JP2016062796A - Solid oxide type fuel cell system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a solid oxide type fuel cell system for stably operating power generation while suppressing staying of reformed water.SOLUTION: A solid oxide type fuel cell system comprises: a reformer 4 for perform steam reforming on a fuel gas; a cell stack 6 for generating power by oxidation and reduction of a reformed fuel gas and an oxidation material; a combustion zone 54 for combusting an excess fuel gas; an oxidation material preheater 52 for performing heat exchange between the oxidation material and a combustion exhaust gas; and a fuel cell housing 60 for accommodating the reformer 4, the cell stack 6, etc. First and second vaporizers 10, 12 for performing steam vaporization on reformed water are provided. The first vaporizer 10 is accommodated in the fuel cell housing 60; the second vaporizer 12 is disposed outside of the fuel cell housing 60. The second vaporizer 12 is disposed above the first vaporizer 10; a reformed water supply flow passage 18 extends from the second vaporizer 12 to the first vaporizer 10 vertically or with a downward gradient.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a solid oxide fuel cell system that generates power by oxidizing and reducing a fuel gas and an oxidant produced by reforming a hydrocarbon fuel gas.

 Conventionally, a fuel cell using a solid electrolyte as a membrane for conducting oxygen ions has been provided, a fuel electrode for oxidizing fuel gas is provided on one side, and an oxidizing material (for example, oxygen in the air) is provided on the other side. There is known a solid oxide fuel cell system provided with an oxidation electrode for reducing the oxygen. In this solid oxide fuel cell system, zirconia doped with yttria is generally used as the solid electrolyte, and hydrogen and monoxide in the reformed fuel gas obtained by reforming the fuel gas at a high temperature of 700 to 1000 ° C. Electricity is generated by electrochemical reaction of carbon, hydrocarbons and oxygen as an oxidizing material. Such a solid oxide fuel cell system has been developed as a promising power generation technology because it can generate power with particularly high power generation efficiency as compared with other fuel cell systems and gas engines.

  In such a solid oxide fuel cell system, a cell stack in which a plurality of fuel cells are stacked is used, and the reformed fuel gas that does not contribute to power generation of the cell stack because the operating temperature of the cell stack is high. Combustion heat obtained by burning (so-called surplus fuel gas) is directly applied to a vaporizer for vaporizing reformed water to obtain water vapor or a reformer for steam reforming the fuel gas. (For example, refer patent document 1).

  In this solid oxide fuel cell system, a combustion zone is arranged above the cell stack, and reformed fuel gas (excess fuel gas) that does not contribute to power generation is discharged from the combustion pole side of the cell stack to the combustion zone. It is burned in the combustion zone by the oxidant discharged from the oxygen electrode side. The vaporizer and the reformer are accommodated in the fuel cell housing together with the cell stack, and are disposed near the combustion zone in the fuel cell housing, for example, above the cell stack. Since steam generation in the vaporizer and steam reforming in the reformer are endothermic reactions, the combustion heat generated in this combustion zone is used for these steam generation and steam reforming. By using the combustion heat, it is possible to maintain the power generation reaction in the cell stack while maintaining a high operating temperature.

  In such a fuel cell system, fuel gas supply control and the like are performed in consideration of the fuel utilization rate. The fuel utilization rate is a ratio of how much generated current is taken out with respect to the supply rate of the valence electrons of the fuel gas, which is proportional to the flow rate of the fuel gas, and does not contribute to power generation as the fuel utilization rate increases. As the surplus fuel gas decreases, the power generation efficiency increases, and as the fuel utilization rate decreases, the surplus fuel gas that does not contribute to power generation increases and the power generation efficiency decreases. However, if the fuel utilization rate becomes too high, the heat of combustion due to the combustion of surplus fuel gas in the combustion zone is reduced, and the amount of heat for maintaining the inside of the fuel cell housing at a high temperature is insufficient, and conversely, the temperature decreases. Since the power generation performance of the cell stack is reduced, it is difficult to increase the fuel utilization rate beyond a certain value.

  Therefore, a solid oxide fuel cell system has been proposed that can maintain a high operating temperature and maintain high power generation efficiency even when the fuel utilization rate is increased (see, for example, Patent Document 2). In this solid oxide fuel cell system, first and second vaporizers for vaporizing reformed water are provided, and the reformed water is selectively supplied to the first and second vaporizers. Then, the steam vaporized in the first or second vaporizer is supplied to a reformer that performs steam reforming. The first carburetor is disposed in the fuel cell housing and is heated by combustion heat generated by combustion of surplus fuel gas in the combustion zone, and the second carburetor is disposed outside the fuel cell housing, It is heated by the combustion exhaust gas discharged out of the fuel cell housing from the combustion zone.

  In this solid oxide fuel cell system, the reforming water is supplied to the first vaporizer at the time of startup or the like, and the reforming water is vaporized by the first vaporizer using the combustion heat in the combustion zone. However, under normal operating conditions, the reforming water is supplied to the second vaporizer, and the heat of the combustion exhaust gas discharged from the combustion zone to the outside of the fuel cell housing is used to reform the water at the second vaporizer. Vaporization takes place. In this normal operation state, since the combustion heat in the combustion zone in the fuel cell housing is not used, the consumption of surplus fuel gas can be reduced by the amount of heat of vaporization in the second vaporizer, resulting in high While maintaining the fuel utilization rate, the fuel cell housing can be maintained at a high temperature to continue the power generation operation.

JP 2006-19084 A JP 2010-251309 A

  However, such a solid oxide fuel cell system has the following problems to be solved. First, in the second carburetor provided outside the fuel cell housing, compared with the first carburetor provided in the fuel cell housing, a high-temperature fluid (that is, combustion exhaust gas) that gives heat to the reforming water is used. If the temperature is low and thus the temperature is low, it is necessary to increase the heat transfer area required for heat exchange with the reforming water. When the heat transfer area is increased in this way, the amount of reforming water staying in the second vaporizer becomes larger than that in the first vaporizer, and the staying of such reforming water is caused by a bumping phenomenon (residence). If this bumping phenomenon occurs, the S / C (steam / carbon ratio) fluctuates abruptly and becomes one of the causes of the cell stack being damaged.

  Second, as the power output of the cell stack changes, the amount of surplus fuel gas discharged to the combustion zone in the fuel cell housing (that is, the amount of heat stored in the combustion exhaust gas) also fluctuates. The amount of reforming water staying in the vessel also changes over time. Such fluctuation of the accumulated water is larger in the operating state when the reforming water is supplied to the second vaporizer than in the operating state when the reforming water is supplied to the first vaporizer. Appears as a fluctuation with respect to the target value of S / C (steam / carbon ratio), which is the target of operation operation. When the temporal fluctuation of the staying water is moderate, no problem occurs. However, when the temporal fluctuation becomes steep, it becomes one of the causes of the cell stack being damaged. For example, when the S / C swings to the small side, the water vapor may decrease and carbon may be deposited, and when the S / C swings to the large side, the fuel gas may decrease and fuel shortage may occur. is there. Such time-dependent fluctuation of the staying water is more likely to occur in the second vaporizer where the reforming water is likely to stay than the first vaporizer, and the risk that the cell stack is damaged is also greater. .

  Third, since the reforming water is selectively supplied to the first and second vaporizers, two reforming water supply systems for supplying the reforming water are required, and the reforming water is also provided. A switching valve for switching the supply system is also required, and its structure and switching control become complicated, and its manufacturing cost also increases. Further, in connection with the switching control of the reforming water supply system, a discontinuous change in S / C is likely to occur before and after the switching.

  An object of the present invention is a solid oxide fuel cell system that can be operated with high power generation efficiency while maintaining a high fuel utilization rate, and that can be stably operated for power generation by suppressing retention of reforming water. Is to provide.

According to a first aspect of the present invention, there is provided a solid oxide fuel cell system comprising a reformer for reforming a hydrocarbon-based fuel gas and water vapor from reformed water, and reforming by the reformer. A cell stack including fuel cells that generate power by oxidizing and reducing the reformed fuel gas and the oxidant, a combustion zone for burning surplus fuel gas that does not contribute to power generation in the cell stack, and the cell stack An oxidizing material preheater for exchanging heat between the oxidizing material fed to the combustion exhaust gas discharged through the combustion zone, the reformer, the cell stack, and the oxidizing material preheater are accommodated A fuel cell housing comprising: a solid oxide fuel cell system comprising:
First and second vaporizers are provided for vaporizing the reformed water to generate water vapor. The first vaporizer is accommodated in the fuel cell housing and is burned by surplus fuel gas in the combustion zone. The second carburetor is disposed outside the fuel cell housing and heated by combustion exhaust gas discharged from the combustion zone through the oxidant preheater, and the reformed water is heated by the second carburetor. To the first vaporizer through the reforming water supply flow path,
The second vaporizer is disposed above the first vaporizer, and the reforming water supply passage extends from the second vaporizer to the first vaporizer with a vertical or downward gradient. It is characterized by.

  Further, in the solid oxide fuel cell system according to claim 2 of the present invention, the second carburetor defines a reforming water passage through which reforming water flows and an exhaust gas passage through which combustion exhaust gas flows. A reformer water inflow portion is provided at the upper end portion of the vaporizer body, a reforming water outflow portion is provided at the lower end portion thereof, and the reforming water outflow portion is the reforming water supply flow path. The reforming water flow path extends from the reforming water inflow portion to the reforming water outflow portion with a vertical or downward gradient.

  In the solid oxide fuel cell system according to claim 3 of the present invention, the oxidizing material preheater and the exhaust gas passage of the second vaporizer are connected via an exhaust gas supply passage. A combustion catalyst is disposed in the exhaust gas supply channel and / or the exhaust gas channel of the second carburetor.

  In the solid oxide fuel cell system according to claim 4 of the present invention, at least one of the second carburetor, the reforming water supply flow path, and the combustion catalyst may be used. Preheating heating means for heating one is provided.

  Further, in the solid oxide fuel cell system according to claim 5 of the present invention, temperature detecting means is provided at least at one of the second vaporizer, the reforming water supply passage, and the exhaust gas supply passage. And at least one supply flow rate of hydrocarbon fuel gas, reforming water and air and / or power generation output of the cell stack is controlled based on the temperature detected by the temperature detecting means. To do.

  Further, in the solid oxide fuel cell system according to claim 6 of the present invention, a temperature detection means is provided in at least one place of the second vaporizer, the reforming water supply flow path, and the exhaust gas supply flow path. It is arranged to control to increase the fuel utilization rate in the system when the temperature detected by the temperature detecting means rapidly decreases in a steady operation state at a high fuel utilization rate.

  Further, in the solid oxide fuel cell system according to claim 7 of the present invention, temperature detecting means is provided at least at one of the second vaporizer, the reforming water supply passage, and the exhaust gas supply passage. Is provided, and the heating amount of the preheating heating means is controlled based on the temperature detected by the temperature detecting means.

  Furthermore, in the solid oxide fuel cell system according to claim 8 of the present invention, a fuel gas supply channel for supplying hydrocarbon fuel gas is connected to the first or second vaporizer, and carbonized. The hydrogen-based fuel gas is mixed with water vapor generated in the first or second vaporizer.

 According to the solid oxide fuel cell system of the first aspect of the present invention, the first carburetor is accommodated in the fuel cell housing, heated by the combustion of excess fuel gas in the combustion zone, and the second vaporization. The regenerator is disposed outside the fuel cell housing and is heated by the combustion exhaust gas discharged from the combustion zone through the oxidant preheater, and the reforming water is supplied from the second vaporizer through the reforming water supply passage. Since it is fed to the vaporizer, the reformed water fed to the reformer is first vaporized in the second vaporizer heated by the heat of the combustion exhaust gas discharged outside the fuel cell housing, Thereafter, it is vaporized by a first vaporizer heated by combustion of surplus fuel gas in the combustion zone in the fuel cell housing. Therefore, the heat of the combustion exhaust gas discharged out of the fuel cell housing is also used for vaporization of the reforming water. Therefore, the consumption of surplus fuel gas is reduced by the amount of heat of vaporization in the second vaporizer. As a result, the system can be operated with high power generation efficiency while maintaining a high fuel utilization rate.

  Further, the second vaporizer is disposed above the first vaporizer, and the reforming water supply flow path extends from the second vaporizer to the first vaporizer with a vertical or downward gradient. When the reformed water flows from the second vaporizer to the reformed water feed channel, the reformed water flows down to the first vaporizer through the reformed water feed channel, and in this first vaporizer The surplus fuel gas in the combustion zone is vaporized by the heat of the fuel and fed to the reformer. Accordingly, the retention of reforming water in the reforming water supply flow path can be reduced, thereby suppressing fluctuations in S / C (steam / carbon ratio) and stably supplying steam to the reformer. Can be paid.

  Further, the second vaporizer is disposed above the first vaporizer, and the reformed water is fed from the second vaporizer through the reformed water feed channel to the first vaporizer. The quality water supply system is a single system and does not require a switching valve or the like, so that the configuration relating to the reformed water supply system can be simplified and the production cost can be reduced.

  In the solid oxide fuel cell system according to claim 2 of the present invention, the reforming water flow path of the second vaporizer extends from the reforming water inflow portion at the upper end portion of the vaporizer body to the lower end portion thereof. Since it extends vertically or downwardly to the reforming water outflow portion, the reforming water that has flowed in from the reforming water inflow portion flows down through the reforming water flow path to reduce the retention of the reforming water in the second vaporizer. As a result, fluctuations in S / C (steam / carbon ratio) can be further suppressed.

  In the solid oxide fuel cell system according to claim 3 of the present invention, the oxidant preheater and the exhaust gas passage of the second vaporizer are connected via the exhaust gas supply passage, Since the combustion catalyst is disposed in the exhaust gas supply flow path and / or the exhaust gas flow path of the second carburetor, the unburned gas contained in the combustion exhaust gas is burned by the combustion catalyst. The combustion heat of the unburned gas can be used for vaporizing the reforming water in the second vaporizer.

  In the solid oxide fuel cell system according to claim 4 of the present invention, the preheating heating means is provided in association with at least one of the second carburetor, the reforming water supply passage and the combustion catalyst. Therefore, in the second vaporizer, the reformed water flowing through the second vaporizer can be heated, and in the reformed water feed channel, the reformed water feed channel is provided. The reforming water flowing down can be heated, and in the case of a combustion catalyst, the combustion catalyst can be heated to activate the combustion catalyst to promote the combustion of unburned gas.

  In the solid oxide fuel cell according to claim 5 of the present invention, the temperature detecting means is arranged at least in one place of the second vaporizer, the reforming water feed channel and the exhaust gas feed channel. And at least one supply flow rate of hydrocarbon fuel gas, reforming water and air (and / or power generation output of the cell stack) is controlled based on the temperature detected by the temperature detecting means. The temperature associated with the reformed water flowing through the second vaporizer, the temperature associated with the reformed water flowing down the reformed water supply channel for the reformed water supply channel, and the exhaust gas. In the gas feed channel, based on the temperature associated with the combustion exhaust gas flowing through the exhaust gas feed channel, at least one of hydrocarbon fuel gas, reforming water and air (and / or cell stack) Power generation output) is controlled as required to stabilize the fuel cell system and generate power Rukoto can.

  According to the solid oxide fuel cell system of the sixth aspect of the present invention, the second carburetor (reformed water supply flow path, exhaust gas supply flow) in a steady operation state at a high fuel utilization rate. When the temperature detected by the temperature detecting means disposed on the road or the like suddenly decreases and a tendency to decrease the vaporization capacity of the second vaporizer is estimated, the fuel utilization rate in the system is reduced. Control and increase the surplus fuel gas to increase the amount of combustion heat, thereby recovering the vaporization capacity of the second vaporizer, so that the vaporization capacity of the second vaporizer can be maintained and stabilized. Power generation operation.

  In the solid oxide fuel cell system according to claim 7 of the present invention, the temperature detecting means is provided in at least one place of the second vaporizer, the reforming water supply passage and the exhaust gas supply passage. Since the heating amount of the preheating heating unit is controlled based on the temperature detected by the temperature detection unit, in the second vaporizer, the temperature related to the reforming water flowing through the second vaporizer, the reforming The temperature related to the reformed water flowing down the reformed water feed channel in the case of the water feed channel, and the combustion exhaust gas flowing in the exhaust gas feed channel in the case of the exhaust gas feed channel. Based on the relevant temperature, the heating amount of the preheating heating means can be controlled and heated as desired.

  Furthermore, according to the solid oxide fuel cell system according to claim 8 of the present invention, the fuel gas supply flow path for supplying hydrocarbon fuel gas is connected to the first or second vaporizer. . When connected to the first vaporizer, the fuel gas from the fuel gas supply flow path is supplied to the first vaporizer, and the first vaporizer generates water vapor (generated by the second vaporizer and supplied to the first vaporizer. The water vapor fed and the water vapor generated in the first vaporizer) are mixed. Further, when connected to the second vaporizer, the fuel gas from the fuel gas supply flow path is supplied to the second vaporizer and mixed with water vapor (water vapor generated by the second vaporizer) in the second vaporizer. Then, the mixed fuel gas and water vapor are fed to the first vaporizer through the reforming water feed flow path and further mixed with the water vapor generated in the first vaporizer.

1 is a simplified diagram showing a first embodiment of a solid oxide fuel cell system according to the present invention. Sectional drawing which shows simply the 2nd vaporizer | carburetor of the solid oxide fuel cell system of FIG. 3A is a cross-sectional view showing a first modification of the second vaporizer, FIG. 3B is a cross-sectional view showing a second modification of the second vaporizer, and FIG. Sectional drawing which shows the 3rd modification of 2 vaporizers. FIG. 4 is a simplified diagram showing a part of a second embodiment of a solid oxide fuel cell system according to the present invention. Sectional drawing which shows other modification of a 2nd vaporizer | carburetor. FIG. 4 is a simplified diagram showing a part of a third embodiment of a solid oxide fuel cell system according to the present invention.

 Hereinafter, various embodiments of a solid oxide fuel cell system according to the present invention will be described with reference to the accompanying drawings.

<First Embodiment>
First, with reference to FIG.1 and FIG.2, the solid oxide fuel cell system of 1st Embodiment is demonstrated. In FIG. 1, the illustrated solid oxide fuel cell system 2 performs power generation by consuming, for example, a hydrocarbon-based fuel gas mainly composed of methane as a fuel gas, for example, natural gas (city gas). Reformer 4 for reforming hydrocarbon fuel gas to produce reformed fuel gas, reformed fuel gas produced by reformer 4 and air as an oxidant (included in air) A solid oxide cell stack 6 that generates electric power by oxidation and reduction of (oxygen). In the following description, hydrocarbon fuel gas as fuel gas may be referred to as “raw fuel gas”.

   The cell stack 6 has a plurality of solid oxide fuel cells for generating power by a fuel cell reaction, and is configured by stacking these fuel cells via a current collecting member. Although not shown, the fuel cell includes a solid electrolyte that conducts oxygen ions, a fuel electrode provided on one side of the solid electrolyte, and an oxygen electrode provided on the other side of the solid electrolyte, As the electrolyte, for example, zirconia doped with yttria is used.

  In this solid oxide fuel cell system 2, two vaporizers are used as vaporizers for vaporizing water (which may be referred to as “reforming water” in the following description) and supplying it to the reformer 4. A first vaporizer 10 and a second vaporizer 12 are provided, and a second vaporizer 12 is disposed upstream of the first vaporizer 10. The fuel electrode introduction side of the cell stack 6 is connected to the reformer 4 via a reformed fuel gas feed channel 14, and the reformer 4 is connected to the first via a gas / steam feed channel 16. The first vaporizer 10 is connected to the first vaporizer 10, and the first vaporizer 10 is connected to the second vaporizer 12 via the reforming water supply passage 18.

  The second vaporizer 12 is connected to reforming water supply means 20 for supplying reforming water. In the illustrated form, the reforming water supply means 20 includes a water supply source 22 such as a water tank and a reforming water supply passage 24 that supplies the reforming water from the water supply source 22 to the second vaporizer 12. A water supply pump 26 is disposed in the reformed water supply channel 24. With this configuration, when the water supply pump 26 operates, the reformed water from the water supply source 22 is supplied to the second vaporizer 12 through the reformed water supply channel 24.

  The first vaporizer 10 is connected to a fuel gas supply means 28 for supplying fuel gas. The illustrated fuel gas supply means 28 includes a fuel gas supply source 30 for supplying the raw fuel gas and a fuel gas supply flow path 32 for supplying the raw fuel gas to the first carburetor 10. A desulfurizer 34, a gas supply pump 36, and a flow rate sensor 38 are disposed in the path 32. The desulfurizer 34 removes sulfur components contained in the raw fuel gas, and the gas supply pump 36 sends the raw fuel gas from the fuel gas supply source 30 to the first carburetor 10 through the fuel gas supply flow path 32. The flow rate sensor 38 measures the flow rate of the raw fuel gas supplied through the fuel gas supply channel 32. The fuel gas supply channel 32 is further provided with on-off valves 40 and 42. Two on-off valves 40 and 42 open and close the fuel gas supply passage 32 to supply and stop the supply of fuel gas. With this configuration, when the gas supply pump 36 is operated while the on-off valves 40 and 42 are open, the fuel gas from the fuel gas supply source 30 is supplied to the first carburetor 10 through the fuel gas supply flow path 32. Is done.

  In the reformer 4, for example, alumina having ruthenium supported thereon is used as a reforming catalyst, and the reforming catalyst steam reforms the fuel gas as described later. In this embodiment, the second vaporizer 12 vaporizes the water supplied through the reformed water supply flow path 24 to generate water vapor, and the first vaporizer 10 receives the reformed water from the second vaporizer 12. The reformed water fed through the feed channel 18 is vaporized to generate steam, and the steam (steam generated by the second vaporizer 12 and fed through the reformed water feed channel 18). And the water vapor generated in the first vaporizer 10) and the fuel gas supplied through the fuel supply passage 32 are mixed.

  In this embodiment, the reformer 4 and the first vaporizer 10 are configured separately, but the reformer 4 and the first vaporizer 10 may be configured integrally. Further, although the fuel gas supply flow path 32 is connected to the first vaporizer 10, the fuel gas supply flow path 32 may be connected to the second vaporizer 12 instead of such a configuration. Alternatively, the raw fuel gas from the fuel gas supply source 30 may be directly connected to the reformer 4 by being connected to the reformer 4.

  An oxidant supply means 44 for supplying air as an oxidant is connected to the introduction side of the oxygen electrode of the cell stack 6. The oxidant supply means 44 shown in the figure is an oxidant supply source 46 for supplying air (that is, oxygen in the air) as an oxidant (in the case of the embodiment, ambient ambient air is an oxidant supply source). The oxidizing material supply channel 48 supplies the oxidizing material from the oxidizing material supply source 46 to the oxygen electrode side of the cell stack 6, and the blower 50 and the oxidizing material heater 52 are arranged in the oxidizing material supply channel 48. It is installed. The oxidant preheater 52 is composed of, for example, an oxidant preheater heat exchanger, and uses an exhaust gas to oxidize the supply channel 48 (that is, the air channel 53 of the oxidant preheater 52) as will be described later. Heat the air flowing through. With this configuration, when the blower blower 50 operates, the surrounding air is supplied to the fuel electrode side of the cell stack 6 through the oxidant supply passage 48, and the supplied air is supplied to the oxidant reheater 52. Heated.

  Combustion zones 54 are provided on the discharge side of the fuel electrode and oxygen electrode of the cell stack 6, and surplus fuel gas discharged from the fuel electrode side of the cell stack 6 and air (oxygen) discharged from the oxygen electrode side thereof. Are contained in the combustion zone 54 and burned. The combustion chamber 54 is connected to an exhaust gas supply passage 56, and an oxidant preheater 52 (the combustion exhaust gas passage 55) is disposed in the exhaust gas supply passage 56. 56 is connected to the second vaporizer 12. Since it is configured in this way, the combustion exhaust gas from the combustion zone 54 is supplied to the second vaporizer 12 through the exhaust gas supply passage 56 and the oxidant preheater 52, and is thus supplied. In the oxidant preheater 52, heat exchange is performed between the combustion exhaust gas flowing through the combustion exhaust gas passage 55 and the air (oxidant) flowing through the air passage 53, and the air heated by this heat exchange is The combustion exhaust gas supplied to the cell stack 6 and lowered in temperature by heat exchange is discharged into the atmosphere through the second vaporizer 12 and the exhaust gas discharge passage 58.

  In this embodiment, the reformer 4, the cell stack 6, the first carburetor 10 and the air preheater 52 are accommodated in the fuel cell housing 60, and the reformer 4 and the first carburetor 10 are in the vicinity of the combustion zone 54, For example, it is disposed above it. The inner wall surface of the fuel cell housing 60 is covered with a heat insulating material (not shown) to define the high temperature chamber 62, and the reformer 4, the cell stack 6, the first vaporizer 10, and the air preheater 52 are included in the high temperature chamber 62. At high temperature. The second vaporizer 12 is disposed outside the fuel cell housing 60. With this configuration, the reformer 4 and the first vaporizer 10 are heated by the combustion of excess fuel gas in the combustion zone 54, and the reformed water in the first vaporizer 10 is utilized using this combustion heat. The vaporization is performed, and the water vaporization in the second vaporizer 12 uses the exhaust heat of the combustion exhaust gas exhausted through the exhaust gas supply passage 56 and the heat in the fuel cell housing 60 is used. There is no.

  In this embodiment, a controller 64 for controlling the operation of various devices (for example, the water supply pump 26, the gas supply pump 36, the blower blower 50, etc.) of the solid oxide fuel cell system 2 is provided, and the flow rate sensor 38 is provided. Is sent to the controller 64. The controller 64 controls the operation of the various devices described above and also controls the operation of the two on-off valves 40 and 42.

  An outline of the power generation operation of the solid oxide fuel cell system 2 is as follows. When the solid oxide fuel cell system 2 is activated, the blower blower 50 is activated, and air from the water supply means 44 is supplied to the oxygen electrode side of the cell stack 6 through the oxidant reheater 52, and the blower blower 50 rotates. By controlling the number, the amount of air supply is controlled. Further, the on-off valves 40 and 42 are opened, the gas supply pump 36 is operated, and the fuel gas (raw fuel gas) from the fuel gas supply means 28 passes through the desulfurizer 34, the first vaporizer 10 and the reformer 4. The amount of fuel gas supplied is controlled by controlling the rotational speed of the gas supply pump 36 supplied to the fuel electrode side of the cell stack 6. Further, an ignition device (not shown) disposed in the combustion zone 54 is ignited, and fuel gas is burned in the combustion zone 54 in this way.

  When the temperature of the first carburetor 10 rises (for example, rises to about 200 ° C.) by the combustion heat of the fuel gas in the combustion zone 54, the water supply pump 26 is activated and the reforming from the reforming water supply means 20 is performed. The quality water is supplied to the first vaporizer 10 through the second vaporizer 12, and the supply amount of the reforming water is controlled by controlling the rotation speed of the water supply pump 26. At this time, the combustion exhaust gas from the combustion zone 54 is discharged to the outside through the exhaust gas supply passage 56 and the second carburetor 12, so that the reformed water supplied to the second carburetor 12 is the combustion exhaust gas. A part of the gas is vaporized by using the heat of the gas to be steam, and the reformed water containing the steam is fed to the first vaporizer 10 through the reformed water feed channel 18. Further, since the first vaporizer 10 is heated by the surplus fuel gas in the combustion zone 54, the reformed water fed in this way is vaporized in the first vaporizer 10 by using this combustion heat, and the water vapor In this first vaporizer 10, water vapor and fuel gas are mixed, and mixed fuel gas (fuel gas in which fuel gas and water vapor are mixed) is supplied to the reformer 4 through the gas / water vapor supply passage 16. Is done. The reformed water from the reformed water supply means 20 becomes water vapor while flowing through the second vaporizer 12 and the first vaporizer 10 in this way.

  In the reformer 4, a steam reforming reaction is performed between the raw fuel gas and the steam, and the reformed fuel gas (reformed fuel gas) passes through the reformed fuel gas supply flow path 14 and serves as a fuel for the cell stack 6. It is fed to the pole side. Further, the air from the oxidant feeding means 44 is supplied to the oxidant preheater 52 through the oxidant feed channel 48, and is discharged from the combustion zone 54 in the oxidant preheater 52 to be exhaust gas feed channel 56. Heat exchanged with the combustion exhaust gas flowing through the air, and the air heated by the heat exchange is sent to the oxygen electrode side of the cell stack 6.

  In this way, when the temperature of the cell stack 6 reaches the operating temperature (for example, the cell stack 6 reaches about 650 ° C.), the power generation operation of the solid oxide fuel cell system 2 is performed. In this power generation operation, the reformed fuel gas is oxidized on the fuel electrode side of the cell stack 6, the oxygen in the air is reduced on the oxygen electrode side, and the oxidation on the fuel electrode side and the reduction on the oxygen electrode side are performed. Electricity is generated by an electrochemical reaction. The fuel gas discharged from the fuel electrode side of the cell stack 6 is burned using oxygen in the air (combustion air) discharged from the oxygen electrode side, and is modified using the combustion heat of this surplus fuel gas. The mass device 4 and the first vaporizer 10 are heated as described above.

  The combustion exhaust gas generated by the combustion in the combustion zone 54 is supplied to the oxidant preheater 52 through the exhaust gas supply passage 56, and the air supplied from the oxidant supply means 44 in the oxidant preheater 52 Then, after the reforming water supplied from the reforming water supply means 20 is heated in the second vaporizer 12, it is discharged to the atmosphere through the exhaust gas discharge channel 58.

  In this embodiment, the first carburetor 10 is disposed in the fuel cell housing 60 and the second carburetor 12 is disposed outside the fuel cell housing 60. It is configured. The second vaporizer 12 is configured as shown in FIG. In FIG. 2, the second carburetor 12 includes a carburetor body 74 that defines a reforming water passage 70 through which reforming water flows and an exhaust gas passage 72 through which combustion exhaust gas flows. The reforming water flow path 70 includes an upper water space portion 76 provided at the upper end portion in the vaporizer main body 72, a sewage space portion 78 provided at the lower end portion thereof, an upper water space portion 76, and a sewage space portion 78. And a plurality of intermediate water spaces 80 communicating with each other. The upper water space portion 76 of the reformed water channel 70 is partitioned by an upper partition plate 82, the sewage space portion 78 is partitioned by a lower partition plate 84, and the intermediate water space portion 80 includes the upper water space portion 76 and the sewage water. It is comprised from the tubular member 86 which connects between the space parts 78, and the some tubular member 86 is extended in the perpendicular downward direction. Further, the reforming water inflow portion 90 is provided at the upper end portion (in this embodiment, the upper end wall 88) of the vaporizer body 74, and the reforming water outflow portion 94 is provided at the lower end portion (in this embodiment, the lower end wall 92). ing.

  The exhaust gas flow path 72 is disposed between the upper water space 76 and the sewage space 78 of the reformed water flow path 70 (in other words, between the upper partition plate 82 and the lower partition plate 84). They are partitioned by an intermediate partition plate 96 arranged in a staggered pattern at intervals in the direction. An exhaust gas inflow portion 100 is provided at a lower end portion (upper portion of the sewage space portion 78) of the peripheral side wall 98 of the vaporizer main body 74, and an upper end portion (lower portion of the upper water space portion 76) is provided at the upper end portion thereof. An exhaust gas outlet 102 is provided.

  Since it is configured in this way, the reforming water supplied through the reforming water supply channel 24 flows into the reforming water channel 70 of the vaporizer body 74 from the reforming water inflow portion 90, and enters the upper water space portion. 2, after flowing downward into the sewage space 78 through the plurality of intermediate water spaces 80 as shown by broken line arrows in FIG. 10 is sent. On the other hand, the combustion exhaust gas flowing through the exhaust gas supply passage 56 flows into the exhaust gas passage 72 of the carburetor main body 74 from the exhaust gas inflow portion 100, and the inside of the exhaust gas passage 72 is indicated by a solid arrow in FIG. As shown, after flowing upward in a staggered pattern, the exhaust gas is discharged from the exhaust gas outlet 102 to the atmosphere through the exhaust gas discharge passage 58. Then, heat exchange is performed between the reformed water flowing in the reformed water flow path 70 and the combustion exhaust gas flowing in the exhaust gas flow path 72, and the reformed water is heated by the heat of the combustion exhaust gas (so-called waste heat). Is heated to produce water vapor. For example, when the calorific value of the combustion exhaust gas is small, part of the reformed water is vaporized and steam is generated, and when the calorific value is large, most or all of the reformed water is vaporized and steam is generated.

  In relation to the second vaporizer 12, the following configuration is desirable. A reforming water supply passage 18 that communicates the second vaporizer 12 (specifically, the reformed water outflow portion 94) and the first vaporizer 10 (specifically, the inflow portion thereof), It is desirable to extend downward along the entire length with a vertical or downward gradient. With this configuration, the reformed water that has flowed through the second vaporizer 12 flows downward toward the first vaporizer 10 and is improved. It is fed to the first vaporizer 10 without staying in the quality water feed channel 18. Therefore, the reformed water from the second vaporizer 12 is fed to the first vaporizer 10 little by little, and the reformed water is vaporized little by little in the first vaporizer 10, thereby becoming temporary. It is possible to prevent a large amount of water vapor from being generated and fed to the downstream side, and to prevent the S / C (steam / carbon ratio) from fluctuating greatly.

  Further, in the second vaporizer 12, the reforming water flow path 70 extends downward from the reforming water inflow portion 90 to the reforming water outflow portion 92 vertically (see FIG. 2) or downwardly. By configuring in this way, the reforming water supplied to the second vaporizer 12 flows downward in the reforming water flow path 70 toward the reforming water outflow portion 94, and the reforming water flow It flows in the reforming water supply flow path 18 without staying in the path 94. Therefore, in the second vaporizer 12, the reformed water flows downward little by little and is vaporized, whereby a large amount of the reformed water is temporarily supplied to the reformed water supply passage 18. It is possible to prevent the S / C from fluctuating greatly.

  This solid oxide fuel cell system has the following features in relation to the above-described configuration. In the steady power generation state of the cell stack 6, the temperature of the combustion exhaust gas flowing from the combustion zone 54 through the exhaust gas supply passage 56 is high. In such a case, as described above, the heat exchange in the second vaporizer 12 The reforming water supplied through the reforming water supply flow path 24 is mostly or entirely vaporized into water vapor while flowing through the reforming water flow path 70 of the second vaporizer 12, and thus generated. Steam (which may contain a small amount of reforming water) is fed to the first vaporizer 10. In such a case, the first vaporizer 10 hardly evaporates the reforming water. In such a case, there is no problem even if the generation of combustion heat due to the combustion of the surplus fuel gas in the combustion zone 54 is suppressed to a low level. Considering the consumption of fuel gas, it is possible to control the fuel utilization rate to be increased. For example, the fuel utilization rate of the system can be increased by about 5 to 10 points from about 70% to about 75 to 80%, for example. It is possible to increase the power generation efficiency while maintaining the operating temperature of the cell stack 6 at a high temperature by performing the control for increasing the fuel utilization rate in this way by the controller 64.

  As the second vaporizer, for example, one having the configuration shown in FIG. 3 may be used. In the second vaporizer 12A of the first modification shown in FIG. 3A, the vaporizer body 74A includes a cylindrical outer cylindrical member 112 having a large outer diameter, and a radially inner side of the outer cylindrical member 112. The inner cylindrical member 114 (for example, a tubular member) having a small outer diameter disposed in the inner cylindrical member 114 is provided with a reforming water flow path 70A defined inside the inner cylindrical member 114. An annular exhaust gas passage 72 </ b> A is defined between the outer cylindrical member 112.

  One end portion (upper end portion) of the inner cylindrical member 114 is connected to the reforming water supply channel 24 (see FIG. 1) and functions as a reforming water inflow portion 0A into which the reforming water flows, and the other end portion. The (lower end) is connected to the reforming water supply flow path 18 (see FIG. 1) and functions as a reforming water outflow portion 94A through which the reforming water flows out. Further, an exhaust gas inflow portion 100A is provided at the lower end portion of the outer cylindrical member 112, and the exhaust gas inflow portion 100A is connected to the exhaust gas supply passage 56 (see FIG. 1), and an exhaust gas is provided at the upper end portion thereof. A gas outflow portion 102A is provided, and the exhaust gas outflow portion 02A is connected to the exhaust gas discharge passage 58 (see FIG. 1).

  Also in the second vaporizer 12A, the reforming water channel 70A extends vertically downward from the reforming water inflow portion 90A to the reforming water outflow portion 94A, and the reforming water flowing in from the reforming water inflow portion 90A is After flowing downward in the reforming water flow path 70A as indicated by a broken line arrow in FIG. 3 (a), it is fed from the reforming water outflow portion 94A to the reforming water feed flow path 18 (see FIG. 1). . Further, the exhaust gas flow path 72A extends upward around the outer periphery of the reforming water flow path 70A, and the combustion exhaust gas flowing in from the exhaust gas inflow portion 100A flows into the exhaust gas flow as shown by solid line arrows in FIG. After flowing upward in the passage 72A, the exhaust gas is discharged from the exhaust gas outflow portion 102A to the exhaust gas discharge passage 58 (see FIG. 1).

  Even when such a second vaporizer 12A is used, heat exchange is performed between the reformed water flowing through the reformed water flow path 70A and the combustion exhaust gas flowing through the exhaust gas flow path 72A. Similar to the second vaporizer 12 shown, the heat of the combustion exhaust gas can be used to vaporize the reformed water to generate water vapor, and to prevent the reformed water from staying in the reformed water flow path 70A. be able to.

  Moreover, in the 2nd vaporizer 12B of the 2nd deformation | transformation form shown in FIG.3 (b), the vaporizer main body 74B has the cylindrical outer cylindrical member 112B with a large outer diameter, and the diameter of this outer cylindrical member 112B. A cylindrical inner cylindrical member 114B having a small outer diameter disposed on the inner side in the direction, and similarly to the first modified embodiment, a reforming water flow path 70B is defined inside the inner cylindrical member 114B, and the inner cylinder An annular exhaust gas passage 72B is defined between the cylindrical member 114B and the outer cylindrical member 112B, and a number of heat transfer promoting members 122 are disposed in the reforming water passage 70B. The heat transfer promoting member 122 can be formed of, for example, a ball-shaped member made of a ceramic material or a metal material (for example, stainless steel), and is heated by the combustion exhaust gas flowing through the exhaust gas flow path 72B, and the reformed water flow path It promotes heat transfer to the reformed water flowing in 70B.

  One end portion (upper end wall) of the inner cylindrical member 114B is provided with a reforming water inflow portion 90B that extends upward through the upper end wall 124 of the outer cylindrical member 112B, and the other end portion (lower end wall). Is provided with a reforming water outflow portion 94B that extends downward through the lower end wall 126 of the outer cylindrical member 112B. Similarly to the first modification, an exhaust gas inflow portion 100B is provided at the lower end portion of the outer cylindrical member 112B, and an exhaust gas outflow portion 102B is provided at the upper end portion thereof.

  Also in the second vaporizer 12B, the reforming water flow path 70B extends vertically downward from the reforming water inflow portion 90B to the reforming water outflow portion 94B. The water flows downward in the reformed water flow path 70B as indicated by the broken arrow in FIG. 3B, and the exhaust gas flow path 72B extends upward in the outer periphery of the reformed water flow path 70B. The combustion exhaust gas flowing in from the exhaust gas inflow portion 100B flows upward in the exhaust gas flow path 72B as shown by the solid line arrow in FIG. 3B, and the first modification described above also in this second modification. The effect similar to a form can be achieved. In addition, since a large number of heat transfer promotion members 122 are filled in the reforming water flow path 70B, the heat of the heat transfer promotion member 122 heated by the combustion exhaust gas is used to promote the vaporization of the reforming water. Water vapor can be generated.

  Further, in the second vaporizer 12C of the third modification shown in FIG. 3C, the vaporizer body 74C includes a cylindrical outer cylindrical member 112C having a large outer diameter, and a diameter of the outer cylindrical member 112C. A tubular member 114C disposed on the inner side in the direction, and the tubular member 114C is disposed in a spirally downward gradient in the outer tubular member 112C, and the helical reformed water flow path is disposed inside the tubular member 114C. 70C is defined, and an exhaust gas flow path 72C is defined between the tubular member 114C and the outer cylindrical member 112C.

  One end (upper end) of the tubular member 114C extends upward through the upper end wall 124C of the outer cylindrical member 112C, and the one end functions as the reforming water inflow portion 90C. The other end (lower end) extends downward through the lower end wall 126C of the outer cylindrical member 112C, and the other end functions as the reforming water outflow portion 94C. Similarly to the first modification, an exhaust gas inflow portion 100C is provided at the lower end portion of the outer cylindrical member 112C, and an exhaust gas outflow portion 102C is provided at the upper end portion thereof.

  In the second vaporizer 12C, the reforming water flow path 70C extends downwardly from the reforming water inflow portion 90C to the reforming water outflow portion 94C. As shown by the broken line arrow in FIG. 3C, the quality water flows spirally downward without staying in the reforming water flow path 70C, and the exhaust gas flow path 72C surrounds the reforming water flow path 70C. Therefore, the combustion exhaust gas flowing in from the exhaust gas inflow portion 100C flows upward in the exhaust gas passage 72C as shown by the solid line arrow in FIG. As described above, the same effect as that of the first modified embodiment described above can also be achieved by setting the reforming water channel 70C to have a downward slope. In addition, since the reforming water flow path 70C extends in a spiral shape, the contact area between the combustion exhaust gas flowing in the exhaust gas flow path 72C and the reforming water flow path 70C can be increased. It is possible to increase the efficiency of water vaporization of the reformed water by increasing the heat recovery of the water. The reforming water flow path 70C may be configured to extend linearly with a downward slope instead of being configured in a spiral shape, and has an angle enough to allow the reforming water to flow down without stagnation. It is desirable to have a downward slope.

  In the second carburetor 12 of the first embodiment (the carburetors 12A to 12C of the first to third modifications), the exhaust gas inflow portion 100 (100A to 100A to the lower end portion of the outer cylindrical member 112 (112A to 112C). 100C), an exhaust gas outflow portion 102 (102A to 102C) is provided at the upper end thereof, and directed from the second vaporizer 12 (12A to 12C) toward the first vaporizer 10, that is, in the flow direction of the reforming water. The combustion exhaust gas is made to flow so that the temperature becomes an upward slope toward the downstream side as viewed, but on the contrary, the exhaust gas inflow portion 100 (at the upper end portion of the outer cylindrical member 112 (112A to 112C) 100A to 100C), and an exhaust gas outflow portion 102 (102A to 102C) may be provided at the lower end thereof. In such a configuration, drainage of condensed water due to condensation of moisture in the combustion exhaust gas is performed. Easy line It becomes possible.

  Further, as shown by a one-dot chain line in FIG. 1, a portion exposed to the outside (that is, the second vaporizer 12 and the fuel) in the reformed water supply passage 18 (for example, composed of a reforming water pipe). It is desirable to cover the portion between the battery housing 60 and the heat insulating material 132. In addition, a portion exposed to the outside (that is, a portion located between the fuel cell housing 60 and the second carburetor 12) in the exhaust gas supply passage 56 (for example, configured from an exhaust gas pipe) is also provided. It is desirable to cover with the heat insulating material 134, and by covering with the heat insulating materials 132 and 134 in this way, heat dissipation loss to the outside can be suppressed. The reformed water supply passage 18 and the exhaust gas supply passage 56 do not need to be individually covered with the heat insulating materials 132 and 134, and they may be collectively covered with the heat insulating material. The externally exposed portions (the externally exposed piping portions) of the water supply passage 18 and the exhaust gas supply passage 56 are configured to be extremely short and insulated by using a heat insulating material (not shown) on the fuel cell housing 60 side. You may make it do.

<Second Embodiment>
Next, a solid oxide fuel cell system according to a second embodiment will be described with reference to FIG. In the second embodiment mobile phone, correction is made in relation to the second vaporizer. In the following embodiments, members substantially the same as those in the first embodiment described above are given the same reference numerals, and descriptions thereof are omitted.

  In FIG. 4, in the solid oxide fuel cell system 2 </ b> A of the second embodiment, a carburetor unit 142 is attached to the upper part of the side wall of the fuel cell housing 60, and the carburetor unit 142 has a first inside the unit housing 144. Two vaporizers 12 are accommodated. The second vaporizer 12 may be the same as that described above, and includes a reformed water passage 70 through which reformed water flows and an exhaust gas passage 72 through which combustion exhaust gas flows. The reforming water flow path 70 extends vertically downward, and the reforming water flow path 18 connecting the second vaporizer 12 and the first vaporizer 10 extends downward with a downwardly inclined slope.

  The unit housing 144 is provided with a heat insulating material 146 so as to cover the entire inner surface thereof, and the exhaust gas supply passage 56A through which the combustion exhaust gas flows is led directly from the fuel cell housing 60 to the unit housing 144. The unit housing 144 is covered with a heat insulating material 146 and connected to the second vaporizer 12 (that is, the exhaust gas flow path 72). Further, the reforming water flow path 18A through which the reforming water (including water vapor) flows is covered with a heat insulating material 146 in the unit housing 144, and is directly guided to the fuel cell housing 60 from the unit housing 144. Connected to the vaporizer 10.

  In this embodiment, an auxiliary combustion housing 148 is provided in a portion (specifically, upstream of the second carburetor 12) located in the unit housing 144 in the exhaust gas supply passage 56A, and this auxiliary combustion housing 148. Is also covered with a heat insulating material 146. The auxiliary combustion housing 148 defines a catalytic combustion chamber 150 having a larger cross-sectional area than the exhaust gas supply passage 56A, and the catalytic combustion chamber 150 is filled with the combustion catalyst 152. By providing the catalytic combustion chamber 150 on the upstream side of the second carburetor 12 in this manner, unburned gas in the combustion exhaust gas can be burned and the combustion heat is reformed in the second carburetor 12. It can be used for water vaporization of water. If the combustion heat of the unburned gas is not used for steam vaporization, the auxiliary combustion housing 148 can be provided in the exhaust gas discharge passage 58 on the downstream side of the second vaporizer 12.

  In this embodiment, a preheating heating means 154 composed of, for example, an electric heater is provided in association with the catalytic combustion chamber 150 (in other words, the combustion catalyst 152). The preheating heating means 154 is provided so as to surround the periphery of the auxiliary combustion housing 148, and heats the combustion catalyst 152 in the catalytic combustion chamber 150 and the combustion exhaust gas flowing therethrough. The other configuration of the second embodiment is the same as that of the first embodiment described above.

  In the solid oxide fuel cell system according to the second embodiment, the combustion exhaust gas from the combustion zone 54 passes from the fuel cell housing 60 side to the catalyst combustion chamber 150 on the unit housing 144 side through the exhaust gas supply passage 56A. To be sent to. In the catalytic combustion chamber 150, the combustion catalyst 152 burns unburned gas in the combustion exhaust gas. The combustion heat promotes activation of the combustion catalyst 152 and the combustion exhaust gas is heated to The reformed water flowing through the reforming water flow path 70 of the second vaporizer 12 is heated and vaporized by the combustion exhaust gas supplied to the two vaporizer 12 (its exhaust gas flow path 72) and heated in this way, and thus The reformed water can be vaporized by using the combustion heat of the unburned gas in the combustion exhaust gas. As a result, the power generation performance can be stabilized and the power generation efficiency can be increased.

  This preheating heating means 154 is operated especially when the temperature of the combustion catalyst 152 is low, such as when the fuel cell system 2 is started. When operated in this way, the preheating heating means 154 heats the combustion catalyst 152, and the combustion catalyst 152 is activated, so that unburned gas can be combusted at the time of startup or the like.

  In relation to this second vaporizer, it can also be configured as shown in FIG. In FIG. 5, in this modification, the vaporizer unit 142D includes a unit housing 144D, and the second vaporizer 12D is accommodated in the unit housing 144D. For example, the second vaporizer 12D is shown in FIG. It is the thing of the structure similar to what is shown.

  In this modification, instead of providing the catalyst combustion chamber 150, the exhaust gas flow path 72 of the second vaporizer 12D is filled with the combustion catalyst 152. In relation to this, preheating heating means 154D is disposed around the exhaust gas flow path 72 (that is, the outer peripheral side of the outer cylindrical member 112D), and this preheating heating means 154D is, for example, a ring-shaped electric Consists of a heater. Further, the second vaporizer 12D and the preheating heating means 154D are covered with a heat insulating material 146D and accommodated in the unit housing 144D.

  In this modification, the exhaust gas flow path 72 of the second vaporizer 12D is filled with the combustion catalyst 152, so that the configuration of the vaporizer unit 142D can be simplified and the size thereof can be reduced. In addition, since the preheating heating unit 154D heats the entire second vaporizer 12D (specifically, the combustion catalyst 152 filled in the exhaust gas passage 72 and the reformed water flowing through the reformed water passage 70), The vaporizer unit 142D can be efficiently heated by effectively using the heat of the preheating heating means 154D.

  In the embodiment shown in FIG. 4, preheating heating means 154 is provided in relation to the combustion catalyst 152, and in the embodiment shown in FIG. 5, preheating heating means in relation to the combustion catalyst 152 and the second vaporizer 12D. 154D is provided, but is not limited to such a configuration, and is related to the reformed water supply flow path 18A or related to the reformed water supply flow path 18A and the second vaporizer 12 (12D). In addition, a preheating heating means 154 (154D) may be provided in relation to the combustion catalyst 152, the second vaporizer 12 (12D), and the reforming water supply passage 18A.

  In the embodiment shown in FIG. 4, the combustion catalyst 152 is provided in the exhaust gas supply passage 56A (specifically, the catalytic combustion chamber 150). In the embodiment shown in FIG. 5, the second carburetor 12D is provided. Although the combustion catalyst 152 is provided in the exhaust gas flow path 70, the combustion catalyst 152 may be provided in both the exhaust gas supply flow path 56A and the exhaust gas flow path 70 of the second vaporizer 12D.

  In the embodiment of FIG. 4, temperature detection means 160 is further provided at the inflow portion of the reforming water supply flow path 18A. The temperature detection means 160 detects the temperature of the reformed water (including water vapor) flowing toward the first vaporizer 10 in the reformed water supply flow path 18A, and based on the detected temperature, the raw fuel gas It is desirable to control the supply flow rate of at least one of reforming water and air and / or the power generation output of the cell stack 6, so that the power generation reaction in the cell stack 6 and the combustion zone 54 can be controlled in this way. It is possible to stabilize the combustion of the surplus fuel gas and the vaporization of the reformed water vapor. As the temperature detection means 160, for example, a thermocouple can be used, and for example, it may be provided at the outflow portion of the reforming water flow path 70 of the second vaporizer 12.

  In the steady power generation state of the cell stack 6, the temperature of the temperature detecting means 160 is controlled to be kept within a predetermined temperature range, for example, 140 to 160 ° C., and the detected temperature of the temperature detecting means 160 is within this predetermined temperature range. When the fuel gas is higher (or lower) than the raw fuel gas, the supply flow rate of the raw fuel gas is decreased (or increased) as the combustion amount of the surplus fuel gas in the combustion zone 54 is large (or small). The gas supply pump 36 (see FIG. 1) is controlled, and with respect to the reforming water, the amount of reforming water supplied is small (or large), and steam vaporization in the second vaporizer 12 is excessive (or insufficient). 1), it is necessary to control the water supply pump 26 (see FIG. 1) so as to increase (or decrease) the supply flow rate of reforming water, and to reduce (or increase) the temperature of the combustion exhaust gas with respect to air. Assuming that the blower blower 50 is controlled so that the supply flow rate of air increases (decreases), and the power generation output of the cell stack 6 is small (or large), a large amount of surplus fuel gas is generated. However, it is desirable to adjust the power generation output so that the fuel utilization rate increases (or decreases).

  Further, the preheating heating unit 154 (154D) may be controlled based on the temperature detected by the temperature detection unit 160. In this case, when the temperature detected by the temperature detection unit 160 rises above a predetermined temperature range, Control is made so that the heating amount by the preheating heating means 154 (154D) is lowered, and when the detected temperature falls below a predetermined temperature range, the heating amount by the preheating heating means 154 (154D) is controlled so as to be raised. By controlling the heating, the water vaporization state in the second vaporizer 12 (12D) can be stabilized, and the power generation state in the cell stack 6 can be stabilized.

  In addition, in a steady power generation state with a high fuel utilization rate (for example, the fuel utilization rate is 75% or more), the detected temperature of the temperature detecting means 160 has been rapidly decreased (for example, the temperature variation converted per minute). If the rate is, for example, 5 ° C./min or more), the amount of surplus fuel gas in the combustion zone 54 is small, and it is estimated that poor vaporization will occur in the future. It is desirable to control the supply amount of the raw fuel gas so as to make it smaller. By controlling the fuel utilization rate in this way, deterioration of the vaporization of water vapor in the second vaporizer 12D can be prevented, and the cell stack 6 The power generation state can be stabilized.

  Further, it is possible to control as follows using the detected temperature of the temperature detecting means 160. When this detected temperature exceeds a predetermined temperature (for example, set to around 130 ° C.), it can be determined that all the reformed water supplied to the second vaporizer 12 has been vaporized, and in such a case The supply amount of the raw fuel gas supplied from the fuel gas supply flow path 32 to the cell stack 6 is reduced (thereby reducing the combustion amount of surplus fuel gas in the combustion zone 54), and thus the raw fuel It can be controlled to increase the fuel utilization of the gas. In this case, the fuel utilization rate in the fuel cell system can be controlled to be increased by, for example, about 5 to 10 points, and as a result, the power generation efficiency can be increased while maintaining the operating temperature of the cell stack 6 at a high temperature. .

<Third Embodiment>
Next, a solid oxide fuel cell system according to a third embodiment will be described with reference to FIG. In the third embodiment, the fuel cell housing has a double housing structure.

  In FIG. 6, in the illustrated solid oxide fuel cell system 2 </ b> E, the fuel cell housing 60 </ b> E includes an inner housing 162 disposed on the inner side and an outer housing 164 that covers the inner housing 162. The inner housing 162 is formed of a highly heat-resistant metal material such as stainless steel, for example, and the inner housing 162 defines an inner space 166, and the cell stack 6, the combustion zone 54, the reformer 4 is formed in the inner space 166. The first vaporizer 10 and the oxidant preheater 52 are disposed. The outer housing 164 includes a frame structure made of a metal material such as iron or stainless steel, and a heat insulating material (not shown) is disposed so as to cover the inner surface of the frame structure. The outer housing 164 is configured by being held and fixed to the body. The outer housing 164 defines an outer space 168 with the inner housing 162, and the second vaporizer 12E is disposed in the outer space 168.

  In this embodiment, the inner space 166 and the outer space 168 are kept at a high temperature, and the hot heat in the inner space 166 is transferred to the outer space 168 via the inner housing 166, which is referred to herein as the inner housing. 162 functions as a fuel cell housing.

  Also in the third embodiment, the reforming water supply passage 18E (for example, composed of reforming water piping) that connects the second vaporizer 12E and the first vaporizer 10 is provided with the inner housing 162. It penetrates and extends vertically downward and is connected to the first vaporizer 10. In addition, you may comprise this reforming water supply flow path 18E so that it may extend below in the downward gradient from the 2nd vaporizer 12E to the 1st vaporizer 10, as mentioned above.

  Furthermore, in this embodiment, the reforming water supply channel 24 and the fuel gas supply channel 32 are connected to the second vaporizer 12E (specifically, the reforming water channel 70E), and the reforming water and the raw fuel gas are supplied. Is supplied to the second vaporizer 12E. In the third embodiment, as in the above-described embodiment, the fuel gas supply flow path 32 is connected to the first vaporizer 10 so that the raw fuel gas is supplied to the first vaporizer 10. Also good. Other configurations of the third embodiment are substantially the same as those of the first embodiment described above.

  In the third embodiment, the raw fuel gas and the reformed water are supplied to the reformed water flow path 70E of the second vaporizer 12E. In the second vaporizer 12E, heat exchange is performed between the reformed water flowing in the reformed water flow path 70E and the fuel gas and the combustion exhaust gas flowing in the exhaust gas flow path 72E. Steam vaporization is performed, and this steam vaporization is also performed using the heat in the outer space 168, and this steam vaporization can be performed efficiently. Further, while the reformed water (including vaporized water vapor) flows through the reformed water flow path 70E, the vaporized water vapor and the raw fuel gas are mixed, and the mixed fuel gas is heated.

  The heated mixed fuel gas and the non-vaporized reformed water are fed to the first vaporizer 10 through the reformed water feed passage 18E, and the remaining vaporized steam of the reformed water is vaporized in the second vaporizer 10. At the same time, the generated water vapor and the mixed fuel gas are further mixed, and the mixed fuel gas thus mixed is supplied to the reformer 4 to perform the steam reforming of the fuel gas.

Also in this embodiment, since the reforming water supply flow path 18E is configured vertically (or descending slope), the retention of the reforming water in the reforming water supply flow path 18E can be reduced, Thereby, the fluctuation range of S / C (steam / carbon ratio) can be reduced. In addition, since the second vaporizer 12E and the reforming water supply passage 16E are maintained at a high temperature, the heat of the surroundings (the outer space 168 and the inner space 166) is used for vaporizing the reforming water vapor. This can be performed efficiently.
Although various embodiments of the solid oxide fuel cell system according to the present invention have been described above, the present invention is not limited to such embodiments, and various modifications and corrections can be made without departing from the scope of the present invention. Is possible.

2, 2A, 2E Solid oxide fuel cell system 4 Reformer 6 Cell stack 10 First vaporizer 12, 12A, 12B, 12C, 12D, 12E Second vaporizer 18, 18A Reformed water supply flow path 24 Reformed water supply flow path 32 Fuel gas supply flow path 48 Oxidizing material supply flow path 52 Oxidizing material preheater 54 Combustion zone 56, 56A Exhaust gas supply flow path 60, 60E Fuel cell housing 70 Reformed water flow path 72 Exhaust gas flow Path 142, 142D Vaporizer unit 150 Catalytic combustion chamber 152 Combustion catalyst 154, 154D Preheating heater 160 Temperature detection means 162 Inner housing 164 Outer housing

Claims (8)

A reformer for reforming and reacting hydrocarbon-based fuel gas and water vapor from reformed water, and a fuel that generates electricity by oxidizing and reducing the reformed fuel gas and the oxidizing material reformed by the reformer A cell stack having battery cells, a combustion zone for burning surplus fuel gas that does not contribute to power generation in the cell stack, and a combustion exhaust gas discharged from the oxidizing material fed to the cell stack through the combustion zone A solid oxide fuel cell system comprising: an oxidant preheater for exchanging heat with the fuel cell; and a fuel cell housing for housing the reformer, the cell stack, and the oxidant preheater Because
First and second vaporizers are provided for vaporizing the reformed water to generate water vapor. The first vaporizer is accommodated in the fuel cell housing and is burned by surplus fuel gas in the combustion zone. The second carburetor is disposed outside the fuel cell housing and heated by combustion exhaust gas discharged from the combustion zone through the oxidant preheater, and the reformed water is heated by the second carburetor. To the first vaporizer through the reforming water supply flow path,
The second vaporizer is disposed above the first vaporizer, and the reforming water supply passage extends from the second vaporizer to the first vaporizer with a vertical or downward gradient. A solid oxide fuel cell system.   The second carburetor includes a carburetor main body that defines a reformed water flow path through which reformed water flows and an exhaust gas flow path through which combustion exhaust gas flows, and a reformed water inflow portion is provided at an upper end of the carburetor main body. A reforming water outflow portion is provided at a lower end thereof, the reforming water outflow portion is communicated with the reforming water supply passage, and the reforming water passage is connected to the reforming water inflow portion from the reforming water inflow portion. 2. The solid oxide fuel cell system according to claim 1, wherein the solid oxide fuel cell system extends vertically or downwardly to the water outflow portion.   The oxidant preheater and the exhaust gas flow path of the second vaporizer are connected via an exhaust gas supply flow path, and the exhaust gas supply flow path and / or the exhaust gas of the second vaporizer. The solid oxide fuel cell system according to claim 2, wherein a combustion catalyst is disposed in the flow path.   In relation to at least one of the second vaporizer, the reforming water supply flow path, and the combustion catalyst, preheating heating means for heating at least one of them is provided. The solid oxide fuel cell system according to claim 3.   Temperature detection means is disposed in at least one place of the second vaporizer, the reforming water supply flow path, and the exhaust gas supply flow path, and the hydrocarbon fuel is based on the detected temperature of the temperature detection means. 5. The solid oxide fuel cell system according to claim 3, wherein a supply flow rate of at least one of gas, reforming water, and air and / or a power generation output of the cell stack is controlled.   Temperature detection means is disposed in at least one location of the second vaporizer, the reforming water supply flow path, and the exhaust gas supply flow path, and the temperature detection means is detected in a steady operation state at a high fuel utilization rate. 5. The solid oxide fuel cell system according to claim 3, wherein when the temperature rapidly decreases, control is performed to increase a fuel utilization rate in the system.   Temperature detection means is provided in at least one location of the second vaporizer, the reforming water supply flow path, and the exhaust gas supply flow path. Based on the temperature detected by the temperature detection means, the preheating heating means The solid oxide fuel cell system according to claim 4, wherein the heating amount is controlled. A fuel gas supply flow path for supplying hydrocarbon fuel gas is connected to the first or second vaporizer, and the hydrocarbon fuel gas includes water vapor generated in the first or second vaporizer. The solid oxide fuel cell system according to claim 1, wherein the solid oxide fuel cell system is mixed.

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