JP6797153B2 - Electrochemical reaction cell stack - Google Patents

Description

The techniques disclosed herein relate to electrochemical reaction cell stacks.

A solid oxide fuel cell (hereinafter referred to as "SOFC") having an electrolyte layer containing a solid oxide is known as one of the types of fuel cells that generate electricity by utilizing an electrochemical reaction between hydrogen and oxygen. Has been done. The fuel cell power generation unit (hereinafter, simply referred to as “power generation unit”), which is a constituent unit of SOFC, is an air that faces each other in a predetermined direction (hereinafter, referred to as “first direction”) with the electrolyte layer in between. It has a fuel cell single cell (hereinafter, simply referred to as “single cell”) including a pole and a fuel pole. SOFCs are generally used in the form of a fuel cell stack composed of a plurality of power generation units arranged side by side in the first direction.

A plurality of manifolds are formed in the fuel cell stack. Each manifold is a gas flow path that extends over multiple units of power generation. In addition, each power generation unit constituting the fuel cell stack includes a fuel chamber facing the fuel electrode, an inlet-side communicating gas flow path that communicates the fuel chamber with one of the plurality of manifolds, and a fuel chamber and the plurality of manifolds. An outlet-side communicating gas flow path that communicates with one is formed. The gas supplied to the manifold (gas containing hydrogen) flows into the fuel chamber of each power generation unit through the inlet side communicating gas flow path in each power generation unit, and is used for the power generation reaction in each power generation unit. After that, the gas in the fuel chamber of each power generation unit is discharged to another manifold through the outlet-side communicating gas flow path in each power generation unit.

Conventionally, a so-called parallel series type fuel cell stack including an upstream power generation unit and a downstream power generation unit is known (see, for example, Patent Document 1). In the parallel series type fuel cell stack, the inlet side communicating gas flow path of the downstream power generation unit communicates with the outlet side communicating gas flow path of the upstream power generation unit via a manifold. Therefore, in the parallel series type fuel cell stack, the gas after being used for the power generation reaction in the upstream power generation unit is supplied to the fuel chamber of the downstream power generation unit and also used for the power generation reaction in the downstream power generation unit. As a result, the fuel gas utilization rate can be improved.

JP-A-2014-197492

In the conventional parallel series type fuel cell stack, the fuel cell stack is compared with the configuration in which the gas discharged from the fuel cell of each power generation unit is discharged to the outside of the fuel cell stack without passing through other power generation units. The pressure loss on the fuel electrode side as a whole may increase.

It should be noted that such a problem is also common to the electrolytic cell stack, which is a form of a solid oxide type electrolytic cell (hereinafter referred to as “SOEC”) that generates hydrogen by utilizing the electrolysis reaction of water. Is. In the present specification, the fuel cell stack and the electrolytic cell stack are collectively referred to as an "electrochemical reaction cell stack". Further, such a problem is common not only to the solid oxide fuel cell but also to other types of electrochemical reaction cell stacks.

This specification discloses a technique capable of solving the above-mentioned problems.

The technique disclosed in the present specification can be realized, for example, in the following forms.

(1) The electrochemical reaction cell stack disclosed in the present specification each has an electrochemical reaction single cell including an electrolyte layer and an air electrode and a fuel electrode facing each other in a first direction with the electrolyte layer interposed therebetween. In an electrochemical reaction cell stack having L (L is an integer of 3 or more) electrochemical reaction units arranged side by side in the first direction, each of the plurality of the electrochemical reaction cell stacks has the same amount of electricity. A plurality of manifolds, which are gas flow paths extending over the chemical reaction units, are formed, and each of the electrochemical reaction units has a fuel chamber facing the fuel electrode, the fuel chamber, and one of the plurality of manifolds. An inlet-side communicating gas flow path and an outlet-side communicating gas flow path that communicate with the fuel chamber and one of the plurality of manifolds are formed, and the L electrochemical reaction units are M (). M is one or more integers) first electrochemical reaction unit and N (N is two or more integers) second electrochemical reaction unit, and each of the second electrochemical reaction units The inlet-side communicating gas flow path communicates with the outlet-side communicating gas flow path of each said first electrochemical reaction unit via at least one of the manifolds, and N second electrochemical reactions. The heights of the portions of each of the second electrochemical reaction units in the fuel chamber facing the fuel electrode in the first direction, including the unit, are equal to each other and each of the first electrochemical reactions. The reaction unit is higher than the height of the portion of the fuel chamber facing the fuel electrode in the first direction, and the N second electrochemical reaction units communicate with the inlet side communication gas flow path and the outlet side communication. The specific communicating gas flow path in the N second electrochemical reaction units, which comprises a plurality of the second electrochemical reaction units having different widths of at least one of the specific communicating gas flow paths with the gas flow path. The maximum value of the width of is smaller than the minimum value of the width of the specific communicating gas flow path in the M first electrochemical reaction units.

In this electrochemical reaction cell stack, M first electrochemical reaction units and N second electrochemical reaction units are provided, and the inlet-side communicating gas flow path of each second electrochemical reaction unit is provided. It communicates with the outlet-side communicating gas flow path of each first electrochemical reaction unit via a manifold. Therefore, the gas discharged from the fuel chamber of each first electrochemical reaction unit is introduced into the fuel chamber of each second electrochemical reaction unit, and then discharged from the fuel chamber of each second electrochemical reaction unit. And finally discharged to the outside of the electrochemical reaction cell stack. Therefore, according to the present electrochemical reaction cell stack, the gas after being used for the reaction in the first electrochemical reaction unit is also used for the reaction in the second electrochemical reaction unit, and is used in the fuel chamber. The utilization rate of the supplied gas can be improved.

However, since this electrochemical reaction cell stack has the above configuration, the gas discharged from the fuel chamber of each electrochemical reaction unit is discharged to the outside of the electrochemical reaction cell stack without passing through other electrochemical reaction units. There is a risk that the pressure loss on the fuel electrode side of the entire electrochemical reaction cell stack will increase as compared to the configuration. However, in the present electrochemical reaction cell stack, the height of the fuel chamber of each second electrochemical reaction unit is higher than the height of the fuel chamber of each first electrochemical reaction unit. Therefore, according to this electrochemical reaction cell stack, it is possible to reduce the pressure loss in the fuel chamber of each second electrochemical reaction unit while improving the utilization rate of the gas supplied to the fuel chamber, and as a result. , It is possible to suppress an increase in pressure loss on the fuel electrode side of the entire electrochemical reaction cell stack.

Further, in the present electrochemical reaction cell stack, since the height of the fuel chamber of each second electrochemical reaction unit is relatively high, the pressure loss in the fuel chamber of each second electrochemical reaction unit can be reduced. On the other hand, the flow rate of the gas supplied to the fuel chamber tends to vary among the plurality of second electrochemical reaction units, and the electrochemical reaction cell is caused by the reaction variation in each second electrochemical reaction unit. The performance of the entire stack may deteriorate. However, in the present electrochemical reaction cell stack, the widths of the specific communicating gas flow paths, which are at least one of the inlet side communicating gas flow path and the outlet side communicating gas flow path, of the N second electrochemical reaction units are mutual. It contains a plurality of different second electrochemical reaction units. Therefore, by appropriately setting the width of the specific communication gas flow path of each second electrochemical reaction unit, it is possible to suppress the variation in the flow rate of the gas supplied to the fuel chamber of each second electrochemical reaction unit. As a result, it is possible to suppress the deterioration of the performance of the entire electrochemical reaction cell stack due to the variation.

(2) In the electrochemical reaction cell stack, the N second electrochemical reaction units are composed of a plurality of the second electrochemical reaction units adjacent to each other in the first direction. A plurality of the second electrochemical reaction units including the unit group and constituting the electrochemical reaction unit group are compared with one said second electrochemical reaction unit and the said one second electrochemical reaction unit. Then, the other second electricity, which is located near the discharge hole for discharging the gas discharged from the fuel chamber to the outside of the electrochemical reaction cell stack and has a narrow width of the specific communication gas flow path. It may be configured to include a chemical reaction unit. Of the plurality of second electrochemical reaction units constituting the electrochemical reaction unit group, the second located relatively close to the discharge hole for discharging the gas discharged from the fuel chamber to the outside of the electrochemical reaction cell stack. In the electrochemical reaction unit of, the flow rate of the gas supplied to the fuel chamber tends to increase. In this electrochemical reaction cell stack, among a plurality of second electrochemical reaction units constituting the electrochemical reaction unit group, in the second electrochemical reaction unit in which the flow rate of the gas supplied to the fuel chamber tends to be large, The width of the specific communication gas flow path is relatively narrow. Therefore, according to the present electrochemical reaction cell stack, it is possible to suppress the variation in the flow rate of the gas supplied to the fuel chamber of the plurality of second electrochemical reaction units constituting the electrochemical reaction unit group, and as a result. , It is possible to effectively suppress the deterioration of the performance of the entire electrochemical reaction cell stack due to the variation.

(3) In the electrochemical reaction cell stack, the N second electrochemical reaction units are each composed of a plurality of the second electrochemical reaction units adjacent to each other in the first direction. Including the electrochemical reaction unit group, the plurality of electrochemical reaction unit groups compare the one electrochemical reaction unit group with the one electrochemical reaction unit group, and the gas discharged from the fuel chamber is compared. It may be configured to include the other electrochemical reaction unit group located near the discharge hole for discharging to the outside of the electrochemical reaction cell stack and having a small minimum width of the specific communicating gas flow path. .. Among the plurality of electrochemical reaction unit groups, the electrochemical reaction unit group located relatively close to the discharge hole for discharging the gas discharged from the fuel chamber to the outside of the electrochemical reaction cell stack is supplied to the fuel chamber. The flow rate of gas tends to increase. In this electrochemical reaction cell stack, among the plurality of electrochemical reaction unit groups, the minimum value of the width of the specific communication gas flow path is compared in the electrochemical reaction unit group in which the flow rate of the gas supplied to the fuel chamber tends to be large. It is getting smaller. Therefore, according to the present electrochemical reaction cell stack, it is possible to suppress the variation in the flow rate of the gas supplied to the fuel chamber of the second electrochemical reaction unit among the plurality of electrochemical reaction unit groups. As a result, it is possible to effectively suppress the deterioration of the performance of the entire electrochemical reaction cell stack due to the variation.

(4) In the electrochemical reaction cell stack, the number N of the second electrochemical reaction units may be smaller than the number M of the first electrochemical reaction units. According to the present electrochemical reaction cell stack, it is possible to improve the utilization rate of the gas supplied to the fuel chamber and suppress the decrease in reactivity due to the shortage of gas in the second electrochemical reaction unit. .. However, in the present electrochemical reaction cell stack, since the number N of the second electrochemical reaction units is smaller than the number M of the first electrochemical reaction units, the second electrochemical reaction unit is compared with the first electrochemical reaction unit. In the chemical reaction unit, the flow rate of the gas supplied to the fuel chamber per electrochemical reaction unit is larger, and the flow rate of the gas supplied to the fuel chamber of each second electrochemical reaction unit varies. It's easy to do. According to this electrochemical reaction cell stack, even in a configuration in which such variation is likely to occur, the width of the specific communicating gas flow path is appropriately set to supply the gas to the fuel chamber of each second electrochemical reaction unit. It is possible to suppress the variation in the flow rate of the gas to be produced, and as a result, it is possible to suppress the deterioration of the performance of the entire electrochemical reaction cell stack due to the variation.

(5) In the electrochemical reaction cell stack, the electrochemical reaction single cell may be configured to be a fuel cell single cell. According to this electrochemical reaction cell stack, it is possible to improve the utilization rate of the gas supplied to the fuel chamber of each electrochemical reaction unit and suppress an increase in the pressure loss of the entire electrochemical reaction cell stack. Further, it is possible to suppress deterioration of the power generation performance of the entire electrochemical reaction cell stack due to the variation in the flow rate of the gas supplied to the fuel chamber of each electrochemical reaction unit.

The techniques disclosed in the present specification can be realized in various forms, for example, in the form of an electrochemical reaction cell stack, a system including an electrochemical reaction cell stack, a method for manufacturing the same, and the like. It is possible to do.

It is a perspective view which shows the appearance structure of the fuel cell stack 100 in this embodiment. It is explanatory drawing which shows the XZ cross-sectional structure of the fuel cell stack 100 at the position of II-II of FIG. It is explanatory drawing which shows the YZ cross-sectional structure of the fuel cell stack 100 at the position of III-III of FIG. It is explanatory drawing which shows the YZ cross-sectional structure of the fuel cell stack 100 at the position IV-IV of FIG. It is explanatory drawing which shows the XZ cross section configuration of two power generation units 102 adjacent to each other at the same position as the cross section shown in FIG. It is explanatory drawing which shows the YZ cross section configuration of two power generation units 102 adjacent to each other at the same position as the cross section shown in FIG. It is explanatory drawing which shows the YZ cross section configuration of two power generation units 102 adjacent to each other at the same position as the cross section shown in FIG. It is explanatory drawing which shows the XY cross-sectional structure of the power generation unit 102 at the position of VIII-VIII of FIG. It is explanatory drawing which shows the XY cross-sectional structure of the power generation unit 102 at the position of IX-IX of FIG. It is explanatory drawing which shows the XY cross-sectional structure of the power generation unit 102 at the position XX of FIG. It is explanatory drawing which shows the width Wi of the combustion chamber inlet side communication gas flow path 142, and the width Wo of the fuel chamber outlet side communication gas flow path 143 in each power generation unit 102 constituting the fuel cell stack 100.

A. First Embodiment:
A-1. Constitution:
(Structure of fuel cell stack 100)
FIG. 1 is a perspective view showing an external configuration of the fuel cell stack 100 according to the present embodiment, and FIG. 2 is a perspective view of the fuel cell stack 100 at the position II-II of FIG. 1 (and FIGS. 8 to 10 described later). It is explanatory drawing which shows the XZ cross-sectional structure, and FIG. 3 is the explanatory view which shows the YZ cross-sectional structure of the fuel cell stack 100 at the position III-III of FIG. 1 (and FIG. 8 to FIG. 10 which will be described later), FIG. Is an explanatory view showing a YZ cross-sectional structure of the fuel cell stack 100 at the position IV-IV in FIG. 1 (and FIGS. 8 to 10 described later). Each figure shows XYZ axes that are orthogonal to each other to identify the direction. In the present specification, for convenience, the Z-axis positive direction is referred to as "upward" and the Z-axis negative direction is referred to as "downward", but the fuel cell stack 100 is actually in such an orientation. It may be installed in a different orientation. The same applies to FIGS. 5 and later. Further, in the present specification, the direction orthogonal to the Z-axis direction is referred to as a plane direction.

The fuel cell stack 100 includes L (L is an integer of 3 or more, L = 15 in this embodiment) fuel cell power generation units (hereinafter, simply referred to as “power generation units”) 102, and a pair of end plates 104. It is equipped with 106. The 15 power generation units 102 are arranged side by side in a predetermined arrangement direction (vertical direction in the present embodiment). The pair of end plates 104 and 106 are arranged so as to sandwich an aggregate composed of 15 power generation units 102 from above and below. The arrangement direction (vertical direction) corresponds to the first direction in the claims.

The 15 power generation units 102 included in the fuel cell stack 100 are M (M is an integer of 1 or more, M = 9 in this embodiment) upstream power generation units 102U and N (N is an integer of 2 or more). In this embodiment, N = 6) downstream power generation units 102D are included. More specifically, of the 15 power generation units 102, the 1st to 3rd, 6th to 8th power generation units 102 counting from the bottom are the downstream power generation unit 102D, and the 4, 5, 9 to 15th power generation units. 102 is the upstream power generation unit 102U. In the present embodiment, the number N of the downstream power generation unit 102D is smaller than the number M of the upstream power generation unit 102U. The upstream power generation unit 102U corresponds to the first electrochemical reaction unit in the claims, and the downstream power generation unit 102D corresponds to the second electrochemical reaction unit in the claims.

A plurality of holes (eight in this embodiment) penetrating in the vertical direction are formed on the peripheral edge of each layer (power generation unit 102, end plates 104, 106) constituting the fuel cell stack 100 in the vertical direction. The holes formed in each layer and corresponding to each other communicate with each other in the vertical direction to form a communication hole 108 extending in the vertical direction from one end plate 104 to the other end plate 106. In the following description, the holes formed in each layer of the fuel cell stack 100 to form the communication holes 108 are also referred to as “communication holes 108”.

A bolt 22 extending in the vertical direction is inserted into each communication hole 108, and the fuel cell stack 100 is fastened by the bolt 22 and the nuts 24 fitted on both sides of the bolt 22. As shown in FIGS. 2 to 4, between the nut 24 fitted on one side (upper side) of the bolt 22 and the upper surface of the end plate 104 forming the upper end of the fuel cell stack 100, and the bolt. An insulating sheet 26 is interposed between the nut 24 fitted on the other side (lower side) of the 22 and the lower surface of the end plate 106 forming the lower end of the fuel cell stack 100. However, in the place where the gas passage member 27 described later is provided, the insulating sheets arranged on the upper side and the lower side of the gas passage member 27 and the gas passage member 27 between the nut 24 and the surface of the end plate 106, respectively. 26 is intervening. The insulating sheet 26 is made of, for example, a mica sheet, a ceramic fiber sheet, a ceramic dust sheet, a glass sheet, a glass-ceramic composite agent, or the like.

The outer diameter of the shaft portion of each bolt 22 is smaller than the inner diameter of each communication hole 108. Therefore, a space is secured between the outer peripheral surface of the shaft portion of each bolt 22 and the inner peripheral surface of each communication hole 108. At least a portion of the space functions as a manifold, which is a gas flow path extending over the plurality of power generation units 102.

Specifically, as shown in FIGS. 1 and 2, one side of the fuel cell stack 100 around the Z-axis direction (the side on the positive side of the X-axis of the two sides parallel to the Y-axis). In the space formed by the bolt 22 (bolt 22A) located near the midpoint and the communication hole 108 into which the bolt 22A is inserted, the oxidant gas OG is introduced from the outside of the fuel cell stack 100 and its oxidation is performed. It functions as an oxidant gas introduction manifold 161 which is a gas flow path for supplying the agent gas OG to each power generation unit 102. Further, the bolt 22 (bolt 22B) located near the midpoint of one side (the side on the negative side of the X-axis of the two sides parallel to the Y-axis) on the outer circumference of the fuel cell stack 100 around the Z-axis direction. And the space formed by the communication hole 108 into which the bolt 22B is inserted discharges the oxidant off-gas OOG, which is the gas discharged from the air chamber 166 of each power generation unit 102, to the outside of the fuel cell stack 100. It functions as an oxidant gas discharge manifold 162. In this embodiment, for example, air is used as the oxidant gas OG.

Further, as shown in FIGS. 1 and 3, the bolt 22 (bolt) located near one apex (the apex on the positive X-axis side and the negative side on the Y-axis) on the outer circumference of the fuel cell stack 100 around the Z-axis direction. In the space formed by the 22C) and the communication hole 108 into which the bolt 22C is inserted, the fuel gas FG is introduced from the outside of the fuel cell stack 100, and the fuel gas FG is supplied to each upstream power generation unit 102U. It functions as a fuel gas introduction manifold 171. Further, as shown in FIGS. 1, 3 and 4, one side of the fuel cell stack 100 around the Z-axis direction (the side on the positive side of the Y-axis of the two sides parallel to the X-axis). The space formed by the bolt 22 (bolt 22D) located near the midpoint and the communication hole 108 into which the bolt 22D is inserted is the gas discharged from the fuel chamber 176 of each upstream power generation unit 102U. It functions as a fuel gas relay manifold 172 that carries the fuel intermediate gas FMG toward each downstream power generation unit 102D. Further, as shown in FIGS. 1, 3 and 4, one side of the fuel cell stack 100 around the Z-axis direction (the side on the negative side of the Y-axis of the two sides parallel to the X-axis). The space formed by the bolt 22 (bolt 22E) located near the midpoint and the communication hole 108 into which the bolt 22E is inserted is the gas discharged from the fuel chamber 176 of each downstream power generation unit 102D. It functions as a fuel gas discharge manifold 173 that discharges the fuel off-gas FOG to the outside of the fuel cell stack 100. In the present embodiment, for example, a hydrogen-rich gas obtained by reforming city gas is used as the fuel gas FG. Further, the fuel intermediate gas FMG contains hydrogen and the like that were not used in the power generation reaction in each upstream power generation unit 102U.

The fuel cell stack 100 is provided with four gas passage members 27. Each gas passage member 27 has a hollow tubular main body 28 and a hollow tubular branch 29 branched from the side surface of the main body 28. The hole of the branch portion 29 communicates with the hole of the main body portion 28. A gas pipe (not shown) is connected to the branch portion 29 of each gas passage member 27. Further, as shown in FIG. 2, the hole of the main body 28 of the gas passage member 27 arranged at the position of the bolt 22A forming the oxidant gas introduction manifold 161 communicates with the oxidant gas introduction manifold 161. That is, the gas passage member 27 functions as a supply hole for supplying the oxidant gas OG from the outside to the inside of the fuel cell stack 100. Further, the hole of the main body 28 of the gas passage member 27 arranged at the position of the bolt 22B forming the oxidant gas discharge manifold 162 communicates with the oxidant gas discharge manifold 162. That is, the gas passage member 27 functions as a discharge hole for discharging the oxidant off-gas OOG from the inside to the outside of the fuel cell stack 100. Further, as shown in FIG. 3, the hole of the main body 28 of the gas passage member 27 arranged at the position of the bolt 22C forming the fuel gas introduction manifold 171 communicates with the fuel gas introduction manifold 171. That is, the gas passage member 27 functions as a supply hole for supplying the fuel gas FG from the outside to the inside of the fuel cell stack 100. Further, as shown in FIG. 4, the hole of the main body 28 of the gas passage member 27 arranged at the position of the bolt 22E forming the fuel gas discharge manifold 173 communicates with the fuel gas discharge manifold 173. That is, the gas passage member 27 functions as a discharge hole for discharging the fuel off-gas FOG from the inside to the outside of the fuel cell stack 100.

(Structure of end plates 104 and 106)
The pair of end plates 104 and 106 are substantially rectangular flat plate-shaped conductive members, and are made of, for example, stainless steel. One end plate 104 is arranged above the power generation unit 102 located at the top, and the other end plate 106 is arranged below the power generation unit 102 located at the bottom. A plurality of power generation units 102 are held in a pressed state by a pair of end plates 104 and 106. The upper end plate 104 functions as a positive output terminal of the fuel cell stack 100, and the lower end plate 106 functions as a negative output terminal of the fuel cell stack 100.

(Structure of power generation unit 102)
FIG. 5 is an explanatory view showing an XZ cross-sectional configuration of two power generation units 102 (one upstream power generation unit 102U and one downstream power generation unit 102D) adjacent to each other at the same position as the cross section shown in FIG. FIG. 6 is an explanatory view showing a YZ cross-sectional configuration of two power generation units 102 (two upstream power generation units 102U) adjacent to each other at the same position as the cross section shown in FIG. 3, and FIG. 7 is shown in FIG. It is explanatory drawing which shows the YZ cross section configuration of two power generation units 102 (two downstream power generation units 102D) adjacent to each other at the same position as the cross section. 8 is an explanatory view showing an XY cross-sectional configuration of the power generation unit 102 (upstream power generation unit 102U) at the position of VIII-VIII of FIG. 5, and FIG. 9 is a power generation at the position of IX-IX of FIG. It is explanatory drawing which shows the XY cross section composition of the unit 102 (upstream power generation unit 102U), and FIG. 10 is the explanation which shows the XY cross section composition of the power generation unit 102 (downstream power generation unit 102D) at the position XX of FIG. It is a figure.

As shown in FIGS. 5 to 7, the power generation unit 102 includes a single cell 110, a separator 120, an air pole side frame 130, an air pole side current collector 134, a fuel pole side frame 140, and a fuel pole side. It includes a current collector 144 and a pair of interconnectors 150 that form the uppermost layer and the lowermost layer of the power generation unit 102. Holes corresponding to the communication holes 108 into which the bolts 22 described above are inserted are formed in the peripheral edges of the separator 120, the air pole side frame 130, the fuel pole side frame 140, and the interconnector 150 around the Z axis direction.

The interconnector 150 is a substantially rectangular flat plate-shaped conductive member, and is made of, for example, ferritic stainless steel. The interconnector 150 ensures electrical continuity between the power generation units 102 and prevents mixing of reaction gases between the power generation units 102. In the present embodiment, when two power generation units 102 are arranged adjacent to each other, one interconnector 150 is shared by two adjacent power generation units 102. That is, the upper interconnector 150 in a certain power generation unit 102 is the same member as the lower interconnector 150 in another power generation unit 102 adjacent to the upper side of the power generation unit 102. Further, since the fuel cell stack 100 includes a pair of end plates 104 and 106, the power generation unit 102 located at the top of the fuel cell stack 100 does not have the upper interconnector 150 and is located at the bottom. The power generation unit 102 does not include the lower interconnector 150 (see FIGS. 2 to 4).

The single cell 110 includes an electrolyte layer 112, an air electrode (cathode) 114 and a fuel electrode (anode) 116 facing each other in the vertical direction (arrangement direction in which the power generation units 102 are arranged) with the electrolyte layer 112 in between. The single cell 110 of the present embodiment is a fuel pole support type single cell in which the fuel pole 116 supports the electrolyte layer 112 and the air pole 114.

The electrolyte layer 112 is a substantially rectangular flat plate-shaped member, and is formed of, for example, a solid oxide such as YSZ (yttria-stabilized zirconia), ScSZ (scandia-stabilized zirconia), and CaSZ (calcia-stabilized zirconia). As described above, the single cell 110 of the present embodiment is a solid oxide fuel cell (SOFC) that uses a solid oxide as an electrolyte. The air electrode 114 is a substantially rectangular flat plate-shaped member, and is formed of, for example, a perovskite-type oxide (for example, LSCF (lanternstrontium cobalt iron oxide), LSM (lanternstrontium manganese oxide), LNF (lantern nickel iron)). Has been done. The fuel electrode 116 is a substantially rectangular flat plate-shaped member, and is formed of, for example, Ni (nickel), a cermet composed of Ni and ceramic particles, a Ni-based alloy, or the like.

The separator 120 is a frame-shaped member in which a substantially rectangular hole 121 penetrating in the vertical direction is formed near the center, and is made of, for example, a metal such as stainless steel. The peripheral portion of the hole 121 in the separator 120 faces the peripheral edge of the surface of the electrolyte layer 112 on the side of the air electrode 114. The separator 120 is bonded to the electrolyte layer 112 (single cell 110) by a bonding portion 124 formed of a brazing material (for example, Ag wax) arranged at the opposite portion thereof. The separator 120 partitions the air chamber 166 facing the single cell 110 and the fuel chamber 176 facing the fuel electrode 116, so that gas leaks from one electrode side to the other electrode side at the peripheral edge of the single cell 110. It is suppressed.

As shown in FIG. 8, the air electrode side frame 130 is a frame-shaped member in which a substantially rectangular hole 131 penetrating in the vertical direction is formed near the center, and is formed of, for example, an insulator such as mica. .. The hole 131 of the air electrode side frame 130 constitutes an air chamber 166 facing the air electrode 114. The air electrode side frame 130 is in contact with the peripheral edge of the surface of the separator 120 opposite to the side facing the electrolyte layer 112 and the peripheral edge of the surface of the interconnector 150 facing the air electrode 114. .. Further, the air electrode side frame 130 electrically insulates between the pair of interconnectors 150 included in the power generation unit 102. Further, in the air electrode side frame 130, the air chamber 166 and the oxidant gas introduction manifold 161 are communicated with each other, and the air chamber inlet side communication gas flow path 132 is communicated with the air chamber 166 and the oxidant gas discharge manifold 162. A communication gas flow path 133 on the chamber outlet side is formed. The air chamber inlet side communicating gas flow path 132 and the air chamber outlet side communicating gas flow path 133 are holes formed in the air electrode side frame 130 in the plane direction.

As shown in FIGS. 9 and 10, the fuel electrode side frame 140 is a frame-shaped member having a substantially rectangular hole 141 formed in the vicinity of the center in the vertical direction, and is formed of, for example, a metal such as stainless steel. ing. Hole 141 of the fuel electrode side frame 140 constitutes a fuel chamber 176 facing the fuel electrode 116. The fuel electrode side frame 140 is in contact with the peripheral edge of the surface of the separator 120 facing the electrolyte layer 112 and the peripheral edge of the surface of the interconnector 150 facing the fuel electrode 116. Further, the fuel electrode side frame 140 has a fuel chamber inlet side communication gas flow path 142 that communicates the fuel chamber 176 and one manifold, and a fuel chamber outlet side communication that communicates the fuel chamber 176 and the other manifold. A gas flow path 143 is formed. The fuel chamber inlet side communicating gas flow path 142 and the fuel chamber outlet side communicating gas flow path 143 are holes extending in the plane direction formed in the fuel electrode side frame 140. As shown in FIG. 9, in the upstream power generation unit 102U, the fuel chamber inlet side communicating gas flow path 142 communicates the fuel chamber 176 and the fuel gas introduction manifold 171, and the fuel chamber outlet side communicating gas flow path 143 is , The fuel chamber 176 and the fuel gas relay manifold 172 are communicated with each other. Further, as shown in FIG. 10, in the downstream power generation unit 102D, the fuel chamber inlet side communicating gas flow path 142 communicates the fuel chamber 176 and the fuel gas relay manifold 172, and the fuel chamber outlet side communicating gas flow path 142. The 143 communicates the fuel chamber 176 and the fuel gas discharge manifold 173.

The air pole side current collector 134 is arranged in the air chamber 166 as shown in FIGS. 5 to 8. The air electrode side current collector 134 is composed of a plurality of substantially square columnar conductive members arranged at predetermined intervals, and is made of, for example, ferritic stainless steel. The air electrode side current collector 134 is in contact with the surface of the air electrode 114 opposite to the side facing the electrolyte layer 112 and the surface of the interconnector 150 on the side facing the air electrode 114. However, as described above, since the power generation unit 102 located at the top of the fuel cell stack 100 does not have the upper interconnector 150, the air electrode side current collector 134 in the power generation unit 102 has an upper end plate. It is in contact with 104. Since the air electrode side current collector 134 has such a configuration, the air electrode 114 and the interconnector 150 (or the end plate 104) are electrically connected. The air electrode side current collector 134 and the interconnector 150 may be formed as an integral member.

The fuel electrode side current collector 144 is arranged in the fuel chamber 176 as shown in FIGS. 5 to 7, 9 and 10. The fuel electrode side current collector 144 is a conductor including an interconnector facing portion 146, a plurality of electrode facing portions 145, and a connecting portion 147 connecting each electrode facing portion 145 and the interconnector facing portion 146. For example, it is made of nickel, nickel alloy, stainless steel, or the like. Each electrode facing portion 145 is in contact with the surface of the fuel pole 116 opposite to the side facing the electrolyte layer 112, and the interconnector facing portion 146 is the surface of the interconnector 150 facing the fuel pole 116. Is in contact with. However, as described above, since the power generation unit 102 located at the bottom of the fuel cell stack 100 does not have the lower interconnector 150, the interconnector facing portion 146 in the power generation unit 102 is the lower end plate. It is in contact with 106. Since the fuel pole side current collector 144 has such a configuration, the fuel pole 116 and the interconnector 150 (or the end plate 106) are electrically connected to each other. A spacer 149 formed of, for example, mica is arranged between the electrode facing portion 145 and the interconnector facing portion 146. Therefore, the fuel electrode side current collector 144 follows the deformation of the power generation unit 102 due to the temperature cycle and the reaction gas pressure fluctuation, and the fuel electrode 116 and the interconnector 150 (or the end plate 106) via the fuel electrode side current collector 144 follow. Good electrical connection with is maintained.

A-2. Operation of fuel cell stack 100:
As shown in FIGS. 2 and 5, the outside of the fuel cell stack 100 is provided via a gas pipe (not shown) connected to a branch portion 29 of the gas passage member 27 provided at the position of the oxidant gas introduction manifold 161. When the oxidant gas OG is supplied from, the oxidant gas OG is supplied to the oxidant gas introduction manifold 161 through the holes of the branch portion 29 and the main body portion 28 of the gas passage member 27, and the oxidant gas introduction manifold 161 Is supplied to the air chamber 166 via the air chamber inlet side communicating gas flow path 132 of each power generation unit 102 (upstream power generation unit 102U and downstream power generation unit 102D), and the air electrode 114 of the single cell 110 of each power generation unit 102. Is supplied to.

Further, as shown in FIGS. 3 and 6, the fuel cell stack 100 is connected to a gas pipe (not shown) connected to a branch portion 29 of the gas passage member 27 provided at the position of the fuel gas introduction manifold 171. When the fuel gas FG is supplied from the outside, the fuel gas FG is supplied to the fuel gas introduction manifold 171 through the holes of the branch portion 29 and the main body portion 28 of the gas passage member 27, and each upstream from the fuel gas introduction manifold 171. It is supplied to the fuel chamber 176 via the fuel chamber inlet side communicating gas flow path 142 of the side power generation unit 102U, and is supplied to the fuel pole 116 of the single cell 110 of each upstream power generation unit 102U. The fuel gas introduction manifold 171 does not communicate with the fuel chamber 176 of each downstream power generation unit 102D, and the fuel gas FG is supplied from the fuel gas introduction manifold 171 to the fuel chamber 176 of each downstream power generation unit 102D. There is nothing.

Further, as shown in FIGS. 3, 4, 6 and 7, the fuel was discharged from the fuel chamber 176 of each upstream power generation unit 102U to the fuel gas relay manifold 172 via the fuel chamber outlet side communicating gas flow path 143. The fuel intermediate gas FMG is supplied to the fuel chamber 176 via the fuel chamber inlet side communicating gas flow path 142 of each downstream power generation unit 102D, and is supplied to the fuel pole 116 of the single cell 110 of each downstream power generation unit 102D. ..

Oxidizing agent gas OG is supplied to the air pole 114 of the single cell 110 of each power generation unit 102 (upstream power generation unit 102U and downstream power generation unit 102D), and fuel gas FG or fuel intermediate gas FMG is supplied to the fuel pole 116 of the single cell 110. Is supplied, power is generated in each single cell 110 by an electrochemical reaction of the oxidant gas OG and the fuel gas FG or the fuel intermediate gas FMG. This power generation reaction is an exothermic reaction. In each power generation unit 102, the air pole 114 of the single cell 110 is electrically connected to one of the interconnectors 150 via the air pole side current collector 134, and the fuel pole 116 is via the fuel pole side current collector 144. It is electrically connected to the other interconnector 150. Further, the plurality of power generation units 102 included in the fuel cell stack 100 are electrically connected in series. Therefore, the electric energy generated in each power generation unit 102 is taken out from the end plates 104 and 106 that function as the output terminals of the fuel cell stack 100. Since the SOFC generates electricity at a relatively high temperature (for example, 700 ° C. to 1000 ° C.), the fuel cell stack 100 is a heater (for example, until the high temperature can be maintained by the heat generated by the power generation after the start-up. (Not shown) may be heated.

As shown in FIGS. 2 and 5, the oxidizer gas discharge manifold 162 is transmitted from the air chamber 166 of each power generation unit 102 (upstream power generation unit 102U and downstream power generation unit 102D) to the air chamber outlet side communication gas flow path 133. The oxidant off-gas OOG discharged to the gas pipe (gas pipe) connected to the branch portion 29 through the holes of the main body portion 28 and the branch portion 29 of the gas passage member 27 provided at the position of the oxidant gas discharge manifold 162. It is discharged to the outside of the fuel cell stack 100 via (not shown). Further, as shown in FIGS. 4 and 7, the fuel off-gas FOG discharged from the fuel chamber 176 of each downstream power generation unit 102D to the fuel gas discharge manifold 173 via the fuel chamber outlet side communication gas flow path 143 is the fuel. The outside of the fuel cell stack 100 via the holes of the main body 28 and the branch 29 of the gas passage member 27 provided at the position of the gas discharge manifold 173, and via a gas pipe (not shown) connected to the branch 29. Is discharged to.

As described above, in the fuel cell stack 100 of the present embodiment, the fuel gas FG introduced from the outside of the fuel cell stack 100 is supplied in parallel to the plurality of upstream power generation units 102U via the fuel gas introduction manifold 171. After that, the fuel intermediate gas FMG discharged from each upstream power generation unit 102U is supplied in parallel to the plurality of downstream power generation units 102D via the fuel gas relay manifold 172. That is, the fuel cell stack 100 of the present embodiment is a so-called parallel series type fuel cell stack.

A-3. Detailed configuration on the fuel pole side of each power generation unit 102:
Next, the configuration on the fuel electrode side of each power generation unit 102 will be described in more detail. As described above, the L (L = 15 in this embodiment) power generation units 102 included in the fuel cell stack 100 of the present embodiment are replaced with M (M = 9 in this embodiment) upstream power generation units 102U. , N (N = 6 in this embodiment) of downstream power generation units 102D. In the fuel cell stack 100 of the present embodiment, the number N of the downstream power generation unit 102D is smaller than the number M of the upstream power generation unit 102U (N <M).

In the fuel cell stack 100 of the present embodiment, the height Hd of the portion of each of the six downstream power generation units 102D facing the fuel pole 116 in the Z-axis direction (hereinafter, simply "downstream power generation unit"). The height Hd of the fuel chamber 176 of 102D ”is equal to each other (see FIGS. 5 and 7). If the height Hd of the fuel chamber 176 of the downstream power generation unit 102D is different at each position in the plane direction in the fuel chamber 176, the height Hd of the fuel chamber 176 of the downstream power generation unit 102D is at each position. It shall mean the minimum value of the height Hd of. Further, in the present specification, when the heights of the plurality of fuel chambers 176 are equal to each other, it means that the difference in height of each fuel chamber 176 is ± 0.01 mm or less. The height Hd of the fuel chamber 176 of each downstream power generation unit 102D is, for example, about 1.9 mm to 2.3 mm.

Similarly, in the fuel cell stack 100 of the present embodiment, the height Hu of the portion of each fuel chamber 176 of the nine upstream power generation units 102U facing the fuel pole 116 in the Z-axis direction (hereinafter, simply "upstream"). The height Hu of the fuel chamber 176 of the side power generation unit 102U) is equal to each other (see FIGS. 5 and 6). If the height Hu of the fuel chamber 176 of the upstream power generation unit 102U is different at each position in the plane direction in the fuel chamber 176, the height Hu of the fuel chamber 176 of the upstream power generation unit 102U is at each position. It shall mean the minimum value of the height Hu of. The height Hu of the fuel chamber 176 of each upstream power generation unit 102U is, for example, about 1.4 mm to 1.8 mm.

Further, in the fuel cell stack 100 of the present embodiment, the height Hd of the fuel chamber 176 of each downstream power generation unit 102D is higher than the height Hu of the fuel chamber 176 of each upstream power generation unit 102U (Hd> Hu). In the present embodiment, the thickness (size in the Z-axis direction) of the fuel pole side frame 140 of each downstream power generation unit 102D is made thicker than the thickness of the fuel pole side frame 140 of each upstream power generation unit 102U. The relationship (Hd> Hu) is realized. The difference (= Hd-Hu) between the height Hd of the fuel chamber 176 of the downstream power generation unit 102D and the height Hu of the fuel chamber 176 of the upstream power generation unit 102U is preferably 0.5 mm or more.

Further, FIG. 11 is an explanatory diagram showing the width Wi of the fuel chamber inlet side communicating gas flow path 142 and the width Wo of the fuel chamber outlet side communicating gas flow path 143 in each power generation unit 102 constituting the fuel cell stack 100. In the table at the right end of FIG. 11, the values of the width Wi of the fuel chamber inlet side communicating gas flow path 142 and the width Wo of the fuel chamber outlet side communicating gas flow path 143 are shown for each power generation unit 102 constituting the fuel cell stack 100. It is shown.

Here, as shown in FIGS. 9 and 10, the width Wi of the fuel chamber inlet side communicating gas flow path 142 in each power generation unit 102 is the extending direction of the fuel chamber inlet side communicating gas flow path 142 in the Z-axis direction. It is the size in the direction orthogonal to. When the width Wi is different at each position of the fuel chamber inlet side communicating gas flow path 142, the width Wi is specified at the connection position with the fuel chamber 176 in the fuel chamber inlet side communicating gas flow path 142. When a plurality of fuel chamber inlet-side communicating gas flow paths 142 exist in one power generation unit 102, the total width Wi of each fuel chamber inlet-side communicating gas flow path 142 is calculated as the fuel chamber of the power generation unit 102. It is assumed that the width Wi of the inlet side communicating gas flow path 142. Similarly, the width Wo of the combustion chamber outlet side communicating gas flow path 143 in each power generation unit 102 is the size in the direction orthogonal to the extending direction of the fuel chamber outlet side communicating gas flow path 143 in the Z-axis direction. When the width Wo is different at each position of the fuel chamber outlet side communicating gas flow path 143, the width Wo shall be specified at the connection position with the fuel chamber 176 in the fuel chamber outlet side communicating gas flow path 143. When a plurality of fuel chamber outlet side communicating gas flow paths 143 exist in one power generation unit 102, the total width Wo of each fuel chamber outlet side communicating gas flow path 143 is calculated as the fuel chamber of the power generation unit 102. The width W of the outlet-side communicating gas flow path 143.

As shown in FIG. 11, in the fuel cell stack 100 of the present embodiment, the width Wi of the fuel chamber inlet side communicating gas flow path 142 in each of the six downstream power generation units 102D is not equal to each other. That is, the six downstream power generation units 102D include a plurality of downstream power generation units 102D having different width Wis of the fuel chamber inlet side communication gas flow paths 142. In the present specification, the fact that the width Wis of the combustion chamber inlet side communicating gas flow paths 142 are different from each other means that the difference between the width Wis is larger than ± 0.01 mm. Specifically, in the fuel cell stack 100 of the present embodiment, the width Wi of the fuel cell inlet side communicating gas flow path 142 of the 1, 2, 3, 6, 7, and 8th downstream power generation unit 102D counted from the bottom. Are "j" mm, "j + 0.1" mm, "j + 0.2" mm, "j + 0.1" mm, "j + 0.2" mm, and "j + 0.3" mm, respectively. Here, "j" is a reference value of the width Wi of the combustion chamber inlet side communicating gas flow path 142 (hereinafter, referred to as "inlet side reference width j"), and in the present embodiment, the power generation unit located at the lowest position. It is the same value as the width Wi of the communication gas flow path 142 on the inlet side of the fuel chamber of 102 (downstream power generation unit 102D). The reference width j on the inlet side is, for example, about 1.2 mm to 1.6 mm. Further, in the fuel cell stack 100 of the present embodiment, in each downstream power generation unit 102D, the width Wi of the fuel chamber inlet side communicating gas flow path 142 is smaller than the height Hd of the fuel chamber 176. The ratio (= Hd / Wi) of the height Hd of the fuel chamber 176 to the width Wi of the communication gas flow path 142 on the fuel chamber inlet side is preferably 1.1 or more.

Similarly, in the fuel cell stack 100 of the present embodiment, the widths of the fuel chamber outlet side communicating gas flow paths 143 in each of the six downstream power generation units 102D are not equal to each other. That is, the six downstream power generation units 102D include a plurality of downstream power generation units 102D having different widths Wo of the fuel chamber outlet side communication gas flow path 143. In the present specification, the fact that the widths Wo of the fuel chamber outlet side communicating gas flow paths 143 are different from each other means that the difference between the widths Wo is larger than ± 0.01 mm. Specifically, in the fuel cell stack 100 of the present embodiment, the width Wo of the fuel cell outlet side communication gas flow path 143 of the 1, 2, 3, 6, 7, and 8th downstream power generation unit 102D counted from the bottom. Are "k" mm, "k + 0.1" mm, "k + 0.2" mm, "k + 0.1" mm, "k + 0.2" mm, and "k + 0.3" mm, respectively. Here, "k" is a reference value of the width Wo of the combustion chamber outlet side communication gas flow path 143 (hereinafter, referred to as "outlet side reference width k"), and in the present embodiment, the power generation unit located at the lowest position. It is the same value as the width Wo of the fuel chamber outlet side communication gas flow path 143 of 102 (downstream power generation unit 102D). The outlet side reference width k is, for example, about 1.2 mm to 1.6 mm. Further, in the fuel cell stack 100 of the present embodiment, in each downstream power generation unit 102D, the width Wo of the fuel chamber outlet side communicating gas flow path 143 is smaller than the height Hd of the fuel chamber 176. The ratio of the height Hd of the fuel chamber 176 to the width Wo of the gas flow path 143 on the outlet side of the fuel chamber (= Hd / Wo) is preferably 1.1 or more.

On the other hand, in the fuel cell stack 100 of the present embodiment, the width Wi of the fuel chamber inlet side communicating gas flow path 142 in each of the nine upstream power generation units 102U is equal to each other (all are "j + 0.5" mm). ). Further, the widths of the fuel chamber outlet-side communicating gas flow paths 143 in each of the nine upstream power generation units 102U are also equal to each other (all are "k + 0.5" mm).

Further, in the fuel cell stack 100 of the present embodiment, the maximum value (= "j + 0.3" mm) of the width Wi of the fuel chamber inlet side communicating gas flow path 142 in the six downstream power generation units 102D is nine. It is smaller than the minimum value (= "j + 0.5" mm) of the width Wi of the fuel chamber inlet side communicating gas flow path 142 in the upstream power generation unit 102U. That is, the width Wi of the combustion chamber inlet side communicating gas flow path 142 in each downstream power generation unit 102D is generally wider than the width Wi of the fuel chamber inlet side communicating gas flow path 142 in each upstream power generation unit 102U. It's getting narrower. Similarly, in the fuel cell stack 100 of the present embodiment, the maximum value (= “k + 0.3” mm) of the width Wo of the fuel chamber outlet side communicating gas flow path 143 in the six downstream power generation units 102D is nine. It is smaller than the minimum value (= "k + 0.5" mm) of the width Wo of the fuel chamber outlet side communicating gas flow path 143 in the upstream side power generation unit 102U. That is, the width Wo of the combustion chamber outlet side communicating gas flow path 143 in each downstream power generation unit 102D is generally wider than the width Wo of the fuel chamber outlet side communicating gas flow path 143 in each upstream power generation unit 102U. It's getting narrower.

The fuel chamber inlet side communicating gas flow path 142 and the fuel chamber outlet side communicating gas flow path 143 in the present embodiment correspond to the specific communicating gas flow path within the scope of the claims.

Further, assuming that a group composed of a plurality of downstream power generation units 102D adjacent to each other in the Z-axis direction is referred to as a downstream power generation unit group 102DG, the fuel cell stack 100 of the present embodiment has six downstream power generation units 102D. It can be said that the power generation unit 102D has two downstream power generation unit groups 102DG (see FIGS. 2 to 4 and 11). That is, in the present embodiment, the downstream power generation unit group 102DG composed of the first, second, and third downstream power generation units 102D counted from the bottom (hereinafter, referred to as "lower downstream power generation unit group 102DG1"). And, there is a downstream power generation unit group 102DG (hereinafter, referred to as “upper downstream power generation unit group 102DG2”) composed of three downstream power generation units 102D, which are the sixth, seventh, and eighth from the bottom.

Focusing on one downstream power generation unit group 102DG, among the plurality of downstream power generation units 102D constituting the downstream power generation unit group 102DG, the downstream power generation unit 102D located on the lower side communicates with the combustion chamber inlet side. The width Wi of the gas flow path 142 and the width Wo of the communication gas flow path 143 on the fuel chamber outlet side are narrowed. For example, among the three downstream power generation units 102D constituting the lower downstream power generation unit group 102DG1, the width Wi of the fuel chamber inlet side communicating gas flow path 142 in the downstream power generation unit 102D located at the uppermost side is "j + 0. The width Wi of the fuel chamber inlet side communicating gas flow path 142 in the downstream power generation unit 102D, which is 2 ”mm and is located at the lowermost side, is“ j ”mm, which is narrower than that, and is located on the downstream side between the two. The width Wi of the communication gas flow path 142 on the fuel chamber inlet side in the power generation unit 102D is "j + 0.1" mm, which is intermediate between the two. The width Wo of the combustion chamber outlet side communication gas flow path 143 in the lower downstream power generation unit group 102DG1, the width Wi of the fuel chamber inlet side communication gas flow path 142 of the upper downstream power generation unit group 102DG2, and the fuel chamber outlet side communication gas. The same applies to the width Wo of the flow path 143.

Of the plurality of downstream power generation units 102D constituting one downstream power generation unit group 102DG, the downstream power generation unit 102D located on the lower side uses the gas (fuel off gas FOG) discharged from the fuel chamber 176. It can be said that the downstream power generation unit 102D is located closer to the discharge hole (that is, the gas passage member 27 (see FIG. 4) provided at the position of the fuel gas discharge manifold 173) for discharging to the outside of the fuel cell stack 100. .. Therefore, in the fuel cell stack 100 of the present embodiment, the plurality of downstream power generation units 102D constituting one downstream power generation unit group 102DG include one downstream power generation unit 102D and the one downstream power generation unit 102D. In comparison, it is located near the discharge hole for discharging the gas discharged from the fuel cell stack 100 to the outside of the fuel cell stack 100, and the width Wi of the fuel cell inlet side communication gas flow path 142 and the fuel cell outlet side communication. It can be said that the gas flow path 143 includes another downstream power generation unit 102D having a narrow width Wo.

Comparing a plurality of downstream power generation unit groups 102DG with each other, the downstream power generation unit group 102DG located on the lower side has the minimum value of the width Wi of the fuel chamber inlet side communication gas flow path 142 and the fuel chamber outlet side communication. The minimum value of the width Wo of the gas flow path 143 is small. For example, the minimum value (= "j" mm) of the width Wi of the fuel chamber inlet side communicating gas flow path 142 in the lower downstream power generation unit group 102DG1 is the fuel chamber inlet side communicating gas flow in the upper downstream power generation unit group 102DG2. It is smaller than the minimum value (= "j + 0.1" mm) of the width Wi of the road 142. The same applies to the minimum value of the width Wo of the communication gas flow path 143 on the fuel chamber outlet side.

Among the plurality of downstream power generation unit groups 102DG, the downstream power generation unit group 102DG located on the lower side discharges the gas (fuel off gas FOG) discharged from the fuel chamber 176 to the outside of the fuel cell stack 100. It can be said that the downstream power generation unit group 102DG is located closer to the discharge hole (the gas passage member 27 provided at the position of the fuel gas discharge manifold 173). Therefore, in the fuel cell stack 100 of the present embodiment, the plurality of downstream power generation unit groups 102DG are compared with one downstream power generation unit group 102DG and the one downstream power generation unit group 102DG from the fuel chamber 176. It is located near the discharge hole for discharging the discharged gas to the outside of the fuel cell stack 100, and the minimum value of the width Wi of the fuel chamber inlet side communication gas flow path 142 and the fuel chamber outlet side communication gas flow path 143. It can be said that it includes another downstream power generation unit group 102DG having a small minimum width Wo.

A-4. Effect of this embodiment:
As described above, the fuel cell stack 100 of the present embodiment includes L (L is an integer of 3 or more, L = 15 in the present embodiment) power generation units 102 arranged side by side in the Z-axis direction. .. Each power generation unit 102 has a single cell 110 including an electrolyte layer 112, an air pole 114 and a fuel pole 116 facing each other in the Z-axis direction with the electrolyte layer 112 interposed therebetween. The fuel cell stack 100 is formed with a plurality of manifolds 161, 162, 171 and 172, 173, each of which is a gas flow path extending over the plurality of power generation units 102. Each power generation unit 102 has a fuel chamber inlet side communication that communicates a fuel chamber 176 facing the fuel electrode 116, a fuel chamber 176, and one of a plurality of manifolds (fuel gas introduction manifold 171 or fuel gas relay manifold 172). A gas flow path 142, and a fuel chamber outlet side communicating gas flow path 143 that communicates the fuel chamber 176 and one of the plurality of manifolds (fuel gas relay manifold 172 or fuel gas discharge manifold 173) are formed. The L power generation units 102 are M (M is an integer of 1 or more, M = 9 in this embodiment) upstream power generation units 102U and N (N is an integer of 2 or more, and the present embodiment). Then, N = 6) downstream power generation units 102D are included. The fuel chamber inlet side communicating gas flow path 142 of each downstream power generation unit 102D communicates with the fuel chamber outlet side communicating gas flow path 143 of each upstream power generation unit 102U via the fuel gas relay manifold 172. Further, in the fuel cell stack 100 of the present embodiment, the height Hd of the portion of the fuel chamber 176 of each downstream power generation unit 102D facing the fuel pole 116 in the Z-axis direction is equal to each other, and each upstream power generation unit The height of the portion of the fuel chamber 176 of 102U facing the fuel electrode 116 in the Z-axis direction is higher than Hu. Further, the N downstream power generation units 102D include a plurality of downstream power generation units 102D in which the width Wi of the fuel chamber inlet side communicating gas flow path 142 and the width W of the fuel chamber outlet side communicating gas flow path 143 are different from each other. Further, the maximum value of the width Wi of the combustion chamber inlet side communicating gas flow path 142 in the N downstream power generation units 102D is the width Wi of the combustion chamber inlet side communicating gas flow path 142 in the M upstream power generation units 102U. The maximum value of the width Wo of the combustion chamber outlet side communication gas flow path 143 in N downstream power generation units 102D, which is smaller than the minimum value, is the fuel chamber outlet side communication gas flow path in M upstream power generation units 102U. It is smaller than the minimum value of the width Wo of 143.

As described above, the fuel cell stack 100 of the present embodiment includes M upstream power generation units 102U and N downstream power generation units 102D, and the fuel chamber inlet side communication gas flow path of each downstream power generation unit 102D. The 142 communicates with the fuel chamber outlet side communication gas flow path 143 of each upstream power generation unit 102U via the fuel gas relay manifold 172. Therefore, the gas (fuel intermediate gas FMG) discharged from the fuel chamber 176 of each upstream power generation unit 102U is introduced into the fuel chamber 176 of each downstream power generation unit 102D, and then the fuel of each downstream power generation unit 102D. It is discharged from the chamber 176 as a fuel off-gas FOG, and finally discharged to the outside of the fuel cell stack 100. Therefore, according to the fuel cell stack 100 of the present embodiment, the gas after being used for the power generation reaction in the upstream power generation unit 102U is also used for the power generation reaction in the downstream power generation unit 102D, and the fuel gas FG It is possible to improve the utilization rate of.

However, since the fuel cell stack 100 of the present embodiment has the above configuration, the gas discharged from the fuel chamber 176 of each power generation unit 102 is discharged to the outside of the fuel cell stack 100 without passing through the other power generation unit 102. There is a possibility that the pressure loss on the fuel electrode side of the fuel cell stack 100 as a whole will increase as compared with the configuration. However, in the fuel cell stack 100 of the present embodiment, the height Hd of the fuel chamber 176 of each downstream power generation unit 102D is higher than the height Hu of the fuel chamber 176 of each upstream power generation unit 102U. Therefore, according to the fuel cell stack 100 of the present embodiment, it is possible to reduce the pressure loss in the fuel chamber 176 of each downstream power generation unit 102D while improving the utilization rate of the fuel gas FG, and as a result, the fuel cell. It is possible to suppress an increase in pressure loss on the fuel electrode side of the stack 100 as a whole.

Further, in the fuel cell stack 100 of the present embodiment, since the height Hd of the fuel cell 176 of each downstream power generation unit 102D is relatively high, the pressure loss in the fuel cell 176 of each downstream power generation unit 102D can be reduced. On the other hand, the flow rate of the gas (fuel intermediate gas FMG) supplied to the fuel chamber 176 tends to vary among the plurality of downstream power generation units 102D, which is caused by the reaction variation in each downstream power generation unit 102D. The power generation performance of the entire fuel cell stack 100 may deteriorate. However, in the fuel cell stack 100 of the present embodiment, the width Wi of the fuel chamber inlet side communicating gas flow path 142 and the width Wo of the fuel chamber outlet side communicating gas flow path 143 are different from each other in the N downstream power generation units 102D. It includes a plurality of downstream power generation units 102D. Therefore, by appropriately setting the width Wi of the fuel chamber inlet side communicating gas flow path 142 and the width Wo of the fuel chamber outlet side communicating gas flow path 143 of each downstream power generation unit 102D, the fuel of each downstream power generation unit 102D is set. It is possible to suppress the variation in the flow rate of the gas supplied to the chamber 176, and as a result, it is possible to suppress the deterioration of the power generation performance of the entire fuel cell stack 100 due to the variation.

Further, in the fuel cell stack 100 of the present embodiment, the N downstream power generation units 102D include a downstream power generation unit group 102DG composed of a plurality of downstream power generation units 102D adjacent to each other in the Z-axis direction. The plurality of downstream power generation units 102D constituting the downstream power generation unit group 102DG compare one downstream power generation unit 102D and the one downstream power generation unit 102D with the gas (fuel) discharged from the fuel chamber 176. The off-gas FOG) is located near the discharge hole (gas passage member 27 provided at the position of the fuel gas discharge manifold 173) for discharging the fuel cell stack 100 to the outside, and the communication gas flow path 142 on the fuel chamber inlet side is located. The width Wi and the other downstream power generation unit 102D having a narrow width W of the fuel chamber outlet side communication gas flow path 143 are included. Of the plurality of downstream power generation units 102D constituting the downstream power generation unit group 102DG, in the downstream power generation unit 102D located relatively close to the discharge hole, the gas supplied to the fuel chamber 176 (fuel intermediate gas FMG). Flow rate tends to increase. In the fuel cell stack 100 of the present embodiment, among the plurality of downstream power generation units 102D constituting the downstream power generation unit group 102DG, in the downstream power generation unit 102D in which the flow rate of the gas supplied to the fuel chamber 176 tends to be large. The width Wi of the fuel chamber inlet side communicating gas flow path 142 and the width W of the fuel chamber outlet side communicating gas flow path 143 are relatively narrow. Therefore, according to the fuel cell stack 100 of the present embodiment, it is possible to suppress variations in the flow rate of the gas supplied to the fuel chambers 176 of the plurality of downstream power generation units 102D constituting the downstream power generation unit group 102DG. As a result, it is possible to effectively suppress the deterioration of the power generation performance of the entire fuel cell stack 100 due to the variation.

Further, in the fuel cell stack 100 of the present embodiment, the N downstream power generation units 102D form a plurality of downstream power generation unit groups 102DG each composed of a plurality of downstream power generation units 102D adjacent to each other in the Z-axis direction. Including. The plurality of downstream power generation unit groups 102DG compare one downstream power generation unit group 102DG with the one downstream power generation unit group 102DG, and compare the gas (fuel off gas FOG) discharged from the fuel chamber 176 with the fuel cell. It is located near the discharge hole (gas passage member 27 provided at the position of the fuel gas discharge manifold 173) for discharging to the outside of the stack 100, and has the minimum value of the width Wi of the communication gas flow path 142 on the fuel chamber inlet side. It includes another downstream power generation unit group 102DG having a small minimum value of the width Wo of the fuel chamber outlet side communicating gas flow path 143. Among the plurality of downstream power generation unit groups 102DG, in the downstream power generation unit group 102DG located relatively close to the discharge hole, the flow rate of the gas (fuel intermediate gas FMG) supplied to the fuel chamber 176 tends to increase. In the fuel cell stack 100 of the present embodiment, among the plurality of downstream power generation unit groups 102DG, in the downstream power generation unit group 102DG in which the flow rate of the gas supplied to the fuel chamber 176 tends to be large, the continuous gas flow on the fuel chamber inlet side The minimum value of the width Wi of the road 142 and the minimum value of the width Wo of the fuel chamber outlet side communication gas flow path 143 are relatively small. Therefore, according to the fuel cell stack 100 of the present embodiment, it is possible to suppress the variation in the flow rate of the gas supplied to the fuel chamber 176 of the downstream power generation unit 102D among the plurality of downstream power generation unit groups 102DG. As a result, it is possible to effectively suppress the deterioration of the power generation performance of the entire fuel cell stack 100 due to the variation.

In the fuel cell stack 100 of the present embodiment, the number N of the downstream power generation unit 102D is smaller than the number M of the upstream power generation unit 102U (N <M). Therefore, according to the fuel cell stack 100 of the present embodiment, it is possible to improve the utilization rate of the fuel gas FG and suppress the shortage of gas (hydrogen) in the downstream power generation unit 102D to reduce the reactivity. it can. However, in the fuel cell stack 100 of the present embodiment, since the number N of the downstream power generation unit 102D is smaller than the number M of the upstream power generation unit 102U, the downstream power generation unit 102D is smaller than the upstream power generation unit 102U. The flow rate of the gas supplied to the fuel chamber 176 per one power generation unit 102 increases, and the flow rate of the gas supplied to the fuel chamber 176 of each downstream power generation unit 102D tends to vary. According to the fuel cell stack 100 of the present embodiment, the width Wi of the fuel chamber inlet side communicating gas flow path 142 and the width W of the fuel chamber outlet side communicating gas flow path 143 are set even in a configuration in which such variation is likely to occur. By making appropriate settings, it is possible to suppress variations in the flow rate of the gas supplied to the fuel chamber 176 of each downstream power generation unit 102D, and as a result, the power generation performance of the entire fuel cell stack 100 due to the variations. Can be suppressed from decreasing.

B. Modification example:
The technique disclosed in the present specification is not limited to the above-described embodiment, and can be transformed into various forms without departing from the gist thereof. For example, the following modifications are also possible.

The configuration of the fuel cell stack 100 in the above embodiment is merely an example and can be variously modified. For example, in the fuel cell stack 100 of the above embodiment, the number L of power generation units 102, the number M of upstream power generation units 102U, the number N of downstream power generation units 102D, the number of downstream power generation unit groups 102DG, and each downstream power generation. The number of downstream power generation units 102D constituting the unit group 102DG is merely an example and can be arbitrarily changed. For example, in the above embodiment, the number N of the downstream power generation unit 102D is smaller than the number M of the upstream power generation unit 102U (N <M), but the number N of the downstream power generation unit 102D is the number M of the upstream power generation unit 102U. It may be the above (N ≧ M).

Further, in the above embodiment, the fuel chamber inlet side communication gas flow path 142 of each downstream power generation unit 102D communicates with the fuel chamber outlet side of each upstream power generation unit 102U via one manifold (fuel gas relay manifold 172). Although it communicates with the gas flow path 143, the fuel chamber inlet side communication gas flow path 142 of each downstream power generation unit 102D communicates with the fuel chamber outlet side communication gas flow path 142 of each upstream power generation unit 102U via a plurality of manifolds. It may communicate with 143. For example, the fuel chamber inlet side communicating gas flow path 142 of each downstream power generation unit 102D communicates with the gas flow path in the plane direction formed other than the upstream power generation unit 102U via one manifold, and the gas flow path May communicate with the fuel chamber outlet side communication gas flow path 143 of each upstream power generation unit 102U via the fuel gas relay manifold 172.

Further, in the above embodiment, the width Wi of the fuel chamber inlet side communicating gas flow path 142 and the width W of the fuel chamber outlet side communicating gas flow path 143 of each power generation unit 102 are merely examples and can be variously modified. For example, in the above embodiment, the six downstream power generation units 102D include a plurality of downstream power generation units 102D having different width Wis of the fuel chamber inlet side communication gas flow paths 142, and the six downstream power generation units 102D. The unit 102D is said to include a plurality of downstream power generation units 102D having different widths Wo of the fuel chamber outlet side communicating gas flow path 143, but the width Wi of the fuel chamber inlet side communicating gas flow path 142 and the fuel chamber outlet side communication. One of the widths Wo of the gas flow path 143 may have the same width of the communicating gas flow paths in each of the six downstream power generation units 102D. In this case, of the fuel chamber inlet side communicating gas flow path 142 and the fuel chamber outlet side communicating gas flow path 143, the communicating gas flow path having the same width is the specific communicating gas flow path within the scope of the claims. Equivalent to. Further, for example, in the above embodiment, the width Wi of the fuel chamber inlet side communicating gas flow path 142 and the width Wo of the fuel chamber outlet side communicating gas flow path 143 in each of the nine upstream power generation units 102U are configured to be equal. However, the widths of the communicating gas flow paths may not be equal for at least one of the width Wi of the communication gas flow path 142 on the fuel chamber inlet side and the width Wo of the communication gas flow path 143 on the fuel chamber outlet side.

Further, in the above embodiment, the width Wi of the fuel chamber inlet side communicating gas flow path 142 and the fuel chamber outlet side communicating gas flow path of the plurality of (three) downstream power generation unit 102Ds constituting each downstream power generation unit group 102DG. Although the width Wo of 143 is different from each other, at least one of the width Wi and the width Wo may be the same for at least a part of the downstream power generation units 102D among the plurality of downstream power generation units 102D. That is, each downstream power generation unit group 102DG may include a plurality of downstream power generation units 102D in which at least one of the width Wi and the width Wo is the same as each other. For example, of the three downstream power generation units 102D constituting the lower downstream power generation unit group 102DG1 shown in FIG. 11, the width Wi of the combustion chamber inlet side communicating gas flow path 142 in the downstream power generation unit 102D located at the uppermost side. And the width Wi of the communication gas flow path 142 on the fuel chamber inlet side in the downstream power generation unit 102D located at the center may both be "j + 0.2" mm. Alternatively, the width Wo of the combustion chamber outlet side communication gas flow path 143 in the downstream power generation unit 102D located at the lowermost side among the three downstream power generation units 102D constituting the lower downstream power generation unit group 102DG1 and the center. The width Wo of the combustion chamber outlet side communication gas flow path 143 in the downstream power generation unit 102D located at may be km. Also in these modifications, the plurality of downstream power generation units 102D constituting the downstream power generation unit group 102DG are compared with one downstream power generation unit 102D and the one downstream power generation unit 102D as fuel. The fuel off-gas FOG discharged from the chamber 176 is located near the discharge hole for discharging the fuel off-gas FOG to the outside of the fuel cell stack 100, and the fuel chamber inlet side communicating gas flow path 142 and / or the fuel chamber outlet side communicating gas flow path 143. It can be said that the width Wi and Wo include another downstream power generation unit 102D having a narrow width.

Further, the configuration of each manifold and each communicating gas flow path in the above embodiment is merely an example and can be variously deformed. For example, in the above embodiment, the number of the fuel chamber inlet side communicating gas flow path 142 and the fuel chamber outlet side communicating gas flow path 143 formed in each downstream side power generation unit 102D is one, but each downstream side power generation unit. The number of the fuel chamber inlet side communicating gas flow path 142 and the fuel chamber outlet side communicating gas flow path 143 formed in the 102D can be arbitrarily set and may be plural. Further, in the above embodiment, the space between the outer peripheral surface of the shaft portion of each bolt 22 and the inner peripheral surface of each communication hole 108 is used as each manifold, but instead of this, the shaft of each bolt 22 is used. Axial holes may be formed in the portion, and the holes may be used as each manifold. Further, each manifold may be provided separately from each communication hole 108 into which each bolt 22 is inserted.

Further, in the above embodiment, the SOFC that generates power by utilizing the electrochemical reaction between hydrogen contained in the fuel gas and oxygen contained in the oxidizing agent gas is targeted, but the present invention comprises an electrolysis reaction of water. It is also applicable to an electrolytic cell stack having a plurality of electrolytic cell units, which are constituent units of a solid oxide fuel cell (SOEC) that uses it to generate hydrogen. The configuration of the electrolytic cell stack is not described in detail here because it is known as described in, for example, Japanese Patent Application Laid-Open No. 2016-81813, but is generally the same as the fuel cell stack 100 in the above-described embodiment. It is a configuration. That is, the fuel cell stack 100 in the above-described embodiment may be read as an electrolytic cell stack, the power generation unit 102 may be read as an electrolytic cell unit, and the single cell 110 may be read as an electrolytic single cell. However, during the operation of the electrolytic cell stack, a voltage is applied between both electrodes so that the air electrode 114 is positive (anode) and the fuel electrode 116 is negative (cathode), and the raw material gas is passed through the manifold. Water vapor is supplied as. As a result, an electrolysis reaction of water occurs in each electrolytic cell unit, hydrogen gas is generated in the fuel chamber 176, and hydrogen is taken out to the outside of the electrolytic cell stack via the manifold. Even in the electrolytic cell stack having such a configuration, if the same configuration as that of the above embodiment is adopted, the pressure loss of the electrolytic cell stack as a whole is improved while improving the utilization rate of the gas supplied to the fuel chamber of each electrolytic cell unit. Further, it is possible to suppress the deterioration of the performance of the entire electrolytic cell stack due to the variation in the flow rate of the gas supplied to the fuel chamber of each electrolytic cell unit.

Further, in the above embodiment, the solid oxide fuel cell (SOFC) has been described as an example, but the present invention has a solid polymer fuel cell (PEFC), a phosphoric acid fuel cell (PAFC), and a molten carbonate fuel cell. It is also applicable to other types of fuel cell stacks (or electrolytic cell stacks) such as fuel cells (MCFCs).

22: Bolt 24: Nut 26: Insulation sheet 27: Gas passage member 28: Main body 29: Branch 100: Fuel cell stack 102: Fuel cell power generation unit 102D: Downstream power generation unit 102DG: Downstream power generation unit group 102U: Upstream Side power generation unit 104: End plate 106: End plate 108: Communication hole 110: Single cell 112: Electrolyte layer 114: Air pole 116: Fuel pole 120: Separator 121: Hole 124: Joint 130: Air pole side frame 131: Hole 132: Air chamber inlet side communication gas flow path 133: Air chamber outlet side communication gas flow path 134: Air electrode side current collector 140: Fuel pole side frame 141: Hole 142: Fuel chamber inlet side communication gas flow path 143: Fuel Room outlet side communication gas flow path 144: Fuel electrode side current collector 145: Electrode facing part 146: Interconnector facing part 147: Connecting part 149: Spacer 150: Interconnector 161: Oxidizing agent gas introduction manifold 162: Oxidating agent gas discharge Manifold 166: Air chamber 171: Fuel gas introduction manifold 172: Fuel gas relay manifold 173: Fuel gas discharge manifold 176: Fuel chamber FG: Fuel gas FMG: Fuel intermediate gas FOG: Fuel off gas Hd: Height Hu: Height OG: Oxidizing agent gas OOG: Oxidizing agent off gas Wi: Width Wo: Width j: Inlet side reference width k: Outlet side reference width

Claims (5)

L (L is 3) having an electrochemical reaction single cell containing an electrolyte layer and an air electrode and a fuel electrode facing each other in the first direction with the electrolyte layer interposed therebetween, and arranged side by side in the first direction. In an electrochemical reaction cell stack having (the above integers) the electrochemical reaction units,
The electrochemical reaction cell stack is formed with a plurality of manifolds, each of which is a gas flow path extending over the plurality of the electrochemical reaction units.
For each electrochemical reaction unit,
The fuel chamber facing the fuel electrode and
An inlet-side communicating gas flow path that communicates the fuel chamber with one of the plurality of manifolds,
An outlet-side communicating gas flow path that communicates the fuel chamber with one of the plurality of manifolds,
Is formed,
The L electrochemical reaction units are
With M (M is an integer of 1 or more) first electrochemical reaction unit,
N (N is an integer of 2 or more) second electrochemical reaction units, and the inlet-side communicating gas flow path of each of the second electrochemical reaction units is via at least one of the manifolds. N second electrochemical reaction units communicating with the outlet-side communicating gas flow path of each first electrochemical reaction unit.
Including
The heights of the portions of the fuel chamber of each of the second electrochemical reaction units facing the fuel electrode in the first direction are equal to each other, and the fuel chambers of the first electrochemical reaction units are located. Higher than the height of the portion facing the fuel electrode in the first direction in
The N second electrochemical reaction units are a plurality of the second electrochemical reaction units having different widths of at least one of the inlet side communicating gas flow path and the outlet side communicating gas flow path. Including electrochemical reaction units
The maximum value of the width of the specific communicating gas flow path in the N second electrochemical reaction units is smaller than the minimum value of the width of the specific communicating gas flow path in the M first electrochemical reaction units. ,
It is characterized by an electrochemical reaction cell stack. In the electrochemical reaction cell stack according to claim 1,
The N second electrochemical reaction units include an electrochemical reaction unit group composed of a plurality of the second electrochemical reaction units adjacent to each other in the first direction.
The plurality of the second electrochemical reaction units constituting the electrochemical reaction unit group are
With the second electrochemical reaction unit of one
Compared with the first and second electrochemical reaction units, the gas discharged from the fuel chamber is located near the discharge hole for discharging the gas discharged to the outside of the electrochemical reaction cell stack, and the specific communicating gas flow. With the other second electrochemical reaction unit with a narrow path,
including,
It is characterized by an electrochemical reaction cell stack. In the electrochemical reaction cell stack according to claim 1 or 2.
The N second electrochemical reaction units include a plurality of electrochemical reaction unit groups composed of a plurality of the second electrochemical reaction units adjacent to each other in the first direction.
The plurality of electrochemical reaction unit groups
With the above-mentioned electrochemical reaction unit group of one
Compared to the one electrochemical reaction unit group, it is located near the discharge hole for discharging the gas discharged from the fuel chamber to the outside of the electrochemical reaction cell stack, and is located in the specific communicating gas flow path. With the other electrochemical reaction unit group having a smaller minimum width,
including,
It is characterized by an electrochemical reaction cell stack. In the electrochemical reaction cell stack according to any one of claims 1 to 3.
The number N of the second electrochemical reaction units is smaller than the number M of the first electrochemical reaction units.
It is characterized by an electrochemical reaction cell stack. In the electrochemical reaction cell stack according to any one of claims 1 to 4.
The electrochemical reaction cell stack is a fuel cell single cell.

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