the partial oxidation reforming reaction occurs so that the partial oxidation reforming reaction does not occur alone in the reforming section. Start the water supply by means.

  According to the present invention configured as described above, since the supply of water by the water supply unit is started before the temperature of the reforming unit reaches the temperature at which the partial oxidation reforming reaction occurs, Is converted into water vapor in the evaporation chamber, and when the temperature reaches the temperature at which the partial oxidation reforming reaction occurs, the water vapor can be reliably supplied to the reforming section.

  In the present invention, preferably, the control means ignites the fuel that has passed through the internal passage of each fuel cell unit, and then before the temperature of the reforming section reaches the temperature at which the partial oxidation reforming reaction occurs. The supply of water by the supply means is started.

  In an off-gas combustion cell burner type solid oxide fuel cell, generally, even if ignition is performed, the off-gas is not immediately ignited, and it may take time to complete the ignition. If the supply of water is started before ignition, a large amount of water is stored without being evaporated in the evaporation chamber when the time required for ignition becomes long. When a large amount of water is stored in the evaporation chamber, it takes a long time until the water starts to evaporate, and the supply of water vapor is delayed. In addition, when a large amount of stored water evaporates in a short time, a steam reforming reaction may occur abruptly in the reforming section, and the endotherm may cause a temperature drop in the reforming section. According to the present invention configured as described above, since the supply of water is started after being ignited, the delay in the supply of steam and the occurrence of a rapid steam reforming reaction are avoided, and the partial oxidation reforming reaction is prevented. A single occurrence and a temperature drop in the reforming section are reliably prevented.

  In the present invention, preferably, the control means operates the water supply means before executing the ignition process for igniting the fuel that has passed through the internal passages of each fuel cell unit, and stops the water supply means during the ignition process. At the same time, water supply by the water supply means is started after ignition.

  Generally, at the start of the start-up process, the conduit that guides water from the water supply means to the evaporation chamber is filled with air. For this reason, when it is necessary to supply water to the evaporation chamber, a time lag occurs until water is actually supplied to the evaporation chamber even if the water supply means is operated. According to the present invention configured as described above, since the water supply means is operated before the ignition step is performed, the air in the pipe leading water to the evaporation chamber can be purged in advance, The time lag of water supply when the water supply means is operated later can be shortened, and water can be supplied into the evaporation chamber at an appropriate time.

  In the present invention, preferably, the control means increases the water supply amount while changing from the ATR1 process which is the initial stage of the ATR process to the ATR2 process which is the next stage, while the oxidizing gas for reforming. Maintain a constant supply.

  According to the present invention configured as described above, the supply amount of the oxidizing gas for reforming is maintained constant when shifting from the ATR1 process to the ATR2 process. While maintaining the amount, the steam reforming ratio is increased, and the risk of carbon deposition in the reforming section and the temperature drop in the reforming section can be suppressed.

In the present invention, preferably, the control means maintains the fuel supply amount constant when shifting from the ATR1 process to the ATR2 process.
According to the present invention configured as described above, since the fuel supply amount is kept constant when the process shifts from the ATR1 process to the ATR2 process, the reforming reaction becomes unstable when the temperature of the reforming section is low. Can be prevented, and the temperature of the reforming section can be raised stably.

  In the present invention, preferably, the control means is configured to execute the ATR3 step after the ATR2 step, and when shifting from the ATR2 step to the ATR3 step, the fuel supply amount and the reforming oxidant gas supply amount. While maintaining a constant water supply.

  According to the present invention configured as described above, the fuel supply amount and the reforming oxidant gas supply amount are changed at the time of transition from the ATR2 process in which the temperature of the reforming portion is relatively increased. The risk of destabilization can be minimized.

  According to the solid oxide fuel cell of the present invention, the temperature inside the reformer is rapidly increased while suppressing thermal runaway, thereby extending the service life of the reformer or causing damage to the reformer. Can be prevented.

1 is an overall configuration diagram showing a fuel cell device according to an embodiment of the present invention. It is front sectional drawing which shows the fuel cell module of the fuel cell apparatus by one Embodiment of this invention. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. It is (a) partial sectional view and (b) cross-sectional view which show the fuel cell unit of the fuel cell apparatus by one Embodiment of this invention. It is a perspective view which shows the fuel cell stack of the fuel cell apparatus by one Embodiment of this invention. 1 is a block diagram showing a fuel cell device according to an embodiment of the present invention. 1 is a perspective view of a reformer of a fuel cell device according to an embodiment of the present invention. FIG. 5 is a perspective view showing the inside of the reformer with the top plate removed in the fuel cell device according to an embodiment of the present invention. 1 is a cross-sectional plan view showing a flow of fuel inside a reformer in a fuel cell device according to an embodiment of the present invention. 1 is a perspective view showing a metal case and an air heat exchanger housed in a housing in a fuel cell device according to an embodiment of the present invention. In the fuel cell device by one Embodiment of this invention, it is sectional drawing which shows the positional relationship of the heat insulating material for heat exchangers, and an evaporation part. 5 is a control flowchart in a startup process in a fuel cell device according to an embodiment of the present invention. 4 is a table showing the supply amount of fuel, reforming air, water, and power generation air in each stage of the startup process in the fuel cell device according to the embodiment of the present invention. 4 is a time chart showing an example of each supply amount of fuel and the like in the start-up process and the temperature of each part in the fuel cell device according to the embodiment of the present invention. It is sectional drawing which shows the heat insulation layer for evaporation chamber temperature rising in the fuel cell apparatus by the modification of this invention.

Next, a solid oxide fuel cell (SOFC) according to an embodiment of the present invention will be described with reference to the accompanying drawings.
FIG. 1 is an overall configuration diagram showing a solid oxide fuel cell (SOFC) according to an embodiment of the present invention. As shown in FIG. 1, a solid oxide fuel cell (SOFC) 1 according to an embodiment of the present invention includes a fuel cell module 2 and an auxiliary unit 4.

  The fuel cell module 2 includes a housing 6, and a case 8 constituting a sealed space surrounded by a heat insulating material 7 that is an outer heat insulating material is accommodated in the housing 6. A fuel cell assembly 12 that performs a power generation reaction with fuel and an oxidant (air) is disposed in a power generation chamber 10 that is a lower portion inside the case 8. The fuel cell assembly 12 includes ten fuel cell stacks 14 (see FIG. 5), and the fuel cell stack 14 includes 16 fuel cell unit 16 (see FIG. 4). Yes. Thus, the fuel cell assembly 12 has 160 fuel cell units 16, and all of these fuel cell units 16 are connected in series.

A combustion chamber 18 is formed above the above-described power generation chamber 10 inside the case 8 of the fuel cell module 2. In this combustion chamber 18, residual fuel and residual oxidant (air) that have not been used for the power generation reaction. Burns and produces exhaust gas.
Further, a reformer 20 for reforming the fuel is disposed above the combustion chamber 18, and the reformer 20 is heated to a temperature at which a reforming reaction can be performed by the combustion heat of the residual gas. Yes. Further, an air heat exchanger 22 is disposed above the reformer 20 to heat the air by receiving heat from the reformer 20 and suppress a temperature drop of the reformer 20.

  Next, the auxiliary unit 4 stores a pure water tank 26 that stores water from a water supply source 24 such as tap water and uses the filter to obtain pure water, and a water flow rate that adjusts the flow rate of the water supplied from the water storage tank. An adjustment unit 28 (such as a “water pump” driven by a motor) is provided. In addition, the auxiliary unit 4 adjusts the flow rate of the fuel gas, the gas shutoff valve 32 for shutting off the fuel supplied from the fuel supply source 30 such as city gas, the desulfurizer 36 for removing sulfur from the fuel gas, A fuel flow rate adjustment unit 38 (such as a “fuel pump” driven by a motor) is provided. Further, the auxiliary unit 4 includes an electromagnetic valve 42 that shuts off air that is an oxidant supplied from the air supply source 40, a reforming air flow rate adjusting unit 44 that adjusts the flow rate of air, and a power generation air flow rate adjusting unit. 45 (such as an “air blower” driven by a motor), a first heater 46 for heating the reforming air supplied to the reformer 20, and a second for heating the power generating air supplied to the power generation chamber And a heater 48. The first heater 46 and the second heater 48 are provided in order to efficiently raise the temperature at startup, but may be omitted.

Next, a hot water production apparatus 50 to which exhaust gas is supplied is connected to the fuel cell module 2. The hot water production apparatus 50 is supplied with tap water from the water supply source 24, and the tap water is heated by the heat of the exhaust gas and supplied to a hot water storage tank of an external hot water heater (not shown).
The fuel cell module 2 is provided with a control box 52 for controlling the amount of fuel gas supplied and the like.
Furthermore, the fuel cell module 2 is connected to an inverter 54 that is a power extraction unit (power conversion unit) for supplying the power generated by the fuel cell module to the outside.

Next, the internal structure of a solid oxide fuel cell (SOFC) fuel cell module according to an embodiment of the present invention will be described with reference to FIGS. FIG. 2 is a side sectional view showing a solid oxide fuel cell (SOFC) fuel cell module according to an embodiment of the present invention, and FIG. 3 is a sectional view taken along line III-III in FIG. .
As shown in FIGS. 2 and 3, the sealed case 8 in the housing 6 of the fuel cell module 2 includes the fuel cell assembly 12, the reformer 20, and the air in order from the bottom as described above. A heat exchanger 22 is arranged.

  The reformer 20 is provided with a pure water introduction pipe 60 for introducing pure water and a reformed gas introduction pipe 62 for introducing reformed fuel gas and reforming air to the upstream end side thereof. In the reformer 20, an evaporator 20a and a reformer 20b are formed in this order from the upstream side, and the evaporator 20a and the reformer 20b are filled with a reforming catalyst. The fuel gas and air mixed with the steam (pure water) introduced into the reformer 20 are reformed by the reforming catalyst filled in the reformer 20. As the reforming catalyst, a catalyst obtained by imparting nickel to the alumina sphere surface or a catalyst obtained by imparting ruthenium to the alumina sphere surface is appropriately used.

  A fuel gas supply pipe 64 is connected to the downstream end side of the reformer 20, and the fuel gas supply pipe 64 extends downward and further in an manifold 66 formed below the fuel cell assembly 12. It extends horizontally. A plurality of fuel supply holes 64 b are formed in the lower surface of the horizontal portion 64 a of the fuel gas supply pipe 64, and the reformed fuel gas is supplied into the manifold 66 from the fuel supply holes 64 b.

  A lower support plate 68 having a through hole for supporting the fuel cell stack 14 described above is attached above the manifold 66, and the fuel gas in the manifold 66 flows into the fuel cell unit 16. Supplied.

Next, an air heat exchanger 22 is provided above the reformer 20.
Further, as shown in FIG. 2, an ignition device 83 for starting combustion of fuel gas and air is provided in the combustion chamber 18.

Next, the fuel cell unit 16 will be described with reference to FIG. FIG. 4A is a partial cross-sectional view showing a fuel cell unit of a solid oxide fuel cell (SOFC) according to an embodiment of the present invention. FIG. 4B is a cross-sectional view of the fuel cell unit.
As shown in FIG. 4A, the fuel cell unit 16 includes a fuel cell 84 and inner electrode terminals 86 respectively connected to the vertical ends of the fuel cell 84.
The fuel cell 84 is a tubular structure extending in the vertical direction, and includes a cylindrical inner electrode layer 90 that forms a fuel gas flow path 88 that is an internal passage therein, a cylindrical outer electrode layer 92, and an inner electrode. An electrolyte layer 94 is provided between the layer 90 and the outer electrode layer 92. The inner electrode layer 90 is a fuel electrode through which fuel gas passes and becomes a (−) electrode, while the outer electrode layer 92 is an air electrode in contact with air and becomes a (+) electrode.

  Since the inner electrode terminal 86 attached to the upper end side and the lower end side of the fuel cell 16 has the same structure, the inner electrode terminal 86 attached to the upper end side will be specifically described here. The upper portion 90 a of the inner electrode layer 90 includes an outer peripheral surface 90 b and an upper end surface 90 c exposed to the electrolyte layer 94 and the outer electrode layer 92. The inner electrode terminal 86 is connected to the outer peripheral surface 90b of the inner electrode layer 90 through a conductive sealing material 96, and is further in direct contact with the upper end surface 90c of the inner electrode layer 90, thereby Electrically connected. A fuel gas passage 98 communicating with the fuel gas passage 88 of the inner electrode layer 90 is formed at the center of the inner electrode terminal 86.

  The inner electrode layer 90 is, for example, a mixture of NiO and zirconia doped with at least one selected from rare earth elements such as Ca, Y, and Sc, NiO and ceria doped with at least one selected from rare earth elements. It can be formed from at least one of a mixture, a mixture of NiO and a lanthanum garade doped with at least one selected from Sr, Mg, Co, Fe, and Cu.

  The electrolyte layer 94 is, for example, zirconia doped with at least one selected from rare earth elements such as Y and Sc, ceria doped with at least one selected from rare earth elements, lanthanum gallate doped with at least one selected from Sr and Mg, It can be formed from at least one of the following.

  The outer electrode layer 92 includes, for example, 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 and Cu. It can be formed from at least one of lanthanum cobaltite doped with at least one selected from the group consisting of silver and silver.

Next, the structure of the fuel cell 84 will be described in detail with reference to FIG.
As shown in FIG. 4B, the inner electrode layer 90 includes a first fuel electrode 90d and a second fuel electrode 90e. The electrolyte layer 94 is composed of a first electrolyte 94a and a second electrolyte 94b, and the outer electrode layer 92 is composed of an air electrode 92a and a current collecting layer 92b.

  In the present embodiment, the first fuel electrode 90d is formed by firing a mixture of NiO and YSZ, which is Y-doped zirconia, into a cylindrical shape. The second fuel electrode 90e is formed by depositing a mixture of NiO and GDC, which is a ceria doped with Gd, on the outside of the first fuel electrode 90d.

  In the present embodiment, the first electrolyte 94a is formed by laminating the LDC 40, which is ceria doped with lanthanum, on the outside of the second fuel electrode 90e. Furthermore, the second electrolyte 94b is formed by laminating LSGM, which is lanthanum gallate doped with Sr and Mg, on the outside of the first electrolyte 94a. A fired body was formed by firing the formed body.

  In the present embodiment, the air electrode 92a is formed by depositing LSCF, which is lanthanum cobaltite doped with Sr and Fe, on the outside of the fired body. The current collecting layer 92b is configured by forming an Ag layer outside the air electrode 92a.

Next, the fuel cell stack 14 will be described with reference to FIG. FIG. 5 is a perspective view showing a fuel cell stack of a solid oxide fuel cell (SOFC) according to an embodiment of the present invention.
As shown in FIG. 5, the fuel cell stack 14 includes 16 fuel cell units 16, and the lower end side and the upper end side of these fuel cell units 16 are a ceramic lower support plate 68 and an upper side, respectively. It is supported by the support plate 100. The lower support plate 68 and the upper support plate 100 are formed with through holes 68a and 100a through which the inner electrode terminal 86 can pass.

  Furthermore, a current collector 102 and an external terminal 104 are attached to the fuel cell unit 16. The current collector 102 includes a fuel electrode connection portion 102a that is electrically connected to an inner electrode terminal 86 attached to the inner electrode layer 90 that is a fuel electrode, and an entire outer peripheral surface of the outer electrode layer 92 that is an air electrode. And an air electrode connecting portion 102b electrically connected to each other. The air electrode connecting portion 102b is formed of a vertical portion 102c extending in the vertical direction on the surface of the outer electrode layer 92 and a plurality of horizontal portions 102d extending in a horizontal direction along the surface of the outer electrode layer 92 from the vertical portion 102c. Has been. The fuel electrode connection portion 102a is linearly directed obliquely upward or obliquely downward from the vertical portion 102c of the air electrode connection portion 102b toward the inner electrode terminal 86 positioned in the vertical direction of the fuel cell unit 16. It extends.

  Further, the inner electrode terminals 86 at the upper end and the lower end of the two fuel cell units 16 located at the ends of the fuel cell stack 14 (the far left side and the near side in FIG. 5) are external terminals, respectively. 104 is connected. These external terminals 104 are connected to the external terminals 104 (not shown) of the fuel cell unit 16 at the end of the adjacent fuel cell stack 14, and as described above, the 160 fuel cell units 16 Everything is connected in series.

Next, sensors and the like attached to the solid oxide fuel cell (SOFC) according to the present embodiment will be described with reference to FIG. FIG. 6 is a block diagram illustrating a solid oxide fuel cell (SOFC) according to an embodiment of the present invention.
As shown in FIG. 6, the solid oxide fuel cell 1 includes a control unit 110, and the control unit 110 includes operation buttons such as “ON” and “OFF” for operation by the user. An operation device 112, a display device 114 for displaying various data such as a power generation output value (wattage), and a notification device 116 for issuing a warning (warning) in an abnormal state are connected. The notification device 116 may be connected to a remote management center and notify the management center of an abnormal state.

Next, signals from various sensors described below are input to the control unit 110.
First, the combustible gas detection sensor 120 is for detecting a gas leak, and is attached to the fuel cell module 2 and the auxiliary unit 4.
The CO detection sensor 122 detects whether or not CO in the exhaust gas originally discharged to the outside through the exhaust gas passage 80 or the like leaks to an external housing (not shown) that covers the fuel cell module 2 and the auxiliary unit 4. Is to do.
The hot water storage state detection sensor 124 is for detecting the temperature and amount of hot water in a water heater (not shown).

The power state detection sensor 126 is for detecting the current and voltage of the inverter 54 and the distribution board (not shown).
The power generation air flow rate detection sensor 128 is for detecting the flow rate of power generation air supplied to the power generation chamber 10.
The reforming air flow sensor 130 is for detecting the flow rate of the reforming air supplied to the reformer 20.
The fuel flow sensor 132 is for detecting the flow rate of the fuel gas supplied to the reformer 20.

The water flow rate sensor 134 is for detecting the flow rate of pure water supplied to the reformer 20.
The water level sensor 136 is for detecting the water level of the pure water tank 26.
The pressure sensor 138 is for detecting the pressure on the upstream side outside the reformer 20.
The exhaust temperature sensor 140 is for detecting the temperature of the exhaust gas flowing into the hot water production apparatus 50.

As shown in FIG. 3, the power generation chamber temperature sensor 142 is provided on the front side and the back side in the vicinity of the fuel cell assembly 12, and detects the temperature in the vicinity of the fuel cell stack 14 to thereby detect the fuel cell stack. 14 (ie, the fuel cell 84 itself) is estimated.
The combustion chamber temperature sensor 144 is for detecting the temperature of the combustion chamber 18.
The exhaust gas chamber temperature sensor 146 is for detecting the temperature of the exhaust gas in the exhaust gas chamber 78.
The reformer temperature sensor 148 is for detecting the temperature of the reformer 20, and calculates the temperature of the reformer 20 from the inlet temperature and the outlet temperature of the reformer 20.
The outside air temperature sensor 150 is for detecting the temperature of the outside air when the solid oxide fuel cell (SOFC) is disposed outdoors. Further, a sensor for measuring the humidity or the like of the outside air may be provided.

  Signals from these sensors are sent to the control unit 110, and the control unit 110, based on data based on these signals, the water flow rate adjustment unit 28, the fuel flow rate adjustment unit 38, the reforming air flow rate adjustment unit 44, A control signal is sent to the power generation air flow rate adjusting unit 45 to control each flow rate in these units.

Next, the detailed configuration of the reformer 20 will be described with reference to FIGS.
FIG. 7 is a perspective view of the reformer 20, and FIG. 8 is a perspective view showing the inside of the reformer 20 with the top plate removed. FIG. 9 is a plan sectional view showing the flow of fuel inside the reformer 20.

  As shown in FIG. 7, the reformer 20 is a rectangular parallelepiped metal box, and is filled with a reforming catalyst for reforming fuel. Further, a pure water introduction pipe 60 for introducing water and a to-be-reformed gas introduction pipe 62 for introducing fuel and reforming air are connected to the upstream side of the reformer 20. Further, a fuel gas supply pipe 64 for discharging the internally reformed fuel is connected to the downstream side of the reformer 20. The reformer 20 is provided with eight vents 20c along the longitudinal direction. These vents 20c are provided from the bottom surface to the top surface of the reformer 20 so that the combustion gas combusted in the combustion chamber 18 (FIG. 2) below the reformer 20 can smoothly escape above the reformer 20. The vents 20 c are provided so as to penetrate therethrough, and are not communicated with the interior of the reformer 20.

  As shown in FIG. 8, inside the reformer 20, an evaporation unit 20a that is an evaporation chamber is provided on the upstream side, and a reforming unit 20b is provided on the downstream side adjacent to the evaporation unit 20a. It has been. A winding path is formed in the evaporation unit 20a by arranging a plurality of partition plates. The water introduced into the reformer 20 is evaporated in the evaporation unit 20a in a state where the temperature is increased, and becomes water vapor. Further, the fuel gas and the reforming air introduced into the reformer 20 are mixed with the water vapor while passing through the winding path of the evaporation unit 20a.

On the other hand, a meandering passage is formed in the reforming section 20b by arranging a plurality of partition plates, and the passage is filled with a catalyst. The fuel gas and the reforming air mixed in the evaporation unit 20a undergo a partial oxidation reforming reaction while passing through the passage of the reforming unit 20b. Further, when a mixture of fuel gas, water vapor, and reforming air is introduced from the evaporation unit 20a, a partial oxidation reforming reaction and a steam reforming reaction occur in the reforming unit 20b. Further, when a mixture of fuel gas and water vapor is introduced from the evaporation unit 20a, only the steam reforming reaction occurs in the reforming unit 20b.
In the present embodiment, the evaporation unit and the reforming unit are integrally configured to form one reformer. However, as a modified example, a reformer including only the reforming unit is provided. An evaporation chamber can also be provided adjacent to the upstream side.

  As shown in FIG. 9, the fuel gas, water, and reforming air introduced into the evaporation section 20a of the reformer 20 first meander and flow in the transverse direction of the reformer 20, and then the two passages. And is meandered in the longitudinal direction of the reformer 20. Further, the passages are merged again and connected to the reforming unit 20 b at the central portion of the reformer 20. The fuel or the like introduced into the reforming section 20b flows in the longitudinal direction in the center of the reforming section 20b, then splits into two, turns back, and the two passages turn back again toward the downstream end of the reforming section 20b. Then, they are merged and flow into the fuel gas supply pipe 64. The fuel is reformed by the catalyst filled in the passage while passing through the meandering passage.

  Next, referring to FIGS. 10 and 11 again, and referring again to FIGS. 2 and 3, the structure of the air heat exchanger 22 which is a heat exchanger for the power generation oxidant gas will be described in detail. FIG. 10 is a perspective view showing the metal case 8 and the air heat exchanger 22 housed in the housing 6. FIG. 11 is a cross-sectional view showing the positional relationship between the heat exchanger for heat exchanger and the evaporation section.

  As shown in FIG. 10, the air heat exchanger 22 is a heat exchanger disposed above the case 8 in the fuel cell module 2. Further, as shown in FIGS. 2 and 3, a combustion chamber 18 is formed inside the case 8, and a plurality of fuel cell units 16, a reformer 20 and the like are accommodated therein. 22 is located above these. The air heat exchanger 22 collects and uses the heat of the combustion gas that is combusted in the combustion chamber 18 and discharged as exhaust gas so as to preheat the power generation air introduced into the fuel cell module 2. It is configured. Further, as shown in FIG. 10, an evaporation chamber heat insulating material 23, which is an evaporation chamber temperature increasing heat insulating layer, is sandwiched between the upper surface of the case 8 and the bottom surface of the air heat exchanger 22. Are arranged to be. Furthermore, the outside of the air heat exchanger 22 and the case 8 shown in FIG. 10 is covered with a heat insulating material 7 as an outer heat insulating material (FIG. 2).

  As shown in FIGS. 2 and 3, the air heat exchanger 22 includes a plurality of combustion gas pipes 70 and a power generation air flow path 72. As shown in FIG. 2, an exhaust gas collecting chamber 78 is provided at one end of the plurality of combustion gas pipes 70, and the exhaust gas collecting chamber 78 is communicated with each combustion gas pipe 70. ing. Further, an exhaust gas discharge pipe 82 is connected to the exhaust gas collecting chamber 78. Further, the other end of each combustion gas pipe 70 is open, and this open end communicates with the combustion chamber 18 in the case 8 via a communication opening 8 a formed on the upper surface of the case 8. Has been.

  The combustion gas pipe 70 is a plurality of metal circular pipes oriented in the horizontal direction, and the circular pipes are arranged in parallel. On the other hand, the power generation air flow path 72 is constituted by a space outside each combustion gas pipe 70. A power generation air introduction pipe 74 is connected above one end of the power generation air flow path 72, and the air outside the fuel cell module 2 passes through the power generation air introduction pipe 74 for power generation. It is introduced into the air flow path 72. Further, a pair of communication flow paths 76 (FIGS. 3 and 10) are connected to both side surfaces of the other end of the power generation air flow path 72, and the power generation air flow path 72 and each communication flow path 76 are connected. Are communicated with each other via an exit port 76a.

  As shown in FIG. 3, a power generation air supply passage 77 is provided on each side surface of the case 8. Each communication channel 76 provided on both side surfaces of the air heat exchanger 22 communicates with an upper portion of a power generation air supply channel 77 provided on both side surfaces of the case 8. In addition, a large number of air outlets 77 a are arranged in the horizontal direction at the lower portion of each power generation air supply passage 77. The power generation air supplied through each power generation air supply path 77 is injected toward the lower side surface of the fuel cell stack 14 in the fuel cell module 2 from a large number of air outlets 77a.

A rectifying plate 21 that is a partition wall is attached to the ceiling surface inside the case 8, and the rectifying plate 21 has an opening 21 a.
The rectifying plate 21 is a plate member disposed horizontally between the ceiling surface of the case 8 and the reformer 20. The rectifying plate 21 is configured to adjust the flow of gas flowing upward from the combustion chamber 18 and guide it to the inlet (communication opening 8a) of the air heat exchanger 22. The power generation air and the combustion gas traveling upward from the combustion chamber 18 flow into the upper side of the rectifying plate 21 through the opening 21 a provided in the center of the rectifying plate 21, and the upper surface of the rectifying plate 21 and the ceiling surface of the case 8. 2 flows to the left in FIG. 2 and is led to the inlet of the heat exchanger 22 for air. Moreover, as shown in FIG. 11, the opening 21a is provided above the reforming unit 20b of the reformer 20, and the gas rising through the opening 21a is on the opposite side of the evaporation unit 20a. , Flows to the left exhaust passage 21b in FIGS. For this reason, the space above the evaporation unit 20a (the right side in FIGS. 2 and 11) acts as a gas retention space 21c in which the flow of exhaust gas is slower than the space above the reforming unit 20b.

  The heat insulating material 23 for the evaporation chamber is a heat insulating material attached to the bottom surface of the air heat exchanger 22 so as to substantially cover the whole. Therefore, the heat insulating material 23 for evaporation chamber is arrange | positioned over the whole evaporation part 20a. The evaporating chamber heat insulating material 23 is formed so that the high-temperature gas in the exhaust passage 21 b and the gas retention space 21 c formed between the upper surface of the rectifying plate 21 and the ceiling surface of the case 8 flows on the bottom surface of the air heat exchanger 22. It arrange | positions so that it may suppress direct heating. For this reason, the heat directly transmitted to the bottom surface of the air heat exchanger 22 from the exhaust gas remaining in the exhaust passage above the evaporation unit 20a is reduced, and the temperature around the evaporation unit 20a is likely to rise.

  In addition, the heat insulating material 23 for the evaporation chamber includes a heat insulating material 7 that is an outer heat insulating material covering the case 8 of the fuel cell module 2 and the entire air heat exchanger 22 in order to suppress the dissipation of heat to the outside air. Apart from this, it is a heat insulating material arranged inside the heat insulating material 7. The heat insulating material 7 is configured to have higher heat insulating properties than the heat insulating material 23 for the evaporation chamber. That is, the thermal resistance between the inner surface and the outer surface of the heat insulating material 7 is larger than the thermal resistance between the upper surface and the lower surface of the evaporation chamber heat insulating material 23. That is, when the heat insulating material 7 and the evaporation chamber heat insulating material 23 are made of the same material, the heat insulating material 7 is made thicker than the evaporation chamber heat insulating material 23.

Next, the flow of fuel, power generation air, and exhaust gas during the power generation operation of the solid oxide fuel cell 1 will be described.
First, fuel is introduced into the evaporating section 20a of the reformer 20 through the reformed gas introduction pipe 62, and pure water is introduced into the evaporating section 20a through the pure water introduction pipe 60. During the power generation operation, since the evaporation unit 20a is heated to a high temperature, the pure water introduced into the evaporation unit 20a is evaporated relatively quickly to become water vapor. The evaporated water vapor and fuel are mixed in the evaporation unit 20 a and flow into the reforming unit 20 b of the reformer 20. The fuel introduced into the reforming section 20b together with the steam is steam reformed here and reformed into a fuel gas rich in hydrogen. The fuel reformed in the reforming unit 20b goes down through the fuel gas supply pipe 64 and flows into the manifold 66 which is a dispersion chamber.

  The manifold 66 is a rectangular parallelepiped space having a relatively large volume, which is disposed on the lower side of the fuel cell stack 14, and a plurality of holes provided on the upper surface thereof constitute each fuel cell constituting the fuel cell stack 14. It communicates with the inside of the unit 16. The fuel introduced into the manifold 66 flows out from the upper end of the fuel cell unit 16 through the many holes provided on the upper surface thereof, through the fuel electrode side of the fuel cell unit 16, that is, through the inside of the fuel cell unit 16. . Further, when hydrogen gas as a fuel passes through the inside of the fuel cell unit 16, it reacts with oxygen in the air passing outside the fuel cell unit 16 as an air electrode (oxidant gas electrode) to generate a charge. Is done. The remaining fuel that is not used for power generation flows out from the upper end of each fuel cell unit 16 and is combusted in a combustion chamber 18 provided above the fuel cell stack 14.

  On the other hand, the power generation air as the oxidant gas is sent into the fuel cell module 2 through the power generation air introduction pipe 74 by the power generation air flow rate adjustment unit 45 as the power generation oxidant gas supply means. The air sent into the fuel cell module 2 is introduced into the power generation air passage 72 of the air heat exchanger 22 via the power generation air introduction pipe 74 and preheated. The preheated air flows out to each communication channel 76 via each outlet port 76a (FIG. 3). The power generation air flowing into each communication channel 76 flows downward through the power generation air supply passages 77 provided on both side surfaces of the fuel cell module 2, and the fuel cell stack 14 from a number of outlets 77a. Toward the power generation chamber 10.

  The air injected into the power generation chamber 10 comes into contact with the outer surface of each fuel cell unit 16 on the air electrode side (oxidant gas electrode side) of the fuel cell stack 14, and a part of oxygen in the air is in contact with it. Used for power generation. Moreover, the air injected to the lower part of the power generation chamber 10 through the blower outlet 77a rises in the power generation chamber 10 while being used for power generation. The air rising in the power generation chamber 10 burns the fuel flowing out from the upper end of each fuel cell unit 16. The combustion heat generated by this combustion heats the evaporation section 20a and the reforming section 20b of the reformer 20 disposed above the fuel cell stack 14. The combustion gas generated by burning the fuel heats the upper reformer 20 and then flows into the upper side of the rectifying plate 21 through the opening 21 a above the reformer 20. The combustion gas that has flowed into the upper side of the rectifying plate 21 is guided to the communication opening 8 a that is the inlet of the air heat exchanger 22 through the exhaust passage 21 b formed by the rectifying plate 21. The combustion gas that has flowed into the air heat exchanger 22 from the communication opening 8 a flows into the open end of each combustion gas pipe 70 and flows through the power generation air flow path 72 outside each combustion gas pipe 70. Are exchanged with each other and collected in an exhaust gas collecting chamber 78. The exhaust gas collected in the exhaust gas collection chamber 78 is discharged to the outside of the fuel cell module 2 through the exhaust gas discharge pipe 82. As a result, the evaporation of water in the evaporation unit 20a and the steam reforming reaction, which is an endothermic reaction in the reforming unit 20b, are promoted, and the power generation air in the air heat exchanger 22 is preheated.

Next, control in the starting process of the solid oxide fuel cell 1 will be described with reference to FIGS.
FIG. 12 is a control flowchart in the startup process. FIG. 13 is a table showing the supply amounts of fuel, reforming air, water, and power generation air at each stage of the startup process. FIG. 14 is a time chart illustrating an example of each supply amount of fuel and the temperature of each part in the startup process. Note that the scale on the vertical axis in FIG. 14 indicates the temperature, and each supply amount of fuel or the like schematically indicates the increase or decrease in the amount.

In the starting process shown in FIGS. 12 to 14, the temperature of the fuel cell stack 14 in a normal temperature state is raised to a temperature at which power generation is possible.
First, in step S1 of FIG. 12, the control part 110 operates the water flow rate adjustment unit 28 which is a water supply means for a predetermined time. In the initial stage of startup, the pure water introduction pipe 60 extending from the water flow rate adjustment unit 28 to the evaporation section 20a of the reformer 20 is filled with air. Further, since the flow rate of water supplied by the water flow rate adjustment unit 28 is extremely small, there is a time lag after the water flow rate adjustment unit 28 is operated until the water actually flows into the evaporation unit 20a. Therefore, in the initial stage of start-up, by operating the water flow rate adjusting unit 28 for a predetermined time, the air in the pure water introduction pipe 60 is purged and the pure water introduction pipe 60 is filled with reforming water. Keep it. In the present embodiment, the controller 110 operates the water flow rate adjustment unit 28 for about 2 minutes at a water supply rate of about 3 cc / min, stops it, and stops the water flow rate adjustment unit during the subsequent ignition process. 28 is stopped.

  Next, in step S2 in FIG. 12, supply of power generation air and reforming air is started (time t0 in FIG. 14). Specifically, the control unit 110 that is a control unit sends a signal to the power generation air flow rate adjustment unit 45 that is a power generation oxidant gas supply unit and operates it. As described above, the power generation air is introduced into the fuel cell module 2 through the power generation air introduction pipe 74 and flows into the power generation chamber 10 through the air heat exchanger 22 and the power generation air supply path 77. . In addition, the control unit 110 sends a signal to the reforming air flow rate adjusting unit 44 which is a reforming oxidant gas supply means to operate it. The reforming air introduced into the fuel cell module 2 flows into the interior of each fuel cell unit 16 through the reformer 20 and the manifold 66, and flows out from the upper end thereof. Note that at time t0, no reforming reaction occurs in the reformer 20 because fuel has not yet been supplied. In this embodiment, the supply amount of power generation air started at time t0 in FIG. 14 is about 100 L / min, and the supply amount of reforming air is about 10.0 L / min (see “ (See “Purge”).

  Next, fuel supply is started at time t1 after a predetermined time from time t0 in FIG. 14 (step S3 in FIG. 12). Specifically, the control unit 110 sends a signal to the fuel flow rate adjustment unit 38 which is a fuel supply means to operate it. In the present embodiment, the fuel supply amount started at time t1 is about 5.0 L / min (see “ignition” in FIG. 13). Further, the reforming air supply amount is reduced to about 9.0 L / min, and the power generation air supply amount is maintained at the previous value. The fuel introduced into the fuel cell module 2 flows into the interior of each fuel cell unit 16 through the reformer 20 and the manifold 66, and flows out from the upper end thereof. At time t1, the reformer reaction is not generated in the reformer 20 because the temperature of the reformer is still low.

  Next, in step S4 of FIG. 12, it is determined whether or not it is time to ignite. Specifically, it is determined whether a predetermined time has elapsed from time t1 in FIG. 14 and preparation for ignition is completed. If the predetermined time has not elapsed since time t1, the process of step S4 is repeated. At time t2 when a predetermined time has elapsed from time t1, step S5 in FIG. 12 is executed, and an ignition process for the supplied fuel is started. Specifically, in the ignition process, the control unit 110 sends a signal to an ignition device 83 (FIG. 2) that is an ignition means, and ignites the fuel flowing out from the upper end of each fuel cell unit 16. The ignition device 83 repeatedly generates a spark in the vicinity of the upper end of the fuel cell stack 14 and ignites the fuel flowing out from the upper end of each fuel cell unit 16.

  Next, in step S6 of FIG. 12, whether or not ignition is completed by the ignition determination means 110a (FIG. 6) built in the control unit 110, that is, fuel flowing out from the upper end of each fuel cell unit 16. It is determined whether or not the fuel is continuously burned. If the ignition is completed, the process proceeds to step S7. If the ignition is not completed, the process of step S6 is repeated. Specifically, in the ignition determination unit 110a, the temperature detected by the power generation chamber temperature sensor 142, which is a temperature detection unit disposed in the vicinity of the upper end of the fuel cell stack 14, has increased by 10 ° C. or more than before the start of ignition. In this case, it is determined that the ignition has been completed (see “ignition” in FIG. 13). Alternatively, the detection temperature of the exhaust temperature sensor 140 (FIG. 6) for detecting the temperature of the exhaust from the fuel cell module 2, the detection temperature of the reformer temperature sensor 148 (FIG. 6) for detecting the temperature of the reformer 20, or The present invention can also be configured to determine whether ignition has been completed based on a combination of a plurality of detected temperatures.

When it is determined that the ignition has been completed at time t3 in FIG. 14, the process proceeds to step S7, and after step S7, an activation process after completion of ignition (after time t3 in FIG. 14) is executed.
When ignition completion is determined at time t3 in FIG. 14, supply of reforming water is started. Specifically, the control unit 110 sends a signal to the water flow rate adjustment unit 28 (FIG. 6), which is a water supply means, and operates it. As described above, the water flow rate adjusting unit 28 is operated for a predetermined time before the time t0 in FIG. 14 to purge the air in the pure water introduction pipe 60, and in the pure water introduction pipe 60, there is water for reforming. Is full. For this reason, water flows into the evaporator 20a of the reformer 20 immediately after the operation of the water flow rate adjustment unit 28 is started. Thereby, the steam for steam reforming can be generated at an appropriate time without causing a time lag.

In the present embodiment, the supply amount of water started at time t3 is 2.0 cc / min. At time t3, the fuel supply amount is maintained at about 5.0 L / min (see “ATR1” in FIG. 13). Further, the supply amounts of the power generation air and the reforming air are also maintained at the previous values. At time t3, the ratio O ₂ / C of oxygen O ₂ in the reforming air and carbon C in the fuel becomes about 0.32 (see the column “O ₂ / C” in FIG. 13). Here, the ratio O ₂ / C = 1 corresponds to a state in which the number of carbon atoms C in the fuel is equal to the number of oxygen molecules O ₂ in the reforming air. Therefore, theoretically, in the state of the ratio O ₂ /C=0.5, all the carbon atoms C in the fuel react with all the oxygen molecules O ₂ in the reforming air. When all of the carbon becomes carbon monoxide and the ratio O ₂ / C is less than 0.5, excess carbon is generated, and troubles such as carbon deposition occur. However, in practice, since a minute amount of moisture contained in the reforming air reacts with carbon in the fuel, the value of the ratio O ₂ / C can be reduced to about 0.4 without causing carbon deposition. There is a case. Therefore, the ratio O ₂ /C=0.32 in the ATR1 process is a state in which reforming air is insufficient to partially oxidize and reform the entire amount of supplied fuel.

  At time t3, the ratio S / C between the water vapor S generated by the supplied water and the carbon C in the fuel is 0.43 (see the “S / C” column in FIG. 13). Here, the ratio S / C = 1 means a state in which the total amount of carbon contained in the supplied fuel is chemically steam-reformed by the supplied water (steam). Accordingly, the ratio S / C = 0.43 is a state in which the reforming water is insufficient to steam reform the entire amount of the supplied fuel. Further, in practice, surplus carbon is generated in the reformer 20 with the amount of steam at which S / C = 1, so that when all the supplied fuel is steam reformed, S / C = An appropriate amount of water vapor is about 2.5.

  After being ignited at time t3 in FIG. 14, the supplied fuel flows out from the upper end of each fuel cell unit 16 as off-gas and is burned here. This combustion heat heats the evaporation section 20a and the reforming section 20b of the reformer 20 disposed above the fuel cell stack 14. Here, an evaporating chamber heat insulating material 23 is disposed above the reformer 20 (above the case 8), so that the temperature of the evaporating section 20a and the reforming section 20b immediately after the start of fuel combustion. Rises rapidly from room temperature. Since the outside air is introduced into the air heat exchanger 22 disposed on the heat insulating material 23 for the evaporation chamber, the air heat exchanger 22 has a low temperature, particularly immediately after the start of combustion, and serves as a cooling source. Cheap. In the present embodiment, the evaporation chamber heat insulating material 23 is disposed between the upper surface of the case 8 and the bottom surface of the air heat exchanger 22, so that the reformer 20 disposed in the upper portion of the case 8 The movement of heat to the air heat exchanger 22 is suppressed, and heat is easily trapped in the vicinity of the reformer 20 in the case 8. In addition, the space above the rectifying plate 21 above the evaporation unit 20a is configured as a gas retention space 21c (FIG. 2) in which the flow of combustion gas is slow, so that the vicinity of the evaporation unit 20a is double insulated. And the temperature rises more rapidly.

  As described above, the temperature of the evaporation unit 20a rapidly increases, so that water vapor can be generated in a short time after the start of off-gas combustion. In addition, since the reforming water is supplied to the evaporation unit 20a little by little, it is possible to heat the water to the boiling point with a slight amount of heat compared to the case where a large amount of water is stored in the evaporation unit 20a. The supply of water vapor can be started immediately. Furthermore, as described above, since water flows in immediately after the operation of the water flow rate adjustment unit 28 without causing a time lag in the evaporation unit 20a, an excessive temperature rise of the evaporation unit 20a due to a delay in water supply, and A delay in the supply of water vapor can be avoided.

  When a certain amount of time elapses after the start of off-gas combustion, the temperature of the air heat exchanger 22 also rises due to the exhaust gas flowing from the combustion chamber 18 into the air heat exchanger 22. The evaporation chamber heat insulating material 23 that insulates between the reformer 20 and the air heat exchanger 22 is a heat insulating material provided inside the heat insulating material 7. Therefore, the heat insulating material 23 for the evaporation chamber does not suppress the dissipation of heat from the fuel cell module 2, but immediately increases the temperature of the reformer 20, particularly the evaporation section 20a immediately after the start of off-gas combustion. It is arranged for the purpose. For this reason, the heat insulating material 23 for the evaporation chamber is designed to have a sufficient thermal resistance necessary to achieve this purpose, and is configured to have a thermal resistance smaller than that of the heat insulating material 7.

In this way, at time t4 when the temperature of the reformer 20 rises, the fuel and the reforming air that have flowed into the reforming unit 20b through the evaporation unit 20a undergo the partial oxidation reforming reaction represented by the equation (1). Get up.
_{C m H n + xO 2 →} aCO 2 + bCO + cH 2 (1)
Since this partial oxidation reforming reaction is an exothermic reaction, when the partial oxidation reforming reaction occurs in the reforming part 20b, the ambient temperature rapidly rises locally.

On the other hand, in the present embodiment, the supply of the reforming water is started from time t3 immediately after the ignition is confirmed, and the temperature of the evaporation unit 20a is rapidly increased. At time t4, water vapor has already been generated in the evaporator 20a and supplied to the reformer 20b. That is, after the off-gas is ignited, the supply of water is started a predetermined time before the temperature of the reforming unit 20b reaches the temperature at which the partial oxidation reforming reaction occurs, and reaches the temperature at which the partial oxidation reforming reaction occurs. At that time, a predetermined amount of water is stored in the evaporation unit 20a, and water vapor is generated. For this reason, when the temperature rapidly rises due to the occurrence of the partial oxidation reforming reaction, a steam reforming reaction occurs in which the reforming steam supplied to the reforming unit 20b reacts with the fuel. This steam reforming reaction is an endothermic reaction shown in Formula (2), and occurs at a higher temperature than the partial oxidation reforming reaction.
C _m H _n + xH ₂ O → aCO ₂ + bCO + cH ₂ (2)

As described above, when the time t4 in FIG. 14 is reached, the partial oxidation reforming reaction occurs in the reforming unit 20b, and the steam reforming is caused by the temperature rise caused by the partial oxidation reforming reaction. Reaction will also occur at the same time. Therefore, the reforming reaction that occurs in the reforming unit 20b after time t4 is an autothermal reforming reaction (ATR) shown in Formula (3) in which the partial oxidation reforming reaction and the steam reforming reaction are mixed. That is, the ATR1 process is started at time t4.
_{C m H n + xO 2 +} yH 2 O → aCO 2 + bCO + cH 2 (3)

  Thus, in the solid oxide fuel cell 1 according to the embodiment of the present invention, water is supplied during the entire start-up process, and the partial oxidation reforming reaction (POX) does not occur alone. In the time chart shown in FIG. 14, the reformer temperature at time t4 is about 200.degree. The reformer temperature is lower than the temperature at which the partial oxidation reforming reaction occurs, but the temperature detected by the reformer temperature sensor 148 (FIG. 6) is the average temperature of the reforming unit 20b. Actually, even at time t4, the reforming unit 20b partially reaches the temperature at which the partial oxidation reforming reaction occurs, and the steam reforming reaction is performed by the reaction heat of the generated partial oxidation reforming reaction. Is also triggered. As described above, in this embodiment, after the ignition, the supply of water is started before the reforming unit 20b reaches the temperature at which the partial oxidation reforming occurs, and the partial oxidation reforming reaction is performed independently. Will not occur.

Further, as described above, the partial oxidation reforming reaction is an exothermic reaction, and the steam reforming reaction is an endothermic reaction. For this reason, if an excessive steam reforming reaction is generated in the reforming unit 20b at the initial stage of the start-up process where the temperature in the fuel cell module 2 is still low, the temperature of the reforming unit 20b is lowered. In the present embodiment, by setting the values of O ₂ / C and S / C in the ATR1 step to appropriate values, the temperature of the reforming unit 20b is successfully increased while inducing the steam reforming reaction. doing.

Further, the carbon monoxide generated by the autothermal reforming reaction in the reforming unit 20b and the water vapor remaining without being used for reforming pass through the fuel gas supply pipe 64 and the manifold 66 (FIG. 2) to each fuel. It reaches the fuel electrode of the battery cell unit 16. As described above, since nickel is used for the first fuel electrode 90d and the second fuel electrode 90e (FIG. 4B) of each fuel cell unit 16, carbon monoxide and water vapor are caused by the catalytic action of nickel. However, the shift reaction shown in Formula (4) occurs. That is, a shift reaction is induced at the fuel electrode of each fuel cell unit 16 in a state where the temperature of the reforming unit 20b has reached the temperature at which the partial oxidation reforming reaction occurs.
CO + H ₂ O → CO ₂ + H ₂ (4)

  This shift reaction produces carbon dioxide and hydrogen from carbon monoxide and water vapor. Here, since the shift reaction is an exothermic reaction, the shift reaction occurs at the fuel electrode of each fuel cell unit 16, thereby heating the fuel cell unit 16. Further, hydrogen generated by the shift reaction flows out from the upper end of each fuel cell unit 16 and is combusted in the combustion chamber 18. For this reason, the reformer 20 is heated more strongly by the occurrence of the shift reaction.

  Here, it is known that the shift reaction occurs in a temperature range where the activation temperature range is about 500 ° C. to 600 ° C., the lower limit temperature is about 500 ° C., and the upper limit temperature is about 650 ° C. Yes. In the initial stage of the start-up process (from time t4), the temperature of each fuel cell unit 16 does not reach the temperature at which the shift reaction occurs as a whole, but the temperature of the high temperature that has flowed out of the reformer 20 When carbon oxide and water vapor come into contact with the surface of the fuel electrode of each fuel cell unit 16, the temperature rises locally. As a result, it has been confirmed that a shift reaction occurs even in the initial stage of the startup process. Further, in the present embodiment, each fuel cell is designed by appropriately designing the configuration, arrangement, and size of the fuel gas supply pipe 64 and the manifold 66 that lead the fuel from the reformer 20 to each fuel cell unit 16. The temperature of the carbon monoxide and water vapor reaching the unit 16 is adjusted to effectively induce the shift reaction. Furthermore, in the present embodiment, nickel that acts as a catalyst for the shift reaction is used for the fuel electrode of the fuel cell unit 16 and the length of the fuel cell unit 16 is appropriately designed, so that The shift reaction is actively induced. In addition to nickel, various precious metals are known to act as catalysts for shift reactions.

  As described above, in the solid oxide fuel cell 1 according to the embodiment of the present invention, the evaporator 20a of the reformer 20 is disposed above the fuel cell stack 14, so that it is directly generated by the combustion heat of the offgas. The evaporator 20a is heated. Further, in the solid oxide fuel cell 1 of the present embodiment, the evaporation chamber heat insulating material 23 is disposed above the evaporation unit 20a, and a gas retention space 21c is formed, so that the evaporation unit 20a is rapidly formed at the initial stage of the starting process. The temperature is increased, and steam is supplied at the start of the reforming reaction. In addition, in the solid oxide fuel cell 1 of the present embodiment, the fuel cell unit 16, the fuel gas supply pipe 64, and the manifold 66 are appropriately designed so that the fuel electrode of the fuel cell unit 16 can be actively used. It induces shift reaction. With these configurations, the partial oxidation reforming reaction in the reformer 20 is prevented from occurring independently in the start-up process, and the autothermal reforming reaction is generated from the beginning of the reforming reaction. Thereby, when the reforming part 20b runs out of heat, the temperature rises excessively and the reformer 20 and the reforming catalyst are prevented from being deteriorated. Further, in the solid oxide fuel cell 1 of the present embodiment, the POX that generates the partial oxidation reforming reaction independently by using the reaction heat of the shift reaction and the combustion heat of hydrogen generated by the shift reaction. While omitting the steps, the temperature of the reformer 20 and the fuel cell stack 14 has been successfully increased quickly and stably by the ATR1 step.

  Next, in step S8 of FIG. 12, it is determined whether or not the temperature of the reformer 20 has reached a predetermined ATR2 process transition temperature. If the ATR2 process transition temperature has been reached, the process proceeds to step S9. If not, the process of step S8 is repeated. In the present embodiment, when the temperature detected by the reformer temperature sensor 148 reaches about 500 ° C. or more, the process shifts from the ATR1 process to the ATR2 process.

Next, in step S9, the water supply amount is changed from 2.0 cc / min to 3.0 cc / min (see “ATR2 process” in FIG. 13 and time t5 in FIG. 14). Further, the fuel supply amount, the reforming air supply amount, and the power generation air supply amount are maintained at the previous values. As a result, the steam / carbon ratio S / C in the ATR2 step is increased to 0.64, while the reforming air / carbon ratio O ₂ / C is maintained at 0.32. Thus, by maintaining the ratio of reforming air and carbon O ₂ / C constant, the ratio S / C of steam and carbon is increased, so that the amount of carbon that can be partially oxidized and reformed is not reduced. In addition, the amount of carbon that can be steam reformed is increased. This makes it possible to increase the amount of carbon subjected to steam reforming as the temperature of the reforming unit 20b increases while reliably avoiding the risk of carbon deposition in the reforming unit 20b.

  Further, in step S10 of FIG. 12, it is determined whether or not the temperature of the fuel cell stack 14 has reached a predetermined ATR3 process transition temperature. If the ATR3 process transition temperature has been reached, the process proceeds to step S11. If not, the process of step S10 is repeated. In the present embodiment, when the temperature detected by the power generation chamber temperature sensor 142 reaches about 400 ° C. or more, the process shifts from the ATR2 process to the ATR3 process.

Next, in step S11, the fuel supply amount is changed from 5.0 L / min to 4.0 L / min, and the reforming air supply amount is changed from 9.0 L / min to 6.5 L / min (FIG. 13 “ATR3 step” and time t6 in FIG. 14). Also, the previous values are maintained for the water supply amount and the power generation air supply amount. This increases the steam / carbon ratio S / C in the ATR3 step to 0.80, while the reforming air to carbon ratio O ₂ / C is reduced to 0.29. In this way, carbon that can be partially oxidized and reformed while avoiding the risk of temperature drop due to a rapid increase in steam reforming by reducing the reforming air supply while maintaining the water supply constant. The amount of steam can be reduced and the rate of steam reforming reaction can be increased. As described above, the ATR process is executed in three stages of ATR1, ATR2, and ATR3. The water flow rate adjustment unit 28 is configured so that the water supply amount in the ATR1 process, which is the initial stage of the ATR process, is minimized. Is controlled. Also, by executing the ATR process in multiple stages, the supply ratio of fuel, reforming air, and reforming water is changed at each stage, avoiding temperature drop due to excessive steam reforming However, the temperatures of the reformer 20 and the fuel cell stack 14 are raised by the autothermal reforming reaction.

  Further, in step S12 of FIG. 12, it is determined whether or not the temperature of the fuel cell stack 14 has reached a predetermined SR1 process transition temperature. If the SR1 process transition temperature has been reached, the process proceeds to step S13, and if not, the process of step S12 is repeated. In the present embodiment, when the temperature detected by the power generation chamber temperature sensor 142 reaches about 550 ° C. or higher, the process proceeds to the SR1 process.

  Next, in step S13, the fuel supply amount is changed from 4.0 L / min to 3.0 L / min, and the water supply amount is changed from 3.0 cc / min to 7.0 cc / min (see “ SR1 process "and time t7 in FIG. 14). Further, the supply of the reforming air is stopped, and the power supply air supply amount is maintained at the previous value. Thus, in the SR1 process, steam reforming occurs exclusively in the reforming unit 20b, and the steam / carbon ratio S / C is 2 which is appropriate for steam reforming the entire amount of supplied fuel. .49. At time t7 in FIG. 14, since the temperature of both the reformer 20 and the fuel cell stack 14 is sufficiently increased, the steam reforming is performed even if the partial oxidation reforming reaction has not occurred in the reforming unit 20b. The reaction can be generated stably.

  Furthermore, in step S14 of FIG. 12, it is determined whether or not the temperature of the fuel cell stack 14 has reached a predetermined SR2 process transition temperature. If the SR2 process transition temperature has been reached, the process proceeds to step S15. If not, the process of step S14 is repeated. In the present embodiment, when the temperature detected by the power generation chamber temperature sensor 142 reaches about 600 ° C. or higher, the process proceeds to the SR2 process.

  Next, in step S15, the fuel supply amount is changed from 3.0 L / min to 2.5 L / min, and the water supply amount is changed from 7.0 cc / min to 6.0 cc / min (see “ SR2 process "and time t8 in FIG. 14). In addition, the previous value of the power supply air supply amount is maintained. Thereby, in the SR2 step, the ratio S / C of water vapor to carbon is set to 2.56. Thus, in the present embodiment, only the ATR process (ATR1 process, ATR2 process, and ATR3 process) and the SR process (SR1 process and SR2 process) are executed as the fuel reforming process executed in the startup process. Is done.

  Furthermore, after executing the SR2 process for a predetermined time, the process proceeds to the power generation process, and the process of the flowchart shown in FIG. In the power generation process, power is extracted from the fuel cell stack 14 to the inverter 54 (FIG. 6), and power generation is started. In the power generation process, the reforming unit 20b reforms the fuel exclusively by steam reforming.

  According to the solid oxide fuel cell 1 of the embodiment of the present invention, in an off-gas combustion cell burner type solid oxide fuel cell, it is possible to generate steam for steam reforming at the initial stage of the start-up process. Therefore, the evaporator 20a is disposed above the plurality of fuel cell units 16 and is disposed adjacent to the reformer 20b (FIGS. 2 and 3). By adopting such a configuration, the reforming air flow rate adjustment unit 44 and the partial oxidation reforming reaction are prevented from occurring independently in the reforming unit 20b while enabling the generation of water vapor at an early stage, and By controlling the water flow rate adjusting unit 28, the thermal runaway of the reforming unit 20b is prevented.

  Further, according to the solid oxide fuel cell 1 of the present embodiment, the ATR process (time t4 to t7 in FIG. 14) in which the partial oxidation reforming reaction and the steam reforming reaction occur simultaneously in the reforming unit 20b, Since only the SR step (time t7 in FIG. 14) in which only the steam reforming reaction occurs is executed, the partial oxidation reforming reaction which is an exothermic reaction does not occur alone in the reforming unit 20b. The deterioration and damage of the reforming part 20b due to the thermal runaway of the reforming reaction can be prevented.

Further, the solid oxide fuel cell 1 of the present embodiment, than the ratio O ₂ /C=0.4 carbon C of oxygen O ₂ and fuel in the air for reforming, always oxygen O ₂ Therefore, the reforming air flow rate adjustment unit 44 is controlled so that the ratio of oxygen is reduced (see the column “O ₂ / C” in FIG. 13). O ₂ is insufficient and a steam reforming reaction is always induced, so that the reforming part can be reliably protected.

  Further, according to the solid oxide fuel cell 1 of the present embodiment, the ATR process is executed separately for ATR1, ATR2, and ATR3 (time t4 to t7 in FIG. 14), and water is supplied in the initial stage of the ATR process. Since the amount is minimized (see the “pure water flow rate” column in FIG. 13), the endothermic reaction due to the steam reforming reaction occurring at the beginning of the start-up process where the temperature of the reforming section is low is suppressed, and the temperature of the reforming section is reduced. It can surely be raised.

  Furthermore, according to the solid oxide fuel cell 1 of the present embodiment, the water flow adjustment unit 28 starts supplying water before the temperature of the reforming unit 20b reaches the temperature at which the partial oxidation reforming reaction occurs. 14 (time t3 in FIG. 14), the water supplied in advance is converted into water vapor in the evaporator 20a and reaches a temperature at which the partial oxidation reforming reaction occurs (time t4 in FIG. 14). Water vapor can be supplied to the portion 20b.

  Further, according to the solid oxide fuel cell 1 of the present embodiment, after the ignition, the supply of water is started (steps S6 → S7 in FIG. 12). Generation | occurrence | production of reaction is avoided and single generation | occurrence | production of a partial oxidation reforming reaction and the temperature fall of the modification part 20b are prevented reliably.

  Furthermore, according to the solid oxide fuel cell 1 of the present embodiment, the water flow rate adjustment unit 28 is operated (step S1 in FIG. 12) before performing the ignition process (steps S5 and S6 in FIG. 12). It is possible to purge the air in the pipe leading water to the evaporation unit 20a in advance, and to shorten the time lag of water supply when the water flow rate adjustment unit 28 is operated after ignition (step S7 in FIG. 12). The water can be supplied into the evaporator 20b at an appropriate time.

  Further, according to the solid oxide fuel cell 1 of the present embodiment, the amount of air supplied for reforming is kept constant when the process shifts from the ATR1 process to the ATR2 process (time t5 in FIG. 14). The ratio of steam reforming is increased while maintaining the amount of carbon that can be reformed by oxidation reforming, and the risk of carbon deposition in the reforming section 20b and temperature drop in the reforming section 20b can be suppressed.

  Furthermore, according to the solid oxide fuel cell 1 of the present embodiment, the fuel supply amount is kept constant when the process shifts from the ATR1 process to the ATR2 process (time t5 in FIG. 14). It is possible to prevent the reforming reaction from becoming unstable in a state where the temperature is low, and it is possible to raise the temperature of the reforming unit 20b stably.

  Further, according to the solid oxide fuel cell 1 of the present embodiment, the fuel supply amount and the reforming fuel are used at the time of transition from the ATR2 process (time t6 in FIG. 14) when the temperature of the reforming unit 20b is relatively increased. Since the air supply amount is changed, the risk of destabilization of the reforming reaction can be minimized.

As mentioned above, although preferable embodiment of this invention was described, a various change can be added to embodiment mentioned above.
In the above-described embodiment, the heat insulating layer 23 for the evaporation chamber disposed between the upper surface of the case 8 and the air heat exchanger 22 is provided as the heat insulating layer for evaporating chamber temperature rising. The heat insulation layer for evaporating chamber temperature rising can also be comprised as shown in FIG.

  In the modification shown in FIG. 15, the heat-insulating layer for evaporating the evaporation chamber is composed of an air layer 223 formed between the evaporation unit 20 a and the air heat exchanger 22. The air layer 223 is configured by a sealed space between the evaporation unit 20 a and the air heat exchanger 22. The air layer 223 configured as described above suppresses the movement of heat from the evaporation unit 20a to the heat exchanger 22 for air, so that the temperature of the evaporation unit 20 can be rapidly increased in the initial stage of the startup process. In the modification shown in FIG. 15, the air layer 223 is configured by a sealed space, but the air layer 223 can be configured by an open space that is not communicated with the combustion chamber 18, or The exhaust gas in the combustion chamber 18 is formed so as to be difficult to flow in, and can also be configured by a gas retention space in which gas is retained.

DESCRIPTION OF SYMBOLS 1 Solid oxide fuel cell 2 Fuel cell module 4 Auxiliary machine unit 7 Heat insulating material (outer heat insulating material)
8 Case 10 Power generation chamber 12 Fuel cell assembly 14 Fuel cell stack 16 Fuel cell unit (solid oxide fuel cell)
18 Combustion chamber 20 Reformer 20a Evaporating section (evaporating chamber)
20b reforming part 21 current plate (partition wall)
21a Opening 21b Exhaust passage 21c Gas retention space 22 Air heat exchanger (heat exchanger for power generation oxidant gas)
23 Heat insulation material for evaporation chamber (heat insulation layer for evaporation chamber temperature rise)
24 Water supply source 26 Pure water tank 28 Water flow rate adjustment unit (water supply means)
30 Fuel supply source 38 Fuel flow rate adjustment unit (fuel supply means)
40 Air supply source 44 Reforming air flow rate adjusting unit (reforming oxidant gas supply means)
45 Air flow adjustment unit for power generation (oxidant gas supply means for power generation)
46 1st heater 48 2nd heater 50 Hot water production apparatus (heat exchanger for exhaust heat recovery)
52 Control box 54 Inverter 60 Pure water introduction pipe 62 Reformed gas introduction pipe 66 Manifold (dispersion chamber)
70 Combustion gas piping 72 Power generation air flow path 74 Power generation air introduction pipe 76 Communication flow path 76 Outlet port 77 Power generation air supply path 77a Air outlet 82 Exhaust gas discharge pipe 83 Ignition device (ignition means)
84 Fuel cell 86 Inner electrode terminal 88 Fuel gas flow path (internal passage)
90 inner electrode layer 92 outer electrode layer 94 electrolyte layer 110 control unit (control means)
110a Ignition determination means 112 Operation device 114 Display device 116 Alarm device 126 Power state detection sensor (demand power detection means)
132 Fuel flow sensor (fuel supply detection sensor)
138 Pressure sensor (reformer pressure sensor)
142 Power generation chamber temperature sensor (temperature detection means)
148 Reformer Temperature Sensor 150 Outside Air Temperature Sensor 223 Air Layer (Evaporation Chamber Heat-Insulating Layer)

Claims (10)

A solid oxide fuel cell of an off-gas combustion cell burner system in which the fuel supplied to the fuel cell is flowed out from one end and the reformed portion is heated by burning out the off-gas,
A fuel cell module comprising a plurality of fuel cell units each having a fuel electrode formed in an internal passage through which fuel passes;
A partial oxidation reforming reaction that is arranged above the plurality of fuel battery cell units in the fuel cell module and chemically reacts with the fuel and an oxidizing gas for reforming, and the fuel and reforming A reforming section that generates hydrogen by a steam reforming reaction by chemically reacting the steam of
Above the plurality of fuel cell units, adjacent to the reforming unit, an evaporation chamber for evaporating the supplied water,
A combustion chamber disposed in the fuel cell module and burning the fuel that has passed through the internal passage at the upper end of each fuel cell unit, and heating the reforming unit and the evaporation chamber above;
Fuel supply means for supplying the fuel reformed in the reforming section to the fuel cell units by supplying fuel to the reforming section;
A reforming oxidant gas supply means for supplying a reforming oxidant gas to the reforming section;
Water supply means for supplying reforming water to the evaporation chamber;
Power generation oxidant gas supply means for supplying power generation oxidant gas to the oxidant gas electrodes of the plurality of fuel cell units;
In the starting step of the fuel cell module, the fuel supply means, the reforming oxidant gas supply means, and the water supply means are controlled to perform a partial oxidation reforming reaction and a steam reforming reaction in the reforming section. And a control means for raising the temperature of the plurality of fuel battery cell units to a temperature at which power generation is possible,
The control means controls the oxidant gas supply means for reforming and the water supply means so that a partial oxidation reforming reaction does not occur independently in the reforming section during the entire startup process. A solid oxide fuel cell.   The control means includes an ATR process in which a partial oxidation reforming reaction and a steam reforming reaction occur simultaneously in the reforming section, and a steam reforming reaction only in the reforming section as a fuel reforming process in the reforming section. 2. The solid oxide fuel cell according to claim 1, wherein only the SR process in which the generation occurs is executed. The control means is configured such that the supply amount of the reforming oxidant gas is oxygen O ₂ in the reforming oxidant gas, which is capable of reforming the fuel only by the partial oxidation reforming reaction in the reforming section. 3. The solid oxide type according to claim 2, wherein the reforming oxidant gas supply means is controlled so that the ratio of oxygen O ₂ is always smaller than the ratio of carbon C in the fuel, O ₂ /C=0.4. Fuel cell.   4. The solid oxide according to claim 3, wherein the control means executes the ATR process in a plurality of stages, and controls the water supply means so that a water supply amount is minimized in an initial stage of the ATR process. Type fuel cell.   The control means may prevent water from the water supply means before the temperature of the reforming section reaches a temperature at which the partial oxidation reforming reaction occurs so that the partial oxidation reforming reaction does not occur alone in the reforming section. The solid oxide fuel cell according to claim 4, wherein the supply of is started.   The control means uses the water supply means after the fuel that has passed through the internal passages of the fuel cell units is ignited and before the temperature of the reforming section reaches the temperature at which the partial oxidation reforming reaction occurs. The solid oxide fuel cell according to claim 5, wherein the supply of water is started.   The control means operates the water supply means before executing the ignition process for igniting the fuel that has passed through the internal passages of the fuel cell units, and stops the water supply means during the ignition process, 7. The solid oxide fuel cell according to claim 6, wherein water supply by the water supply means is started after ignition.   When the control means shifts from the ATR1 process, which is the initial stage of the ATR process, to the ATR2 process, which is the next stage, the water supply amount is increased while the oxidant gas supply amount for reforming is kept constant. The solid oxide fuel cell according to claim 4, which is maintained.   9. The solid oxide fuel cell according to claim 8, wherein the control means maintains a constant fuel supply amount when shifting from the ATR1 step to the ATR2 step.   The control means is configured to execute the ATR3 step after the ATR2 step, and changes the fuel supply amount and the oxidizing gas supply amount for reforming when the ATR2 step is shifted to the ATR3 step. On the other hand, the solid oxide fuel cell according to claim 9, wherein the water supply amount is kept constant.

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