JP5412975B2 - Solid oxide fuel cell - Google Patents

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 fuel gas and air.

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

  In this SOFC, water vapor and / 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 transmitted to fuel, SOFC, oxidant, etc., and used to increase their temperature.

Conventional SOFCs are generally operated with power generation output kept constant. However, SOFCs can be used for facilities where there is almost no electricity demand at night or where there is a significant change in electricity demand during the day and night. When installing, it is necessary to change the power generation output value according to the required power generation amount.
For example, in the conventional SOFC described in Patent Document 1, two types of operating temperatures of the power generation unit are set depending on the amount of power usage, and the operation of the power generation unit is performed in a time zone where the power usage is low. By setting the temperature low, the amount of fuel gas used to maintain the operating temperature of the power generation unit is reduced, reducing costs and reducing CO ₂ emissions.

  In such a conventional SOFC, since city gas and kerosene used as fuel gas contain sulfur, the sulfur contained in the fuel gas adheres to the fuel battery cell, and the activity of the fuel battery cell ( There is a problem that the power generation capacity) decreases.

JP 2005-216618 A

Further, in the conventional SOFC, a fuel gas before reforming is provided by providing a desulfurizer that removes sulfur contained in the fuel gas upstream of the reformer that reforms the fuel gas and supplies the fuel cell. What removes sulfur from the is also known as a well-known technique.
However, in such a desulfurizer, it is difficult to desulfurize even a very small amount of sulfur in the fuel gas. Therefore, as the power generation operation is performed for a long period of time, these small amounts of sulfur that cannot be completely desulfurized gradually become fuel cells. There is a problem in that the activity (power generation capacity) of the fuel battery cell is remarkably reduced as compared with the beginning of the power generation operation.

  Accordingly, the present invention has been made to solve the above-described problems of the prior art, and removes sulfur adhering to the fuel cell based on predetermined conditions during the power generation operation by the fuel cell module. An object of the present invention is to provide a solid oxide fuel cell capable of preventing the inactivation of the fuel cell by performing the operation (hereinafter referred to as “cleaning mode operation”).

In order to achieve the above object, the present invention provides a solid oxide fuel cell that generates electricity by reacting fuel gas and air, and is disposed in a power generation chamber in a fuel cell module, and a plurality of solid electrolyte fuels A fuel cell assembly including battery cells, a desulfurizer that removes sulfur contained in the fuel gas, a reformer that reforms the fuel gas and supplies it to the fuel cell assembly, and the reformer A fuel gas supply means for supplying fuel gas to the fuel cell assembly, a power generation air supply means for supplying power generation air to the fuel cell assembly, and a fuel cell from the power generation air supply means when a predetermined condition is reached. Controlling the power generation air supply means so as to reduce the amount of power generation air supplied to the cell assembly and / or the amount of fuel gas supplied from the fuel gas supply means to the fuel cell assembly. I will increase the amount And controls the fuel gas supply means, by forcibly increasing the temperature of the generating chamber to a temperature above 950 ° C., was attached to the fuel cell assembly without being completely desulfurized by the desulfurizer sulfur And a control unit that executes a cleaning mode operation for removing water.
In the present invention configured as described above, when a predetermined condition is reached, the control unit reduces the amount of power generation air supplied from the power generation air supply means to the fuel cell assembly. The temperature of the power generation chamber is set to 950 ° C. by controlling the air supply means and / or controlling the fuel gas supply means so as to increase the amount of fuel gas supplied from the fuel gas supply means to the fuel cell assembly. Since the cleaning mode operation is executed by forcibly raising the temperature, it is possible to remove sulfur adhering to the fuel cell assembly without being desulfurized by the desulfurizer. Inactivation can be prevented.

In the present invention, it is preferable that the predetermined condition for the control unit to execute the cleaning mode operation is when a predetermined power generation operation time has elapsed.
In the present invention configured as described above, since the control unit performs the cleaning mode operation when a predetermined power generation operation time has elapsed, the sulfur adhering to the fuel cell assembly without being completely desulfurized by the desulfurizer. And the inactivation of the fuel battery cell due to the adhesion of sulfur can be prevented. Since a predetermined condition for executing the cleaning mode operation is a condition that a predetermined power generation operation time elapses, it is not necessary to carry out the cleaning mode operation unnecessarily, and smooth steady power generation can be maintained. At the same time, it is possible to cope with the malfunction of the fuel battery cell due to the adhesion of sulfur.

In the present invention, preferably, the predetermined condition for the control unit to execute the cleaning mode operation may be when the voltage of the fuel cell reaches a predetermined voltage.
In the present invention configured as described above, the control unit performs the cleaning mode operation when the voltage of the fuel cell reaches a predetermined voltage, so that the control unit adheres to the fuel cell assembly without being completely desulfurized by the desulfurizer. Sulfur contained can be removed, and inactivation of the fuel battery cell due to the adhesion of sulfur can be prevented. Since the cleaning operation is performed while checking the voltage of the fuel cell itself, cleaning can be performed at an appropriate timing even when more than expected sulfur is attached to the fuel cell due to some problem.

In the present invention, it is preferable that the control unit performs the cleaning mode operation by raising the temperature of the power generation chamber to a temperature higher than a temperature range in which steady power generation operation by the fuel cell module is possible.
In the present invention configured as described above, when the cleaning mode operation is executed by the control unit, the temperature of the power generation chamber rises to a temperature higher than the temperature range in which the steady power generation operation by the fuel cell module is possible. Therefore, the removal amount of sulfur adhering to the fuel cell assembly is increased, and inactivation of the fuel cell due to the adhesion of sulfur can be effectively prevented.

In the present invention, preferably, the control unit is performing low-load power generation operation at a temperature lower than a predetermined temperature within a temperature range in which the temperature of the power generation chamber is capable of steady power generation operation by the fuel cell module. In this case, the cleaning mode operation is executed by increasing the temperature of the power generation chamber to a temperature equal to or higher than the predetermined temperature within a temperature range where the steady power generation operation is possible.
In the present invention configured as described above, when the low-load power generation operation is performed at a temperature lower than a predetermined temperature within a temperature range in which the temperature of the power generation chamber is capable of steady power generation operation by the fuel cell module. In order to perform the cleaning mode operation by raising the temperature of the power generation chamber to a temperature equal to or higher than a predetermined temperature within the temperature range where the steady power generation operation is possible, the steady power generation operation is performed even during the cleaning mode operation. This makes it possible to remove sulfur adhering to the fuel cell. In addition, because the temperature of the power generation chamber is raised within the temperature range where steady power generation operation is possible and the cleaning mode operation is executed, the burden on the fuel cell due to heating due to the temperature increase of the power generation chamber is minimized. Can be suppressed.

In the present invention, it is preferable that the control unit changes the predetermined power generation operation time for executing the cleaning mode operation based on a history of operation by the fuel cell module.
In the present invention configured as described above, the amount of sulfur actually attached to the fuel cell varies depending on the operation history of the fuel cell module, but the predetermined power generation operation which is a condition for executing the cleaning mode operation Since the time is changed based on the operation history of the fuel cell module, the time interval between the cleaning mode operations according to the actual sulfur adhesion amount can be set appropriately. Moreover, the burden on the fuel battery cell due to heating accompanying the temperature rise of the power generation chamber can be minimized.

In the present invention, preferably, the control unit performs the predetermined power generation operation time for executing the cleaning mode operation within a temperature range in which the temperature of the power generation chamber is within a temperature range in which the fuel cell module can perform a steady power generation operation. The time is changed to a shorter time as the ratio of the low load power generation operation performed when the temperature is lower than the predetermined temperature in the operation history by the fuel cell module is higher.
In the present invention configured as described above, the higher the ratio of the low load power generation operation in the operation history of the fuel cell module, the shorter the time during which the fuel cell assembly is exposed to a high temperature. Although the amount of sulfur adhesion in the cell also increases, the predetermined time until the next cleaning mode operation is executed after the execution of the cleaning mode operation is changed to a short time, and the execution of the next cleaning mode operation is accelerated. Thus, it is possible to perform an appropriate operation according to the amount of sulfur attached to the actual fuel cell.

In the present invention, preferably, the control unit executes the cleaning mode operation for a predetermined duration, and when the voltage of the fuel cell reaches a predetermined voltage during the execution of the cleaning mode operation, Even within the duration, the cleaning mode operation is forcibly terminated.
In the present invention configured as described above, if the voltage of the fuel cell module reaches a predetermined voltage even if the cleaning mode operation is continued, the cleaning mode operation is forcibly performed even within the predetermined duration. Since it is made to complete | finish, it can prevent exposing a fuel cell to high temperature uselessly, and can prevent deterioration of a fuel cell.

In the present invention, it is preferable that the control unit sets the predetermined power generation operation time, which is a condition for executing the cleaning mode operation, to be shorter as the aging time during which the power generation operation is performed by the fuel cell module is longer. Set to.
In the present invention configured as described above, in consideration of the fact that sulfur easily adheres to the fuel cell as the aging time of the fuel cell of the fuel cell module elapses, the predetermined power generation operation time is generated by the fuel cell module. By setting the time to be shorter as the aging time during which the operation is performed is shortened, it is possible to perform an appropriate operation according to the amount of sulfur deposition on the actual fuel cell by accelerating the execution of the cleaning mode operation. .

In the present invention, it is preferable that the predetermined condition for the control unit to execute the cleaning mode operation is a manual operation, and the control unit forcibly executes the cleaning mode operation by the manual operation.
In the present invention configured as described above, even if a failure occurs in the desulfurization process of the fuel gas, such as failure of the desulfurizer, the cleaning mode operation is forcibly executed by manual operation. Therefore, sulfur adhering to the fuel battery cell can be surely removed.

  According to the fuel cell of the present invention, during the power generation operation by the fuel cell module, the fuel cell is inactivated by performing a cleaning mode operation for removing sulfur adhering to the fuel cell based on a predetermined condition. Can be prevented.

1 is an overall configuration diagram showing a solid oxide fuel cell (SOFC) according to an embodiment of the present invention. 1 is a block diagram illustrating a solid oxide fuel cell (SOFC) according to an embodiment of the present invention. It is a time chart which shows the operation | movement at the time of starting of the solid oxide fuel cell (SOFC) by one Embodiment of this invention. It is a time chart which shows the operation | movement at the time of operation stop of the solid oxide fuel cell (SOFC) by one Embodiment of this invention. It is a time chart which shows the operation | movement at the time of the cleaning mode driving | operation of the 1st example of the solid oxide fuel cell (SOFC) by one Embodiment of this invention. It is a time chart which shows the comparative example of FIG. It is a time chart which shows the operation | movement at the time of the cleaning mode driving | operation of the 2nd example of the solid oxide fuel cell (SOFC) by one Embodiment of this invention. It is a time chart which shows the operation | movement at the time of the cleaning mode driving | operation of the 3rd example of the solid oxide fuel cell (SOFC) by one Embodiment of this invention. It is a time chart which shows the operation | movement at the time of the cleaning mode driving | operation of the 4th example of the solid oxide fuel cell (SOFC) by one Embodiment of this invention. It is a time chart which shows the operation | movement at the time of the cleaning mode driving | operation of the 5th example of the solid oxide fuel cell (SOFC) by one Embodiment of this invention.

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

The fuel cell module 2 includes a housing 6, and a sealed space 8 is formed inside the housing 6 via a heat insulating material (not shown, but the heat insulating material is not an essential component and may not be necessary). Is formed. In addition, you may make it not provide a heat insulating material. A fuel cell assembly 12 that performs a power generation reaction with fuel gas and an oxidant (air) is disposed in a power generation chamber 10 that is a lower portion of the sealed space 8. The fuel cell assembly 12 includes a plurality of fuel cell stacks 14, and the fuel cell stack 14 includes a plurality of fuel cell units 16. Thus, the fuel cell assembly 12 has a plurality of fuel cell units 16, and all of these fuel cell units 16 are connected in series.
Each fuel cell unit 16 is a bottomed cylindrical member made of a ceramic material, and forms a multilayer structure of an air electrode, a solid oxide electrolyte, and a fuel electrode from the inside to the outside. .
Further, when the air contacts the inner wall (air electrode) of the fuel cell unit 16 and the fuel gas contacts the outer wall (fuel electrode) of the fuel cell unit 16, O ²⁻ ions are ^generated in the fuel cell unit 16. It moves, and an electrochemical reaction takes place, and a potential difference is generated between the air electrode and the fuel electrode, so that power generation is performed.

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.
In the combustion chamber 18, a power generation air header 19 that supplies power generation air to the air electrode of each fuel cell unit 16 of the fuel cell assembly 12 is disposed.

Next, 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. doing.
Further, a preheater 21 for preheating the fuel gas and the reforming air before being supplied to the reformer 20 is disposed above the reformer 20.
Further, an evaporator 22 is disposed above the preheater 21, and water necessary for reforming in the reformer 20 is vaporized and supplied to the reformer 20 by the evaporator 22. Yes.

  In addition, a fuel gas dispersion chamber 23 is disposed below the power generation chamber 10, and the fuel gas reformed by the reformer 20 is uniformly dispersed in the fuel gas dispersion chamber 23, and is formed in the fuel cell assembly 12. It comes to be supplied.

Next, the auxiliary unit 4 evaporates by adjusting the flow rate of the water supplied from the pure water tank 26 that stores the water from the water supply source 24 such as a water supply and uses the filter to obtain pure water. A water flow rate adjusting unit 28 (such as a “water pump” driven by a motor) for supplying water at a predetermined flow rate to the vessel 23 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). The air adjusted to a predetermined flow rate by the power generation air flow rate adjustment unit 45 is supplied to the power generation air header 19 in the fuel cell module 2.

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, 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. 2 is a block diagram illustrating a solid oxide fuel cell (SOFC) according to an embodiment of the present invention.
As shown in FIG. 2, the solid oxide fuel cell 1 includes a control unit 60. The control unit 60 includes an operation button such as “ON” or “OFF” for operation by the user. A device 62, a display device 64 for displaying various data such as a power generation output value (wattage), and a notification device 66 for issuing a warning (warning) in an abnormal state are connected. In addition, this alerting | reporting apparatus 66 may be connected to the management center in a remote place, and may notify this management center of an abnormal state.

Next, signals from various sensors described below are input to the control unit 60.
First, the combustible gas detection sensor 70 is for detecting a gas leak, and is attached to the fuel cell module 2 and the auxiliary unit 4.
In the CO detection sensor 72, CO in the exhaust gas that is originally discharged to the outside through an exhaust gas passage (not shown) or the like leaks to an external housing (not shown) that covers the fuel cell module 2 and the accessory unit 4. This is to detect whether or not
The hot water storage state detection sensor 74 is for detecting the temperature and amount of hot water in a water heater (not shown).

The power state detection sensor 76 is for detecting the current and voltage of the inverter 54 and the distribution board (not shown). In addition, the power state detection sensor 76 can specifically detect the power (or current and voltage) generated in the fuel cell assembly 12 in the inverter 54.
The power generation air flow rate detection sensor 78 is for detecting the flow rate of the power generation air supplied to the power generation chamber 10.
The reforming air flow rate sensor 80 is for detecting the flow rate of the reforming air supplied to the reformer 20.
The fuel flow sensor 82 is for detecting the flow rate of the fuel gas supplied to the reformer 20.

The water flow rate sensor 84 is for detecting the flow rate of pure water (steam) supplied to the reformer 20.
The water level sensor 86 is for detecting the water level of the pure water tank 26.
The pressure sensor 88 is for detecting the pressure on the upstream side outside the reformer 20.
The exhaust temperature sensor 90 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 92 is provided on the front side and the rear side in the vicinity of the fuel cell assembly 12, and the temperature in the vicinity of the fuel cell stack 14 in the power generation chamber 10 (hereinafter referred to as “power generation”). The temperature of the fuel cell stack 14 (that is, the fuel cell unit 16 itself) is estimated by detecting the room temperature ").
The combustion chamber temperature sensor 94 is for detecting the temperature of the combustion chamber 18.
The exhaust gas chamber temperature sensor 96 is for detecting the temperature of the exhaust gas in the exhaust gas chamber 78.
The reformer temperature sensor 98 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 100 is for detecting the temperature of 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 60, and the control unit 60, based on data from these signals, the water flow rate adjustment unit 28, the fuel flow rate adjustment unit 38, the reforming air flow rate adjustment unit 44, A control signal is sent to the power generation air flow rate adjusting unit 45 to control each flow rate in these units.
Further, the control unit 60 sends a control signal to the inverter 54 to control the power supply amount.

Next, the operation at the time of starting by the solid oxide fuel cell (SOFC) according to the present embodiment will be described with reference to FIG. FIG. 3 is a time chart showing the operation at the time of 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 via the preheater 21 of the fuel cell module 2. At the same time, power generation air is supplied from the power generation air flow rate adjustment unit 45 to the power generation air header 19 of the fuel cell module 2.
Immediately after this, fuel gas is also supplied from the fuel flow rate adjusting unit 38, and the fuel gas mixed with the reforming air via the preheater 21 passes through the reformer 20 and the fuel gas dispersion chamber 23. It is supplied into the power generation chamber 10, passes through the fuel cell stack 14 and the fuel cell unit 16, and reaches the combustion chamber 18. Further, in the power generation chamber 10, the fuel gas introduced from the fuel gas dispersion chamber 23 comes into contact with the fuel electrode of each fuel cell unit 16, so that the air in each fuel cell unit 16 is generated from the power generation air header 19. Electricity is generated by an electrochemical reaction with the air for power generation supplied to the electrode.

Next, ignition is performed by an ignition device (not shown), and the fuel gas and air (reforming air and generating air) in the combustion chamber 18 are combusted. Exhaust gas is generated by the combustion of the fuel gas and air, and the exhaust gas warms the fuel gas containing the reforming air in the reformer 20 and is supplied to the hot water production apparatus 50.
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 from the fuel gas dispersion chamber 23 to the lower side of the fuel cell stack 14, 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 98 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.

  Thus, after the fuel cell module 2 is ignited by an ignition device (not shown), the partial oxidation reforming reaction POX, the autothermal reforming reaction ATR, and the steam reforming reaction SR proceed sequentially, The temperature in the power generation chamber 10 gradually increases. Next, when the temperature in the power generation chamber 10 and the fuel cell unit 16 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 module 16 is closed. Electricity generation by the battery module 2 is started, whereby current flows through the circuit. Due to the power generation of the fuel cell module 2, the fuel cell unit 16 itself also generates heat, and the temperature of the fuel cell unit 16 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, fuel gas and air larger than the amount of fuel gas and air consumed by the fuel cell unit 16 are supplied, and combustion in the combustion chamber 18 is continued. During power generation, power generation proceeds in a steam reforming reaction SR with high reforming efficiency.

Next, the operation when the solid oxide fuel cell (SOFC) according to the present embodiment is stopped will be described with reference to FIG. FIG. 4 is a time chart showing the operation when the solid oxide fuel cell (SOFC) is stopped according to this embodiment.
As shown in FIG. 4, when the operation of the fuel cell module 2 is stopped, first, the fuel flow rate adjustment unit 38 and the water flow rate adjustment unit 28 are operated to supply fuel gas and water vapor to the reformer 20. Reduce the amount.

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

Next, the operation during the cleaning mode operation of the first example of the solid oxide fuel cell (SOFC) according to the present embodiment will be described with reference to FIGS.
FIG. 5 is a time chart showing the operation during the cleaning mode operation of the first example of the solid oxide fuel cell (SOFC) according to the present embodiment, and FIG. 6 is a time chart showing a comparative example of FIG.

First, in FIG. 5, the vertical axis represents the power generation chamber temperature (T) and the cell voltage (V) (the voltage of the fuel cell assembly 12), and the horizontal axis represents time (t).
The cleaning mode operation of the first example by the solid oxide fuel cell (SOFC) 1 of the present embodiment is a temperature region in which the power generation chamber temperature (T) is 850 ° C. or more and 950 ° C. or less (hereinafter referred to as “steady power generation operation temperature region”). And when the cell voltage (V) is larger than the lower limit voltage value V0 (= 0.76V) and the steady power generation operation is performed, it is executed under predetermined conditions. ing.

More specifically, first, after the start-up operation of the fuel cell module 2 described with reference to FIG. 3, the power generation operation is started at time t0.
Next, the power generation operation time τ1 (= 5000 hours) from the start of the power generation operation at time t0 to the start of the cleaning mode operation at time t1 and the lower limit voltage value V0 (= 0.76V) of the cell voltage (V). Is determined in advance as a reference value for determining whether or not to start the cleaning mode operation.
For example, as shown in FIG. 5, when the cell voltage (V) does not reach the lower limit voltage value V0 from time t0 to time t1 when the power generation operation time τ1 has elapsed, at time t1, the control unit 60 performs the fuel gas operation. A signal is sent to each of the fuel flow rate adjustment unit 38 that is a supply means and the power generation air flow rate adjustment unit 45 that is a power generation air supply means, and the first cleaning mode operation is started regardless of the power generation amount by the power generation operation so far. Is done.
On the other hand, when the cell voltage (V) detected by the power state detection sensor 76 reaches the lower limit voltage value V0 by the time t1 when the power generation operation time τ1 has elapsed from the time t0, the power generation operation time from the time t0 at that time. Without waiting for the elapse of τ1, the first cleaning mode operation is forcibly started regardless of the amount of power generated by the previous power generation operation.

  When the first cleaning mode operation is started at time t1, the control unit 60 sends a signal to each of the fuel flow rate adjustment unit 38 as the fuel gas supply unit and the power generation air flow rate adjustment unit 45 as the power generation air supply unit. send. Based on these signals from the control unit 60, the power generation chamber temperature (T) is compulsory to a predetermined temperature (950 ° C. to 1000 ° C.) higher than the steady power generation operation temperature range, regardless of the amount of power generated by the power generation operation so far. The fuel gas supplied from the fuel flow rate adjustment unit 38 to the reformer 20 is increased in comparison with the steady power generation operation performed from time t0 to time t1 and The power generation air supplied from the air flow rate adjustment unit 45 to the power generation air header 19 is reduced as compared with the steady power generation operation.

That is, in the cleaning mode operation, by increasing the fuel gas supplied from the fuel flow rate adjusting unit 38 to the reformer 20, the fuel gas supplied to the combustion chamber 18 is increased to increase the combustion amount. The temperature of the combustion chamber 18 rises, and the temperature of the reformer 20 disposed above the combustion chamber 18 also rises. As a result, high-temperature fuel gas is also introduced from the fuel gas dispersion chamber 23 into the power generation chamber 10 to increase the temperature of the power generation chamber 10 and increase the temperature of the fuel cell assembly 12 to increase the temperature. . At the same time, the power generation air supplied from the power generation air flow rate adjusting unit 45 to the power generation air header 19 is reduced, thereby generating power supplied from the power generation air header 19 to the air electrode of each fuel cell unit 16. And the cooling effect on each fuel cell unit 16 by the power generation air is reduced, so that the temperature of the fuel cell assembly 12 can be kept high.
As a result of increasing the temperature of the fuel cell assembly 12 in the cleaning mode operation, sulfur adhering to each fuel cell unit 16 is removed.

Next, the time (t2-t1) during which the first cleaning mode operation is started at time t1 and the cleaning mode operation is continued until the first cleaning mode operation is completed at time t2 is 2 hours or more and 3 hours or less. The predetermined time is set in advance.
Further, as shown in FIG. 5, the cell voltage at the time when the initial cleaning mode is completed at time t2 is higher than the cell voltage at time t1 because sulfur adhering to each fuel cell unit 16 is removed. The voltage has recovered.
Furthermore, from time t2 to time t3, the steady power generation operation in which the power generation chamber temperature is within the steady power generation operation temperature region is executed again.

  Here, in the n-th (n ≧ 2) cleaning mode operation, does the power generation operation time τn from the time when the previous cleaning mode operation ends to the time when the next cleaning mode operation starts reaches 5000 hours? Or, if the cell voltage reaches one of the conditions where the cell voltage reaches the lower limit voltage value V0 before the power generation operation time τn reaches 5000 hours, regardless of the power generation amount by the power generation operation so far The cleaning mode operation is set in advance so as to be executed immediately.

For example, at time t3 shown in FIG. 5, the cell voltage has not reached the lower limit voltage value V0, but since the power generation operation time τ2 after the completion of the first cleaning mode operation at time t2 has reached 5000 hours, Regardless of the amount of power generated by the power generation operation, the second cleaning mode operation is executed, and, similar to the first cleaning mode operation, the power generation chamber temperature (T) is a predetermined temperature (950 ° C.- The temperature is forcibly increased to 1000 ° C., the second cleaning mode operation is terminated at time t4, and the steady power generation operation in which the power generation chamber temperature is within the steady power generation operation temperature region is executed again.
Note that the operation continuation time (t4-t3) from the start to the end of the second cleaning mode operation is also set in advance to a predetermined time of 2 hours or more and 3 hours or less, as in the first cleaning mode operation. ing.

Further, at time t5 shown in FIG. 5, since the power generation operation time τ3 after the end of the second cleaning mode operation at time t4 reaches 5000 hours, the cell voltage has reached the lower limit voltage value V0. Regardless of the amount of power generated by the power generation operation up to, the third cleaning mode operation is executed, and the power generation chamber temperature (T) is higher than the steady power generation operation temperature region as in the first and second cleaning mode operations. The temperature is forcibly increased to (950 ° C. to 1000 ° C.), the third cleaning mode operation is terminated at time t6, and the steady power generation operation in which the power generation chamber temperature is within the steady power generation operation temperature region is executed again.
Note that the operation continuation time (t6-t5) from the start to the end of the third cleaning mode operation is also set to a predetermined time of 2 hours or more and 3 hours or less as in the first and second cleaning mode operations. It is set in advance.

Similarly, at the time t7 shown in FIG. 5, the cell voltage has reached the lower limit voltage value V0 before the power generation operation time τ4 reaches 5000 hours after the third cleaning mode operation ends at the time t6. Regardless of the amount of power generated by the previous power generation operation, the fourth cleaning mode operation is executed, and the power generation chamber temperature (T) is higher than the steady power generation operation temperature region in the same manner as the third cleaning mode operation. The temperature is forcibly increased to (950 ° C. to 1000 ° C.), the fourth cleaning mode operation is terminated at time t8, and the steady power generation operation in which the power generation chamber temperature is within the steady power generation operation temperature region is executed again.
Note that the operation continuation time (t8-t7) from the start to the end of the third cleaning mode operation is also set to a predetermined time of 2 hours or more and 3 hours or less, as in the first and second cleaning mode operations. It is set in advance.

On the other hand, FIG. 6 is a time chart when the cleaning mode operation is not executed at all as a comparative example of FIG.
As shown in FIG. 6, when the cleaning mode operation is not executed at time t1 when the power generation operation time τ1 has elapsed from time t0, the cell voltage (V) continues to decrease after time t1. Further, if the cleaning mode operation is not executed even when the cell voltage (V) reaches the lower limit voltage value V0 at time t9, the cell voltage (V) continues to decrease with a relatively large slope after time t9.

  According to the cleaning mode operation of the first example according to the present embodiment described above, regardless of the power generation amount by the fuel cell module 2, the power generation operation time after the start operation is ended and the power generation operation is started, and the previous time When the power generation operation time after the completion of the cleaning mode operation and restarting the power generation operation reaches a predetermined time (for example, 5000 hours) or the cell voltage during the power generation operation reaches a predetermined lower limit voltage value, the control is performed. The cleaning mode operation is performed by the unit 60, and the temperature of the power generation chamber 10 is forcibly increased to a predetermined temperature (950 ° C. to 1000 ° C.) higher than that in the steady power generation operation temperature region and attached to the fuel cell assembly 12. Since the sulfur which is carrying out can be removed effectively, the inactivation of the fuel cell by sulfur adhesion can be prevented.

Next, the operation during the cleaning mode operation of the second example of 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 during the cleaning mode operation of the second example of the solid oxide fuel cell (SOFC) according to the present embodiment.

  As shown in FIG. 7, the cleaning mode operation of the second example by the solid oxide fuel cell (SOFC) 1 of this embodiment is a steady power generation operation temperature region in which the power generation chamber temperature (T) is 850 ° C. or more and 950 ° C. or less. Predetermined conditions when the low load power generation operation is performed at a temperature lower than the predetermined temperature (less than 900 ° C.) and the cell voltage (V) is larger than the lower limit voltage value V0 (= 0.74V). It is supposed to be executed below.

More specifically, first, after the start-up operation of the fuel cell module 2 described with reference to FIG. 3, the power generation operation time τ1 from the start of the low load power generation operation at time t100 to the start of the cleaning mode operation at time t101. (= 5000 hours) and the lower limit voltage value V0 (= 0.74V) of the cell voltage (V) are set in advance as reference values for determining whether or not to start the cleaning mode operation.
For example, as shown in FIG. 7, when the cell voltage (V) does not reach the lower limit voltage value V0 from time t100 to time t101 when the power generation operation time τ1 has elapsed, at time t101, the control unit 60 performs the fuel gas operation. A signal is sent to each of the fuel flow rate adjustment unit 38 that is a supply means and the power generation air flow rate adjustment unit 45 that is a power generation air supply means, and the first cleaning mode operation is started regardless of the power generation amount by the power generation operation so far. Is done.
On the other hand, when the cell voltage (V) detected by the power state detection sensor 76 reaches the lower limit voltage value V0 from time t100 to time t101 when the power generation operation time τ1 has elapsed, the power generation operation time from time t100 to that time. The first cleaning mode operation is forcibly started without waiting for the elapse of τ1, and after the predetermined time (2 to 3 hours) operation, the first cleaning mode operation is terminated at time t102, and the low load power generation operation is executed again. The

  Further, when the first cleaning mode operation is started at time t101, the control unit 60 sends a signal to each of the fuel flow rate adjustment unit 38 as the fuel gas supply unit and the power generation air flow rate adjustment unit 45 as the power generation air supply unit. send. Based on these signals from the control unit 60, a low-load power generation operation in which the power generation chamber temperature (T) is within the steady power generation operation temperature region (850 ° C. to 950 ° C.) is performed regardless of the power generation amount by the power generation operation so far. The fuel gas supplied from the fuel flow rate adjustment unit 38 to the reformer 20 is supplied by the time t100 to t101 so that the temperature is forcibly increased to a predetermined temperature (for example, 950 ° C.) higher than the temperature of the power generation chamber. The amount of air to be generated is increased from that in the low-load power generation operation being performed, and the amount of power generation air supplied from the power generation air flow rate adjustment unit 45 to the power generation air header 19 is reduced from that in the low-load power generation operation. .

That is, as the temperature of the power generation chamber 10 increases due to this cleaning mode operation, the temperature of the fuel cell assembly 12 increases and is supplied from the power generation air header 19 to the air electrode of each fuel cell unit 16. Since the amount of power generation air is reduced, the cooling effect of the power generation air on each fuel cell unit 16 is reduced, and the temperature of the fuel cell assembly 12 can be kept high. As a result, sulfur adhering to each fuel cell unit 16 can be removed.
Also, in the n-th (n ≧ 2) cleaning mode operation, whether the power generation operation time τn from the time when the previous cleaning mode operation ends to the time when the next cleaning mode operation starts reaches 5000 hours, Alternatively, when the cell voltage reaches the lower limit voltage value V0 before the power generation operation time τn reaches 5000 hours, the cleaning mode operation is performed regardless of the power generation amount by the power generation operation so far.

  According to the cleaning mode operation of the second example according to the present embodiment described above, the low load power generation operation is performed at a temperature below the predetermined temperature within the temperature range in which the temperature of the power generation chamber is capable of steady power generation operation by the fuel cell module. Even if the fuel cell module 2 generates power, the low-load power generation operation time after the start-up operation is finished and the low-load power generation operation is started and the previous cleaning mode operation are performed regardless of the amount of power generated by the fuel cell module 2. When the power generation operation time after finishing and restarting the low load power generation operation reaches a predetermined time (for example, 5000 hours) or when the cell voltage during the power generation operation reaches a predetermined lower limit voltage value, the control unit 60 The temperature of the power generation chamber (T) is forcibly increased to a predetermined temperature (for example, 950 ° C.) higher than the temperature of the power generation chamber in which the low load power generation operation is performed within the steady power generation operation temperature range. Mode operation is executed. For this reason, even when the cleaning mode operation is being performed, it is possible to perform a steady power generation operation and to effectively remove sulfur adhering to the fuel cell assembly 12. Inactivation of the battery cell can be prevented. Further, since the cleaning mode operation is performed by increasing the temperature of the power generation chamber within a temperature range (850 ° C. to 950 ° C.) in which a steady power generation operation is possible, the fuel by heating accompanying the temperature increase of the power generation chamber 10 The burden on the battery cell unit 16 can also be minimized.

Next, the operation during the cleaning mode operation of the third example of the solid oxide fuel cell (SOFC) according to the present embodiment will be described with reference to FIG.
FIG. 8 is a time chart showing the operation during the cleaning mode operation of the third example of the solid oxide fuel cell (SOFC) according to the present embodiment.

  As shown in FIG. 8, the cleaning mode operation of the third example by the solid oxide fuel cell (SOFC) 1 of this embodiment is a steady power generation operation temperature region where the power generation chamber temperature (T) is 850 ° C. or more and 950 ° C. or less. And the cell voltage (V) is larger than the lower limit voltage value V0 (= 0.74V), and is executed under predetermined conditions when a steady power generation operation is performed. ing.

More specifically, first, after the start-up operation of the fuel cell module 2 described with reference to FIG. 3, the power generation operation time τ1 (=) from the start of the power generation operation at time t200 to the start of the cleaning mode operation at time t201. 5000 hours) and the lower limit voltage value V0 (= 0.74V) of the cell voltage (V) are set in advance as reference values for determining whether or not to start the cleaning mode operation.
In addition, when the power generation operation time τ1 from when the power generation operation is started at time t200 to when the first cleaning mode operation is started at time t201 and when the nth (n ≧ 2) cleaning mode operation is executed, the previous time The power generation operation is restarted from the time when the cleaning mode operation is completed, and the power generation operation time τn from the time when the next cleaning mode operation is started is changed according to the state of the power generation operation.

  More specifically, in order to grasp the power generation operation state, the power generation chamber temperature detected by the power generation chamber temperature sensor 92 during the power generation operation and the integrated value based on the operation time, or the power generation chamber temperature (T) is 850 ° C. or more and 950 Typically, the actual operation history of the fuel cell module 2 such as the accumulated time during which the power generation operation is performed under a low load temperature condition that is less than a predetermined temperature (less than 900 ° C.) within the steady power generation operation temperature range that is equal to or lower than ° C. The power generation operation state is quantified by a specific amount based on the indicated quantitative value. Based on these quantified values, the power generation operation time τ1 from the start of the power generation operation to the start of the first cleaning mode operation or the nth (n ≧ 2) cleaning mode operation is executed. In this case, it is determined whether or not to change the power generation operation time τn from the end of the previous cleaning mode operation to the start of the next cleaning mode operation.

  As an example, FIG. 8 shows an example in which the first cleaning mode operation is started at time t201, the first cleaning mode operation ends at time t202 after a predetermined time, and the power generation operation time τ2 (= 5000 hours) has passed again at time t202. The executed steady power generation operation is performed in a state where the temperature of the power generation chamber is higher than that of the steady power generation operation from time t200 to t201. As a result, the sulfur adhering to the fuel cell assembly 12 is more effective at the time when the second cleaning mode operation is completed at time t204 than when the first cleaning mode operation is completed at time t202. Therefore, the power generation operation time τ3 from the end of the second cleaning mode operation at time t204 to the start of the third cleaning mode operation at time t205 is changed from a predetermined 5000 hours to 7000 hours. It has changed.

  According to the cleaning mode operation of the third example according to the present embodiment described above, the amount of sulfur actually attached to the fuel cell assembly 12 varies depending on the history of the power generation operation of the fuel cell module 2, but the nth cleaning is performed. Since the power generation operation time τn before the mode operation can be changed based on the operation history (power generation operation time and / or the temperature of the power generation chamber 10) in which the power generation operation by the fuel cell module 2 is performed, the actual sulfur adhesion amount It is possible to appropriately set the time interval between the cleaning mode operations corresponding to. Moreover, the burden on the fuel cell unit 16 due to heating accompanying the temperature rise of the power generation chamber 10 can be minimized.

Next, the operation of the fourth example of the solid oxide fuel cell (SOFC) according to the present embodiment during the cleaning mode operation will be described with reference to FIG.
FIG. 8 is a time chart showing the operation during the cleaning mode operation of the fourth example of the solid oxide fuel cell (SOFC) according to the present embodiment.

As shown in FIG. 9, in the cleaning mode operation of the fourth example by the solid oxide fuel cell (SOFC) 1 of this embodiment, first, after the start-up operation of the fuel cell module 2 described with reference to FIG. From the start of the low load power generation operation to the time t301, the power generation chamber temperature (T) is within a temperature range below a predetermined temperature (T1) within a steady power generation operation temperature range in which the power generation chamber temperature (T) is 850 ° C. or more and 950 ° C. or less The low load power generation operation is executed with (V) being larger than the lower limit voltage value V0 (= 0.74V).
Next, from time t301 to time t302, the steady power generation operation is performed in a predetermined temperature region (T1 <T ≦ T2) where the power generation chamber temperature (T) is higher than the low load power generation operation from time t300 to t301. The first cleaning mode operation is executed at time t302.
Here, the power generation operation time τ1 from the start of the low load power generation operation at time t300 to the execution of the first cleaning mode operation is predetermined as 5000 hours before the operation, but from time t300 to t301. Since the low load power generation operation is executed, the predetermined time (5000 hours) is changed to a shorter time (4000 hours) in order to accelerate the initial cleaning mode operation.

In addition, after the first cleaning mode operation is executed for a predetermined time (2 to 3 hours) at time t302, the cleaning mode operation is ended at time t303, and the temperature is again below the predetermined temperature (T1) within the steady power generation operation temperature region. A low load power generation operation is performed in the region.
At time t304, the second cleaning mode operation is executed. At times t303 to 304, only the low load power generation operation is executed. Therefore, in order to accelerate the start of the second cleaning mode operation, the first cleaning mode operation is performed. The power generation operation time τ2 from the end to the start of the second cleaning mode operation is changed from a predetermined time (5000 hours) to a shorter time (3000 hours).

Further, after the second cleaning mode operation is performed for a predetermined time (2 to 3 hours) at time t304, the cleaning mode operation is terminated at time t305, and the power generation chamber temperature (T) from time t305 to t306 is constant power generation operation. The steady power generation operation is executed at a predetermined temperature T3 (≧ T2) in the temperature region, and the third cleaning mode operation is executed at time t306.
Here, at times t305 to 306, the steady power generation operation is executed at a temperature at which the power generation chamber temperature (T) is higher than that between times t300 to t302 and times t303 to t304. Therefore, after the second cleaning mode operation is completed. The power generation operation time τ3 until the third cleaning mode operation is started is longer than the times τ1 and τ2 until the first and second cleaning mode operations are executed.

  That is, in the cleaning mode operation of the fourth example according to the present embodiment, the power generation chamber temperature (T) is steady in the power generation operation in which the power generation chamber temperature (T) other than the cleaning mode operation is executed within the steady power generation operation temperature region. The higher the proportion of low-load power generation operation performed in a relatively low temperature region within the power generation operation temperature region in the operation history of the fuel cell module 2, the first cleaning mode operation starts after the power generation operation starts. The time τn until the nth (n ≧ 2) cleaning mode operation starts after the end of the previous cleaning mode operation τ1 or the previous cleaning mode operation is shorter than a predetermined time (5000 hours) It can be changed to.

  According to the cleaning mode operation of the fourth example according to this embodiment described above, the time during which the fuel cell assembly 12 is exposed to a higher temperature as the ratio of the low load power generation operation to the operation history by the fuel cell module 2 is higher. However, the amount of sulfur attached to the fuel cell unit 16 also increases, but the power generation operation time τ1 from the start of the power generation operation to the start of the first cleaning mode operation or the previous cleaning mode operation ends. The time τn until the nth (n ≧ 2) cleaning mode operation starts is changed to a shorter time than the predetermined time (5000 hours), and the execution of the cleaning mode operation is accelerated. Therefore, it is possible to perform an appropriate operation according to the amount of sulfur attached to the actual fuel cell unit 16.

Next, the operation during the cleaning mode operation of the fifth example of the solid oxide fuel cell (SOFC) according to the present embodiment will be described with reference to FIG.
FIG. 8 is a time chart showing the operation during the cleaning mode operation of the fifth example of the solid oxide fuel cell (SOFC) according to the present embodiment.

  As shown in FIG. 10, in the cleaning mode operation of the fifth example by the solid oxide fuel cell (SOFC) 1 of this embodiment, first, after the start-up operation of the fuel cell module 2 described with reference to FIG. The power generation operation is started and the power generation operation time τn (= 5000 hours) and the lower limit voltage value V0 (= 0.76V) of the cell voltage (V) before starting the n-th (n ≧ 1) cleaning mode operation at time tn. ) Is determined in advance as a reference value for determining whether or not to start the cleaning mode operation.

Furthermore, the duration of continuing the nth cleaning mode operation from the start of the nth (n ≧ 1) cleaning mode operation at time tn until the end of the nth cleaning mode operation at time t (n + 1). Is determined in advance for a predetermined time (2 to 3 hours).
On the other hand, when the cell voltage has increased to the predetermined voltage (V1) at time t (n + 1) during the n-th cleaning mode operation, the control unit 60 sends a signal from the power state detection sensor 76. It is received and judged that sulfur adhering to the fuel cell assembly 12 has been removed and the cell voltage has been recovered, regardless of a predetermined duration (2 to 3 hours) of operation in a predetermined cleaning mode. The nth cleaning mode operation is forcibly terminated.

  According to the cleaning mode operation of the fifth example according to this embodiment described above, when the voltage of the fuel cell module reaches a predetermined voltage even if the cleaning mode operation is continued, a predetermined continuation of the predetermined cleaning mode operation is performed. Regardless of the time, the cleaning mode operation is forcibly terminated, so that it is possible to prevent the fuel cell assembly 12 from being unnecessarily exposed to a high temperature and to prevent deterioration of the fuel cell unit 16.

  In the cleaning mode operation of the first to fifth examples according to the present embodiment described above, the power generation time τn before executing the n-th (n ≧ 1) cleaning mode operation reaches a predetermined time, or As a means for forcibly increasing the power generation chamber temperature (T) when the cell voltage reaches a predetermined voltage, the controller 60 supplies the fuel gas supply means (fuel flow rate adjustment unit 38) and the power generation air supply means (power generation). The fuel gas supplied from the fuel flow rate adjusting unit 38 to the reformer 20 is increased by a signal sent to the air flow rate adjusting unit 45) and supplied to the air header 19 for power generation from the air flow rate adjusting unit 45 for power generation. However, the present invention is not limited to this, and the fuel supplied from the fuel flow rate adjustment unit 38 to the reformer 20 is described. The cleaning mode operation may be executed by either increasing the amount of gas or reducing the amount of power generation air supplied from the power generation air flow rate adjustment unit 45 to the power generation air header 19. .

  Further, in the present embodiment, by separately providing a heating means such as a heater or a burner for heating the fuel gas supplied to the reformer 20 and the power generation air supplied to the power generation air header 19, a cleaning mode is provided. When operating, you may devise so that a power generation room temperature may be raised more effectively.

  Further, in addition to the cleaning mode operation of the first to fifth examples according to the present embodiment, the fuel cell module 2 generates power for a long period of time, and a predetermined aging time of the fuel cell unit 16 (for example, 40000 hours). In consideration of the fact that sulfur tends to adhere to the fuel cell unit 16 over time, the longer the aging time during which the power generation operation by the fuel cell module 2 is performed, the longer the previous cleaning mode operation ends. The cleaning mode operation may be executed by setting the power generation time interval until the next cleaning mode operation is started. Thus, the fuel cell assembly 12 that has passed over time can be appropriately operated according to the amount of sulfur adhering to the actual fuel cell unit 16 by advancing the execution of the cleaning mode operation. .

  Furthermore, in addition to the cleaning mode operations of the first to fifth examples according to the present embodiment, the cleaning mode operation may be forcibly executed by manually operating the controller 60 as appropriate. Thereby, even if a failure occurs in the desulfurization process of the fuel gas, such as a failure of the desulfurizer 36, the sulfur adhering to the fuel cell assembly 12 can be reliably removed as appropriate.

  In the above-described embodiment, an example in which the desulfurizer 36 is provided on the upstream side of the fuel flow rate adjustment unit 38 has been described as an example. However, the present invention is not limited to such a configuration. It may be provided on the downstream side of the unit 38.

DESCRIPTION OF SYMBOLS 1 Solid oxide type fuel cell 2 Fuel cell module 4 Auxiliary unit 8 Sealed space 10 Power generation chamber 12 Fuel cell assembly 14 Fuel cell stack 16 Fuel cell unit (solid oxide fuel cell)
DESCRIPTION OF SYMBOLS 18 Combustion chamber 19 Power generation air header 20 Reformer 21 Preheater 22 Evaporator 23 Fuel gas dispersion chamber 24 Water supply source 26 Pure water tank 28 Water flow rate adjustment unit 30 Fuel supply source 36 Desulfurizer 38 Fuel flow rate adjustment unit (fuel) Gas supply means)
40 Air supply source 44 Reforming air flow rate adjusting unit (reforming air supply means)
45 Air flow adjustment unit for power generation (air supply means for power generation)
46 1st heater 48 2nd heater 50 Hot water production apparatus 52 Control box 54 Inverter 60 Control part 62 Operation apparatus 64 Display apparatus 66 Alarm apparatus 76 Power condition detection sensor 92 Power generation room temperature sensor 100 Outside temperature sensor

Claims (10)

A solid oxide fuel cell that generates electricity by reacting fuel gas and air,
A fuel cell assembly that is disposed in a power generation chamber in the fuel cell module and includes a plurality of solid electrolyte fuel cells;
A desulfurizer for removing sulfur contained in the fuel gas;
A reformer for reforming fuel gas and supplying the fuel cell assembly to the reformer;
Fuel gas supply means for supplying fuel gas to the reformer;
Power generation air supply means for supplying power generation air to the fuel cell assembly;
Controlling the power generation air supply means to reduce the amount of power generation air supplied from the power generation air supply means to the fuel cell assembly when the predetermined condition is reached, and / or The fuel gas supply means is controlled to increase the amount of fuel gas supplied from the fuel gas supply means to the fuel cell assembly, and the temperature of the power generation chamber is forcibly increased to a temperature higher than 950 ° C. A controller that performs a cleaning mode operation for removing sulfur that has not been completely desulfurized by the desulfurizer and has adhered to the fuel cell assembly;
A solid oxide fuel cell comprising:   2. The solid oxide fuel cell according to claim 1, wherein the predetermined condition for the control unit to execute the cleaning mode operation is when a predetermined power generation operation time has elapsed.   2. The solid oxide fuel cell according to claim 1, wherein the predetermined condition for the control unit to execute the cleaning mode operation is when the voltage of the fuel cell reaches a predetermined voltage.   4. The controller according to claim 1, wherein the controller performs the cleaning mode operation by raising the temperature of the power generation chamber to a temperature higher than a temperature range in which the fuel cell module can perform a steady power generation operation. The solid oxide fuel cell according to Item.   When the low load power generation operation is performed at a temperature lower than a predetermined temperature within a temperature range in which the temperature of the power generation chamber is capable of steady power generation operation by the fuel cell module, the control unit The solid electrolyte fuel according to any one of claims 1 to 3, wherein the cleaning mode operation is performed by raising the temperature of the fuel cell to a temperature equal to or higher than the predetermined temperature within a temperature range where the steady power generation operation is possible. battery.   The solid oxide fuel cell according to claim 2, wherein the control unit changes the predetermined power generation operation time for executing the cleaning mode operation based on a history of operation by the fuel cell module.   The control unit is configured to set the predetermined power generation operation time for executing the cleaning mode operation to a temperature lower than a predetermined temperature within a temperature range in which the temperature of the power generation chamber is capable of steady power generation operation by the fuel cell module. The solid oxide fuel cell according to claim 6, wherein the time is changed to a shorter time as the proportion of the low load power generation operation in the history of operation by the fuel cell module is higher.   The control unit executes the cleaning mode operation for a predetermined duration, and if the voltage of the fuel cell reaches a predetermined voltage during the execution of the cleaning mode operation, even within the predetermined duration. 8. The solid oxide fuel cell according to claim 1, wherein the cleaning mode operation is forcibly terminated.   The control unit sets the predetermined power generation operation time, which is a condition for executing the cleaning mode operation, to a shorter time as the aging time during which the power generation operation by the fuel cell module is performed is longer. 9. The solid oxide fuel cell according to any one of 8 above.   2. The solid electrolyte according to claim 1, wherein the predetermined condition for the control unit to execute the cleaning mode operation is a manual operation, and the control unit forcibly executes the cleaning mode operation by the manual operation. Type fuel cell.

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