JP2008166233A - Fuel cell - Google Patents

Abstract

An object of the present invention is to provide a fuel cell that can improve efficiency after being made compact and has excellent controllability when a load fluctuates or starts and stops.
SOLUTION: A reformer 40 having a reforming channel 41 carrying a catalyst for reforming a fuel gas F, and an introduction hole 21 of a fuel gas F that holds a single cell 6 and is reformed by the reformer 40. And a cell plate 2 having a discharge hole 22 and a separator plate 3 having a fuel gas F introduction hole 31 and a discharge hole 32 and having an outer edge joined to the outer edge of the cell plate 2. A stack structure 11 formed by stacking a plurality of units 1, a gas introduction unit 12 a and a gas discharge unit 12 b, and a case 12 that introduces air Ai and exhausts between the solid oxide fuel cell units 1. The reformer 40 is positioned in the exhaust flow of the air Ai passing between the electrolyte fuel cell units 1, and heat exchange is performed with the fuel gas F passing through the reforming flow path 41.
[Selection] Figure 1

Description

    The present invention relates to a fuel cell including a reformer that reforms fuel gas and a stack structure formed by stacking a plurality of solid oxide fuel cell units.

  Conventionally, as the fuel cell as described above, for example, a cylindrical stack structure in which circular separators and cell plates are alternately stacked, and a spiral shape along the outer peripheral edge of the stack structure. In some fuel cells, the fuel gas is supplied from the reforming catalyst tube to the fuel electrode side of the cell plate through the central portion of the separator and used for power generation. The remaining fuel gas and air that have not been used for power generation are discharged from the outer peripheral edge of the cell plate and mixed and burned.

In other words, in this fuel cell, by setting the reforming catalyst pipe in the combustion field with the vicinity of the outer peripheral edge of the cell plate as the combustion field, the amount of heat necessary for reforming is provided to the reforming catalyst pipe. It has become.
JP 2005-019034 A

  However, in the fuel cell described above, the reforming catalyst tube is spirally arranged along the outer peripheral edge of the stack structure, so that the size can be reduced, but the load may fluctuate greatly or start / stop When the power generation output fluctuates abruptly, for example, the combustion starts suddenly due to a sudden change in the flow rate of the supplied fuel gas or air, and a phenomenon in which fire is drawn between the separator and the cell plate, so-called There has been a problem that a backfire is generated, which may cause deterioration of the cell.

  Also, if the temperature of the reforming catalyst tube rises too much due to combustion in the combustion field in the vicinity of the outer peripheral edge of the cell plate, the performance of the reforming catalyst may be deteriorated. The problem is that it is difficult to simultaneously control the amount of fuel gas supplied for power generation, the amount of heat generated for reforming, and the temperature of the reforming catalyst tube at that time, such as when the load fluctuates or starts and stops. There has been a conventional problem to solve these problems.

  The present invention has been made by paying attention to the above-described conventional problems, and can achieve an improvement in efficiency after being made compact, and has excellent controllability when the load fluctuates or when the engine is started and stopped. The object is to provide a fuel cell.

  The fuel cell according to the present invention includes a reformer having a reforming channel filled or supported with a catalyst for reforming a fuel gas, and a fuel gas and air that is retained by the reformer and holds a single cell. A cell plate having an introduction hole and an exhaust hole for one of the gas, an introduction hole and an exhaust hole for one of the fuel gas and air reformed by the reformer, and an outer edge thereof. A plurality of solid oxide fuel cell units each having a separator plate joined to the outer edge of the cell plate are stacked. One gas is introduced from the introduction hole and exhausted from the discharge hole through each solid oxide fuel cell unit. And the other gas of the fuel gas and air reformed by the reformer is introduced from the gas introduction part in a state of containing the stack structure and containing the stack structure. Solid electrolysis overlapping each other And a stack of solid electrolyte fuel cells having a stack structure, and a gas flowing through the plurality of solid electrolyte fuel cell units of the stack structure. A reformer is positioned in any one of the exhaust streams of the other gas passing between the units, and between the exhaust stream and the fuel gas passing through the reformer flow path of the reformer. Heat exchange is performed, and the configuration of the fuel cell is used as a means for solving the conventional problems described above.

  In the fuel cell of the present invention, the exhaust gas flow of one gas or the other gas that exchanges heat with the fuel gas passing through the reforming flow path of the reformer does not mix with each other. In addition, the unused fuel in the exhaust stream can be mixed with the unreformed fuel gas or the reformed fuel gas introduced into the reformer, and introduced into the stack structure again. Become.

  That is, the exhaust flow of fuel gas containing unused fuel is effectively used according to the operating state, for example, used for starting a fuel cell in the subsequent stage, generating electricity, or introducing it into an exhaust gas purification burner. Therefore, the controllability with respect to the fluctuation of the load becomes good, and the operation can be performed without reducing the fuel utilization rate.

  Since the fuel cell of the present invention has the above-described configuration, it is possible to perform highly efficient operation while realizing a compact size, and in addition, supply of fuel gas necessary for power generation when the load fluctuates or starts and stops. An excellent effect of facilitating simultaneous control of the amount, the calorific value necessary for reforming, and the temperature of the reformer is brought about.

  The solid oxide fuel cell unit of the fuel cell according to the present invention is formed by joining the outer edge portions of the cell plate and the separator plate, and along the outer edge portion at least one of the cell plate and the separator plate. By providing the step, a space for flowing one of the fuel gas and the air is formed between the cell plate and the separator plate.

  Further, in the fuel cell of the present invention, the thickness of the central portion of the solid oxide fuel cell unit is made larger than the thickness of the single cell installation region so as to have a spacer function, thereby stacking the solid oxide fuel cell unit. A flow path for flowing the other of the fuel gas and air is formed between the two layers.

  In addition, if the above steps are formed on both the cell plate and the separator plate so as to be symmetrical with each other, stress concentration can be suppressed, and even if the sizes of both steps are changed mutually. The improvement in strength due to the provision of the step can be expected, and when the step is formed on one of the cell plate and the separator plate, the mounting area of the single cell can be expanded. The shapes of the cell plate and the separator plate can be changed according to characteristics that are important, such as improvement and improvement of output density.

  Furthermore, in the fuel cell of the present invention, it is desirable that the step provided on the cell plate and the separator plate of the solid oxide fuel cell unit is formed by pressing, and for joining the outer edge portions of each of the cell plate and the separator plate, In addition to welding and brazing, an ultrasonic bonding method can also be used.

  Furthermore, in the fuel cell of the present invention, the mounting position of the single cell of the solid oxide fuel cell unit is set in a region between the center portion and the outer edge portion of the cell plate, and one or more single cells are provided in this region. Can be fixed.

  For example, when the single cell has a small-diameter disk shape, it is desirable to regularly arrange the cells around the center of the cell plate. In addition, when the single cell has a donut shape, it is desirable that the inner ring and the outer ring that have been pressed are joined to the inner peripheral edge and the outer peripheral edge, respectively. Further, the inner ring and the outer ring may be connected to form a frame shape, and a fan-shaped single cell may be attached to the frame.

  Furthermore, the fuel cell case of the present invention accommodates a stack structure and a current collector disposed between overlapping solid oxide fuel cell units and a filler that fills a gap between the stack structure. However, by appropriately setting the location and density of these current collectors and fillers, the other gas introduced from the gas introduction unit is installed between the solid oxide fuel cell units and a single cell for this case. It is possible to provide a rectification function that allows the position to flow preferentially.

  Furthermore, in the fuel cell of the present invention, when each cell plate or separator plate of the plurality of solid oxide fuel cell units is made of a conductive material, the space between the solid oxide fuel cell units is not a single cell portion. The case can be provided with an insulating function for preventing an electrical short circuit.

  Furthermore, in the fuel cell of the present invention, when an air exhaust flow is used as an exhaust flow for exchanging heat with the fuel gas passing through the reforming passage of the reformer, for example, it is introduced into the case. It is possible to employ a configuration in which the reforming flow path of the reformer is positioned in the vicinity of the gas discharge part of the case or downstream of the single cell using the other gas as air. It is easy to circulate the exhaust flow of the fuel gas containing the fuel gas while maintaining a high temperature or to supply the exhaust gas to the subsequent fuel cell, so that the fuel utilization rate in the entire system can be improved.

  On the other hand, in the fuel cell of the present invention, when the exhaust flow of the fuel gas is used as the exhaust flow for exchanging heat with the fuel gas passing through the reforming passage of the reformer, for example, A dew condensation water recovery function can be installed at a site to which heat is supplied, and thereby water generated from the exhaust flow of fuel gas accompanying power generation can be recovered with a compact structure.

  In this case, by using a reformer having an inlet for steam and air at the inlet of the reformed gas flow path, a steam reforming mode that is an endothermic reaction and a partial oxidation reforming mode that is an exothermic reaction. It is possible to adjust both the ATR reaction mode (Auto Thermal Reforming) in which these two reactions proceed simultaneously.

  For example, by detecting the gas temperature and gas flow rate for supplying heat to the reformer, and responding to the required output at this stage, the flow rates of fuel gas, water, and air introduced into the reformed gas flow path are adjusted. By adjusting, the reforming reaction mode can be controlled.

  Here, when the required power generation output changes from a small state to a large state, the flow rate ratio of air to fuel gas is increased so that the reaction mode is mainly composed of a partial oxidation reaction that is an exothermic reaction. To do. When the power generation state at the maximum output is continued, the flow rate ratio of the water introduced into the reformed gas flow path is increased to adjust to the reaction mode mainly composed of steam reforming which is an endothermic reaction.

  Furthermore, the fuel cell of the present invention can be used as a fuel by gasifying a main component of hydrocarbon such as methane, propane, butane, or octane. At this time, hydrocarbons containing oxygen such as alcohols such as methanol, ethanol and propanol, ethers such as dimethyl ether, carboxylic acids and aldehydes can be used as fuel. It is expected that the steam reforming can be performed at a temperature lower than the operating temperature.

  Furthermore, in the fuel cell of the present invention, when a liquid fuel is used or when the reformer is operated in the steam reforming mode, a vaporizer is disposed upstream of the reformed gas flow path of the reformer. In this case, the vaporizer part may be integrated into the most upstream part of the reformed gas flow path of the reformer.

  Furthermore, in the fuel cell of the present invention, examples of the catalyst supported in the reformed gas flow path include noble metal (Ru, Rh, Pt, etc.), non-noble metal (Ni, Cu, Fe, Co, etc.), Alternatively, metal oxides (transition metals, alkaline earths, rare earth element oxides or composite oxides thereof) can be used, but are not particularly limited thereto. Further, as the catalyst carrier, oxides such as Al2O3, SiO2, TiO2, ZrO2, and MgO, composite oxides of these, and carbides and nitrides of various elements can be used, but are not particularly limited to these. is not.

  In the reformer gas channel of the reformer, the catalyst and catalyst carrier can be packed in the form of granules, powder, or pellets, and the catalyst is supported on a honeycomb carrier such as cordierite. The honeycomb can be installed in the gas flow path.

  Furthermore, in the fuel cell of the present invention, an activation burner for activating the reformer and the stack structure may be installed. For example, the exhaust flow of the fuel cell air serves as a gas for providing reforming heat. In some cases, an activation burner can be installed on the upstream side of the air flow path introduced into the fuel cell. That is, the air heated by the combustion burner at the time of start-up can be sent to the stack structure, and then the high-temperature air exhaust stream that has passed through the stack structure can be supplied to the reformer side as heat donating gas to be heated.

  Further, the start burner for starting the reformer and the stack structure may be installed upstream of the reformed gas flow path of the reformer. In this case, the high temperature gas generated by the combustion burner is used. The reformer is introduced into the reforming gas flow path of the reformer and heated to start a reaction mode reformer mainly composed of partial oxidation reforming of an exothermic reaction. Then, the reformed gas having a high temperature from the reformer is introduced into the flow path of the fuel gas, and the fuel cell is heated and started.

  Furthermore, in the fuel cell of the present invention, the pressure loss at the stage when any one of the exhaust flow of one gas and the exhaust flow of the other gas passes through the reformer is caused by the plurality of stack structures. It can be set as the structure larger than the pressure loss of the step in which the other gas passes between solid oxide fuel cell units.

  Specifically, the total cross-sectional area of the flow path in the reformer through which the exhaust flow passes is made smaller than the total cross-sectional area between the plurality of solid oxide fuel cell units of the stack structure through which the other gas passes. Therefore, the pressure loss in the reformer part is increased, so that the gas flow rate distribution and the gas flow rate distribution become uniform between the solid oxide fuel cell units in which the single cells are arranged, and the other gas. As a result, the total output in the surface of the solid oxide fuel cell unit is improved.

  At this time, the flow path width of the reformer section is set smaller than the apparent flow path width between the plurality of solid oxide fuel cell units, or a mesh having a low porosity is heated in the flow path of the reformer section. By filling it as an exchange member, the total cross-sectional area of the flow path in the reformer can be made smaller than the total cross-sectional area between the plurality of solid oxide fuel cell units. It becomes easy to adjust the flow distribution, the gas distribution uniformity can be further improved, and the power generation output of the entire stack structure can be improved.

  In addition, by installing heat exchange members such as heat exchange fins in the reformer gas flow path or the gas flow path for supplying heat, or by changing the installation status, For example, in the gas flow path for supplying heat, the number of heat exchange members is increased toward the downstream side so that turbulent flow is likely to occur. You may make it enlarge the pressure loss in a mass part.

  In this way, when heat exchange members such as heat exchange fins are installed in the gas flow path for supplying heat, in addition to achieving uniform power generation output, the heat exchange efficiency in the reformer part is also improved. As a result, the reforming rate of the fuel gas in the reformer is improved and the composition of the reformed gas is stabilized, resulting in poisoning or carbon deposition at the fuel electrode of a single cell. Deterioration is suppressed and durability is improved.

  Furthermore, in the fuel cell of the present invention, the stacking direction of the plurality of solid oxide fuel cell units of the stack structure and the direction of the reforming flow path of the reformer are parallel to each other. For example, a plurality of tubular reforming channels carrying a reforming catalyst are arranged along the stacking direction of the units in a portion from between the plurality of solid oxide fuel cell units to the gas discharge part of the case. Can be adopted.

  In this case, the plurality of reforming channels carrying the reforming catalyst are located in a portion where heat can be exchanged between the case and the stack of the solid oxide fuel cell units that are heated by the power generation. In this case, the fuel gas is introduced into the reformer, reformed in the reformed gas flow path that is the catalytic reaction tube, and then introduced into the stack structure that is the power generation unit. .

  Thus, when the stacking direction of the plurality of solid oxide fuel cell units of the stack structure and the direction of the reforming flow path of the reformer are parallel to each other, the reformer and the stack structure The sensible heat of the exhaust flow can be used for reforming without loss, improving the efficiency, and in addition, the modification located on the downstream side of the air exhaust flow. Since the pressure loss in the mass part is high and a good gas flow can be set easily, even if the gas flow rate changes according to the required power generation output fluctuation, the gas flow uniformity is maintained. It becomes easy to maintain high power generation efficiency.

  Here, in order to improve the heat exchange efficiency and the controllability of pressure loss, it is desirable to form heat exchange fins on the outer periphery of the reformed gas flow path that is a catalytic reaction tube, or to form an uneven shape. In order to obtain the same effect as described above, it is desirable to fill a porous body with adjusted porosity between the case and the reformed gas flow path.

  In addition, the cross-sectional shape of the reformed gas flow path of the reformer that is the catalyst reaction tube is not limited to a circular shape, and may be a square shape or a triangular shape. Assuming that the cross-sectional shape of the reformed gas channel is rectangular, for example, a structure similar to a plate fin type heat exchanger formed by stacking plates, that is, the fuel gas in the reformed gas channel along the plate stacking direction A structure in which the introduction hole and the discharge hole are formed can be employed.

  Furthermore, in the fuel cell of the present invention, the stacking direction of the plurality of solid oxide fuel cell units of the stack structure and the direction of the reforming flow path of the reformer can be orthogonal to each other. For example, the separator plate used in the solid oxide fuel cell unit of the stack structure is joined to form a flat plate unit having a reforming channel inside, and the flat plate unit carrying the reforming catalyst is supported. It is possible to employ a configuration in which a plurality of flat plate units are stacked on the stack structure so that the flow paths and the stacking directions of the plurality of solid oxide fuel cell units of the stack structure are orthogonal to each other.

  In this case, when air as the other gas is introduced into the case containing the flat plate unit and the stack structure stacked on each other, the air introduced through the gas introduction unit is a plurality of solids of the stack structure that is a power generation unit. The air that flows between the electrolyte fuel cell units and becomes a high-temperature exhaust gas flows between the flat plate units. On the other hand, fuel gas is introduced into each of a plurality of flat plate units and reformed, and then introduced into a plurality of solid oxide fuel cell units of a stack structure that is a power generation unit and used for power generation. The

  Thus, when the stacking direction of the plurality of solid oxide fuel cell units in the stack structure and the direction of the reforming channel of the reformer are orthogonal to each other, a structure in which similar units are stacked on each other Therefore, it is possible to freely design the number of stacking stages according to various conditions such as fuel composition, required reforming degree, and power generation output. By controlling the installation pattern of the solid gas flow path, the gas flow between the solid oxide fuel cell units can be made uniform, so that the power generation efficiency is improved.

  Here, a structure in which the number of stacking stages of the flat plate unit that is the reforming unit is smaller than the number of stacking stages of the solid oxide fuel cell unit that is the power generation unit, A narrow structure or a structure in which the pressure loss between flat plate units on which heat exchange fins and honeycomb materials are installed is higher than the pressure loss between solid oxide fuel cell units on which current collectors are installed can be adopted as appropriate. .

  The separator plate used in the flat plate unit, which is a reforming unit, is the same as the separator plate of the solid oxide fuel cell unit in order to improve the heat exchange efficiency and to form a fuel gas passage carrying a catalyst. It is desirable to form by pressing.

  When a steam reforming reaction is used as a reforming reaction in a fuel cell, since it is an endothermic reaction, the power generation output per supplied fuel molecule is high, and the power generation efficiency of the stack structure can be increased. There is. However, because it is necessary to supply heat to the reformer, the operating temperature of the reformer is higher than the operating temperature of the solid oxide fuel cell, and a system that generates combustion heat using fuel separately from the fuel cell However, the efficiency of the entire system may not be improved in the case of load fluctuation operation or when the low load partial load operation time is long.

  Therefore, in the fuel cell of the present invention, an ethanol conversion catalyst containing platinum and at least one oxide of cerium, titanium, and niobium as a catalyst filled or supported in the reforming flow path of the reformer. By using ethanol as a fuel, reforming can be performed even when the temperature of the reformer is lower than the operating temperature of the solid oxide fuel cell.

  As a result, unused fuel in the exhaust stream can be recovered and circulated, or burned for another purpose and used effectively, improving system efficiency even when partial load operation time is long. In addition, as a heat source to be supplied to the reformer, it is possible to cover with the sensible heat of one of the exhaust flow of one gas and the exhaust flow of the other gas. Therefore, it is possible to reduce the startup time of the entire system.

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

  1 to 6 show an embodiment of a fuel cell according to the present invention. As shown in FIG. 1, this fuel cell 10 includes a plurality of solid oxide fuel cell units 1 via a current collector 15. A stack structure 11 formed by stacking a plurality of layers, a gas introduction part 12a and a gas discharge part 12b, and air is introduced from the gas introduction part 12a and flows to the gas discharge part 12b in a state where the stack structure 11 is accommodated. A case 12 having a cylindrical shape and a reformer 40 for reforming fuel gas are provided.

  The solid oxide fuel cell unit 1 constituting the stack structure 11 of the fuel cell 10 includes a metal cell plate 2 having a circular thin plate shape and having a gas introduction hole 21 and a gas discharge hole 22 in the center, Similar to the cell plate 2, a metal separator plate 3 having a circular thin plate shape and having a gas introduction hole 31 and a gas discharge hole 32 at the center is provided. The cell plate 2 and the separator plate 3 are joined to each other with their outer peripheral edges facing each other, and the bag portion (space) S formed between the cell plate 2 and the separator plate 3 has a collection. The electric body 4 is accommodated.

  As shown in FIGS. 4 and 5, the central portions of the cell plate 2 and the separator plate 3 joined in a state of being opposed to each other are concentric with the outer peripheral edge and protrude in directions away from each other. The circular convex step portions 23 and 33 functioning as spacers are formed by pressing, and the outer peripheral edge portions of the cell plate 2 and the separator plate 3 are concentric with the outer peripheral edge portion. Further, annular steps 24 and 34 for projecting in a direction approaching each other to form a space S are formed by pressing, and the gas introduction holes 21 and 31 and the gas discharge holes 22 and 32 described above are formed on the cell plate 2. And the circular convex steps 23 and 33 of the separator plate 3.

  Further, as shown in FIG. 6, a single cell 6 having a donut shape is disposed between the circular convex stepped portion 23 and the annular stepped portion 24 of the cell plate 2. The outer peripheral edge 23 a of the stepped portion 23 and the inner peripheral edge 24 a of the annular step 24 are fixed. The single cell 6 may be any one of an electrolyte support cell, an electrode support cell, and a porous support cell.

  Further, of the circular convex stepped portions 23 and 33 located at the center portions of the cell plate 2 and the separator plate 3, the gas convexity step 33 of the separator plate 3 has a gas introduction flow communicating with the gas introduction hole 31. A flow path component 5 for supplying fuel gas into the space S formed between the cell plate 2 and the separator plate 3 with the passage 51 is accommodated, and the circular convex step portion 23 of the cell plate 2 is accommodated. Includes a gas discharge passage 52 communicating with the gas discharge hole 22 and contains a flow passage component 5 for discharging fuel gas from the space S. These flow passage components 5 and 5 will be described later. Thus, in the state where the stack structure 11 is formed by stacking the solid oxide fuel cell units 1, the stack structure 11 is in close contact with each other only by the pressing force.

  Furthermore, the reformer 40 has a rectangular parallelepiped shape as a whole, and includes a plurality of tubular reforming channels 41 carrying a reforming catalyst, and these reforming channels 41 are connected to a solid oxide fuel cell unit. 1, a manifold portion 42 having a state along the stacking direction 1 is provided, and an air passage 43 is formed between the reforming passages 41 of the manifold portion 42 through which the fuel gas passes. As shown in FIG. 2, the reformer 40 is disposed in the gas discharge part 12 b of the case 12, so that the air passing between the plurality of solid oxide fuel cell units 1 of the stack structure 11. Heat exchange between the exhaust gas flow and the fuel gas passing through the reforming flow path 41 of the reformer 40.

  In this example, the cell plate 2 and the separator plate 3 were SUS430 rolled plates having a thickness of 0.1 mm. Then, this rolled plate was set in a press machine equipped with a die made of cemented carbide and SKD11 and subjected to press working with a press load of 80 tons. The outer diameters of the cell plate 2 and the separator plate 3 obtained by this press working are 125 mm, and the outer peripheral edges of the cell plate 2 and the separator plate 3 are joined to each other by laser welding to obtain a thickness of 1.5 mm. The solid oxide fuel cell unit 1 was obtained. Further, the current collector 4 accommodated in the space S between the cell plate 2 and the separator plate 3 is made of Inconel metal mesh, and the periphery of the cell plate 2 and the separator plate 3 is laser welded. Joined.

  On the other hand, SUS430 is also used for the flow path component 5, and the cell plate 2 and the separator plate 3 are fixed by diffusion bonding in a vacuum at a bonding temperature of 1000 ° C. or less to prevent deformation at the time of bonding. . In addition, instead of diffusion bonding, bonding by laser welding using a YAG laser is also possible. At this time, since the cell plate 2 and the separator plate 3 are in a thin plate shape, even if laser is irradiated from the front side Can be joined. The flow path pattern of the flow path component 5 can be formed by etching, grinding, or laser processing, and can also be formed by stacking and joining etched components.

  In the fuel cell 10 according to this embodiment, the stack structure 11 is formed by stacking 40 layers of the solid oxide fuel cell unit 1 at intervals of 1.5 mm (not shown in FIG. 1 in four stages). As shown in FIG. 4, a plurality of stacked solid oxide fuel cell units 1 are sandwiched from above and below by flanges 13 and 14, and around each gas introduction hole 21 and 31 of the cell plate 2 and the separator plate 3. A plurality of stud bolts (not shown) are inserted through the formed gas discharge holes 22 and 32, respectively, and one end of the stud bolt is screwed into the upper flange 13 provided with the fuel gas introduction pipe 13a. The other end of the stud bolt projecting outside from the lower flange 14 provided with the exhaust pipe 14a is screwed onto the other end of the stud bolt via a disc spring so that they are laminated together. So that to fasten the fuel cell units 1 to each other.

  At this time, a ceramic adhesive 17 as a seal bonding material is applied in a double ring shape between the central portions of the solid oxide fuel cell units 1 that overlap each other. In addition, a glass-based adhesive or a gasket formed by adding ceramic fiber or filler to glass can be used as the seal bonding material, and when the single cell 6 forms a donut shape as in this embodiment Can use a paste-like adhesive mixed with metal powder, a gasket-like brazing material, or a metal gasket.

  In the fuel cell 10, the stack structure 11 is accommodated in the main body portion of the cylindrical case 12 made of SUS430, and the reformer 40 is accommodated in the gas discharge portion 12 b of the case 12. At this time, the flow path of the air flow path 43 of the reformer 40 through which the exhaust flow of air passes is larger than the total cross-sectional area between the plurality of solid oxide fuel cell units 1 of the stack structure 11 through which air passes. By reducing the total cross-sectional area, the pressure loss in the reformer 40 is increased.

  In this fuel cell 10, as shown in FIGS. 1 to 3, the fuel gas F that has passed through the reforming passage 41 carrying the reforming catalyst of the reformer 40 is introduced into the introduction pipe 13 a of the flange 13 and the solid electrolyte type. After being introduced into each space S formed between the cell plate 2 and the separator plate 3 through the gas introduction holes 21 and 31 of the fuel cell unit 1 and flowing through the space S, the gas discharge holes 22 and 32 and The exhaust is exhausted through the exhaust pipe 14 a of the flange 14.

  On the other hand, when the air Ai is introduced into the case 12 from the gas introduction part 12a, the current collector 15 located between the stacked solid oxide fuel cell units 1 of the stack structure 11, that is, between the layers on the cathode side. Pass through. The exhaust flow of the air Ai flowing between the solid oxide fuel cell units 1 and having a high temperature passes through the air flow path 43 of the reformer 40, thereby passing through the reforming flow path 41 of the reformer 40. After supplying heat to the flowing fuel gas, it is exhausted through the gas discharge part 12b.

  As described above, in the fuel cell 10, the exhaust flow of the air Ai that exchanges heat with the fuel gas F that passes through the reforming channel 41 of the reformer 40 does not mix with each other. The unused portion in the exhaust flow of the fuel gas F exhausted through the exhaust pipe 14a of the flange 14 with respect to the fuel gas F before reforming or the fuel gas F after reforming introduced into the reformer 40 Can be mixed and introduced into the stack structure 11 again.

  That is, the exhaust flow of the fuel gas F containing unused fuel is effectively utilized according to the operating state, for example, used for starting a fuel cell in the subsequent stage, generating electricity, or introducing it into an exhaust gas purification burner. Therefore, the controllability with respect to the fluctuation of the load becomes good, and the operation can be performed without reducing the fuel utilization rate.

  In the fuel cell 10 described above, the stacking direction of the plurality of solid oxide fuel cell units 1 of the stack structure 11 and the direction of the reforming flow path 41 of the reformer 40 are made parallel to each other, thereby improving the fuel cell 10. Since the compact arrangement of the mass device 40 and the stack structure 11 is realized, the sensible heat of the exhaust flow can be used for reforming without loss, and the efficiency can be improved.

  In addition, in the fuel cell 10 described above, the reformer 40 through which the exhaust flow of the air Ai passes is larger than the total cross-sectional area between the plurality of solid oxide fuel cell units 1 of the stack structure 11 through which the air Ai passes. By reducing the total cross-sectional area of the air flow path 43, the pressure loss in the reformer 40 is increased, so that the gas is interposed between the solid oxide fuel cell units 1 in which the single cells 6 are disposed. The flow velocity distribution and the gas flow distribution are uniform, and the air Ai reaches every corner. As a result, high power generation efficiency can be maintained.

  In the solid oxide fuel cell 1 of the stack structure 11 in the fuel cell 10 of the above-described embodiment, the cell plate 2 and the separator plate 3 have substantially the same shape, but are not limited thereto. For example, as shown in FIG. 7, the cell plate 2 to which the single cell 6 is attached has a shape having only the circular convex stepped portion 23, and the separator plate 3 has an annular stepped portion 34 that is about twice as high as a normal one. The shape may be formed.

  Further, in this embodiment, the case where the single cell 6 has a donut shape is shown. However, the present invention is not limited to this. For example, as shown in FIG. In addition, a plurality of single cells 6A having a circular shape can be attached to a region having a donut shape between the center portion and the outer peripheral edge portion of the cell plate 2, as shown in FIG. The fan-shaped single cell 6B is fixed to a frame formed by connecting the press-processed inner ring 7 and outer ring 8 joined to the circular convex stepped portion 23 and the annular stepped portion 24 of the cell plate 2 by a radial member 9, respectively. It is also possible.

  Further, in this embodiment, the reformer 40 has a manifold holder portion 42 having a rectangular parallelepiped shape, and the reforming channel 41 carrying the reforming catalyst is along the stacking direction of the solid oxide fuel cell unit 1. As shown in FIG. 9, for example, as shown in FIG. 9, the reformer 40A has a manifold holder portion 42A having a crescent-shaped cross section, and the inside of the manifold holder portion 42A is shown. In FIG. 10, the reforming channel 41A arranged along the outer peripheral edge of the stack structure 11 may have a tubular shape along the stacking direction of the solid oxide fuel cell unit 1. As shown in FIG. 4, the reformer 40B has a manifold holder portion 42B having a rectangular parallelepiped shape, and the reforming channel 41B carrying the reforming catalyst is a flat plate shape along the stacking direction of the solid oxide fuel cell unit 1. Made up of It may be the case.

  FIG. 11 shows another embodiment of the fuel cell of the present invention. As shown in FIG. 11, the fuel cell 110 includes a stack structure 11 formed by stacking a plurality of solid oxide fuel cell units 1 having the same configuration as the previous embodiment, a gas introduction part 112a, and a gas discharge part 112b. And a case 112 having a cylindrical shape that introduces air from the gas introduction part 112a and flows to the gas discharge part 112b in a state in which the stack structure 11 is accommodated, and a reformer 140 that reforms the fuel gas. .

  In this embodiment, the reformer 140 carries the reforming catalyst in the reforming channel 141 formed between the separator plates 3 and 3 used in the solid oxide fuel cell unit 1 by joining them together. A plurality of flat plate-type reforming units 101 are stacked, and an air flow path 143 is provided between adjacent flat plate-type reforming units 101 and 101. Then, the reforming channels 141 supporting the reforming catalyst of the flat plate-type reforming unit 101 are reformed so that the stacking directions of the plurality of solid oxide fuel cell units 1 of the stack structure 11 are orthogonal to each other. The container 140 and the stack structure 11 are accommodated in the case 112 in a stacked state.

  In this case, the case 112 is partitioned into a reformer housing portion 112A and a stack structure housing portion 112B, and the reformer 140 is disposed in the reformer housing portion 112A on the gas discharge portion 112b side of the case 112. Thus, heat exchange is performed between the exhaust flow Ai of air passing between the plurality of solid oxide fuel cell units 1 of the stack structure 11 and the fuel gas F passing through the reforming channel 141 of the reformer 140. I am trying to make it.

  When the reformer 140 is manufactured, a heat exchange fin 144 (a punching board having a thickness of 0.1 mm shown in FIG. 12 is waved between adjacent separator plates 3 and 3 of the flat plate-type reforming units 101 and 101 that overlap each other. In a state where fins bent into a plate shape are interposed, the circular convex stepped portions 33 and 33 of the separator plates 3 and 3 are joined to each other by nickel brazing and on the outer side surfaces of the separator plates 3 and 3. After joining the heat exchange fins 144 by nickel brazing, the catalyst carriers in the form of granules or pellets carrying the reforming catalyst are sequentially stacked while being packed in the reforming channels 141 and 141, respectively. As a final step, Each annular step 34, 34 is joined by laser welding to perform bag binding.

  At this time, the surface of the separator plate 3 on the side of each reforming channel 141 is coated with an oxide film such as alumina, magnesium oxide, zirconia, or the like, thereby preventing carbon deposition. In addition, since the plate-type reforming units 101 and 101 that overlap each other do not need to be electrically insulated, they are joined with a conductive joining material or with a joining material used between the solid oxide fuel cell units 1. You can do it.

  The reformer 140 is formed by stacking 20 layers of flat plate-type reforming units 101 at intervals of 1.5 mm (illustrated in three stages in FIG. 11), as shown in FIG. A plurality of flat plate reforming units 101 and a plurality of solid oxide fuel cell units 1 stacked on top of each other are sandwiched by flanges 13 and 14 from above and below, and formed around the gas introduction holes 21 and 31 of the cell plate 2 and the separator plate 3. A plurality of stud bolts (not shown) are respectively inserted into the plurality of gas discharge holes 22 and 32, and one end of the stud bolt is screwed into the upper flange 13 provided with the fuel gas introduction pipe 13a. Flat plates stacked on each other by screwing nuts through a disc spring to the other end of the stud bolt that protrudes outward from the lower flange 14 provided with the pipe 14a. So that to fasten the reforming unit 101 and the fuel cell units 1 to each other.

  In the fuel cell 110, the stack structure 11 is accommodated in the stack structure accommodating portion 112B of the case 112 made of SUS430 and has a reformer accommodating portion 112A on the gas discharge portion 112b side of the case 112. In this case, the reformer 140 is accommodated, and at this time, the exhaust flow of the air Ai is larger than the total cross-sectional area between the plurality of solid oxide fuel cell units 1 of the stack structure 11 through which the air Ai passes. By reducing the total cross-sectional area of the air flow path 143 of the reformer 140 through which the gas passes, the pressure loss in the reformer 140 is increased.

  In this fuel cell 110, as shown in FIGS. 11 and 13, each reforming channel 141 carrying the reforming catalysts of the plurality of plate-type reforming units 101 in the reformer 140 passes through the introduction pipe 13 a of the flange 13. The introduced fuel gas F is reformed and then in the spaces S formed between the cell plate 2 and the separator plate 3 through the gas introduction holes 21 and 31 of the solid oxide fuel cell unit 1 of the stack structure 11. Then, after flowing through the space S, the gas is exhausted through the gas exhaust holes 22 and 32 and the exhaust pipe 14 a of the flange 14.

  On the other hand, when the air Ai is introduced into the case 112 from the gas introduction part 112a, the current collector 15 located between the stacked solid oxide fuel cell units 1 of the stack structure 11, that is, between the layers on the cathode side. Pass through. The exhaust flow of the air Ai flowing between the solid oxide fuel cell units 1 and having a high temperature flows from the stack structure housing portion 112B to the reformer housing portion 112A on the gas discharge portion 112b side, and the reformer After passing through the air flow paths 143 between the plurality of flat plate reforming units 101 in 140, heat is supplied to the fuel gas F flowing through the reforming flow paths 141 of the reformer 140, and then exhausted through the gas discharge section 112b. Is done.

  As described above, also in the fuel cell 110 in this embodiment, the exhaust flow of the air Ai that exchanges heat with the fuel gas F that passes through the reforming channel 141 of the reformer 140 does not mix with each other. In the exhaust flow of the fuel gas F exhausted through the exhaust pipe 14a of the flange 14 with respect to the fuel gas F before reforming or the fuel gas F after reforming newly introduced into the reformer 140 The unused portion can be mixed and introduced into the stack structure 11 again.

  That is, the exhaust flow of the fuel gas F containing unused fuel is effectively utilized according to the operating state, for example, used for starting a fuel cell in the subsequent stage, generating electricity, or introducing it into an exhaust gas purification burner. Therefore, the controllability with respect to the fluctuation of the load becomes good, and the operation can be performed without reducing the fuel utilization rate.

  In the fuel cell 110 described above, the stacking direction of the plurality of solid oxide fuel cell units 1 of the stack structure 11 and the direction of the reforming flow channel 141 of the reformer 140 are orthogonal to each other. As a result, it is possible to freely design the number of stacking stages according to various conditions such as fuel composition, required reforming degree and power generation output. By controlling the installation pattern of the reforming gas flow path of the reformer that is a catalyst reaction tube, the gas flow between the solid oxide fuel cell units 1 can be made uniform, so that the power generation efficiency is improved. It will be.

  FIG. 14 shows still another embodiment of the fuel cell of the present invention. As schematically shown in FIG. 14, this fuel cell 210 includes a stack structure 211 and a reformer 240, and serves as an exhaust flow for exchanging heat with the reformed fuel gas Fa. The exhaust flow of the fuel gas Fb exhausted from the body 211 is used, and in this case, a dew condensation water recovery function can be installed at a portion to which the heat of the reformer 240 is supplied. As a result, water generated from the exhaust flow of the fuel gas accompanying power generation can be recovered with a compact structure.

It is plane explanatory drawing (a) which shows one Example of the fuel cell of this invention, and (a) Cross-sectional explanatory drawing (b) based on the AA line position. (Example 1) It is a simple perspective explanatory view explaining the flow of fuel gas and air of the fuel cell in FIG. (Example 1) FIG. 2 is an overall perspective view of the stack structure of the fuel cell in FIG. 1. (Example 1) FIG. 2 is an exploded perspective view of a solid oxide fuel cell unit constituting the fuel cell stack structure in FIG. 1. (Example 1) FIG. 5 is a partial vertical cross-sectional explanatory view of the solid oxide fuel cell unit of FIG. 4. (Example 1) FIG. 5 is an explanatory plan view of a cell plate showing an arrangement pattern of single cells in the solid oxide fuel cell unit of FIG. 4. (Example 1) FIG. 3 is a partial longitudinal cross-sectional explanatory view showing another configuration example of the solid oxide fuel cell unit constituting the stack structure of the fuel cell in FIG. 1. FIG. 4 is a plane explanatory view (a) and (b) of a cell plate showing another arrangement pattern of single cells of a solid oxide fuel cell unit constituting the stack structure of the fuel cell in FIG. 1. FIG. 3 is an explanatory plan view showing another configuration example of the reformer of the fuel cell in FIG. 1. FIG. 10 is an explanatory plan view (a) and a sectional explanatory view (b) based on the position of the BB line in FIG. It is a cross-sectional explanatory drawing which shows the other Example of the fuel cell of this invention. (Example 2) It is whole perspective view explanatory drawing of the heat exchange fin used for the fuel cell in FIG. It is a simple perspective explanatory view explaining the flow of fuel gas and air of the fuel cell in FIG. (Example 2) FIG. 6 is a simplified perspective view illustrating the flow of fuel gas and air of a fuel cell according to still another embodiment of the present invention. (Example 3)

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Solid oxide type fuel cell unit 2 Cell plate 3 Separator plate 6 Single cell 10 Fuel cell 11 Stack structure 12, 112 Case 12a, 112a Gas introduction part 12b, 112b Gas discharge part 40,140,240 Reformer 41,141 Reforming channel

Claims (7)

A reformer having a reforming channel filled or supported with a catalyst for reforming fuel gas;
A cell plate holding a single cell and having an introduction hole and a discharge hole for one of the fuel gas and air reformed by the reformer, and the fuel gas and air reformed by the reformer A plurality of solid oxide fuel cell units each having a separator plate having an introduction hole and a discharge hole for one of the gas plates and having an outer edge joined to an outer edge of the cell plate. A stack structure that introduces one gas and exhausts it from the discharge hole through each solid oxide fuel cell unit;
A solid electrolyte type comprising a gas introduction part and a gas discharge part and introducing the other gas of the fuel gas and air reformed by the reformer from the gas introduction part while containing the stack structure and overlapping each other It has a case that flows to the gas discharge part through between the fuel cell units,
Either of the exhaust flow of one gas passing through the plurality of solid oxide fuel cell units of the stack structure and the exhaust flow of the other gas passing between the plurality of solid oxide fuel cell units of the stack structure A fuel cell, wherein a reformer is positioned in the exhaust flow, and heat exchange is performed between the exhaust flow and a fuel gas passing through a reforming passage of the reformer. The fuel cell according to claim 1, wherein the exhaust flow for exchanging heat with the fuel gas passing through the reforming passage of the reformer is an air exhaust flow. The fuel cell according to claim 1, wherein the exhaust flow for exchanging heat with the fuel gas passing through the reforming flow path of the reformer is an exhaust flow of the fuel gas. The pressure loss when one of the exhaust stream of one gas and the exhaust stream of the other gas passes through the reformer causes the other solid oxide fuel cell unit of the stack structure to pass between the other. The fuel cell according to any one of claims 1 to 3, wherein the fuel cell has a pressure loss that is greater than a pressure loss at a stage where gas passes. The stacking direction of the plurality of solid oxide fuel cell units of the stack structure and the direction of the reforming flow path of the reformer are parallel to each other. Fuel cell. The fuel cell according to any one of claims 1 to 4, wherein the stacking direction of the plurality of solid oxide fuel cell units of the stack structure and the direction of the reforming flow path of the reformer are orthogonal to each other. . The ethanol conversion catalyst containing platinum and at least one oxide of cerium, titanium, and niobium is used as a catalyst that is filled or supported in the reforming flow path of the reformer. The fuel cell according to any one of the items.

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