JP2012009206A - Power generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a technique capable of preventing a burner from being misfired in a power generator using a solid oxide fuel cell.
A power generator includes a reformer, a fuel battery cell, an off-gas combustion unit, a burner, and a control device. The reformer 26 reforms a mixed gas of fuel gas and water vapor into a reformed gas. The fuel cell 25 is a solid oxide fuel cell 25, and generates electricity by reacting the reformed gas with cathode air. The off gas combustion unit 27 burns off gas from the fuel cell 25 and heats the reformer 26 with the combustion heat. The burner 64 burns fuel gas and heats the reformer 26 with the combustion heat. The control device 100 simultaneously executes a process for reducing the supply amount of the fuel gas and air supplied to the burner 64 and a process for reducing the supply amount of the cathode air supplied to the fuel cell 25 when the power generation device 2 is started. do not do.
[Selection] Figure 2

Description

  The present invention relates to an apparatus for generating electricity by a fuel cell using a solid oxide.

  Patent Document 1 discloses an example of a power generation device using a fuel cell using a solid oxide. However, Patent Document 1 has not been disclosed yet. The power generation device of Patent Document 1 includes a reformer, a fuel battery cell, and a burner. The reformer reforms a mixed gas of fuel gas and water vapor into a reformed gas. The fuel cell generates electricity by reacting the reformed gas with an aerobic gas. The burner burns fuel gas and heats the reformer with the combustion heat. The power generation device of Patent Document 1 has succeeded in causing the reformer to reach the operating temperature before the fuel cell reaches the operating temperature.

Japanese Patent Application No. 2009-115299

In some cases, the power generation device of Patent Document 1 is operated in the following order (a) to (f).
(A) While supplying an aerobic gas to a fuel battery cell, a fuel gas and an aerobic gas are supplied to a burner, and a fuel gas is burned. The reformer is heated by the combustion heat of the burner. The aerobic gas supplied to the fuel cell is supplied after being preheated by the combustion heat of the burner, and heats the fuel cell. The reformer rises in temperature faster than the fuel cell.
(B) Before the reformer reaches a suitable operating temperature and reaches a predetermined temperature, water is supplied to the reformer and heated in the reformer to generate steam.
(C) In order to prevent overheating of the reformer, the supply amounts of fuel gas and aerobic gas supplied to the burner are reduced. At the same time, the supply amount of the aerobic gas supplied to the fuel cells is decreased in order to facilitate ignition of off gas to be described later.
(D) When the reformer reaches a suitable operating temperature, further fuel gas is supplied to the reformer. In the reformer, a mixed gas of the supplied fuel gas and water vapor generated in the reformer is reformed into a reformed gas.
(E) The reformed gas is supplied to the fuel cell that has reached the operating temperature to generate power, and the excess reformed gas (off-gas) that has not been used for power generation is ignited and burnt at the tip of the fuel cell. Let Off-gas combustion heat is used to heat the reformer and the fuel cell.
(F) In order to promote power generation and off-gas combustion, the supply amount of aerobic gas supplied to the fuel cell is increased again.

  However, in the above (c), if the supply amount of the aerobic gas supplied to the fuel cell and the supply amount of the aerobic gas supplied to the burner are decreased at the same time, the accommodation chamber for containing the fuel cell is rapidly changed. It has been found that the pressure is reduced. Therefore, even if an instruction to reduce the supply amount of the fuel gas supplied to the burner at the same time is given, a negative pressure is also generated in the fuel gas supply path due to the sudden pressure reduction in the above-described storage chamber, and the fuel gas is temporarily It has also been found that there may be a case where a significantly larger amount is supplied than the indicated value. As a result, it has been found that the amount of fuel gas supplied to the burner becomes too large compared to the amount of aerobic gas supplied to the burner, and the burner may misfire. In this specification, the technique for implement | achieving the electric power generating apparatus which can prevent misfire of a burner is disclosed.

In the present specification, a power generation device using a solid oxide fuel cell is disclosed. The power generation device includes a reformer, a fuel battery cell, a combustion unit, a burner, and a control device. The reformer reforms a mixed gas of fuel gas and water vapor into a reformed gas. The fuel cell is a solid oxide fuel cell and generates electricity by reacting the reformed gas with an aerobic gas. The combustion unit burns off-gas from the fuel battery cell and heats the reformer with the combustion heat. The burner burns fuel gas and heats the reformer with the combustion heat.
The control device is at least when starting the power generation device,
(1) a processing procedure for supplying an aerobic gas to a fuel cell;
(2) Supplying fuel gas and aerobic gas to the burner to burn the fuel gas and heating the reformer with the combustion heat;
(3a) A processing procedure for reducing the supply amount of fuel gas and aerobic gas supplied to the burner after the processing procedures of (1) and (2) above;
(3b) After the processing procedures (1) and (2) above, execute a processing procedure for reducing the supply amount of the aerobic gas supplied to the fuel cell,
The processing procedures (3a) and (3b) are executed at different timings.

As a result of the diligent research by the present inventors, when the decrease in the supply amount of the aerobic gas supplied to the fuel cell and the decrease in the supply amount of the fuel gas and the aerobic gas supplied to the burner are not performed simultaneously, It has been found that sudden pressure reduction in the accommodation chamber is suppressed as compared to the case where these are performed simultaneously. In that case, it has also been found that the situation in which the fuel gas is supplied to the burner much more than the indicated value is less likely to occur. The above power generator is created based on this knowledge.
In the above power generation device, the control device has different timings for the processing procedure for reducing the supply amount of the fuel gas and the aerobic gas supplied to the burner and the processing procedure for reducing the supply amount of the aerobic gas supplied to the fuel cell. Run with. That is, the two processing procedures that cause the decompression of the storage chamber are not executed simultaneously. In order to have this configuration, in the power generation device described above, rapid pressure reduction in the accommodation chamber is suppressed, and a situation in which fuel gas is supplied to the burner significantly more than the indicated value is less likely to occur. Therefore, the misfire of the burner can be prevented.

  Further, the processing procedure (3b) is preferably a processing procedure for gradually reducing the supply amount of the aerobic gas supplied to the fuel cell. Since this configuration is provided, pressure reduction in the accommodation chamber can be performed in stages. Rapid decompression in the storage chamber is further suppressed. Accordingly, it is possible to more reliably prevent the burner from being misfired.

  The control device executes the processing procedure of (3b) after the processing procedure of (3a) is executed and the supply amount of the fuel gas and the aerobic gas supplied to the burner is reduced to a predetermined amount. May be. In this case, it is possible to prevent overheating of the reformer at an early stage by reducing the supply amount of the fuel gas and the aerobic gas supplied to the burner in advance. Even when the chamber is depressurized as the supply amount of the aerobic gas supplied to the fuel cell decreases, the supply amount of the fuel gas supplied to the burner has already been reduced to a predetermined amount. A situation in which a large amount of fuel gas is supplied is less likely to occur. Therefore, the misfire of the burner can be prevented.

  The control device executes the processing procedure (3a) after the processing procedure (3b) is executed and the supply amount of the aerobic gas supplied to the fuel cell is reduced to a predetermined amount. May be. In this case, the off-gas can be ignited at an early stage by reducing the supply amount of the aerobic gas supplied to the fuel battery cell to a predetermined amount in advance. From an early stage, off-gas combustion heat can be used for continuous heating of the reformer.

1 is a front sectional view showing a power generator according to a first embodiment. Side surface sectional drawing which shows the electric power generating apparatus of 1st Example. The flowchart which shows the operation | movement at the time of starting of the electric power generating apparatus of 1st Example. The graph which shows the supply_amount | feed_rate of the fuel gas and air with respect to a burner, and the supply_amount | feed_rate of cathode air in 1st Example. The graph which shows the supply_amount | feed_rate of the fuel gas and air with respect to a burner, and the supply_amount | feed_rate of cathode air in 2nd Example.

The main features of the embodiments described below are listed.
(Embodiment 1) The burner is a combustion burner having a form in which fuel gas is subjected to surface combustion, for example, an infrared burner including a heat-resistant ceramic plate.
(Embodiment 2) The burner stops when both the reformer and the fuel cell reach a suitable operating temperature.
(Mode 3) The power generation device includes a heat exchanger that performs heat exchange between the exhaust gas passing through the exhaust gas passage and the cathode air passing through the cathode air passage.

(First embodiment)
A first embodiment will be described. FIG. 1 is a diagram schematically illustrating a front cross-section of the power generator according to the present embodiment, and FIG. 2 is a diagram schematically illustrating a side cross-section of the power generator. As shown in FIG.1 and FIG.2, the electric power generating apparatus 2 is provided with the box-shaped main body casing 4 by which all six surfaces were formed with the heat insulating material. In the main casing 4, a storage chamber 10 that stores a plurality of cell stacks 24 and the like in order from the inside, an exhaust gas passage 40 for exhausting exhaust gas generated in the storage chamber 10 to the outside, and used for power generation. A cathode air passage 50 through which oxygen gas (air) passes is provided. As shown in FIG. 2, a burner 64 is provided on a part of the peripheral wall of the main casing 4. A control device 100 is provided outside the main casing 4.

  The storage chamber 10 is a space formed inside the inner casing 18 and the two baffle plates 20. The inner casing 18 is a box-shaped member that opens upward. The upper end of the baffle plate 20 is attached to the inner upper surface of the main body casing 4, and the lower end is inserted into the inner casing 18. An exhaust gas passage hole 22 is opened near the upper end of the baffle plate 20 so that high-temperature exhaust gas generated in the storage chamber 10 can be sent from the storage chamber 10 to the exhaust gas passage 40.

  A plurality of cell stacks 24, a reformer 26, a reformed gas supply pipe 28, a reformed gas chamber 30, an introduction pipe 32, and a manifold 34 are accommodated in the accommodation chamber 10. Each cell stack 24 is formed by stacking a plurality of fuel battery cells 25 in a rod shape. Although not shown, the cell stack 24 is composed of a plurality of fuel cells 25 in which the peripheral surface of the support substrate is covered with a fuel electrode, a solid electrolyte layer, and an oxygen electrode. In the cell stack 24, an oxygen electrode and a fuel electrode of adjacent fuel cells 25 are electrically connected via an interconnector and a current collecting member, whereby a large number of fuel cells 25 are connected in series. Is formed.

  A plurality of reformed gas passages penetrating in the direction in which the cell stack 24 extends (the vertical direction in FIG. 1) are formed in parallel inside the fuel electrode of the fuel cell 25, although not shown. The fuel cell 25 generates electric power by reacting the supplied reformed gas with the surrounding aerobic gas (air) when a reformed gas described later is supplied to the reformed gas passage. In this embodiment, the reformed gas is composed of hydrogen and carbon monoxide, and air is used as the aerobic gas. Hereinafter, the air supplied to the fuel cell 25 is referred to as cathode air. An exhaust gas composed of water vapor and carbon dioxide is generated by the power generation reaction. Since this power generation reaction is accompanied by heat generation, the generated exhaust gas has a high temperature.

  In the fuel battery cell 25, the fuel electrode is porous and made of nickel / YSZ cermet (mixed sintered body) containing nickel (Ni) as one component. The solid electrolyte layer is dense and consists of a mixture of zirconia (ZrO2) and yttria (Y2O3). The oxygen electrode is porous and is made of LSM (La1-xSrxMnO3) which is a perovskite oxide. The interconnector is made of a conductive ceramic.

  At the upper end portion of each fuel cell 25, the reformed gas passage is opened, and surplus reformed gas that has not been consumed for power generation, so-called off-gas, is released. Hereinafter, the reformed gas discharged from the upper end portion of each fuel cell 25 without being consumed for power generation is widely referred to as “off gas”. A spark electrode (not shown) is disposed near the upper end of each cell stack 24. When the spark electrode is subjected to spark discharge, the offgas can be ignited and the offgas can be burned. Hereinafter, the upper end of each cell stack 24 may be referred to as the off-gas combustion unit 27 in some cases.

  As shown in FIGS. 1 and 2, each cell stack 24 is erected on a manifold 34 provided at a lower portion in the storage chamber 10. In this embodiment, as shown in FIG. 1, the cell stacks 24 are arranged in three rows. However, the number of the cell stacks 24 is not limited to three rows, and may be larger or smaller.

  The manifold 34 has a reformed gas flow path (not shown) inside, and a plurality of pores for supplying the reformed gas flowing inside the manifold 34 into the reformed gas passage of the fuel cell 25 on the upper surface. It is open. In the present embodiment, the reformed gas chamber 30 is provided below the manifold 34 via the introduction pipe 32. For this reason, the reformed gas supplied from the reformer 26 through the reformed gas supply pipe 28 is supplied to the manifold 34 through the reformed gas chamber 30 and the introduction pipe 32. By supplying the reformed gas from the reformer 26 to the manifold 34 via the reformed gas chamber 30 and the introduction pipe 32, it becomes easier to supply the reformed gas evenly to each fuel cell 25.

  The reformer 26 steam-reforms the fuel gas to generate a reformed gas used for the power generation reaction in the fuel battery cell 25. The reformer 26 is disposed above the upper end portion (off gas combustion portion 27) of the cell stack 24 so that the combustion heat of the off gas burned at the tip end portion of the cell stack 24 can be used for reforming. It is.

  The reformer 26 is provided with a fuel gas supply pipe 46 for supplying fuel gas from the outside, and a water supply pipe 48 for supplying water (pure water) that is a source of water vapor. The fuel gas supply pipe 46 is provided with an adjustment valve 46 a for adjusting the amount of fuel gas supplied to the reformer 26. Further, the water supply pipe 48 is provided with an adjustment valve 48 a for adjusting the amount of water supplied to the reformer 26. A vaporizing mechanism (not shown) is provided in the reformer 26. The vaporization mechanism generates water vapor by heating the supplied water. In this embodiment, for example, a gas mainly composed of methane is used as the fuel gas. An example of such a gas is city gas.

  In the reformer 26, a flat box-shaped casing made of metal and a meandering path are formed, and the reforming catalyst is filled in the path. The mixed gas of the water vapor generated by the vaporization mechanism in the reformer 26 and the fuel gas supplied from outside is reformed from hydrogen and carbon monoxide by the reforming catalyst while passing through the reformer 26. The gas is reformed. Since this reforming reaction is endothermic, the reformer 26 needs to be heated to a suitable temperature. The preferred reforming temperature of the fuel gas containing methane as a main component as in this embodiment is 400 ° C. or higher (more preferably 600 ° C. or higher). The reformer 26 is preferably heated to 400 ° C. or higher. The reformed gas reformed by the reformer 26 is sent to the reformed gas chamber 30 through the reformed gas supply pipe 28, and passes through the reformed gas chamber 30, the introduction pipe 32, and the manifold 34 to each fuel. It is fed into the reformed gas passage of the battery cell 25.

  The exhaust gas passage 40 is provided outside the storage chamber 10. The exhaust gas passage 40 is a passage through which high-temperature exhaust gas generated by the power generation reaction and off-gas combustion in the fuel battery cell 25 passes. As shown in FIG. 1, the exhaust gas passage 40 is a space provided between the inner casing 18 and the outer casing 51, and is provided so as to cover the bottom surface and the pair of side surfaces of the storage chamber 10.

  The outer casing 51 is a box-shaped member that is open at the top. As shown in FIG. 1, the upper end of the side wall of the outer casing 51 is bent inward and further bent toward the bottom surface to form an inner wall 51a, an outer wall 51b, and an upper edge 51c. The inner wall 51a is provided by being inserted into the inner casing 18.

  An exhaust gas passage hole 52 is opened near the upper end of the inner wall 51a, and communicates with the exhaust gas passage hole 22 of the baffle plate 20 by a duct 54. Accordingly, the exhaust gas generated in the storage chamber 10 is supplied from the exhaust gas passage hole 22 of the baffle plate 20 through the duct 54 and the exhaust gas passage hole 52 into the exhaust gas passage 40. The outer wall 51b is provided with a plurality of fins 56 for heat exchange. Each fin 56 is provided so that half protrudes into the exhaust gas passage 40 and the other half protrudes into the cathode air passage 50. An exhaust gas exhaust pipe 58 communicating with the outside is provided on the bottom surface 51d, and exhaust gas that has passed through the exhaust gas passage 40 is exhausted to the outside. Accordingly, the high-temperature exhaust gas generated by the power generation reaction and off-gas combustion in the fuel cell 25 heats the reformer 26, and then passes through the duct 54 from the exhaust gas passage hole 22 of the baffle plate 20 and the upper part of the exhaust gas passage 40. Flow into. The exhaust gas flowing in from the upper part of the exhaust gas passage 40 flows downward in the exhaust gas passage 40 while performing heat exchange with the fins 56. The temperature of the exhaust gas is lowered by heating the reformer 26 and heat exchange by the fins 56. The exhaust gas after the heat exchange in the fins 56 is discharged from the exhaust gas discharge pipe 58 on the bottom surface 51 d of the exhaust gas passage 40.

  The cathode air passage 50 is provided outside the exhaust gas passage 40 described above. The cathode air passage 50 is a passage for allowing cathode air used for power generation reaction and off-gas combustion in the fuel cell 25 to pass therethrough. As shown in FIG. 1, the cathode air passage 50 is formed between the outer wall 51 b, the upper edge 51 c, the bottom surface 51 d of the outer casing 51 and the inside of the main casing 4, and the inner wall 51 a of the outer casing 51 and the baffle plate 20. It is the space provided between. As described above, half of the plurality of fins 56 provided on the outer wall 51 b protrudes into the cathode air passage 50. A cathode air supply pipe 60 communicating with the outside is provided on the bottom surface of the main casing 4 so that the cathode air can be supplied into the cathode air passage 50 from the outside. The cathode air supply pipe 60 is provided with an adjustment valve 60a for adjusting the supply amount of the cathode air. The cathode air supplied into the cathode air passage 50 flows upward in the cathode air passage 50 while performing heat exchange with the fins 56. The cathode air is heated by the heat exchange. The cathode air after the heat exchange passes through the space between the upper end edge 51 c of the outer casing 51 and the inside of the main casing 4 and between the inner wall 51 a of the outer casing 51 and the baffle plate 20, and the accommodating chamber 10. Supplied in. The cathode air supplied into the storage chamber 10 is used for a power generation reaction in the fuel battery cell 25 and off-gas combustion. Further, since the cathode air supplied into the storage chamber 10 is heated to a high temperature by the heat exchange described above, it is also used for heating the fuel cell 25.

  The burner 64 is provided in a through-hole portion 66 formed in a side portion of the reformer 26 of the main casing 4 so that the reformer 26 can be heated from the outlet side. The outlet side referred to here is the reformed gas supply pipe 28 side. The burner 64 of the present embodiment is a combustion burner having a form in which fuel gas is subjected to surface combustion. An example of such a combustion burner is an infrared burner provided with a heat-resistant ceramic plate. The through-hole portion 66 of the main casing 4 is provided with a combustion air supply pipe 68 that supplies combustion air to the burner 64 and a gas supply pipe 70 that supplies fuel gas to the burner 64. The combustion air supply pipe 68 is provided with an adjustment valve 68 a that adjusts the amount of combustion air supplied to the burner 64. The gas supply pipe 70 is provided with an adjustment valve 70 a that adjusts the amount of fuel gas supplied to the burner 64. The fuel gas supplied to the burner 64 is the same gas as the fuel gas supplied to the reformer 26.

  The control device 100 is electrically connected to the above-described components provided in the main casing 4 and controls their operations.

  Next, the operation at the time of starting the power generation device 2 will be described with reference to FIG. It is a flowchart which shows the operation | movement at the time of starting of the electric power generating apparatus 2 with reference to FIG. When the power generation device 2 is activated, the processes described below are sequentially executed.

  When the power generation device 2 is activated, the control device 100 opens the regulating valve 60a and starts supplying cathode air to the fuel cell 25 (S2). Specifically, cathode air is supplied into the cathode air passage 50 through the cathode air supply pipe 60 by opening the regulating valve 60a. The air supplied into the cathode air passage 50 is supplied to the fuel cells in the storage chamber 10 through the cathode air passage 50.

  Next, the control device 100 operates the burner 64 (S4). Specifically, the control device 100 opens the regulating valve 68a and the regulating valve 70a to supply fuel gas and air for burner combustion to the burner 64, and ignites the supplied combustion gas to start combustion. When combustion of the fuel gas is started by the burner 64, the combustion exhaust gas generated by the combustion is applied to the reformer 26, and the reformer 26 is heated. At this time, the temperature increase width per unit time of the reformer 26 is larger than the temperature increase width per unit time of the fuel cell 25. The temperature of the reformer 26 rises faster than the temperature of the fuel battery cell 25.

  The exhaust gas generated by the combustion of the burner 64 heats the reformer 26, and then is mixed with the cathode air supplied to the fuel cell 25 in S2, and passes through the duct 54 from the exhaust gas passage hole 22 of the baffle plate 20. It flows into the upper part of the exhaust gas passage 40. The exhaust gas flowing in from the upper part of the exhaust gas passage 40 flows downward in the exhaust gas passage 40 while performing heat exchange with the fins 56. The temperature of the exhaust gas is lowered by heating the reformer 26 and heat exchange by the fins 56. The exhaust gas after the heat exchange in the fins 56 is discharged from the exhaust gas discharge pipe 58 on the bottom surface of the exhaust gas passage 40.

  On the other hand, the cathode air supplied from the cathode air supply pipe 60 into the cathode air passage 50 in S <b> 2 flows upward in the cathode air passage 50 while performing heat exchange with the fins 56. The cathode air is heated by heat exchange by the fins 56. The heated cathode air is supplied into the storage chamber 10 and used for heating the fuel cell 25.

  Next, the control device 100 monitors whether or not the reformer 26 has reached a predetermined temperature (S6). The predetermined temperature mentioned here refers to a temperature (about 100 ° C. in the present embodiment) that is less than a suitable operating temperature of the reformer. In the case of YES in S6, the control device 100 opens the regulating valve 48a and supplies water into the reformer 26 (S8). The water supplied into the reformer 26 is heated by an internal vaporization mechanism to become steam.

  Next, the control device 100 reduces the opening amounts of the adjusting valve 68a and the adjusting valve 70a to reduce the supply amount of fuel gas and air supplied to the burner 64 to a predetermined amount (for example, an amount of about 60 to 70%). (S10). As shown in FIG. 4, in the present embodiment, the control device 100 reduces the supply amount of the fuel gas for burner combustion from about 2.0 L / min to about 1.3 L / min, and reduces the supply amount of air to 30 L. Decrease from about / min to about 20 L / min. FIG. 4 is a graph showing the supply amount of fuel gas and air and the supply amount of cathode air to the burner 64 accompanying the operation at the time of starting the power generation device 2. As a result, the amount of heating per unit time of the burner 64 is reduced, and overheating of the reformer 26 is prevented.

  Next, the control device 100 reduces the opening degree of the regulating valve 60a to reduce the supply amount of the cathode air to a predetermined amount (for example, an amount of about 30%) as shown in FIG. 4 (S12). As shown in FIG. 4, in this embodiment, the control device 100 reduces the opening of the adjustment valve 60 a so that the supply amount of cathode air decreases from about 100 L / min to about 30 L / min in a few seconds. This facilitates ignition of off-gas which will be described later. In S10 described above, the supply amount of fuel gas and air already supplied to the burner 64 has been reduced to a predetermined amount. Therefore, the inside of the storage chamber 10 is depressurized by reducing the supply amount of cathode air in S12. Although there is a slight increase in the amount of fuel gas and air supplied, it is unlikely that the fuel gas will be supplied to the burner 64 significantly above the indicated value due to the reduced pressure (see FIG. 4). Therefore, misfire of the burner 64 can be prevented.

  Next, the control device 100 monitors whether or not the reformer 26 has reached a suitable operating temperature (400 ° C. or higher) (S14). If YES in S14, the control device 100 opens the adjustment valve 46a and supplies fuel gas to the reformer 26 (S16). In the reformer 26, a reforming reaction of a mixed gas of the fuel gas supplied in S16 and the water vapor generated in S8 is performed, and a suitable reformed gas mainly composed of carbon monoxide and hydrogen is obtained. Is generated (S18). The reformed gas generated in S18 is supplied into the reformed gas passage of each fuel cell 25 through the reformed gas supply pipe 28, the reformed gas chamber 30, the introduction pipe 32, and the manifold 34. At this point, the fuel cell 25 has not yet reached the operating temperature of 600 ° C., and therefore cannot sufficiently generate a power generation reaction. Therefore, the reformed gas supplied into the reformed gas passage at this time is discharged from the upper end of each fuel cell 25 as off-gas without being used for power generation. Since the air that has entered the reformed gas passage is driven out by the reformed gas, the fuel electrode is not oxidized by the surrounding oxygen even if the temperature of the fuel cell 25 rises to some extent.

  Next, the control device 100 operates the spark electrode in the vicinity of the upper end (off-gas combustion unit 27) of each fuel cell 25 to ignite off-gas and burn off-gas (S20). In addition, since the flow of the cathode air in the storage chamber 10 becomes gentle due to the decrease in the supply amount of the cathode air in S12, the off-gas is easily ignited in S20. When the off-gas combustion is started, the control device 100 increases the opening degree of the regulating valve 60a again to increase the supply amount of the cathode air supplied to the fuel cell 25 to a predetermined amount (S22). By increasing the supply amount of cathode air to a predetermined amount, combustion of off-gas is promoted. The combustion heat of the off gas is used for heating the reformer 26 together with the combustion heat of the burner 64. Further, the high-temperature exhaust gas generated by the combustion of the burner 64 and the off-gas combustion is heat-exchanged with the cathode air supplied to the fuel cell 25. The cathode air heated to a high temperature by the heat exchange is supplied to the fuel cell 25, whereby the fuel cell 25 is heated.

  Next, when the temperature of each fuel cell 25 reaches a suitable operating temperature (about 600 ° C. or higher) (S24), each fuel cell 25 uses the reformed gas supplied in the reformed gas passage to the surroundings. A power generation reaction is performed by reacting with the cathode air (S26). A high-temperature exhaust gas composed of water vapor and carbon dioxide is generated by the power generation reaction. Further, the off gas that has not been consumed for power generation is continuously burned in each off gas combustion unit 27. High-temperature exhaust gas generated by power generation reaction and off-gas combustion is used for heating the reformer 26. The high-temperature exhaust gas is heat-exchanged with the cathode air supplied to the fuel battery cell 25. The cathode air that has been heated to a high temperature by the heat exchange is supplied to the fuel cell 25 so that the fuel cell 25 is also continuously heated. By S24, both the reformer 26 and the fuel cell 25 are operated without falling below a suitable operating temperature. As a result, the power generation device 2 is thermally independent.

  The control device 100 stops the combustion of the burner 64 when both the reformer 26 and the fuel battery cell 25 are operated without falling below a suitable operating temperature (S28). When S28 ends, the series of operations of the power generation device 2 that accompanies startup ends. Thereafter, the power generation device 2 is continuously operated in a state where heat is self-supporting.

  Heretofore, the power generation apparatus according to the present embodiment has been described. In this embodiment, as shown in S10 and S12 of FIG. 3, the control device 100 reduces the supply amount of fuel gas and air supplied to the burner 64 (S10) and the cathode supplied to the fuel cell 25. The process (S12) for reducing the supply amount of air is not performed at the same time. That is, two processing procedures that cause decompression in the storage chamber 10 are executed at different timings. For this reason, in the power generation device 2 of the present embodiment, rapid pressure reduction in the storage chamber 10 is suppressed, and a situation in which fuel gas is supplied to the burner 64 significantly more than the indicated value is less likely to occur. Therefore, misfire of the burner 64 can be prevented. In the present embodiment, the control device 100 performs a process of reducing the supply amount of the cathode air supplied to the fuel cell 25 after the supply amounts of the fuel gas and the aerobic gas supplied to the burner 64 are reduced to a predetermined amount. Execute. By reducing the amount of fuel gas and air supplied to the burner 64 in advance, overheating of the reformer 26 can be prevented at an early stage.

(Second embodiment)
As shown in FIG. 5, when the supply amount of cathode air is decreased to a predetermined instruction value, the supply amount of cathode air may be decreased stepwise. As shown in FIG. 5, in this embodiment, the control device 100 divides the opening degree of the regulating valve 60 a into three times about every 10 seconds so that the opening degree corresponds to a predetermined instruction value. Make it smaller. According to this configuration, the internal pressure of the storage chamber 10 can be reduced stepwise as the cathode air supply amount decreases. Since rapid decompression in the storage chamber 10 can be suppressed, a situation in which fuel gas is supplied to the burner 64 much more than the indicated value is less likely to occur. The misfire of the burner 64 can be prevented more reliably.

(Other examples)
In each of the embodiments described above, the control device 100 reduces the cathode air supply amount to a predetermined instruction value after performing the process of reducing the supply amount of fuel gas and air supplied to the burner 64 (S10 in FIG. 3). Is executed (S12 in FIG. 3). Instead, the control device 100 executes a process (S12) for reducing the supply amount of the cathode air to a predetermined instruction value, and supplies the burner 64 to the burner 64 after the supply amount of the cathode air is reduced to the predetermined instruction value. The process (S10) which reduces the supply amount of the fuel gas and air to perform may be performed. In this case, off-gas ignition can be performed at an early stage by reducing the supply amount of the cathode air to a predetermined amount in advance. From an early stage, off-gas combustion heat can be used for continuous heating of the reformer 26.

Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above.
In addition, the technical elements described in the present specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings achieves a plurality of objects at the same time, and has technical utility by achieving one of the objects.

2 Power generator 4 Main body casing 10 Accommodating chamber 24 Cell stack 25 Fuel cell 26 Reformer 27 Off-gas combustion section 40 Exhaust gas passage 46 Fuel gas supply pipe 46a Adjustment valve 48 Water supply pipe 48a Adjustment valve 50 Cathode air passage 58 Exhaust gas exhaust pipe 60 Cathode air supply pipe 60a Adjustment valve 64 Burner 68 Combustion air supply pipe 68a Adjustment valve 70 Gas supply pipe 70a Adjustment valve

Claims (4)

A power generation device using a solid oxide fuel cell;
A reformer for reforming a mixed gas of fuel gas and water vapor into a reformed gas;
A solid oxide fuel cell that generates electricity by reacting the reformed gas with an aerobic gas; and
A combustion section that burns off-gas from the fuel cell and heats the reformer by the combustion heat;
A burner that burns fuel gas and heats the reformer with the combustion heat;
Equipped with a control device,
The control device is at least when starting the power generation device,
(1) Supplying fuel gas and aerobic gas to the burner to burn the fuel gas, and heating the reformer with the combustion heat;
(2) a processing procedure for supplying aerobic gas to the fuel cell;
(3a) After the processing procedures of (1) and (2), a processing procedure for reducing the amount of fuel gas and aerobic gas supplied to the burner;
(3b) After the processing procedures of (1) and (2), execute a processing procedure for reducing the supply amount of the aerobic gas supplied to the fuel cell,
The power generation apparatus characterized by executing the processing procedures (3a) and (3b) at different timings.   The power generation apparatus according to claim 1, wherein the processing procedure of (3b) is a processing procedure for gradually reducing the supply amount of the aerobic gas supplied to the fuel battery cell.   The control device executes the processing procedure of (3b) after the processing procedure of (3a) is executed and the supply amount of the fuel gas and the aerobic gas supplied to the burner is reduced to a predetermined amount. The power generator according to claim 1 or 2, wherein   The control device executes the processing procedure of (3a) after the processing procedure of (3b) is executed and after the supply amount of the aerobic gas supplied to the fuel cell is reduced to a predetermined amount. The power generator according to claim 1 or 2.

Images