JP2009076275A - Fuel cell module - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a fuel cell module that achieves a more uniform temperature distribution inside a module. <P>SOLUTION: Inside an internal container 107, fuel cell stacks 101 are arranged on the lower side (on the ground side) while a burner 106, a reformer 102, a fuel preheater 105, a water-vapor generator 104, and an air preheater 103 are arranged thereabove. The fuel cell stacks 101 are arranged on the lower side of the internal container 107 partitioned by a flameproof wall 109, while the burner 106, the reformer 102, the fuel preheater 105, the water-vapor generator 104, and the air preheater 103 are arranged on the upper side. <P>COPYRIGHT: (C)2009,JPO&INPIT

Description

  The present invention relates to a fuel cell module that is mounted on a fuel cell system and generates electric power.

  In recent years, high efficiency has been obtained regardless of the size of the scale, and therefore, fuel cells have attracted attention as power generation means used in next-generation cogeneration systems (see Non-Patent Document 1). A fuel cell is a battery that uses a chemical reaction between an oxidant gas such as oxygen and a fuel gas such as hydrogen, and a single cell in which an electrolyte layer is sandwiched between an anode called an air electrode and a cathode called a fuel electrode, It is used as a stacked cell stack.

  In such a fuel cell system, in order to realize high power generation efficiency, there is a configuration of a fuel cell module that can efficiently manage heat generated from the cell stack of the fuel cell and combustion heat of the fuel electrode exhaust gas. Necessary. In particular, in the case of a high-temperature fuel cell such as a solid oxide fuel cell, requirements for heat insulation and heat insulation are strict, and realization of an efficient fuel cell module is strongly demanded.

  Here, the configuration of a well-known fuel cell module will be briefly described. FIG. 3 is a configuration diagram showing a schematic configuration of such a fuel cell module. The fuel cell module includes a fuel cell stack 301, a reformer 302, an air preheater 303, a steam generator 304, a fuel preheater 305, a burner 306, and the like.

  Hereinafter, the operation of the fuel cell module will be described. First, air necessary for power generation by the fuel cell stack 301 is subjected to processes such as filtering, pressurization, and low-temperature preheating by another device (not shown) in the fuel cell system including the module. It is supplied to the air preheater 303. Thus, the air supplied to the air preheater 303 is heated to a temperature suitable for power generation by the air preheater 303 and supplied to the fuel cell stack 301. The temperatures suitable for power generation are, for example, 150 ° C. to 200 ° C. for phosphoric acid fuel cells and 550 ° C. to 650 ° C. for molten carbonate fuel cells.

  Next, the water is supplied to the steam generator 304 through processes such as filtering and low-temperature preheating by other devices (not shown) in the fuel cell system including the module. The water thus supplied to the steam generator 304 is converted into steam necessary for reforming fuel such as city gas by the steam generator 304.

  In addition, city gas as fuel is condensed into water vapor by low-temperature preheating after processing such as pressurization, low-temperature preheating, and desulfurization by other devices (not shown) in the fuel cell system including this module. The temperature is raised above the temperature and then supplied to the fuel preheater 305. Thereafter, the fuel preheater 305 raises the temperature to a temperature suitable for the operation of the reformer 302, and the steam from the steam generator 304 is mixed and supplied to the reformer 302.

  The burner 306 is supplied with fuel electrode exhaust gas and air electrode exhaust gas supplied from the fuel cell stack 301, and these gases are combusted. Heat from this combustion is supplied to the reformer 302. The reformer 302 reforms the supplied fuel mixed with water vapor by the heat supplied from the burner 306, generates a reformed gas mainly composed of hydrogen, and uses the generated reformed gas as a fuel. The battery cell stack 301 is supplied.

  Further, in the fuel cell stack 301, power is generated by the air supplied from the air preheater 303 and the reformed gas supplied from the reformer 302 to generate (generate) DC power. The direct-current power generated in this way is converted into electric power of a desired voltage by a power conversion device mounted on a fuel cell system such as an inverter (not shown) and supplied to the load. In this way, a desired power generation operation can be performed by combining the conventional fuel cell module with other mounted devices of the fuel cell system.

“Fuel Cell Power Generation”, edited by the Institute of Electrical Engineers of Fuel Cell Operation Research Committee, Corona Inc. 216-223, 1994.

  However, the fuel cell module as described above is composed of many devices, and heat exchange between the devices is complicated. For this reason, in the conventional fuel cell module, when the arrangement of the devices is not optimized, there is a problem that a local temperature rise or temperature drop occurs in the module and hinders normal operation.

  The present invention has been made to solve the above-described problems, and an object thereof is to make the temperature distribution in the module more uniform.

  A fuel cell module according to the present invention includes a fuel cell stack composed of a plurality of single cells provided with an air electrode, an electrolyte, and a fuel electrode, a preheater for preheating gas supplied to the fuel cell stack, and a fuel cell. And a container for housing the cell stack and the preheater, and the preheater is disposed above the fuel cell stack inside the container. The preheater is heated by the heat generated from the fuel cell stack and rising.

  The fuel cell module may further include a partition having a plurality of openings disposed between a lower region of the container in which the fuel cell stack is disposed and an upper region of the container in which the preheater is disposed. Good.

  In the fuel cell module, the reformer is disposed between the fuel cell stack and the preheater and burns the air electrode exhaust gas discharged from the air electrode and the fuel electrode exhaust gas discharged from the fuel electrode to heat the reformer. A burner, a reformer that is disposed above the burner and reforms the fuel gas supplied to the fuel electrode, and a steam generator that is disposed above the burner and supplies steam to the reformer. . The preheater is an air preheater that preheats air supplied to the air electrode and an air preheater that preheats fuel supplied to the fuel electrode.

  As described above, according to the present invention, the preheater is disposed above the fuel cell stack inside the container, and the preheater is caused by the heat generated and raised from the fuel cell stack. Since the heating is performed, an excellent effect that the temperature distribution in the module becomes more uniform can be obtained.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS. 1 and 2. FIG. 1 is a configuration diagram showing a configuration of a fuel cell module according to an embodiment of the present invention. FIG. 1 schematically shows a cross section. FIG. 2A is a perspective view showing the inside of the fuel cell module, and FIG. 2B is a perspective view showing the configuration of each device arranged inside.

  The fuel cell module in the present embodiment first includes a plurality of fuel cell stacks 101, a reformer 102, an air preheater 103, a steam generator 104, a fuel preheater 105, and a burner 106. In addition, the fuel cell module includes an inner container 107 that accommodates the above-described components, and a heat insulating container 108 that accommodates the inner container 107. Between the inner container 107 and the heat insulating container 108 configured in this manner, an exhaust gas circulation layer 110 is formed in a space formed by a predetermined interval to form a double structure. Further, a heat insulating container exhaust port 181 is provided at the bottom of the heat insulating container 108, and an exhaust pipe 111 is connected thereto.

  The inner container 107 includes a side and bottom inner container partition wall 171 and an upper inner container exhaust partition wall 172, and the inner container exhaust partition wall 172 is provided with a plurality of inner container exhaust ports 172a. The inner container exhaust wall 172 may be, for example, a mesh structure. Therefore, the inner side of the inner container 107 communicates with the exhaust gas circulation layer 110 through the inner container exhaust port 172a. The exhaust gas circulation layer 110 communicates with the outside through a heat insulating container exhaust port 181 and an exhaust pipe 111. Therefore, the inner side of the inner container 107 communicates with the outside via the inner container exhaust port 172a, the exhaust gas circulation layer 110, the heat insulating container exhaust port 181, and the exhaust pipe 111.

  In addition, the inner container 107 is provided with a flame barrier (partition) 109 that serves as a partition that divides the interior into a lower side (ground side) and an upper side. The flame barrier 109 may include a plurality of openings, for example, a mesh-like structure. Inside the inner container 107, the lower side and the upper side communicate with each other through the opening of the flame barrier 109. The flame barrier 109 is made of a material having high thermal conductivity such as stainless steel and having high heat resistance capable of withstanding a high temperature of 700 to 1000 ° C.

  Inside the inner container 107, the fuel cell stack 101 is disposed on the lower side (ground side), and above this, the burner 106, the reformer 102, the fuel preheater 105, the steam generator 104, and the air preheater 103 are disposed. Is arranged. Accordingly, each preheater is disposed above the fuel cell stack 101 inside the inner container 107. Further, the burner 106 is disposed between the fuel cell stack 101 and each preheater, and the reformer 102 and the steam generator 105 are disposed above the burner 106.

  The fuel cell stack 101 is disposed below the inner container 107 partitioned by the flame barrier 109, and the burner 106, the reformer 102, the fuel preheater 105, the steam generator 104, and the air are disposed above. The preheater 103 is arranged. Here, the operating temperature of the solid oxide fuel cell is as high as 700 to 1000 ° C., and the heat transfer from the fuel cell stack 101 is mainly due to radiation rather than convection. The radiant heat from the side where the fuel cell stack 101 is disposed heats the flame barrier 109, and the radiant heat from the heated flame barrier 109 becomes more uniform. Thus, by providing the flame barrier 109, the heat from the fuel cell stack 101 arranged in the lower region is transmitted to each device in the upper region in a more uniform state.

  The inner container 107 is made of a material having high heat conductivity such as stainless steel and having high heat resistance capable of withstanding a high temperature of 700 to 1000 ° C. The heat insulating container 108 is made of a ceramic material such as alumina or mullite or a heat resistant heat insulating material such as a porous body thereof.

  Next, the operation of the fuel cell module configured as described above will be described. First, air necessary for power generation by the fuel cell stack 101 is subjected to processes such as filtering, pressurization, and low-temperature preheating by other devices (not shown) in the fuel cell system including this module. The air preheater 103 is supplied through the air supply path 112. The air thus supplied to the air preheater 103 is heated to a temperature suitable for power generation by the air preheater 103 and supplied to the fuel cell stack 101. The temperatures suitable for power generation are, for example, 150 ° C. to 200 ° C. for phosphoric acid fuel cells and 550 ° C. to 650 ° C. for molten carbonate fuel cells.

  Next, the water is supplied to the steam generator 104 through the water supply path 113 through processes such as filtering and low-temperature preheating by other devices (not shown) in the fuel cell system including the module. The The water supplied to the steam generator 104 in this way is converted into steam necessary for reforming fuel such as city gas by the steam generator 104.

  In addition, city gas as fuel is condensed into water vapor by low-temperature preheating after processing such as pressurization, low-temperature preheating, and desulfurization by other devices (not shown) in the fuel cell system including this module. After the temperature is raised above the temperature, the fuel is supplied to the fuel preheater 105 through the fuel supply path 114. Thereafter, the fuel preheater 105 raises the temperature to a temperature suitable for the operation of the reformer 102, and the steam from the steam generator 104 is mixed and supplied to the reformer 102.

  The reformer 102 reforms the supplied fuel mixed with water vapor mainly by the heat supplied from the burner 106, generates a reformed gas mainly composed of hydrogen, and the generated reformed gas Is supplied to the fuel cell stack 101.

  In the fuel cell stack 101, power is generated by the air supplied from the air preheater 103 and the reformed gas supplied from the reformer 102 to generate (generate) DC power. The direct-current power generated in this way is converted into electric power of a desired voltage by a power conversion device mounted on a fuel cell system such as an inverter (not shown) and supplied to the load.

  Further, as a result of power generation, fuel electrode exhaust gas and air electrode exhaust gas are discharged from the fuel cell stack 101. Among these exhaust gases, part of the fuel electrode exhaust gas is recycled to the reformer 102 and reused. Further, the other part (remaining) of the fuel electrode exhaust gas and the air electrode exhaust gas are supplied to the burner 106 and combusted. The air electrode exhaust gas is directly discharged into the inner container 107 and supplied to the burner 106 on the upper side of the inner container 107 through the opening of the flame barrier 109. On the other hand, the fuel electrode exhaust gas is supplied to the reformer 102 and the burner 106 through the fuel electrode exhaust gas recycle route 115 by a predetermined pipe.

  By the power generation operation as described above, first, heat and high-temperature air electrode exhaust gas are generated from the fuel cell stack 101 on the lower side inside the inner container 107, and these are disposed on the upper side through the flame barrier 109. Has been supplied to. Further, heat is generated by the burner 106 on the upper side inside the inner container 107. A part of the air electrode exhaust gas discharged from the fuel cell stack 101 described above is consumed by the burner 106 and then heated by the generated heat to become a high temperature. Further, the heat supplied from the fuel cell stack 101 and the burner 106 preheats the gas supplied to the fuel cell stack 101 such as the reformer 102, the air preheater 103, the steam generator 104, and the fuel preheater 105. The preheater is heated.

  As described above, the gas (exhaust gas) in the inner container 107 containing the air electrode exhaust gas is heated by the fuel cell stack 101 and the burner 106 to rise inside the inner container 107, and the inside of the inner container exhaust partition 172. The gas is discharged to the exhaust gas circulation layer 110 through the container exhaust port 172a. The high-temperature exhaust gas discharged to the exhaust gas circulation layer 110 flows downward in the exhaust gas circulation layer 110 so as to wrap around the inner container 107, and is discharged to the exhaust pipe 111 from the heat insulation container exhaust port 181 to enter the fuel cell system. It is supplied to a low-temperature preheater and a heat recovery device (not shown) to be mounted.

  According to the fuel cell module in the present embodiment described above, fuel serving as a heat source for the reformer 102, the air preheater 103, the water vapor generator 104, and the fuel preheater 105 inside the inner container 107. The battery cell stack 101 is in a state arranged below. The gas inside the inner container 107 heated by the heat generated from the fuel cell stack 101 rises inside the inner container 107. In this direction, the reformer 102, the air preheater 103, the steam The generator 104 and the fuel preheater 105 are arranged.

  Therefore, according to the present fuel cell module, the heat generated from the fuel cell stack 101 can be efficiently used for heating the reformer 102, the air preheater 103, the steam generator 104, and the fuel preheater 105. It becomes like this. The same applies to the heat generated from the burner 106. In addition, by disposing the fuel cell stack 101 at the bottom of the inner container 107, it is possible to suppress the formation of a local temperature gradient in the module (inner container 107). These effects can be obtained without complicating the system (module) or greatly increasing the number of parts.

  Further, according to the fuel cell module of the present embodiment described above, the exhaust gas discharged from the inner container 107 via the inner container exhaust partition 172 is exhausted inside the heat insulating container 108 without being directly discharged outside. It is discharged to the outside through the heat insulating container exhaust port 181 via the circulation layer 110. For this reason, the exhaust gas generated inside the fuel cell module (inner container 107) has a longer time without lowering the exhaust gas discharge flow rate, compared with the case where the exhaust gas is directly discharged outside without passing through the exhaust gas circulation layer 110. And discharged from the heat insulating container 108 to the outside. In addition, the exhaust gas discharged | emitted via the inner side container exhaust partition 172 will pass the exhaust gas distribution layer 110 with a narrow cross-sectional area, and a flow velocity will become quick.

  As described above, since the exhaust gas having a high temperature flows through the exhaust gas circulation layer 110, the temperature in the inner container 107 can be made more uniform, and the module (inner container 107) can be locally The formation of a typical temperature gradient can be suppressed, and the heat retention effect inside the module can be improved. For example, when there is no inner container partition wall 171 and the exhaust gas circulation layer 110 is not formed, a temperature gradient that decreases as the distance from the fuel cell stack 101 of the heat source increases in the space from the fuel cell stack 101 to the inner surface of the heat insulating container 108. Is formed. On the other hand, when the exhaust gas circulation layer 110 is formed and the high temperature exhaust gas flows here, the vicinity of the inner surface of the heat insulating container 108 away from the heat source is also in a high temperature state, and the temperature gradient becomes slow. These effects can be obtained without complicating the system (module) or greatly increasing the number of parts.

  A fuel cell module is composed of many devices, and heat exchange between the devices is complicated. Therefore, if the arrangement of each device is not optimized, a local temperature rise or temperature drop occurs in the module. It will interfere with normal operation. Such a problem can be solved by the above-described fuel cell module in the present embodiment, and the temperature distribution in the module can be made more uniform.

  Further, in the fuel cell module according to the present embodiment, city gas as fuel supplied from the outside to the fuel preheater 105 can be supplied to the burner 106 through the burner fuel supply path 116. Therefore, for example, when the fuel cell is started, the air is supplied to the inside of the inner container 107 via the air supply path 112, the air preheater 103, and the fuel cell stack 101, and the fuel supply path 116 for the burner. It is possible to cause the burner 106 to perform a combustion operation by using the fuel. Thereby, the temperature of each part in the fuel cell module can be increased.

  After each component of the fuel cell module becomes operable, as described above, the supply of fuel gas (city gas) to the fuel preheater 105 is started, and the supply of water is started and modified. The operation of the mass device 102 may be started and the power generation operation may be started. When the fuel cell exhaust gas is discharged from the fuel cell stack 101 after the power generation operation is started in this way, the supply of city gas through the burner fuel supply path 116 may be stopped and the operation may be shifted to a steady operation.

It is a block diagram which shows the structure of the fuel cell module in embodiment of this invention. It is the perspective view (a) which shows the inside of a fuel cell module, and the perspective view (b) which shows the structure of each apparatus arrange | positioned inside. It is a block diagram which shows the schematic structure of the conventional fuel cell module.

Explanation of symbols

  DESCRIPTION OF SYMBOLS 101 ... Fuel cell stack, 102 ... Reformer, 103 ... Air preheater, 104 ... Steam generator, 105 ... Fuel preheater, 106 ... Burner, 107 ... Inner vessel, 108 ... Heat insulation vessel, 109 ... Flame barrier (Partition), 110 ... exhaust gas circulation layer, 111 ... exhaust pipe, 112 ... air supply path, 113 ... water supply path, 114 ... fuel supply path, 115 ... fuel electrode exhaust gas recycle path, 116 ... fuel supply path for burner, 171 ... inner container partition, 172 ... inner container exhaust partition, 172a ... inner container exhaust port.

Claims (4)

A fuel cell stack comprising a plurality of single cells each having an air electrode, an electrolyte, and a fuel electrode;
A preheater for preheating gas supplied to the fuel cell stack;
A container for accommodating the fuel cell stack and the preheater,
The fuel cell module, wherein the preheater is disposed above the fuel cell stack inside the container. The fuel cell module according to claim 1, wherein
A fuel comprising a partition having a plurality of openings disposed between a lower region of the container in which the fuel cell stack is disposed and an upper region of the container in which the preheater is disposed. Battery module. The fuel cell module according to claim 1 or 2,
A burner that is disposed between the fuel cell stack and the preheater and burns the air electrode exhaust gas discharged from the air electrode and the fuel electrode exhaust gas discharged from the fuel electrode to heat the reformer. When,
A reformer that is disposed above the burner and reforms the fuel gas supplied to the fuel electrode;
A fuel cell module comprising: a steam generator disposed above the burner for supplying steam to the reformer. The fuel cell module according to any one of claims 1 to 3,
The preheater is
An air preheater that preheats air supplied to the air electrode and an air preheater that preheats fuel supplied to the fuel electrode.