JP2013157215A - Fuel cell module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable enhancement of thermal efficiency and thermal independence with a simple and compact configuration.SOLUTION: A fuel cell module 12 includes: a first region R1 in which an exhaust gas combustor 52 and a start-up combustor 54 are constituted; a second region R2 in which a heat exchanger 50 is constituted and which circularly rotates around the first region R1; a third region R3 in which a reformer 46 is constituted and which circularly rotates around the second region R2; and a fourth region R4 in which an evaporator 48 is constituted and which circularly rotates around the third region R3. The reformer 46 and the heat exchanger 50 are compared for the magnitude of respective requested heat amount, and then, the heat exchanger 50 having larger requested heating amount is placed in the second region R2 while the reformer 46 having smaller requested heating amount is placed in the third region R3.

Description

  The present invention relates to a fuel cell module including a fuel cell stack in which a plurality of fuel cells that generate power by an electrochemical reaction between a fuel gas and an oxidant gas are stacked.

  In general, a solid oxide fuel cell (SOFC) uses an oxide ion conductor, for example, stabilized zirconia, as a solid electrolyte, and an electrolyte / electrode in which an anode electrode and a cathode electrode are disposed on both sides of the solid electrolyte. A joined body (hereinafter also referred to as MEA) is sandwiched between separators (bipolar plates). This fuel cell is normally used as a fuel cell stack in which a predetermined number of electrolyte / electrode assemblies and separators are laminated.

  As a system incorporating this type of fuel cell stack, for example, a fuel cell battery disclosed in Patent Document 1 is known. As shown in FIG. 8, the fuel cell battery includes a fuel cell stack 1a, and a heat insulating sleeve 2a is attached to one end of the fuel cell stack 1a. Inside the heat insulating sleeve 2a, a heat exchanging device 3a is incorporated and arranged in the reaction device 4a.

  In the reactor 4a, reforming by partial oxidation without using water is performed as a treatment of the liquid fuel. After the liquid fuel is evaporated by the exhaust gas, the liquid fuel passes through the feed position 5a which is a part of the heat exchange device 3a. At that time, the fuel is supplied to the fuel cell stack 1a after being reformed by partial oxidation by contacting the oxygen carrier gas heated by the exhaust gas.

  Moreover, as shown in FIG. 9, the solid oxide fuel cell disclosed in Patent Document 2 includes a battery core 1b and a heat exchanger 2b. The heat exchanger 2b raises the temperature of the cathode air by exhaust heat.

  Further, as shown in FIG. 10, the fuel cell system disclosed in Patent Document 3 includes a vertical columnar first region 1c, an annular second region 2c on the outer peripheral side, and an annular third region on the outer peripheral side. 3c has an annular fourth region 4c on the outer peripheral side thereof.

  A burner 5c is provided in the first region 1c, and a reforming pipe 6c is provided in the second region 2c. The third region 3c is provided with a water evaporator 7c, and the fourth region 4c is provided with a CO transformer 8c.

JP 2001-236980 A Special table 2010-504607 JP 2004-288434 A

  By the way, in Patent Document 1 described above, when reforming by partial oxidation is performed in the reactor 4a, the heat of the exhaust gas is used to heat the liquid fuel and the oxygen carrier gas. Therefore, there is a problem that the amount of heat for raising the temperature of the oxidant gas supplied to the fuel cell stack 1a is likely to be insufficient, and heat self-sustainment is not effectively performed.

  Moreover, in said patent document 2, waste heat is used for temperature rising of the cathode air supplied to the battery core 1b. For this reason, the amount of heat necessary for reforming and raising the temperature of the fuel gas supplied to the battery core 1b is likely to be insufficient. As a result, there is a problem that reforming and heat self-supporting are not performed well.

  Furthermore, in said patent document 3, the heat | fever of the combustion gas from the burner 5c is used for the reforming | reformation of a fuel. Therefore, there is a possibility that the temperature of the oxidant gas supplied to the fuel cell is insufficiently raised, and there is a problem that the heat self-sustainment is not performed effectively.

  The present invention solves this type of problem, and an object thereof is to provide a fuel cell module capable of promoting thermal efficiency and thermal independence with a simple and compact configuration.

  The present invention reforms a fuel cell stack in which a plurality of fuel cells that generate electric power by an electrochemical reaction between a fuel gas and an oxidant gas, and a mixed gas of raw fuel and steam mainly composed of hydrocarbons, The oxidant gas is raised by heat exchange with a reformer that generates the fuel gas supplied to the battery stack, an evaporator that evaporates water and supplies the water vapor to the reformer, and a combustion gas. A heat exchanger for supplying the oxidant gas to the fuel cell stack, and burning the fuel exhaust gas as the fuel gas and the oxidant exhaust gas as the oxidant gas discharged from the fuel cell stack. The present invention relates to a fuel cell module comprising an exhaust gas combustor that generates the combustion gas, and an activation combustor that generates the combustion gas by burning the raw fuel and the oxidant gas. It is intended.

  In this fuel cell module, the first region in which the exhaust gas combustor and the start-up combustor are configured, and one of the reformer and the heat exchanger is configured, and the second region in which the first region is circularly circulated And the other of the reformer or the heat exchanger is configured, the third region that circulates around the second region annularly, and the evaporator is configured, and circulates around the third region annularly And a fourth region.

  Then, the reformer and the heat exchanger are compared with each other in magnitude of required heat quantity, and one having a large required heat quantity is arranged in the second area, and the other having a small required heat quantity is arranged in the third area. Has been.

  Further, in this fuel cell module, the reformer and the heat exchanger are compared with each other in the amount of work per unit temperature. The other having the amount is preferably arranged in the third region.

  For this reason, the arrangement of the reformer and the heat exchanger is set based on the amount of work per unit temperature in the operating conditions and the like. Therefore, the device having a large work amount is arranged closer to the first region where the exhaust gas combustor and the start-up combustor are configured than the device having a small work amount. As a result, the heat balance is optimized and the heat self-sustainment is reliably promoted. Here, the heat self-sustained means that the operating temperature of the fuel cell is maintained only by the heat generated by itself without applying heat from the outside.

  In the fuel cell module, preferably, the reformer includes an annular mixed gas supply chamber to which a mixed gas is supplied, an annular reformed gas discharge chamber to which the generated fuel gas is discharged, and one end of the mixing device. A plurality of reforming conduits communicating with the gas supply chamber and having the other end communicating with the reformed gas discharge chamber, and a combustion gas passage for supplying combustion gas between the reforming conduits are provided.

  The evaporator includes an annular water supply chamber to which water is supplied, an annular water vapor discharge chamber from which water vapor is discharged, and a plurality of evaporators having one end communicating with the water supply chamber and the other end communicating with the water vapor discharge chamber. A combustion gas passage for supplying combustion gas between the pipe and the evaporation pipe is provided.

  The heat exchanger includes an annular oxidant gas supply chamber to which an oxidant gas is supplied, an annular oxidant gas discharge chamber from which the heated oxidant gas is discharged, and one end communicating with the oxidant gas supply chamber. And the other end includes a plurality of heat exchange pipes communicating with the oxidant gas discharge chamber, and a combustion gas passage for supplying combustion gas between the heat exchange pipes.

  As described above, the basic structure of the annular supply chamber, the annular discharge chamber, and the plurality of pipelines facilitates simplification of the structure. Therefore, the manufacturing cost is effectively reduced. In addition, by changing the volume of the supply chamber and the discharge chamber, the pipe length, the pipe diameter, and the number of pipes, it is possible to cope with a wide range of operating conditions and to improve the degree of design freedom.

  Further, in this fuel cell module, the reformed gas discharge chamber, the water vapor discharge chamber, and the oxidant gas discharge chamber are provided on one end side close to the fuel cell stack, while the mixed gas supply chamber, the water supply chamber, The oxidant gas supply chamber is preferably provided on the other end side opposite to the fuel cell stack.

  As a result, the reaction gas immediately after the temperature rise and reforming can be quickly supplied to the fuel cell stack. On the other hand, the exhaust gas from the fuel cell stack can be supplied to the exhaust gas combustor, reformer, heat exchanger, and evaporator constituting the FC peripheral equipment while minimizing the temperature drop due to heat radiation, and the thermal efficiency is high. It improves and promotes heat independence.

  Furthermore, in this fuel cell module, after the combustion gas flows in the order of the combustion gas passage in the first region, the combustion gas passage in the second region, the combustion gas passage in the third region, and the combustion gas passage in the fourth region, It is preferable that the fuel cell module is discharged to the outside. For this reason, it becomes possible to effectively supply heat to the exhaust gas combustor, the reformer, the heat exchanger, and the evaporator constituting the FC peripheral device, thereby improving the thermal efficiency and promoting the heat independence.

  In this fuel cell module, it is preferable that at least one of the evaporation pipes constitutes an evaporation return pipe that communicates the water vapor discharge chamber and the mixed gas supply chamber. Accordingly, the steam is mixed with the raw fuel in the mixed gas supply chamber of the reformer while maintaining a high temperature to obtain a mixed gas. Thereby, improvement of reforming efficiency is achieved.

  Furthermore, in this fuel cell module, the fuel cell module is preferably a solid oxide fuel cell module. For this reason, it is particularly suitable for high-temperature fuel cells such as SOFC.

  According to the present invention, the annular second region, the third region, and the fourth region are sequentially provided outward, respectively, centering on the first region in which the exhaust gas combustor and the start-up combustor are configured. It has been. For this reason, it is possible to set a device having a high temperature and a small heat demand on the inside, while setting a device having a low temperature and a small heat demand to the outside. Therefore, the thermal efficiency is improved, the heat self-sustainment is promoted, and the simple and compact configuration can be realized.

  Moreover, the arrangement of the reformer and the heat exchanger is set based on the amount of required heat. That is, on the basis of the required heat quantity in the operating condition or the like, the equipment having a large required heat quantity is arranged closer to the first region where the exhaust gas combustor and the start-up combustor are configured than the equipment having a small required heat quantity. As a result, the heat balance is optimized and the heat self-sustainment is reliably promoted.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a schematic configuration explanatory diagram of a fuel cell system in which a fuel cell module according to a first embodiment of the present invention is incorporated. FIG. 2 is a partially omitted perspective explanatory view of FC peripheral devices constituting the fuel cell module. It is a principal part disassembled perspective explanatory drawing of the said FC peripheral device. It is a principal part expansion perspective explanatory drawing of the said FC peripheral device. It is explanatory drawing of the piping arrangement | sequence state of the said fuel cell module. It is schematic structure explanatory drawing of the fuel cell system in which the fuel cell module which concerns on the 2nd Embodiment of this invention is integrated. FIG. 2 is a partially omitted perspective explanatory view of FC peripheral devices constituting the fuel cell module. 1 is a schematic explanatory diagram of a fuel cell battery disclosed in Patent Document 1. FIG. FIG. 5 is a partially cutaway perspective view of a solid oxide fuel cell disclosed in Patent Document 2. It is a schematic explanatory drawing of the fuel cell system currently disclosed by patent document 3. FIG.

  As shown in FIG. 1, the fuel cell system 10 incorporates the fuel cell module 12 according to the first embodiment of the present invention, and is used for various uses such as in-vehicle use as well as stationary use.

  The fuel cell system 10 includes a fuel cell module (SOFC module) 12 that generates power by an electrochemical reaction between a fuel gas (a gas in which methane and carbon monoxide are mixed in hydrogen gas) and an oxidant gas (air), and the fuel cell. A raw fuel supply device (including a fuel gas pump) 14 for supplying raw fuel (for example, city gas) to the module 12 and an oxidant gas supply device (including an air pump) for supplying the oxidant gas to the fuel cell module 12 ) 16, a water supply device (including a water pump) 18 that supplies water to the fuel cell module 12, and a control device 20 that controls the power generation amount of the fuel cell module 12.

  The fuel cell module 12 includes a solid oxide fuel cell stack 24 in which a plurality of solid oxide fuel cells 22 are stacked in the vertical direction (or horizontal direction). The fuel cell 22 includes, for example, an electrolyte / electrode assembly (MEA) 32 in which a cathode electrode 28 and an anode electrode 30 are provided on both surfaces of an electrolyte 26 made of an oxide ion conductor such as stabilized zirconia.

  On both sides of the electrolyte / electrode assembly 32, a cathode side separator 34 and an anode side separator 36 are disposed. The cathode side separator 34 is formed with an oxidant gas flow path 38 for supplying an oxidant gas to the cathode electrode 28, and the anode side separator 36 is supplied with a fuel gas flow path 40 for supplying fuel gas to the anode electrode 30. Is formed. As the fuel cell 22, various SOFCs conventionally used can be used.

  The operating temperature of the fuel cell 22 is as high as several hundred degrees Celsius. In the anode electrode 30, methane in the fuel gas is reformed to obtain hydrogen and CO. The hydrogen and CO are the anode electrode 30 of the electrolyte 26. Supplied to the side.

  In the fuel cell stack 24, an oxidant gas inlet communication hole 42 a that communicates integrally with the inlet side of each oxidant gas flow path 38, and an oxidant gas outlet communication that communicates integrally with the outlet side of the oxidant gas flow path 38. A hole 42b, a fuel gas inlet communication hole 44a that communicates integrally with the inlet side of each fuel gas flow path 40, and a fuel gas outlet communication hole 44b that communicates integrally with the outlet side of the fuel gas flow path 40 are provided.

  The fuel cell module 12 reforms a mixed gas of raw fuel (for example, city gas) mainly composed of hydrocarbons and water vapor, and generates a fuel gas to be supplied to the fuel cell stack 24. While evaporating water, the evaporator 48 that supplies the water vapor to the reformer 46 and the temperature of the oxidant gas are increased by heat exchange with the combustion gas, and the oxidant gas is supplied to the fuel cell stack 24. A heat exchanger 50, an exhaust gas combustor 52 that burns fuel exhaust gas that is the fuel gas discharged from the fuel cell stack 24 and oxidant exhaust gas that is the oxidant gas, and generates the combustion gas; A starting combustor that burns the raw fuel and the oxidant gas to generate the combustion gas.

  The fuel cell module 12 basically includes a fuel cell stack 24 and an FC peripheral device 56. The FC peripheral device 56 includes a reformer 46, an evaporator 48, a heat exchanger 50, an exhaust gas combustor 52, and a start-up combustor 54.

  As shown in FIG. 2, the FC peripheral device 56 includes an exhaust gas combustor 52 and a start-up combustor 54, for example, a first region R1 having a circular shape with an opening, and a heat exchanger 50, The reformer 46 is configured with a second region R2 that circulates around the first region R1, and a vaporizer 48 is configured with a third region R3 that circulates around the second region R2 annularly. And a fourth region R4 that circulates around the third region R3 annularly. A cylindrical outer peripheral member 55 constituting the outer wall is disposed on the outer periphery of the fourth region R4 (see FIG. 2).

The reformer 46 and the heat exchanger 50 compare the magnitudes of the respective required heat amounts, and one having a large required heat amount is disposed in the second region R2 and the other having a small required heat amount is the third. Arranged in region R3. The required heat quantity (J) is the amount of work per unit temperature (J · K ^-1 ), flow rate (mol), specific heat (J · mol ^-1 · K ^-1 ) and temperature (stop temperature, for example, room temperature and each device) The temperature difference from the rated temperature of (K). That is, required heat amount = work amount per unit temperature (= flow rate × specific heat) × temperature.

Specifically, the amount of heat required to raise the temperature of the reforming catalyst (a pellet catalyst 84 described later) from the normal temperature to the reforming catalyst reaction temperature range (varies depending on the amount of catalyst, catalyst type, and reforming catalyst reaction temperature range). ) _Qref0 , the amount of heat required for the reforming reaction (endothermic reaction) of the reforming catalyst (which varies depending on the amount of catalyst, the type of catalyst and the reforming catalyst reaction temperature range) _Qref1 , and the amount of heat necessary for raising the temperature of the fuel ( Q _fuel is the fuel flow rate and the reforming catalyst reaction temperature range), and Q _air is the amount of heat required to raise the temperature of the theoretical A / F (air / fuel gas) (varies depending on the stack rated temperature range). .

In the first embodiment, a relationship of Q _ref0 + Q _ref1 + Q _fuel <Q _air is obtained. That is, the required heat amount of the heat exchanger 50 is larger than the required heat amount of the reformer 46, and the heat exchanger 50 is disposed in the second region R2, while the reformer 46 is disposed in the third region R3. Be placed.

  Here, the reformer 46 and the heat exchanger 50 compare the amount of work per unit temperature, and one having a large work amount is disposed in the second region R2 and has a small work amount. You may set so that the other to have may be arrange | positioned in 3rd area | region R3.

  As shown in FIGS. 2 and 3, the start-up combustor 54 includes an air supply pipe 57 and a raw fuel supply pipe 58. The start-up combustor 54 has an ejector function, and sucks the raw fuel by generating a negative pressure in the raw fuel supply pipe 58 by the air flow introduced from the air supply pipe 57.

  The exhaust gas combustor 52 includes a cylindrical member 60 that houses the start-up combustor 54. A plurality of holes 62 are formed on the peripheral surface of the cylindrical member 60 (see FIGS. 2 to 4). In the cylindrical member 60, one end of the oxidant exhaust gas passage 63a and one end of the fuel exhaust gas passage 63b are disposed. In the cylindrical member 60, combustion gas is generated by a combustion reaction between fuel gas (specifically, fuel exhaust gas) and oxidant gas (specifically, oxidant exhaust gas).

  As shown in FIG. 1, the other end of the oxidant exhaust gas passage 63 a is connected to the oxidant gas outlet communication hole 42 b of the fuel cell stack 24, and the other end of the fuel exhaust gas passage 63 b is connected to the fuel cell stack 24. It is connected to the fuel gas outlet communication hole 44b. As shown in FIGS. 2 and 3, the heat exchanger 50 includes a plurality of heat exchange pipes (heat transfer pipes) 64 disposed on the outer periphery of the cylindrical member 60. One end of the heat exchange pipe 64 (the other end opposite to the fuel cell stack 24, the same applies hereinafter) is fixed to the first inner ring 66a and the other end of the heat exchange pipe 64 ( One end on the fuel cell stack 24 side (hereinafter the same) is fixed to the first inner ring 66b. First outer rings 68a and 68b are disposed outside the first inner rings 66a and 66b.

  An annular oxidant gas supply chamber 70a to which an oxidant gas is supplied is formed between the first inner ring 66a and the first outer ring 68a. Between the first inner ring 66b and the first outer ring 68b, an annular oxidant gas discharge chamber 70b from which the heated oxidant gas is discharged is formed (see FIGS. 2 to 4). Both ends of the heat exchange pipe 64 are opened to an oxidant gas supply chamber 70a and an oxidant gas discharge chamber 70b.

  An oxidant gas supply pipe 72 is disposed in the oxidant gas supply chamber 70a. One end of the oxidant gas passage 74 is disposed in the oxidant gas discharge chamber 70b, and the other end of the oxidant gas passage 74 is connected to the oxidant gas inlet communication hole 42a of the fuel cell stack 24. (See FIG. 1).

The reformer 46 converts higher hydrocarbons (C ₂₊ ) such as ethane (C ₂ H ₆ ), propane (C ₃ H ₈ ) and butane (C ₄ H ₁₀ ) contained in city gas (raw fuel), This is a pre-reformer for steam reforming to a fuel gas mainly containing methane (CH ₄ ), hydrogen, and CO, and is set at an operating temperature of several hundred degrees Celsius.

  As shown in FIGS. 2 and 3, the reformer 46 includes a plurality of reforming pipes (heat transfer pipes) 76 disposed on the outer periphery of the heat exchanger 50. One end of the reforming conduit 76 is fixed to the second inner ring 78a, and the other end of the reforming conduit 76 is fixed to the second inner ring 78b. Second outer rings 80a and 80b are disposed outside the second inner rings 78a and 78b.

  An annular mixed gas supply chamber 82a to which a mixed gas (raw fuel and water vapor) is supplied is formed between the second inner ring 78a and the second outer ring 80a. Between the second inner ring 78b and the second outer ring 80b, an annular reformed gas discharge chamber 82b for discharging the generated fuel gas (reformed gas) is formed.

  Both ends of the reforming conduit 76 are opened to a mixed gas supply chamber 82a and a reformed gas discharge chamber 82b. Each reforming line 76 is filled with a reforming pellet catalyst 84. At both ends of the reforming pipe 76, a wire net 86 for holding the pellet catalyst 84 is disposed. A raw fuel supply path 88 is connected to the mixed gas supply chamber 82 a, and an evaporation return pipe 102 to be described later is connected to the raw fuel supply path 88. One end of the fuel gas passage 90 communicates with the reformed gas discharge chamber 82b, and the other end of the fuel gas passage 90 communicates with the fuel gas inlet communication hole 44a of the fuel cell stack 24 (see FIG. 1).

  The evaporator 48 includes a plurality of evaporation pipes (heat transfer pipes) 92 disposed on the outer periphery of the reformer 46. One end of the evaporation pipe 92 is fixed to the third inner ring 94a, and the other end of the evaporation pipe 92 is fixed to the third inner ring 94b. Third outer rings 96a and 96b are disposed outside the third inner rings 94a and 94b.

  An annular water supply chamber 98a for supplying water is formed between the third inner ring 94a and the third outer ring 96a. Between the third inner ring 94b and the third outer ring 96b, an annular water vapor discharge chamber 98b from which water vapor is discharged is formed. Both ends of the evaporation pipe line 92 are opened to a water supply chamber 98a and a water vapor discharge chamber 98b.

  A water passage 100 is disposed in the water supply chamber 98a. In the water vapor discharge chamber 98b, one end of an evaporation return line 102 constituted by at least one evaporation line 92 is disposed, and the other end of the evaporation return line 102 is connected to a raw fuel supply line 88. (See FIG. 1). The raw fuel supply path 88 has an ejector function, and generates negative pressure by the raw fuel to be circulated to suck water vapor.

  As shown in FIG. 1, the raw fuel supply device 14 includes a raw fuel passage 104. The raw fuel passage 104 branches into a raw fuel supply path 88 and a raw fuel supply pipe 58 via a raw fuel adjustment valve 106. A desulfurizer 108 for removing sulfur compounds contained in the city gas (raw fuel) is disposed in the raw fuel supply path 88.

  The oxidant gas supply device 16 includes an oxidant gas passage 110. The oxidant gas passage 110 branches into an oxidant gas supply pipe 72 and an air supply pipe 57 via an oxidant gas adjustment valve 112. The water supply device 18 is connected to the evaporator 48 through the water passage 100.

  In the first embodiment, as shown in FIG. 5, an imaginary line L1 connecting the center O of the first region R1 and the conduit center O2 of each reforming conduit 76 in the third region R3 is set. Between each virtual line L1, the pipe center O1 of each heat exchange pipe 64 in the second region R2 and the pipe center O3 of each evaporation pipe 92 in the fourth region R4 are arranged. In other words, the pipe center O1 of each heat exchange pipe 64 and the pipe center O3 of each evaporation pipe 92 are arranged at positions separated from each virtual line L1. A part of each heat exchange pipe 64 or a part of each evaporation pipe 92 may be disposed on each virtual line L1.

In the first embodiment, two virtual lines L0 _end extending radially from the center O of the first region R1 are set. Each imaginary line L0 _end is in contact with the outer periphery of each pipe and forms a maximum angle with each other. In FIG. 5, the position in contact with the outer circumference of the reforming pipes 76 on both sides is defined as the outer restriction position. When an arbitrary virtual line L0 extending radially from the center O of the first region R1 is set within the range of the outer regulation position, at least the heat exchange pipe 64 of the second region R2 is placed on the virtual line L0. A part of the reforming conduit 76 in the third region R3 or the evaporation conduit 92 in the fourth region R4 is disposed. When the heat exchange pipes 64, the reforming pipes 76, and the evaporation pipes 92 are arranged around the center O of the first region R1 (first embodiment), There is no virtual line L0 _{end serving as the} outer regulation position, and a virtual line L0 extending radially from the center O in all directions is set.

  A first combustion gas passage 116a through which combustion gas flows is formed in the first region R1, a second combustion gas passage 116b through which the combustion gas flows is formed in the second region R2, and a third region R3 is formed in the third region R3. A third combustion gas passage 116c through which the combustion gas flows is formed, and a fourth combustion gas passage 116d through which the combustion gas flows is formed in the fourth region R4.

  The operation of the fuel cell system 10 configured as described above will be described below.

  When the fuel cell system 10 is activated, air (oxidant gas) and raw fuel are supplied to the activation combustor 54. Specifically, in the oxidant gas supply device 16, air is supplied to the oxidant gas passage 110 under the driving action of the air pump. This air is supplied to the air supply pipe 57 under the opening degree adjusting action of the oxidant gas adjustment valve 112.

On the other hand, in the raw fuel supply device 14, raw gas such as city gas (including CH ₄ , C ₂ H ₆ , C ₃ H ₈ , and C ₄ H ₁₀ ) is supplied to the raw fuel passage 104 under the operation of the fuel gas pump. Fuel is supplied. The raw fuel is introduced into the raw fuel supply pipe 58 under the opening adjustment operation of the raw fuel adjustment valve 106. The raw fuel is mixed with air and supplied into the start-up combustor 54 (see FIG. 2).

  For this reason, a mixed gas of raw fuel and air is supplied into the start-up combustor 54, and combustion is started when this mixed gas is ignited. Accordingly, in the exhaust gas combustor 52 that is directly connected to the start-up combustor 54, the combustion gas is supplied from the start-up combustor 54 to the cylindrical member 60.

  A plurality of holes 62 are formed in the cylindrical member 60. Thereby, the combustion gas supplied into the cylindrical member 60 passes through the plurality of holes 62 and is introduced from the first region R1 to the second region R2. The combustion gas is further supplied to the third region R3, then introduced into the fourth region R4, and discharged to the outside of the fuel cell module 12.

  At that time, the heat exchanger 50 is disposed in the second region R2, the reformer 46 is disposed in the third region R3, and the evaporator 48 is disposed in the fourth region R4. ing. Therefore, the combustion gas discharged from the first region R1 is heated in the order of the heat exchanger 50, the reformer 46, and the evaporator 48.

  When the fuel cell module 12 is heated to a set temperature, an oxidant gas is supplied to the heat exchanger 50, while a gas mixture of raw fuel and water vapor is supplied to the reformer 46.

  Specifically, the opening degree of the oxidant gas adjustment valve 112 is adjusted, the amount of air supplied to the oxidant gas supply pipe 72 is increased, and the opening degree of the raw fuel adjustment valve 106 is adjusted. The amount of raw fuel supplied to the raw fuel supply path 88 is increased. Further, water is supplied to the water passage 100 under the action of the water supply device 18.

  Therefore, as shown in FIGS. 2 and 3, the air introduced into the heat exchanger 50 is temporarily supplied to the oxidant gas supply chamber 70 a and then moves in the plurality of heat exchange pipes 64. Heated (heat exchanged) by the combustion gas introduced into the second region R2. The heated air is once supplied to the oxidant gas discharge chamber 70b and then supplied to the oxidant gas inlet communication hole 42a of the fuel cell stack 24 through the oxidant gas passage 74 (see FIG. 1).

  In the fuel cell stack 24, the heated air flows through the oxidant gas flow path 38 and is then discharged from the oxidant gas outlet communication hole 42 b to the oxidant exhaust gas passage 63 a. The oxidant exhaust gas passage 63 a is open to the cylindrical member 60 constituting the exhaust gas combustor 52, and the oxidant exhaust gas is introduced into the cylindrical member 60.

  Further, as shown in FIG. 1, the water supplied from the water supply device 18 is supplied to the evaporator 48, and the raw fuel desulfurized by the desulfurizer 108 is circulated through the raw fuel supply path 88 to be modified. Head to the psalm 46.

  In the evaporator 48, after the water is once supplied to the water supply chamber 98a, the temperature is raised by the combustion gas flowing through the fourth region R4 and steamed while moving in the plurality of evaporation pipes 92. . The water vapor is once introduced into the water vapor discharge chamber 98b, and then supplied to the evaporation return pipe 102 communicating with the water vapor discharge chamber 98b. As a result, the water vapor flows through the evaporation return pipe 102 and is introduced into the raw fuel supply path 88, and is mixed with the raw fuel to obtain a mixed gas.

The mixed gas is temporarily supplied from the raw fuel supply path 88 to the mixed gas supply chamber 82 a constituting the reformer 46. The mixed gas moves in the plurality of reforming pipes 76. In the meantime, the mixed gas is heated by the combustion gas flowing through the third region R3 and steam reformed through the pellet catalyst 84 to remove (reform) C ₂₊ hydrocarbons to mainly produce methane. A reformed gas as a component is obtained.

  The reformed gas is once supplied to the reformed gas discharge chamber 82b as heated fuel gas, and then supplied to the fuel gas inlet communication hole 44a of the fuel cell stack 24 through the fuel gas passage 90 (FIG. 1).

  In the fuel cell stack 24, the heated fuel gas flows through the fuel gas passage 40 and is then discharged from the fuel gas outlet communication hole 44 b to the fuel exhaust gas passage 63 b. The fuel exhaust gas passage 63 b is opened in the cylindrical member 60 constituting the exhaust gas combustor 52, and the fuel exhaust gas is introduced into the cylindrical member 60.

  Note that, when the inside of the exhaust gas combustor 52 exceeds the self-ignition temperature of the fuel gas under the temperature rising action by the start-up combustor 54, combustion by the oxidant exhaust gas and the fuel exhaust gas is started in the cylindrical member 60.

  In this case, in the first embodiment, the FC peripheral device 56 includes the first region R1 in which the exhaust gas combustor 52 and the start-up combustor 54 are configured, the heat exchanger 50, and the first region. The second region R2 that circulates around R1 and the reformer 46 are configured, the third region R3 that circulates around the second region R2 and the evaporator 48, and the third region R3. And a fourth region R4 that circulates around the region R3 in a ring shape.

  That is, the second region R2, the third region R3, and the fourth region R4 each having an annular shape are sequentially provided outward from the first region R1. For this reason, equipment with high temperature and heat demand, for example, the heat exchanger 50 (and the reformer 46) is installed on the inside, while equipment with low temperature and low heat demand, for example, the evaporator 48, is set on the outside. Can do.

  For example, the heat exchanger 50 needs a temperature of 550 ° C. to 650 ° C., and the reformer 46 needs a temperature of 550 ° C. to 600 ° C. On the other hand, the evaporator 48 requires a temperature of 150 ° C. to 200 ° C. Therefore, the thermal efficiency is improved, the heat self-sustainment is promoted, and an effect that it is possible to construct a simple and compact structure is obtained.

  Moreover, the reformer 46 and the heat exchanger 50 are compared with each other in magnitude of the required heat quantity, and one having a large required heat quantity is arranged in the second region R2, and the other having a small required heat quantity is the third. Arranged in region R3. In the first embodiment, the required heat amount of the heat exchanger 50 is larger than the required heat amount of the reformer 46, and the heat exchanger 50 is disposed in the second region R2, while the heat exchanger 50 is disposed in the third region R3. A reformer 46 is arranged.

  As a result, in a relatively low A / F (air / fuel gas) environment, the reformer 46 suitable for low-temperature reforming is used well, the heat balance is optimized, and the heat self-sustainment is surely promoted. The effect of being achieved is obtained. Here, the heat self-sustained means that the operating temperature of the fuel cell 22 is maintained only by the heat generated by itself without applying heat from the outside.

  Further, in the first embodiment, the reformer 46 and the heat exchanger 50 are arranged in the second region R2 with one having a larger work amount by comparing the work amounts per unit temperature. The other having a small work amount is arranged in the third region R3.

  In the first embodiment, based on the amount of work per unit temperature in the operating conditions, the heat exchanger 50 having a large work amount is activated by the exhaust gas combustor 52 and starting than the reformer 46 having a small work amount. The first combustor 54 is disposed close to the first region R1, that is, in the second region R2. As a result, the heat balance is optimized and the heat self-sustainment is reliably promoted.

  Further, in the first embodiment, as shown in FIG. 2, the reformer 46 includes an annular mixed gas supply chamber 82a to which a mixed gas is supplied, and an annular reformed gas from which the generated fuel gas is discharged. Combustion gas is discharged between the reforming conduits 76, a plurality of reforming conduits 76 having one end communicating with the mixed gas supply chamber 82 a and the other end communicating with the reformed gas discharging chamber 82 b. A third combustion gas passage 116c for supplying is provided.

  2 and 5, the evaporator 48 includes an annular water supply chamber 98a to which water is supplied, an annular water vapor discharge chamber 98b from which water vapor is discharged, one end communicating with the water supply chamber 98a, and The other end includes a plurality of evaporation pipes 92 communicating with the water vapor discharge chamber 98b, and a fourth combustion gas passage 116d for supplying combustion gas between the evaporation pipes 92.

  The heat exchanger 50 includes an annular oxidant gas supply chamber 70a to which an oxidant gas is supplied, an annular oxidant gas discharge chamber 70b to which the heated oxidant gas is discharged, and one end of the oxidant gas supply. A plurality of heat exchange pipes 64 communicating with the chamber 70a and the other end communicating with the oxidant gas discharge chamber 70b; and a second combustion gas passage 116b for supplying combustion gas between the heat exchange pipes 64. ing.

  Thus, an annular supply chamber (mixed gas supply chamber 82a, water supply chamber 98a and oxidant gas supply chamber 70a), an annular discharge chamber (reformed gas discharge chamber 82b, water vapor discharge chamber 98b and oxidant gas discharge chamber). 70b) and a plurality of pipe lines (the reforming pipe line 76, the evaporation pipe line 92, and the heat exchange pipe line 64) have a basic configuration, the structure can be easily simplified. Therefore, the manufacturing cost of the entire fuel cell module 12 is effectively reduced. In addition, by changing the volume of the supply chamber and the discharge chamber, the pipe length, the pipe diameter, and the number of pipes, it is possible to cope with a wide range of operating conditions and to improve the degree of design freedom.

  Furthermore, in the first embodiment, the reformed gas discharge chamber 82b, the water vapor discharge chamber 98b, and the oxidant gas discharge chamber 70b are provided on one end side close to the fuel cell stack 24, and are supplied with mixed gas. The chamber 82a, the water supply chamber 98a, and the oxidant gas supply chamber 70a are provided on the other end side opposite to the fuel cell stack 24.

  As a result, the reaction gas (fuel gas and oxidant gas) immediately after the temperature rise and reforming can be quickly supplied to the fuel cell stack 24. On the other hand, the exhaust gas from the fuel cell stack 24 is supplied to the reformer 46, the evaporator 48, the heat exchanger 50, and the exhaust gas combustor 52 constituting the FC peripheral device 56 while suppressing the temperature drop due to heat radiation to the minimum. It is possible to improve thermal efficiency and promote thermal self-sustainability.

  Further, as shown in FIG. 5, the combustion gas includes the first combustion gas passage 116a in the first region R1, the second combustion gas passage 116b in the second region R2, the third combustion gas passage 116c in the third region R3, and the first combustion gas passage 116c. After flowing through the fourth combustion gas passage 116d in the fourth region R4 in this order, the fuel is discharged outside the fuel cell module 12. For this reason, it becomes possible to effectively supply heat to the exhaust gas combustor 52, the heat exchanger 50, the reformer 46, and the evaporator 48 that constitute the FC peripheral device 56, and the heat efficiency is improved and the heat self-sustained. Promotion is planned.

  Further, in the evaporator 48, at least one of the evaporation pipes 92 constitutes an evaporation return pipe 102 that communicates the water vapor discharge chamber 98b and the mixed gas supply chamber 82a of the reformer 46. Accordingly, the water vapor is mixed with the raw fuel in the mixed gas supply chamber 82a of the reformer 46 while maintaining a high temperature to obtain a mixed gas. Therefore, the reforming efficiency is improved.

  The fuel cell module 12 is a solid oxide fuel cell module. This is particularly suitable for high-temperature fuel cells such as SOFC.

  As shown in FIG. 6, the fuel cell system 130 incorporates a fuel cell module 132 according to the second embodiment of the present invention. Note that the same components as those of the fuel cell module 12 according to the first embodiment are denoted by the same reference numerals, and detailed description thereof is omitted.

  As shown in FIG. 7, the fuel cell module 132 includes the exhaust gas combustor 52 and the start-up combustor 54. For example, the fuel cell module 132 includes a first region R1 having a circular opening shape and a reformer 46. A second region R2 that circulates around the first region R1 and a heat exchanger 50 are configured, and a third region R3 that circulates around the second region R2 and an evaporator 48 are configured. And a fourth region R4 that circulates around the third region R3 annularly.

In the second embodiment, a relationship of Q _ref0 + Q _ref1 + Q _fuel > Q _air is obtained. That is, the required heat amount of the reformer 46 is larger than the required heat amount of the heat exchanger 50, and the reformer 46 is disposed in the second region R2, while the heat exchanger 50 is disposed in the third region R3. Be placed.

  In the second embodiment configured as described above, the fuel cell module 132 includes the first circular region R1 in which the exhaust gas combustor 52 and the start-up combustor 54 are configured, and the reformer 46. In addition, a second region R2 that circulates around the first region R1 and a heat exchanger 50 are configured, and a third region R3 that circulates around the second region R2 and an evaporator 48 And a fourth region R4 that circulates around the third region R3 in a ring shape.

  For this reason, the reformer 46 (and the heat exchanger 50), which is a device having a high temperature and a large heat demand, can be installed inside, while the evaporator 48, a device having a low temperature and a small heat demand, can be set to the outside. .

  Moreover, the required heat amount of the reformer 46 is larger than the required heat amount of the heat exchanger 50, and the reformer 46 is disposed in the second region R2, while the heat exchanger 50 is disposed in the third region R3. Has been placed.

  Accordingly, the same effects as those of the first embodiment can be obtained, such as improvement of thermal efficiency, promotion of heat self-sustainment, and simple and compact configuration. Particularly, since the reformer 46 is disposed inside the heat exchanger 50, the reformer 46 suitable for high-temperature reforming is favorable in an environment where the A / F (air / fuel gas) is relatively high. Used for.

DESCRIPTION OF SYMBOLS 10, 130 ... Fuel cell system 12, 132 ... Fuel cell module 14 ... Raw fuel supply device 16 ... Oxidant gas supply device 18 ... Water supply device 20 ... Control device 22 ... Fuel cell 24 ... Fuel cell stack 26 ... Electrolyte 28 ... Cathode electrode 30 ... Anode electrode 32 ... Electrolyte / electrode assembly 38 ... Oxidant gas passage 40 ... Fuel gas passage 46 ... Reformer 48 ... Evaporator 50 ... Heat exchanger 52 ... Exhaust gas combustor 54 ... Start-up combustion 56 ... FC peripheral device 57 ... Air supply pipe 58 ... Raw fuel supply pipe 60 ... Cylindrical member 62 ... Hole portion 64 ... Heat exchange line 66a, 66b, 78a, 78b, 94a, 94b ... Inner ring 68a, 68b, 80a 80b, 96a, 96b ... outer ring 70a ... oxidant gas supply chamber 70b ... oxidant gas discharge chamber 74 ... oxidant gas passage 82a ... mixed gas supply chamber 8 b ... reformed gas discharge chamber 84 ... pellet-shaped catalyst 88 ... raw fuel supply passage 90 ... fuel gas passage 92 ... evaporation conduit 98a ... water supply chamber 98b ... water vapor discharge chamber 100 ... water passage 102 ... evaporation return conduit 116a- 116d ... Combustion gas passage

Claims (7)

A fuel cell stack in which a plurality of fuel cells that generate electricity by an electrochemical reaction between a fuel gas and an oxidant gas are stacked;
A reformer that reforms a mixed gas of a raw fuel mainly composed of hydrocarbons and water vapor and generates the fuel gas supplied to the fuel cell stack;
An evaporator for evaporating water and supplying the steam to the reformer;
A heat exchanger that raises the temperature of the oxidant gas by heat exchange with a combustion gas and supplies the oxidant gas to the fuel cell stack;
An exhaust gas combustor for burning the fuel exhaust gas as the fuel gas discharged from the fuel cell stack and the oxidant exhaust gas as the oxidant gas to generate the combustion gas;
A starting combustor for burning the raw fuel and the oxidant gas to generate the combustion gas;
A fuel cell module comprising:
A first region in which the exhaust gas combustor and the start-up combustor are configured;
One of the reformer or the heat exchanger is configured, and a second region that circulates around the first region annularly,
The other of the reformer or the heat exchanger is configured, and a third region that circulates around the second region annularly,
The evaporator is configured, and a fourth region that circulates around the third region annularly,
With
The reformer and the heat exchanger are compared with each other in the required heat quantity, one having a large required heat quantity is disposed in the second area, and the other having a small required heat quantity is the third area. A fuel cell module, which is disposed in   2. The fuel cell module according to claim 1, wherein the reformer and the heat exchanger are arranged in the second region, one of which has a large work amount by comparing the amount of work per unit temperature. And the other having a small work amount is disposed in the third region. The fuel cell module according to claim 1 or 2, wherein the reformer includes an annular mixed gas supply chamber to which the mixed gas is supplied, an annular reformed gas discharge chamber to which the generated fuel gas is discharged, A plurality of reforming pipes having one end communicating with the mixed gas supply chamber and the other end communicating with the reformed gas discharge chamber, and a combustion gas passage for supplying the combustion gas between the reforming pipes ,
The evaporator includes an annular water supply chamber to which the water is supplied, an annular water vapor discharge chamber from which the water vapor is discharged, a plurality of one ends communicating with the water supply chamber and the other end communicating with the water vapor discharge chamber. An evaporation line of the book, and a combustion gas passage for supplying the combustion gas between the evaporation lines,
The heat exchanger includes an annular oxidant gas supply chamber to which the oxidant gas is supplied, an annular oxidant gas discharge chamber from which the heated oxidant gas is discharged, and one end of the oxidant gas supply chamber A plurality of heat exchange pipes communicating with each other at the other end and communicating with the oxidant gas discharge chamber, and a fuel gas passage for supplying the combustion gas between the heat exchange pipes module. The fuel cell module according to claim 3, wherein the reformed gas discharge chamber, the water vapor discharge chamber, and the oxidant gas discharge chamber are provided on one end side close to the fuel cell stack,
The fuel cell module, wherein the mixed gas supply chamber, the water supply chamber, and the oxidant gas supply chamber are provided on the other end side opposite to the fuel cell stack.   5. The fuel cell module according to claim 3, wherein the combustion gas includes a combustion gas passage in the first region, the combustion gas passage in the second region, the combustion gas passage in the third region, and the fourth region. After being circulated in the order of the combustion gas passages, the fuel cell module is discharged outside the fuel cell module.   The fuel cell module according to any one of claims 2 to 5, wherein at least one of the evaporation pipes constitutes an evaporation return pipe that communicates the water vapor discharge chamber and the mixed gas supply chamber. A fuel cell module.   The fuel cell module according to any one of claims 1 to 6, wherein the fuel cell module is a solid oxide fuel cell module.

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