JP2013235711A - Solid oxide fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid oxide fuel cell that prevents a reduction in power generation efficiency while avoiding the risk of a decrease in internal temperature of a fuel cell module when outside temperature is low.SOLUTION: A solid oxide fuel cell (1) includes: a fuel cell module (2); fuel supply means (38); power generation air supply means (45); a heat storage material (7); an outside air temperature sensor (150) that detects temperature of outside air; and control means (110) that controls the fuel supply means (38) and the power generation air supply means (45) so as to allow the fuel cell module (2) to generate power, while maintaining internal temperature of the fuel cell module (2) within a predetermined temperature range. The control means (110) has: outside air temperature correction means (110a) that, when outside air temperature is low, increases and corrects the amount of fuel to be supplied by the fuel supply means (38) so as to maintain the internal temperature of the fuel cell module (2) within a predetermined temperature range; and correction restriction means (110b) that restricts the increase and correction of the amount of fuel to be supplied, by the outside air temperature correction means (110a) on the basis of predetermined conditions.

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 hydrogen with an oxidant gas.

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

  Japanese Patent Laying-Open No. 2010-80258 (Patent Document 1) describes a fuel cell device. In this fuel cell device, in order to measure the outside air temperature on the exhaust passage for flowing the air in the module storage chamber to the outside of the bottom plate constituting the bottom surface of the auxiliary device storage chamber, and the outer surface of the auxiliary device storage chamber The outside air temperature sensor is provided. The control device controls the opening / closing means for opening and closing the air inlet of the exhaust passage based on the temperature measured by the outside air temperature sensor. This prevents the water supply apparatus from freezing when the outside air temperature is low.

  In addition, since the fuel cell device is a device that generates electric power by reacting power generation air taken into the fuel cell module from the outside air and the fuel gas supplied to the fuel cell module, the outside air temperature is low. In this case, the temperature in the fuel cell module tends to decrease. On the other hand, in the solid oxide fuel cell, it is necessary to maintain the fuel cell at a predetermined temperature or higher in order to generate power. When the maintained temperature is higher than necessary, the fuel cell Unnecessary fuel is consumed to maintain the temperature in the module, and power generation efficiency decreases. For this reason, it is desirable to maintain the temperature in the fuel cell module within a narrow minimum temperature range.

  Thus, in a state where the temperature in the fuel cell module is controlled so as to be maintained in the minimum necessary narrow temperature band, the fuel cell module is caused by the temperature drop of the power generation air taken into the fuel cell module. There is a high risk that the inside temperature falls below the temperature required for power generation. In order to avoid such a risk of temperature decrease in the fuel cell module, when the outside air temperature is low, the supply amount of the fuel gas is corrected to be increased.

JP 2010-80258 A

  However, the present inventor does not necessarily need to correct the fuel increase even when the outside air temperature is low.If the fuel is uniformly increased and corrected according to the outside air temperature, not only the power generation efficiency is reduced, but also in some cases. A new technical problem has been found that the temperature inside the fuel cell module rises excessively. The present invention has been made to solve this problem.

  Accordingly, the present invention provides a solid oxide fuel cell capable of suppressing a decrease in power generation efficiency or an excessive temperature increase while avoiding the risk of a temperature decrease in the fuel cell module when the outside air temperature is low. The purpose is to provide.

  In order to solve the above-described problems, the present invention provides a solid oxide fuel cell that generates power by reacting hydrogen and an oxidant gas, a fuel cell module including a fuel cell stack, and the fuel cell A fuel supply means for supplying fuel to the module; a power supply air supply means for supplying air taken from outside air to the air electrode side of the fuel cell stack; a heat storage material for accumulating heat in the fuel cell module; Control for controlling the outside air temperature sensor for detecting the temperature of the fuel, the fuel supply means, and the air supply means for power generation to cause the fuel cell module to generate electric power while maintaining the temperature in the fuel cell module within a predetermined temperature range Means for maintaining the inside of the fuel cell module in a predetermined temperature range when the outside air temperature detected by the outside air temperature sensor is low. An outside air temperature correcting unit that increases and corrects the fuel supply amount by the fuel supplying unit, and a correction limiting unit that limits the increase correction of the fuel supply amount by the outside air temperature correcting unit based on a predetermined condition. .

  In the present invention configured as described above, fuel is supplied to the fuel cell module including the fuel cell stack by the fuel supply means, and air taken in from the outside air is supplied by the power generation air supply means. The control unit controls the fuel supply unit and the power generation air supply unit to cause the fuel cell module to generate electric power while maintaining the temperature in the fuel cell module in a predetermined temperature range. When the outside air temperature detected by the outside air temperature sensor is low, the outside air temperature correcting means provided in the control means increases the amount of fuel supplied by the fuel supplying means so as to maintain the inside of the fuel cell module within a predetermined temperature range. to correct. In addition, the correction limiting unit provided in the control unit limits the increase correction of the fuel supply amount by the outside air temperature correcting unit based on a predetermined condition.

  In general, a fuel cell module has a very large heat capacity, and its internal temperature changes very slowly. For this reason, even if the control for maintaining the temperature within a predetermined range is started after the temperature in the fuel cell module starts to decrease due to a decrease in the outside air temperature, an excessive temperature decrease in the fuel cell module may not be prevented. For this reason, when the outside air temperature decreases, even if the temperature in the fuel cell module has not started to decrease, the fuel supply amount is corrected to be increased in a preventive manner. However, there are various states of the fuel cell module, and the present invention shows that if the fuel supply amount is uniformly increased and corrected based on the outside air temperature, the operation of the fuel cell module may be adversely affected. Found. That is, depending on the operating state of the fuel cell module, the temperature inside the fuel cell module tends to rise even when the outside air temperature is low. In such a state, if the fuel supply amount is uniformly increased and corrected based on the outside air temperature, not only wasteful fuel is consumed, but the temperature in the fuel cell module rises excessively, and the fuel cell stack May be adversely affected. According to the present invention configured as described above, since the increase correction of the fuel supply amount by the outside air temperature correcting means is limited based on a predetermined condition, the temperature drop in the fuel cell module when the outside air temperature is low is reduced. While avoiding the risk, it is possible to suppress a decrease in power generation efficiency or an excessive temperature rise.

  In the present invention, preferably, the correction limiting unit limits the increase correction of the fuel supply amount by the outside air temperature correcting unit when the drop in the output voltage of the fuel cell module is equal to or less than a predetermined voltage drop amount.

  In a state where the output voltage of the fuel cell module does not drop greatly, sufficient fuel and air for power generation are supplied to the fuel cell stack, and the fuel cell stack has sufficient power generation capability. . According to the present invention configured as described above, in the state where the fuel cell stack has sufficient power generation capability and the risk of temperature decrease is small, the increase correction of the fuel supply amount is limited, so that the waste of fuel is reduced. In addition to being avoided, it is possible to suppress an excessive temperature rise caused by supplying an excessive amount of fuel.

  In the present invention, preferably, it further has a heat storage amount estimation means for estimating the amount of heat accumulated in the fuel cell module, and the correction limiting means has a heat storage amount estimated by the heat storage amount estimation means equal to or greater than a predetermined heat amount. In some cases, the increase correction of the fuel supply amount by the outside air temperature correction means is limited.

  According to the present invention configured as above, since the increase correction of the fuel supply amount is limited when the heat storage amount is equal to or greater than the predetermined heat amount, the fuel is increased in a state where the temperature does not easily decrease. It is possible to avoid waste of fuel and to prevent an excessive increase in temperature of the fuel cell module.

  In the present invention, it is preferable that the correction limiting unit limits the increase correction of the fuel supply amount when the power generated by the fuel cell module is large compared to when the generated power is small.

  In general, the temperature in the fuel cell module increases due to generation of heat generated when the generated power is large, and decreases because the generated heat is small when the generated power is small. Therefore, when the generated power is large, the temperature of the fuel cell module is unlikely to decrease excessively. According to the present invention configured as described above, the fuel supply amount increase correction is greatly limited as the possibility of falling into an excessive temperature drop is low, so fuel consumption is suppressed while avoiding the risk of temperature drop. can do. Further, when the temperature is extremely lowered in some cells of the fuel cell stack, the cells may be damaged by applying a power generation load to the cells. By preventing excessive temperature drop, the risk of such damage can be avoided.

  In the present invention, preferably, the correction limiting unit does not limit the increase correction of the fuel supply amount by the outside air temperature correcting unit when the power generated by the fuel cell module is equal to or less than a predetermined correction execution power.

  According to the present invention configured as described above, when the generated power is equal to or less than the correction execution power and the temperature in the fuel cell module is relatively low, the fuel supply amount increase correction is always executed. It is possible to reliably prevent an excessive temperature drop while avoiding the risk of an excessive temperature rise.

  In the present invention, it is preferable that the outside air temperature correction means performs a decrease correction of the air supply amount by the power generation air supply means when the outside air temperature detected by the outside air temperature sensor is low, and the correction restriction means There is no restriction on the supply amount reduction correction.

  According to the present invention configured as described above, since the air supply amount reduction correction is always performed when the outside air temperature is low, it is possible to reliably reduce the influence of the outside air temperature reduction without wasting fuel. it can.

  According to the solid oxide fuel cell of the present invention, it is possible to suppress a decrease in power generation efficiency or an excessive temperature increase while avoiding the risk of a temperature decrease in the fuel cell module when the outside air temperature is low. it can.

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 fragmentary sectional view showing a fuel cell unit of a fuel cell device by one embodiment of the present 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. It is a time chart which shows the operation | movement at the time of starting of the fuel cell apparatus by one Embodiment of this invention. It is a time chart which shows the operation | movement at the time of the stop of the fuel cell apparatus by one Embodiment of this invention. It is the graph which showed typically the relation of the change of demand electric power, the amount of fuel supply, and the current actually taken out from a fuel cell module. It is a flowchart of the external temperature correction control in the embodiment of the present invention. It is a figure which shows the correction coefficient of the fuel supply amount with respect to external temperature. It is a figure which shows the correction coefficient of the air supply amount for electric power generation with respect to external temperature.

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 7. A fuel cell assembly 12 that performs a power generation reaction with fuel and 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, 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, 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 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. 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 of the exhaust gas chamber passage 80 is formed. The side communicates with the space in which the air heat exchanger 22 is disposed, and the lower end side communicates 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 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 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, 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. 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 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 start-up of the solid oxide fuel cell (SOFC) according to the 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 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 operation of 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 reformer 20 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, control of the solid oxide fuel cell 1 according to the embodiment of the present invention will be described with reference to FIGS. 9 to 12.
FIG. 9 is a graph schematically showing the relationship between the change in power demand, the amount of fuel supplied, and the current actually taken from the fuel cell module.

  As shown in FIG. 9, the fuel cell module 2 is controlled so as to be able to generate power corresponding to the demand power shown in the uppermost stage of FIG. The control unit 110 serving as a control unit sets a fuel supply current value If, which is a target current to be generated by the fuel cell module 2, based on the demand power as shown in the second graph of FIG. Although the fuel supply current value If is set so as to substantially follow the change in demand power, the response speed of the fuel cell module 2 is extremely slow with respect to the change in demand power. It is set so as to follow the demand power gently without following the change. In addition, when the demand power exceeds the rated generated power of the solid oxide fuel cell, the fuel supply current value If follows the current value corresponding to the rated generated power and is set to a current value higher than that. There is no.

  As shown in the third graph of FIG. 9, the control unit 110 controls the fuel flow rate adjustment unit 38, which is a fuel supply unit, so as to generate a fuel supply amount at a flow rate that can generate electric power corresponding to the fuel supply current value If. Fr is supplied to the fuel cell module 2. If the fuel utilization rate, which is the ratio of the fuel actually used for power generation with respect to the fuel supply amount, is constant, the fuel supply current value If and the fuel supply amount Fr are proportional. In the graph of FIG. 9, the fuel supply current value If and the fuel supply amount Fr are drawn as being proportional to each other, but actually, the fuel utilization rate is changed according to the operating state.

  Further, as shown in the lowermost graph in FIG. 9, the control unit 110 outputs a signal that instructs the inverter 54 about the extractable current Iinv that is a current value that can be extracted from the fuel cell module 2. The inverter 54 extracts current (electric power) from the fuel cell module 2 within the range of the extractable current Iinv according to the demand power that changes suddenly every moment. The portion where the demand power exceeds the extractable current Iinv is supplied from the grid power, and this is the purchased power. Here, as shown in FIG. 9, when the current tends to increase, the extractable current Iinv instructed by the control unit 110 to the inverter 54 changes so as to be delayed by a predetermined time with respect to the change in the fuel supply amount Fr. Is set. For example, at time t10 in FIG. 9, after the fuel supply current value If and the fuel supply amount Fr start to increase, the increase of the extractable current Iinv is started with a delay. Also at time t12, after the fuel supply current value If and the fuel supply amount Fr increase, the increase of the extractable current Iinv is started with a delay. In this way, after increasing the fuel supply amount Fr, the timing for actually increasing the electric power extracted from the fuel cell module 2 is delayed.

  As a result, the fuel supplied to the fuel cell module 2 is reformed in the reformer 20, and then the reformed fuel flows into the manifold 66 that is a dispersion chamber, and each fuel constituting the fuel cell stack 14. A time delay until the battery cell unit 16 is distributed is dealt with. Further, it takes time until the actual power generation reaction becomes possible after the fuel is distributed to each fuel cell unit 16, and the timing for increasing the electric power is set in consideration of this time. This reliably prevents the fuel battery cell unit 16 from being depleted of fuel and damaging the fuel battery cell unit 16. FIG. 9 shows macroscopically and schematically the timing of the increase in the fuel supply amount Fr and the increase in the extractable current Iinv.

  Further, as described above, the remaining fuel that is supplied to each fuel cell unit 16 and is not used for power generation flows out from the upper end of each fuel cell unit 16 and is burned there by power generation air. . This combustion heat heats the reformer 20 disposed above the fuel cell stack 14 and heats the inside of the fuel cell module 2. Moreover, the heat insulating material 7 which is a heat storage material is arrange | positioned inside the fuel cell module 2, and the dissipation to the external air of the heat in the fuel cell module 2 is suppressed. Since the heat insulating material 7 has a very large heat capacity, a large amount of heat generated inside during operation of the fuel cell module 2 is accumulated in the heat insulating material 7.

  Therefore, as described with reference to FIG. 9, when the fuel supply amount Fr is increased and then the extractable current Iinv is increased with a predetermined time delay, the fuel supplied during this time is used for power generation. Instead, it is burned at the upper end of each fuel cell unit 16 and used for heating in the fuel cell module 2. Further, the combustion heat generated in this way is accumulated in the heat insulating material 7 in the fuel cell module 2. Thus, when the generated power is frequently changed and the fuel supply amount is repeatedly increased and decreased, the remaining fuel that remains without being used for power generation increases, which heats the inside of the fuel cell module 2, so that the fuel cell module 2 The temperature inside increases.

  On the other hand, each fuel cell unit 16 generates power generation heat when generating electric power (current). For this reason, when the power generated by the fuel cell stack 14 is large, the inside of the fuel cell module 2 is also heated by the generated heat, and when the generated power is small, the heating by the generated heat is also reduced. In order to compensate for this decrease in generated heat, in this embodiment, when the generated power is small, the fuel utilization rate, which is the ratio of the fuel used for power generation out of the supplied fuel, is reduced. The fuel supply amount is set. That is, by setting the fuel utilization rate low, the residual fuel that is not used for power generation increases, and the residual fuel is combusted to heat the inside of the fuel cell module 2 to compensate for the decrease in generated heat. The

  In general, the power generation capacity of the fuel cell stack 14 tends to increase as the temperature rises within a predetermined temperature range. For this reason, in this embodiment, when generating 700 W of maximum rated power, the temperature of the fuel cell stack 14 is higher than when generating about 200 W of low power. In addition, the fuel supply amount is controlled. Therefore, when the generated power is low, the temperature of the fuel cell stack 14 is maintained near the minimum temperature at which power generation is possible, and when the generated power is large, the temperature is higher than the minimum temperature. The fuel supply amount is controlled.

  Further, when the output current is increased in the fuel cell module 2 in order to extract a large amount of electric power to the inverter 54, the output voltage generally tends to decrease. For this reason, when the electric power generated by the fuel cell module 2 increases, the output voltage of the fuel cell module 2 tends to decrease. Further, when the temperature of the fuel cell stack 14 is lower than the temperature commensurate with the generated power, when the fuel cell unit 16 is not supplied with sufficient fuel for the generated power, each fuel cell unit 16 changes over time. In the case of deterioration due to the like, there is a tendency that the reduction rate of the output voltage with respect to the increase of the output current becomes large. That is, when power is taken out in a state where the power generation capacity of the fuel cell stack 14 is not sufficient, the output voltage is significantly reduced with respect to the increase in output current.

Next, with reference to FIGS. 10 to 12, the correction control based on the outside air temperature in the solid oxide fuel cell 1 of the embodiment of the present invention will be specifically described.
FIG. 10 is a flowchart of the outside air temperature correction control in the present embodiment. FIG. 11 is a diagram illustrating a correction coefficient of the fuel supply amount with respect to the outside air temperature. FIG. 12 is a diagram illustrating a correction coefficient of the power generation air supply amount with respect to the outside air temperature.

  The flowchart shown in FIG. 10 is a subroutine for outside temperature correction control for correcting the fuel supply amount and the power generation air supply amount according to the outside air temperature, and is a control means during the operation of the solid oxide fuel cell 1. It is executed by the control unit 110 at predetermined time intervals. Note that the outside air temperature correction control according to FIG. 10 is intended to prevent the fuel cell module 2 from falling excessively when the outside air temperature decreases. That is, the fuel cell module 2 has an extremely large heat capacity, and the temperature change is very slow. Even if the temperature control is started after the temperature decrease of the fuel cell module 2 is detected due to a decrease in the outside air temperature, an excessive temperature In some cases, the decline cannot be prevented. For this reason, when the outside air temperature falls below a predetermined temperature, the outside air temperature correction control is executed even when the temperature inside the fuel cell module 2 is not actually lowered. When the temperature in the fuel cell module 2 actually starts to decrease, temperature control is performed separately from the outside air temperature correction control.

  First, in step S1 of FIG. 10, it is determined whether or not the temperature of the outside air detected by the outside air temperature sensor 150 is −5 ° C. or lower. When the temperature of the outside air is −5 ° C. or lower, the process proceeds to step S2, and when the temperature of the outside air is higher than −5 ° C., one process of the flowchart of FIG. That is, when the temperature of the outside air is higher than −5 ° C., even when the power generation air is taken into the fuel cell module 2 from the outside air, the influence on the temperature inside the fuel cell module 2 is relatively small. The outside air temperature correction control after step S2 is not executed.

  Next, in step S2, it is determined whether the power generated by the fuel cell module 2 is 300 W or less. If the generated power is 300 W or less, which is the corrected execution power, the process proceeds to step S3. If the generated power is greater than the corrected execution power, the process proceeds to step S4.

  In step S3, the fuel supply amount and the power generation air supply amount are corrected by the outside air temperature correction means 110a (FIG. 6) built in the control unit 110. As described above, the temperature of the fuel cell stack 14 is controlled to be relatively high when the generated power is large, while the temperature of the fuel cell stack 14 is decreased when the generated power is small. Since power generation is possible even in a low state, the temperature is controlled to be relatively low. That is, when the generated power is equal to or less than the corrected execution power, the temperature of the fuel cell stack 14 is kept low, so that if the temperature in the fuel cell module 2 decreases due to a decrease in the outside air temperature, the fuel cell There is a possibility that the cell stack 14 will drop below the temperature at which it can generate electricity. For this reason, when the generated power is equal to or less than the correction execution power, the correction by the outside air temperature correction unit 110a is executed as it is, and the correction limitation by the correction limiting unit 110b (FIG. 6) built in the control unit 110 is not executed. .

Specifically, the correction by the outside air temperature correction means 110a is performed by the correction coefficient shown in FIGS.
As shown in FIG. 11, in this embodiment, the fuel supply amount correction coefficient is 1.2 when the outside air temperature is higher than −15 ° C. and lower than −5 ° C., and higher than −25 ° C. and −15 ° C. In the following cases, it is set to 1.4, and in the case of −25 ° C. or lower, it is set to 1.6. The fuel cell module 2 is supplied with an amount of fuel obtained by multiplying the fuel supply amount (FIG. 9) set according to the generated power by a fuel supply amount correction coefficient. As described above, the fuel supply amount is greatly increased as the outside air temperature is lowered. As a result, the residual fuel that is not used for power generation increases, and the fuel cell module 2 is heated by the combustion heat of the residual fuel. Therefore, a decrease in the temperature inside the fuel cell module 2 due to a decrease in the outside air temperature is compensated.

  Also, as shown in FIG. 12, in this embodiment, the power generation air supply amount correction coefficient is 0.8 or -25 ° C. when the outside air temperature is higher than −15 ° C. and lower than −5 ° C. When the temperature is -15 ° C. or lower, 0.6 is set, and when the temperature is −25 ° C. or lower, 0.4 is set. The fuel cell module 2 is supplied with an amount of air obtained by multiplying the power generation air supply amount set according to the generated power by the power generation air supply amount correction coefficient. As described above, since the amount of power generation air supplied is greatly reduced as the outside air temperature is lowered, the flow rate of the air that takes heat away from the inside of the fuel cell module 2 is decreased. A decrease in internal temperature is suppressed. Note that the power generation air supply amount before being multiplied by the power generation air supply amount correction coefficient is set sufficiently larger than the amount of air used for power generation, so by reducing the power generation air supply amount, There is no shortage of air for power generation.

  Thus, in the process in step S3 executed when the outside air temperature is low and the generated power is small, both the fuel supply amount increase correction and the power generation air supply amount decrease correction by the outside air temperature correction means 110a are executed. Thus, the correction limitation by the correction limitation unit 110b is not executed.

  On the other hand, when the generated power is larger than the corrected execution power, step S4 is executed. In step S4, it is determined whether or not the drop in the output voltage of the fuel cell module 2 is equal to or higher than a predetermined voltage. As described above, the output voltage of the fuel cell module 2 decreases as the output current increases. The control unit 110 stores the relationship between the output current and the output voltage when the fuel cell module 2 is generating power in an appropriate state. In step S <b> 4, it is determined whether or not the output voltage detected with respect to the output current of the fuel cell module 2 is lower than the output voltage stored in the control unit 110. If the detected output voltage has dropped to 70% or less of the appropriate stored output voltage, the process proceeds to step S5, and if it has not dropped to 70% or less, the process proceeds to step S6. move on.

  In step S6, based on the power generation air supply amount correction coefficient shown in FIG. 12, only the decrease correction of the power generation air supply amount is executed by the outside air temperature correction means 110a, and the fuel supply amount increase correction is not executed. That is, the increase correction of the fuel supply amount is limited by the correction limiting unit 110b and stopped when the drop in the output voltage of the fuel cell module 2 is equal to or less than the predetermined voltage drop amount. As described above, even when the outside air temperature is lowered, if the output voltage of the fuel cell module 2 is not significantly lowered, it is considered that the fuel cell stack 14 has sufficient power generation capability. The increase correction of the fuel supply amount by the outside air temperature correction means 110a is restricted by the correction restriction means 110b, and the fuel consumption is suppressed.

  On the other hand, in step S5, it is determined whether the estimated heat storage amount estimated to be stored in the fuel cell module 2 is equal to or greater than a predetermined heat amount. As described above, the heat insulating material 7 and the like are accommodated in the fuel cell module 2, and the fuel cell module 2 has a very large heat capacity. Accordingly, after the fuel cell module 2 has been operated for a long time at a high temperature, an extremely large amount of heat is accumulated in the fuel cell module 2, and the temperature of the fuel cell module 2 is unlikely to decrease. On the contrary, after the fuel cell module 2 has been operated for a long time at a low temperature, the temperature rapidly rises when the temperature inside the fuel cell module 2 detected by the power generation chamber temperature sensor 142 is high. However, since the amount of accumulated heat is small, the temperature may drop in a relatively short time.

  The heat storage amount estimation means 110 c (FIG. 6) built in the control unit 110 estimates the amount of heat accumulated in the fuel cell module 2 based on the temperature history detected by the power generation chamber temperature sensor 142. It is configured. In Step S5 of FIG. 10, when the heat storage amount estimated by the heat storage amount estimation means 110c is equal to or greater than the predetermined heat amount, the process proceeds to Step S6, and when it is less than the predetermined heat amount, the process proceeds to Step S3. That is, when the amount of heat stored in the fuel cell module 2 is large, the fuel cell module 2 is in a state in which it does not easily fall into an excessive temperature drop. The increase correction of the fuel supply amount is limited by the correction limiting means 110b. On the other hand, when the amount of heat stored in the fuel cell module 2 is small, the fuel cell module 2 is likely to fall into an excessive temperature drop. Therefore, the correction limitation by the correction limiting unit 110b is not performed, and the power generation air The supply amount decrease correction and the fuel supply amount increase correction are executed.

As described above, in the outside air temperature correction control shown in FIG. 10, when the outside air temperature is low (−5 ° C. or lower), the power generation air supply amount is always corrected to be reduced. There are no restrictions on weight loss correction.
According to the solid oxide fuel cell 1 of the embodiment of the present invention, the increase correction of the fuel supply amount by the outside air temperature correction means 110a is limited by correction based on predetermined conditions (steps S2, S4 and S5 in FIG. 10). Since it is limited by the means 110b, it is possible to suppress a decrease in power generation efficiency or an excessive temperature increase while avoiding the risk of a temperature decrease in the fuel cell module 2 when the outside air temperature is low.

  Further, according to the solid oxide fuel cell 1 of the present embodiment, in a state where the drop in output voltage is small, the fuel cell stack 14 has sufficient power generation capability, and the risk of temperature decrease is low (step of FIG. 10). S4 → S6) Since the increase correction of the fuel supply amount is limited by the correction limiting means 110b, waste of fuel can be avoided and an excessive temperature rise caused by supplying an excessive amount of fuel can be suppressed.

  Furthermore, according to the solid oxide fuel cell 1 of the present embodiment, when the heat storage amount estimated by the heat storage amount estimation unit 110c is equal to or greater than a predetermined heat amount (steps S5 to S6 in FIG. 10), the fuel supply amount is increased. Since the correction is limited by the correction limiting means 110b, it is possible to avoid waste of fuel due to an increase in fuel and prevent an excessive increase in temperature of the fuel cell module 2 in a state where the temperature does not easily decrease. it can.

  Further, according to the solid oxide fuel cell 1 of the present embodiment, when the generated power is equal to or lower than the corrected execution power and the temperature in the fuel cell module 2 is relatively low, the fuel supply by the outside air temperature correction means 110a is performed. Since the amount increase correction is always executed (steps S2 to S3 in FIG. 10), it is possible to reliably prevent an excessive temperature decrease while avoiding the risk of an excessive temperature increase.

  Furthermore, according to the solid oxide fuel cell 1 of the present embodiment, when the outside air temperature detected by the outside air temperature sensor 150 is low, the air supply amount reduction correction is always performed by the outside air temperature correcting unit 110a (see FIG. 10 steps S3 and S6), it is possible to reliably reduce the influence of a decrease in outside air temperature without wasting fuel.

As mentioned above, although preferable embodiment of this invention was described, a various change can be added to embodiment mentioned above.
In particular, in the above-described embodiment, when the generated power is equal to or less than the predetermined correction execution power (step S2 → S3 in FIG. 10), the limitation by the correction limiting unit 110b is not always performed. The degree of correction limitation can be changed according to the magnitude of the generated power. For example, when the power generated by the fuel cell module 2 is large, the fuel increase correction amount is greatly limited and decreased. When the power generated is small, the correction is performed so that the fuel increase correction amount increases without being limited much. The limiting means 110b can also be configured. That is, when the generated power is large, the present invention can be configured such that the increase correction of the fuel supply amount is greatly limited as compared with the case where the generated power is small. According to this modification, since the increase correction of the fuel supply amount is significantly limited in a state where the possibility of falling into an excessive temperature drop is low, fuel consumption can be suppressed while avoiding the risk of temperature drop.

DESCRIPTION OF SYMBOLS 1 Solid oxide fuel cell 2 Fuel cell module 4 Auxiliary machine unit 7 Heat insulation material (heat storage material)
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 (combustion section)
20 Reformer 22 Heat exchanger for air 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 adjustment unit 45 Power generation air flow rate adjustment unit (power generation oxidizing gas supply means)
46 1st heater 48 2nd heater 50 Hot water production device 52 Control box 54 Inverter 66 Manifold (distribution chamber)
76 Air introduction pipe 76a Air outlet 83 Ignition device 84 Fuel cell 110 Control section (control means)
110a Outside air temperature correction means 110b Correction restriction means 110c Heat storage amount estimation means 112 Operation device 114 Display device 116 Alarm device 126 Power state detection sensor (power purchase detection means)
132 Fuel flow sensor (fuel supply detection sensor)
138 Pressure sensor (reformer pressure sensor)
140 Exhaust temperature sensor 142 Power generation chamber temperature sensor (temperature detection means)
148 Reformer temperature sensor (temperature detection means)
150 Outside temperature sensor

Claims (6)

A solid oxide fuel cell that generates electricity by reacting hydrogen with an oxidant gas,
A fuel cell module having a fuel cell stack; and
Fuel supply means for supplying fuel to the fuel cell module;
A power generation air supply means for supplying air taken from outside air to the air electrode side of the fuel cell stack,
A heat storage material for accumulating heat in the fuel cell module;
An outside air temperature sensor for detecting the outside air temperature;
Control means for controlling the fuel supply means and the power generation air supply means to cause the fuel cell module to generate electric power while maintaining the temperature in the fuel cell module in a predetermined temperature range. ,
When the outside air temperature detected by the outside air temperature sensor is low, the control means increases the fuel supply amount by the fuel supply means so as to maintain the inside of the fuel cell module in a predetermined temperature range. A solid oxide fuel cell, comprising: a correction unit; and a correction limiting unit that limits the increase correction of the fuel supply amount by the outside air temperature correction unit based on a predetermined condition.   2. The solid oxidation according to claim 1, wherein the correction limiting means limits the increase correction of the fuel supply amount by the outside air temperature correcting means when the drop in the output voltage of the fuel cell module is not more than a predetermined voltage drop amount. Physical fuel cell.   Furthermore, it has a heat storage amount estimation means for estimating the amount of heat stored in the fuel cell module, and the correction limiting means, when the heat storage amount estimated by the heat storage amount estimation means is a predetermined heat amount or more, 2. The solid oxide fuel cell according to claim 1, wherein the increase correction of the fuel supply amount by the outside air temperature correction means is limited.   2. The solid oxide fuel cell according to claim 1, wherein when the power generated by the fuel cell module is large, the correction limiting means limits the increase correction of the fuel supply amount to a greater extent than when the power generated is small.   5. The solid oxide according to claim 4, wherein the correction limiting means does not limit the increase correction of the fuel supply amount by the outside air temperature correcting means when the power generated by the fuel cell module is equal to or less than a predetermined correction execution power. Type fuel cell.   When the outside air temperature detected by the outside air temperature sensor is low, the outside air temperature correction means performs a decrease correction of the air supply amount by the power generation air supply means, and the correction restriction means 2. The solid oxide fuel cell according to claim 1, wherein no limitation is imposed on the weight loss correction.

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