JP5172263B2 - Fuel cell power generation system - Google Patents

Description

  The fuel cell includes an anode (fuel electrode) on one side with an electrolyte in between, and a cathode (air electrode) on the other side. The power generating element generates electricity by causing an electrochemical reaction (battery reaction) between the fuel in the anode gas flowing on the anode surface and the oxidant in the cathode gas flowing on the cathode surface via the electrolyte. A solid oxide fuel cell, which is one type of fuel cell, is a fuel cell using oxygen ion conductive ceramics as an electrolyte.

  Since the solid oxide fuel cell is made of ceramic, it may be broken by an impact. Therefore, for example, as disclosed in Patent Document 1, in order to protect the fuel cell from shocks such as vibration, the power generation unit is supported by a buffer material made of ceramic fiber or metal fiber. The fuel or air (oxidant) is supplied through the buffer material.

  In order to make the flow rate of the supplied gas uniform, a rectifying layer is provided below the power generation unit. As the rectifying layer, for example, as disclosed in Patent Document 2 and Patent Document 3, a metal or ceramic foam or a ceramic-filled layer is used.

  Further, as disclosed in Patent Document 1, in order to support the contents of the fuel cell and the other power generation unit through the cushioning material and to transmit the gas supplied to the power generation unit, In this case, a ceramic or metal dispersion plate having a hole in a region where the contents do not contact is used.

JP 2005-216579 A JP 2003-100338 A JP 2000-58087 A

  In the above-described conventional technology, when a buffer material in which fibers having sufficient strength are closely entangled is used, the flow resistance of the fuel or oxidant gas is large, so the pressure loss is large, and a large power is required for gas supply. Was necessary.

  In addition, the rectifying layer is thick, which hinders the compactness of the power generation system.

  An object of the present invention is to provide a support mechanism for a power generation unit of a fuel cell in which pressure loss in supplying fuel or oxidant gas is reduced.

  Another object of the present invention is to provide a support mechanism for a power generation unit of a fuel cell that is compact and can exhibit sufficient buffering, rectification, distribution, and support functions.

  In one aspect of the present invention, a plurality of fuel cells having an anode and a cathode on both sides via an electrolyte, a fuel flow channel adjacent to the anode surface in the power generation unit, an air flow channel adjacent to the cathode surface, and the power generation In a fuel cell power generation system provided with a shock absorber that is disposed in an introduction part or a discharge part of fuel or air to a part and cushions and supports a plurality of the fuel cells, a previous fuel flow path or air around the plurality of fuel cells The flow path is characterized in that the flow resistance of a part or all of the flow path projection area of the buffer material projected in the flow path direction is made smaller than the other areas of the buffer material.

  In a preferred embodiment of the present invention, a vent is provided in a part of the flow path projection region of the cushioning material.

  In a preferred embodiment of the present invention, a rectifying layer is provided in close contact with the buffer material.

  Furthermore, in a preferred embodiment of the present invention, a support structure formed of a lattice-like or honeycomb-like metal or ceramic is disposed in close contact with the rectifying layer.

  In another aspect of the present invention, the fuel flow path or the air flow path around the plurality of fuel cells has a flow resistance of a part or all of the flow path projection region of the rectification layer projected in the flow path direction. It is characterized by being smaller than the other areas of the layer.

  In still another aspect of the present invention, in the fuel cell power generation system including the rectifying layer that regulates the flow of the fuel or air, and the support structure of the power generation unit, the buffer material, the rectification layer, and the support structure include: As seen from the power generation unit, the buffer material, the rectifying layer, and the support structure are arranged in this order.

  In a preferred embodiment of the present invention, a plurality of fuel cells having an anode outside a bag tube cylindrical electrolyte and a cathode inside, a fuel flow channel adjacent to the anode surface in the power generation unit, and the bag tube cylinder In a fuel cell power generation system including an air flow path adjacent to a cathode surface on the inner side of an electrolyte of a shape and a buffer material disposed in a fuel introduction portion to the power generation portion and buffering and supporting the plurality of fuel cells. The fuel flow path around the fuel cell is arranged in close contact with the vent hole disposed in a part of the flow path projection region of the buffer material projected in the flow path direction and the fuel introduction side of the buffer material And a support structure that is disposed in close contact with the fuel introduction side of the rectifying layer and is formed of a lattice-like or honeycomb-like metal or ceramic.

  According to a preferred embodiment of the present invention, in the buffer material that forms a substantially right-angle plane in the gas flow path, preferably, a flow hole is provided in the flow path projection buffer material region to reduce the flow resistance. Pressure loss can be reduced.

  Further, according to a preferred embodiment of the present invention, the gas supplied to the power generation unit easily flows in the rectifying layer flow path projection area, the flow velocity in the rectifying layer flow path projection area is increased, and the rectifying layer is thinned. Can obtain the same rectifying effect.

  Moreover, according to the desirable embodiment of this invention, it can be set as the support structure with a large opening area, supporting the electric power generation part planarly, and the pressure loss in a support structure can be reduced.

  Other features of the present invention will become apparent from the embodiments described below.

  Solid oxide fuel cells are roughly classified into a cylindrical shape and a plate shape depending on the shape of the electrolyte, but the present invention can be applied to either shape. Hereinafter, the fuel cell will be described in detail taking a bag tube cylindrical fuel cell as an example.

  FIG. 1 is a schematic side sectional view of a power generation system including a bag tube cylindrical solid oxide fuel cell according to Embodiment 1 of the present invention. Although the fuel cell 1 in this embodiment is described as having a cathode on the inner surface and an anode on the outer surface, the present invention can be applied to a type in which the positions of the cathode and the anode are reversed.

  2 is a cross-sectional view taken along line AA in FIG. 1, FIG. 3 is a cross-sectional view taken along line BB in FIG. 1, and FIG. 4 is a cross-sectional view taken along line CC in FIG. 5 is an exploded perspective view of the cushioning material 5, the rectifying layer 6 and the support structure 7 in FIG. Below, with reference to FIGS. 1-5, the electric power generation system provided with the solid oxide fuel cell by Example 1 of this invention is demonstrated.

  In this embodiment, the plurality of fuel cells 1 are electrically connected to each other by a current collecting member 2 at the center in the vertical direction as shown in a cross section in FIG. A space called a power generation unit 21 is formed. In the gas seal container 3, an electrical insulating material 4 is housed for electrical insulation between the gas seal container 3 and the fuel cell 1 and between the gas seal container 3 and the current collecting member 2. The gas seal container 3 serves to seal the fuel 31 supplied to the outside of the fuel cell 1. A space 24 in the power generation unit 21 in FIG. 2 forms a fuel flow path.

  The fuel 31 is supplied to the power generation unit 21 from a space called a fuel supply chamber 22 disposed below the power generation unit 21. In the power generation unit 21, after flowing upward in the power generation unit fuel flow path 24 which is a space surrounded by the gas seal container 3 outside the fuel cell 1 and causing an electrochemical reaction in the anode outside the fuel cell 1, It flows through the partition plate 7 and flows into a space called a fuel chamber 23. The partition plate 7 is made of a plate material having a hole or a porous body so that gas can permeate.

  The air 32 is supplied to the air header 5 above the fuel cell, supplied from the air introduction pipe 6 to the bottom of the fuel cell 1, reverses direction, and flows upward through the cathode inside the fuel cell 1, where an electrochemical reaction occurs. The remaining air flows into a space called the combustion chamber 23.

  In the combustion chamber 23, the fuel 31 and the air 32 that have not electrochemically reacted are combusted, and the gas after combustion is discharged as an exhaust gas 33 and is recovered as exhaust heat.

  Below the bottom surface of the combustion cell 1, a structure constituting the main part of the present invention is provided. First, a buffer material 8 is provided to protect the bottom of the fuel cell. The buffer material 8 is made of ceramic or metal fiber. The shock-absorbing material 8 is planarly arranged over almost the entire horizontal section of the power generation unit 21.

  As clearly shown in FIG. 3, the plane of the buffer material 8 is composed of a region 81 projected in the flow direction by the fuel flow passage 24 in the power generation unit and a region 82 projected in the flow direction by the fuel cell 1. However, a vent hole 83 is provided in the projection region 81 formed by the fuel flow path 24 in the power generation section. Since there is no fuel cell 1 to be supported in the projection region 81 formed by the fuel flow path 24 in the power generation section, no interference function is required, and the fuel 31 is supplied to the power generation section 21 through the vent 83 preferentially. For this reason, the pressure loss in the buffer material 8 can be reduced without impairing the buffer function.

  Further, it is possible to control the flow rate of the fuel distributed to each fuel cell 1 by adjusting the area of the vent 83. There is no gas flow resistor between the vent 83 and the fuel cell 1, and the fuel can be distributed directly to the fuel cell 1.

  As described above, in this embodiment, the flow resistance of a part of the flow path projection region 81 of the buffer material 8 projected in the gas flow path direction is provided by providing the air holes 83, so that It is smaller than the region 82.

  The rectifying layer 9 is disposed closely adjacent to the lower side of the buffer material 8, and uniformizes the flow rate of the fuel 31 flowing into the vent hole 83 of the buffer material 9. The material of the rectifying layer 9 is a porous body made of ceramic or metal, and a rigid porous body is used so that the periphery can be easily sealed. Foams that are rigid and have a high inertial resistance to gas flow are particularly suitable for the rectifying layer.

  FIG. 4 is a cross-sectional view of the support structure 10. As the material of the support structure 10, a metal or ceramic plate is used, and these are assembled in a lattice shape. The support structure 10 may have a honeycomb shape. In this embodiment, the rectifying layer 9 receives the fuel cell 1 on the average through the buffer material 8. Further, since the rectifying layer 9 is rigid, the support structure 10 only needs to have sufficient strength to support the power generation unit 21 and can have a sufficiently wide opening area as a gas flow path. Thereby, the pressure loss in the support structure 10 can be significantly reduced.

  It is desirable that the lattice portion of the support structure 10 does not overlap with the lower portion of the vent hole 83. The size of the opening portion of the support structure 10 is determined according to the strength of the rectifying layer 9.

  FIG. 5 shows an exploded perspective view of a structure including the buffer material 8 for buffering and supporting the fuel cell group described above, the rectifying layer 9 and the support structure 10.

  First, the rectifying layer 9 is closely mounted on the lattice structure of the support structure 10. Therefore, it is sufficient that the rectifying layer 9 using a ceramic or metal porous body has a thickness that can perform the function of rectifying the gas without causing a burden on the strength.

  Further, a buffer material 8 is disposed in close contact with the rectifying layer 9. Since the fuel is distributed to each fuel cell 1 through the vent holes 83 formed in the buffer material 8, the flow rate of the fuel flowing through the vent holes 83 is uniform in the rectifying layer 9 installed in close contact with the buffer material 8. You just have to. As described above, the vent 83 is provided in the projection region 81 of the power generation unit fuel flow path 24 in the plane of the cushioning material 8. The fuel flow here will be described with reference to FIG.

  FIG. 6 is a flow diagram of the fuel inside the rectifying layer 9 in the first embodiment. As shown in the figure, the rectifying layer 9 is installed in close proximity to the cushioning material 8 having the air holes 83, so that the gas in the rectifying layer 9 flows preferentially below the air holes 83. . Accordingly, the flow rate of the fuel flowing in the rectifying layer 9 below the vent hole 83 is increased. As a result, the pressure loss generated per unit thickness of the rectifying layer 9 below the vent hole 83 increases, and thereby the rectifying effect can be sufficiently exhibited even if the rectifying layer 9 is relatively thin.

  FIG. 10 shows a fine structure of the rectifying layer cross section and a gas stream line flowing through the rectifying layer. Since the rectifying layer 9 uses a porous body, it has many fine through holes, and gas flows through the holes. In this embodiment, since the rectifying layer 9 and the buffer material 8 having the air holes 83 are arranged in close contact with each other, gas does not flow so much at the portion where the hole outlet of the rectifying layer 9 is in contact with the buffer material 8, The outlet mainly flows through a portion of the cushioning material 8 communicating with the vent 83. Therefore, in order to make the gas flow rate flowing from each vent hole uniform, it is important that the cross-sectional area of the rectifying layer hole outlet (lower vent rectifying layer hole) overlapping with the vent hole 83 is uniform.

  FIG. 11 shows the relationship between the vent hole diameter, the rectifying layer hole diameter, and the rectifying layer hole pitch. When the vent hole diameter D is the same as the distance between the centers of the rectifying layer holes (diameter d) ((rectifying hole pitch p) (D / p = 1 to 2 times)), the lower rectifying layer hole depending on the vent hole installation position That is, in order to make the gas flow rate flowing from each vent hole uniform, the vent hole diameter D / rectifying plate hole pitch p must be sufficiently large, but the appropriate D / p is Depending on the ratio of the diameter d of the rectifying plate holes to the rectifying plate hole pitch p, the arrangement of the rectifying layer holes varies as shown in FIG. D / p needs to be large enough to make it uniform, and the actual rectifying layer uses a material with a porosity d / p of about 0.6 to 1 from the viewpoint of strength and flow resistance, about 10% In an experiment using such a material, D / p = 4 times or more is necessary, and 8 In addition, when the current plate hole diameter is extremely small, the flow resistance of the current flow layer is increased, so the current plate hole diameter should be selected in a range where D / p> 4-8. There is a need.

  In addition, when the opening ratio of the vent hole 83 in the buffer material 8 (cross-sectional area of the vent hole / total cross-sectional area of the buffer material including the vent hole) is too large, the fuel flowing in the rectifying layer 9 below the vent hole 83 The effect of increasing the flow rate is lost. In addition, when the opening rate of the vent 83 is too small, the flow rate of the fuel supplied from the vent 83 to the fuel cell becomes too high, causing an uneven flow in the fuel flow path to the fuel cell 1. End up. In order to avoid these events, it is desirable that the opening ratio of the vent 83 is 2% to 20%.

  FIG. 7 shows streamlines in the rectifying layer 9 according to the second embodiment of the present invention. In this embodiment, the rectifying layer 9 is embedded in the vent hole 83 of the buffer material 8. Thereby, the buffer material 8 and the rectification | straightening layer 9 can be integrated, and it can make compact. In addition, the buffer material 8 needs to set flow resistance remarkably higher than the rectifying layer 9.

  FIG. 8 shows streamlines in the rectifying layer 9 according to the third embodiment of the present invention. In this embodiment, the porosity of the rectifying layer 9 is large at the lower portion 91 of the vent 83 of the buffer material 8 and is small at the other region 92. As a result, the fuel 31 flows preferentially below the vent 83 and the rectifying effect per thickness of the rectifying layer 9 is increased. The same effect can be obtained even when the buffer material 8 is not in close contact with the rectifying layer 9 or when the buffer material 8 is not present.

  FIG. 9 is a plan sectional view showing the arrangement of the vent holes 831 to 833 of the cushioning material 8 according to the fourth embodiment of the present invention.

  During power generation, the fuel cell 1 generates heat due to internal resistance, and the fuel cell 1 is maintained by cooling the fuel cell 1 with air 32 and fuel 31. However, when all the fuel cells in the power generation unit 21 are cooled by the same method, the cells inside the power generation unit 21 have a smaller heat dissipation amount than the outer cells, and thus easily become high temperature.

  Therefore, as shown in FIG. 9, the flow rate of fuel supplied to the inner fuel cell 1 can be increased by making the cross-sectional area of the inner vent hole 831 larger than that of the outer vent holes 832 and 833, and the inner fuel cell can be increased. The cooling amount can be made larger than that of the outer fuel cell to reduce the temperature distribution. The flow rate distribution of fuel supplied to the inner and outer fuel cells can be freely designed by the cross-sectional area distribution of the vent holes 831 to 833.

1 is a schematic side sectional view of a power generation system including a solid oxide fuel cell according to Example 1 of the present invention. AA sectional drawing of FIG. BB sectional drawing of FIG. CC sectional drawing of FIG. The disassembled perspective view of a buffer material, a rectification | straightening layer, and a support structure. FIG. 3 is a streamline diagram of fuel in the rectifying layer in the first embodiment. FIG. 4 is a cross-sectional structure of a buffer material and a rectifying layer and a fuel flow diagram in Example 2. FIG. 6 is a cross-sectional structure of a cushioning material and a rectifying layer and a fuel flow diagram in Example 3. FIG. 6 is a plan sectional view showing the arrangement of the ventilation holes of the buffer material in Example 4. FIG. 3 is a streamline diagram showing gas flow lines flowing through the rectifying layer in the first embodiment. Explanatory drawing which shows the relationship between a vent hole diameter, a rectifying layer hole diameter, and a rectifying layer hole pitch. Explanatory drawing which shows the dispersion | variation in a rectification | straightening layer hole.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 1 ... Fuel cell, 2 ... Current collecting member, 3 ... Gas seal container, 4 ... Electric insulation board, 5 ... Air header, 6 ... Air introduction pipe, 7 ... Partition plate, 8 ... Buffer material, 81 ... Fuel flow path Projected buffer material region, 82... Buffer material region projected onto the fuel cell, 83, 831 to 833... Ventilation hole, 9 ... Rectification layer, 10 ... Support structure, 21 ... Power generation unit, 22 ... Fuel supply chamber, 23 ... combustion chamber, 24 ... fuel flow path in power generation section, 31 ... fuel, 32 ... air, 33 ... exhaust gas.

Claims (4)

  A plurality of fuel cells having an anode and a cathode on both sides via an electrolyte; a fuel flow path adjacent to the anode surface in the power generation unit; an air flow path adjacent to the cathode surface; and fuel or air to the power generation unit In the fuel cell power generation system provided with a cushioning material that is disposed in the introduction part or the discharge part and cushions and supports the plurality of fuel cells, the fuel channel or the air channel around the plurality of the fuel cells includes the channel. A flow rectifying layer arranged in close contact with the buffer material, wherein a part or all of the flow path projection region of the buffer material projected in the direction has a smaller flow resistance than other regions of the buffer material, The material and the rectifying layer are closely arranged in the order of the buffer material and the rectifying layer when viewed from the power generation unit, and a ventilation hole is provided in a part of the flow path projection region of the buffer material, and the rectifying layer is porous The vent hole diameter Fuel cell power generation system characterized by serial to four times more holes pitch of the rectifying layer. 2. The fuel cell power generation system according to claim 1, wherein a support structure formed of a lattice-like or honeycomb-like metal or ceramic is disposed in close contact with the outside of the rectifying layer. 2. The fuel cell power generation system according to claim 1, wherein an opening ratio of the vent hole in the cushioning material is 2 to 20%. 2. The fuel cell power generation system according to claim 1, wherein the rectifying layer is formed of a ceramic or metal foam.

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