JP2012113931A - Auxiliary device for fuel cell and fuel cell - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an auxiliary device for a fuel cell and a fuel cell which are improved temperature uniformity.SOLUTION: An auxiliary device for a fuel cell includes: a first inflow section into which a first gas, which is one of a residual fuel gas and a residual oxidant gas after power generation by a fuel cell, flows; a second inflow section into which a second gas, which is the other of the residual fuel gas and the residual oxidant gas, flows; a dividing section for dividing the first gas, flowing from the first inflow section, into two or more; a first mixing section for mixing and burning a part of the first gas divided at the dividing section and the second gas flowing from the second inflow section; and a second mixing section for mixing and burning an exhaust gas after burned at the first mixing section and the other part of the divided first gas.

Description

  The present invention relates to a fuel cell auxiliary device and a fuel cell.

  A solid oxide fuel cell (hereinafter also referred to as SOFC) using a solid oxide as an electrolyte is known. The SOFC has, for example, a stack (fuel cell stack) in which a large number of fuel cells each having a fuel electrode and an air electrode are stacked on each surface of a plate-shaped solid electrolyte body. Electric power is generated by supplying a fuel gas and an oxidant gas (for example, oxygen in the air) to the fuel electrode and the air electrode, respectively, and causing a chemical reaction through the solid electrolyte body.

  Since the SOFC operates at a high temperature of 600 to 1000 ° C., a structure for maintaining this operating temperature is required. For this reason, a solid oxide fuel cell module in which a fuel cell stack and a combustor are integrated is used.

The combustor mixes and burns the remaining fuel gas and oxidant gas after power generation, and it is desirable that the combustion in the inside be uniform.
Here, regarding a combustor for a polymer electrolyte fuel cell (PEFC), a technique for monitoring a combustion temperature with a thermocouple and controlling a combustion air pump is disclosed (see Patent Document 1).
However, this technology requires a combustion air pump and is not suitable for a SOFC aimed at a low price. In SOFC, it is necessary to perform combustion control and prevention of overheating by different means.

JP-A-9-92311

  It is an object of the present invention to provide a fuel cell auxiliary device and a fuel cell with improved temperature uniformity and thermal efficiency.

  A fuel cell auxiliary device according to the present invention includes a first inflow portion into which a first gas that is one of a residual fuel gas after power generation in the fuel cell and a residual oxidant gas after power generation flows, A second inflow section into which a second gas, which is the other of the remaining fuel gas and the remaining oxidant gas, and a first gas flowing in from the first inflow section are divided into two or more. A first mixing section for mixing and burning a part of the first gas divided by the dividing section and the second gas flowing in from the second inflow section, and the first mixing section And a second mixing section for mixing and burning the exhaust gas after combustion and the other part of the first gas.

  One of the remaining fuel gas and the remaining oxidant gas is divided into two or more and mixed in the first and second mixing sections, so that the heat generated when the fuel gas and the oxidant gas are mixed is changed to the first and second. The temperature uniformity can be improved.

(1) Here, the amount of the first gas flowing into the first mixing portion from the partitioning portion is made smaller than the amount of the first gas flowing into the second mixing portion from the partitioning portion. May be.
The heat generation in the first and second mixing sections can be increased stepwise. That is, the state of combustion (the amount of heat generated by heat generation) can be controlled.

(2) In (1), there are first and second paths arranged corresponding to each of the second and first mixing sections and through which fuel gas before power generation flows in order, and the fuel gas is modified. A reformer may be further provided.

  The reforming reaction (endothermic reaction) in the reformer is more popular upstream with a large amount of unreformed fuel gas. For this reason, by arranging the first and second mixing sections where the amount of generated heat increases stepwise corresponding to the downstream and upstream of the path in the reformer, heat generation and heat absorption are balanced, and temperature uniformity is achieved. In addition, thermal efficiency can be improved.

(3) The division part further divides the first gas flowing in from the first inflow part into three or more, and is further divided in the second mixing part by the exhaust gas after combustion and the division part. A third mixing section that mixes and burns another part of the first gas, and the third mixing section includes the exhaust gas after combustion in the second mixing section and the dividing section. Another part of the first gas that has been separated may be mixed and burned.

  One of the remaining fuel gas and the remaining oxidant gas is divided into three or more and mixed in the first to third mixing sections, so that the heat generated when the fuel gas and the oxidant gas are mixed is changed to the first to third. Can be dispersed in the mixing part. Therefore, the temperature uniformity can be further improved.

(4) In (3), the fuel gas is reformed by having first to third paths arranged corresponding to each of the third to first mixing sections and through which fuel gas before power generation flows in order. A reformer may be further provided.

  The reforming reaction (endothermic reaction) in the reformer is more popular upstream with a large amount of unreformed fuel gas. For this reason, by arranging the first to third mixing sections where the heat generation amount increases stepwise corresponding to the downstream, middle flow, and upstream of the path in the reformer, the heat generation and heat absorption are balanced, Uniformity and thermal efficiency can be further improved.

(5) The first gas may be the remaining oxidant gas, and the second gas may be the remaining fuel gas. Since the flow rate of the oxidant gas is larger than that of the fuel gas and easy to control, it is particularly preferable that the first gas is the remaining oxidant gas.

(6) The first gas may be the remaining fuel, and the second gas may be the remaining oxidant gas.

(7) The apparatus further includes a second dividing unit that divides the second gas flowing in from the second inflow unit into two or more, and the first mixing unit is a part of the portion divided by the dividing unit. The first gas and a part of the second gas divided by the second division part are mixed and burned, and the second mixing part is an exhaust gas after combustion in the first mixing part, The other part of the first gas divided by the dividing part and the other part of the second gas divided by the second dividing part may be mixed and burned.

  By dividing and mixing both the remaining fuel gas and the remaining oxidant gas into two or more, the heat generated when the fuel gas and the oxidant gas are mixed can be further dispersed.

  The fuel cell may include the fuel cell auxiliary device described above. It is possible to ensure temperature uniformity in the fuel cell. In addition, the thermal efficiency of the fuel cell can be improved.

  ADVANTAGE OF THE INVENTION According to this invention, the auxiliary | assistant for fuel cells and fuel cell which improved the uniformity of temperature and thermal efficiency can be provided.

1 is a perspective view showing a fuel cell system 10 according to a first embodiment of the present invention. 2 is an exploded perspective view showing a fuel cell stack 100 and an auxiliary device 200. FIG. 2 is a partial cross-sectional view showing a fuel cell stack 100 and an auxiliary device 200. FIG. 2 is an exploded perspective view showing a fuel cell stack 100. FIG. It is a top view showing the auxiliary device 200. 3 is a top view illustrating a first layer 210 of the auxiliary device 200. FIG. 3 is a perspective view illustrating a first layer 210 of the auxiliary device 200. FIG. 3 is a perspective view illustrating a second layer 220 of the auxiliary device 200. FIG. 3 is a perspective view illustrating a third layer 230 of the auxiliary device 200. FIG. It is a perspective view showing the 3rd layer 230a concerning a modification. It is a perspective view showing the 1st layer 210x of auxiliary equipment 200x concerning a comparative example of the present invention. It is a perspective view showing the 1st layer 210a of auxiliary equipment 200a concerning a 2nd embodiment of the present invention. It is a perspective view showing the 1st layer 210b of auxiliary equipment 200b concerning a 2nd embodiment of the present invention. It is a perspective view showing the 1st layer 210c of auxiliary equipment 200c concerning a 4th embodiment of the present invention.

(First embodiment)
Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings.
FIG. 1 is a perspective view showing a fuel cell system 10 according to the first embodiment of the present invention. 2 and 3 are an exploded perspective view and a partial sectional view showing the fuel cell stack 100 and the auxiliary device 200, respectively. FIG. 3 shows a state in which the fuel cell stack 100 is cut along a line connecting through holes 112 and 114 described later.

  As shown in FIG. 1, the fuel cell system 10 includes a solid oxide fuel cell 20 and a control unit 30. The solid oxide fuel cell 20 is a device that generates power upon receipt of fuel gas and oxidant gas, and includes a fuel cell stack 100, an auxiliary device 200, and a heating element 300.

  The fuel gas includes hydrogen, hydrocarbon as a reducing agent, mixed gas of hydrogen and hydrocarbon, fuel gas obtained by passing these gases through water at a predetermined temperature, and fuel obtained by mixing these gases with water vapor. Gas etc. are mentioned. The hydrocarbon is not particularly limited, and examples thereof include natural gas, naphtha, and coal gasification gas. The fuel gas is preferably hydrogen. These fuel gases may be used alone or in combination of two or more. Moreover, you may contain inert gas, such as nitrogen and argon of 50 volume% or less.

  Examples of the oxidant gas include a mixed gas of oxygen and another gas. Further, the mixed gas may contain 80% by volume or less of an inert gas such as nitrogen and argon. Of these oxidant gases, air (containing about 80% by volume of nitrogen) is preferred because it is safe and inexpensive.

  The control unit 30 controls the power generation state in the solid oxide fuel cell 20, in particular, the fuel cell stack 100. For example, the temperature of the fuel cell stack 100 is monitored by a temperature sensor (thermocouple or the like), and the supply amount of the fuel gas (or oxidant gas) to the fuel cell stack 100 is corrected to a target value.

  The fuel cell stack 100 has a substantially rectangular parallelepiped shape, and has an upper surface 101, a bottom surface 102, and through holes 111 to 118, and the member 120 is connected thereto. The through holes 111 to 114 pass through the vicinity of the upper surface 101 and the side of the bottom surface 102 (near the side of the frame portion 160 described later), and the through holes 115 to 118 close to the apex of the upper surface 101 and the bottom surface 102 (the frame portion 160 described later). Through the apex of Connecting members (bolts 41 to 48, which are fasteners, and nuts 51 to 58) are attached to the through holes 111 to 118, respectively. The nuts 53 and 57 are not shown in any of FIGS. 1 to 3 for easy understanding.

  A member 120 and a member 250, which will be described later, are disposed in the opening of the through hole 111 on each of the top surface 101 side and the bottom surface 102 side. The bolt 41 is inserted into the through hole of the member 120 (member 121), the through hole 111, and the through hole 254 of the member 250, and the nut 51 is screwed. As a result, the member 120, the fuel cell stack 100, and the auxiliary device 200 (member 250) are connected by the bolt 41 and the nut 51.

  The member 120 includes a member 121 and an introduction pipe 122. The member 121 has a substantially cylindrical shape, and has a substantially flat top and bottom surfaces, a curved side surface, and a through-hole penetrating between the top and bottom surfaces. The through hole of the member 121 and the inside of the introduction pipe 122 communicate with each other.

  The diameter of the through-hole of the member 121 and the through-hole 111 are substantially the same. Since the diameter of the shaft of the bolt 41 is smaller than these diameters, the oxidant gas (air) passes between the through hole of the member 121 and the shaft of the bolt 41 and between the through hole 111 and the shaft of the bolt 41. That is, the oxidant gas (air) flows from the introduction pipe 122 and flows into the fuel cell stack 100 through the through hole of the member 121 and the through hole 111.

  The through hole 111 communicates with the through hole 254 of the member 250, but the lower surface 252 of the member 250 is sealed by the nut 51. As a result, inflow and outflow of the oxidant gas (air) from the opening of the through hole 111 on the bottom surface 102 side are prevented.

  The bolt 42 is inserted into the through hole 112 and a through hole 264 of the member 260 described later, and the nut 52 is screwed. As a result, the fuel cell stack 100 and the auxiliary device 200 (member 260) are connected by the bolt 42 and the nut 52. Here, since the diameter of the shaft of the bolt 42 is smaller than the diameter of the through hole 112, the remaining fuel gas after power generation passes between the shafts of the through hole 112 and the bolt 42. That is, the through hole 112 functions as a flow path for supplying the remaining fuel gas after power generation from the fuel cell stack 100 to the auxiliary device 200.

  The bolt 43 is inserted into the through hole 113 and a through hole 274 of the member 270 described later, and the nut 53 is screwed. As a result, the fuel cell stack 100 and the auxiliary device 200 (member 270) are connected by the bolt 43 and the nut 53. Here, since the diameter of the shaft of the bolt 43 is smaller than the diameter of the through hole 113, the remaining oxidant gas after power generation passes between the through hole 113 and the bolt 43. That is, the through hole 113 functions as a flow path for supplying the remaining oxidant gas after power generation from the fuel cell stack 100 to the auxiliary device 200.

  Bolts 44 are inserted into the through holes 114 and through holes 64 of the member 60 described later, and the nuts 54 are screwed. Here, since the diameter of the shaft of the bolt 44 is smaller than the diameter of the through hole 114, the reformed fuel gas passes between the through hole 114 and the bolt 44. That is, the through hole 114 functions as a flow path for supplying the reformed fuel gas from the auxiliary device 200 to the fuel cell stack 100.

  The fuel cell stack 100 is configured by laminating a plurality of flat plate fuel cells 150 that are power generation units. A plurality of fuel cells 150 are electrically connected in series.

As shown in FIG. 4, the fuel cell 150 is a so-called fuel electrode support membrane type fuel cell, and a cell body 153 is disposed between a pair of upper and lower metal interconnectors 151 and 152. . An air flow path 154 and a fuel gas flow path 155 are disposed between the cell main body 153 and the interconnectors 151 and 152.
The cell body 153 is configured by laminating an air electrode (cathode) 157 and a fuel electrode (anode) 158 above and below the solid electrolyte body 156. A current collector 159 is disposed between the air electrode 157 and the interconnector 151 in order to ensure electrical connection.

Examples of the material of the solid electrolyte body 156 include ZrO 2 ceramic, LaGaO ₃ ceramic, BaCeO ₃ ceramic, SrCeO ₃ ceramic, SrZrO ₃ ceramic, and CaZrO ₃ ceramic.

As a material of the air electrode 157, for example, various metals, metal oxides, metal double oxides, and the like can be used. Examples of the metal include metals such as Pt, Au, Ag, Pd, Ir, Ru, and Rh, or alloys containing two or more metals. Furthermore, examples of the metal oxide include oxides such as La, Sr, Ce, Co, Mn, and Fe (La ₂ O ₃ , SrO, Ce ₂ O ₃ , Co ₂ O ₃ , MnO _2, FeO, and the like). It is done. As the double oxide, a double oxide containing at least La, Pr, Sm, Sr, Ba, Co, Fe, Mn, etc. (La _1-x Sr _x CoO ₃ -based double oxide, La _1-x Sr _x FeO ₃ -based double oxide, La _1-x Sr _x Co _1-y Fe _y O ₃ -based double oxide, La _{1 -x} Sr _x MnO ₃ -based double oxide, Pr _1-x Ba _x CoO ₃ -based double oxide And Sm _1-x Sr _x CoO ₃ -based double oxide).

Examples of the material of the fuel electrode 158 include ZrO ₂ ceramics such as zirconia stabilized by at least one of metals such as Ni and Fe and rare earth elements such as Sc and Y, CeO ₂ ceramics, and the like. The mixture with at least 1 sort (s) of ceramics etc. are mentioned. Moreover, metals, such as Pt, Au, Ag, Pd, Ir, Ru, Rh, Ni, and Fe, are mentioned. These metals may be used alone or in an alloy of two or more metals. Further, a mixture (including cermet) of these metals and / or alloys and at least one of each of the above ceramics may be mentioned. Moreover, the mixture of the oxide of metals, such as Ni and Fe, and at least 1 type of each of the said ceramic etc. are mentioned.

  The fuel cell 150 has a frame portion 160 at the outer peripheral edge thereof. The frame portion 160 includes interconnectors 151 and 152 (outer peripheral edge portions), an air electrode frame 161, an insulating frame 162, a separator 163 (outer peripheral edge portion), and a fuel electrode frame 164. The air electrode frame 161, the insulating frame 162, the separator 163, and the fuel electrode frame 164 are all rectangular, and are made of metal except for the ceramic insulating frame 162. The air electrode frame 161 and the fuel electrode frame 164 may be made of ceramics. The separator 163 is joined to the cell body 153 and blocks gas movement between the air flow path 154 and the fuel gas flow path 155.

  Through holes corresponding to the aforementioned through holes 111 to 118 are formed in the frame portion 160. In FIG. 3, cross sections of the through holes 112 and 114 are illustrated. The reformed fuel gas flows from the auxiliary device 200 into the fuel gas passage 155 through the through hole 114. The fuel gas after power generation flows out from the fuel gas flow path 155 to the auxiliary device 200 through the through hole 112.

Hereinafter, an outline of the auxiliary device 200 will be described.
As shown in FIG. 3, the auxiliary device 200 includes a mixer 21, a reformer 22, and a combustor 23 (combustion chambers 23 a and 23 b), and is divided into a first layer 210 to a third layer 230. The mixer 21 and the reformer 22 are disposed in the first layer 210 and the second layer 220, respectively. In the combustor 23, the combustion chamber 23 a is disposed in the first layer 210 to the third layer 230, and the combustion chamber 23 b is disposed in the third layer 230.

  The mixer 21 is disposed on the partition plate 207 and mixes the remaining fuel gas after power generation using the reformed fuel gas and the remaining oxidant gas after power generation to generate a mixed gas. However, the mixer 21 may be disposed along the partition plate 207 without directly contacting the partition plate 207.

  If the gas mixed in the mixer 21 is at a temperature equal to or higher than the ignition point, it is burned in the mixer 21 (in the first layer 210) (so-called flame combustion).

  The combustion chambers 23a and 23b are disposed on the partition plate 221 and the partition plate 208 (in contact with the partition plates 221 and 208), respectively. However, the combustion chambers 23a and 23b may be disposed along the partition plates 221 and 208 without directly contacting the partition plates 221 and 208, respectively.

  The remaining fuel gas (anode exhaust gas) G02 and the remaining oxidant (cathode exhaust gas) G12 generated from the fuel cell stack 100 flow into the mixer 21 and are mixed. The remaining fuel gas G02 flows into the mixer 21 via a through hole 112 of the fuel cell stack 100, a through hole 264, a communication hole 265, and an inflow hole 266 of a member 260 described later. The remaining oxidant gas G12 flows into the mixer 21 via a through hole 113 of the fuel cell stack 100, a through hole 274, a communication hole 275, and an inflow hole 276 of a member 270 described later.

  The remaining fuel gas and the remaining oxidant (mixed gas G2) mixed in the mixer 21 are combusted by the combustion catalyst in the combustor 23 (combustion chambers 23a and 23b). The burned mixed gas is discharged from the pipe 293 as the exhaust gas G3. Note that the combustion catalyst may be disposed only in the combustion chamber 23b without being disposed in the combustion chamber 23a.

  The reformer 22 is filled with a reforming catalyst to reform the fuel gas. The fuel gas G00 flows into the reformer 22 from the pipe 291, and the reformed fuel gas G01 passes through the pipe 292, the pipe 66 of the member 60, the through hole 64, and the through hole 114 of the fuel cell stack 100. It flows into the battery stack 100 and is used for power generation.

  Hereinafter, the auxiliary device 200 will be described in detail with reference to FIGS. 2 and 5 to 9. FIG. 5 is a top view of the auxiliary device 200. FIG. 6 is a top view illustrating the first layer 210 of the auxiliary device 200. It is the figure which excluded the upper board 201 of the auxiliary device 200, and was expanded. 7 to 9 are perspective views showing the inside of the first layer 210 to the third layer 230 of the auxiliary device 200, excluding the upper plate 201 and the partition plates 207 and 208 of the auxiliary device 200, respectively.

  The auxiliary device 200 includes an upper plate 201, a bottom plate 202, side plates 203 to 206, and partition plates 207 and 208. The top plate 201, the bottom plate 202, and the side plates 203 to 206 form a substantially rectangular parallelepiped space with the inside and the outside of the auxiliary device 200 separated from each other. This space is partitioned into first layer 210 to third layer 230 in order from the top by partition plates 207 and 208.

  Members (manifolds) 250 to 270 are connected to the side plates 203 to 205 of the auxiliary device 200, respectively. The members 250 to 270 have planar upper surfaces 251 to 271, planar lower surfaces 252 to 272, and curved side surfaces 253 to 273, respectively. Through holes 254 to 274 are formed between the upper surfaces 251 to 271 and the lower surfaces 252 to 272. Further, the members 260 and 270 have communication holes 265 and 275 and inflow holes 266 and 276 that allow the through holes 264 to 274 to communicate with the inside of the first layer 210.

  The member 60 is disposed along the side plate 206 of the auxiliary device 200 on the bottom surface 102 side of the through hole 114. The member 60 has a substantially cylindrical shape, and has a planar upper surface 61, a planar lower surface 62, and a curved side surface 63. A through hole 64 is formed between the upper surface 61 and the lower surface 62, and a pipe 66 communicating with the through hole 64 is connected to the side surface 63.

Pipes 291 to 293 are connected to the auxiliary device 200.
A member 70 is connected between the pipe 292 and the member 60, and the reformed fuel gas can be supplied from the auxiliary device 200 to the fuel cell stack 100. The member 70 has members 71 and 72.
The member 71 has hollows communicating with each other, and has joints 73 and 74 arranged at right angles to each other.
The member 72 has a hollow communicating with each other, and has a pipe 75 and a joint 76 arranged at right angles to each other.

  The joints 73, 74, and 76 are tightened and connected to the pipes 292, 75, and 66. Here, the members 71, 72, and 60 can be rotated and moved until the tightening is completed.

As shown in FIGS. 5 to 7, the mixer 21 is partitioned by partition plates 211 to 215 and 218.
The partition plate 211 is configured by connecting partition plates 2111 to 2114.
The partition plate 212 is configured by connecting partition plates 2121 to 2123.
The partition plate 213 is configured by connecting partition plates 2131 to 2133.
The partition plate 214 is configured by connecting partition plates 2141 to 2143.
The partition plate 218 has an opening 219 in which a net is disposed.

  The remaining fuel gas flows into the mixer 21 from the member 260 through the inflow hole 266. That is, the member 260 functions as an inflow portion into which the first and second gases, which are one or the other of the remaining fuel gas after power generation in the fuel cell and the remaining oxidant gas after power generation, flow.

  On the other hand, the remaining oxidant gas flows into the mixer 21 from the member 270 through the inflow hole 276. That is, the member 260 functions as an inflow portion into which the first and second gases, which are one or the other of the remaining fuel gas after power generation in the fuel cell and the remaining oxidant gas after power generation, flow.

  The remaining oxidant gas that flows in is divided into three by the partition plates 212 and 213. In other words, the partition plates 212 and 213 function as a section that separates the first gas flowing from the inflow section into two or more.

  In this way, the remaining fuel gas is not divided, and the remaining oxidant gas is divided into three divided gases F1 to F3 (see FIG. 7). By classifying the remaining oxidant gas and mixing it with the remaining fuel gas, the combustion in the mixer 21 is made uniform.

The remaining fuel gas from the inflow hole 266 flows into the space formed by the partition plate 211 and the side plates 204 and 205.
On the other hand, the remaining oxidant gas from the inflow hole 276 is divided into three gas segments F1 to F3, (1) in the space formed by the partition plate 212 and the side plate 205, and (2) the partition plates 212 and 213. And (3) the space formed by the partition plates 213 and 214, respectively.

  As a result, the remaining fuel gas and the remaining oxidant gas are merged (mixed) at the merge points P1 to P3 as follows. That is, the merging points P1 to P3 function as a mixing unit that mixes and burns a part of the first gas divided by the dividing unit and the second gas flowing in from the second inflowing unit.

The remaining fuel gas travels in the Y direction and the X direction along the partition plate 211, and is mixed with the segment gas F1 at the junction P1.
The gas mixed at the merging point P1 proceeds along the partition plate 212 in the −Y direction and the −X direction, and then proceeds along the partition plates 211 and 214 in the −Y direction and the X direction. The merging point P2 , Mixed with the division gas F2.
The gas mixed at the junction P2 proceeds in the −Y direction and the −X direction along the partition plate 213, and then proceeds in the −Y direction and the X direction along the side plates 204 and 203, at the junction P3. , Mixed with the division gas F3.
The gas mixed at the junction P3 proceeds in the X direction and the Y direction along the side plates 203 and 206, and then flows into the combustion chamber 23a from the opening 219.

In this way, the remaining oxidant gas from the inflow hole 276 is divided into the division gases F1 to F3, and merges with the remaining fuel gas from the inflow hole 266 at the merge points P1 to P3. A mixed gas in which the oxidant gas is mixed is generated.
Since gas is mixed by being dispersed at the junction points P1 to P3, uniformity of combustion in the mixer 21 is achieved at the time of combustion.

Here, by making the ratio of the flow rates of the division gases F1 to F3 to an appropriate value, it is possible to promote the uniform heat generation amount in the mixer 21. For example, in FIG. 6, the sectional area ratio of each segment gas (F1 to F3) flow path obtained from the widths d1 to d3 is adjusted to a range of 1: 1: 1 to 1: 2: 3, and the segment gas F1 to It is conceivable to increase the flow rate of F3 step by step.
At this time, as will be described later, the uniformity of temperature at the junctions P1 to P3 can be improved by making the junctions P1 to P3 correspond to the flow paths (path points Q3 to Q1) of the reformer 22. .

  As shown in FIG. 8, the second layer 220 is partitioned by partition plates 221 to 224. The partition plate 221 has openings 226 and 227 communicating with the pipes 291 and 292. Nets 228 and 229 are arranged to face the openings 226 and 227.

In the second layer 220, a part of the combustor 23 (a part of the combustion chamber 23a) and the reformer 22 are disposed.
The reformer 22 reforms the fuel gas to generate a reformed gas. The reformer 22 includes side plates 203 to 205, partition plates 207, 208, and 221 and a reforming catalyst filled in the space. Composed.

  The reforming catalyst is for reforming the fuel gas, that is, for reforming the fuel gas into a hydrogen-rich fuel gas. For example, a heat-resistant material such as a pressed body of fine metal nickel and ceramic powder or alumina. It is a catalyst in which metallic nickel is supported on a high porous body. For example, ruthenium may be employed as the reforming catalyst in addition to metallic nickel.

  Fuel gas flows into the reformer 22 from the pipe 291 and the opening 226. The fuel gas advances meandering by the partition plates 222 to 224 in the reformer 22 and is reformed by the catalyst. The reformed fuel gas flows into the fuel cell stack 100 through the opening 227, the pipe 292, the members 70 and 60.

  Here, points on the flow path of the fuel gas (path points, first to second paths through which the fuel gas before power generation circulates in order) Q3 to Q1 are arranged corresponding to the above-described merge points P1 to P3. The In other words, the merge points P <b> 1 to P <b> 3 are arranged from the downstream to the upstream of the flow path of the reformer 22. This is to make the exothermic reaction at the junction points P1 to P3 correspond to the endothermic reaction at the path points Q3 to Q1. The endothermic reaction in the flow path of the fuel gas is larger in the upstream with more unreacted gas components, and becomes smaller as it goes downstream. For this reason, by arranging the junction points P1 to P3 where the heat generation amount increases in order corresponding to the path points Q3 to Q1, the exothermic reaction at the junction points P1 to P3 can be canceled and the temperature can be made uniform.

  As shown in FIG. 9, the third layer 230 is partitioned by partition plates 231 to 235. In the third layer 230, the side plate 205 is provided with an opening 236 that communicates with the inside of the protrusion 240 and has a net.

A part of the combustor 23 (combustion chamber 23b) is disposed in the third layer 230.
The combustor 23 burns a mixed gas and is divided into combustion chambers 23a and 23b.
The combustion chamber 23 a is disposed in the first layer 210 to the second layer 220 and includes an upper plate 201, side plates 203, 205 and 206, and partition plates 216 and 221. The combustion chamber 23 b is disposed in the third layer 230, and includes a bottom plate 202, side plates 203 to 205, and a partition plate 208, and is partitioned by partition plates 231 to 235.

  In the third layer 230, the protrusion 240 is connected to the side plate 205. The protrusion 240 has an upper plate, a bottom plate, and three side plates, and is connected to the pipe 293. As described above, the protrusion 240 communicates with the combustion chamber 23b through the opening 236.

  The mixed gas sequentially flows from the opening 219 into the combustion chambers 23a and 23b. The mixed gas advances in the −Z direction in the combustion chamber 23a and flows into the combustion chamber 23b. In the combustion chamber 23b, it advances meandering with the partition plates 231-235. The mixed gas burns and generates heat by the combustion catalyst in the combustion chambers 23a and 23b. The burned mixed gas is discharged to the outside through the opening 236 and the pipe 293.

  As a combustion catalyst, a noble metal catalyst such as platinum, rhodium or palladium can be used. However, it is preferable to use a perovskite oxide because it improves heat resistance and long-term durability. As a carrier for the combustion catalyst, a general cordierite honeycomb carrier or a ferritic stainless steel used as a carrier for an exhaust gas treatment catalyst for automobiles can be used. In particular, when emphasizing startability, the metal carrier is superior in thermal conductivity and thermal shock resistance. However, ceramic carriers are advantageous in terms of durability at high temperatures, and it is desirable to use them properly according to requirements.

  The heating element 300 is, for example, a planar combustion type gas burner for heating the auxiliary device 200 at startup. At startup, the catalyst in the auxiliary device 200 can be activated quickly.

  FIG. 10 is a perspective view showing a third layer 230a according to a modification. A partition plate 238 having guides G1, G2 is disposed in the combustion chamber 23b of the third layer 230a, and honeycomb catalysts Ca, Cb are disposed on both sides thereof.

The honeycomb catalysts Ca and Cb are opened on the mixed gas inflow side (in this example, the X axis direction plus side) and outflow side (in this example, the X axis direction minus side) surfaces, and are separated from each other by partition walls. Having a large number of cells (honeycomb structure). The shape of the cell is, for example, a hexagonal prism shape. A catalyst is fixedly disposed on the inner surface (partition wall) of the cell. When the mixed gas passes through the cells of the honeycomb catalysts Ca and Cb, combustion is promoted by the catalyst.
In this case, the arrangement of the net in the opening 236a can be omitted. This is because, in the honeycomb catalysts Ca and Cb, the combustion catalyst is fixed in the cell, so that it does not flow in the gas flow unlike the pellet type catalyst.
Here, two honeycomb catalysts Ca and Cb are arranged in the third layer 230a, but the number can be appropriately changed to 1, or 3 or more.

  The partition plate 238 and the guides G1 and G2 are used for positioning the honeycomb catalysts Ca and Cb. However, the honeycomb catalysts Ca and Cb may be disposed without using the partition plate 238 and the guides G1 and G2.

  In the present embodiment, the inlet (inflow hole 276) of the remaining oxidant gas (cathode exhaust gas and air) to the mixer 21 is divided into two or more (here, three), and the width of each inlet ( By adjusting the widths d1 to d3) and the introduction path, the remaining fuel gas (anode exhaust gas) in the mixer 21 and the remaining oxidant gas mixing sites (merging points P1 to P3) and the mixing ratio are controlled. , Control the combustion state of the mixed gas.

  Dispersing the mixing parts into a plurality reduces the local combustion violently and prevents the mixer 21 from deteriorating. That is, the remaining oxidant gas is divided and mixed with the remaining fuel gas in stages, so that the combustion is completed at the initial stage when the remaining fuel gas is low, and then the dilution is performed with the oxidant gas. It will only be On the other hand, when there is a large amount of remaining fuel gas, the oxidant gas is divided and sent in stages, and thus burns as much as the divided oxidant gas. Further, the combustion proceeds by the amount of the oxidant gas introduced in the second and third times. In other words, combustion proceeds according to the oxidant gas rule, combustion is dispersed, and combustion heat is dispersed and generated, so that the peak temperature is lowered.

  Combustion is controlled by the number and ratio of the oxidant gas divisions, so that an optimal combustion state can be obtained even in the operation region. That is, if the oxidant gas is divided into two parts, for example, and the ratio of the first mixing and the second mixing is set to 1: 2, the amount of air mixes with less air at the first mixing, so that the state of oxygen deficiency is limited and combustion is limited. Combustion is completed using the remaining air during the second mixing. By doing so, it is possible to disperse combustion sites and control combustion.

  Moreover, since the mixing part of combustion gas and oxidant gas can be controlled, the heat by combustion can be effectively transferred to the adjacent heat absorber. That is, the point at which the oxidant gas is finally added is arranged on the upstream side of the reformer 22, so that the combustion peak temperature can be efficiently used for reforming.

  In this embodiment, the reason why the oxidant gas is divided instead of the remaining combustion gas is that the ease of control is taken into consideration. If the oxidant gas is cathode exhaust gas, the flow rate is overwhelmingly large and easy to control hardware. (Cathode air flows 10 to 20 times the anode fuel in terms of fuel cell input flow rate ratio)

(Comparative example)
A comparative example of the present invention will be described. FIG. 11 is a perspective view showing the inside of the first layer 210x of the auxiliary device 200x of the fuel cell according to the comparative example, and corresponds to FIG.

The mixer 21x is disposed in the first layer 210x. The mixer 21x is partitioned by partition plates 211x to 214x and 218x. An opening 219x having a net is installed in the partition plate 218x.
In the mixer 21x, the remaining fuel gas from the inflow hole 266 and the remaining oxidant gas from the inflow hole 276 are not separated and merge at the junction P0. That is, the remaining oxidant gas from the inflow hole 276 travels along the partition plate 211x and is mixed with the remaining fuel gas at the junction P0 immediately before the inflow hole 276. The mixed gas advances meandering by the partition plates 212x to 214x, and is discharged from the opening 219x to the combustor 23a.

  As described above, in the first embodiment, the remaining oxidant gas is divided into three divided gases F1 to F3 and mixed with the remaining fuel gas at the junctions P1 to P3. On the other hand, in the mixer 21x, the remaining oxidant gas and the remaining fuel gas are mixed at one junction point P0. For this reason, the combustion amount (heat generation amount) at the junction point P0 becomes larger than the combustion amount (heat generation amount) in the other region of the mixer 21x, and it becomes difficult to ensure the uniformity of combustion.

(Second Embodiment)
A second embodiment of the present invention will be described. FIG. 12 is a perspective view showing the inside of the first layer 210a of the auxiliary device 200a of the fuel cell according to the second embodiment, and corresponds to FIG.

  A mixer 21a is disposed in the first layer 210a. The mixer 21a is partitioned by partition plates 211a to 213a and 218. The partition plate 218 is provided with an opening 219 having a net.

  In the mixer 21a, the remaining oxidant gas from the inflow hole 276 is divided into the division gases F1 and F2 by the partition plate 212a, and merges with the remaining fuel gas at the merge points P11 and P12. That is, the remaining oxidant gas from the inflow hole 276 travels along the partition plate 211a and is mixed with the segment gas F1 at the junction P11 immediately before the inflow hole 276. The gas mixed at the junction P11 travels between the partition plates 211a and 212a, and is mixed with the segment gas F2 at the junction P12. The gas mixed at the junction P12 travels between the partition plate 213a and the side plate 203 and is discharged from the opening 219 to the combustor 23a.

  In the second embodiment, the remaining oxidant gas is divided into two and mixed with the remaining fuel gas at the junctions P11 and P12. Similar to the first embodiment, by dispersing a plurality of mixing sites, local combustion is reduced and deterioration of the mixer 21 is prevented.

Here, the flow rates of the division gases F1 and F2 can be increased stepwise.
At this time, the uniformity of temperature at the junctions P11 and P12 can be improved by making the junctions P11 and P12 correspond to the downstream and upstream of the flow path of the reformer 22, respectively.

(Third embodiment)
A third embodiment of the present invention will be described. FIG. 13 is a perspective view showing the inside of the first layer 210b of the auxiliary device 200b of the fuel cell according to the third embodiment, and corresponds to FIG.

  A mixer 21b is disposed in the first layer 210b. The mixer 21b is partitioned by partition plates 211b to 215b and 218. The partition plate 218 is provided with an opening 219 having a net.

  In the mixer 21b, the remaining fuel gas from the inflow hole 266 is divided into three divided gases O1 to O3 by the three openings 211ba to 211bc of the partition plate 211b, and merges at the merge points P21 to P23. That is, the remaining oxidant gas from the inflow hole 276 travels along the partition plate 213b and is mixed with the segment gas O1 at the junction P21 immediately before the opening 211ba. The gas mixed at the junction P21 meanders by the partition plates 213b, 214b, and 215b, and is mixed with the segment gas O2 at the junction P22 just before the opening 211bb. The gas mixed at the junction P22 travels between the partition plates 211b and 215b, and is mixed with the segment gas O3 at the junction P23 just before the opening 211bc. The gas mixed at the junction P23 travels between the partition plate 215a and the side plate 203 and is discharged from the opening 219 to the combustor 23a.

  In the third embodiment, the remaining fuel gas is divided into three and mixed with the remaining oxidant gas at the junctions P21 to P23. Similar to the first embodiment, by dispersing the mixing sites in a plurality, the local combustion is drastically reduced and deterioration of the mixer 21 is prevented. In other words, even if the remaining fuel gas is divided in place of the remaining oxidant gas, local combustion is reduced and deterioration of the mixer 21 is prevented.

Here, the flow rates of the division gases O1 to O3 can be increased stepwise.
At this time, the uniformity of temperature at the junctions P21 to P23 can be improved by making the junctions P21 to P23 correspond to the downstream, middle, and upstream of the flow path of the reformer 22.

(Fourth embodiment)
A fourth embodiment of the present invention will be described. FIG. 14 is a perspective view showing the inside of the first layer 210c of the auxiliary device 200c of the fuel cell according to the fourth embodiment, and corresponds to FIG.

A mixer 21c is disposed in the first layer 210c. The mixer 21c is partitioned by partition plates 211c to 217c and 218. An opening 219 is provided in the partition plate 218.
In the mixer 21c, the remaining oxidant gas from the inflow hole 276 is divided into three gas segments F1 to F3 by the partition plates 212c and 213c. Further, the remaining fuel gas from the inflow hole 266 is divided into three gas segments O1 to O3 by the three openings 211ca to 211cc of the partition plate 211c.

  The division gases F1 to F3 and O1 to O3 merge at the merge points P31 to P35. That is, the section gas F1 travels along the partition plate 212c and is mixed with the section gas O1 at the junction P31 immediately before the opening 211ca. The gas mixed at the junction P31 travels between the partition plates 212c and 215c, and is mixed with the segment gas F2 at the junction P32. The gas mixed at the junction P32 travels between the partition plates 213c and 215c, and is mixed with the segment gas O2 at the junction P33 just before the opening 211cb. The gas mixed at the junction P33 travels between the partition plates 213c and 216c, and is mixed with the segment gas F3 at the junction P34. The gas mixed at the junction P34 travels between the partition plates 216c and 217c, and is mixed with the segment gas O3 at the junction P35 just before the opening 211cc. The gas mixed at the junction P35 travels between the partition plate 217c and the side plate 203 and is discharged from the opening 219 to the combustor 23a.

  In the fourth embodiment, the remaining oxidant gas and fuel gas are both divided into three and mixed at the junctions P31 to P35. Dispersing the mixing parts into a plurality reduces the local combustion violently and prevents the mixer 21 from deteriorating. By separating both the oxidant gas and the fuel gas, the local combustion is more effectively reduced, and the deterioration of the mixer 21 is prevented.

Here, the flow rates of the segment gases F1 to F3 and the segment gases O1 to O3 can be increased stepwise.
At this time, the uniformity of temperature at the junction points P31 to P35 can be improved by making the junction points P31 to P35 correspond to the upstream side to the upstream side of the flow path of the reformer 22.

(Other embodiments)
Embodiments of the present invention are not limited to the above-described embodiments, and can be expanded and modified. The expanded and modified embodiments are also included in the technical scope of the present invention.

  In the first to fourth embodiments, (1) three oxidant gases, (2) two oxidant gases, (3) three fuel gases, and (4) oxidant gas. Both oxidant gas and oxidant gas are divided into three and mixed. That is, it can be seen that the uniformity of the temperature in the mixer 21 can be secured by dividing one or both of the oxidant gas and the oxidant gas into a plurality and mixing them.

DESCRIPTION OF SYMBOLS 10 Fuel cell system 20 Solid oxide fuel cell 21 Mixer 22 Reformer 23 Combustor 23a, 23b Combustion chamber 30 Control part 100 Fuel cell stack 150 Fuel cell 200 Auxiliary device 300 Heating body

Claims (9)

A first inflow section into which a first gas that is one of the remaining fuel gas after power generation in the fuel cell and the remaining oxidant gas after power generation flows;
A second inflow portion into which a second gas that is the other of the remaining fuel gas and the remaining oxidant gas flows;
A dividing section for dividing the first gas flowing in from the first inflow section into two or more;
A first mixing section that mixes and burns a part of the first gas sectioned by the section section and the second gas flowing in from the second inflow section;
A second mixing section for mixing and burning the exhaust gas after combustion in the first mixing section and the other part of the divided first gas;
A fuel cell auxiliary device comprising: The amount of the first gas flowing into the first mixing unit from the dividing unit is smaller than the amount of the first gas flowing into the second mixing unit from the dividing unit. 1. The fuel cell auxiliary device according to 1. The fuel cell further includes a reformer that is disposed corresponding to each of the second and first mixing sections and has first and second paths through which fuel gas before power generation sequentially flows, and reforms the fuel gas. The fuel cell auxiliary device according to claim 2. The dividing section divides the first gas flowing in from the first inflow section into three or more;
A third mixing section for mixing and burning the exhaust gas after combustion in the second mixing section and a further part of the first gas sectioned in the section section;
The third mixing unit mixes and combusts the exhaust gas after combustion in the second mixing unit and another part of the first gas sectioned in the section section. Item 3. The fuel cell auxiliary device according to any one of Items 1 or 2. The fuel cell system further includes a reformer disposed corresponding to each of the third to first mixing sections and having first to third paths through which fuel gas before power generation flows in order, and reforming the fuel gas. The fuel cell auxiliary device according to claim 4. The first gas is the residual oxidant gas and the second gas is the residual fuel gas;
The fuel cell auxiliary device according to any one of claims 1 to 5, wherein the auxiliary device is a fuel cell. The first gas is the residual fuel and the second gas is the residual oxidant gas;
The fuel cell auxiliary device according to any one of claims 1 to 5, wherein the auxiliary device is a fuel cell. A second section that separates the second gas flowing in from the second inflow section into two or more;
The first mixing part mixes and burns a part of the first gas divided by the dividing part and a part of the second gas divided by the second dividing part;
The second mixing section includes exhaust gas after combustion in the first mixing section, another part of the first gas sectioned in the section section, and another section sectioned in the second section section. Part of the second gas is mixed and burned,
The fuel cell auxiliary device according to any one of claims 1 to 3.   A fuel cell comprising the fuel cell auxiliary device according to claim 1.

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