JP4972861B2 - Method for starting fuel cell stack structure and fuel cell stack structure - Google Patents

Description

    The present invention relates to a method for starting a fuel cell stack structure formed by stacking solid oxide fuel cells, and a fuel cell stack structure.

  When the fuel cell stack structure as described above is mounted on an automobile, since the start and stop are frequently repeated, it is desirable that the heat capacity is small, but in order to ensure the strength and sealing performance of the gas flow path portion, Therefore, a portion having a large heat capacity is inevitably formed.

  In such a portion having a large heat capacity, the temperature rise is delayed at the time of startup, and in a portion having a small heat capacity, the portion is heated rapidly. As a result, the temperature difference becomes large and stress concentration occurs, causing damage to the separator or single cell of the solid oxide fuel cell.

  In addition, since the temperature of the gas flow path portion having a large heat capacity is low, the temperature of the power generation gas is lowered, the output is lowered, and the output varies due to uneven temperature.

Conventionally, in order to eliminate the above-mentioned problems, the fuel gas is burned with a burner and the high-temperature flue gas is flowed through the fuel electrode passage and heated. The start-up method is designed to maintain the reducibility of the fuel electrode, and the catalytic combustion section is provided in the air flow path inside the cylindrical cell so that not only high-temperature gas is sent, but also the catalytic combustion section A power generation system that efficiently transfers heat to a cell has been proposed.
JP-A-11-162492 JP 2004-119298 A

  However, in the former, since the heat capacity of the object is large in the former activation method, heating takes time, and the temperature rise is delayed on the downstream side with respect to the upstream side of the gas flow. In the latter power generation system, there is a problem that it is difficult to manufacture the cell because it is limited to the cylindrical cell, and the stack density cannot be increased. Has become a conventional problem.

  The present invention has been made paying attention to the above-described conventional problems, and at the time of start-up, the temperature difference between the large heat capacity portion and the small heat capacity portion is reduced by improving the temperature rising rate of the large heat capacity portion. The fuel cell stack structure starting method and the fuel cell stack structure can prevent the stress concentration from occurring and, in addition, can prevent the gas temperature from decreasing due to the low temperature of the gas flow path The purpose is to provide.

  Therefore, the inventors selectively heated the gas flow path portion having a large heat capacity, while the portion having a small heat capacity is heated by heat conduction from the portion having a large heat capacity, or a portion having a large heat capacity. It has been found that the above object can be achieved by changing the flow of the high-temperature gas so that the temperature of the small portion rises after the temperature rises.

That is, the present invention provides two metal thin plate separators having a gas introduction hole and a gas discharge hole in the center, and a gas introduction and discharge to a space formed in the center between both separators and formed between both separators. And a plurality of solid oxide fuel cells including a single cell of a solid electrolyte type that is housed in a space formed between both separators and one surface of which is exposed to the outside. , the center of the solid oxide fuel cell, the gas introduction hole, and communicates the 及 beauty central channel parts so as to form at least one gas channel, each of the solid oxide fuel cell from the gas flow path When starting the fuel cell stack structure that supplies gas to the space, the central part of the solid oxide fuel cell in which the center of each separator and the central flow path component are polymerized is the part with a large heat capacity. On the other hand, the outer peripheral part of each separator is a part having a small heat capacity, and at the stage of raising the temperature of the plurality of solid oxide fuel cells, the part having a large heat capacity is selectively heated. The configuration of the starting method of the fuel cell stack structure is used as means for solving the above-described conventional problems.

On the other hand, the fuel cell stack structure of the present invention has two metal thin plate separators having a gas introduction hole and a gas discharge hole in the center, and a space formed in the center between both separators and formed between both separators. A plurality of solid electrolyte fuels including a central flow path component that introduces and discharges gas and a solid electrolyte type single cell that is accommodated in a space formed between both separators and has one surface exposed to the outside made by laminating battery, these in the middle of the solid oxide fuel cell, the gas introduction hole, thereby forming at least one gas flow path to communicate with each other 及 beauty central channel parts, solids from the gas flow path In the fuel cell stack structure for supplying gas to each space of the electrolyte fuel cell, the central portion of the solid oxide fuel cell in which the center of each separator and the central flow path component are polymerized is a portion having a large heat capacity On the other hand, the outer peripheral part of each separator is a part having a small heat capacity, and at the stage of raising the temperature of the plurality of solid oxide fuel cells at the time of startup, the part having a large heat capacity can be selectively heated. The structure of the fuel cell stack structure is a means for solving the above-described conventional problems.

In the present invention, by disposing a central flow path component in the center between two sheet metal separators, for example, in the case of a fuel cell stack structure formed by forming a metal gas flow path at the center, Ri is Na large heat capacity in the vicinity of the center of the center and the central passage part of the separators is polymerized, the thermal capacity of the outer peripheral portion of the metal thin plate separator is that a small hand.

  At this time, if heat is supplied from the outer peripheral side of the stack structure with a heater or high-temperature gas, the outer peripheral portion having a small heat capacity and close to the heat source is heated in advance, and the temperature rise is delayed near the center having a large heat capacity. Moreover, even if a high-temperature gas is caused to flow from the center through the same flow path as that during power generation, the portion having a small heat capacity is heated in advance.

  The size of the gas channel at the center of the stack structure is 15 to 25 mmφ, the size of the large heat capacity including the discharge channel is 40 to 60 mmφ, and the thickness of one solid oxide fuel cell is about 1 to 5 mm. In the present invention, a portion having a large heat capacity of 40 to 60 mmφ is selectively heated.

In the following description, it is assumed that the power generation system flows fuel gas into the interior space of the solid oxide fuel cell and air gas flows outside the solid oxide fuel cell. Even if it is replaced, the same applies. In addition, the stack structure also, that describes the center channel type stacked structure forming a metallic gas passage in the center assumption.

According to the present invention, since it is configured as described above, at the time of start-up, it is possible to improve the rate of temperature rise in the portion having a large heat capacity that is the central portion of the solid oxide fuel cell . It is possible to suppress the occurrence of stress concentration due to a temperature difference from the part with a small heat capacity that is the outer peripheral part, and in addition, it is possible to prevent the temperature drop of the gas flowing through the gas flow path. Is brought about.

In the present invention, in order to selectively heat a portion having a large heat capacity, which is the central portion of the solid oxide fuel cell, a configuration in which a high-temperature gas is preferentially flowed and heated to a portion having a large heat capacity can be employed. in addition, it is possible to employ a configuration to heat a heating element provided on a large part of the heat capacity, in the former case, a large portion of the heat capacity by heat exchange is heated up Atsushi Nobori rate of the gas, as a result As a result, the heating rate of the entire stack structure is increased.

  In the latter case, for example, when a through-hole in the vertical direction is formed in the central portion of the solid oxide fuel cell and a heater wire (resistance wire) is inserted into the through-hole, the central portion is heated and the rate of temperature rise is increased. As a heater wire, a general heater wire such as Ni—Cr can be used as the heater wire. With this configuration, there is no need to install a circulation channel or the like, and the system can be simplified. Note that the higher the number of heater wires and the greater the amount of heat generated by the heater, the higher the rate of temperature rise at the center, but the power consumption associated with the temperature rise increases.

  Here, in the fuel cell stack structure, as shown in FIG. 15, the hot gas ga passes through the flow path portion A having a large heat capacity and is distributed to the stacked solid oxide fuel cells 101. Then, as shown in FIG. 16, the generated gas gb that has passed through the solid oxide fuel cell 101 is discharged out of the solid oxide fuel cell 101 by the exhaust passage B formed in the central portion having a large heat capacity, This is the flow path during power generation.

In contrast, without passing through the hot gas solid oxide fuel cell, forming a short-circuit flow path so as to exhaust to the outside only through the large central portion of the heat capacity, heating and select the center component To get.

Therefore, in the present invention, a short-circuit channel that discharges most of the high-temperature gas to be supplied to each space of the solid oxide fuel cell from the gas channel, and a solid electrolyte fuel from the gas channel by closing the short-circuit channel It employs a configuration that includes a flow path changing means for returning to the state for supplying hot gas to the space of the battery, at the time of startup, heating the large parts of the Ah Ru heat capacity in the central portion of the solid oxide fuel cell It was.

  If this structure is used, it is not necessary to install a complicated movable part etc. in the part used as a high temperature, and the gas inflow part, ie, a heating part, can be changed easily.

In this case, if a circulation flow path is provided to circulate the hot gas discharged from the short-circuit flow path back to the gas flow path so that the high-temperature gas can be circulated, the amount of exhaust gas is reduced and the central portion is efficiently raised. It will be warm.

The ratio of the high-temperature gas flowing through the solid oxide fuel cell and the short-circuit channel is determined by the magnitude of each resistance between the channel and the short-circuit channel to the solid oxide fuel cell. The gas supply port to the solid oxide fuel cell has a smaller opening area than the gas flow path, and a mesh or foam current collector is inserted in the internal space of the solid oxide fuel cell. The flow path resistance is large. Accordingly, the flow path resistance of the short flow path becomes smaller than the flow path resistance of the solid electrolyte type fuel cell, the flow of short-circuit flow path is dominant, as a result, the center component is heated.

  The gas flow flowing into the short-circuit channel, that is, the opening degree of the valve as the exhaust-side channel changing means is preferably switched according to time or the temperature of the solid oxide fuel cell. In the present invention, the solid oxide fuel cell A temperature sensor disposed in at least one of the temperature sensor, and a control unit that adjusts the flow rate of the hot gas discharged through the short-circuit channel by operating the channel changing means based on the temperature detected by the temperature sensor Can be adopted.

  For example, thermocouples as temperature sensors are fixed at two locations, a portion having a large heat capacity (center portion) and a portion having a small heat capacity (outer peripheral portion), and the temperature at each location is monitored. If the valve on the exhaust side is closed when the temperature of the central part becomes equal to or higher than a certain temperature, there is no place for the gas to flow into the solid oxide fuel cell. As a result, it is possible to heat the outer peripheral portion in succession to the heating of the central portion, that is, the whole can be rapidly heated, and the temperature distribution at the time of temperature rise becomes uniform.

  Therefore, the temperature increase rate at the outer peripheral portion can be adjusted by the opening degree of the valve on the exhaust side. As for the rate of temperature rise in the central part, if the flow rate of the high-temperature gas flowing in the central gas flow path is excessively high, heat exchange is difficult and the rate becomes low. Therefore, it may be necessary to adjust the gas flow rate on the exhaust side.

  At this time, if there is no difference in resistance between the flow path to the solid oxide fuel cell and the short-circuit flow path, the amount of hot gas flowing into the solid oxide fuel cell increases, and the central portion is selectively heated. It becomes impossible. In the case of such a stack structure, it is desirable to provide an opening / closing means such as a shutter for opening / closing a gas supply port that communicates the gas flow path and the space of the solid oxide fuel cell. Even if there is no resistance difference in the path, the heating part can be changed.

  For example, a metal cylinder that is in close contact with the wall surface of the central gas flow path is prepared, and a hole is provided in the position corresponding to the gas supply port in the metal cylinder, and the cylinder is moved up and down or rotated, whereby the gas supply port Can be opened and closed.

  In addition, when one end of a small piece made of a laminate of materials having different thermal expansion coefficients is joined in the vicinity of the gas supply port or inside the gas supply port, the gas is supplied by deformation due to the difference in thermal expansion of the small piece when the central portion is heated. If the mouth is opened, the same shutter function as described above can be obtained. Specifically, when a ceramic material such as alumina is formed to a thickness of about 10 μm on a heat-resistant stainless steel having a thickness of about 50 μm, thermal deformation due to a difference in thermal expansion occurs as the temperature rises. It is desirable to use a sputtering method, a CVD method, or a thermal spraying method AD for the ceramic film formation.

  In addition, it is possible to adopt a configuration that increases the heat receiving area by forming irregularities such as counterbore on the road wall surface of the gas flow path, and in this case, turbulence tends to occur as the heat receiving area increases, Therefore, the residence time on the wall surface of the gas flow path of the high-temperature gas becomes long, and heat exchange becomes easy. In particular, since the flanges installed above and below the stack structure also have a large heat capacity, it is desirable to form irregularities on the wall surface of the gas flow path in the vicinity.

  Further, in the present invention, heat is generated by putting fuel gas and air gas into a combustor to burn, and using this as a heat medium, the gas flowing in the gas flow path is heated by a heat exchanger, and the stack structure A structure for forming a high-temperature gas for temperature rise, that is, a combustor that burns fuel gas, and a heat exchanger that heats the gas flowing in the gas flow path with the combustion heat generated in the combustor to form a high-temperature gas A configuration can be adopted.

  When this configuration is adopted, high-temperature gas can be obtained without using any gas other than fuel gas or electricity. At this time, the heating gas may be either an oxidant gas or a fuel gas, which is suitable when the inside of the solid oxide fuel cell is a fuel electrode and it is desired to raise the temperature by introducing a reducing gas.

  Further, in the present invention, the high-temperature combustion exhaust gas generated in the combustor can be used as it is as a heating gas, that is, the combustor that flows the high-temperature combustion exhaust gas generated by burning the fuel gas to the gas flow path. A high-temperature gas can be obtained without using a gas other than electricity or fuel gas. However, since the oxidizing gas flows into the inside of the solid oxide fuel cell, when the inside is a fuel electrode, it is necessary to pay attention to the oxidation of the fuel electrode, the current collector, and the coating inside the separator.

  Furthermore, in the present invention, an electric heating mechanism can be provided that is installed in a gas pipe coupled to the gas flow path and heats the gas flowing through the gas flow path. Hot gas is obtained by winding a resistance wire or an electric heater around the outside of the gas pipe connected to the path. Also in this case, the heating gas may be either an oxidant gas or a fuel gas, which is suitable when the inside of the solid oxide fuel cell is a fuel electrode and it is desired to raise the temperature by introducing a reducing gas. .

  Furthermore, in the fuel cell stack structure of the present invention, after heating the central portion, the solid oxide fuel cell can be heated by changing the flow path, but the heat capacity of the solid oxide fuel cell is small. The temperature can be raised following the center portion by heat conduction from the center portion.

That is, the solid electrolyte type fuel cell a large portion other than the region of Ah Ru heat capacity in the central portion by the following sheet metal forming 200μm in the distant portion from the gas flow path of the solid oxide fuel cell can be heated by thermal conduction In this case, the fuel cell stack structure can be heated without the need for a functional component such as a shutter, and the gas flow path follows the temperature change in the central portion. Therefore, it is possible to raise the temperature at a high speed.

  Furthermore, in the fuel cell stack structure of the present invention, the separator of the solid oxide fuel cell and the gas flow path penetrating the separator are formed of a heat-resistant alloy material containing Ni or Fe as a main component and Cr. If this configuration is adopted, the long-term durability of the solid oxide fuel cell can be secured.

  As a material, it is preferable to use an Fe—Cr alloy such as SUS316L, SUS430, ZMG, or FeCrW in a solid oxide fuel cell equipped with a single cell having a high operating temperature of 400 ° C. or higher. Although Ni-based alloys such as Inconel can be used, it is necessary to select a material that reduces the mismatch in thermal expansion coefficient with the material of the single cell fixed to the separator.

Furthermore, in the fuel cell stack structure of the present invention, an increase in the thickness of a small portion of the heat capacity of the solid oxide fuel cell, and a this leads to an increase in weight and thermal capacity, as thin as possible is desirable. However, if the thickness is too thin, the strength is reduced and the holding of the cell is hindered. Therefore, the outer peripheral portion of each separator is formed of a rolled thin plate having a thickness of 0.05 to 0.5 mm. It is desirable to do.

  With this configuration, it is possible to increase the rate of temperature rise, heat transfer from the heated central part is good, and it is possible to raise the temperature following the temperature change in the central part. Is also suitable for in-vehicle use.

Furthermore, in the fuel cell stack structure of the present invention, a solid oxide single cell can be mounted on a portion having a small heat capacity, which is the outer peripheral portion of each separator of the solid oxide fuel cell. Since it is resistant to thermal shocks at start and stop and has high structural durability, it is suitable for in-vehicle use.

  The single cell may be an electrode support type or an electrolyte support type. The shape of the single cell is not particularly limited as long as it is a size that fits into a portion having a small heat capacity of the separator. Since it is a metal separator, the operating temperature is desirably 700 ° C. or lower.

  EXAMPLES Hereinafter, although an Example demonstrates this invention still in detail, this invention is not limited to a following example.

  1 to 5 show an embodiment of a fuel cell stack structure according to the present invention. As shown in FIG. 1, this fuel cell stack structure 1 includes 10 solid oxide fuel cells 10. It is made up of layers. The overlapping solid oxide fuel cells 10 are bonded to each other by a ceramic adhesive mainly composed of alumina. At this time, a gas seal and insulation between them are also secured. In this fuel cell stack structure 1, Electric power is generated by introducing fuel gas into the solid oxide fuel cell 10 and flowing air gas outside the solid oxide fuel cell 10.

  As shown in FIG. 2, the solid oxide fuel cell 10 has a plurality of single cells 11, a circular thin metal plate, and has a gas introduction hole 12a and a gas discharge hole 12b at the center, and the single cell. 11 and the other separator 13 having the same circular metal sheet shape as the one separator 12 and having a gas introduction hole 13a and a gas discharge hole 13b in the center portion. The separators 12 and 13 are joined to each other in a state of facing each other.

  In this case, a central flow path component 14 for supplying and discharging gas to and from the space S formed between the separators 12 and 13 is provided at each central portion of both separators 12 and 13. The component 14 includes a gas discharge portion 15 having a gas discharge port 15 b communicating with the gas discharge hole 12 b of one separator 12 and a gas introduction portion 16 having a gas introduction port 16 a communicating with the gas introduction hole 13 a of the other separator 13. It is made by joining.

In this example, SUS430 having an outer diameter of 120 mm and a wall thickness of 0.1 mm was used for the separators 12 and 13 having a circular metal thin plate shape, and this rolled plate was pressed to form a diaphragm shape. Moreover, SUS430 was used also for the gas discharge part 15 and the gas introduction part 16 of the central flow path component 14, and the gas discharge port 15b and the gas introduction port 16a were formed by etching or MIM. The gas discharge part 15 and the gas introduction part 16 are both joined to the separators 12 and 13 by diffusion joining. Further, the single cell 11 is fixed to one separator 12 with one electrode exposed to the outside.

  In this fuel cell stack structure 1, as shown in FIGS. 3 and 4, the upper end of the gas flow path 2 formed at the center by stacking the solid oxide fuel cells 10 is supplied via a flange 3U. A side gas pipe 4 is connected. On the other hand, at the lower end of the gas passage 2, a short-circuit passage 22 having an exhaust valve 21 as a passage changing means for controlling the flow rate of the exhaust gas is provided via a flange 3L. Connected.

  When the fuel cell stack structure 1 is started up, the short-circuit channel 22 opens the exhaust valve 21 (by setting the state shown in FIG. 3) from the gas channel 2 to each space of the solid oxide fuel cell 10. Most of the high-temperature gas G to be supplied to S is discharged as it is, and only the portion with a large heat capacity located in the vicinity of the gas flow path 2 of the solid oxide fuel cell 10 is heated.

  In the fuel cell stack structure 1, after raising the temperature of a portion having a large heat capacity located in the vicinity of the gas flow path 2 of the solid oxide fuel cell 10, the exhaust valve 21 is closed (shown in FIG. 4). In this state, the high temperature gas G is supplied to each space S of the solid oxide fuel cell 10 so that the portion having a small heat capacity is heated to be in a state where power can be generated. .

  Further, as shown in FIG. 5, the fuel cell stack structure 1 includes a combustor 23 that combusts fuel gas, and a gas flow path 2 through combustion gas generated in the combustor 23 via a supply-side gas pipe 4. In this embodiment, the high-temperature gas discharged from the short-circuit channel 22 is also returned to the heat exchanger 24 via the circulation channel 25. Reheated for use.

  Further, in this fuel cell stack structure 1, as shown in the enlarged circle of FIG. 3, the heat receiving power is obtained by forming saw-tooth-like irregularities 26 on the road wall surface 2a of the gas flow path 2 near the flange 3L having a large heat capacity. The area is increased. That is, heat exchange is facilitated by making the turbulent flow easy to occur with the expansion of the heat receiving area and extending the residence time of the high-temperature gas on the wall surface 2a of the gas flow path 2.

  In the fuel cell stack structure 1 described above, the short-circuit channel 22 having the exhaust valve 21 as the channel changing means for controlling the flow rate of the exhaust gas is connected to the lower end of the gas channel 2. Thus, if the exhaust valve 21 is operated to control the flow rate of the exhaust gas, the temperature rising speed of the portion having a large heat capacity can be selectively improved at the time of start-up. As a result, the portion having a large heat capacity and the portion having a small heat capacity can be improved. It is possible to suppress the occurrence of stress concentration due to the temperature difference, and in addition, it is possible to prevent the temperature drop of the gas flowing through the gas flow path.

  Further, since the opening / closing operation of the exhaust valve 21 can selectively heat a portion having a large heat capacity, the heating portion can be easily changed without installing a complicated movable portion or the like in a portion that becomes high in temperature. It will be.

  Furthermore, in the fuel cell stack structure 1 described above, the circulation passage 25 for circulating the high temperature gas discharged from the short-circuit passage 22 back to the heat exchanger 24 is provided, so that the amount of exhaust gas is reduced and the center efficiently. Only the portion can be heated.

  Furthermore, the fuel cell stack structure 1 described above includes a heat exchanger 24 that heats the gas flowing through the gas flow path 2 with the combustion heat generated in the combustor 23 that combusts the fuel gas to form a high-temperature gas. Therefore, a high-temperature gas can be obtained without using any gas other than fuel gas or electricity. At this time, the heating gas may be either an oxidant gas or a fuel gas, which is suitable when the inside of the solid oxide fuel cell 10 is the fuel electrode and it is desired to raise the temperature by introducing a reducing gas. .

  The fuel cell stack structure 1 includes a combustor 23 that combusts fuel gas, and a heat exchanger 24 that heats the gas flowing through the gas flow path 2 with the combustion heat generated in the combustor 23 to form a high-temperature gas. However, as another means for generating the heating gas, as shown in FIG. 6, there is provided a combustor 23 </ b> A for flowing the high-temperature combustion exhaust gas generated by burning the fuel gas to the gas flow path 2. As shown in FIG. 7, a configuration in which an electric heating mechanism 27 such as a resistance wire or an electric heater is provided outside the gas pipe 4 connected to the gas flow path 2 can be appropriately employed.

  When the former configuration is used, the high-temperature combustion exhaust gas generated in the combustor 23A is used as it is as a heating gas, so that a high-temperature gas can be obtained without using a gas other than electricity or fuel gas. However, since the oxidizing gas flows into the solid oxide fuel cell 10, when the inside is a fuel electrode, it is necessary to pay attention to the oxidation of the fuel electrode, the current collector, and the coating inside the separator.

  On the other hand, when the latter configuration is used, the heating gas may be either an oxidant gas or a fuel gas, and the inside of the solid oxide fuel cell 10 is a fuel electrode, and a reducing gas is introduced. Appropriate when it is desired to raise the temperature.

  FIG. 8 shows another embodiment of the fuel cell stack structure of the present invention. As shown in FIG. 8, this fuel cell stack structure 31 is different from the fuel cell stack structure 31 in the previous embodiment. The difference is that a thermocouple 32 as a temperature sensor disposed at two locations of a central portion 10a having a large heat capacity and a small outer peripheral portion 10b in the solid oxide fuel cell 10 and a monitor 33 connected to the thermocouple 32 are provided. A valve controller (control unit) 34 is provided for operating the valve 21 based on the temperature data detected by the thermocouple 32 displayed on the monitor 33 and adjusting the flow rate of the hot gas G discharged through the short-circuit channel 21. The other structure is the same as the fuel cell stack structure 31 in the previous embodiment.

  In the fuel cell stack structure 31, if the valve controller 34 is operated to close the exhaust side valve 21 when the temperature of the central portion 10 a displayed on the monitor 33 becomes equal to or higher than a certain temperature, The destination is lost and flows into the solid oxide fuel cell 10. As a result, the outer peripheral portion 10b can be heated continuously after the central portion 10a is heated, that is, the entire portion can be rapidly heated, and the temperature distribution at the time of temperature rise becomes uniform.

  Therefore, the temperature increase rate of the outer peripheral portion 10b can be adjusted by the opening degree of the valve 21 on the exhaust side. As for the temperature increase rate of the central portion 10a, if the flow rate of the high temperature gas G flowing in the central gas flow path 2 is excessively high, heat exchange is difficult and the rate is low. In order to adjust the rate of temperature increase, it may be necessary to adjust the gas flow rate on the exhaust side.

  9 and 10 show still another embodiment of the fuel cell stack structure of the present invention. As shown in FIGS. 9 and 10, this fuel cell stack structure 41 is provided when there is no difference in resistance between the flow path to the solid oxide fuel cell 10 and the short-circuit flow path 22, in other words, the solid electrolyte type. This configuration is suitable for use when the amount of hot gas G flowing into the fuel cell 10 increases and it becomes impossible to selectively heat the central portion 10a.

  That is, in the fuel cell stack structure 41, a metal cylinder 42 is provided in close contact with the road wall surface 2 a of the central gas flow path 2, and each gas inlet port of the plurality of solid oxide fuel cells 10 is provided in the metal cylinder 42. The gas inlet 16a is opened and closed by providing a hole 42a at a position corresponding to 16a and rotating up or down, and with such a configuration, even when there is no resistance difference in the flow path, The heating part can be changed.

  FIG. 11 shows a modification of the fuel cell stack structure 41 described above. In this embodiment, one end of a small piece 43 formed by laminating materials having different thermal expansion coefficients is joined in the vicinity of the gas inlet 16a. When the central portion 10a is heated, the gas inlet 16a is opened by deformation due to the difference in thermal expansion of the small piece 43. In this way, it is possible to obtain a shutter function similar to that of the fuel cell stack structure 41 including the metal cylinder 42 described above. Specifically, when a ceramic material such as alumina is formed to a thickness of about 10 μm on a heat-resistant stainless steel having a thickness of about 50 μm, thermal deformation due to a difference in thermal expansion occurs as the temperature rises. It is desirable to use a sputtering method, a CVD method, or a thermal spraying method AD for the ceramic film formation.

  FIG. 12 shows still another embodiment of the fuel cell stack structure of the present invention. As shown in FIG. 12, in this fuel cell stack structure 51, a vertical through hole 14a is formed in the central portion 10a of the solid oxide fuel cell 10, and a heater wire (heating element) 52 is formed in the through hole 14a. To insert.

  In the fuel cell stack structure 51, when power is supplied to the heater wire 52, the central portion 10a is heated and the temperature increase rate is increased. As the heater wire 52, a general heater wire such as Ni—Cr can be used. With this configuration, it is not necessary to install the circulation channel 25 and the like described above, and the system can be simplified. Note that the number of heater wires and the amount of heat generated are determined in consideration of power consumption related to temperature rise.

  Therefore, the temperature change of the central portion and the outer peripheral portion at the start of the fuel cell stack structure 1, 31, 41, 51 described above, and the heater was installed outside and heated at the start of the conventional fuel cell stack structure When the temperature change of the center part and the outer peripheral part at the time was measured, the following results were obtained.

  As shown in FIG. 14, when a heater is placed outside, the heat capacity of the central portion is large, and the radiant heat of the heater is difficult to directly contact, so that the temperature difference between the central portion and the outer peripheral portion during temperature rise is large. On the other hand, as shown in FIG. 13, in the case of the fuel cell stack structures 1, 31, 41, 51 described above, the central portion having a large heat capacity is preferentially heated, so that the central portion is quick. The outer peripheral portion having a small heat capacity is heated to follow the central portion by heat conduction, and the temperature difference between the central portion and the outer peripheral portion during the temperature increase is small.

  Therefore, in the fuel cell stack structure 1, 31, 41, 51 described above, the temperature difference between the large heat capacity portion and the small heat capacity portion can be improved by selectively increasing the temperature rising rate of the large heat capacity portion at the time of startup. It was proved to be small.

It is a whole perspective explanatory view showing one example of a fuel cell stack structure of the present invention. Example 1 FIG. 2 is an exploded perspective view of a solid oxide fuel cell constituting the fuel cell stack structure of FIG. 1. Example 1 FIG. 2 is a cross-sectional explanatory view based on the position of the aa line in FIG. 1 showing a state in which a valve of the fuel cell stack structure in FIG. 1 is opened. Example 1 FIG. 2 is a cross-sectional explanatory view based on the position of the aa line in FIG. 1 showing a state in which the valve of the fuel cell stack structure in FIG. 1 is closed. Example 1 It is piping explanatory drawing which shows the flow path of the heating gas with respect to the fuel cell stack structure of FIG. Example 1 It is piping explanatory drawing which shows the other flow path of the heating gas with respect to the fuel cell stack structure of FIG. FIG. 7 is an explanatory diagram of piping showing still another flow path of heated gas for the fuel cell stack structure of FIG. 1. FIG. 6 is a cross-sectional explanatory view based on the position corresponding to the line aa in FIG. 1 in a state where a valve showing another embodiment of the fuel cell stack structure of the present invention is closed. (Example 2) FIG. 9 is a cross-sectional explanatory view based on the position corresponding to the aa line in FIG. 1 in a state where the gas inlet is closed with a metal cylinder showing still another embodiment of the fuel cell stack structure of the present invention. (Example 3) FIG. 10 is a cross-sectional explanatory view based on the position corresponding to the line aa in FIG. 1 in a state where the gas inlet of the fuel cell stack structure in FIG. 9 is opened. (Example 3) FIG. 7 is a cross-sectional explanatory view based on the position corresponding to the line aa in FIG. 1 in a state where the gas inlet is closed with a small piece showing still another embodiment of the fuel cell stack structure of the present invention. Example 4 FIG. 9 is a cross-sectional explanatory view based on the position corresponding to the line cc of FIG. 1 showing still another embodiment of the fuel cell stack structure of the present invention. (Example 5) It is a graph which shows the temperature change of the center part at the time of starting of the fuel cell stack structure of this invention, and an outer peripheral part. It is a graph which shows the temperature change of the center part and outer periphery part at the time of starting the conventional fuel cell stack structure, installing a heater outside and heating. FIG. 2 is an explanatory cross-sectional view of a fuel cell stack structure that is not preferentially heated based on the position corresponding to the line aa in FIG. FIG. 2 is a cross-sectional explanatory diagram based on a position corresponding to the line bb of FIG. 1 of the fuel cell stack structure that is not preferentially heated.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1, 31, 41, 51 Fuel cell stack structure 2 Gas flow path 2a Road wall surface 4 Gas piping 10 Solid electrolyte fuel cell 10a Central part with large heat capacity 11 Single cell 12 One separator 13 The other separator 16a Gas inlet ( Gas supply port)
21 Exhaust valve (flow path changing means)
22 Short-circuit channel 23, 23A Combustor 24 Heat exchanger 25 Circulation channel 26 Concavity and convexity 27 Heater (electric heating mechanism)
32 Thermocouple (Temperature sensor)
34 Valve controller (control unit)
42 Metal cylinder (opening / closing means)
43 Small pieces (opening and closing means)
52 Heater wire (heating element)
S space

Claims (24)

Two sheet metal separators having a gas introduction hole and a gas discharge hole in the center, and a central flow channel component that introduces and discharges gas to and from the space formed in the center between both separators. And stacking a plurality of solid electrolyte fuel cells each having a single cell of a solid electrolyte type accommodated in a space formed between the separators and having one surface exposed to the outside. These solid electrolyte types supplied to the center of the fuel cell, the gas introduction hole, thereby forming at least one gas flow path to communicate with each other 及 beauty central channel part, a gas into the space of the solid oxide fuel cell from the gas flow path When starting the fuel cell stack structure,
The central part of the solid oxide fuel cell in which the center of each separator and the central flow path part are polymerized is a part with a large heat capacity, while the outer peripheral part of each separator is a part with a small heat capacity,
A method of starting a fuel cell stack structure, wherein a portion having a large heat capacity is selectively heated at a stage of raising the temperature of a plurality of solid oxide fuel cells. The method for starting a fuel cell stack structure according to claim 1, wherein the central flow path component is made of metal . The hot gas to be supplied to the spaces of the solid electrolyte type fuel cell from the gas flow path that discharges through the gas flow, wherein for heating the large parts of the Ah Ru heat capacity in the central portion of the solid oxide fuel cell Item 3. The method for starting the fuel cell stack structure according to Item 1 or 2. The method for starting the fuel cell stack structure according to claim 3, wherein the discharged hot gas is returned to the gas flow path and circulated. The method for starting a fuel cell stack structure according to claim 3 or 4, wherein the flow rate of the hot gas discharged through the gas flow path is controlled based on the temperature of at least one location in the solid oxide fuel cell. As the hot gas for heating to flow into the gas flow path, the start-up of the fuel cell stack structure according to claim 2-5 using heated gas by the heat exchange with the use of combustion heat produced by burning the fuel gas Method. The method for starting a fuel cell stack structure according to claim 2, wherein high-temperature combustion exhaust gas generated by combustion of fuel gas is used as the high-temperature gas for heating that flows through the gas flow path. As the hot gas for heating to flow into the gas channel, the fuel cell stack structure according to claim 2-5 using heated gas by installing electrical heating mechanism in the gas piping coupled to the gas channel starting method. Starting the fuel cell stack structure according to claim 1 is heated by installing a heating element to a large portion of the Ah Ru heat capacity in the central portion of the solid oxide fuel cell. Two sheet metal separators having a gas introduction hole and a gas discharge hole in the center, and a central flow channel component that introduces and discharges gas to and from the space formed in the center between both separators. And stacking a plurality of solid electrolyte fuel cells each having a single cell of a solid electrolyte type accommodated in a space formed between the separators and having one surface exposed to the outside. These solid electrolyte types supplied to the center of the fuel cell, the gas introduction hole, thereby forming at least one gas flow path to communicate with each other 及 beauty central channel part, a gas into the space of the solid oxide fuel cell from the gas flow path In the fuel cell stack structure,
The central part of the solid oxide fuel cell in which the center of each separator and the central flow path part are polymerized is a part with a large heat capacity, while the outer peripheral part of each separator is a part with a small heat capacity,
A fuel cell stack structure characterized in that a portion having a large heat capacity can be selectively heated at the stage of raising the temperature of a plurality of solid oxide fuel cells at the time of startup. The fuel cell stack structure according to claim 10, wherein the central flow path component is made of metal . Circuiting passage to directly discharge the majority of the hot gas to be supplied to the spaces of the solid electrolyte type fuel cell from the gas flow path, each space of the solid oxide fuel cell from the gas flow path to close the short-circuit passage The fuel cell stack structure according to claim 11, further comprising a flow path changing means for returning to a state in which a high temperature gas is supplied to the fuel cell. The fuel cell stack structure according to the hot gas discharged from the short passage to claim 12, and a circulation passage for circulating back into the gas flow path. Adjusting the temperature sensor disposed in at least one place of the solid oxide fuel within cell, the flow rate of the hot gas discharged through the short flow path by operating the flow diversion means based on the temperature detected by the temperature sensor The fuel cell stack structure according to claim 12 or 13, further comprising a control unit. The fuel cell stack structure according to claim 11 to 14 and a closing means for opening and closing the gas supply port for communicating the space of the gas flow path and the solid oxide fuel cell. The fuel cell stack structure according to any one of claims 11 to 15, further comprising: a combustor that combusts fuel gas; and a heat exchanger that heats the gas flowing through the gas flow path with combustion heat generated in the combustor. The fuel cell stack structure according to claim 11 to 15 hot combustion exhaust gas produced by burning fuel gas and a combustor flow to the gas flow path. The fuel cell stack structure according to claim 11 to 15 is provided with an electric heating mechanism for heating the gas flowing in the gas flow path and placed in the gas pipe to bind to said gas flow path. The fuel cell stack structure according to claim 11, wherein unevenness is formed on a road wall surface of the gas flow path. By forming a solid oxide fuel cell central part Oh Ru heat capacity large area other than the portion below 200μm sheet metal of the portion remote from the gas flow path of the solid oxide fuel cell can be heated by thermal conduction The fuel cell stack structure according to claim 10. The fuel cell stack structure according to claim 10, the heating element is provided on a large part of the Ah Ru heat capacity in the central portion of the solid oxide fuel cell. The fuel cell stack structure according to the separator及beauty the gas flow path of the solid oxide fuel cell according to claim 10 to 21 formed by heat resistant alloy material and containing Cr as a main component Ni or Fe. 23. The fuel cell stack structure according to claim 10, wherein a portion having a small heat capacity, which is an outer peripheral portion of the separator of a solid oxide fuel cell , is formed of a rolled thin plate having a thickness of 0.05 to 0.5 mm. 24. The fuel cell stack structure according to claim 10, wherein a solid oxide type single cell is mounted on a portion having a small heat capacity, which is an outer peripheral portion of the separator of a solid oxide fuel cell.

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