JP2016177883A - Air preheater and power generator - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide an air preheater capable of preheating the air introduced to a fuel cell stack efficiently, while reducing heat dissipation to the outside, and to provide a power generator including a fuel cell module having the air preheater.SOLUTION: An air preheater 24 is provided in a fuel cell module 10 surrounded by a heat insulation housing 16, and preheats the air supplied to a fuel cell stack 14. The air preheater 24 includes a first preheating part 50a provided with an air passage 66 for circulating the air introduced externally, and a second preheating part 50b provided via a partition wall 56 with respect to the first preheating part 50a, and provided with an air passage 72 for circulating the air passed through the first preheating part 50a, between the partition wall 56 and an outer wall 78 arranged oppositely to the fuel cell stack 14.SELECTED DRAWING: Figure 6

Description

  The present invention relates to an air preheater for preheating air introduced into a fuel cell stack, and a power generation apparatus including a fuel cell module having the air preheater.

  A high-temperature fuel cell such as a solid oxide fuel cell has an operating temperature of about 600 ° C. to 1000 ° C., and is used as a reformed gas mainly composed of hydrogen introduced into the fuel electrode (anode) or an air electrode (cathode). When air containing oxygen or the like to be introduced is introduced into the fuel cell stack at room temperature, a large temperature difference generates a large thermal stress in the constituent material (ceramics), which causes deterioration or breakage (cell cracking) of the material.

  When reforming a hydrocarbon-based fuel such as natural gas or LPG and introducing it into the anode, the reaction temperature of the reformer is about 600 ° C. to 750 ° C., which is close to the operating temperature of the fuel cell. Then, the generation of thermal stress due to the temperature difference between the fuel cell and the supply gas is small. On the other hand, when air is introduced into the cathode, it must be preheated before thermal stress is generated due to the temperature difference between the fuel cell and air, which may cause deterioration and damage to the fuel cell. The air preheater which preheats is used.

  For example, Patent Document 1 discloses an air preheater that uses combustion gas from a combustion chamber that burns fuel exhaust gas and preheats air introduced into the fuel cell stack in a power generation system using a solid oxide fuel cell. In addition, a configuration in which a preheating air temperature adjusting unit and a combustion gas temperature adjusting unit are installed is described.

  Patent Document 2 includes a bypass line that bypasses the air preheater and supplies the fuel cell stack without preheating air, and an arithmetic unit that performs arithmetic processing on the air flow rate information of each line of the supplied air. A fuel cell operation control system is also described.

  Patent Document 3 includes a combustor that burns fuel exhaust gas discharged from a fuel cell stack, and an air preheater that preheats air using combustion gas from the combustor, and an air preheater around the fuel cell stack. The installed configuration is described.

JP 2009-224041 A JP 2001-202981 A JP 2012-198994 A

  Since solid oxide fuel cells use ceramics as the cell material, there is the problem of cracking due to thermal stress due to temperature differences as described above. It is necessary to design so that it does not stick.

  For this reason, both the fuel and air introduced into the fuel cell need to be close to the fuel cell operating temperature. In particular, air as the cathode gas has a problem of raising the temperature from room temperature to about the operating temperature of the fuel cell. Further, when the fuel exhaust gas from the fuel cell stack is burned using the air exhaust gas, the amount of air supplied to the cathode is not only the amount necessary for the fuel cell reaction but also the amount of combustion. As a result, the amount of preheating before introduction into the fuel cell stack is further increased, and thus an air preheater capable of ensuring sufficient heat exchange efficiency and heat exchange amount is required.

  On the other hand, in the high-temperature fuel cell as described above, the fuel cell stack may be configured as a high-temperature fuel cell module housed in a heat insulating housing together with an air preheater, a reformer, or the like. In this case, if the heat radiation from the fuel cell module is large, the inside of the module cannot be thermally independent. If it does so, it will be necessary to increase the combustion amount of fuel exhaust gas, the fuel utilization rate in a fuel cell will fall, and the power generation efficiency of the whole apparatus will fall.

  The present invention has been made in consideration of the above-described conventional problems, and can efficiently preheat the air introduced into the fuel cell stack, and reduce the heat dissipation to the outside, and the air preheater It aims at providing the electric power generating apparatus provided with the fuel cell module which has an air preheater.

  An air preheater according to the present invention is an air preheater that is provided in a fuel cell module surrounded by a heat insulating casing and preheats air supplied to a fuel cell stack, and is introduced from the outside of the heat insulating casing. A first preheating unit that preheats by circulating air and a second preheating unit through which air after passing through the first preheating unit flows are provided.

  According to such a configuration, since the air can be preheated by the first preheating unit and the second preheating unit, the air before being introduced into the fuel cell stack can be efficiently preheated, and the amount of preheating is increased. But it can respond enough. In addition, since the radiant heat and reaction heat from the fuel cell stack can be received by the air preheater, heat radiation from the heat insulating housing to the outside can be reduced.

  The second preheating part may be arranged on the fuel cell stack side rather than the first preheating part. As described above, when the first preheating unit that preheats the air from the outside first is disposed on the back side of the second preheating unit disposed on the fuel cell stack side, the outer surface temperature of the air preheater is decreased, Radiation of the radiant heat and reaction heat to the back side can be reduced, and heat radiation from the heat insulating housing to the outside can be reduced.

  The first preheating unit causes air introduced from the outside of the heat insulating housing to flow through a first air flow path formed between a partition wall that partitions the second preheating unit and a first outer wall. Preheating is performed, and the second preheating unit causes the air flowing out from the first preheating unit to flow through a second air flow path formed between the partition wall and a second outer wall disposed to face the fuel cell stack. It may be further preheated and supplied to the fuel cell stack. As described above, when one surface of the second air flow path of the second preheating unit that heats air later is configured by the second outer wall disposed to face the fuel cell stack, the radiant heat from the fuel cell stack is generated by the second preheating unit. The air immediately before being introduced into the fuel cell stack can be preheated with a large amount of heat to a higher temperature.

  The first preheating unit and the second preheating unit effectively recover the radiant heat from the fuel cell stack when the air supplied to the fuel cell stack is preheated using the radiant heat from the fuel cell stack. The air can then be preheated.

  When heat transfer fins are provided in the first air flow path and the second air flow path, the heat exchange performance can be further improved.

  One end of the heat transfer fin of the first air flow path is fixed to the partition wall, and one end of the heat transfer fin of the second air flow path is fixed to the inner surface of the second outer wall. Is preferred. If it does so, since a heat-transfer fin is fixed to the 2nd wall surface and partition wall of a high temperature side, a radiant heat can be directly transmitted with respect to a heat-transfer fin.

  The main preheater having the first preheater and the second preheater, and the main preheater are provided separately from the main preheater, and further preheats the air flowing out from the first preheater to the second preheater. It is good also as a structure provided with the auxiliary | assistant preheater made to flow in.

  A plurality of auxiliary preheaters are provided, and a plurality of air outlets are provided in the first preheater and a plurality of air inlets are provided in the second preheater so as to correspond to the plurality of auxiliary preheaters, respectively. May be provided.

  The power generator according to the present invention includes a fuel cell stack, an air preheater that preheats air supplied to the fuel cell stack, and a heat insulating casing that surrounds the fuel cell stack and the air preheater. A power generation device including a module, wherein the air preheater preheats air introduced from the outside of the heat insulating casing through a first air flow path formed between a partition wall and a first outer wall. A first preheating portion that is formed and air that has flowed out of the first preheating portion is formed between the partition wall that partitions the first preheating portion and a second outer wall that is disposed to face the fuel cell stack. And a second preheating portion that is further preheated by being passed through the two air flow paths and is supplied to the fuel cell stack.

  According to such a configuration, since air can be preheated by the two layers of the first preheating part and the second preheating part partitioned by the partition wall, the air before being introduced into the fuel cell stack is efficiently preheated. Therefore, even if the amount of preheating increases, it can sufficiently cope. In addition, since one surface of the second air flow path of the second preheating unit that heats the air later is constituted by the second outer wall disposed to face the fuel cell stack, the radiant heat from the fuel cell stack is generated by the second preheating unit. The air immediately before being introduced into the fuel cell stack can be preheated to a higher temperature with a large amount of heat. Further, since the first preheating part that heats the air from the outside first is arranged on the back side of the second preheating part arranged on the fuel cell stack side, the outer surface temperature of the air preheater is lowered, The radiation of the radiant heat to the back side can be reduced, and the radiation from the heat insulating casing to the outside can be reduced.

  The main preheater having the first preheater and the second preheater, and the main preheater are provided separately from the main preheater, and further preheats the air flowing out from the first preheater to the second preheater. A plurality of auxiliary preheaters to be introduced, the first preheating section includes a plurality of air outlets, and the second preheating section includes a plurality of air so as to respectively correspond to the plurality of auxiliary preheaters. It is good also as a structure in which an inflow port is provided.

  Two auxiliary preheaters are provided, the air outlets are provided on both side surfaces of the first preheating unit, the air inlets are provided on both side surfaces of the second preheating unit, and the two The auxiliary preheaters may be configured to be installed on opposing surfaces of the fuel cell stack.

  The fuel cell stack may be a solid oxide fuel cell. By providing an air preheater together with the fuel cell stack of this solid oxide fuel cell, the temperature of the air introduced into the air electrode can be efficiently preheated to a desired temperature. Generation of cell cracks due to the generation can be suppressed as much as possible.

  The solid oxide fuel cell may have a rectangular parallelepiped shape in which rectangular flat plates are stacked.

  The solid oxide fuel cell may have a structure in which a plurality of stages are arranged vertically and a plurality of solid oxide fuel cells are installed in each stage.

  The fuel cell module further includes a reformer that reforms the fuel introduced into the fuel cell stack and a vaporizer that generates water vapor introduced into the reformer inside the heat insulating casing. The reformer may be installed on the side facing the main preheater with the fuel cell stack interposed therebetween, and the vaporizer may be installed above the fuel cell stack.

  According to the present invention, since the air can be preheated by the first preheating part and the second preheating part, the air before being introduced into the fuel cell stack can be efficiently preheated. Moreover, since the radiant heat can be received from the fuel cell stack by the air preheater, the heat radiation from the heat insulating casing to the outside can be reduced.

FIG. 1 is a block diagram illustrating a configuration of a power generation device including a fuel cell module according to an embodiment of the present invention. FIG. 2 is a perspective view illustrating a configuration example of a fuel cell module including an air preheater according to an embodiment of the present invention. FIG. 3 is a plan view showing a schematic configuration of the fuel cell module shown in FIG. FIG. 4 is a plan view of the shelf device. FIG. 5 is a configuration diagram of an air preheater according to an embodiment of the present invention, FIG. 5 (A) is a plan view, FIG. 5 (B) is a front view, and FIG. These are sectional drawings which follow the VC-VC line in FIG.5 (B). FIG. 6 is a perspective view showing the internal structure of the air preheater as seen from the front side. FIG. 7 is a perspective view showing the internal structure of the main preheater viewed from the back side. 8 is a configuration diagram of the main preheater, FIG. 8A is a cross-sectional view taken along line VIIIA-VIIIA in FIG. 8B, and FIG. 8B is a front view of the main preheater. FIG. 8C is a cross-sectional view taken along line VIIIC-VIIIC in FIG. 8B. 9 is a configuration diagram of the main preheater as viewed from the side, FIG. 9A is a side view, and FIG. 9B is taken along line IXB-IXB in FIG. 8B. It is sectional drawing and FIG.9 (C) is a side view of the partition which partitions off the inside of a main preheater. FIG. 10 is a plan view showing a configuration example of a support base for supporting the air preheater in the heat insulating casing. FIG. 11 is a plan view showing a configuration example in which an air preheater is arranged in a fuel cell stack according to a modification.

  DESCRIPTION OF EMBODIMENTS Hereinafter, an air preheater according to the present invention will be described in detail with reference to the accompanying drawings by giving preferred embodiments in relation to a fuel cell module equipped with the air preheater and a power generation device.

  First, the overall configuration of the power generation device 12 including the fuel cell module 10 will be described with reference to FIG. FIG. 1 is a block diagram illustrating a configuration of a power generation device 12 including a fuel cell module 10 according to an embodiment of the present invention.

  As shown in FIG. 1, the power generator 12 includes a fuel cell module 10 in which a fuel cell stack 14 is provided inside a heat insulating housing 16, fuel supply lines LF <b> 1 and LF <b> 2 that supply fuel and air to the fuel cell module 10, and Air supply lines LA1 and LA2, a hot water heat exchanger 18 that produces hot water using exhaust heat from the fuel cell module 10, and water for generating steam for reforming used in the fuel cell module 10 It is comprised as a cogeneration system provided with the condensed water tank 20 to store.

  The fuel cell module 10 includes a fuel cell stack 14, a reformer 22, an air preheater 24, and a vaporizer 26. The fuel cell module 10 includes an inside of a heat insulating casing 16 that defines a heat insulating member in a box shape (high temperature). Room). A general heat insulating material such as glass wool may be used as the heat insulating member. However, the fuel cell module 10 can be configured more compactly by using a board-shaped high-performance heat insulating material.

  The fuel cell stack 14 has a known configuration in which a plurality of rectangular flat power generation cells that generate power by reacting fuel introduced from the fuel supply line LF2 and air introduced from the air supply line LA2 are stacked. In the case of the present embodiment, the fuel cell stack 14 is constituted by a solid oxide fuel cell (SOFC) in which ion conductive ceramics are interposed as an electrolyte between a fuel electrode (anode) 14a and an air electrode (cathode) 14b. doing. When the solid oxide fuel cell is configured by a flat stack stack, the fuel cell stack 14 can be configured compactly, and the power generation output per volume can be increased. Other high-temperature fuel cells such as a molten carbonate fuel cell (MCFC) may be used as the fuel cell stack 14. On the side of the fuel cell stack 14, a heater 28 for raising the temperature is installed.

  The raw fuel (for example, methane gas, city gas, etc.) from the fuel supply line LF1 becomes a reformed fuel containing hydrogen and carbon monoxide via the desulfurizer 30 and the reformer 22, and is transferred from the fuel supply line LF2 to the fuel electrode 14a. And introduced. The reformer 22 may have a known configuration, and various reforming catalysts are provided therein. The vaporizer 26 evaporates the water sent from the flocculated water tank 20 that stores the flocculated water from the hot water heat exchanger 18 to generate reforming steam, and the generated steam is modified from the steam supply line LW. It is introduced into the fuel supply line LF1 immediately before being introduced into the mass device 22. As a result, the fuel is mixed with the steam heated to a high temperature in the vaporizer 26 and heated to, for example, about 300 ° C. and then introduced into the reformer 22 where the temperature is increased to about 700 ° C. while steam reforming. It becomes a reformed fuel.

  Air from the air supply line LA1 is introduced into the air preheater 24 by the blower 32, preheated to a desired temperature (for example, about 650 to 700 ° C.), and then introduced from the air supply line LA2 to the air electrode 14b. The

  The exhaust gas from the fuel cell stack 14 is sent to the hot water heat exchanger 18 from the exhaust gas line LG. The hot water heat exchanger 18 produces hot water by heating the water supplied from the water storage tank 36 with the exhaust gas from the exhaust gas line LG, and the produced hot water is returned to the water storage tank 36. In the water storage tank 36, makeup water is supplied and warm water is taken out. Further, the exhaust gas that has passed through the hot water heat exchanger 18 is condensed and removed by the condensed water tank 20 and exhausted. The condensed water is supplied to the vaporizer 26 as reforming water. The condensed water tank 20 is provided with a level meter, and makeup water is supplied when the water is below a certain level. Thereby, unnecessary gas and excess water are exhausted and drained.

  Next, a specific configuration example of the fuel cell module 10 constituting the power generation device 12 as described above will be described.

  2 is a perspective view showing a configuration example of the fuel cell module 10 including the air preheater 24 according to the embodiment of the present invention, and FIG. 3 is a schematic configuration of the fuel cell module 10 shown in FIG. FIG. In the following, for the fuel cell module 10 and the air preheater 24, the front side in FIG. 2 is called the front side (front side), the back side is called the rear side (back side), and the left-right direction is called the width direction (left-right width direction). I will explain it.

  As shown in FIG. 2, in this embodiment, a fuel cell module 10 having a set of four units in which four fuel cell stacks 14 are provided in one heat insulating casing 16 is used. In the fuel cell module 10, two fuel cell stacks 14 are placed on the upper shelf 40a and the lower shelf 40b of the shelf device 40 installed in the heat insulating casing 16, and arranged in two rows and two columns in front view. It has become. Hereinafter, such a set of four fuel cell stacks 14 may be collectively described as the fuel cell stack 14.

  FIG. 4 is a plan view of the shelf device 40 and shows a planar structure of the upper shelf 40a.

  As shown in FIG. 4, the upper shelf 40a has a bent portion 40c bent upward at the front and rear end portions (see also FIG. 2), and has a structure in which two fuel cell stacks 14 can be installed on the upper surface. The upper shelf 40a has left and right cutouts 40d penetrating in the plate thickness direction at locations where the fuel cell stack 14 is installed. Piping and wiring connected to the fuel cell stack 14 can be passed through the notch 40d. Although FIG. 4 illustrates the T-shaped cutout 40d, the cutout 40d may be a hole having a round shape or a rectangular shape.

  The lower shelf 40b has four columns 40e extending from the lower surface of the upper shelf 40a at the four corners, a plate 40f extending from the center in the width direction of the upper shelf 40a is provided at the center, and the bent portion 40c is not provided. The basic structure is the same as that of the upper shelf 40a. Accordingly, the notches 40d are also provided on the left and right sides of the lower shelf 40b, and two fuel cell stacks 14 can be installed on the upper surface thereof. The plate 40f functions as a heat shield that partitions the left and right fuel cell stacks 14, 14 installed on the lower shelf 40b. The plate 40f supports the upper shelf 40a.

  The shelf device 40 is for installing a set of four fuel cell stacks 14, but the same structure can be used when the number of installed fuel cell stacks 14 is increased. For example, the upper shelf 40a is stacked. You may comprise in three steps or more.

  In the fuel cell module 10, a flat box-shaped reformer 22 is installed along the vertical direction so as to face the front of the fuel cell stack 14 placed on the shelf device 40, and flattened above the fuel cell stack 14. A box-shaped carburetor 26 is installed, and an air preheater 24 is installed so as to surround the back surface of the fuel cell stack 14 and the left and right side surfaces.

  In the fuel cell module 10 in the heat insulating casing 16, the reformer 22 and the air preheater 24 that require high temperatures are arranged on the front and back of the fuel cell stack 14, and the vaporizer 26 that may be at a lower temperature than these. Is disposed above the fuel cell stack 14. The reformer 22 has a flat box shape as described above and is disposed so as to cover the front surface of each fuel cell stack 14. The air preheater 24 that requires a larger amount of heat than the reformer 22 is disposed so as to cover the back surface of each fuel cell stack 14 and further to cover the left and right side surfaces of the fuel cell stack 14 in a set of four. Yes.

  Then, next, the specific structural example of the air preheater 24 is demonstrated.

  FIG. 5 is a configuration diagram of the air preheater 24 according to the embodiment of the present invention, FIG. 5 (A) is a plan view, FIG. 5 (B) is a front view, and FIG. ) Is a cross-sectional view taken along line VC-VC in FIG. FIG. 6 is a perspective view showing the internal structure of the air preheater 24 as seen from the front side.

  As shown in FIGS. 5 and 6, the air preheater 24 includes a main preheater 50 disposed on the back side of the fuel cell stack 14 and a pair of auxiliary preheats disposed on the left and right side surfaces of the fuel cell stack 14. And a gate shape that covers three surfaces of the fuel cell stack 14 in plan view. The main preheater 50 and each auxiliary preheater 52 are connected by bridges 54 and 55 in the form of rectangular cylinders provided above and below, respectively, so that air can flow. The air preheater 24 is made of, for example, stainless steel.

  FIG. 7 is a perspective view showing the internal structure of the main preheater 50 as seen from the back side. 8 is a configuration diagram of the main preheater 50, FIG. 8A is a cross-sectional view taken along line VIIIA-VIIIA in FIG. 8B, and FIG. FIG. 8C is a cross-sectional view taken along line VIIIC-VIIIC in FIG. 8B. Moreover, FIG. 9 is the block diagram which looked at the main preheater 50 from the side surface side, FIG. 9 (A) is a side view, FIG. 9 (B) is IXB-IXB in FIG. 8 (B). FIG. 9C is a side view of the partition wall 56 that partitions the inside of the main preheater 50.

  As shown in FIGS. 6 to 9, the main preheater 50 is a flat box-shaped heat exchanger in which the inside is partitioned into two front and rear layers by a flat partition wall 56 along the vertical direction. The 1st preheating part 50a is provided in the back side of the partition 56, and the 2nd preheating part 50b is provided in the front side.

  As shown in FIG. 7 and FIG. 9B, the air introduced from the air supply line LA1 on the inlet side is diffused in the width direction at the upper part of the first preheating part 50a and the second preheating part 50b. A buffer space 58 is provided for evenly flowing into one preheating portion 50a in the width direction. In addition, the air heated in the second preheating unit 50b and diffused in the width direction is gathered at the lower part of the first preheating unit 50a and the second preheating unit 50b, and smoothly flows to the air supply line LA2 on the outlet side. A buffer space 60 is provided for introduction into the system.

  As shown in FIG. 9C, the upper and lower ends of the partition wall 56 are bent to one side (rear side). Thereby, it has the rigidity higher than the case where the flat plate which is not bent is used, and is arrange | positioned in the main preheater 50. FIG. The bent piece 56a bent in the horizontal direction at the top is a cover plate for partitioning the buffer space 58 from the first preheating portion 50a and the second preheating portion 50b together with the front strip 62. 9 (B)). A plurality of semicircular hole portions 56b arranged in the width direction are formed at the end edge portion of the bent piece 56a (see FIGS. 7 and 8A). The hole 56b is an opening serving as an air inlet from the buffer space 58 to the first preheating unit 50a. Further, the bent piece 56c bent in the horizontal direction at the lower portion is a cover plate that partitions the buffer space 60 from the first preheating portion 50a and the second preheating portion 50b together with the band plate 64 on the front side. (See FIG. 9B). A plurality of semicircular hole portions 64a arranged in the width direction are formed in the rear edge portion of the band plate 64 (see FIG. 8C). The hole 64 a is an opening that serves as an air outlet from the second preheating unit 50 b to the buffer space 60.

  As shown in FIG. 7, the first preheating unit 50a is a heat exchanger having an air flow channel 66 through which air introduced from the outside via the air supply line LA1 first flows. The first preheating part 50a is provided with holes 56b serving as inlets from the buffer space 58 at the upper part, and outlets (air outlets) 68 and 68 communicating with the left and right bridges 55 on the lower side walls, respectively. A plurality of heat transfer fins 70 are interposed in the air flow path 66. As a result, in the first preheating part 50a, the air that has flowed in from the holes 56b at the upper end flows downward while spreading in the width direction of the air flow channel 66, and the heat transfer fins 70, the partition walls 56, and the outer wall in the middle thereof After the temperature is raised by exchanging heat with 71 etc., it is introduced from the outlet 68 to the auxiliary preheater 52 through the bridge 55. Each heat transfer fin 70 is welded and fixed to the partition wall 56 on the high temperature side (front side) by a welded portion W (see FIG. 9B).

  As shown in FIG. 6, the second preheating unit 50 b is a heat exchanger having an air flow path 72 through which air heated by the first preheating unit 50 a and further heated by the auxiliary preheater 52 flows. The second preheating part 50b is provided with inlets (air outlets) 74, 74 communicating with the bridge 54 on both side walls of the upper part, and with holes 64a serving as outlets at the lower part (FIG. 8 ( C)), a plurality of heat transfer fins 76 are interposed in the middle of the air flow path 72. As a result, in the second preheating part 50b, the air flowing from the auxiliary preheater 52 via the bridges 54 from both upper side parts flows downward while spreading in the width direction of the air flow path 72, and in the middle of the heat transfer fins After the temperature is raised by exchanging heat with the outer wall 76 and the outer wall 78, etc., they are introduced from the holes 64a and the buffer spaces 60 into the fuel cell stacks 14 through the air supply lines LA2. Each heat transfer fin 76 is welded and fixed to the outer wall 78 on the high temperature side (front side) by a welded portion W (see FIG. 9B).

  As shown in FIGS. 5 and 6, the pair of auxiliary preheaters 52 and 52 are connected in parallel to the main preheater 50, and the first preheater 50 a and the first preheater 50 a constituting the main preheater 50 are connected to each other. It becomes an intermediate heat exchanger between two preheating parts 50b.

  Each auxiliary preheater 52 is a flat box-shaped heat exchanger having an air flow path 80 through which air heated by the first preheater 50a flows. The auxiliary preheater 52 is provided with an inlet (air inlet) 82 communicating with the bridge 55 on the lower back side of the inner wall 81, and an outlet (air outlet) 84 communicating with the bridge 54 on the upper front side of the inner wall 81. Is provided, and a plurality of heat transfer fins 86 are interposed in the middle of the air flow path 80. As a result, in the auxiliary preheater 52, the air flowing from the first preheater 50a of the main preheater 50 through the bridge 55 to the lower back side through the inlet 82 flows upward through the air flow path 80. The temperature is raised by exchanging heat with the heat transfer fins 86 and the inner walls 81 on the way, and then introduced from the outlet 84 to the second preheating part 50 b of the main preheater 50 through the bridge 54. Each heat transfer fin 86 is welded and fixed to the inner wall 81 on the high temperature side (fuel cell stack 14 side) by a welded portion W (see FIG. 6).

  Next, an air preheating method in the air preheater 24 configured as described above will be described.

  External air (for example, about 50 ° C.) supplied from the air supply line LA1 first passes through the hole 56a from the buffer space 58 of the main preheater 50 as shown in FIGS. 7 and 9B. It introduce | transduces into the outer 1st preheating part 50a.

  In the first preheating part 50a, the air flowing from the upper hole part 56a and flowing through the air flow channel 66 exchanges heat with the heat transfer fins 70, the partition walls 56, the outer wall 71 and the like, and is heated to about 150 ° C., for example. (See FIGS. 7 and 9B). In the first preheating part 50a, the radiant heat from the back surface of the fuel cell stack 14 operating at 700 to 800 ° C. is obtained by contact with the partition wall 56 on the fuel cell stack 14 side and the heat transfer fins 70 fixed to the partition wall 56 by welding. The air flowing through can be indirectly heated, and sufficient heat exchange can be performed.

  The air that has branched out from the first preheating part 50 a to the left and right bridges 55 flows into the air flow paths 80 from the inlets 82 at the lower part of the left and right auxiliary preheaters 52, 52. Then, heat is exchanged with the heat transfer fins 86 and the inner walls 81 and the like while circulating in the air flow path 80 of each auxiliary preheater 52 in parallel, and the temperature is raised to, for example, about 350 ° C. (see FIG. 6). Since the auxiliary preheater 52 faces the side surface of the fuel cell stack 14, it is possible to sufficiently heat the air flowing by the radiant heat from the side surface of the fuel cell stack 14. The heated air flows out to the second preheating part 50b of the main preheater 50 through the bridge 54 and merges again here.

  In the second preheating part 50b, the air flowing from the left and right upper inlets 74, 74 and flowing through the air flow path 72 exchanges heat with the heat transfer fins 76, the outer wall 78, etc., and rises to about 650-700 ° C., for example. (See FIG. 6). In the second preheating unit 50b, the air flowing by receiving the radiant heat from the back surface of the fuel cell stack 14 can be heated, and sufficient heat exchange can be performed. The heated air flows from the lower holes 64a to the buffer space 60 (see FIG. 8C and FIG. 9B), and the air in each fuel cell stack 14 via the air supply line LA2. It is introduced into the electrode 14b (see FIG. 1) and reacts with the reformed fuel in the fuel electrode 14a to generate electricity.

  In the case of this embodiment, the inner diameter and the pipe length of each pipe of the air supply line LA2 from the air outlet of the air preheater 24 to each fuel cell stack 14 are set to be the same. Thereby, the supply gas can be equally distributed from the air preheater 24 to each fuel cell stack 14, and the performance of each fuel cell stack 14 can be balanced. Even when the number of fuel cell stacks 14 is further increased, stable system efficiency can be obtained by the same countermeasure. Moreover, if a heat insulating material is installed between the air preheater 24 and each pipe, the heat reception of the pipe can be suppressed, and fluctuations in the air temperature supplied to each fuel cell stack 14 can be suppressed.

  The auxiliary preheater 52 connected between the first preheater 50a and the second preheater 50b constituting the main preheater 50 is provided for the fuel cell module 10 and the power generator 12 to which the air preheater 24 is applied. It may be omitted depending on the specifications. That is, when the amount of heat required for air preheating is sufficient with only the main preheater 50, it is also effective to omit the auxiliary preheater 52 and reduce the manufacturing cost of the air preheater 24. When the auxiliary preheater 52 is omitted, for example, the outlet 68 of the first preheater 50a of the main preheater 50 and the inlet 74 of the second preheater 50b are connected by a predetermined pipe, etc. What is necessary is just to set it as the structure which the air from the preheating part 50a distribute | circulates to the 2nd preheating part 50b.

  As described above, the air preheater 24 according to the present embodiment is provided in the fuel cell module 10 surrounded by the heat insulating casing 16 and preheats the air supplied to the fuel cell stack 14. The air preheater 24 includes a first preheating unit 50a that preheats the air introduced from the outside of the heat insulating housing 16 and a second preheating unit 50b through which air after passing through the first preheating unit 50a flows. With.

  Therefore, in such an air preheater 24, since the air can be heated by the first preheating unit 50a and the second preheating unit 50b, the air before being introduced into the fuel cell stack 14 can be efficiently preheated. Even if the amount of preheating increases, it can sufficiently cope. Moreover, since the radiant heat from the fuel cell stack 14 can be received by the air preheater 24, heat radiation from the heat insulating casing 16 to the outside can be reduced.

  In the air preheater 24, since the second preheater 50b is arranged closer to the fuel cell stack 14 than the first preheater 50a, the outer surface temperature of the air preheater 24 is lowered and the radiation heat is radiated to the back side thereof. And heat radiation from the heat insulating housing 16 to the outside can be further reduced.

  In the air preheater 24, the first preheating unit 50a is configured between the partition wall 56 and the outer wall (first outer wall) 71 that partition the air introduced from the outside of the heat insulating housing 16 with the second preheating unit 50b. The second preheating unit 50b is arranged to face the partition wall 56 and the fuel cell stack 14 so that the air flowing out from the first preheating unit 50a is preheated by flowing through the formed air channel (first air channel) 66. It is configured to flow through an air flow path (second air flow path) 72 formed between the outer wall (second outer wall) 78 and further preheat and supply to the fuel cell stack 14. Thereby, the radiant heat from the fuel cell stack 14 can be directly received by the second preheating unit 50b, and the air immediately before being introduced into the fuel cell stack can be preheated to a higher temperature with a large amount of heat.

  As described above, the air preheater 24 and the power generation apparatus 12 including the air preheater 24 include the first preheating part 50a and the second preheating part 50b provided in two layers via the partition wall 56, and are provided on the back surface of the fuel cell stack 14. An air flow path 72 of the second preheating portion 50b is provided between the outer wall 78 and the partition wall 56 that are arranged to face each other. Thereby, air can be preheated by the two layers of the first preheating part 50a and the second preheating part 50b partitioned by the partition wall 56, so that the air before being introduced into the fuel cell stack 14 can be efficiently preheated. it can. In addition, since one surface of the air flow path 72 of the second preheating unit 50b that preheats the air later is constituted by the outer wall 78 disposed to face the back surface of the fuel cell stack 14, it is immediately before being introduced into the fuel cell stack 14. Air can be preheated to a higher temperature with a greater amount of heat. Further, the first preheating part 50a that preheats the air from the outside first is arranged on the back side of the second preheating part 50b arranged on the fuel cell stack 14 side. That is, since the first preheating part 50a has a lower temperature than the second preheating part 50b, the outer surface temperature of the air preheater 24 is lowered, the heat radiation of the radiant heat to the back side is reduced, and the heat insulating casing 16 The heat radiation from the outside to the outside can be reduced.

  The power generator 12 (fuel cell module 10) according to the present embodiment includes the fuel cell module 10 having such an air preheater 24, a fuel cell stack 14, and a heat insulating casing 16 surrounding them. In the power generation device 12, since heat release from the heat insulating housing 16 to the outside can be reduced by the air preheater 24 as described above, it is possible to maintain heat self-supporting in the module.

  Here, in the case of the present embodiment, since a flat stack of solid oxide fuel cells is used as the fuel cell stack 14, a high power generation output can be obtained. There is a problem that thermal stress is likely to occur due to a temperature difference, and there is a high risk of the cell breaking. In this regard, since the power generation device 12 includes the air preheater 24 that can efficiently preheat air to a desired temperature as described above, the temperature of the air introduced into the air electrode 14b is introduced into the fuel electrode 14a. The temperature can be increased to a temperature equivalent to the reformed fuel (for example, about 650 to 700 ° C.), and the occurrence of cell cracking can be suppressed as much as possible. Further, in the power generation device 12, the air preheater 24 can efficiently recover the heat generated from the fuel cell stack 14, thereby reducing the temperature distribution of the fuel cell stack 14 and causing cell cracking due to thermal stress. You can avoid that.

  In addition, the power generation device 12 (fuel cell module 10) is free of residual high-temperature gas that has not been consumed in the power generation reaction described in, for example, a patent document “Japanese Patent Laid-Open No. 2006-86053” from the outer periphery of the power generation cell. An effect is also obtained when using a fuel cell stack having a structure that discharges to the outside. In this case, the high-temperature gas discharged from the fuel cell stack 14 burns as the remaining hydrogen gas and air react on the side surface on the discharge side. For this reason, the amount of air supplied to the air electrode 14b requires not only the amount necessary for the fuel cell reaction but also the amount of combustion, and the amount of preheating of the air is also large. Also in this respect, since the power generation device 12 includes the air preheater 24 that can efficiently preheat air to a desired temperature as described above, it can sufficiently cope with a large amount of preheating. Yes. In addition, the air preheater 24 uses the reaction heat from the fuel cell stack by disposing the second preheating portion 50b on the side where the exhaust gas of the fuel cell stack reacts and burns, and the air preheater 24 The heat exchanger efficiency can be further increased.

  In the air preheater 24, heat transfer fins 70, 76, and 86 are interposed in the air flow paths 66, 72, and 80, respectively. As a result, the heat transfer fins 70, 76, 86 function as baffle plates in the air flow paths 66, 72, 80, generating pressure loss in the air flowing through the air flow paths 66, 72, 80, and Can be evenly distributed in the width direction, and the flow rate is further improved, so that the heat exchange performance is improved.

  The heat transfer fin 70 of the first preheating part 50a constituting the main preheater 50 is welded and fixed to the partition wall 56 whose one end is on the high temperature side, and the heat transfer fin 76 of the second preheating part 50b is one end thereof. The portion is fixed by welding to the outer wall 78 on the high temperature side. Thereby, the radiant heat from the fuel cell stack 14 can be directly transmitted to the heat transfer fins 70 and 76 via the partition wall 56 and the outer wall 78, respectively, and a larger amount of heat transfer can be secured. Similarly, the heat transfer fin 86 of each auxiliary preheater 52 is also welded and fixed to the inner wall 81 on the high temperature side to secure a sufficient amount of heat transfer. Even when the air preheater 24 is formed of a thin plate to reduce the cost, the heat transfer fins 70, 76, 86 are appropriately fixed by welding, so that the structural strength and heat transfer performance can be improved. Similarly, the partition wall 56 is provided with bent pieces 56a and 56c at the upper and lower ends, and the heat transfer fins 70 are fixed by welding, so that the structural strength is higher than when a thin plate is used as a flat plate. .

  By the way, since the air preheater 24 has a shorter depth dimension than the height dimension and width dimension thereof, the main preheater 50 and the auxiliary preheater 52 each fall over in the back direction, and vibrations from connected devices. It is easy to move and shift due to (see FIG. 3). Therefore, in the present embodiment, the air preheater 24 is supported by the support base 85 having a function of suppressing the overturning and the positional deviation in the back direction.

  FIG. 10 shows a configuration example of the support base 85 for supporting the air preheater 24 in the heat insulating casing 16. The support base 85 includes a leg portion 87 and a holding portion 89 that holds the air preheater 24 at the upper portion of the leg portion 87. The leg portion 87 has a leg plate 87a that protrudes toward the front side (or the rear side), and is fixed on the floor surface of the heat insulating casing 16 by using an attachment hole 87b provided on the distal end side of the leg plate 87a. (See FIGS. 2 to 3). The holding unit 89 holds the air preheater 24 with a mounting surface 89 a that is the upper surface of the leg portion 87 and a holding surface 89 b that extends in the vertical direction.

  In the case of the present embodiment, the air preheater 24 includes a main preheater 50 and a pair of auxiliary preheaters 52. Therefore, as shown in FIG. 3, the left and right ends of the main preheater 50 are supported by a pair of support bases 85 with the leg plates 87a facing rearward (the main preheater 50 indicated by a two-dot chain line in FIG. 10). See also). Further, the auxiliary preheater 52 is supported by sandwiching the front and rear end portions thereof by a pair of support bases 85 with the leg plates 87a facing in the front-rear direction (see also the auxiliary preheater 52 indicated by a two-dot chain line in FIG. 10). ). Therefore, in the case of this embodiment, the air preheater 24 is supported using the six support bases 85.

  Since the support base 85 has the leg plate 87a that protrudes in the front-rear direction and lands on the floor in this manner, the rotational moment against the weight of the main preheater 50 and the auxiliary preheater 52 is improved, and the rearward direction is increased. Falling and misalignment are suppressed. In addition, although not shown in figure, the heat radiation of the air preheater 24 can be suppressed by arrange | positioning a heat insulating material so that it may be pinched | interposed between the main preheater 50 and the auxiliary preheater 52, and the support stand 85.

  As shown in FIG. 11, in the fuel cell module 10, a fuel cell stack 90 having one or a plurality of cylindrical power generation cells 90 a may be used instead of the fuel cell stack 14 described above. Also in this case, it is preferable that the air preheater 24 covers the three surfaces (the back surface and the left and right side surfaces) of the fuel cell stack 90. In some fuel cell stacks 90, the fuel can be internally reformed, and the reformer 22 may not be provided as shown in FIG. Further, in the case of a configuration using such a cylindrical power generation cell, the fuel cell stack 90 may be circular instead of rectangular in plan view. In this case, air preheating as indicated by a two-dot chain line in FIG. The vessel 24 may be constituted by a fan-shaped (or circular) main preheater 50.

  It should be noted that the present invention is not limited to the above-described embodiment, and it is needless to say that the present invention can be freely changed without departing from the gist of the present invention.

  For example, in the above embodiment, the configuration in which the fuel cell stacks 14 are used as one set of four or one set is illustrated, but it goes without saying that the number of the fuel cell stacks 14 can be changed as appropriate.

DESCRIPTION OF SYMBOLS 10 Fuel cell module 12 Power generator 14,90 Fuel cell stack 14a Fuel electrode 14b Air electrode 16 Heat insulation housing 22 Reformer 24 Air preheater 26 Vaporizer 40 Shelf device 40a Upper shelf 40b Lower shelf 50 Main preheater 50a 1st preheating Part 50b Second preheating part 52 Auxiliary preheater 54, 55 Bridge 56 Bulkhead 66, 72, 80 Air flow path 70, 76, 86 Heat transfer fins 71, 78 Outer wall 81 Inner wall 85 Support base 87 Leg part 89 Holding part LA1, LA2 Air supply line LF1, LF2 Fuel supply line W Welded part

Claims (16)

An air preheater that is provided in a fuel cell module surrounded by a heat insulating casing and preheats air supplied to the fuel cell stack,
A first preheating unit for preheating by circulating air introduced from the outside of the heat insulating housing;
A second preheating part through which air after passing through the first preheating part flows;
An air preheater comprising: The air preheater according to claim 1,
The air preheater, wherein the second preheating part is arranged closer to the fuel cell stack than the first preheating part. The air preheater according to claim 1 or 2,
The first preheating unit causes air introduced from the outside of the heat insulating housing to flow through a first air flow path formed between a partition wall that partitions the second preheating unit and a first outer wall. Preheat,
The second preheating unit further preheats the air flowing out from the first preheating unit by passing it through a second air flow path formed between the partition wall and a second outer wall disposed opposite to the fuel cell stack. And supplying the fuel cell stack with an air preheater. The air preheater according to any one of claims 1 to 3,
The air preheater, wherein the first preheating unit and the second preheating unit preheat the air supplied to the fuel cell stack using radiant heat from the fuel cell stack. The air preheater according to claim 3, wherein
An air preheater in which heat transfer fins are provided in the first air flow path and the second air flow path. The air preheater according to claim 5,
One end of the heat transfer fin of the first air channel is fixed to the partition wall,
One end of the heat transfer fin of the second air flow path is fixed to the inner surface of the second outer wall. In the air preheater according to any one of claims 1 to 6,
A main preheater having the first preheating part and the second preheating part;
An auxiliary preheater that is provided separately from the main preheater, further preheats the air flowing out of the first preheater and flows into the second preheater;
An air preheater comprising: The air preheater according to claim 7,
A plurality of the auxiliary preheaters are provided,
A plurality of air outlets are provided in the first preheating part and a plurality of air inlets are provided in the second preheating part so as to respectively correspond to the plurality of auxiliary preheaters. Preheater. A fuel cell stack;
An air preheater for preheating air supplied to the fuel cell stack;
A heat insulating enclosure surrounding the fuel cell stack and the air preheater;
A power generation device including a fuel cell module having
The air preheater has a first preheating unit that preheats air introduced from the outside of the heat insulating casing through a first air flow path formed between the partition wall and the first outer wall;
The air that has flowed out of the first preheating part is circulated through a second air flow path formed between the partition wall that partitions the first preheating part and a second outer wall that is disposed to face the fuel cell stack. And a second preheating unit for further preheating and supplying the fuel cell stack. The power generator according to claim 9, wherein
The air preheater preheats the air supplied to the fuel cell stack using radiant heat from the fuel cell stack. The power generator according to claim 10, wherein
A main preheater having the first preheating part and the second preheating part;
A plurality of auxiliary preheaters that are provided separately from the main preheater, and further preheat air flowing out from the first preheater to flow into the second preheater,
The first preheating unit is provided with a plurality of air outlets and the second preheating unit is provided with a plurality of air inlets so as to correspond to the plurality of auxiliary preheaters, respectively. apparatus. The power generator according to claim 11,
Two auxiliary preheaters are provided,
The air outlets are provided on both side surfaces of the first preheating part,
The air inlet is provided on each side of the second preheating part,
The two auxiliary preheaters are installed on opposing surfaces of the fuel cell stack, respectively. In the electric power generating apparatus of any one of Claims 9-12,
The fuel cell stack is a solid oxide fuel cell. The power generator according to claim 13,
The solid oxide fuel cell has a rectangular parallelepiped shape in which rectangular flat plates are stacked. The power generator according to claim 13 or 14,
The solid oxide fuel cell is arranged in a plurality of stages above and below, and has a structure in which a plurality of solid oxide fuel cells are installed in each stage. In the electric power generating apparatus of any one of Claims 13-15,
The fuel cell module further includes a reformer that reforms the fuel introduced into the fuel cell stack and a vaporizer that generates water vapor introduced into the reformer inside the heat insulating casing. Have
Sandwiching the fuel cell stack, the reformer is installed on the side facing the main preheater,
The power generator, wherein the vaporizer is installed above the fuel cell stack.

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