JP2010040313A - Fuel cell module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a reformer unit for a fuel cell capable of improving the stability of a combustion state. <P>SOLUTION: The reformer unit for a fuel cell includes: a plurality of fuel cells 4 each of which contains a fuel gas duct, emits a surplus fuel gas from an outlet of the fuel gas duct, and composes a fuel cell assembly 401; the reformer 5 which is disposed above the fuel cell assembly 401 and reforms a gas to be reformed to be a fuel gas; a detector which detects the temperature of the reformer 5; and a controller which controls feeding so that only the gas to be reformed and water vapor are fed to the reformer 5 when the detector detects that the reformer 5 has a temperature capable of steam reforming. A combustion section 18 for mixing and combusting the fuel gas reformed by the reformer 5 and an oxidant gas is formed in the upper part of the plurality of fuel cells 4. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a fuel cell module used in a solid oxide fuel cell (SOFC).

  Conventionally, in such a fuel cell module, a plurality of fuel cells that have a fuel gas channel inside and discharge excess fuel gas from the outlet of the fuel gas channel, and constitute a fuel cell assembly, And at least one reformer which is disposed on the upper part of the fuel cell assembly and reforms the gas to be reformed into fuel gas (see, for example, Patent Documents 1 to 3 below). In Patent Documents 1 to 3 (Japanese Patent Laid-Open Nos. 2002-289244, 2005-183375, and 2007-242626), a fuel cell in the upper part of the outlet of the fuel gas flow path of the fuel cell. Excess fuel gas discharged from the outlet of the fuel gas flow path is burned together with the oxidant gas. Thus, the reformer is heated to promote the reforming reaction in the reformer.

  In Patent Document 2 (Japanese Patent Laid-Open No. 2005-183375), an ignition heater for igniting surplus fuel gas discharged from the fuel cell is further provided, and a partial oxidation reforming process and an autothermal reforming process. And the ignition heater is started and stopped for each steam reforming step. Thereby, the starting property in each reforming process is made favorable, and the occurrence of misfire is suppressed.

JP 2002-289244 A JP 2005-183375 A JP 2007-242626 A

  By the way, in the steam reforming step, only the reformed gas and steam are supplied to the reformer, and the steam reforming reaction proceeds. Since this steam reforming reaction is a so-called endothermic reaction, the combustion state in the vicinity of the reformer in the combustion section may become unstable. Since the end of the fuel cell assembly in the combustion portion in the arrangement direction of the fuel cells is located at the end of the combustion flame, the temperature is relatively low. For this reason, the combustion state tends to become more unstable at the end of the fuel cell assembly in the combustion portion in the arrangement direction of the fuel cells. On the other hand, in the center part in the arrangement direction of the fuel cells in the fuel cell assembly in the combustion part, the temperature is relatively high because it is located in the center part of the combustion flame. For this reason, the combustion state tends to be stable in the central portion of the fuel cell assembly in the combustion portion in the arrangement direction of the fuel cells.

  Therefore, an object of the present invention is to provide a fuel cell module capable of improving the stability of the combustion state in the combustion section.

In order to solve the above-described problems, a fuel cell module according to the present invention includes a plurality of fuel gas cell assemblies that have a fuel gas flow channel therein and discharge residual fuel gas from an outlet of the fuel gas flow channel. A fuel cell of
A reformer unit for a fuel cell, which is disposed above the fuel cell assembly and includes at least one reformer including a reforming catalyst that reforms the gas to be reformed into fuel gas. A fuel cell module for
The reformer is configured to supply only the gas to be reformed and steam when it is detected that the temperature is capable of steam reforming,
On the upper part of the plurality of fuel cells, a combustion part is formed in which the remaining fuel gas that did not contribute to the power generation reaction and the remaining oxidant gas are mixed and burned,
The reforming catalyst on the upstream side of the reformer is disposed outside the fuel cells located at the ends of the plurality of fuel cells in the fuel cell assembly,
The reforming catalyst on the upstream side of the reformer is a fuel cell module that is close to a side wall of the power generation chamber.

  ADVANTAGE OF THE INVENTION According to this invention, the fuel cell module which can improve the stability of the combustion state in a combustion part can be provided.

  Prior to describing the best mode for carrying out the present invention, the function and effect of the present invention will be described.

A fuel cell module according to the present invention includes a plurality of fuel cells that have a fuel gas flow channel therein and discharge remaining fuel gas from an outlet of the fuel gas flow channel to constitute a fuel cell assembly.
A reformer unit for a fuel cell, which is disposed above the fuel cell assembly and includes at least one reformer including a reforming catalyst that reforms the gas to be reformed into fuel gas. A fuel cell module for
The reformer is configured to supply only the gas to be reformed and steam when it is detected that the temperature is capable of steam reforming,
On the upper part of the plurality of fuel cells, a combustion part is formed in which the remaining fuel gas that did not contribute to the power generation reaction and the remaining oxidant gas are mixed and burned,
The reforming catalyst on the upstream side of the reformer is disposed outside the fuel cells located at the ends of the plurality of fuel cells in the fuel cell assembly,
The reforming catalyst on the upstream side of the reformer is close to a side wall of the power generation chamber.

  In the present invention, when it is detected that the reformer is at least at a temperature at which steam reforming is possible, only the gas to be reformed and steam are supplied to perform the steam reforming reaction. Since the steam reforming reaction is an endothermic reaction, the heat of the combustion section is taken away. However, since the reforming catalyst included in the reformer is arranged outside the end in the arrangement direction of the plurality of fuel cells in the fuel cell assembly, the arrangement of the plurality of fuel cells in the combustion section It is hard to take heat at the end in the direction. For this reason, it can suppress that the combustion state in the edge part in the sequence direction of the some fuel cell in a combustion part becomes unstable. In the central part in the arrangement direction of the plurality of fuel cells in the combustion part, heat is taken away by the reforming catalyst, but the combustion state becomes unstable because the temperature is originally high and the combustion state is good. There is no drowning. As a result, the stability of the combustion state in the combustion section is improved.

  Furthermore, since the reforming catalyst on the upstream side of the reformer is close to the side wall of the power generation chamber, heat from the combustion section can be received by convection, so that the reforming catalyst reaction functions sufficiently.

  The fuel cell module according to the present invention further includes a reformed gas supply pipe that supplies the reformed gas to be reformed by the reformer to the reformer, and the reformed gas supply pipe includes It is also preferable that the reformer is disposed in a projection region toward the plurality of fuel cells. Since the reformed gas supply pipe is disposed in the projection region of the reformer on the fuel cell side, the reformed gas supply pipe is disposed closer to the fuel cell and thus the combustion portion. . Thereby, the to-be-reformed gas supply pipe receives the heat of the combustion section and is heated, so that the heat of the combustion section can be effectively used.

  In the fuel cell module according to the present invention, it is also preferable that the amount of the reforming catalyst in the reformer is decreased from the upstream side toward the downstream side while the amount of the reforming catalyst is inclined. Since the amount of the reforming catalyst is inclined from the upstream side toward the downstream side, it is possible to promote the reforming reaction on the upstream side and reduce the reforming reaction toward the downstream side. In other words, the endothermic reaction is large on the upstream side, and the endothermic reaction can be reduced toward the downstream side. Since the endothermic reaction can be reduced toward the downstream side, it is possible to prevent the combustion state at the end in the arrangement direction of the plurality of fuel cells in the combustion portion from becoming unstable. Further, even if the endothermic reaction is increased on the upstream side, the reforming catalyst reaction functions sufficiently because it is close to the side wall of the power generation chamber, so that heat in the combustion section can be received by convection.

  In the fuel cell module according to the present invention, it is also preferable that the reforming catalyst is intermittently filled from the upstream side to the downstream side in the reformer. Since the reforming catalyst is filled intermittently, the endothermic reaction can be made intermittent. For this reason, it is possible to easily design and manage a configuration in which the reforming catalyst can be charged intermittently while avoiding the region where the combustion state at the end in the arrangement direction of the plurality of fuel cells in the combustion portion becomes unstable. .

In the fuel cell module according to the present invention, it is also preferable that the plurality of fuel cells are arranged in a matrix in the fuel cell assembly. In this preferred embodiment,
A configuration in which the reformer is disposed outside the end portions in the arrangement direction of the plurality of fuel cells in the fuel cell assembly can be easily designed and managed.

  DESCRIPTION OF EXEMPLARY EMBODIMENTS Hereinafter, preferred embodiments of the invention will be described with reference to the accompanying drawings. In order to facilitate the understanding of the description, the same components are denoted by the same reference numerals as much as possible in the drawings, and redundant descriptions are omitted.

  FIG. 1 is a front view showing an embodiment of a fuel cell module according to the present invention. FIG. 2 is a perspective view of the fuel cell module with the cover member removed.

  As shown in the figure, the fuel cell module FC has ten fuel cell stacks 400 arranged side by side in a space sealed by the cover member 1 and the base member 2. Therefore, in the fuel cell module FC, the cover member 1 and the base member 2 form a container that contains the fuel cell 4 and the like. In each fuel cell stack 400, 16 fuel cells 4 are arranged in two rows. These fuel cells 4 are electrically arranged in series. The fuel cell module FC of this embodiment includes a fuel cell reformer unit.

  In the fuel cell module FC, a fuel cell assembly 401 is constituted by ten fuel cell stacks 400. In the fuel cell assembly 401, 160 fuel cells 4 are arranged in a matrix. In the present embodiment, the fuel cells 4 are arranged in 8 rows × 20 columns.

  Each fuel battery cell 4 has a tubular shape, and a gas flowing from one end of the fuel battery cell 4 to the other end inside the pipe of the fuel battery cell 4 and outside the pipe from the one end to the other end. It operates by the action of the gas flowing to the part. In the present embodiment, the gas flowing in the pipe of the fuel battery cell 4 is a fuel gas such as reformed gas obtained by reforming hydrogen or hydrocarbon fuel, and the gas flowing outside the pipe of the fuel battery cell 4 contains oxygen. Contains oxidant gas such as air.

  The fuel cell unit 30 will be described with reference to FIG. As shown in FIG. 3, the fuel cell unit 30 is a tubular structure formed by the fuel cells 4 and extending in the vertical direction, and includes a cylindrical fuel cell 4 and one end of the fuel cell 4. It has an inner electrode terminal 40 attached to 4a and an outer electrode terminal 42 attached to the other end 4b.

  The fuel cell 4 includes a cylindrical inner electrode layer 44, a cylindrical outer electrode layer 48, a cylindrical electrolyte layer 46 disposed between the electrode layers 44, 48, and an inner electrode. And a through flow channel 50 configured inside the layer 44. Further, an inner electrode exposed peripheral surface 44a in which the inner electrode layer 44 is exposed to the electrolyte layer 46 and the outer electrode layer 48 at one end 4a of the fuel cell 4, and the electrolyte layer 46 is an outer electrode layer. An electrolyte exposed peripheral surface 46 a exposed to 48 is provided. The other end 4b of the fuel cell 4 is configured by an outer electrode exposed peripheral surface 48a from which the outer electrode layer 48 is exposed. The through channel 50 functions as a fuel gas channel. The inner electrode exposed peripheral surface 44 a is also an inner electrode outer peripheral surface that is in electrical communication with the inner electrode layer 44. The outer electrode exposed peripheral surface 48 a is also an outer electrode outer peripheral surface that is in electrical communication with the outer electrode layer 48.

  The inner electrode layer 44 includes, for example, a mixture of Ni and zirconia doped with at least one selected from rare earth elements such as Ca, Y, and Sc, ceria doped with at least one selected from Ni and rare earth elements, And a mixture of Ni and lanthanum gallate doped with at least one selected from Sr, Mg, Co, Fe, and Cu. The electrolyte layer 46 includes, for example, zirconia doped with at least one selected from rare earth elements such as Y and Sc, ceria doped with at least one selected from rare earth elements, lanthanum gallate doped with at least one selected from Sr and Mg, Formed from at least one of the following. The outer electrode layer 48 is made of, for example, lanthanum manganite doped with at least one selected from Sr and Ca, lanthanum ferrite doped with at least one selected from Sr, Co, Ni, and Cu, Sr, Fe, Ni, and Cu. It is formed from at least one selected from samarium cobalt and silver doped with at least one selected. In this case, the inner electrode layer 44 becomes a fuel electrode, and the outer electrode layer 48 becomes an air electrode. The thickness of the inner electrode layer 44 is, for example, 1 mm, the thickness of the electrolyte layer 46 is, for example, 30 μm, the thickness of the outer electrode layer 48 is, for example, 30 μm, and the outer diameter is For example, it is 1-10 mm.

  The inner electrode terminal 40 is arranged so as to cover the inner electrode exposed peripheral surface 44a from the outside over the entire circumference and is electrically connected to the inner electrode terminal 40a, and a tubular shape extending from the main body portion 40a in the longitudinal direction of the fuel cell 4. Part 40b. The main body portion 40a and the tubular portion 40b are cylindrical and concentrically arranged, and the tube diameter of the tubular portion 40b is smaller than the tube diameter of the main body portion 40a. The tubular portion 40b has a connection channel 40c that communicates with the through channel 50 and communicates with the outside. A step portion 40 d between the main body portion 40 a and the tubular portion 40 b is in contact with the end surface 44 b of the inner electrode layer 44.

  The outer electrode terminal 42 is disposed so as to cover the outer electrode exposed peripheral surface 48a from the outside over the entire circumference and is electrically connected thereto, and a tubular shape extending from the main body portion 42a in the longitudinal direction of the fuel cell 4. Part 42b. The main body portion 42a and the tubular portion 42b are cylindrical and concentric, and the tube diameter of the tubular portion 42b is smaller than the tube diameter of the main body portion 42a. The tubular portion 42b has a connection channel 42c that communicates with the through channel 50 and communicates with the outside. A step portion 42 d between the main body portion 42 a and the tubular portion 42 b is in contact with the outer electrode layer 48, the electrolyte layer 46, and the end surface 44 c of the inner electrode layer 44 via the annular insulating member 52.

  The overall shape of the inner electrode terminal 40 and the overall shape of the outer electrode terminal 42 are the same. Further, the inner electrode terminal 40 and the fuel battery cell 4, and the outer electrode terminal 42 and the fuel battery cell 4 are sealed and fixed by a conductive sealing material 54 over the entire circumference. The sealing material 54 is various brazing materials including, for example, silver, a mixture of silver and glass, gold, nickel, copper, and titanium.

  The connection flow path 40 c of the inner electrode terminal 40, the through flow path 50 of the fuel cell 4, and the connection flow path 42 c of the outer electrode terminal 42 constitute an in-pipe flow path 30 c of the fuel cell unit 30.

  Next, the fuel cell stack 400 will be described with reference to FIG. The fuel cell stack 400 includes 16 fuel cell units 30, an upper support plate 400a, a lower support plate 400b, a connection member 400c, and an external terminal 400d.

  The upper support plate 400a and the lower support plate 400b are rectangular, and are through holes (fitting holes) that fit into the tubular portions 40b and 42b of the fuel cell unit 30 so as to support the fuel cell unit 30 in 2 columns × 8 rows, respectively. (Not shown in the figure). The upper support plate 400a and the lower support plate 400b are formed of an electrically insulating material, for example, formed of heat resistant ceramics. Specifically, it is preferable to use alumina, zirconia, spinel, forsterite, magnesia, titania or the like.

  The 16 fuel cell units 30 are arranged so that they are electrically connected in series. Specifically, the fuel cell units 30 are arranged so that the inner electrode terminals 40 of the adjacent fuel cell units 30 are alternately arranged on the upper side and the lower side. Further, a connection member 400c for electrically connecting the 16 fuel cell units 30 in series is provided. The connection member 400c electrically connects one adjacent inner electrode terminal 40 and one outer electrode terminal 42. Each of the inner electrode terminal 40 and the outer electrode terminal 42 at both ends of the 16 fuel cell units 30 connected in series is provided with an external terminal 400d for electrical connection with the outside. The connection member 400c and the external terminal 400d are made of, for example, a heat-resistant metal such as stainless steel, a nickel base alloy, or a chromium base alloy, or a ceramic material such as lanthanum chromite. The external terminals 400d of each fuel cell stack 400 are electrically connected in series, and are connected to the electrode rods 13 and 14 at both ends thereof.

  As described with reference to FIGS. 3 and 4, in the fuel cell stack 400, the end 4a of the fuel cell unit 30 where the inner electrode terminal 40 is provided and the end where the outer electrode terminal 42 is provided. The parts 4b are arranged so as to alternate with each other. Accordingly, when the gas flow inside and outside the fuel cell 4 is described with reference to FIG. 1, the one end 4 </ b> A is disposed on the gas tank 3 side of the end 4 a and the end 4 b of the fuel cell 4. The other end 4B indicates the end portion disposed on the reformer 5 side among the end portion 4a and the end portion 4b of the fuel cell 4.

  Returning to FIG. 1, the fuel cell module FC will be described. The cover member 1 is formed in a rectangular parallelepiped shape by a side wall (not shown) on the front side, side walls 101 and 102 in the arrangement direction of the fuel cell units 30, a side wall 103 on the back side, and a ceiling 104. A flange portion 1 a is formed at the lower end portion of the side wall 101. By bringing the flange portion 1 a of the cover member 1 into contact with the base member 2, a space sealed by the cover member 1 and the base member 2 is formed.

  An internal space formed by the cover member 1 and the base member 2 is separated into two spaces by a partition plate 15. Among the spaces separated by the partition plate 15, the space where the fuel cell stack 400 is disposed is the power generation chamber 16. Of the spaces separated by the partition plate 15, the other space is an exhaust gas chamber 17.

  Therefore, in this embodiment, the power generation chamber 16 and the exhaust gas chamber 17 are formed by the cover member 1 and the base member 2.

  The gas tank 3 is placed on the partition plate 15. Ten fuel cell stacks 400 are arranged side by side in the gas tank 3, and fuel gas is supplied from the gas tank 3 to the fuel cell 4 constituting each fuel cell stack 400.

  More specifically, an opening (not shown) having substantially the same shape as the lower support plate 400b of the fuel cell stack 400 is provided on the upper surface of the gas tank 3, and the lower support plate 400b is in close contact with the opening. Thus, the gas tank 3 and each fuel cell stack 400 are connected. Therefore, the fuel cells 4 constituting the fuel cell stack 400 are erected on the gas tank 3 with their tip portions facing upward.

  On the other hand, above each fuel cell assembly 401 is a combustion section 18 in which air and fuel gas are mixed and burned. The fuel gas rises from the gas tank 3 through the in-pipe flow path 30 c of the fuel cell unit 30 toward the combustion unit 18. Further, the air flowing outside the fuel cell 4 also rises toward the combustion unit 18. An ignition device 19 for starting combustion of combustion gas and air is provided in a portion corresponding to the combustion unit 18 in the rear side wall 102. The ignition device 19 mixes and burns fuel gas and air. The fuel cells 4 constituting the fuel cell assembly 401 are heated from above by the combustion unit 18.

  Here, the positional relationship between the reformer 5 and the fuel cell assembly 401 (fuel cell 4) will be described with reference to FIG. The reformer 5 is disposed on the inner side of the end 401a in the arrangement direction of the fuel cells 4 in the fuel cell assembly 401. In the present embodiment, among the fuel cells 4 arranged in 8 rows × 20 columns, the fuel cells 4 in two columns (total of 4 columns) positioned at both ends in the row direction are exposed in a top view. A reformer 5 is arranged. That is, the reformer 5 is arranged on the upper part of the four rows of fuel cells 4 located at the center in the row direction so as to cover these fuel cells 4. The width of the reformer 5 in the row direction in the arrangement of the fuel cells 4 is set to be narrower than the width of the fuel cell assembly 401 in the row direction.

  Further, in the longitudinal direction of the reformer, the reforming catalyst on the upstream side of the reformer in which a pipe 6A, which will be described later in the figure, is disposed, is positioned at the ends of the plurality of fuel cells in the fuel cell assembly. It arrange | positions in the upper surface view outer side rather than the fuel battery cell 401 to perform.

  The reforming catalyst on the upstream side of the reformer is close to the side wall 102 of the power generation chamber.

  The fuel gas is introduced into the fuel cell module FC through the fuel gas supply pipe 8. The fuel gas supply pipe 8 is connected to the reformer 5 via a pipe 6 </ b> A (reformed gas supply pipe) provided upright with respect to the partition plate 15. An air supply pipe (not shown) is also connected to the pipe 6A (the reformer 5). The fuel gas supply pipe 8 and the air supply pipe are joined before being connected to the pipe 6A, and the reformer 5 is configured to be able to supply a premixed fuel gas and air. Although not explicitly shown in FIGS. 1 to 3, in this embodiment, an electromagnetic valve is attached to each of the fuel gas supply pipe 8 and the air supply pipe, and each electromagnetic valve is an instruction output from a CPU as a control unit. It is configured so that it can be opened and closed in response to a signal and the ratio of fuel gas to air supplied to the reformer 5 can be changed.

  The fuel gas (which may be mixed with water vapor) and air (which may be only fuel gas) introduced into the reformer 5 is reformed by the reforming catalyst contained in the reformer 5. Is done. The reformed fuel gas and air are supplied to the gas tank 3 through the pipe 6B. The portion where the pipe 6A is connected to the reformer 5 and the portion where the pipe 6B is connected to the reformer 5 are separated from each other in the vicinity of one end and the other end in the longitudinal direction. As a result, the fuel gas and air supplied to the reformer 5 can sufficiently come into contact with the reforming catalyst. Further, as shown in FIGS. 2 and 5, the pipes 6 </ b> A and 6 </ b> B are provided in a straight line in the projection region S of the reformer 5 when viewed from the longitudinal direction of the fuel cell 4. That is, the pipes 6 </ b> A and 6 </ b> B are provided in a region that does not protrude from the reformer 5 when viewed from above the reformer 5.

  A reforming catalyst is enclosed in the reformer 5. As the reforming catalyst, a catalyst in which nickel is applied to the surface of the alumina sphere and a catalyst in which ruthenium is applied to the surface of the alumina sphere are appropriately used. These reforming catalysts are spheres.

  Part of alumina spheres may be enclosed in the reformer 5 as a filler for the purpose of adjusting the amount of reforming catalyst. The filling material shape is preferably a sphere, pellet, powder, fiber, honeycomb or the like. Specific examples of filler materials include ceramics such as alumina, zirconia, spinel, forsterite, magnesia, and titania, refractory metals such as stainless steel, nickel-base alloys, and chromium-base alloys, nickel, aluminum, gold, silver, It is preferable to use a single metal such as copper.

  Increasing the amount of the reforming catalyst can be achieved by adjusting the mixing ratio of the reforming catalyst and the filler.

  In order to fill the amount of the reforming catalyst intermittently, it can be achieved by dividing and filling the region in which only the reforming catalyst is filled and the region in which only the filling material is filled.

  Further, the side walls 101, 102, 103 and the ceiling 104 of the cover member 1 have a double wall structure, and are configured so that gas can pass through the space between the double walls. The internal space of the side wall 102, the internal space of the ceiling 104, and the internal space of the side wall 103 are connected to each other. An air supply pipe 10 is communicated with the lower portion of the side wall 102 so that air is supplied.

  The air supplied to the side wall 102 flows from the ceiling 104 to the side wall 103, and is heated by heat transmitted from the power generation chamber 16 in the flow process. The air that has flowed into the side wall 103 is configured to flow into the air flow path 103a. The air channel 103 a is formed so as to extend from the side wall 101 toward the side wall 102, and is disposed along the vicinity of the upper surface of the partition plate 15 inside the side wall 103. The air flow path 103a is provided with air inflow holes 103b at a predetermined interval.

  The air that flows into the air flow path 103a from the side wall 103 is configured to flow into the power generation chamber 16 through the air inflow hole 103b. The air that has flowed into the power generation chamber 16 through the air inflow hole 103 b flows from the lower side to the upper side of each fuel cell 4 through the passage T outside the fuel cell 4. The air that reaches the upper side of each fuel battery cell 4 is burned together with the fuel gas that has passed through the pipe flow path of each fuel battery cell 4.

  On the inner side of the side wall 102, an orienting portion 20A for directing the air flowing upward from the lower side of each fuel cell 4 to the combustion portion 18 through the air inflow hole 103b is provided adjacent to the pipe 6A. More specifically, the directing portion 20A is a side wall 102, and the side wall 102 is provided close to the pipe 6A.

  A similar structure is also provided on the inner side of the side wall 101. That is, an orientation portion 20B for bringing the air flowing upward from the lower side of each fuel battery cell 4 closer to the combustion portion 18 is also provided inside the side wall 102 adjacent to the pipe 6B. More specifically, the directing portion 20B is a side wall 101, and the side wall 101 is provided close to the pipe 6B. By such directing portions 20 </ b> A and 20 </ b> B, the air flowing upward from the lower side of each fuel cell 4 is restricted in the projection region S of the reformer 5 in the width direction of the fuel cell unit 30.

  An exhaust gas outflow slit 103 c is provided at the inner upper end of the side wall 103. Exhaust gas generated by combustion of fuel gas and air above each fuel cell 4 enters the internal space of the side wall 103 through the exhaust gas outflow slit 103c. The exhaust gas that has entered the side wall 103 flows downward through the internal space of the side wall 103, reaches the exhaust gas chamber 17, and is temporarily stored. The exhaust gas that has reached the exhaust gas chamber 17 is discharged to the outside of the fuel cell module FC through the exhaust gas pipe 11.

  Next, the configuration of the fuel cell FCS using the fuel cell module FC will be described with reference to FIG. FIG. 6 is a block diagram showing the configuration of the fuel cell FCS. As shown in FIG. 6, the fuel cell FCS includes a fuel cell module FC, a fuel supply unit FP, an air supply unit AP, a water supply unit WP, a power extraction unit EP, and a detection unit TD (detection unit). And a control unit CS (control unit). The fuel supply unit FP, the air supply unit AP, the water supply unit WP, and the power extraction unit EP constitute an auxiliary device AD of the fuel cell FCS.

  The fuel supply unit FP is a part that supplies city gas as fuel gas from a city gas pipe serving as a fuel supply source to the fuel cell module FC, and includes a fuel pump and a solenoid valve. The fuel gas supplied from the fuel supply unit FP is sent out to the fuel gas supply pipe 8. The fuel supply unit FP also has an air blower for supplying air mixed with city gas.

  The air supply unit AP is a part that supplies air from the atmosphere as an air supply source to the fuel cell module FC, and includes an air blower and an electromagnetic valve. The air supplied from the air supply unit AP is sent out to the air supply pipe 10.

  The water supply unit WP is a part that supplies water from a water pipe as a water supply source to the fuel cell module FC, and includes a water pump and an electromagnetic valve. The water supplied from the water supply unit WP is converted into water vapor inside the fuel cell module FC and sent out to a water vapor supply pipe (not shown).

  The power extraction unit EP is a part that extracts electric power from the fuel cell module FC, and includes a power conversion device such as an inverter. The power extraction unit EP is connected to the electrode rods 13 and 14, and the converted power is configured to be sent to a power supply destination.

  The detection unit TD detects the temperature of the reformer 5 and outputs a signal indicating the temperature of the reformer 5 to the control unit CS. The control unit CS is a part for controlling each of the fuel supply unit FP, the air supply unit AP, the water supply unit WP, and the power extraction unit EP, and includes a CPU and a ROM. The operation of the fuel cell module FC as described above is executed based on an instruction signal from the control unit CS. The controller CS controls the reformer 5 to supply only the gas to be reformed and the steam when at least the detector TD detects that the reformer 5 has a temperature capable of steam reforming. Thereby, in the reformer 5, an autothermal reforming reaction described later proceeds.

  Next, the operation of the fuel cell including the fuel cell module FC according to the present embodiment and the operation method thereof will be described with reference to FIG. In the following description, for the sake of convenience, the operation of the fuel cell module FC is described to describe the fuel cell including the fuel cell module FC.

  The operation method of the fuel cell module FC according to the present embodiment includes an ignition process, a reforming process, a gas supply process, a cell operation process, and a combustion process. As will be described later, these steps are not necessarily executed sequentially, but are executed in parallel or executed in a different order.

  First, in order to warm the fuel cell module FC, fuel gas and air are supplied to the fuel cell module FC without applying a load to the circuit including the fuel cell module FC, that is, with the circuit including the fuel cell module FC open. Supply. At this stage, even if fuel gas and air are present, no current flows through the circuit, so the fuel cell module FC does not generate power.

  Specifically, fuel gas is supplied. Specifically, the fuel gas is supplied from the fuel supply unit FP to the fuel gas supply pipe 8. At this time, the control unit CS outputs a signal to a fuel pump, an air blower of the fuel supply unit FP, and the like so as to supply city gas and fuel gas including air. FIG. 7 shows the control voltage of the fuel pump and the control voltage of the air blower of the fuel supply unit FP. The fuel gas supplied from the fuel gas supply pipe 8 is stored in the gas tank 3. Thereby, uniform and uniform supply of fuel gas to each fuel cell unit 30 is ensured. The fuel gas accumulated in the gas tank 3 flows through the in-pipe channel 30 c of the fuel cell unit 30 and acts on the inner electrode layer 44. The fuel gas that did not act reaches the upper space of each fuel cell unit 30.

  In addition, air in the atmosphere is supplied. Specifically, the air is supplied to the air supply pipe 10 by the air supply unit AP and flows from the side wall 102 to the ceiling 104 and the side wall 103. Next, the air is introduced into the power generation chamber 16 from the air inflow holes 103c and 103d through the air flow paths 103a and 103b. The air guided into the power generation chamber 16 acts on the outer electrode layer 48. The air that did not act reaches above each fuel cell unit 30 (fuel cell 4).

  Next, the ignition device 19 is used to burn the combustion gas and air (ignition process, combustion process). The exhaust gas generated thereby becomes high temperature. The exhaust gas is guided to the internal space of the side walls 104 and 105 and flows into the exhaust gas chamber 17. Exhaust gas flowing into the exhaust gas chamber 17 is discharged from the exhaust gas pipe 11.

  When the fuel gas and air burn, the temperature in the power generation chamber 16 is raised. While the air introduced from the outside flows through the side wall 102, the ceiling 104, and the side wall 103, the air is heated by exchanging heat with the power generation chamber 16. The hot exhaust gas flows into the exhaust gas chamber 17 and raises the temperature in the exhaust gas chamber 17. Since the reformer 5 is provided inside the exhaust gas chamber 17, the temperature of the reformer 5 is also raised.

  Subsequently, a gas obtained by mixing hydrocarbon-based city gas and air in advance is supplied to the reformer 5 (reforming step). In the reformer 5, the partial oxidation reforming reaction POX of the formula (1) proceeds. Since this partial oxidation reforming reaction is an exothermic reaction, the startability is good, and further, heat is transferred from the reformer 5 to the power generation chamber 16 via the partition plate 15. Accordingly, the fuel battery cell 4 constituting the fuel battery cell stack 400 is heated by heat from the mixed combustion of fuel gas and air from above and is heated by this heat transfer from below, so that it is sandwiched between the heating portions. Thus, a uniform temperature increase is possible. Even if the partial oxidation reforming reaction POX proceeds, the combustion reaction continues in the combustion section 18.

_{C m H n + m / 2} O 2 → m CO + n H 2 (1)

  After a predetermined time has elapsed since the execution of the partial oxidation reforming reaction POX, a gas in which city gas, air, and water vapor are mixed in advance is supplied to the reformer 5 (reforming step). At this time, the control unit CS outputs a signal to a fuel pump, an air blower of the fuel supply unit FP, a water pump, and the like so as to supply water vapor in addition to city gas and fuel gas including air. FIG. 7 shows the control voltage of the water pump. In the reformer 5, an autothermal reforming reaction ATR in which the partial oxidation reforming reaction POX described above and a steam reforming reaction SR described later are used together proceeds. Since the autothermal reforming reaction ATR is thermally balanced internally, the reaction proceeds in the reformer 5 while being thermally independent. That is, heat generation by the partial oxidation reforming reaction POX is dominant when there is a large amount of oxygen, and heat absorption by the steam reforming reaction SR is dominant when there is a lot of water vapor. At this stage, the initial stage of activation has already passed, and the temperature inside the power generation chamber 16 has been raised to a certain temperature. Therefore, even if the endothermic reaction is dominant, the temperature does not drop significantly. Even if the autothermal reforming reaction ATR proceeds, the combustion reaction continues in the combustion section 18.

  When a predetermined time has elapsed after the start of the execution of the autothermal reforming reaction, when the reformer 5 detects that the reformer 5 has a temperature capable of steam reforming, the gas mixed with city gas and steam in advance is reformed. Supply to vessel 5 (reforming step). At this time, the control unit CS outputs a signal to the fuel pump, the water pump, etc. and supplies a signal to stop the air blower of the fuel supply unit FP so as to supply water vapor in addition to the fuel gas containing only city gas. Output.

  In the reformer 5, the steam reforming reaction SR of the formula (2) proceeds. Since this steam reforming reaction SR is an endothermic reaction, the reaction proceeds while maintaining a heat balance by the combustion heat from the combustion section 18. At this stage, since the power generation chamber 16 has already been heated to a sufficiently high temperature since it is already the final stage of start-up, there is no significant temperature drop even if the endothermic reaction is the main component. Even if the steam reforming reaction SR proceeds, the combustion reaction continues in the combustion section 18.

_{C m H n + m H 2} O → m CO + (n / 2 + m) H 2 (2)

  As described above, the temperature in the power generation chamber 16 is gradually increased by switching the reforming process in accordance with the progress of the combustion process from the ignition process. When the temperature in the power generation chamber 16 and the fuel cell 4 reaches a predetermined power generation temperature lower than the rated temperature at which the fuel cell module FC is stably operated, the circuit including the fuel cell module FC is closed. Thereby, the fuel cell module FC starts power generation, and a current flows through the circuit (cell operation process). Due to the power generation of the fuel cell, the fuel cell 4 itself also generates heat, and the temperature of the fuel cell 4 rises. As a result, the temperature reaches a rated temperature at which the fuel cell module FC is operated, for example, 600 to 800 ° C.

Thereafter, in order to maintain the rated temperature, a larger amount of fuel gas and air than the amount of fuel gas and air consumed by the fuel cells 4 are supplied, and combustion in the power generation chamber 16 is continued (combustion process). . During power generation, power generation proceeds with a steam reforming reaction SR with high reforming efficiency. The steam reforming reaction SR itself (strictly speaking) is performed at about 400 ° C. to 800 ° C., but is operated at about 500 ° C. to 700 ° C. in combination with a fuel cell.

  As described above, in the present embodiment, when the control unit SC detects that the reformer 5 has a temperature capable of steam reforming by the detection unit TD, The city gas (fuel gas not containing air) and steam are controlled to be supplied, and the reformer 5 performs the steam reforming reaction SR. Since the steam reforming reaction SR is an endothermic reaction, the heat of the combustion section 18 is taken away. However, since the reformer 5 is disposed outside the fuel cells located at the ends of the plurality of fuel cells 4 in the fuel cell assembly 401, the plurality of fuel cells 4 in the combustion unit 18. It is hard to take heat at the edge of the. For this reason, it can suppress that the combustion state in the edge part of the some fuel cell 4 in the combustion part 18 becomes unstable. In the central portion of the combustion unit 18 in the arrangement direction of the plurality of fuel cells 4, heat is taken away by the reformer 5, but the temperature is originally high and the combustion state is good, so the combustion state is not good. There is no fear of becoming stable. As a result, the stability of the combustion state in the combustion section 18 is improved.

  Furthermore, in the present embodiment, the reforming catalyst on the upstream side of the reformer is close to the side wall of the power generation chamber. Therefore, the heat required for the reforming reaction is sufficiently transferred to the reformer when the heat of the combustion section approaches the side wall by convection, and an appropriate reforming reaction is performed.

  In the present embodiment, the pipe 6B is disposed in the projection region of the reformer 5 on the fuel cell 4 side, so that the pipe 6B is disposed closer to the fuel cell 4 and thus the combustion unit 18. It will be. Thereby, the piping 6B receives and heats the heat of the combustion part 18, and can use the heat of the combustion part 18 effectively.

  In the present embodiment, in the fuel cell assembly 401, a plurality of fuel cells 4 are arranged in a matrix. Thereby, it is possible to easily design and manage the configuration in which the reformer 5 is arranged on the inner side of the end portions in the arrangement direction of the plurality of fuel cells 4 in the fuel cell assembly 401.

  In the present embodiment, regarding the arrangement of the fuel cells 4, the number of columns and rows is not limited to the number of the above-described embodiments. For example, as shown in FIG. 8, the number of columns and the number of rows may be the same. In the example shown in FIG. 8, the fuel cells 4 are arranged in 6 rows × 6 columns.

  In the present embodiment, the reformers 5 are arranged so that at least one column of the fuel cells 4 positioned at both ends in the row direction is exposed among the fuel cells 4 arranged in a matrix, Not limited to this. For example, as shown in FIG. 9, among the fuel cells 4 arranged in a matrix, the reformer 5 is arranged so that at least one row of fuel cells 4 positioned at both ends in the column direction is exposed. It may be. In the example shown in FIG. 9, the fuel cells 4 are arranged in 3 rows × 6 columns. Note that the number of exposed columns or rows of the fuel cells 4 depends on the width of the reformer 5 in the row direction.

  Of the fuel cells 4 arranged in a matrix, the reformer 5 may be arranged so that at least one column of fuel cells 4 located at one end in the row direction or the column direction is exposed. .

  The number of reformers 5 is not limited to one and may be two or more. The plurality of reformers 5 can be provided in the row direction or the column direction of the fuel cells 4, for example.

It is a front view which shows the fuel cell module which concerns on this embodiment. It is a perspective view of the fuel cell module which removes and shows a cover member. It is a figure for demonstrating a fuel cell unit. It is a figure for demonstrating a fuel cell stack. It is a schematic diagram for demonstrating the positional relationship of a reformer and a fuel cell assembly. It is a block diagram which shows the structure of the fuel cell which concerns on this embodiment. It is a figure for demonstrating the operation | movement and the operating method of the fuel cell which concern on this embodiment. It is a schematic diagram for demonstrating the modification of the fuel cell module which concerns on this embodiment. It is a schematic diagram for demonstrating the modification of the fuel cell module which concerns on this embodiment.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 3 ... Gas tank, 4 ... Fuel cell, 5 ... Reformer, 6A, 6B ... Piping, 8 ... Fuel gas supply pipe, 10 ... Air supply pipe, 11 ... Exhaust gas pipe, 16 ... Power generation chamber, 18 ... Combustion part , 19 ... Ignition device, 30 ... Fuel cell unit, 400 ... Fuel cell stack, 401 ... Fuel cell assembly, AP ... Air supply unit, CS ... Control unit, EP ... Power extraction unit, FC ... Fuel cell module , FCS ... fuel cell, FP ... fuel supply unit, SC ... control unit, TD ... detection unit, WP ... water supply unit.

Claims (5)

A plurality of fuel cells constituting a fuel cell assembly, wherein a fuel gas channel is disposed inside and the remaining fuel gas is discharged from an outlet of the fuel gas channel;
A reformer unit for a fuel cell, which is disposed above the fuel cell assembly and includes at least one reformer including a reforming catalyst that reforms the gas to be reformed into fuel gas. A fuel cell module for
The reformer is configured to supply only the gas to be reformed and steam when it is detected that the temperature is capable of steam reforming,
On the upper part of the plurality of fuel cells, a combustion part is formed in which the remaining fuel gas that did not contribute to the power generation reaction and the remaining oxidant gas are mixed and burned,
The reforming catalyst on the upstream side of the reformer is disposed outside the fuel cells located at the ends of the plurality of fuel cells in the fuel cell assembly,
The fuel cell module, wherein the reforming catalyst on the upstream side of the reformer is close to a side wall of the power generation chamber. A reformed gas supply pipe for supplying the reformed gas to be reformed by the reformer to the reformer;
2. The fuel cell module according to claim 1, wherein the reformed gas supply pipe is disposed in a projection region of the reformer toward the plurality of fuel cells. 3.   The fuel cell module according to claim 1 or 2, wherein the amount of the reforming catalyst in the reformer is inclined from the upstream side toward the downstream side.   3. The fuel cell module according to claim 1, wherein the reforming catalyst is intermittently filled in the reformer from the upstream side toward the downstream side. 4.   5. The fuel cell module according to claim 1, wherein the plurality of fuel cells are arranged in a matrix in the fuel cell assembly. 6.

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