JP2010238617A - Solid electrolyte fuel battery - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a solid electrolyte fuel battery capable of precisely judging deterioration of a fuel battery module. <P>SOLUTION: The solid electrolyte fuel battery 1 to vary an output electric power according to a demand power generation amount has the fuel battery module 2 equipped with a plurality of solid electrolyte fuel battery cells 16, a fuel supply means 38 of supplying fuel to this fuel battery module, an oxidant gas supply means 45 of supplying the oxidant gas to the fuel battery module, a water supply means 28 of supplying water to the fuel cell module, and a control means of changing an amount of the fuel supplied from the fuel supply means corresponding to the demand power generation amount. The control means is equipped with a deterioration judging means of judging deterioration of the fuel battery module, and this deterioration judging means carries out deterioration judgment when the fuel battery module is operated in a stable operational state. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a solid oxide fuel cell, and more particularly to a solid oxide fuel cell in which output power is variable according to a required power generation amount.

  A solid oxide fuel cell (hereinafter also referred to as “SOFC”) uses an oxide ion conductive solid electrolyte as an electrolyte, has electrodes attached to both sides thereof, supplies fuel gas on one side, and supplies the other This is a fuel cell that operates at a relatively high temperature by supplying an oxidizing agent (air, oxygen, etc.) to the side.

  In this SOFC, water vapor or carbon dioxide is generated by the reaction between oxygen ions that have passed through the oxide ion conductive solid electrolyte and fuel, and electric energy and thermal energy are generated. Electric energy is taken out of the SOFC and used for various electrical applications. On the other hand, thermal energy is used to raise the temperature of fuel, SOFC, oxidant and the like.

  In addition, it is known that fuel cells are deteriorated by long-term use. Japanese Unexamined Patent Publication No. 2007-87756 (Patent Document 1) describes a solid oxide fuel cell. In this fuel cell, it is described that the deterioration of the fuel cell is reduced by adjusting the flow rate of the fuel.

  Furthermore, Japanese Unexamined Patent Application Publication No. 2003-217627 (Patent Document 2) describes a fuel supply amount control device, a fuel supply amount control method, and a power supply system. The fuel supply amount control device is configured to compensate the fuel supply amount when the power that can be taken out with respect to the predetermined fuel supply amount is reduced due to deterioration of the fuel cell.

JP 2007-87756 A JP 2003-217627 A

  However, in general, solid electrolyte fuel cells have a large heat capacity, and the response to changes in operating conditions is extremely slow. Therefore, after changing the fuel supply amount, the temperature of the fuel cells rises and is required. It takes a long time of several hours before output power can be supplied. In addition, the output power required for the fuel cell constantly fluctuates, and in a solid oxide fuel cell that varies the output power according to the required power generation, the operating conditions of the fuel cell are constantly changed. ing. For this reason, it can be said that it is extremely difficult to accurately grasp the state of the fuel cell from the output power with respect to the fuel supply amount.

  Furthermore, since the output power of the fuel cell is influenced by a large number of factors such as the outside air temperature, the outside air humidity, and the operation history, which are fluctuation factors for maintaining the high temperature state of the fuel cell, this is the fuel cell. It makes it harder to understand the cell status. For example, if the fuel supply amount is corrected so that fuel cell deterioration is misjudged and more fuel is supplied than is actually required, the excess fuel will be generated. Since it is burned without being used, there is a problem that power generation efficiency is lowered. Furthermore, if the fuel cell deterioration is erroneously determined as a result of continued operation under improper operating conditions, the fuel cell will rise excessively and promote the deterioration of the fuel cell. There is also a problem that it ends up.

  Accordingly, an object of the present invention is to provide a solid oxide fuel cell capable of accurately determining deterioration of a fuel cell module.

  The present invention relates to a solid oxide fuel cell that varies output power according to a required power generation amount, a fuel cell module including a plurality of solid electrolyte fuel cells, and a fuel that supplies fuel to the fuel cell module Supply means; oxidant gas supply means for supplying oxidant gas to the fuel cell module; water supply means for supplying water to the fuel cell module; and fuel supply from the fuel supply means corresponding to the required power generation amount. Control means for changing the amount, and the control means includes a deterioration determination means for determining deterioration of the fuel cell module, and the deterioration determination means is operated when the fuel cell module is operated in a stable operation state. It is characterized by executing deterioration determination.

  In the present invention configured as described above, the control means controls the fuel supply means, the oxidant gas supply means, and the water supply means to supply fuel, oxidant gas, and water to the fuel cell module. Further, the deterioration determination means provided in the control means executes the deterioration determination when the fuel cell module is operated in a stable operation state.

  According to the present invention configured as described above, the deterioration determination unit executes the deterioration determination when the fuel cell module is operated in a stable operation state. It is possible to suppress and accurately determine the deterioration of the fuel cell module.

  In the present invention, it is preferable that the deterioration determination unit executes the deterioration determination when a predetermined deterioration determination fuel supply amount is supplied from the fuel supply unit.

  According to the present invention configured as described above, since the deterioration determination unit performs the deterioration determination when a certain amount of fuel is supplied from the fuel supply unit, the deterioration determination due to the change in the fuel supply amount is adversely affected. Therefore, it is possible to accurately determine the deterioration of the fuel cell module.

  In the present invention, preferably, the deterioration determination means forms a stable operation state of the fuel cell module by supplying a constant fuel supply amount from the fuel supply means regardless of the required power generation amount.

  According to the present invention configured as described above, since the deterioration determination means supplies a constant fuel supply amount from the fuel supply means regardless of the required power generation amount, a stable operation state can be formed as necessary. It is possible to determine deterioration.

In the present invention, it is preferable that the deterioration determination unit performs the deterioration determination after a predetermined deterioration determination fuel supply amount is supplied from the fuel supply unit for a predetermined deterioration determination time.
According to the present invention configured as described above, the fuel supply amount is changed because the deterioration determination is executed after the predetermined deterioration determination fuel supply amount is supplied from the fuel supply means for the predetermined deterioration determination time. It is possible to perform the deterioration determination in which the influence on the operation state is sufficiently eliminated.

  In the present invention, preferably, the deterioration determining means is deteriorated when a predetermined deterioration determining oxidant gas supply amount is supplied from the oxidant gas supplying means and a predetermined deterioration determining water supply amount is supplied from the water supplying means. Make a decision.

  According to the present invention configured as described above, since the deterioration determination is executed in a state where the fuel supply amount, the oxidant gas supply amount, and the water supply amount are also constant, the deterioration determination can be performed more accurately. it can.

In the present invention, it is preferable that the deterioration determination unit executes the deterioration determination when the outside air state is a predetermined deterioration determination outside air state.
According to the present invention configured as described above, since the deterioration determination is executed when the outside air is in a predetermined state, the influence of environmental factors on the deterioration determination can also be suppressed.

In the present invention, preferably, the deterioration determination means forms a stable operation state of the fuel cell module at every predetermined deterioration determination interval, and executes the deterioration determination.
According to the present invention configured as described above, a stable operation state is formed every predetermined period, and deterioration determination is performed, so that a stable operation state is forcibly formed more frequently than necessary. Therefore, the convenience of the fuel cell can be improved.

  In the present invention, preferably, the deterioration determination means determines whether or not the fuel cell module has deteriorated by comparing an operation result in a stable operation state of the fuel cell module with a predetermined deterioration determination reference value.

  According to the present invention configured as described above, since the deterioration is determined by comparing the operation result in the stable operation state with the predetermined deterioration determination reference value, the deterioration can be grasped numerically.

  In the present invention, preferably, the operation result is a temperature or output voltage of the fuel cell module in a stable operation state of the fuel cell module, and is compared with a predetermined deterioration determination reference value.

  According to the present invention configured as described above, since the deterioration is determined based on the temperature or the output voltage of the fuel cell module, the deterioration can be determined without being affected by the amount of power used at the time of determining the deterioration. .

  According to the solid oxide fuel cell of the present invention, it is possible to accurately determine the deterioration of the fuel cell module.

1 is an overall configuration diagram showing a solid oxide fuel cell (SOFC) according to an embodiment of the present invention. 1 is a front sectional view showing a solid oxide fuel cell (SOFC) fuel cell module according to an embodiment of the present invention. FIG. 3 is a sectional view taken along line III-III in FIG. 2. It is a fragmentary sectional view showing a fuel cell unit of a solid oxide fuel cell (SOFC) according to one embodiment of the present invention. 1 is a perspective view showing a fuel cell stack of a solid oxide fuel cell (SOFC) according to an embodiment of the present invention. 1 is a block diagram illustrating a solid oxide fuel cell (SOFC) according to an embodiment of the present invention. It is a time chart which shows the operation | movement at the time of starting of the solid oxide fuel cell (SOFC) by one Embodiment of this invention. It is a time chart which shows the operation | movement at the time of operation stop of the solid oxide fuel cell (SOFC) by one Embodiment of this invention. It is a time chart explaining the deterioration determination in the solid oxide fuel cell by one Embodiment of this invention. It is a graph which shows an example of the relationship between the required electric power generation amount input into a control part, and the fuel supply amount required in order to produce | generate a required electric power generation amount. It is a graph which shows an example of the time change of the fuel supply amount with respect to the change of the required power generation amount. It is a flowchart which shows the procedure of the deterioration determination by a deterioration determination means.

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 sealed space 8 is formed inside the housing 6 via a heat insulating material (not shown, but the heat insulating material is not an essential component and may not be necessary). Is formed. In addition, you may make it not provide a heat insulating material. A fuel cell assembly 12 that performs a power generation reaction with fuel gas and an oxidant (air) is disposed in a power generation chamber 10 that is a lower portion of the sealed space 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 in the sealed space 8 of the fuel cell module 2. In this combustion chamber 18, the remaining fuel gas that has not been used for the power generation reaction and the remaining oxidant (air) ) And combusted to generate exhaust gas.
Further, a reformer 20 for reforming the fuel gas 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. ing. Further, an air heat exchanger 22 for receiving combustion heat and heating air is disposed above 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. The auxiliary unit 4 also includes a gas shut-off valve 32 that shuts off the fuel gas supplied from a fuel supply source 30 such as city gas, a desulfurizer 36 for removing sulfur from the fuel gas, and a flow rate of the fuel gas. A fuel flow rate adjusting 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, in the sealed space 8 in the housing 6 of the fuel cell module 2, as described above, the fuel cell assembly 12, the reformer 20, and the air heat exchange are sequentially performed from below. A vessel 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 addition, in the reformer 20, an evaporation unit 20a and a reforming unit 20b are formed in order from the upstream side, and the reforming unit 20b is 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. The air heat exchanger 22 includes an air aggregation chamber 70 on the upstream side and two air distribution chambers 72 on the downstream side. The air aggregation chamber 70 and the air distribution chamber 72 include six air flow path tubes 74. Connected by. Here, as shown in FIG. 3, three air flow path pipes 74 form a set (74a, 74b, 74c, 74d, 74e, 74f), and the air in the air collecting chamber 70 is in each set. It flows into each air distribution chamber 72 from the air flow path pipe 74.

The air flowing through the six air flow path pipes 74 of the air heat exchanger 22 is preheated by exhaust gas that burns and rises in the combustion chamber 18.
An air introduction pipe 76 is connected to each of the air distribution chambers 72, the air introduction pipe 76 extends downward, and the lower end side communicates with the lower space of the power generation chamber 10, and the air that has been preheated in the power generation chamber 10. Is introduced.

Next, an exhaust gas chamber 78 is formed below the manifold 66. Further, as shown in FIG. 3, an exhaust gas passage 80 extending in the vertical direction is formed inside the front surface 6 a and the rear surface 6 b which are surfaces along the longitudinal direction of the housing 6, and the upper end side of the exhaust gas passage 80 is formed. Is in communication with the space in which the air heat exchanger 22 is disposed, and the lower end side is in communication with the exhaust gas chamber 78. Further, an exhaust gas discharge pipe 82 is connected to substantially the center of the lower surface of the exhaust gas chamber 78, and the downstream end of the exhaust gas discharge pipe 82 is connected to the above-described hot water producing apparatus 50 shown in FIG.
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. 4 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.
As shown in FIG. 4, 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 therein, a cylindrical outer electrode layer 92, an inner electrode layer 90, and an outer side. An electrolyte layer 94 is provided between the electrode layer 92 and the 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 includes, for example, a mixture of Ni and zirconia doped with at least one selected from rare earth elements such as Ca, Y, and Sc, and Ni and ceria doped with at least one selected from rare earth elements. The mixture is formed of at least one of Ni and a mixture of lanthanum garade doped with at least one selected from Sr, Mg, Co, Fe, and Cu.

  The electrolyte layer 94 includes, 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, 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 is formed from at least one of lanthanum cobaltite doped with at least one selected from the group consisting of silver and silver.

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. A 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 an alarm (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 (steam) 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.
Further, the control unit 110 sends a control signal to the inverter 54 to control the power supply amount.

Next, the operation at the time of start-up by the solid oxide fuel cell (SOFC) according to the present embodiment will be described with reference to FIG. FIG. 7 is a time chart showing the operation at the time of startup of the solid oxide fuel cell (SOFC) according to one embodiment of the present invention.
Initially, in order to warm the fuel cell module 2, the operation is started in a no-load state, that is, in a state where a circuit including the fuel cell module 2 is opened. At this time, since no current flows through the circuit, the fuel cell module 2 does not generate power.

First, reforming air is supplied from the reforming air flow rate adjustment unit 44 to the reformer 20 of the fuel cell module 2 via the first heater 46. At the same time, the power generation air is supplied from the power generation air flow rate adjustment unit 45 to the air heat exchanger 22 of the fuel cell module 2 via the second heater 48, and this power generation air is supplied to the power generation chamber 10 and the combustion chamber. Reach chamber 18.
Immediately after this, the fuel gas is also supplied from the fuel flow rate adjustment unit 38, and the fuel gas mixed with the reforming air passes through the reformer 20, the fuel cell stack 14, and the fuel cell unit 16, and It reaches the combustion chamber 18.

  Next, the ignition device 83 is ignited to burn the fuel gas and air (reforming air and power generation air) in the combustion chamber 18. Exhaust gas is generated by the combustion of the fuel gas and air, and the power generation chamber 10 is warmed by the exhaust gas, and when the exhaust gas rises in the sealed space 8 of the fuel cell module 2, The fuel gas containing the reforming air is warmed, and the power generation air in the air heat exchanger 22 is also warmed.

  At this time, the fuel gas mixed with the reforming air is supplied to the reformer 20 by the fuel flow rate adjusting unit 38 and the reforming air flow rate adjusting unit 44. The partial oxidation reforming reaction POX shown in FIG. Since the partial oxidation reforming reaction POX is an exothermic reaction, the startability is good. Further, the heated fuel gas is supplied to the lower side of the fuel cell stack 14 through the fuel gas supply pipe 64, whereby the fuel cell stack 14 is heated from below, and the combustion chamber 18 also has the fuel gas and air. The fuel cell stack 14 is also heated from above, and as a result, the fuel cell stack 14 can be heated substantially uniformly in the vertical direction. Even if the partial oxidation reforming reaction POX proceeds, the combustion reaction between the fuel gas and air continues in the combustion chamber 18.

_{C m H n + xO 2 →} aCO 2 + bCO + cH 2 (1)

  When the reformer temperature sensor 148 detects that the reformer 20 has reached a predetermined temperature (for example, 600 ° C.) after the partial oxidation reforming reaction POX is started, the water flow rate adjustment unit 28 and the fuel flow rate adjustment unit 38 are detected. In addition, the reforming air flow rate adjusting unit 44 supplies a gas in which fuel gas, reforming air, and water vapor are mixed in advance to the reformer 20. At this time, in the reformer 20, an autothermal reforming reaction ATR in which the partial oxidation reforming reaction POX described above and a steam reforming reaction SR described later are used proceeds. Since the autothermal reforming reaction ATR is thermally balanced internally, the reaction proceeds in the reformer 20 in a thermally independent state. That is, when oxygen (air) is large, heat generation by the partial oxidation reforming reaction POX is dominant, and when there is much steam, an endothermic reaction by the steam reforming reaction SR is dominant. At this stage, the initial stage of startup has already passed, and the temperature inside the power generation chamber 10 has been raised to a certain temperature. Therefore, even if the endothermic reaction is dominant, no significant temperature drop is caused. Further, the combustion reaction continues in the combustion chamber 18 even while the autothermal reforming reaction ATR is in progress.

  When the reformer temperature sensor 146 detects that the reformer 20 has reached a predetermined temperature (for example, 700 ° C.) after the start of the autothermal reforming reaction ATR shown in Formula (2), the reforming air flow rate The supply of reforming air by the adjustment unit 44 is stopped, and the supply of water vapor by the water flow rate adjustment unit 28 is increased. As a result, the reformer 20 is supplied with a gas that does not contain air and contains only fuel gas and water vapor, and the steam reforming reaction SR of formula (3) proceeds in the reformer 20.

_{C m H n + xO 2 +} yH 2 O → aCO 2 + bCO + cH 2 (2)
C _m H _n + xH ₂ O → aCO ₂ + bCO + cH ₂ (3)

  Since the steam reforming reaction SR is an endothermic reaction, the reaction proceeds while maintaining a heat balance with the combustion heat from the combustion chamber 18. At this stage, since the fuel cell module 2 is in the final stage of start-up, the power generation chamber 10 is heated to a sufficiently high temperature. Therefore, even if the endothermic reaction proceeds, the power generation chamber 10 is greatly reduced in temperature. There is nothing. Even if the steam reforming reaction SR proceeds, the combustion reaction continues in the combustion chamber 18.

  In this way, after the fuel cell module 2 is ignited by the ignition device 83, the partial oxidation reforming reaction POX, the autothermal reforming reaction ATR, and the steam reforming reaction SR proceed in sequence, so that the inside of the power generation chamber 10 The temperature gradually increases. Next, when the temperature in the power generation chamber 10 and the fuel cell 84 reaches a predetermined power generation temperature lower than the rated temperature at which the fuel cell module 2 is stably operated, the circuit including the fuel cell module 2 is closed, and the fuel cell Power generation by the module 2 is started, so that a current flows in the circuit. Due to the power generation of the fuel cell module 2, the fuel cell 84 itself also generates heat, and the temperature of the fuel cell 84 also rises. As a result, the rated rated temperature at which the fuel cell module 2 is operated becomes, for example, 600 ° C. to 800 ° C.

  Thereafter, in order to maintain the rated temperature, more fuel gas and air than the amount of fuel gas and air consumed in the fuel cell 84 are supplied, and combustion in the combustion chamber 18 is continued. During power generation, power generation proceeds in a steam reforming reaction SR with high reforming efficiency.

Next, the operation when the solid oxide fuel cell (SOFC) according to the present embodiment is stopped will be described with reference to FIG. FIG. 8 is a time chart showing the operation when the solid oxide fuel cell (SOFC) is stopped according to this embodiment.
As shown in FIG. 8, when the operation of the fuel cell module 2 is stopped, first, the fuel flow rate adjustment unit 38 and the water flow rate adjustment unit 28 are operated to supply fuel gas and water vapor to the reformer 20. Reduce the amount.

  Further, when the operation of the fuel cell module 2 is stopped, the amount of fuel gas and water vapor supplied to the reformer 20 is reduced, and at the same time, the fuel cell module for generating air by the reforming air flow rate adjusting unit 44 The supply amount into 2 is increased, the fuel cell assembly 12 and the reformer 20 are cooled by air, and these temperatures are lowered. Thereafter, when the temperature of the power generation chamber decreases to a predetermined temperature, for example, 400 ° C., the supply of fuel gas and steam to the reformer 20 is stopped, and the steam reforming reaction SR of the reformer 20 is ended. This supply of power generation air continues until the temperature of the reformer 20 decreases to a predetermined temperature, for example, 200 ° C., and when this temperature is reached, the power generation air from the power generation air flow rate adjustment unit 45 is supplied. Stop supplying.

  As described above, in the present embodiment, when the operation of the fuel cell module 2 is stopped, the steam reforming reaction SR by the reformer 20 and the cooling by the power generation air are used in combination. The operation of the fuel cell module can be stopped.

  Next, deterioration determination of the fuel cell module 2 will be described with reference to FIGS. FIG. 9 is a time chart for explaining deterioration determination in the solid oxide fuel cell of the present embodiment. FIG. 10 is a graph showing an example of the relationship between the required power generation amount input to the control unit 110 and the fuel supply amount necessary to generate the required power generation amount. FIG. 11 is a graph illustrating an example of a temporal change in the fuel supply amount with respect to a change in the required power generation amount. FIG. 12 is a flowchart showing a procedure of deterioration determination by the deterioration determination means.

  At time t0 to t1 in FIG. 9, the solid oxide fuel cell 1 performs a load following operation so that output power corresponding to the required power generation amount from the inverter 54 (FIG. 6) is obtained. That is, as shown in FIG. 6, the control unit 110 serving as the control unit performs the fuel flow adjustment unit 38 serving as the fuel supply unit and the power generation air serving as the oxidant gas supply unit according to the required power generation amount from the inverter 54. Signals are sent to the flow rate adjusting unit 45 and the water flow rate adjusting unit 28 serving as water supply means, and fuel, air, and water at the required flow rates are supplied to the fuel cell module 2. As a result, as shown in FIG. 9, the output power of the solid oxide fuel cell 1 changes so as to follow the required power generation amount from the inverter 54. Here, there is a delay in the response of the output power to the fuel supply amount, etc., the output power changes with a delay with respect to changes in the fuel supply amount, etc. The power hardly changes.

  The control unit 110 determines the fuel supply amount based on the graph shown in FIG. 10 according to the required power generation amount from the inverter 54, and adjusts the fuel flow rate so that the determined flow rate of fuel is supplied to the fuel cell module 2. The unit 38 is controlled. After the initial use of the solid oxide fuel cell 1 is started, until it is determined that the fuel cell module 2 has deteriorated, the control unit 110 sets the fuel supply amount with respect to the required power generation amount according to the curve F0 in FIG. decide. As shown in FIG. 10, the fuel supply amount is determined so as to increase monotonously with an increase in the required power generation amount. However, the fuel supply amount is set to a substantially constant value when the required power generation amount is less than about 200 W.

  Further, when the required power generation amount is changed, if the fuel supply amount is rapidly changed, the deterioration of the fuel cell module 2 may be accelerated. Therefore, as shown in FIG. 11, the fuel supply amount is gradually increased or gradually decreased. . FIG. 11 is a graph showing an example of a change in the fuel supply amount with respect to time when the required power generation amount is changed in a step shape from 500 W to 700 W. As shown in FIG. 11, when the required power generation amount is changed from 500 W to 700 W at time t10, the required fuel supply amount suddenly changes from the supply amount corresponding to the power output of 500 W to the supply amount corresponding to 700 W. Changed. On the other hand, the control unit 110 controls the fuel flow rate adjustment unit 38 so that the fuel supply amount is gradually increased as shown by an imaginary line in FIG. 11 so that the fuel supply amount does not increase rapidly. Control. The controller 110 increases the fuel supply amount according to the line F10 in FIG. 11 until it is determined that the fuel cell module 2 has deteriorated after the initial use of the solid oxide fuel cell 1 is started.

Similarly, when the required power generation amount is changed from 700 W to 500 W at time t11, the control unit 110 gradually increases the fuel supply amount according to the line F10 in FIG. 11 so that the fuel supply amount does not rapidly decrease. Decrease. Note that the rate of change of the fuel supply amount is set more gently when the supply amount is increased than when the supply amount is decreased.
10 and 11 relate to the fuel supply amount, the air supply amount and the water supply amount are similarly changed according to the required power generation amount.

  Next, at time t1 in FIG. 9, the deterioration determination unit 110a (FIG. 6) built in the control unit 110 starts operation in the deterioration determination mode. The deterioration determining unit 110a includes a microprocessor, a memory, a program (not shown above) for operating these, and the like. FIG. 12 is a flowchart showing a process performed by the deterioration determining unit 110a.

  The flowchart shown in FIG. 12 is executed at predetermined time intervals by the deterioration determination unit 110a. First, in step S1, an elapsed time from the previous operation in the deterioration determination mode is determined. When two weeks, which is a predetermined deterioration determination interval, has not elapsed since the previous deterioration determination mode operation, the process proceeds to step S9, and one process of this flowchart is ended. By this processing, it is possible to prevent the deterioration determination mode operation from being performed unnecessarily frequently and wasting fuel and the like.

  When two weeks or more have passed since the previous deterioration determination mode operation, the process proceeds to step S2 and whether or not the external environment of the solid oxide fuel cell 1 is in a predetermined deterioration determination outside air state suitable for the deterioration determination mode operation. Is judged. Specifically, it is determined whether or not the outside air temperature and the outside air humidity detected by the outside air temperature sensor 150 (FIG. 6) and the outside air humidity sensor (not shown) meet predetermined conditions. In the present embodiment, when the outside air temperature is 5 to 30 ° C. and the outside air humidity is 30 to 70%, it is determined that the external environment is in the deterioration determination outside air state suitable for the deterioration determination mode operation. When it is determined that the external environment is not in the deterioration determination outside air state, the process proceeds to step S9, and the one-time process of this flowchart is ended.

  In this embodiment, the deterioration determination is performed in a cycle of once every two weeks. However, the high frequency means that the deterioration determination mode is forcibly changed without performing load following control. This is a disadvantage in terms of energy saving. Therefore, it is desirable to set according to the degree of performance degradation, and if the degradation is small, the frequency is desirably once every six months. Further, since the deterioration is small if the operation period is short, the frequency is once a year, and it is more desirable to shorten the determination cycle as the operation period becomes longer, such as 5 years or 10 years. Become. In the present embodiment, a very easy-to-understand correspondence is taken as an example.

  When the external environment is suitable for the deterioration determination mode operation, the process proceeds to step S3, and the operation in the deterioration determination mode is started. Further, in step S4, the fuel supply amount, the air supply amount, and the water supply amount are fixed to a fixed supply amount that is a predetermined supply amount. In other words, in the deterioration determination mode operation, the deterioration determination means 110a allows the fuel flow rate adjustment unit 38, the power generation air flow rate adjustment unit 45, and the water flow rate adjustment unit 28 to maintain a constant supply amount regardless of the required power generation amount for the control unit 110. Control these adjustment units to maintain. In the present embodiment, at time t1 in FIG. 9, the deterioration determination fuel supply amount is 3 L / min, the deterioration determination oxidant gas supply amount is 100 L / min, and the deterioration determination water supply amount is 8 mL / min.

  These fixed values of the fuel supply amount, the air supply amount, and the water supply amount are the supply amounts obtained in advance by experiments, assuming that 700 W, which is the rated power generation amount of the solid oxide fuel cell 1 according to the present embodiment, can be generated. Therefore, while fuel, air, and water are supplied at fixed values, the solid oxide fuel cell 1 has the ability to output 700 W of electric power, although there are individual differences in fuel cells. . However, even if the fuel supply amount or the like is fixed, the operating state of the fuel cell module 2 is not sufficiently stable if the electric power extracted from the fuel cell module 2 changes according to the required power generation amount. For this reason, in this embodiment, power is not extracted from the fuel cell module 2 during the deterioration determination mode operation regardless of the required power generation amount (that is, fuel corresponding to the rated power generation amount is supplied, but actually The power generated is 0). Accordingly, during the deterioration determination mode operation, the supplied fuel is not used for power generation but is burned in the combustion chamber 18.

  In the present embodiment, the fixed value such as the fuel supply amount is set to a value corresponding to the rated power generation amount, but these fixed values can be arbitrarily set. Preferably, the fuel cell module 2 is set to a value capable of generating electric power close to the rated power generation amount, in which the fuel cell module 2 can be thermally autonomous and the temperature changes sufficiently greatly depending on the degree of deterioration of the fuel cell module 2. In the present embodiment, power is not extracted from the fuel cell module 2 during the deterioration determination mode operation, but the solid oxide fuel cell 1 is configured so that constant power is extracted during the deterioration determination mode operation. In addition, the operation state of the fuel cell module 2 can be stabilized and the deterioration can be determined. In an environment where the power generated by the solid oxide fuel cell 1 can be sold, it is possible to easily obtain an operation state in which constant power is taken out. Further, by providing the solid oxide fuel cell 1 with a dummy load (not shown) such as a heater for consuming the electric power generated during the operation in the deterioration determination mode, the generated electric power is consumed by this. You may take out fixed electric power.

  Next, in step S5 of FIG. 12, it is determined whether or not a sufficient time has elapsed after the operation with the fixed value is started and a stable operation state has been achieved. In the present embodiment, after the operation with a fixed value is started, a stable operation state is determined based on whether or not 5 hours as the deterioration determination time has elapsed. If 5 hours have not elapsed since the start of operation with a fixed value, the process of step S5 is repeated. Thereby, the driving | operation by the fixed value started in step S4 is maintained over 5 hours (FIG. 9, time t1-t2).

  After the operation with the fixed value is continued for 5 hours, at time t2 in FIG. 9, the process proceeds to step S6, and it is determined whether or not the temperature of the fuel cell module 2 measured by the power generation chamber temperature sensor 142 is equal to or higher than a predetermined temperature. . That is, the temperature of the fuel cell module 2 that is an operation result of operating the fuel cell module 2 in a stable operation state and a reference temperature that is a predetermined deterioration determination reference value (in the state where the fuel cell module 2 is not deteriorated, the rating is The deterioration of the fuel cell module 2 is determined by comparing the ideal stack temperature value to be generated in a stable operation state of 700 W. In the solid oxide fuel cell 1 of the present embodiment, the reference temperature T0 of the fuel cell module 2 when the rated output operation of 700 W is performed in the initial state is about 700 ° C., and the deterioration of the fuel cell module 2 proceeds. This temperature rises. This is because the internal resistance of the fuel cell stack 14 increases due to deterioration of the fuel cell unit 16 itself, which is a solid oxide fuel cell, and deterioration of the contact portion that electrically connects each fuel cell unit 16. This is due to Joule heat and the like.

  In the present embodiment, the deterioration determination unit 110a determines that the fuel cell module 2 has deteriorated when the temperature T1 measured by the power generation chamber temperature sensor 142 is 30 ° C. or more higher than the reference temperature T0. If the fuel cell module 2 has not deteriorated, the process proceeds to step S10, where one process of this flowchart is terminated, and the operating conditions such as the fuel supply amount are not changed.

  When it is determined that the fuel cell module 2 has deteriorated, the process proceeds to step S7, and deterioration processing is started. In step S7, the fuel supply correction is executed, and the fuel supply amount with respect to the required power generation amount and the gain of the fuel supply amount are changed. That is, when it is first determined that the fuel cell module 2 has deteriorated after the use of the solid oxide fuel cell 1 is started, the fuel supply amount with respect to the required power generation amount is changed from the curve F0 of FIG. 10 by the fuel supply correction. After that, the fuel supply amount is determined using the curve F1. Further, the change rate when changing the fuel supply amount is changed from the line F10 in FIG. 11 to a more gradual line F11, and thereafter, the fuel supply amount is changed according to this change rate. The fuel supply amount changed by the fuel supply correction is maintained until it is determined that the fuel cell module 2 is further deteriorated.

  When the fuel cell module 2 deteriorates, the power output for the same fuel supply amount decreases. Therefore, the fuel supply amount is determined according to the curve F1 in which the fuel supply amount is increased by 10% with respect to the curve F0. Then, the decrease in the output power is corrected so as to compensate for the decrease in the output power by increasing the temperature of the fuel cell unit 16. Further, when the fuel supply amount of the deteriorated fuel cell module 2 is rapidly changed, the deterioration is further advanced, so that the rate of change of the fuel supply amount is further reduced.

  When the deterioration is determined again, the fuel supply amount is changed from the curve F1 to the curve F2, and when it is determined again, the fuel supply amount is changed from the curve F2 to the curve F3. The curve F2 is increased by 18% with respect to the curve F0, and the curve F3 is increased by 23% with respect to the curve F0. As described above, when the deterioration is determined for the first time, 10% of the initial fuel supply amount is increased, and for the second time, 8% of the initial fuel supply amount is further increased (18% in total). ) In the third time, 5% of the initial fuel supply amount is increased (a total of 23%). As described above, the fuel supply correction to be executed is set so that the fuel increase becomes smaller as it is executed later. As a result, an excessive burden is prevented from being applied to the fuel cell module 2 that has been deteriorated. Further, the gain of the fuel supply amount is also changed from the line F11 to the line F12 when the deterioration is determined for the second time, and from the line F12 to the line F13 when the deterioration is determined for the third time.

  Thus, in this embodiment, the increment of the fuel supply amount when it is determined that the fuel has deteriorated is set to a preset fixed value. For this reason, for example, unlike the case where the correction amount of the fuel supply amount is calculated based on the temperature rise of the fuel cell module 2 or the correction amount is calculated based on the decrease amount of the output power, a greatly incorrect correction is made. Can be prevented. That is, the temperature and output power of the fuel cell module 2 are affected by various factors and change their values. If abnormal temperature or output power is measured for some reason, correction is made based on these values. If the amount is calculated, an abnormal correction will be performed.

  After the fuel supply amount is corrected, the process proceeds to step S8. In step S8, the temperature T2 of the fuel cell module 2 when the solid oxide fuel cell 1 is operated with the corrected fuel supply amount is the power generation chamber temperature. Measured by sensor 142. The measured temperature T2 is stored in a memory (not shown) of the deterioration determining means 110a as a new reference temperature T0. This new reference temperature T0 is used as a reference temperature in the next deterioration determination. Preferably, after the fuel supply amount is corrected, the operation is performed with the fuel supply amount kept constant for a predetermined time, and then the temperature T2 of the fuel cell module 2 is measured. Thereby, it is possible to measure an accurate temperature from which the influence of the change in the fuel supply amount due to the correction is eliminated.

  When the above deterioration processing is completed, the deterioration determination unit 110a ends the deterioration determination mode operation, and the control unit 110 resumes normal operation corresponding to the required power generation amount (FIG. 9, time t2).

  Furthermore, when the user of the solid oxide fuel cell 1 is using electric power that is equal to or higher than the rated power of the solid oxide fuel cell 1, the required power generation amount sent from the inverter 54 to the control unit 110 is the solid electrolyte. This is the rated power of the fuel cell 1. When such a state is continued for a long time, as a result, the amount of fuel, air, and water supplied to the fuel cell module 2 is a constant value corresponding to the rated power for a long time. (FIG. 9, times t3 to t4).

  The degradation determination unit 110a also performs degradation determination even when such a stable operation state continues for 5 hours or more which is the degradation determination time. That is, the degradation determination unit 110a compares the temperature T1 measured by the power generation chamber temperature sensor 142 with the reference temperature T0 at time t4 in FIG. 9, and determines whether the temperature T1 is 30 ° C. or more higher than the reference temperature T0. Determine whether. When the temperature T1 is higher than the reference temperature T0 by 30 ° C. or more, the deterioration determination unit 110a determines that the deterioration of the fuel cell module 2 has further progressed, and changes the operating conditions so as to correct this deterioration. . When the determination of the deterioration is the second time, the fuel supply amount is changed from the line F1 to the line F2, and the fuel supply amount gain is changed from the line F11 to the line F12.

  However, even if it is determined that the fuel has deteriorated, the correction of the fuel supply amount is not executed if the predetermined minimum correction interval of 0.5 years has not elapsed since the previous fuel supply correction. As a result, excessive fuel supply correction is executed in a short time, and deterioration of the fuel cell module 2 is prevented from proceeding faster than expected.

  Furthermore, at time t5 in FIG. 9, the deterioration determination unit 110a starts the deterioration determination mode operation. In this deterioration determination mode operation, the supply amounts of fuel, air, and water are fixed to the supply amounts corrected by the deterioration determination. That is, when it is determined that the fuel cell module 2 has deteriorated twice in the past, the fuel supply amount determined based on the line F2 in FIG. 10 is fixed to the fuel supply amount corresponding to the rated output.

  The deterioration determination unit 110a measures the temperature T1 of the fuel cell module 2 at time t6 after 5 hours from the start of the deterioration determination mode operation, and executes deterioration determination. Here, when it is determined that the fuel cell module 2 has deteriorated, and this determination of deterioration is the third time, the fuel supply amount is changed from the curve F2 to the curve F3, and the fuel supply amount gain is changed from the line F12 to the line F13. Each will be changed. It should be noted that the deterioration determining unit 110a determines that the deterioration of the fuel cell module 2 is determined when the measured temperature T1 of the fuel cell module 2 exceeds a predetermined correction prohibition temperature of 900 ° C. The fuel supply amount is not corrected.

  When the deterioration further progresses and the fourth deterioration is determined, the deterioration determination unit 110a stops the operation of the solid oxide fuel cell 1 without executing further correction of the fuel supply amount or the like. . That is, the fuel supply correction for correcting the fuel supply amount or the like is executed up to a predetermined correction number of three, and then when it is determined that the fuel cell module 2 has deteriorated, the solid oxide fuel cell 1 Operation is stopped. Moreover, the deterioration determination means 110a sends a signal to the notification device 116 to notify the user that the product life of the solid oxide fuel cell 1 has come. This prevents waste of fuel due to the use of the solid oxide fuel cell 1 that has deteriorated and has reduced power generation efficiency.

  Further, when the output power with respect to a predetermined fuel supply amount set in advance is equal to or lower than the predetermined power, the deterioration determination unit 110a is configured to operate the solid electrolyte fuel even before the fourth deterioration is determined. The operation of the battery 1 is stopped, and the user is notified that the product life has come.

  According to the solid oxide fuel cell of the embodiment of the present invention, the deterioration determination means executes the deterioration determination when the fuel cell module is operated in a stable operation state. The deterioration of the fuel cell module can be accurately determined.

  In addition, according to the solid oxide fuel cell of the present embodiment, the deterioration determination unit performs the deterioration determination when a certain amount of fuel, air, and water is supplied. Adverse effects can be eliminated, and deterioration determination of the fuel cell module can be accurately performed.

  Furthermore, according to the solid oxide fuel cell of the present embodiment, the deterioration determination means supplies a constant amount of fuel, air, and water regardless of the required power generation amount, so that a stable operating state is formed as necessary. Deterioration determination can be performed.

  Further, according to the solid oxide fuel cell of the present embodiment, the deterioration determination is performed after a certain amount of fuel, air, and water are supplied for a predetermined deterioration determination time. It is possible to perform the deterioration determination in which the influence on is sufficiently eliminated.

  Furthermore, according to the solid oxide fuel cell of this embodiment, the deterioration determination is executed when the outside air is in a predetermined state, so that the influence of environmental factors on the deterioration determination can also be suppressed.

  Further, according to the solid oxide fuel cell of the present embodiment, a stable operating state is formed every predetermined period, and deterioration determination is performed, so that a stable operating state is forcibly formed more frequently than necessary. And the convenience of the fuel cell can be improved.

  Furthermore, according to the solid oxide fuel cell of this embodiment, the deterioration is determined by comparing the temperature of the fuel cell module in a stable operation state with the temperature of a predetermined deterioration criterion, so that the deterioration is numerically grasped. can do.

  Further, according to the solid oxide fuel cell of the present embodiment, the deterioration is determined based on the temperature of the fuel cell module, so that the deterioration can be determined without being affected by the amount of power used when determining the deterioration. .

  As mentioned above, although embodiment of this invention was described, a various change can be added to embodiment mentioned above. In particular, in the above-described embodiment, the deterioration determination means uses the temperature of the fuel cell module as the operation result after the operation in the predetermined deterioration determination time and determination mode, and based on this temperature, the presence or absence of deterioration. However, as a modification, the output voltage of the fuel cell module can be used as an operation result, and deterioration can be determined based on this voltage. For example, when the output voltage of an undegraded fuel cell module is 160 V and this voltage drops to 150 V or less, it can be determined that the fuel cell module has deteriorated. The output voltage of the fuel cell module is preferably measured in a state where the current output from the fuel cell module to the inverter is 0, and deterioration is determined based on the voltage. Thereby, it is possible to determine the deterioration without being affected by the amount of power used at the time of determining the deterioration.

  In the above-described embodiment, the deterioration is determined every two weeks as the predetermined deterioration determination interval, but this interval can be arbitrarily changed. Furthermore, the present invention can be configured such that the deterioration determination interval is lengthened at the initial stage when the use of the solid oxide fuel cell is started, and the deterioration determination interval is shortened as the use period becomes longer.

DESCRIPTION OF SYMBOLS 1 Solid oxide type fuel cell 2 Fuel cell module 4 Auxiliary unit 8 Sealed space 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 22 Air heat exchanger 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 Air flow adjustment unit for reforming 45 Air flow adjustment unit for power generation (oxidant gas supply means)
46 1st heater 48 2nd heater 50 Hot water production device 52 Control box 54 Inverter 83 Ignition device 84 Fuel cell 110 Control unit 110a Degradation determination means 112 Operation device 114 Display device 116 Alarm device 126 Power state detection sensor 142 Power generation chamber temperature sensor 150 Outside temperature sensor

Claims (9)

A solid oxide fuel cell that varies the output power according to the required power generation amount,
A fuel cell module comprising a plurality of solid oxide fuel cells,
Fuel supply means for supplying fuel to the fuel cell module;
An oxidant gas supply means for supplying an oxidant gas to the fuel cell module;
Water supply means for supplying water to the fuel cell module;
Control means for changing the amount of fuel supplied from the fuel supply means in response to the required power generation amount,
The control means includes a deterioration determination means for determining deterioration of the fuel cell module,
The deterioration determination means performs a deterioration determination when the fuel cell module is operated in a stable operation state.   2. The solid oxide fuel cell according to claim 1, wherein the deterioration determination unit executes the deterioration determination when a predetermined deterioration determination fuel supply amount is supplied from the fuel supply unit.   3. The solid electrolyte according to claim 1, wherein the deterioration determination unit forms a stable operation state of the fuel cell module by supplying a constant fuel supply amount from the fuel supply unit regardless of a required power generation amount. Type fuel cell.   The solid oxide fuel cell according to claim 2 or 3, wherein the deterioration determination means executes the deterioration determination after the predetermined deterioration determination fuel supply amount is supplied from the fuel supply means for a predetermined deterioration determination time.   The deterioration determination means executes deterioration determination when a predetermined deterioration determination oxidant gas supply amount is supplied from the oxidant gas supply means and a predetermined deterioration determination water supply amount is supplied from the water supply means. The solid oxide fuel cell according to any one of claims 2 to 4.   6. The solid oxide fuel cell according to claim 2, wherein the deterioration determination unit executes the deterioration determination when the outside air is in a predetermined deterioration determination outside air state.   The solid oxide fuel cell according to any one of claims 3 to 6, wherein the deterioration determining means forms a stable operation state of the fuel cell module at predetermined deterioration determination intervals and executes deterioration determination.   8. The fuel cell module according to claim 1, wherein the deterioration determination unit determines whether the fuel cell module has deteriorated by comparing an operation result in a stable operation state of the fuel cell module with a predetermined deterioration determination reference value. 2. A solid oxide fuel cell according to claim 1.   9. The solid oxide fuel cell according to claim 8, wherein the operation result is a temperature or an output voltage of the fuel cell module in a stable operation state of the fuel cell module, and is compared with a predetermined deterioration determination reference value.

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