JP2015197957A - solid oxide fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid oxide fuel cell capable of preventing an excessive temperature rise while increasing total energy efficiency.SOLUTION: A solid oxide fuel cell (1) comprises: a fuel cell module (2); fuel supply means (38); oxidant gas supply means (45) for first power generation; a combustion unit (18) in which residual fuel is combusted; a heat exchange unit (48) for rising the temperature of an oxidant gas for first power generation; and control means (110). The control means comprises excessive temperature rise estimation means and forced cooling means. The forced cooling means lowers the temperature of the fuel cell module (2) by supplying an oxidant gas for second power generation to the fuel cell module (2) in a state in which the temperature of the oxidant gas for second power generation is lower than the temperature of the oxidant gas for first power generation using air for power generation and cooling via a bypass passage (77) for bypassing the heat exchange unit (22).

Description

  The present invention relates to a solid oxide fuel cell, and more particularly to a countermeasure against overheating that can efficiently suppress overheating that occurs in a module during power generation operation.

  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.

  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, reformer, water, oxidant and the like.

  Japanese Patent Laying-Open No. 2012-216290 (Patent Document 1) describes a general operation method when the load of a fuel cell system is increased. In a general operation method of a fuel cell system, when increasing the power generation amount, first, the air supply amount to the fuel cell is increased, and then the supply amount is increased in the order of the water supply amount and the fuel supply amount. After that, the electric power taken out from the fuel cell is increased. In the operation method of this fuel cell system, the supply amount is increased in this order to prevent the occurrence of air depletion, carbon deposition, and fuel depletion.

  Furthermore, in general, a solid oxide fuel cell has a high operating temperature, and it is necessary to maintain the fuel cell at a high operating temperature during power generation. Therefore, in order to increase the overall energy efficiency of the fuel cell system, it is important to reduce the heat dissipated from the fuel cell to the outside air and reduce the fuel required to maintain the temperature. Become. For this reason, it is preferable to store a fuel battery cell etc. in a housing | casing with high heat insulation.

  When the heat insulation of the housing for storing the fuel cells and the like is increased, the heat insulation performance to maintain the temperature in the housing which is supplied to the fuel cells and increased by the remaining fuel that is not used for power generation is maintained. Therefore, the amount of input heat can be reduced and the fuel efficiency can be increased. However, in a situation where the residual fuel becomes surplus or a situation where the amount of heat generation has increased due to deterioration, there arises a problem that the temperature inside the housing is too high outside the temperature range suitable for power generation. If the temperature in the casing rises excessively, the fuel cell in the casing, the reformer, etc. may be damaged. In addition, the excessively increased temperature is not easy to reduce to an appropriate temperature because the heat insulating property of the housing is high and the heat capacity is extremely large, and further excessive temperature rise is caused.

  In Patent Document 1, when such an excessive temperature rise occurs, the excessive temperature increase is prevented by cooling the internal temperature of the module using the increased amount of air increased beyond the supply amount necessary for power generation. Is disclosed.

JP 2012-216290 A

  By increasing the air supply amount, the temperature of the air supplied to the fuel cell is lowered, so that the temperature in the module can be cooled. However, according to this method, in order to increase the cooling amount, it is necessary to increase the air supply amount. However, if the air supply amount is increased too much, the internal pressure of the module increases, and it becomes difficult for fuel gas to enter the module, resulting in fuel depletion. There is a concern to cause. In addition, the increase in air supply volume is limited by the performance of the blower used, and in order to respond to excessive overheating, it is necessary to supply air for power generation. It is necessary to have an excess spec blower that can do. Further, even if an excessive specification blower is provided, there is a limit to the excessive temperature rise that can be dealt with. Therefore, a technique for improving the amount of temperature decrease regardless of the blower performance is desired.

  Accordingly, the present invention provides a solid oxide fuel cell capable of preventing an excessive temperature rise without causing fuel depletion or using an excessive specification device while improving overall energy efficiency. It is intended to provide.

  In order to solve the above-described problems, the present invention uses a supplied fuel and oxidant gas to generate a power generation reaction in a fuel battery cell, and uses the fuel cell module for power generation. Fuel supply means for supplying fuel, first oxidant gas supply means for power generation for supplying first oxidant gas used for power generation from the oxidant gas supply source to the fuel cell module, and fuel supplied by the fuel supply means Among these, the combustion part that heats the fuel cell module by burning the remaining fuel that is not used for power generation, and the first oxidant gas supply means for power generation, the exhaust gas generated in the combustion part and the first In a solid oxide fuel cell device, comprising: a heat exchanging unit that exchanges heat with an oxidant gas for power generation; and a control unit that controls the fuel supply unit and the first oxidant gas supply unit for power generation. And a second power generation oxidant gas supply means for supplying a second power generation oxidant gas used for power generation from the oxidant gas supply source to the fuel cell module, and the control means includes an excessive temperature in the fuel cell module. An excessive temperature rise estimation means for estimating the occurrence of the rise, and when the occurrence of an excessive temperature rise is estimated by the excess temperature rise estimation means, the second power generating oxidant gas is caused to flow into the fuel cell module, thereby Forcibly cooling means for lowering the temperature in the battery module, and the second power generation oxidant gas supply means is configured such that the temperature of the second power generation oxidant gas is lower than that of the first power generation oxidant gas. The second power generation oxidant gas is configured to flow into the fuel cell module by bypassing at least a part of the heat exchange section.

  In the present invention configured as described above, the fuel supply means, the first power generation oxidant gas supply means, and the second power generation oxidant gas supply means are used to generate power using fuel cells. The fuel, the first power generation oxidant gas, and the second power generation oxidant gas are supplied to the battery module, respectively. The fuel cell module generates power using the supplied fuel, the first power generation oxidant gas and the second power generation oxidant gas, and the remaining fuel not used for power generation is burned in the combustion section, Is heated. Further, the exhaust gas generated by the combustion is used to raise the temperature of the power generation oxidant gas by heat exchange with the first power generation oxidant gas upstream of the fuel cell module. The control means controls the fuel supply means based on the demand power detected by the demand power detection means. When excessive temperature rise occurs, it is determined that there is a risk of overheating by the overheating temperature estimation means provided in the control means, and the second power generation oxidant gas having a temperature lower than that of the first power generation oxidant gas. Is forced to flow into the fuel cell module to activate the forced cooling means for lowering the temperature in the fuel cell module.

  According to the solid oxide fuel cell of the present invention, when the forced cooling means supplies the second power generation oxidant gas to the fuel cell module, the second power generation oxidant gas is supplied so as to bypass the heat exchange section. Thus, the temperature of the second power generation oxidant gas introduced from the same oxidant gas supply source as that of the first power generation oxidant gas is made lower than that of the first power generation oxidant gas. Since the temperature in the fuel cell module is lowered by allowing the second power generating oxidant gas to flow into the fuel cell module, the fuel cell can be increased by increasing the supply amount of the first power generating oxidant gas as in the conventional case. Compared to the case of cooling the inside of the module, an excessive temperature rise can be effectively avoided with a small flow rate. Therefore, the amount of the first power generation oxidant gas is increased, the pressure in the fuel cell module is increased, and it is possible to prevent fuel depletion caused by the fuel gas becoming difficult to enter the fuel cell module. Moreover, it is not necessary to install a blower having an excessive specification, which is preferable.

  As described above, the problem of excessive temperature rise can be solved by supplying the second power generation oxidant gas, but if the second power generation oxidant gas having a low temperature is directly applied to the fuel cell, The portion directly hit by the oxidant gas for second power generation is cooled too much as compared with the portion not directly hit, and the portion directly hit by the oxidant gas for second power generation and the portion not hit directly. There is a concern that a difference in thermal expansion occurs due to a temperature difference, and stress is applied to damage the fuel cell.

Therefore, in the present invention, it is preferable to have a temperature raising means for raising the temperature of the bypassed second power generation oxidant gas before supplying the second power generation oxidant gas to the fuel cell module.
According to the present invention configured as described above, it is possible to prevent the second power generating oxidant gas having a low temperature from directly hitting the fuel cell. As a result, it is also possible to suppress the occurrence of a temperature difference between the portions of the fuel battery cells, so that the fuel battery cells can be prevented from being damaged while the temperature of the fuel battery module is lowered.

Further, in the present invention, the temperature raising means mixes the bypassed second power generation oxidant gas and the first power generation oxidant gas before supplying the second power generation oxidant gas to the fuel cell module. It is preferable to provide a part.
According to the present invention thus configured, the second power generation oxidant gas is merged with the first power generation oxidant gas and mixed, and the first power generation oxidant gas, the second power generation oxidant gas, Since the fuel cell module can be supplied with the temperature of the soak soaked, the second power generation oxidant gas having a low temperature is prevented from directly hitting the fuel cell by using the existing configuration. Is possible. As a result, it is also possible to suppress the occurrence of a temperature difference between the portions of the fuel battery cells, so that the fuel battery cells can be prevented from being damaged while the temperature of the fuel battery module is lowered.

  Further, if the communication part between the path for supplying the second power generation oxidant gas and the fuel cell module is provided separately from the communication part between the path for supplying the first power generation oxidant gas and the fuel cell module, Since the pressure of the supply path is low while the power generation oxidant gas is not supplied, there is a possibility that the atmosphere in the fuel cell module flows in the path for supplying the second power generation oxidant gas by flowing backward through the communicating portion. If the atmosphere in the fuel cell module flows backward through the supply path of the second power generating oxidant gas, the temperature in the fuel cell module may decrease, and the thermal efficiency may deteriorate. According to the present invention, the second power generation oxidant gas after bypassing is merged with the first power generation oxidant gas, and the supply path communicating with the fuel cell module is only the first power generation oxidant gas supply path. By doing so, it is possible to prevent the atmosphere in the fuel cell module from leaking and the temperature from decreasing.

  Also, by configuring in this way, the path for supplying the second power generation oxidant gas into the fuel cell module can also be used as the first power generation oxidant gas supply means, so that the apparatus is simply configured. can do.

By the way, when the solid oxide fuel cell device is started, an auto-thermal reforming reaction is performed in which a partial oxidation reforming reaction and a steam reforming reaction coexist. After the oxidant gas supply means for quality is provided, after the fuel cell module becomes hot and only the steam reforming reaction having higher reforming efficiency than the autothermal reforming reaction can be performed. Since no partial oxidation reforming reaction occurs, the reforming oxidant gas supply means becomes unnecessary.
Therefore, in the present invention, preferably, the reforming oxidant gas supply means is used as the second power generation oxidant gas supply means in the period of the steam reforming reaction in which the reforming oxidant gas supply means is unnecessary. It can also be used. By doing so, it is not necessary to separately provide a means for supplying the second power generating oxidant gas, and overheating can be suppressed with a simple configuration.

  In addition, by using a member different from the second power generation oxidant gas supply unit and the first power generation oxidant gas supply unit, the first power generation oxidant gas supply unit has the performance originally required for power generation. Therefore, the apparatus can be made inexpensive and compact.

  According to the solid oxide fuel cell of the present invention, it is possible to prevent an excessive temperature rise while improving the overall energy efficiency.

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. In one Embodiment of this invention, it is a flowchart which shows the procedure which performs forced cooling using the air for electric power generation and cooling.

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 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 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. 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 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 an air distribution chamber 72 on the downstream side. The air aggregation chamber 70 and the air distribution chamber 72 are connected by six air flow path pipes 74. Has been. Here, as shown in FIG. 3, the six air flow path pipes 74 form a set (74a, 74b, 74c, 74d, 74e, 74f), and the air in the air collecting chamber 70 corresponds to each set. It flows into the 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.
The air distribution chamber 72 is connected to an air introduction pipe 76 disposed in both side walls of the fuel cell module 2. The air introduction pipe 76 extends downward, and its lower end side communicates with the lower space of the power generation chamber 10. Then, the preheated air is introduced into the power generation chamber 10.

  The air distribution chamber 72 is connected to a bypass flow path 77 that branches from the reformed gas introduction pipe 62 and is connected by bypassing the air flow path pipe 74 that corresponds to the heat exchange region of the heat exchanger 22. . Further, although not shown, a flow path switching valve for switching the flow path is provided at a branch portion between the reformed gas introduction pipe 62 and the bypass flow path 77 so as to be switchable by the control unit 110.

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, a procedure for forced cooling of the fuel cell module will be described with reference to FIG.
First, in step S41 of FIG. 29, the detected temperature Td is read. Next, in step S42, the detected temperature Td read in step S41 is compared with the detected temperature Td before a predetermined time.
This comparison is for determining whether or not there is a risk of overheating that deviates from a preset appropriate temperature range in order to efficiently generate power.For example, overheating caused by deterioration, load Estimate overheating caused by follow-up operation. That is, step S42 operates as an excessive temperature rise estimation means.
When the difference between the detected temperature Td read in step S41 and the detected temperature Td before a predetermined time is equal to or lower than a predetermined threshold temperature, that is, when operating in the appropriate temperature range, one process of the flowchart of FIG. Ends.

  On the other hand, if the difference between the detected temperature Td and the detected temperature Td before the predetermined time exceeds the predetermined threshold temperature in step S42, that is, if an excessive temperature rise is estimated, the process proceeds to step S43.

  In step S43, the second air for power generation and cooling (second oxidant gas for power generation) is supplied into the fuel cell module 2 via the reforming air flow rate adjustment unit 42, so that the inside of the fuel cell module 2 The one-time process in the flowchart of FIG. 29 is completed.

  The second air that flows from the air supply source 40 via the reforming air flow rate adjustment unit 42 flows through the bypass passage 77, joins the empty space introduction 76, and reaches the fuel cell module 2. At that time, since there is no element that heats the second air between the air supply source 40 and the portion where it joins the empty space introduction 76, the second air is not heated after being taken in from the air supply source 40. Joins the empty space introduction 76.

  When the second air merges into the introduction of the air vessel 76 at a temperature close to the temperature of the air supply source 40, while the power generation air is taken from the air supply source 40 and is not determined to be overheated In the same manner as above, the air is heated by the air heat exchanger 22 for heating the power generation air. The temperature of the heated power generation air is lowered by mixing with the second air that is not heated. By supplying the power generation air whose temperature has been lowered into the fuel cell module 2, the temperature in the fuel cell module 2 can be lowered, and the overheated state can be eliminated.

  At this time, the cooling effect is increased by adjusting the flow rate ratio between the power generation air and the second air so that the power generation air is lowered, which is effective when the degree of excessive temperature rise becomes serious.

  In order to solve the above-described problems, the present invention uses a supplied fuel and oxidant gas to generate a power generation reaction in a fuel battery cell, and uses the fuel cell module for power generation. Fuel supply means for supplying fuel, first oxidant gas supply means for power generation for supplying first oxidant gas used for power generation from the oxidant gas supply source to the fuel cell module, and fuel supplied by the fuel supply means Among these, the combustion part that heats the fuel cell module by burning the remaining fuel that is not used for power generation, and the first oxidant gas supply means for power generation, the exhaust gas generated in the combustion part and the first In a solid oxide fuel cell device, comprising: a heat exchanging unit that exchanges heat with an oxidant gas for power generation; and a control unit that controls the fuel supply unit and the first oxidant gas supply unit for power generation. And a second power generation oxidant gas supply means for supplying a second power generation oxidant gas used for power generation from the oxidant gas supply source to the fuel cell module, and the control means includes an excessive temperature in the fuel cell module. An excessive temperature rise estimation means for estimating the occurrence of the rise, and when the occurrence of an excessive temperature rise is estimated by the excess temperature rise estimation means, the second power generating oxidant gas is caused to flow into the fuel cell module, thereby Forcibly cooling means for lowering the temperature in the battery module, and the second power generation oxidant gas supply means is configured such that the temperature of the second power generation oxidant gas is lower than that of the first power generation oxidant gas. The second power generation oxidant gas is configured to flow into the fuel cell module by bypassing at least a part of the heat exchange section.

  In the present invention configured as described above, the fuel supply means, the first power generation oxidant gas supply means, and the second power generation oxidant gas supply means are used to generate power using fuel cells. The fuel, the first power generation oxidant gas, and the second power generation oxidant gas are supplied to the battery module, respectively. The fuel cell module generates power using the supplied fuel, the first power generation oxidant gas and the second power generation oxidant gas, and the remaining fuel not used for power generation is burned in the combustion section, Is heated. Further, the exhaust gas generated by the combustion is used to raise the temperature of the power generation oxidant gas by heat exchange with the first power generation oxidant gas upstream of the fuel cell module. The control means controls the fuel supply means based on the demand power detected by the demand power detection means. When excessive temperature rise occurs, it is determined that there is a risk of overheating by the overheating temperature estimation means provided in the control means, and the second power generation oxidant gas having a temperature lower than that of the first power generation oxidant gas. Is forced to flow into the fuel cell module to activate the forced cooling means for lowering the temperature in the fuel cell module.

  According to the solid oxide fuel cell of the present invention, when the forced cooling means supplies the second power generation oxidant gas to the fuel cell module, the second power generation oxidant gas is supplied so as to bypass the heat exchange section. Thus, the temperature of the second power generation oxidant gas introduced from the same oxidant gas supply source as that of the first power generation oxidant gas is made lower than that of the first power generation oxidant gas. Since the temperature in the fuel cell module is lowered by allowing the second power generating oxidant gas to flow into the fuel cell module, the fuel cell can be increased by increasing the supply amount of the first power generating oxidant gas as in the conventional case. Compared to the case of cooling the inside of the module, an excessive temperature rise can be effectively avoided with a small flow rate. Therefore, the amount of the first power generation oxidant gas is increased, the pressure in the fuel cell module is increased, and it is possible to prevent fuel depletion caused by the fuel gas becoming difficult to enter the fuel cell module. Moreover, it is not necessary to install a blower having an excessive specification, which is preferable.

  As described above, the problem of excessive temperature rise can be solved by supplying the second power generation oxidant gas, but if the second power generation oxidant gas having a low temperature is directly applied to the fuel cell, The portion directly hit by the oxidant gas for second power generation is cooled too much as compared with the portion not directly hit, and the portion directly hit by the oxidant gas for second power generation and the portion not hit directly. There is a concern that a difference in thermal expansion occurs due to a temperature difference, and stress is applied to damage the fuel cell.

Therefore, in the present invention, it is preferable to have a temperature raising means for raising the temperature of the bypassed second power generation oxidant gas before supplying the second power generation oxidant gas to the fuel cell module.
According to the present invention configured as described above, it is possible to prevent the second power generating oxidant gas having a low temperature from directly hitting the fuel cell. As a result, it is also possible to suppress the occurrence of a temperature difference between the portions of the fuel battery cells, so that the fuel battery cells can be prevented from being damaged while the temperature of the fuel battery module is lowered.

Further, in the present invention, the temperature raising means mixes the bypassed second power generation oxidant gas and the first power generation oxidant gas before supplying the second power generation oxidant gas to the fuel cell module. It is preferable to provide a part.
According to the present invention thus configured, the second power generation oxidant gas is merged with the first power generation oxidant gas and mixed, and the first power generation oxidant gas, the second power generation oxidant gas, Since the fuel cell module can be supplied with the temperature of the soak soaked, the second power generation oxidant gas having a low temperature is prevented from directly hitting the fuel cell by using the existing configuration. Is possible. As a result, it is also possible to suppress the occurrence of a temperature difference between the portions of the fuel battery cells, so that the fuel battery cells can be prevented from being damaged while the temperature of the fuel battery module is lowered.

  Further, if the communication part between the path for supplying the second power generation oxidant gas and the fuel cell module is provided separately from the communication part between the path for supplying the first power generation oxidant gas and the fuel cell module, Since the pressure of the supply path is low while the power generation oxidant gas is not supplied, there is a possibility that the atmosphere in the fuel cell module flows in the path for supplying the second power generation oxidant gas by flowing backward through the communicating portion. If the atmosphere in the fuel cell module flows backward through the supply path of the second power generating oxidant gas, the temperature in the fuel cell module may decrease, and the thermal efficiency may deteriorate. According to the present invention, the second power generation oxidant gas after bypassing is merged with the first power generation oxidant gas, and the supply path communicating with the fuel cell module is only the first power generation oxidant gas supply path. By doing so, it is possible to prevent the atmosphere in the fuel cell module from leaking and the temperature from decreasing.

  Also, by configuring in this way, the path for supplying the second power generation oxidant gas into the fuel cell module can also be used as the first power generation oxidant gas supply means, so that the apparatus is simply configured. can do.

By the way, when the solid oxide fuel cell device is started, an auto-thermal reforming reaction is performed in which a partial oxidation reforming reaction and a steam reforming reaction coexist. After the oxidant gas supply means for quality is provided, after the fuel cell module becomes hot and only the steam reforming reaction having higher reforming efficiency than the autothermal reforming reaction can be performed. Since no partial oxidation reforming reaction occurs, the reforming oxidant gas supply means becomes unnecessary.
Therefore, in the present invention, preferably, the reforming oxidant gas supply means is used as the second power generation oxidant gas supply means in the period of the steam reforming reaction in which the reforming oxidant gas supply means is unnecessary. It can also be used. By doing so, it is not necessary to separately provide a means for supplying the second power generating oxidant gas, and overheating can be suppressed with a simple configuration.

  In addition, by using a member different from the second power generation oxidant gas supply unit and the first power generation oxidant gas supply unit, the first power generation oxidant gas supply unit has the performance originally required for power generation. Therefore, the apparatus can be made inexpensive and compact.

  As mentioned above, although preferable embodiment of this invention was described, a various change can be added to embodiment mentioned above. For example, in the above-described embodiment, all the air flow path pipes 74 of the air heat exchanger 22 are bypassed and merged in the air distribution chamber 72. However, the position of the merged portion of the power generation air and the second air Can be designed in various ways depending on how much the temperature of the second air at the time of merging needs to be adjusted. After partially bypassing the air flow path pipe 74 which is the main heating part of the air heat exchanger 22 and joining in the middle of the heating part or flowing into the air heat exchanger 22, the air in the air heat exchanger 22 By bypassing from the middle of the flow path pipe 74 and joining downstream of the air heat exchanger 22, for example, the second air can be heated to a temperature that does not break even when directly sprayed onto the fuel cell. Further, as in the above-described embodiment, if all the air flow path pipes 74 of the air heat exchanger 22 are bypassed and merged with the air distribution chamber 72 or the air introduction pipe 76 disposed downstream thereof, The cooling effect can be enhanced. For example, if a confluence portion is provided immediately before the supply to the fuel cell module 2 near the downstream end of the empty vessel introduction pipe 76, the cooling effect can be exerted to the maximum. The range is maximized.

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 apparatus 52 Control box 54 Inverter 77 Bypass flow path 83 Ignition apparatus 84 Fuel cell 110 Control part (control means)
112 operation device 114 display device 116 alarm device 126 power state detection sensor (demand power detection means)
132 Fuel flow sensor (fuel supply detection sensor)
138 Pressure sensor (reformer pressure sensor)
140 Exhaust temperature sensor (temperature detection means)
142 Power generation chamber temperature sensor (temperature detection means)
148 Reformer temperature sensor (temperature detection means)
150 Outside temperature sensor

Claims (4)

A fuel cell module for generating electricity by generating a power generation reaction in the fuel cell using the supplied fuel and oxidant gas; and
Fuel supply means for supplying fuel used for power generation to the fuel cell module;
First oxidant gas supply means for power generation for supplying a first oxidant gas used for power generation from the oxidant gas supply source to the fuel cell module;
Of the fuel supplied by the fuel supply means, a combustion unit that heats the fuel cell module by burning the remaining fuel that is not used for power generation; and
A heat exchanging unit provided in the first power generating oxidant gas supply means for exchanging heat between the exhaust gas generated in the combustion unit and the first power generating oxidant gas;
A solid oxide fuel cell device comprising: the fuel supply means; and a control means for controlling the first power generation oxidant gas supply means.
A second power generation oxidant gas supply means for supplying a second power generation oxidant gas used for power generation from the oxidant gas supply source to the fuel cell module;
The control means includes an excessive temperature rise estimation means for estimating the occurrence of an excessive temperature rise in the fuel cell module;
When an excessive temperature rise is estimated by the excessive temperature rise estimation means, the second power generating oxidant gas is caused to flow into the fuel cell module to forcibly reduce the temperature in the fuel cell module. Cooling means,
The second power generation oxidant gas supply means is configured to convert the second power generation oxidant gas into the heat exchange unit so that the temperature of the second power generation oxidant gas is lower than that of the first power generation oxidant gas. A solid oxide fuel cell device configured to bypass at least a portion of the fuel cell module and flow into the fuel cell module.   2. The temperature raising means for raising the temperature of the bypassed second power generating oxidant gas before supplying the second power generating oxidant gas to the fuel cell module, according to claim 1, Solid oxide fuel cell.   The temperature raising means mixes the bypassed second power generating oxidant gas with the first power generating oxidant gas before supplying the second power generating oxidant gas to the fuel cell module. The solid oxide fuel cell according to claim 2, further comprising a portion. A reforming section for reforming the fuel by a partial oxidation reforming reaction and / or a steam reforming reaction;
Reforming air supply means for supplying reforming air to the reformer;
A reforming water supply means for supplying water for steam reforming reaction to the reformer,
The control unit performs an autothermal reforming reaction in which a partial oxidation reforming reaction and a steam reforming reaction coexist in the reformer at the time of start-up to raise the temperature in the fuel cell module, Control to stop the partial oxidation reforming reaction and perform only the steam reforming reaction after reaching the temperature of
4. The fuel cell module according to claim 3, wherein the second power generation oxidant gas is supplied to the fuel cell module using the reforming air supply unit after reaching the predetermined temperature. 5. Solid oxide fuel cell device.

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