JP6550813B2 - Fuel cell module - Google Patents

Description

  The present invention relates to a fuel cell module in which a fuel cell stack is disposed in a heat insulating casing.

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

  Therefore, conventionally, in a fuel cell module provided with such a fuel cell stack, the reformer is heated by a burner at start-up, or a heater is installed in a pipe connected to the fuel cell stack and introduced into the fuel cell stack Fuel and air were heated.

  For example, Patent Document 1 describes a configuration in which a heater is provided in each of the pipes for introducing fuel and air into the fuel cell stack to heat the introduced fuel and air. Patent Document 2 describes a configuration in which air introduced into the fuel cell stack is heated by a heater, and moisture around the cathode is dried and removed. Patent Document 3 describes a configuration in which a thin film heater is provided in the fuel cell stack itself and the fuel cell stack body is heated at the start of power generation.

JP 2008-97891 A JP 2010-251219 A JP 2004-111307 A

  However, the fuel cell module as described above may or may not have a gas burner, depending on the system configuration, and heating by the gas burner is localized heating, so the entire system may be uniformly heated. difficult. The same applies to the case where the fuel cell stack body is heated with a thin film heater as in the configuration of Patent Document 3, and it is difficult to improve the thermal efficiency of the entire system. In the configuration in which the pipe is heated by the heater as in Patent Documents 1 and 2 described above, the heat transfer area is insufficient, and it is difficult to improve the thermal efficiency of the entire system also in this case.

  The present invention has been made in consideration of the above-mentioned conventional problems, and an object thereof is to provide a fuel cell module capable of efficiently preheating reformed fuel or air introduced into a fuel cell stack.

  The fuel cell module according to the present invention is a fuel cell module in which a fuel cell stack is disposed in a heat insulating case, and fuel supplied to the fuel cell stack is modified around the fuel cell stack in the heat insulating case. At least one of a reformer for reforming, a reformed water evaporator for producing reforming steam used for reforming reaction in the reformer, and an air preheater for preheating air supplied to the fuel cell stack Are provided, and heating means is provided on the side of the reformer, the reformed water evaporator, or the air preheater on the side opposite to the fuel cell stack side of the fuel cell stack. It is characterized by that.

  According to such a configuration, heating is performed on the side opposite to the fuel cell stack side surface of the reformer, the reforming water evaporator, or the air preheater, which is disposed around the fuel cell stack in the heat insulation housing By providing the means, it is possible to uniformly heat the device with a sufficient heat transfer area. For this reason, the reformed fuel or air introduced into the fuel cell stack can be efficiently preheated, and the thermal efficiency of the entire system can be improved.

  The reformer, the reforming water evaporator, or the air preheater disposed around the fuel cell stack is disposed opposite to the end face of the fuel cell stack and disposed opposite to the end face of the fuel cell stack. If the heating means is provided on the side opposite to the side, the device can be efficiently heated by radiant heat from the fuel cell stack, and the other side is efficiently made using the heating means. Since it can be heated, the reformed fuel or air introduced into the fuel cell stack can be preheated more efficiently.

  The heating means may be a tubular heater or a planar heater. That is, since the heating means is provided on the surface of each device opposite to the fuel cell stack side, heat radiation such as radiant heat from the fuel cell stack is not directly received. Therefore, it is possible to use a general-purpose heater such as a tubular heater or a planar heater having a relatively low heat resistant temperature as the heating means, and the heating means can be configured at low cost.

  The heater control unit controls the output of the heating unit, and the heater control unit controls the output of the heating unit such that the reformer, the reformed water evaporator, or the air preheater has a target temperature. When controlled, the fuel cell module can be operated while maintaining high thermal efficiency.

  At least the reformer is disposed around the fuel cell stack in the heat insulation casing and the heating means is provided, and the heater control unit is configured to control the temperature of the catalyst stored in the reformer. The output of the heating unit may be controlled to achieve a target temperature. As a result, the efficiency of the reforming reaction in the reformer is improved, and further, the reformed fuel introduced into the fuel cell stack can be efficiently preheated, so that the thermal efficiency of the entire system can be further improved.

  ADVANTAGE OF THE INVENTION According to this invention, the reformed fuel or air introduce | transduced into a fuel cell stack can be efficiently preheated, and the thermal efficiency of the whole system can be improved.

FIG. 1 is a block diagram illustrating a configuration of a power generation device including a fuel cell module according to an embodiment of the present invention. FIG. 2 is a perspective view showing a configuration example of a fuel cell module according to an embodiment of the present invention. FIG. 3 is a plan view showing a schematic configuration of the fuel cell module shown in FIG. FIG. 4 is an explanatory view of the reformer as viewed from the front side. FIG. 5 is a flowchart showing an example of a startup procedure of the fuel cell module according to the present embodiment.

  Hereinafter, preferred embodiments of the fuel cell module according to the present invention will be described in detail with reference to the accompanying drawings.

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

  As shown in FIG. 1, the power generation apparatus 12 includes a fuel cell module 10 in which a fuel cell stack 14 is provided inside the heat insulating casing 16, fuel supply lines LF 1 and LF 2 for supplying fuel and air to the fuel cell module 10 and The air supply lines LA1 and LA2, the hot water heat exchanger 18 for producing hot water using exhaust heat from the fuel cell module 10, and water for generating reforming water vapor used in the fuel cell module 10 It is comprised as a cogeneration system provided with the condensed water tank 20 to store.

  The fuel cell module 10 is provided with a fuel cell stack 14, a reformer 22, an air preheater 24, and a reformed water evaporator (vaporizer) 26, and these are insulated as a box-shaped insulation member. It is installed in the inside (high temperature chamber) of the housing 16. A general heat insulating material such as glass wool may be used as the heat insulating member. However, the fuel cell module 10 can be configured more compactly by using a board-shaped high-performance heat insulating material.

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

  Raw fuel (for example, methane gas, city gas, etc.) from the fuel supply line LF1 passes through the desulfurizer 30 and the reformer 22 and becomes a reformed fuel containing hydrogen and carbon monoxide, and from the fuel supply line LF2 to the fuel electrode 14a And introduced. The reformer 22 may have a known configuration, and various reforming catalysts are provided therein. The reforming water evaporator 26 evaporates the water sent from the coagulation water tank 20 storing the coagulation water from the hot water heat exchanger 18 to generate reforming steam, and the generated steam is a steam supply line The fuel is introduced into the fuel supply line LF1 immediately before being introduced into the reformer 22 from the LW. As a result, the fuel is mixed with the steam that has become hot in the reforming water evaporator 26, for example, heated to about 300 ° C., and then introduced into the reformer 22, where the temperature rises to about 700 ° C., It is steam-reformed into a reformed fuel.

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

  The exhaust gas emitted from the fuel cell stack 14 is sent to the hot water heat exchanger 18 from the exhaust gas line LG. The hot water heat exchanger 18 heats the water supplied from the water storage tank 36 with the exhaust gas from the exhaust gas line LG to produce hot water, and the produced hot water is returned to the water storage tank 36. In the water storage tank 36, makeup water is supplied and warm water is taken out. Further, the exhaust gas that has passed through the hot water heat exchanger 18 is condensed and removed by the aggregated water tank 20 and exhausted. The condensed water is supplied to the reforming water evaporator 26 as reforming water. A level meter is installed in the cohesion water tank 20, and when the water falls below a certain level, make-up water is supplied, and when the water goes above a certain level, drainage occurs by overflow. Thereby, unnecessary gas and excess water are exhausted and drained.

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

  FIG. 2 is a perspective view showing an example of the configuration of a fuel cell module 10 according to an embodiment of the present invention, and FIG. 3 is a plan view showing a schematic configuration of the fuel cell module 10 shown in FIG. Hereinafter, with respect to each device constituting the fuel cell module 10, the front side in FIG. 2 is called the front side (front side), the back side is called the rear side (back side), and the left-right direction is called the width direction (horizontal width direction). I will explain it.

  As shown in FIG. 2, in the present embodiment, a fuel cell module 10 having a configuration of four fuel cells provided with four fuel cell stacks 14 in one heat insulating housing 16 is used. In the fuel cell module 10, two fuel cell stacks 14 are placed on the upper shelf 40a and the lower shelf 40b of the shelf device 40 installed in the heat insulating housing 16, and the arrangement of two rows and two rows in front view It has become. Hereinafter, such a set of four fuel cell stacks 14 may be collectively described as the fuel cell stack 14. The number of mounted fuel cell stacks 14 can be changed as appropriate.

  In the fuel cell module 10, a flat box-shaped reformer 22 is installed along the vertical direction so as to face the front of the fuel cell stack 14 mounted on the shelf device 40, and the fuel cell module 10 is flat above the fuel cell stack 14. A box-shaped reforming water evaporator 26 is installed, and an air preheater 24 is installed on the side surface of the fuel cell stack 14.

  In the fuel cell module 10, which is configured to be kept warm by the heat insulating housing 16, the reformer 22 requiring high temperature and the air preheater 24 are disposed on the side surface of the fuel cell stack 14 A quality water evaporator 26 is disposed above the fuel cell stack 14.

  The reformer 22 has a flat plate type structure having a flat plate type reforming reaction portion (catalyst layer) 22a in which various reforming catalysts are provided. The reformer 22 is disposed along the vertical direction in the heat insulating casing 16 and is in parallel with the fuel cell stack 14. The reformer 22 has such a flat plate structure and is disposed so as to cover the front of each fuel cell stack 14, and therefore can efficiently receive the heat generated from the fuel cell stack 14.

  FIG. 4 is an explanatory view of the reformer 22 viewed from the front side, and is a block explanatory view also showing a control system for controlling the output of the heater 64 provided in the reformer 22.

  As shown in FIGS. 3 and 4, the heater 64 is provided on an outer wall surface 22 b which is a surface of the reformer 22 opposite to the fuel cell stack 14 side. The heater 64 is a capillary-like heater in which a metal capillary (sheath) is filled with a heating wire and an insulating material, and has a structure that can be freely bent and used. In the present embodiment, the heater 64 is disposed on the outer wall surface 22b of the reformer 22 in a meandering manner and fixed by the fixing tool 66, so that the entire outer wall surface 22b can be uniformly heated. As shown by a two-dot chain line in FIG. 4, a planar heater 68 provided so as to cover substantially the entire outer wall surface 22 b may be used in place of the capillary heater 64.

  The heater 64 is connected to the heater control unit 70. The heater control unit 70 controls the output of the heater 64 based on the measurement values of the surface temperature sensor T1 that measures the surface temperature of the reformer 22 and the internal temperature sensor T2 that measures the internal temperature of the reformer 22. The surface temperature sensor T1 is provided on the outer wall surface 22b to detect the temperature of the outer wall surface 22b, and the internal temperature sensor T2 is provided on the reforming reaction portion 22a to detect the catalyst temperature of the reforming reaction portion 22a. . A fuel cell stack ambient temperature sensor T3 is further connected to the heater controller 70. The fuel cell stack ambient temperature sensor T3 detects the temperature around the fuel cell stack 14, and is provided in the vicinity of the fuel cell stack 14 as shown in FIG. 3, for example.

  The heater control unit 70 has a storage unit 72. In the storage unit 72, the target temperature (for example, 500 ° C.) of the outer wall surface 22b of the reformer 22 measured by the surface temperature sensor T1 and the target temperature inside the reformer 22 measured by the internal temperature sensor T2. (For example, 700 ° C.) and the target temperature (for example, 500 ° C.) of the exhaust gas measured by the fuel cell stack ambient temperature sensor T3 are stored. These target temperatures may be set and changed by input means (not shown).

  Next, the startup procedure of the fuel cell module 10 according to this embodiment will be described mainly with respect to output control of the heater 64 provided in the reformer 22. FIG. 5 is a flowchart showing an example of a startup procedure of the fuel cell module 10 according to the present embodiment.

  At the start of the fuel cell module 10, first, the heater 64 provided on the outer wall surface 22b of the reformer 22 is controlled to ON under control of the heater control unit 70 (step S1 in FIG. 5). As a result, the temperature of the outer wall surface 22b of the reformer 22 gradually increases.

  In step S2, the heater control unit 70 continues to determine whether the outer wall surface 22b of the reformer 22 has reached the target temperature (here, 500 ° C.) based on the detection result of the surface temperature sensor T1 (step S2). No) When the outer wall surface 22b reaches the target temperature (Yes in Step S2), Step S3 is subsequently executed.

  In step S3, under the control of a control device (not shown) that controls the entire fuel cell module 10 or the power generation device 12, introduction of raw fuel from the fuel supply line LF1 to the reformer 22, reforming water The introduction of the reforming steam generated by the evaporator 26 from the steam supply line LW is started, and the fuel reforming in the reforming reaction portion 22 a of the reformer 22 is started.

  Here, since the reforming reaction (steam reforming reaction) in the reformer 22 is an endothermic reaction, the temperature of the reformer 22 decreases as the reforming proceeds, and the reaction temperature in the fuel cell stack 14 also decreases. Do. Therefore, in order to compensate the reaction heat in the reformer 22 and secure the reaction temperature in the fuel cell stack 14, the heater control unit 70 detects the ambient temperature of the fuel cell stack 14 detected by the fuel cell stack ambient temperature sensor T3. The output of the heater 64 is increased to reach the target temperature (here, 500 ° C.), and the temperature of the outer wall surface 22b is increased (step S4). The heater 64 needs to be output-controlled so that the heat resistance temperature is, for example, 600 ° C. or less. When the heat resistance temperature is exceeded, the heater control unit 70 turns off the heater 64 (OFF).

  Then, the heater control unit 70 performs output control of the heater 64 so that the catalyst temperature inside the reformer 22 becomes the target temperature (here, 700 ° C.) based on the detection result of the internal temperature sensor T2. As a result, when the catalyst temperature reaches the target temperature and the start-up operation of the fuel cell module 10 is finished, the fuel cell module 10 is operated and controlled in the steady operation maintaining the power generation state, so the heater control unit 70 is detected by the internal temperature sensor T2. The output of the heater 64 is controlled so that the catalyst temperature inside the reformer 22 to be maintained is maintained at the target temperature (700 ° C. here). This prevents the reformed fuel from the reformer 22 from being introduced into the fuel electrode 14a at a low temperature of about normal temperature when the fuel cell module 10 (power generation device 12) is started, thereby deteriorating the fuel cell stack 14 And the occurrence of damage is prevented, and the reforming temperature during steady operation is secured, so that the thermal efficiency of the entire system is improved.

  As described above, in the fuel cell module 10 according to the present embodiment, the reformer 22 is disposed around the fuel cell stack 14 in the heat insulating housing 16, and the surface of the reformer 22 on the fuel cell stack 14 side A heater 64 (68), which is a heating means, is provided on the outer wall surface 22b, which is the opposite surface.

  Therefore, in the fuel cell module 10, the heater 64 provided on the outer wall surface 22b can uniformly heat the reformer 22 with a sufficient heat transfer area. Therefore, at startup, the catalyst temperature in the reformer 22 can be rapidly reached to the target temperature, and in steady state, the catalyst temperature in the reformer 22 can be stably maintained around the target temperature. Thereby, the reformed fuel introduced into the fuel cell stack 14 can be efficiently preheated, and the thermal efficiency of the entire system can be improved. Moreover, by heating the reformer 22 by the heater 64 at startup, the time until the temperature of the outer wall surface 22b of the reformer 22 rises to the target temperature of about 500 ° C. is shortened, so the fuel cell module 10 start-up time can be shortened.

  In this case, since the heater 64 is provided on the outer wall surface 22 b opposite to the fuel cell stack 14 side, heat radiation such as radiant heat from the fuel cell stack 14 is not directly received. For this reason, it is possible to use a general-purpose heater having a heat resistant temperature as low as 1000 ° C. or less, for example, and the cost of the heater 64 can be kept low.

  In addition to the reformer 22, an air preheater 24 and a reforming water evaporator 26 are disposed around the fuel cell stack 14 in the fuel cell module 10. Therefore, for example, the heater 64 (68) may be provided on the outer wall surface of the air preheater 24, and the heater 64 (68) may be provided on the outer wall surface (upper wall surface) of the box of the reforming water evaporator 26. That is, although the conditions differ depending on the specification of the fuel cell module 10, at least the side of the fuel cell stack 14 in all or some of the reformer 22, the air preheater 24, and the reforming water evaporator 26. And heater 64 (68), which is a heating means, on the opposite side to efficiently preheat the reformed fuel and air introduced into the fuel cell stack 14 and improve the thermal efficiency of the entire system at low cost, It is possible to shorten the startup time.

  In addition, for example, a fuel cell stack having a structure in which the remaining high temperature gas not consumed in the power generation reaction is freely released from the outer peripheral portion of the power generation cell, which is described in patent document "Japanese Patent Application Laid-Open No. 2006-86053" In this case, the exhaust gas is burned by reaction, and the heat efficiency of the entire system can be further improved by using this combustion heat.

  When the air preheater 24 is provided with the heater 64 (68), the heater control unit 70 sets the temperature of the outer wall surface of the air preheater 24 and the temperature of preheated air at the outlet as the target temperature. The output of (68) may be controlled. When the reformed water evaporator 26 is provided with the heater 64 (68), the heater control unit 70 sets the temperature of the outer wall surface of the reformed water evaporator 26 and the temperature of reforming steam at the outlet to the target temperature. It is preferable to control the output of the heater 64 (68) so that

  In addition, this invention is not limited to above-described embodiment, Of course, it can change freely in the range which does not deviate from the main point of this invention.

DESCRIPTION OF SYMBOLS 10 fuel cell module 12 power generation apparatus 14 fuel cell stack 14a fuel pole 14b air pole 16 heat insulation housing 22 reformer 22a reforming reaction part 22b outer wall surface 24 air preheater 26 reforming water evaporator 64, 68 heater 70 heater control T1 Surface temperature sensor T2 Internal temperature sensor T3 Fuel cell stack ambient temperature sensor

Claims (3)

A fuel cell module in which a fuel cell stack is arranged in a heat insulating housing,
A reformer disposed around the fuel cell stack in the heat insulating casing and reforming fuel supplied to the fuel cell stack ;
A heater provided on the opposite side to the fuel cell stack side surface before Kiaratameshitsu unit,
A heater control unit for controlling the output of the heater;
A surface temperature sensor for measuring the temperature of the outer wall of the reformer;
An internal temperature sensor for measuring the catalyst temperature inside the reformer;
A fuel cell stack ambient temperature sensor for measuring a surface temperature of the fuel cell stack;
With
During the start-up operation of the fuel cell module, the heater control unit causes the temperature of the outer wall of the reformer measured by the surface temperature sensor to reach a target temperature, and introduces raw fuel into the reformer. After being started, the output of the heater is controlled so that the ambient temperature of the fuel cell stack measured by the fuel cell stack ambient temperature sensor becomes a target temperature, and further, the modification measured by the internal temperature sensor is performed. A fuel cell module , wherein the output of the heater is controlled so that the catalyst temperature inside the mass device becomes a target temperature . The fuel cell module according to claim 1, wherein
Before Kiaratameshitsu unit is disposed opposite to an end face of the fuel cell stack, a fuel cell module, wherein the oppositely disposed surface on the end face of the fuel cell stack comprising the heater on the opposite side. The fuel cell module according to claim 1 or 2,
The fuel cell module, wherein the heater is a tubular heater or a planar heater.

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