JP6848104B2 - Solid oxide fuel cell device - Google Patents

Description

The present invention relates to a solid oxide fuel cell apparatus, and more particularly to a solid oxide fuel cell including a plurality of fuel cell cells that generate electricity from a fuel gas and an oxidant gas.

Solid Oxide Fuel Cell (hereinafter also referred to as "SOFC") uses an oxide ion conductive solid electrolyte as an electrolyte, has electrodes on both sides, and supplies fuel gas to one side. , A fuel cell that operates at a relatively high temperature by supplying an oxidant gas (air, oxygen, etc.) to the other side.

In a solid oxide fuel cell device, off-gas from a fuel cell is burned in a combustion section provided in a module case to generate high-temperature exhaust gas, and steam is generated by heat exchange with the exhaust gas in an evaporator. In the reformer provided in the module case, the raw material gas is reformed with steam by the heat of the exhaust gas to generate fuel gas. Then, the exhaust gas discharged from the reformer is discharged to the outside after the unburned gas such as carbon monoxide is burned in the combustion catalyst.

As a fuel cell device provided with such a catalyst, for example, in Patent Document 1, a fuel cell stack, an evaporator (vaporizer), and a reformer are housed in a fuel cell housing, and platinum. A fuel cell device having a configuration in which a noble metal-based fuel catalyst such as palladium or palladium or a combustion catalyst composed of a base metal-based fuel catalyst such as manganese or iron is provided in the second vaporizer is disclosed. However, although Patent Document 1 may disclose that the inside of the second carburetor having the combustion catalyst is provided outside the fuel cell housing, the specific configuration (shape) of the combustion catalyst and the specific configuration of the combustion catalyst The arrangement is not disclosed.

Further, Patent Document 2 relates to a fuel cell device provided with a catalyst, and is a heat exchanger for exchanging heat between exhaust gas and air provided along the upper surface, side surface, or bottom surface of the storage container. A configuration in which a combustion catalyst is provided in the exhaust gas passage of the above is disclosed.

Japanese Unexamined Patent Publication No. 2014-123576 Japanese Unexamined Patent Publication No. 2013-175448

Here, although the combustion catalyst generates heat, the temperature of the combustion catalyst is about 100 to 500 ° C., which is lower than the operating temperature of 700 ° C. in the module case accommodating the fuel cell and the reformer. Therefore, for example, as described in Patent Document 2, if the combustion catalyst is arranged in the storage container, heat may be taken from the fuel cell or the like. Therefore, the combustion catalyst is installed outside the module case. It is considered to do. Furthermore, in recent years, there has been an increasing need for household fuel cell devices, and miniaturization of fuel cell devices is desired. Therefore, in order to effectively utilize the space in the apparatus, it is conceivable to provide the combustion catalyst in the exhaust gas flow path through which the exhaust gas of the evaporator provided outside the module case flows.

However, when the exhaust gas flow path is filled with a combustion catalyst, the water supplied to the evaporation chamber of the evaporator becomes hot due to the catalytic reaction, and the water supplied to the evaporation chamber is instantly vaporized by the heat of the fuel catalyst. There is a risk that a sudden boiling phenomenon will occur. When such a sudden boiling phenomenon occurs, the pressure in the evaporation chamber suddenly rises, resulting in a state called fuel withering in which fuel gas is no longer supplied to the evaporation chamber.

The present invention has been made in view of the above problems, and an object of the present invention is to enable stable evaporation of water even when a fuel catalyst is arranged in an evaporator. ..

The present invention is a solid oxide type fuel cell device including a fuel cell that generates power by using a fuel gas and an oxidant gas, and comprises a module container, a heat insulating material that covers the periphery of the module container, and a fuel cell. Above the combustion section that burns off-gas from the fuel cell to generate exhaust gas, and above the combustion section inside the module container, it is heated by the exhaust gas to reform the raw material gas and generate fuel gas. The reformer, the exhaust gas flow path through which the exhaust gas discharged from the module container flows, the evaporation chamber that generates water vapor from the water supplied by heat exchange with the exhaust gas flowing through the exhaust gas flow path, and the water vapor and the raw material gas. An evaporator provided outside the module container and inside the heat insulating material, and a combustion catalyst unit that is arranged inside the exhaust gas flow path and oxidizes the unburned fuel contained in the exhaust gas. The exhaust gas flow path is provided above the exhaust gas flow path, and the direction in which the exhaust gas flows through the exhaust gas flow path is opposite to the direction in which the water vapor generated in the evaporation chamber flows. It has a first region on the upstream side and a second region having a height lower than that of the first region on the downstream side, and the combustion catalyst unit is provided in the first region. To do.

According to the present invention having the above configuration, since the combustion catalyst portion is provided in the first region on the upstream side of the exhaust gas flow path of the evaporator, the temperature on the downstream side of the evaporation chamber becomes high due to the reaction heat generated by the catalytic reaction of the combustion catalyst. However, it is possible to prevent the upstream side of the evaporation chamber from becoming excessively hot. As a result, the temperature of the evaporation chamber gradually rises from the downstream side to the upstream side, preventing the water supplied to the evaporation chamber from directly contacting the hot upstream side portion, and gradually releasing the water. It can be heated and stably evaporated.

Further, according to the present invention having the above configuration, since the height of the first region on the upstream side of the exhaust gas flow path is higher than that of the second region on the downstream side, a sufficient amount of combustion catalyst is provided in the combustion catalyst portion. It can be filled, whereby a sufficient exhaust gas purification function can be ensured. Further, the low height of the second region increases the speed of the exhaust gas flowing in the second region, which can improve the heat exchange efficiency between the water and the-exhaust gas.

In the present invention, preferably, the exhaust gas flows in the combustion catalyst portion in the horizontal direction, the combustion catalyst portion includes a protruding space formed by the top surface protruding upward, and the combustion catalyst portion is a protruding space. The region including at least a part is filled with the combustion catalyst.

In the configuration in which the granular combustion catalyst is filled, if vibration from the outside acts on the combustion catalyst during movement or installation, the bulkiness of the combustion catalyst is reduced and a gap is generated above the combustion catalyst portion. In such a case, if the exhaust gas is circulated horizontally through the combustion catalyst section, a part of the exhaust gas is discharged from the combustion catalyst section without passing between the combustion catalysts, so that the purification performance of the exhaust gas deteriorates. It ends up. On the other hand, according to the present invention having the above configuration, even if vibration or the like acts on the combustion catalyst, the bulkiness of the combustion catalyst in the protruding space is reduced, but a gap is generated between the combustion catalyst and the top plate. There is no such thing. This makes it possible to prevent a decrease in the purification efficiency of the combustion catalyst portion due to a decrease in the bulkiness of the combustion catalyst.

In the present invention, the protruding space is preferably configured in a partition wall having a thickness that separates the evaporation chamber and the mixing chamber.
When a protruding space is formed on the top surface so as to project upward, a portion corresponding to the protruding space on the bottom surface of the upper layer protrudes. If such a protrusion on the bottom surface is located in the evaporation chamber or the mixing chamber, the evaporation function in the evaporation chamber is deteriorated and the air flow in the mixing chamber is turbulent. On the other hand, according to the present invention having the above configuration, a protruding space can be formed without affecting the functions of the evaporation chamber and the mixing chamber.

In the present invention, preferably, the evaporator is provided above the module container, a heat insulating material is interposed between the evaporator and the module container, and a heat insulating material is provided between the portion corresponding to the second region of the evaporator and the module container. The thickness of the insulator is larger than the thickness of the heat insulating material between the portion corresponding to the first region of the evaporator and the module container.

As described above, the first region on the upstream side of the exhaust gas flow path becomes relatively high temperature due to the heat of the combustion catalyst, and the second region on the downstream side becomes lower temperature than the upstream side. According to the present invention having the above configuration, since the thickness of the heat insulating material between the portion corresponding to the second region of the evaporator and the module container is thick, the thermal effect on the module container of the second region of the low temperature evaporator is exerted. Can be reduced.

In the present invention, preferably, the heat exchange promoting member is provided in the second region of the exhaust gas flow path, and the heat exchange promoting member is not provided in the first region of the exhaust gas flow path.
In order to efficiently exchange heat between the exhaust gas and water, it is preferable to provide a heat exchange promoting member in the exhaust gas flow path. However, if the heat exchange promoting member is provided in the entire area of the exhaust gas flow path, the combustion catalyst portion cannot be filled with the combustion catalyst. On the other hand, according to the present invention having the above configuration, since the heat exchange promoting member is provided only in the second region, the heat exchange efficiency between the exhaust gas and water can be improved, and the combustion catalyst can be used as the first combustion catalyst. It can be filled in the combustion catalyst part in the region of.

According to the present invention, water can be stably evaporated even when the fuel catalyst is arranged in the evaporator.

It is an overall block diagram which shows the solid oxide fuel cell apparatus (SOFC) by one Embodiment of this invention. It is a side sectional view which shows the fuel cell module of the solid oxide fuel cell apparatus by one Embodiment of this invention. It is sectional drawing along the line III-III of FIG. It is an exploded perspective view of a module case and an air passage cover. It is an enlarged sectional view of the evaporator of the solid electrolyte type fuel cell apparatus shown in FIG. It is a perspective view of the state in which the top plate of the evaporator of the solid electrolyte type fuel cell apparatus shown in FIG. 2 and the combustion catalyst are omitted. It is an enlarged view which shows a part of the continuous groove formed in the bottom surface of the 1st container of the solid oxide fuel cell according to one Embodiment of this invention. (A) is a perspective view showing the plate fins provided in the exhaust gas flow path, and (B) is an enlarged view showing the vicinity of the plate fins in the evaporator. It is a partial cross-sectional view which shows the fuel cell unit of the solid oxide fuel cell according to one Embodiment of this invention. It is a perspective view which shows the fuel cell stack of the solid oxide fuel cell according to one Embodiment of this invention. FIG. 2 is a side sectional view showing a fuel cell module of a solid oxide fuel cell apparatus according to an embodiment of the present invention, similar to FIG. 2. It is sectional drawing along the line III-III of FIG. 2 similar to FIG. It is a perspective view which shows the flow of water vapor and raw material fuel gas in the evaporation chamber and the mixing chamber of the solid oxide fuel cell apparatus by one Embodiment of this invention. It is sectional drawing which enlarges and shows the vicinity of the 1st overlapping part and the 2nd overlapping part of the solid oxide fuel cell apparatus by one Embodiment of this invention. It is a figure which shows the continuous groove formed in the bottom surface of the evaporation chamber by another embodiment.

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

The fuel cell module 2 includes a housing 6, and a metal module container 8 (hereinafter, appropriately referred to as a “module case”) is built in the housing 6 via a heat insulating material 7. In the power generation chamber 10 which is a lower part of the module case 8 which is a closed space, a fuel cell which performs a power generation reaction with a fuel gas and an oxidant gas (hereinafter, appropriately referred to as "air for power generation" or "air") is used. The cell assembly 12 is arranged. The fuel cell assembly 12 includes eight fuel cell stacks 14 (details will be described later in FIG. 11), and the fuel cell stack 14 includes 16 fuel cells, each containing a fuel cell. It is composed of a cell unit 16 (details will be described later in FIG. 12). In this example, the fuel cell assembly 12 has 128 fuel cell units 16. The housing 6 is not essential, and a frame that holds the heat insulating material 7 may be used. In the fuel cell assembly 12, all of the plurality of fuel cell units 16 are connected in series.

A combustion chamber 18 as a combustion unit is formed above the power generation chamber 10 of the module case 8 of the fuel cell module 2. In this combustion chamber 18, residual fuel gas (off gas) and residual fuel gas (off gas) and residuals not used for the power generation reaction are formed. The air is burned to generate exhaust gas (in other words, combustion gas). Further, the module case 8 is covered with the heat insulating material 7 to suppress the heat inside the fuel cell module 2 from being dissipated to the outside air. Further, above the combustion chamber 18, a reformer 120 for reforming the raw material fuel gas (raw material gas) is arranged, and the temperature at which the reformer 120 can be reformed by the combustion heat of the residual gas is reached. It is heating like.

Further, an evaporator 140 is provided in the heat insulating material 7 above the module case 8 in the housing 6. The evaporator 140 evaporates water to generate water vapor by exchanging heat between the supplied water and the exhaust gas, and a mixed gas of the water vapor and the raw fuel gas (hereinafter referred to as "fuel gas"). (Sometimes referred to as) is supplied to the reformer 120 in the module case 8.

Next, the auxiliary machine unit 4 adjusts the flow rate of the water supplied from the pure water tank 26 which stores the water containing the condensed water contained in the exhaust from the fuel cell module 2 and turns it into pure water by a filter. It is equipped with a water flow rate adjusting unit 28 (such as a "water pump" driven by a motor). Further, the auxiliary machine unit 4 adjusts the flow rate of the fuel gas, the gas shutoff valve 32 for shutting off the fuel supplied from the fuel supply source 30 such as city gas, the desulfurizer 36 for removing sulfur from the fuel gas, and the fuel gas flow rate. It is provided with a fuel flow rate adjusting unit 38 (such as a "fuel pump" driven by a motor) and a valve 39 that shuts off the fuel gas flowing out of the fuel flow rate adjusting unit 38 when a power source is lost. Further, the auxiliary machine unit 4 includes an electromagnetic valve 42 that shuts off the air supplied from the air supply source 40, a reforming air flow rate adjusting unit 44 that adjusts the air flow rate, and a power generation air flow rate adjusting unit 45 (with a motor). The driven "air blower" etc.), the first heater 46 that heats the reforming air supplied to the reformer 120, and the second heater 48 that heats the power generation air supplied to the power generation chamber. I have. These first heater 46 and second heater 48 are provided in order to efficiently raise the temperature at the time of start-up, but may be omitted.
In this embodiment, the partial oxidation reforming reaction (POX) and the steam reforming reaction (SR) are carried out from the POX step in which only the partial oxidation reforming reaction (POX) occurs in the reformer 120 when the apparatus is started. It may be configured so that the SR step in which only the steam reforming reaction occurs is performed through the ATR step in which the mixed auto-thermal reforming reaction (ATR) occurs, or the POX step is omitted and the ATR process is changed to the SR process. It may be configured to be migrated, or it may be configured so that only the SR step is performed by omitting the POX step and the ATR step. In the configuration in which only the SR process is performed, the reforming air flow rate adjusting unit 44 is unnecessary.

Next, the hot water production device 50 to which the exhaust gas is supplied is connected to the fuel cell module 2. Tap water is supplied to the hot water production apparatus 50 from the water supply source 24, and the tap water becomes hot water by the heat of the exhaust gas and is supplied to a hot water storage tank of an external water heater (not shown). Further, the fuel cell module 2 is provided with a control box 52 for controlling the supply amount of fuel gas and the like. Further, the fuel cell module 2 is connected to an inverter 54 which is a power extraction unit (power conversion unit) for supplying the electric power generated by the fuel cell module to the outside.

Next, the structure of the fuel cell module of the solid oxide fuel cell device according to the embodiment of the present invention will be described with reference to FIGS. 2 to 4.
FIG. 2 is a side sectional view showing a fuel cell module of a solid oxide fuel cell apparatus according to an embodiment of the present invention, and FIG. 3 is a sectional view taken along the line III-III of FIG. FIG. 4 is an exploded perspective view of the module case and the air passage cover. The housing is omitted in FIGS. 2 and 3.

As shown in FIGS. 2 and 3, the fuel cell module 2 has a fuel cell assembly 12 and a reformer 120 provided inside a module case 8 covered with a heat insulating material 7, and also has a module case 8. It has an evaporator 140 provided outside and inside the heat insulating material 7.

First, as shown in FIG. 4, the module case 8 is composed of a substantially rectangular top plate 8a, a bottom plate 8c, and a pair of opposite side plates 8b connecting the sides extending in the longitudinal direction (left-right direction in FIG. 2). A closing side plate that closes the tubular body and the two opposing openings at both ends of the tubular body in the longitudinal direction, and connects the sides extending in the width direction (left-right direction in FIG. 3) of the top plate 8a and the bottom plate 8c. It consists of 8d and 8e.

In the module case 8, the top plate 8a and the side plate 8b are covered with the air passage cover 160. The air passage cover 160 has a top plate 160a and a pair of side plates 160b facing each other. An opening 167 for passing the exhaust pipe 171 is provided in a substantially central portion of the top plate 160a. Further, an opening 168 to which the air introduction pipe 74 for power generation is connected is provided in the portion of the top plate 160a on the closed side plate 8d side. The top plate 160a and the top plate 8a, and the side plate 160b and the side plate 8b are separated by a predetermined distance. As a result, between the outside of the module case 8 and the heat insulating material 7, specifically, between the top plate 8a and the side plate 8b of the module case 8 and the top plate 160a and the side plate 160b of the air passage cover 160, oxidation occurs. Air passages 161a and 161b are formed as agent gas supply passages (see FIG. 3).

At the lower part of the side plate 8b of the module case 8, a plurality of through holes 8f are provided (see FIG. 4). The power generation air is supplied into the air passage 161a from the power generation air introduction pipe 74 provided in the substantially central portion of the top plate 160a of the air passage cover 160 on the closed side plate 8d side of the module case 8 (FIG. 2). reference). Then, the air for power generation is injected into the power generation chamber 10 from the outlet 8f toward the fuel cell assembly 12 through the air passages 161a and 161b (see FIGS. 3 and 4).

Further, plate fins 162 and 163 as heat exchange promoting members are provided inside the air passages 161a and 161b (see FIG. 3). The plate fins 162 are horizontally provided between the top plate 8a of the module case 8 and the top plate 160a of the air passage cover 160 so as to extend in the longitudinal direction and the width direction, and the plate fins 163 are provided on the side plates 8b of the module case 8. It is provided between the air passage cover 160 and the side plate 160b of the air passage cover 160 and extends in the longitudinal direction and the vertical direction at a position above the fuel cell unit 16.

The power generation air flowing through the air passages 161a and 161b is inside the module case 8 inside the plate fins 162 and 163 (specifically, along the top plate 8a and the side plates 8b) when passing through the plate fins 162 and 163. It will be heated by exchanging heat with the exhaust gas passing through the exhaust passage provided in the above. For this reason, the portions of the air passages 161a and 161b provided with the plate fins 162 and 163 function as heat exchangers (heat exchange portions). The portion provided with the plate fins 162 constitutes the main heat exchanger portion, and the portion provided with the plate fins 163 constitutes the subordinate heat exchanger portion.

Next, the evaporator 140 is fixed so as to extend in the horizontal direction on the top plate 8a of the module case 8. An exhaust pipe 171 and a mixed gas supply pipe 112 are connected to one side end side of the evaporator 140 in the longitudinal direction (left-right direction in FIG. 2), and an exhaust gas discharge pipe 82 is connected to the other end side in the longitudinal direction. Is connected and supported by an exhaust pipe 171. Further, a part of the heat insulating material 7 is arranged between the evaporator 140 and the module case 8 so as to fill these gaps (see FIGS. 2 and 3).

Specifically, the evaporator 140 has a water supply pipe 62 and a water supply pipe 62 that supplies water and raw fuel gas (may include reforming air) to one side end side in the longitudinal direction (left-right direction in FIG. 2). The raw material supply pipe 63 and the exhaust gas discharge pipe 82 (see FIG. 2) for discharging the exhaust gas are connected, and the upper end portion of the exhaust pipe 171 is connected to the other end side in the longitudinal direction. The exhaust pipe 171 penetrates the opening 167 formed in the top plate 160a of the air passage cover 160 and extends downward, and is connected to the exhaust port 111 formed on the top plate 8a of the module case 8. The exhaust port 111 is an opening for discharging the exhaust gas generated in the combustion chamber 18 in the module case 8 to the outside of the module case 8, and is located at a substantially central portion of a top plate 8a having a substantially rectangular top view of the module case 8. It is formed.

FIG. 5 is an enlarged cross-sectional view of the evaporator of the solid electrolyte fuel cell apparatus shown in FIG. Further, FIG. 6 is a perspective view of the solid electrolyte fuel cell apparatus shown in FIG. 2 in a state in which the top plate of the evaporator and the combustion catalyst are omitted. In FIG. 6, the flows of water (steam) and fuel (raw material gas) are shown by solid lines and alternate long and short dash lines, respectively.
The evaporator 140 has a box-shaped evaporator case 141 (FIGS. 2 and 3) which is substantially rectangular in top view. The evaporator case 141 is composed of a first container 143, a second container 144 stacked below the 143 of the first container, and a top plate 142 that closes the upper part of the first container 143. There is.

The top plate 142 is made of a flat metal member. An opening for connecting the raw material supply pipe 63 is formed in the center of one end of the top plate 142 in the width direction, and an opening for connecting the water supply pipe 62 is formed on one side of the one end in the width direction. An opening is formed.

As shown in FIGS. 5 and 6, the first container 143 has a bottom surface 143A1 and 143A2, a side wall 143B extending upward from the outer peripheral edge of the bottom surfaces 143A1 and 143A2, and a brim extending horizontally outward from the upper end of the side wall 143B. A portion 143C and a partition wall 147 are provided.

The bottom surfaces 143A1 and 143A2 of the first container 143 are divided into a first bottom surface 143A1 on the water supply pipe 62 and the raw material supply pipe 63 side and a second bottom surface 143A2 on the mixed gas supply pipe 112 side by the partition wall 147. There is. The first bottom surface 143A1 is the bottom surface of the evaporation chamber 150 as described later, and functions as an evaporation surface for heat exchange between the exhaust gas and the water supplied from the water supply pipe 62. The upper surface of the bottom surface 143A1 of the first container 143 is formed as a rough surface having a surface roughness Ra of 1.5 μm or more. As a result, the bottom surface 143A1 of the first container 143 becomes highly hydrophilic, and the water supplied on the bottom surface 143A1 spreads over a wide range. Further, a continuous groove 156 as a water diffusion means is formed on the upper surface of the bottom surface 143A1 of the first container 143.

FIG. 7 is an enlarged view showing a part of the continuous groove formed on the bottom surface of the first container. The lower part in FIG. 7 is the water supply pipe 62 side. As shown in the figure, square protrusions 156C are provided on the first bottom surface 143A1 of the first container 143 at equal intervals in the front-rear and left-right directions. Further, a cross-shaped protrusion 156D is formed at the center of four square-shaped protrusions 156C adjacent to the front, back, left and right. As a result, the continuous groove 156 has a configuration in which the square grooves 156A are lined up at equal intervals in the front-rear and left-right directions, and the central portions of the opposite sides of the adjacent square grooves 156A are connected by the connecting groove 156B. It has become.

With such a configuration, for example, the water that has entered the continuous groove 156 from the lower center of FIG. 7 is bent and divided to the left and right in the A portion, goes straight in the groove between the A portion and the B portion, and is in the B portion. Bend in. Then, the water bent in the B portion travels straight in the groove between the B portion and the C portion, and is further bent and divided in the C portion. As described above, the water supplied to the continuous groove 156 is bent and divided in the A portion, goes straight in the groove between the A portion and the B portion, is bent in the B portion, and is between the B portion and the C portion. By repeating the straight movement in the groove and the bending and branching in the C portion, the water flows while spreading over a wide area.

An opening is formed in the center of the second bottom surface 143A2 as a discharge port of the mixing chamber 151, and the upper end of the mixing gas supply pipe 112 is connected to this opening. The mixed gas supply pipe 112 is arranged so as to pass through the inside of the exhaust pipe 171. One end thereof is connected to an opening formed in the first container 143, and the other end is the top surface of the reformer 120. It is connected to the mixed gas supply port 120a formed in. The mixed gas supply pipe 112 passes through the exhaust pipe 171 and extends vertically downward into the module case 8, where it is bent by approximately 90 °, extends horizontally along the top plate 8a, and then extends downward by approximately 90 °. It is bent and connected to the reformer 120.

The partition wall 147 extends in the lateral direction between the side walls 143B extending in the longitudinal direction of the first container 143, and is formed by projecting the metal material upward. The partition wall 147 includes a pair of side walls 147B extending in parallel upward from the edges of the first and second bottom surfaces 143A1 and 143A2, and an upper surface 147C connecting between the upper ends of the pair of side wall 147Bs. Further, a recess 147A is formed in the center of the upper portion of the partition wall 147 in the lateral direction (direction in which the partition wall 147 extends).

As shown in FIGS. 5 and 6, the upper surface 147C of the partition wall 147 is formed as a flat surface, and is formed flush with the flange portion 143C. Further, the width of the recess 147A is wider on the first bottom surface 143A1 side than on the second bottom surface 143A2 side, and gradually narrows toward the second bottom surface 143A2 side. Further, the depth of the recess 147A from the upper surface 147C is smaller than the diameter of the alumina balls filled in the evaporation chamber 150, which will be described later. Further, a space 147D is formed inside the partition wall 147 by being surrounded by a pair of side walls 147B and an upper surface 147C, and the space 147D is open downward.

The first container 143 is formed by press-molding a single metal member, and the bottom surfaces 143A1 and 143A2, the side wall 143B, the flange portion 143C, and the partition wall 147 are formed as a continuous integrally molded member. There is.

The first container 143 and the top plate 142 are joined in a state where the lower surface of the top plate 142, the upper surface of the flange portion 143C, and the upper surface 147C of the partition wall 147 are in contact with each other. The evaporation chamber 150 is partitioned by the top plate 142, the first bottom surface 143A1, the side wall 143B, and the partition wall 147 of the first container 143. Further, the mixing chamber 151 is partitioned by the top plate 142, the second bottom surface 143A2 of the first container 143, the side wall 143B, and the partition wall 147. Then, it is partitioned by the recess 147A of the partition wall 147 and the top plate 142, and the evaporation chamber 150 and the mixing chamber 151 are communicated with each other by a communication passage located at the upper part in the center in the width direction of the evaporator 140.

The evaporation chamber 150 is filled with a plurality of granular heat conductive members. As the heat conductive member, for example, a spherical alumina ball or the like can be used. The alumina balls filled in the evaporation chamber 150 are in contact with the top plate 142.

A partition member 152 is arranged in the mixing chamber 151. The partition member 152 is a member made of a heat-resistant metal material having the same cross section and extending in the width direction. The partition member 152 includes an upper surface 152A, a pair of side wall portions 152B extending in parallel downward from both side portions of the upper surface 152A, and a pair of base portions 152C extending outward from the edges of the pair of side wall portions 152B. A horizontally long opening 152D is formed on both sides of the side wall portion 152B on the evaporation chamber 150 side in the width direction.

The length of the partition member 152 in the longitudinal direction is substantially equal to the width of the mixing chamber 151. The partition member 152 is arranged in the evaporation chamber 150 so as to cover the opening (discharge port) to which the mixed gas supply pipe 112 formed on the second bottom surface 143A2 of the first container 143 is connected. In the partition member 152, the first container 143 is formed by spot welding the base 152C and the second bottom surface 143A2 while the lower surface of the base portion 152C is in contact with the second bottom surface 143A2 of the first container 143. It is fixed to. The side portions of the pair of side wall portions 152B of the partition member 152 and the inner wall of the first container 143 are not welded, and a gap is formed. Further, the upper surface 152A of the partition member 152 has a height substantially equal to that of the flange portion 143C of the first container 143.

By providing the partition member 152, the space in the evaporation chamber 150 is a second space between the first space 153A between the partition wall 147 and the partition member 152 and the pair of side wall portions 152B of the partition member 152. It is divided into 153B and a third space 153C between the partition member 152 and the side wall 143B of the first container 143. The first space 153A and the second space 153B communicate with each other through the opening 152D formed in the side wall portion 152B. Further, the third space 153C is connected to the first space 153A and the second space 153B through a gap between both side portions of the pair of side wall portions 152B of the partition member 152 and the inner wall of the first container 143. Communicating. Since the area of this gap is very small compared to the area of the opening 152D formed in the side wall portion 152B, the pressure loss from the first space 153A to the third space 153C is from the first space 153A to the second space 153A. It is higher than the pressure loss up to the space 153B (particularly up to the opening formed in the bottom surface of the second bottom surface 143A2). As will be described later, the second space 153B functions as a mixing flow path for mixing water vapor and the raw material gas, and the third space 153C functions as a bumping buffer space.

The second container 144 has a first bottom surface 144A1 on the side to which the exhaust pipe 171 is connected, a second bottom surface 144A2 on the side to which the exhaust gas discharge pipe 82 is connected, and a first bottom surface 144A1 and a second. An intermediate side wall 144D connecting between the bottom surface 144A2, a side wall 144B extending upward from the outer peripheral edge of the first and second bottom surfaces 144A1 and 144A2, and a flange portion 144C extending horizontally outward from the upper end of the side wall 144B. To be equipped. The first bottom surface 144A1 of the second container 144 is formed with an opening to which the upper end of the exhaust pipe 171 is connected, and the second bottom surface 144A2 is formed with an opening to which the exhaust gas discharge pipe 82 is connected. ing.
The first bottom surface 144A1 extends from an end portion on the side to which the exhaust pipe 171 is connected to a substantially central portion. Further, the second bottom surface 144A2 extends from an end portion on the side to which the exhaust gas discharge pipe 82 is connected to a substantially central portion. The second bottom surface 144A2 is provided at a position higher than that of the first bottom surface 144A1.

The second container 144 is superposed on the first container 143 from below. In the stacked state, the upper surface of the collar portion 144C of the second container 144 is in contact with the lower surface of the collar portion 143C of the first container 143. Further, the upper portion of the side wall 144B of the second container 144 is in contact with the side wall 143B of the first container 143.

Between the bottom surfaces 143A1 and 143A2 of the first container 143 and the first and second bottom surfaces 144A1 and 144A2 of the second container 144, from the exhaust pipe 171 to the exhaust gas discharge pipe 82 in the longitudinal direction of the evaporator 140. An exhaust gas flow path 154 extending to is formed. The exhaust gas flow path 154 communicates with the space 147D in the partition wall 147.

The exhaust gas flow path 154 includes a first region 154A on the side to which the exhaust pipe 171 side is connected (that is, the upstream side) and a second region on the side to which the exhaust gas discharge pipe 82 is connected (that is, the downstream side). Includes 154B and. The first region 154A is an region between the bottom surfaces 143A1 and 143A2 of the first container 143 and the first bottom surface 144A1 of the second container 144. The second region 154B is an region between the first bottom surface 143A1 of the first container 143 and the second bottom surface 144A2 of the second container 144. The height of the first region 154A of the exhaust gas flow path 154 is higher than the height of the second region 154B.

Further, in the first region 154A, a pair of slit members 148A and 148B are provided at positions that sandwich the partition wall 147. Each of the pair of slit members 148A and 148B extends over the entire width of the exhaust gas flow path 154, the lower end is connected to the second bottom surface 144A2 of the second container 144, and the upper end is the first of the first container 143. It is in contact with the bottom surface 143A1 and the second bottom surface 143A2, respectively. Slits through which exhaust gas can pass and the combustion catalyst 149 filled between the slit members 148A and 148B cannot be inserted into the slit members 148A and 148B (that is, the width is narrower than the diameter of the combustion catalyst 149). Is formed.

In the first region 154A of the exhaust gas flow path 154, a combustion catalyst portion 148 surrounded by a first container 143, a second container 144, and a pair of slit members 148A and 148B is formed. The space constituting the combustion catalyst unit 148 includes the space 147D inside the partition wall 147. The space of the combustion catalyst unit 148 is filled with a granular combustion catalyst 149 made of, for example, platinum. The combustion catalyst 149 is filled to a height at which the uppermost portion is located in the space 147D inside the partition wall 147.

A heat insulating material 7 is arranged between the evaporator 140 and the module case 8. As described above, since the second bottom surface 144A2 of the second container 144 is provided at a position higher than the first bottom surface 144A1, the portion corresponding to the second region 154B of the evaporator 140 and the module case 8 The thickness of the heat insulating material 7 between the two is thicker than the thickness of the heat insulating material 7 between the portion of the evaporator 140 corresponding to the first region 154A and the module case 8.

Further, a plate fin 155 as a heat exchange promoting member is provided in the second region 154B of the exhaust gas flow path 154. The plate fins 155 are not provided in the first region 154A. FIG. 8A is a perspective view showing the plate fins provided in the exhaust gas flow path, and FIG. 8B is an enlarged view showing the vicinity of the plate fins in the evaporator.

The plate fin 155 is manufactured by processing a single metal plate. The plate fin 155 has a plate-shaped main body portion 155A, a first protruding portion 155B protruding downward, and a second protruding portion 155C protruding upward.

Further, the first protruding portion 155B is composed of a pair of inclined portions 155B1 extending diagonally downward and a connecting portion 155B2 connecting the lower ends of the pair of inclined portions 155B1. A first passing hole 155B3 is formed at a position above the first protruding portion 155B of the main body portion 155A. Further, a columnar protrusion 155B4 is formed on the lower surface of the connecting portion 155B2 of the first protrusion 155B. The area of the protruding portion 155B4 is smaller than the area of the connecting portions 155B2 and 155C2 of the first and second protruding portions 155B and 155C.

The second protruding portion 155C is composed of a pair of inclined portions 155C1 extending obliquely upward and a connecting portion 155C2 connecting the upper ends of the pair of inclined portions 155C1. A second passing hole 155C3 is formed at a position below the second protruding portion 155C of the main body portion 155A.

In the plate fin 155, the protrusion 155B4 of the first protrusion 155B is in contact with the bottom surface 144A of the second container 144, and the connecting portion 155C2 of the second protrusion 155C is in contact with the bottom surface 143A1 of the first container 143. ing. As a result, the plate fin 155 is thermally connected to the bottom surface 143A1 of the first container 143, and the thermal resistance of the plate fin 155 to the bottom surface 144A of the second container 144 becomes the bottom surface 143A1 of the first container 143. It is larger than the thermal resistance of.

By arranging the plate fins 155 in the exhaust gas flow path 154 in this way, the exhaust gas flow path 154 is divided into an upper space 154C and a lower space 154D by the main body portion 155A of the plate fins 155. Then, the exhaust gas flowing through the exhaust gas flow path 154 flows between the upper space 154C and the lower space 154D through the first passing hole 155B3 and the second passing hole 155C3 formed in the main body portion 155A of the plate fin 155. can do.

Further, the evaporator 140 includes a heater 157. As shown in FIG. 6, it is provided along the outer circumferences of the three sides of the rectangular evaporator 140, and both ends extend toward the evaporation chamber 150 side. As shown in FIG. 5, the heater 157 is laterally in contact with the first overlapping portion 158A in which the side wall 143B of the first container 143 and the side wall 144B of the second container 144 overlap. Further, the heater 157 is in contact with the second overlapping portion 158B on which the flange portion 143C of the first container 143, the flange portion 144C of the second container 144, and the top plate 142 are overlapped with each other from below. The heater 157 may be provided along the entire circumference of the evaporator 140.

As shown in FIG. 5, the water supply pipe 62 and the raw material supply pipe 63 extend horizontally from the right side of FIG. 5 and straddle the side edge of the evaporator 140 on the evaporation chamber 150 side. Then, the water supply pipe 62 and the raw material supply pipe 63 are bent downward, and the opening formed in the top plate 142 is inserted into the evaporation chamber 150 to open into the evaporation chamber 150. The water supply pipe 62 opens in the center in the width direction of the end portion on the evaporation chamber 150 side, and the raw material supply pipe 63 opens on one side in the width direction of the end portion on the evaporation chamber 150 side. There is.

Further, the evaporator 140 includes a temperature sensor 69. Like the water supply pipe 62 and the raw material supply pipe 63, the temperature sensor 69 also extends in the horizontal direction across the side edge of the evaporator 140 on the evaporation chamber 150 side. The temperature sensor 69 is attached so as to abut on the upper surface of the top plate 142. The temperature sensor 69 is arranged so that the sensor unit 69A for detecting the temperature at the tip thereof is located on the downstream side of the middle of the evaporation chamber 150.

In such an evaporator 140, the exhaust gas supplied from the exhaust pipe 171 flows through the exhaust gas flow path 154 and is discharged to the exhaust gas discharge pipe 82. At this time, the exhaust gas comes into contact with the combustion catalyst 149 in the combustion catalyst section 148 in the exhaust gas flow path, so that harmful gas (unburned fuel) such as carbon monoxide contained in the exhaust gas is oxidized. Further, the water supplied from the water supply pipe 62 to the evaporation chamber 150 flows while spreading on the bottom surface 143A1. Then, heat exchange is performed between the exhaust gas and water via the bottom surface 143A1, and the water evaporates to generate water vapor. The water vapor generated in the evaporation chamber 150 flows into the mixing chamber 151 together with the raw material gas supplied from the raw material supply pipe 63, and the water vapor and the fuel gas are mixed and discharged to the mixed gas supply pipe 112. The direction of the exhaust gas flowing through the exhaust gas flow path 154 is opposite to the direction of the flow of water vapor and the raw material gas flowing from the evaporation chamber 150 to the mixing chamber 151.

Next, as shown in FIGS. 2 and 3, the reformer 120 is arranged above the combustion chamber 18 so as to extend horizontally along the longitudinal direction of the module case 8, and the top plate 8a of the module case 8 is arranged. It is fixed to the top plate 8a in a state of being separated by a predetermined distance via an exhaust gas guiding member 130. The reformer 120 has a substantially rectangular outer shape when viewed from above, but is an annular structure in which a through hole 120b is formed in a central portion, and has a housing in which an upper case 121 and a lower case 122 are joined. ing. The through hole 120b is located so as to overlap the exhaust port 111 formed in the top plate 8a in a top view, and preferably the exhaust port 111 is formed at the center position of the through hole 120b.

On one end side (closed side plate 8e side of the module case 8) of the reformer 120 in the longitudinal direction, the mixed gas supply pipe 112 is connected to the mixed gas supply port 120a provided in the upper case 121, and the other end side (the other end side (closed side plate 8e side). On the closed side plate 8d side), the fuel gas supply pipe 64 is connected to the lower case 122, and the hydrogen extraction pipe 65 for the hydrogenated desulfurizer extending to the desulfurizer 36 is connected to the upper case 121. Therefore, the reformer 120 receives the mixed gas (that is, the raw fuel gas mixed with steam (which may include reforming air)) from the mixed gas supply pipe 112, reforms the mixed gas internally, and reforms the mixed gas. It is configured to discharge the reformed gas (that is, the fuel gas) from the fuel gas supply pipe 64 and the hydrogen extraction pipe 65 for the hydrogenated desulfurizer.

The reformer 120 is divided into three spaces by two partition plates 123a and 123b, so that the reformer 120 receives the mixed gas from the mixed gas supply pipe 112 in the reformer 120. A reforming unit 120B filled with a reforming catalyst (not shown) for reforming the mixed gas, and a gas discharge unit 120C for discharging the gas that has passed through the reforming unit 120B are formed. (See FIG. 2). The reforming section 120B is a space sandwiched between the partition plates 123a and 123b, and the reforming catalyst is held in this space. The mixed gas and the reformed fuel gas can move through a plurality of communication holes (slits) provided in the partition plates 123a and 123b. Further, as the reforming catalyst, a catalyst in which nickel is added to the surface of an alumina sphere or a catalyst in which ruthenium is added to the surface of an alumina sphere is appropriately used.

The mixed gas supplied from the evaporator 140 via the mixed gas supply pipe 112 is ejected to the mixed gas receiving unit 120A through the mixed gas supply port 120a. This mixed gas is expanded in the mixed gas receiving section 120A to reduce the ejection speed, passes through the partition plate 123a, and is supplied to the reforming section 120B.
In the reforming section 120B, the mixed gas moving at a low speed is reformed into a fuel gas by the reforming catalyst, and this fuel gas passes through the partition plate 123b and is supplied to the gas discharging section 120C.
In the gas discharge unit 120C, the fuel gas is discharged to the fuel gas supply pipe 64 and the hydrogen extraction pipe 65 for the hydrogenated desulfurizer.

The fuel gas supply pipe 64 as the fuel gas supply passage extends downward along the closing side plate 8d in the module case 8, is bent by approximately 90 ° near the bottom plate 8c, and extends in the horizontal direction, and the fuel cell assembly 12 It enters the manifold 66 formed below the fuel cell 66, and further extends in the manifold 66 in the horizontal direction to the vicinity of the closing side plate 8e on the opposite side. A plurality of fuel supply holes 64b are formed on the lower surface of the horizontal portion 64a of the fuel gas supply pipe 64, and fuel gas is supplied into the manifold 66 from the fuel supply holes 64b. A lower support plate 68 having a through hole for supporting the fuel cell stack 14 is attached above the manifold 66, and the fuel gas in the manifold 66 is supplied into the fuel cell unit 16. To. Further, an ignition device 83 for starting combustion of fuel gas and air is provided in the combustion chamber 18.

The exhaust gas guiding member 130 is arranged between the reformer 120 and the top plate 8a so as to extend horizontally along the longitudinal direction of the module case 8. The exhaust gas guiding member 130 includes a lower guiding plate 131 and an upper guiding plate 132 separated by a predetermined distance in the vertical direction, and connecting plates 133 and 134 to which both ends in the longitudinal direction are attached (FIG. 2). , See Fig. 3). Both ends of the upper guide plate 132 in the width direction are bent downward and connected to the lower guide plate 131. The upper end of the connecting plates 133 and 134 is connected to the top plate 8a, and the lower end is connected to the reformer 120, whereby the exhaust gas guiding member 130 and the reformer 120 are fixed to the top plate 8a. ing.

The lower guide plate 131 is formed with a convex stepped portion 131a in which the central portion in the width direction (left-right direction in FIG. 3) projects downward. On the other hand, in the upper guide plate 132, like the lower guide plate 131, the recess 132a is formed so that the central portion in the width direction is concave downward. The convex step portion 131a and the concave portion 132a extend in the longitudinal direction in parallel in the vertical direction. The mixed gas supply pipe 112 extends horizontally in the recess 132a in the module case 8, then bends downward near the closing side plate 8e, penetrates the upper guide plate 132 and the lower guide plate 131, and penetrates the upper guide plate 132 and the lower guide plate 131. It is connected to the reformer 120.

In the exhaust gas guiding member 130, the gas reservoir 135, which is an internal space that functions as a heat insulating layer, is formed by the upper guiding plate 132, the lower guiding plate 131, and the connecting plates 133, 134. The gas reservoir 135 communicates with the combustion chamber 18 in fluid communication. That is, the upper guide plate 132, the lower guide plate 131, and the connecting plates 133, 134 are connected so as to form a predetermined gap, and are not airtightly connected. Exhaust gas can flow into the gas reservoir 135 from the combustion chamber 18 during operation, and air can flow in from the outside when the gas reservoir 135 is stopped. However, as a whole, gas moves between the inside and outside of the gas reservoir 135. Is gradual.

The upper guide plate 132 is arranged at a predetermined vertical distance from the top plate 8a, and an exhaust extending horizontally along the longitudinal direction and the width direction is provided between the upper guide plate 132 and the top plate 8a. A passage 172 is formed. The exhaust passage 172 is juxtaposed with the air passage 161a with the top plate 8a of the module case 8 interposed therebetween, and in the exhaust passage 172, plate fins similar to the plate fins 162 and 163 in the air passages 161a and 161b. 175 are arranged. The plate fins 175 are provided at substantially the same positions as the plate fins 162 in a top view, and face each other in the vertical direction with the top plate 8a interposed therebetween. Efficient heat exchange is performed between the power generation air flowing through the air passage 161a and the exhaust gas flowing through the exhaust passage 172 in the portion of the air passage 161a and the exhaust passage 172 provided with the plate fins 162 and 175. As a result, the heat of the exhaust gas raises the temperature of the power generation air.

Further, the reformer 120 is arranged at a predetermined horizontal distance from the side plate 8b of the module case 8, and exhaust gas is passed between the reformer 120 and the side plate 8b from the lower side to the upper side. An exhaust passage 173 is formed. Further, the exhaust gas guiding member 130 is also arranged at a predetermined horizontal distance from the side plate 8b, and the exhaust passage 173 extends to the top plate 8a including the passage between the exhaust gas guiding member 130 and the side plate 8b. ing. The exhaust passage 173 communicates with the exhaust passage 172 at an exhaust gas introduction port 172a located at a corner between the top plate 8a and the side plate 8b. The exhaust gas introduction port 172a extends in the longitudinal direction in the module case 8.

Further, the lower guide plate 131 is arranged at a predetermined vertical distance from the top surface of the upper case 121 of the reformer 120, and is located between the lower guide plate 131 and the upper case 121 and the reformer. The through hole 120b of 120 forms an exhaust passage 174 through which the exhaust gas that has passed through the through hole 120b from the lower side to the upper side passes through. The exhaust passage 174 joins the exhaust passage 173 above the reformer 120.

Next, the fuel cell unit 16 will be described with reference to FIG.
FIG. 9 is a partial cross-sectional view showing a fuel cell unit of a solid oxide fuel cell according to an embodiment of the present invention.
As shown in FIG. 9, the fuel cell unit 16 includes a fuel cell 84 and inner electrode terminals 86 which are caps connected to both ends of the fuel cell 84.

The fuel cell 84 is a tubular structure extending in the vertical direction, and has a cylindrical inner electrode layer 90 forming a fuel gas flow path 88 inside, a cylindrical outer electrode layer 92, an inner electrode layer 90, and an outer side. It includes an electrolyte layer 94 between the electrode layer 92 and the electrode layer 92. The inner electrode layer 90 is a fuel electrode through which the fuel gas passes and has a (−) pole, while the outer electrode layer 92 is an air electrode in contact with air and has a (+) pole.

Since the inner electrode terminals 86 attached to the upper end side and the lower end side of the fuel cell 84 have the same structure, the inner electrode terminals 86 attached to the upper end side will be specifically described here. The upper 90a of the inner electrode layer 90 includes an outer peripheral surface 90b and an upper end surface 90c exposed to the electrolyte layer 94 and the outer electrode layer 92. The inner electrode terminal 86 is connected to the outer peripheral surface 90b of the inner electrode layer 90 via a conductive sealing material 96, and further comes into direct contact with the upper end surface 90c of the inner electrode layer 90 to contact the inner electrode layer 90. It is electrically connected. At the center of the inner electrode terminal 86, a fuel gas flow path thin tube 98 communicating with the fuel gas flow path 88 of the inner electrode layer 90 is formed.

The fuel gas flow path thin tube 98 is an elongated thin tube provided so as to extend in the axial direction of the fuel cell 84 from the center of the inner electrode terminal 86. Therefore, a predetermined pressure loss occurs in the flow of fuel gas flowing from the manifold 66 (see FIG. 2) into the fuel gas flow path 88 through the fuel gas flow path thin tube 98 of the lower inner electrode terminal 86. To do. Therefore, the fuel gas flow path thin tube 98 of the lower inner electrode terminal 86 acts as an inflow side flow path resistance portion, and the flow path resistance is set to a predetermined value. Further, a predetermined pressure loss also occurs in the flow of the fuel gas flowing out from the fuel gas flow path 88 through the fuel gas flow path thin tube 98 of the upper inner electrode terminal 86 to the combustion chamber 18 (see FIG. 2). Therefore, the fuel gas flow path thin tube 98 of the upper inner electrode terminal 86 acts as an outflow side flow path resistance portion, and the flow path resistance is set to a predetermined value.

The inner electrode layer 90 is composed of, for example, a mixture of Ni and zirconia doped with at least one selected from rare earth elements such as Ca, Y, and Sc, and Ni and ceria doped with at least one selected from rare earth elements. It is formed from at least one of a mixture, a mixture of Ni and a lantern garade doped with at least one selected from Sr, Mg, Co, Fe and Cu.

The electrolyte layer 94 includes, for example, zirconia doped with at least one selected from rare earth elements such as Y and Sc, ceria doped with at least one selected from rare earth elements, and lanthanum gallate doped with at least one selected from Sr and Mg. Formed from at least one of.

The outer electrode layer 92 is, for example, a lanthanum manganate doped with at least one selected from Sr and Ca, and a lanthanum ferrite doped with at least one selected from Sr, Co, Ni and Cu, Sr, Fe, Ni and Cu. It is formed from at least one of lantern cobaltite, silver, etc. doped with at least one selected from.

Next, the fuel cell stack 14 will be described with reference to FIG.
FIG. 10 is a perspective view showing a fuel cell stack of a solid oxide fuel cell according to an embodiment of the present invention.
As shown in FIG. 10, the fuel cell stack 14 includes 16 fuel cell units 16, and eight of these fuel cell units 16 are arranged side by side in two rows.
Each fuel cell unit 16 is supported by a rectangular lower support plate 68 (see FIG. 2) whose lower end side is made of ceramic, and four fuel cell unit 16s at both ends are supported on the upper end side, which is roughly square. It is supported by the upper support plate 100. The lower support plate 68 and the upper support plate 100 are each formed with through holes through which the inner electrode terminal 86 can pass.

Further, a current collector 102 and an external terminal 104 are attached to the fuel cell unit 16. The current collector 102 includes a fuel electrode connection portion 102a that is electrically connected to an inner electrode terminal 86 attached to an inner electrode layer 90 that is a fuel electrode, and an outer peripheral surface of an outer electrode layer 92 that is an air electrode. It is integrally formed so as to connect the electrically connected air electrode connecting portion 102b. Further, a silver thin film is formed on the entire outer surface of the outer electrode layer 92 (air electrode) of each fuel cell unit 16 as an electrode on the air electrode side. When the air electrode connecting portion 102b comes into contact with the surface of the thin film, the current collector 102 is electrically connected to the entire air electrode.

Further, two external terminals 104 are connected to the air poles of the fuel cell unit 16 located at the end of the fuel cell stack 14 (the back side of the left end in FIG. 6). These external terminals 104 are connected to the inner electrode terminals 86 of the fuel cell unit 16 at the end of the adjacent fuel cell stack 14, and as described above, all of the 128 fuel cell units 16 are connected in series. It is supposed to be done.

Next, with reference to FIGS. 11 and 12, the flow of gas in the fuel cell module of the solid oxide fuel cell apparatus according to the embodiment of the present invention will be described.
FIG. 11 is a side sectional view showing a fuel cell module of a solid oxide fuel cell apparatus according to an embodiment of the present invention similar to FIG. 2, and FIG. 12 is a side sectional view of FIG. 2 III, which is similar to FIG. It is sectional drawing along the −III line. 11 and 12, respectively, are views in which arrows indicating the gas flow are newly added in FIGS. 2 and 3, respectively. In the figure, the solid line arrow indicates the fuel gas flow, the broken line arrow indicates the power generation air flow, and the alternate long and short dash line arrow indicates the exhaust gas flow.

As shown in FIGS. 11 and 12, the water and the raw material gas (raw material gas) are transferred from the water supply pipe 62 and the raw material supply pipe 63 connected to one end side in the longitudinal direction of the evaporator 140 to the upper layer of the evaporator 140. It is supplied into the provided evaporation chamber 150. The water supplied to the evaporation chamber 150 spreads over a wide range because the upper surface of the bottom surface 143A1 of the first container 143 is formed as a rough surface. Further, since the continuous groove 156 is formed on the upper surface of the bottom surface 143A1 of the first container 143, it spreads over a wide range. The water spread over a wide area in this way is heated by the exhaust gas flowing through the exhaust gas flow path 154 provided in the lower layer of the evaporator 140 to become steam. At this time, since the evaporation chamber 150 is filled with alumina balls (heat conductive members), the heat from the exhaust gas flow path 154 is transferred to water via the alumina balls. The water vapor and the raw material fuel gas supplied from the raw material supply pipe 63 flow in the evaporation chamber 150 in the downstream direction.

FIG. 13 is a perspective view showing the flow of water vapor and raw material fuel gas in the evaporation chamber and the mixing chamber. The water vapor and the raw fuel gas generated in the evaporation chamber 150 pass through the recess 147A formed in the center of the partition wall 147 and flow into the mixing chamber 151. At this time, since the width of the recess 147A is narrowed toward the mixing chamber 151, the water vapor and the raw fuel gas are more uniformly mixed when passing through the recess 147A. At this time, since the exhaust gas enters the space 147D inside the partition wall 147, the water vapor and the raw fuel gas are heated by the partition wall 147. Then, the water vapor and the raw fuel gas that have flowed from the recess 147A into the first space 153A of the mixing chamber 151 flow separately on both sides in the width direction. Here, as described above, the pressure loss from the first space 153A to the third space 153C via the partition member 152 and the inner wall of the mixing chamber 151 is the pressure loss of the first space 153A through the opening 152D. Since the pressure loss is higher than the pressure loss from the second bottom surface to the opening formed in the bottom surface of the second bottom surface 143A2, the water vapor and the raw material fuel gas flowing into the first space 153A are shown by a solid line in FIG. As such, it flows into the second space 153B through the opening 152D of the partition member 152. The water vapor and the raw fuel gas are mixed while flowing through the first space 153A and the second space 153B in this way, and are discharged to the mixed gas supply pipe 112.

When a bumping phenomenon occurs in the evaporation chamber 150, water vapor is rapidly generated in the evaporation chamber 150 and flows into the first space 153A. When the sudden boiling phenomenon occurs in this way, the air pressure in the first space 153A of the evaporation chamber 150 and the mixing chamber 151 temporarily increases. When the air pressure in the first space 153A becomes high in this way, the water vapor in the first space 153A passes through the gap between the side portion of the partition member 152 and the inner wall of the first container 143, and the third space 153C. Flow into. As a result, even when a bumping phenomenon occurs, it is possible to suppress a rapid increase in pressure in the evaporation chamber 150 and the mixing chamber 151.

Further, FIG. 14 is an enlarged cross-sectional view showing the vicinity of the first overlapping portion 158A and the second overlapping portion 158B. As shown in the figure, the heater 157 is arranged so as to come into contact with the first overlapping portion 158A and the second overlapping portion 158B of the evaporator 140. Therefore, as shown by the arrows in the figure, heat from the heater 157 is effectively placed on the bottom surface 143A2 of the first container 143 and the second container 144 via the first overlapping portion 158A and the second overlapping portion 158B. The bottom surface 144A and the top plate 142 are heated. As a result, the water vapor and the raw material gas in the evaporation chamber 150 and the mixing chamber 151 are heated. Further, the exhaust gas in the exhaust gas flow path 154 is also heated, and this heat is transferred to the steam and the raw material gas via the bottom surface 143A2 of the first container 143, so that the steam and the raw material gas can be heated more efficiently. Can be done.

The mixed gas (fuel gas) discharged to the mixed gas supply pipe 112 is supplied to the reformer 120 in the module case 8 through the mixed gas supply pipe 112. Since the mixed gas supply pipe 112 passes in the vicinity of the exhaust gas flow path 154, the exhaust pipe 171, and the exhaust passage 172 in order, the mixed gas in the mixed gas supply pipe 112 is caused by the exhaust gas flowing through these passages. Further heated.

The mixed gas flows into the mixed gas receiving section 120A in the reformer 120, passes through the partition plate 123a from here, and flows into the reforming section 120B. The mixed gas is reformed in the reforming section 120B to become a fuel gas. The fuel gas thus generated passes through the partition plate 123b and flows into the gas discharge unit 120C.

Further, the fuel gas branches from the gas discharge unit 120C into the fuel gas supply pipe 64 and the hydrogen extraction pipe 65 for the hydrogenated desulfurizer. Then, the fuel gas that has flowed into the fuel gas supply pipe 64 is supplied into the manifold 66 from the fuel supply hole 64b provided in the horizontal portion 64a of the fuel gas supply pipe 64, and is supplied from the manifold 66 into each fuel cell unit 16. Will be supplied.

Further, as shown in FIGS. 11 and 12, the air for power generation is supplied from the air introduction pipe 74 for power generation to the air passage 161a. The exhaust gas for power generation passes through the exhaust passages 172 and 173 formed in the module case 8 below the plate fins 162 and 163 when passing through the plate fins 162 and 163 in the air passages 161a and 161b. Efficient heat exchange with the gas will result in heating. In particular, since the plate fins 175 are provided in the exhaust passage 172 corresponding to the plate fins 162 of the air passage 161a, the power generation air is exhausted through the plate fins 162 and the plate fins 175. Perform more efficient heat exchange. After that, the power generation air is injected into the power generation chamber 10 from the plurality of outlets 8f provided in the lower part of the side plate 8b of the module case 8 toward the fuel cell assembly 12.

In the present embodiment, since the exhaust passage is not formed in the lateral portion of the fuel cell assembly 12, heat exchange between the power generation air and the exhaust gas is suppressed in this portion. Therefore, in the lateral portion of the fuel cell assembly 12, it is difficult for the temperature gradient in the vertical direction to occur in the power generation air in the air passage 161b.

Further, as shown in FIG. 11, the fuel gas that is not used for power generation in the power generation chamber 10 is burned in the combustion chamber 18 to become exhaust gas (combustion gas), and rises in the module case 8. Specifically, the exhaust gas branches into the exhaust passage 173 and the exhaust passage 174, and is between the outer surface of the reformer 120 and the side plate 8b of the module case 8 and the through hole 120b of the reformer 120. Passes between the reformer 120 and the exhaust gas guiding member 130, respectively. At this time, the exhaust gas passing through the exhaust passage 174 is divided in the width direction by the convex step portion 131a arranged above the through hole 120b of the reformer 120, and does not stay at the lower part of the exhaust gas guiding member 130. It is guided toward the exhaust passage 173 and quickly merges with the exhaust gas flowing through the exhaust passage 173.

After that, the exhaust gas flows into the exhaust passage 172 from the exhaust gas introduction port 172a. In the exhaust passage 172, the exhaust gas flows horizontally through the exhaust passage 172 and flows out from the exhaust port 111 formed in the center of the top plate 8a of the module case 8.

When the exhaust gas flows upward through the exhaust passage 173, heat exchange is performed between the power generation air and the exhaust gas via the plate fins 163 provided in the air passage 161b. Further, when the exhaust gas flows horizontally through the exhaust passage 172, the plate fins 175 provided in the exhaust passage 172 and the plate fins 162 provided in the air passage 161a corresponding to the plate fins 175. Through, efficient heat exchange is performed between the power generation air and the exhaust gas. In this way, the heat of the exhaust gas raises the temperature of the power generation air.

Then, the exhaust gas flowing out from the exhaust port 111 passes through the exhaust pipe 171 provided outside the module case 8 and flows into the exhaust gas flow path 154 of the evaporator 140. The exhaust gas that has flowed into the exhaust gas flow path 154 flows in the exhaust gas flow path 154 toward the exhaust gas discharge pipe 82. The exhaust gas that has flowed into the exhaust gas flow path 154 first passes through the combustion catalyst unit 148 formed in the first region 154A. At this time, when the exhaust gas comes into contact with the combustion catalyst 149 filled in the combustion catalyst section 148, harmful gas (unburned fuel) such as carbon monoxide contained in the exhaust gas is oxidized. Then, the exhaust gas that has passed through the combustion catalyst unit 148 flows into the second region 154B of the exhaust gas flow path 154. Since the height of the second region 154B is lower than that of the first region 154A, the flow velocity of the exhaust gas flowing into the second region 154B increases. The exhaust gas flowing into the second region 154B undergoes heat exchange with the water in the evaporation chamber 150 via the first bottom surface 143A1 of the first container 143. At this time, since the plate fins 155 are provided in the exhaust gas flow path 154, heat exchange between the exhaust gas and the water in the evaporation chamber 150 is performed more efficiently.

Further, the exhaust gas passing through the exhaust gas flow path 154 is heated by the heater 157. Then, the heat transferred to the exhaust gas is transferred to the combustion catalyst 149 when passing through the combustion catalyst unit 148. As a result, the combustion catalyst 149 can be heated to an active state. The heat transferred from the heater 157 is also transferred to the water in the evaporation chamber 150. Then, the exhaust gas that has been heat-exchanged with the water in the evaporation chamber 150 is discharged from the exhaust gas discharge pipe 82.

In the above embodiment, the case where the continuous groove 156 as shown in FIG. 7 is formed on the bottom surface 143A1 of the evaporation chamber 150 has been described, but the pattern of the continuous groove formed on the bottom surface 143A1 of the evaporation chamber 150 is the same. Not limited.

FIG. 17 is a diagram showing a continuous groove 256 formed on the bottom surface 143A1 of the evaporation chamber 150 according to another embodiment. The lower part in FIG. 17 is the water supply pipe 62 side. As shown in the figure, in the present liquid, a regular hexagonal protrusion 256C is provided on the first bottom surface 143A1 of the first container 143. These protrusions 256C are arranged so that their sides of adjacent protrusions 256C face each other in parallel, whereby regular hexagonal grooves are formed in a mesh shape between the protrusions 256C. .. With such a configuration, for example, the water that has entered the groove 256 from the lower center of FIG. 17 is bent and divided to the left and right in the D portion, goes straight in the groove of the E portion, and is bent and divided again in the D portion. To. In this way, the water supplied to the continuous groove 256 flows while spreading over a wide area by repeating bending and splitting in the D portion and straight movement in the groove in the E portion.

As described above, according to each of the above embodiments, the following effects can be obtained.
In the above embodiment, since the combustion catalyst unit 148 is provided in the first region 154A on the upstream side of the exhaust gas flow path 154 of the evaporator 140, the reaction heat generated by the catalytic reaction of the combustion catalyst 149 causes the downstream side of the evaporation chamber 150. However, it is possible to prevent an excessive temperature rise on the upstream side of the evaporation chamber 150. As a result, the temperature of the evaporation chamber 150 gradually rises from the downstream side to the upstream side, preventing the water supplied to the evaporation chamber 150 from coming into contact with the excessively heated portion, and stably. Water can be evaporated.

Further, in the above embodiment, since the first region 154A on the upstream side of the exhaust gas flow path 154 is higher than the second region 154B, the combustion catalyst portion 148 is filled with a sufficient amount of the combustion catalyst 149. This makes it possible to secure a sufficient exhaust gas purification function. Further, since the height of the second region 154B is low, the speed of the exhaust gas flowing in the second region 154B is increased, whereby the heat exchange efficiency between water and the exhaust gas can be improved.

Further, in the above embodiment, the exhaust gas flows horizontally through the combustion catalyst unit 148, the combustion catalyst unit 148 includes a space 147D formed by the top surface protruding upward, and the combustion catalyst unit 148 includes a space 147D. The combustion catalyst 149 is filled until it reaches the protruding space 147D. In the configuration filled with the granular combustion catalyst 149, if vibration from the outside acts on the combustion catalyst during movement or installation, the bulkiness of the combustion catalyst is reduced and a gap is generated above the combustion catalyst portion. .. In such a case, if the exhaust gas is circulated horizontally through the combustion catalyst section, some of the exhaust gas is discharged from the combustion catalyst section without passing between the combustion catalysts, so that the purification performance of the exhaust gas deteriorates. It ends up. On the other hand, according to the above embodiment, even if vibration or the like acts on the combustion catalyst 149, the bulkiness of the combustion catalyst 149 in the protruding space 147D decreases, but between the combustion catalyst 149 and the top plate. There are no gaps. As a result, it is possible to prevent a decrease in the purification efficiency of the combustion catalyst unit 148 due to a decrease in the bulkiness of the combustion catalyst 149.

In the above embodiment, the space 147D above the combustion catalyst unit 148 is configured in a partition wall 147 having a thickness that separates the evaporation chamber 150 and the mixing chamber 151. When a projecting space is formed on the top surface so as to project upward, the portion corresponding to the projecting space of the upper layer protrudes. If such a protrusion is located in the evaporation chamber or the mixing chamber, the evaporation function in the evaporation chamber is deteriorated and the air flow in the mixing chamber is turbulent. On the other hand, according to the above embodiment, the space 147D protruding upward can be formed without affecting the functions of the evaporation chamber 150 and the mixing chamber 151.

Further, as described above, the first region 154A on the upstream side of the exhaust gas flow path 154 becomes relatively high temperature due to the heat of the combustion catalyst 149, and the second region 154B on the downstream side becomes lower temperature than the upstream side. .. On the other hand, according to the above embodiment, since the thickness of the heat insulating material 7 between the portion corresponding to the second region 154B of the evaporator 140 and the module case 8 is thick, the second region of the low temperature evaporator 140 The thermal effect on the module case 8 of 154B can be reduced.

Further, in order to efficiently exchange heat between the exhaust gas and water, it is preferable to provide a heat exchange promoting member such as a plate fin 155 in the exhaust gas flow path 154. However, if the heat exchange promoting member is provided in the entire area of the exhaust gas flow path 154, the combustion catalyst portion 148 cannot be filled with the combustion catalyst 149. On the other hand, in the above embodiment, since the plate fins 155 are provided only in the second region 154B, the heat exchange efficiency between the exhaust gas and water can be improved, and the combustion catalyst 149 is used in the first region 154A. Can be filled in the combustion catalyst section 148 of the above.

1 Solid oxide fuel cell device 2 Fuel cell module 4 Auxiliary unit 6 Housing 7 Insulation material 8 Module case 8 Closed side plate 8a Top plate 8b Side plate 8c Bottom plate 8d Closed side plate 8e Closed side plate 8f Outlet 10 Power generation chamber 12 Fuel cell Assembly 13 Lower guide plate 14 Fuel cell cell stack 16 Fuel cell cell unit 18 Combustion chamber 24 Water supply source 26 Pure water tank 28 Water flow rate adjustment unit 30 Fuel supply source 32 Gas shutoff valve 36 Smelter 38 Fuel flow rate adjustment unit 39 valve 40 Air supply source 42 Electromagnetic valve 44 Air flow adjustment unit for reforming 45 Air flow adjustment unit for power generation 50 Hot water production equipment 52 Control box 54 Inverter 62 Water supply pipe 63 Raw material supply pipe 64 Fuel gas supply pipe 64a Horizontal part 64b Fuel supply Hole 65 Hydrogen desulfurization pipe 66 Manifold 68 Lower support plate 69 Temperature sensor 69A Sensor unit 74 Power generation air introduction pipe 82 Exhaust gas discharge pipe 83 Ignition device 84 Fuel cell cell 86 Inner electrode terminal 88 Fuel gas flow path 90 Inside Electrode layer 90a Upper 90b Outer peripheral surface 90c Upper end surface 92 Outer electrode layer 94 Electrolyte layer 96 Sealing material 98 Fuel gas flow path thin tube 100 Upper support plate 102 Current collector 102a Fuel pole connection 102b Air pole connection 104 External terminal 111 Exhaust port 112 Mixed gas supply pipe 120 Reformer 120A Mixed gas receiving part 120B Reforming part 120C Gas discharging part 120a Mixed gas supply port 120b Through hole 121 Upper case 122 Lower case 123a Partition plate 123b Partition plate 130 Exhaust gas guiding member 131 Lower guide plate 131a Convex step 132 Upper guide plate 132a Recess 133 Connecting plate 135 Gas reservoir 140 Evaporator 141 Evaporator case 142 Top plate 143 First container 143A1 Bottom plate 143A2 Bottom surface 143B Side wall 143C Flange 144 Second container 144A1 First bottom surface 144A2 Second bottom surface 144B Side wall 144C Border 144D Intermediate side wall 147 Partition 147A Recess 147B Side wall 147C Top surface 147D Space 148 Combustion catalyst 148A Slit member 148B Slit member 149 152A Top 152B Side wall 152C Base 152D Opening 153A First space 153B Second space 153C Third space 154 Exhaust gas flow path 1 54A First area 154B Second area 154C Upper space 154D Lower space 155 Plate fin 155A Main body 155B Protruding part 155B1 Inclined part 155B2 Connecting part 155B3 Passing hole 155B4 Protruding part 155C Protruding part 155C1 Inclined part 155C2 Continuous groove 156A Square groove 156B Connection groove 156C Protrusion 156D Protrusion 157 Heater 158A First overlap 158B Second overlap 160 Air passage cover 160a Top plate 160b Side plate 161a Air passage 161b Air passage 162 Plate fin 163 Plate Fin 167 Opening 171 Exhaust pipe 172 Exhaust passage 172a Exhaust gas introduction port 173 Exhaust passage 174 Exhaust passage 175 Plate fin

Claims (5)

A solid oxide fuel cell device equipped with a fuel cell that generates electricity from fuel gas and oxidant gas.
Module container and
The heat insulating material that covers the periphery of the module container and
Above the fuel cell, a combustion unit that burns off-gas from the fuel cell to generate exhaust gas,
A reformer provided above the combustion portion in the module container and heated by the exhaust gas to reform the raw material gas to generate the fuel gas.
An exhaust gas flow path through which the exhaust gas discharged from the module container flows, an evaporation chamber that generates water vapor from water supplied by heat exchange with the exhaust gas flowing through the exhaust gas flow path, and the water vapor and the raw material gas. An evaporator having a mixing chamber for mixing, which is provided outside the module container and inside the heat insulating material, and
It is provided with a combustion catalyst unit that is arranged inside the exhaust gas flow path and oxidizes unburned fuel contained in the exhaust gas.
The evaporation chamber and the mixing chamber are provided above the exhaust gas flow path, and the direction in which the exhaust gas flows through the exhaust gas flow path is opposite to the direction in which the water vapor generated in the evaporation chamber flows.
The exhaust gas flow path has a first region on the upstream side and a second region on the downstream side, which is lower in height than the first region.
The solid oxide fuel cell device, wherein the combustion catalyst unit is provided in the first region. The exhaust gas flows horizontally through the combustion catalyst section, and the exhaust gas is distributed in the horizontal direction.
The combustion catalyst portion includes a protruding space formed by the top surface protruding upward.
The solid oxide fuel cell device according to claim 1, wherein the combustion catalyst unit is filled with a combustion catalyst in a region including at least a part of the protruding space. The solid oxide fuel cell device according to claim 2, wherein the protruding space is formed in a partition wall having a thickness for separating the evaporation chamber and the mixing chamber. The evaporator is provided above the module container and
The heat insulating material is interposed between the evaporator and the module container, and the heat insulating material is interposed.
The thickness of the heat insulating material between the portion of the evaporator corresponding to the second region and the module container is greater than the thickness of the heat insulating material between the portion of the evaporator corresponding to the first region and the module container. The solid oxide fuel cell apparatus according to any one of claims 1 to 3, which is also large. Any of claims 1 to 4, wherein the second region of the exhaust gas flow path is provided with a heat exchange promoting member, and the first region of the exhaust gas flow path is not provided with a heat exchange promoting member. The solid oxide fuel cell apparatus according to item 1.

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