TWI459624B - Fuel cell module - Google Patents

Description

Fuel cell module

The present invention relates to a fuel cell module that introduces raw fuel and air for power generation.

As one of the fuel cells, a solid oxide fuel cell (SOFC) is known. A general solid oxide fuel cell module having a reformer for reforming a hydrocarbon fuel (raw fuel) such as kerosene or urban pipeline gas to generate a hydrogen-containing gas (modified gas), by means of the reformer A fuel cell stack obtained by electrochemically generating a reaction between a modified gas and air. The fuel cell stack generally operates at a high temperature of about 550 to 1000 °C. These SOFC systems are described, for example, in Patent Document 1.

Patent Document 1: JP-A-2006-294508

However, the above prior art has the following problems. That is, the reforming reaction of the raw fuel requires various reactions such as steam reforming or partial oxidation reforming. For example, the steam reforming reaction is an extremely endothermic reaction, and the reaction temperature is about 550 to 750 ° C, which is relatively high, so a high temperature heat source is required. For this reason, it has been proposed to arrange a reformer in the vicinity of the fuel cell stack, and to heat the reformer using the radiant heat derived from the fuel cell stack and the heat of combustion of the exhaust gas as a heat source, but a sufficient high reformer temperature cannot be obtained. Therefore, the original fuel cannot be completely upgraded, and it is difficult to obtain the desired amount of hydrogen. Moreover, even if the original fuel is completely upgraded, the hydrogen concentration in the reformed gas generated by the reformer is not It is high enough to obtain the desired stack voltage, so it is difficult to increase the power generation efficiency.

An object of the present invention is to provide a fuel cell module capable of improving power generation efficiency.

The fuel cell module of the present invention is characterized in that: a reformer for reforming a raw fuel and generating a reformed gas, a fuel cell stack for generating electricity using a reformed gas generated by a reformer, and stacking the fuel cells The body is coupled to the reformer to conduct heat from the fuel cell stack to the heat transfer member of the reformer.

The fuel cell module of the present invention can not only conduct radiant heat derived from the fuel cell stack or the like to the reformer, but also can transfer heat generated by the fuel cell stack to the reformer via the heat conducting member. Thereby, the heat derived from the fuel cell is efficiently conducted to the reformer, and since the amount of heat transfer from the fuel cell stack to the reformer is increased, the temperature of the reformer is sufficiently increased. Thus, since the concentration of hydrogen in the reformed gas generated by the reformer is sufficiently increased, the voltage generated by the corresponding fuel cell stack is also increased. As a result, the power generation efficiency of the fuel cell module is improved.

Preferably, the fuel cell stack comprises a stack body composed of a plurality of stacked battery cells, a stack of stacked body bodies stacked in a stacking direction, and a heat conducting component for combining the end plates with the reformer. Settings. The end plates of the fuel cell stack are formed thicker than the electrodes or separators forming the constituent members of the cell stack of the stack body. Therefore, by combining the end plate and the reformer with the heat conducting member, it is possible to pass the heat transfer portion The heat transfer from the fuel cell stack to the reformer is performed with high efficiency.

Further, preferably, the heat conduction member has an elastomer structure. Therefore, when a metal having a high thermal conductivity is used as a material of the heat conduction member, thermal expansion by the heat conduction member can be sufficiently alleviated. Thermal stress caused by heat shrinkage.

Moreover, the fuel cell module of the present invention is characterized in that it has a reformer that reforms the raw fuel and generates a reformed gas, and a fuel cell stack that generates electricity by using the reformed gas generated by the reformer, and the fuel cell The stack is directly bonded to the reformer.

The fuel cell module of the present invention can not only conduct radiant heat derived from the fuel cell stack to the reformer, but also transfer heat generated by the fuel cell stack as conduction heat from the fuel cell stack to the reforming. Device. Thereby, the heat from the fuel cell stack is efficiently conducted to the reformer, and since the amount of heat transfer from the fuel cell stack to the reformer is increased, the temperature of the reformer is sufficiently increased. Thus, since the concentration of hydrogen in the reformed gas generated by the reformer is sufficiently increased, the voltage generated by the corresponding fuel cell stack is also increased. As a result, the power generation efficiency of the fuel cell module is improved.

Preferably, the fuel cell stack includes a stacked body formed by stacking a plurality of stacked cells, and the stacked body is sandwiched into the pair of end plates in a stacking direction, and the end plates are directly coupled to the reformer. As described above, by directly bonding the end plates thicker than the constituent members of the unit cell stack to the reformer, heat transfer from the fuel cell stack to the reformer can be performed with high efficiency.

Further, it is preferred that an electrically insulating member is interposed between the end plate and the body of the stack. The case where the reformer housing is formed of a conductive metal, the fuel cell The heat conducting component in combination with the reformer and the reformer will be formed of a highly thermally conductive metal. Once the fuel cell stack is directly coupled to the reformer, electrical energy flows from the fuel cell stack to the reformer. By electrically insulating the components between the end plates and the body of the stack, the energization of the fuel cell stacks to the reformer can be avoided.

According to the present invention, a high performance fuel cell module with improved power generation efficiency can be obtained.

Hereinafter, preferred embodiments of the fuel cell module of the present invention will be described in detail based on the drawings.

Fig. 1 is a system configuration diagram of a fuel cell system according to a first embodiment of the fuel cell module of the present invention. The fuel cell module 1 of the embodiment of the present invention includes a reformer that reforms a modified raw material (raw fuel) to generate a reformed gas, and a flat plate that generates electricity by using the reformed gas obtained by the reformer 2 and air. A solid oxide fuel cell (SOFC) stack 3, a module container 4 housing the reformer 2 and the SOFC stack 3.

The reformer 2 generates a steam reforming reaction of the modified raw material in which the raw fuel and the water vapor are mixed, thereby generating a reformed gas containing hydrogen and carbon monoxide. The steam reforming reaction is a very large endothermic reaction, and the reaction temperature is about 550 to 750 ° C, which is high, so a high temperature heat source is required. To this end, the reformer 2 is disposed in the vicinity of the SOFC stack 3, and the steam reforming reaction is performed using the radiant heat derived from the SOFC stack 3 and the heat of combustion of the exhaust gas. Further, the SOFC stack 3 is usually operated at a high temperature of about 550 to 1000 °C.

The reformer 2 is connected to supply raw materials for supplying the modified raw materials to the reformer 2 Give the line 5. As the raw fuel system, a hydrocarbon fuel such as kerosene or city pipe gas is used. In the raw material supply system 5, for example, water vapor obtained by a water vaporizer (not shown) is mixed with a raw fuel gas obtained by a fuel gasifier (not shown) to generate a reformed raw material gas. Thereafter, the modified raw material gas is introduced into the reformer 2 through the raw material introduction pipe 6. Further, the raw material supply system 5 has an electromagnetic valve 7 that adjusts the supply amount of the raw fuel, and an electromagnetic valve 8 that adjusts the supply amount of the steam.

The SOFC stack 3 is connected to the reformer 2 by a reforming gas supply pipe 9. Further, an air introduction pipe 11 for introducing air derived from the air fan 10 is connected to the SOFC stack 3. The air introduction pipe 11 is provided with a solenoid valve 12 for adjusting the amount of air introduced.

The SOFC stack 3 has a stack body 14 in which a plurality of unit cell stacks 13 are laminated, a pair of end plates 15 in which the stack body 14 is sandwiched in the lamination direction, and a partition body respectively present in the stack body An insulating plate 16 between each of the end plates 15.

As shown in FIG. 2, the cell stack 13 has an anode (fuel electrode) 17, a cathode (air electrode) 18, an electrolyte 19 disposed between the anode 17 and the cathode 18, and an outer side of the anode 17 and the cathode 18, respectively. The separator 20 is configured. The reformed gas derived from the reformer 2 is introduced into the anode 17, and the air derived from the air fan 10 is introduced into the cathode 18. Thereby, an electrochemical power generation reaction can be performed in each of the unit cell stacks 13.

The end plate 15 is formed of, for example, a metal such as a stainless steel mesh (SUS). The thickness of the end plate 15 is much greater than the thickness of the separator 20. The insulating plate 16 is a plate formed of an electrically insulating material such as alumina, and is interposed between the end plate 15 and the separator 20 between.

Each of the end plates 15 of the SOFC stack 3 and the casing 2a of the reformer 2 are respectively coupled by a heat conducting member 21 that conducts heat of the SOFC stack 3 to the reformer 2. One of the heat conduction members 21 is coupled to the vicinity of the connection portion (modified gas outlet) of the reforming gas supply pipe 9 of the reformer 2. The heat conduction member 21 is formed of a material having high thermal conductivity and high heat resistance temperature such as SUS or Inconel alloy (trade name of a nickel-based alloy containing chromium and iron) or a metal such as nickel.

Here, since the insulating plate 16 is interposed between the stacked body 14 of the SOFC stack 3 and the end plate 15, even if the case 2a of the reformer 2 is formed of a conductive metal, the SOFC stack 3 is electrically connected. Flow to the reformer 2 also does not affect the reformer 2.

Further, since the heat conduction resistance is smaller as the cross-sectional area of the heat conduction member 21 is larger, the heat conduction member 21 is preferably in the heat flow direction, and has a shape in which the cross-sectional area gradually increases from the SOFC stack 3 to the reformer 2 in this direction. .

Furthermore, as the heat conduction member 21, the thermal expansion is moderated. The thermal stress generated by heat shrinkage is preferably such that the elastic modulus such as a porous metal or a metal porous body is low.

When the fuel cell module 1 of the above operation is operated, water vapor and raw fuel are supplied to the reformer 2, and the reformed gas is generated by the reformer 2, and the reformed gas is supplied through the reformed gas supply pipe 9. To the anode 3a of the SOFC stack 3. Further, air derived from the air fan 10 is supplied to the cathode 3b of the SOFC stack 3. Thereafter, when the SOFC stack 3 is heated to a certain temperature, the SOFC stack 3 starts to generate electricity by drawing current from the SOFC stack 3.

At this time, since the temperature of the reformer 2 is higher, the reformer generated by the reformer 2 is modified. The higher the concentration of hydrogen contained in the gas, the higher the voltage generated by the SOFC stack 3, and the higher the power generation efficiency. Therefore, by increasing the temperature utilization ratio of the following formula, by increasing the temperature of the SOFC stack 3, it is necessary to operate by increasing the amount of heat radiation conducted by the SOFC stack 3 to the reformer 2. .

However, since the constituent material of the SOFC stack 3 always has a heat-resistant temperature, there is a limit to raising the temperature of the SOFC stack 3, and it is difficult to sufficiently increase the amount of heat radiation from the SOFC stack 3 to the reformer 2. Thus, the temperature of the reformer 2 cannot be sufficiently raised only by the radiant heat originating from the SOFC stack 3 and the heat of combustion of the exhaust gas. Further, when the heater or the burner for heating the reformer 2 is placed in the module container 4, the structure of the fuel cell module becomes complicated and the cost increases.

In the present embodiment, the end plate 15 of the SOFC stack 3 and the casing 2a of the reformer 2 are combined by the heat conducting member 21, except that the radiant heat and the exhaust gas combustion heat derived from the SOFC stack 3 are transferred to In addition to the reformer 2, the heat generated by the SOFC stack 3 is also conducted as conduction heat from the end plate 15 to the reformer 2 via the heat transfer member 21. Thereby, since the total amount of heat conducted by the SOFC stack 3 to the reformer 2 is increased, the temperature of the reformer 2 is sufficiently increased. At this time, by coupling the heat conduction member 21 to the vicinity of the reforming gas outlet of the reformer 2, since the temperature in the vicinity of the reforming gas outlet of the reformer 2 rises remarkably, it is in the reformed gas generated by the reformer 2. The concentration of hydrogen contained is increased Big. Thus, since the stack body voltage generated by the SOFC stack 3 is sufficiently increased, the power generation efficiency of the fuel cell module 1 is improved.

Here, as described above, if the amount of heat transfer from the SOFC stack 3 to the reformer 2 is increased, the temperature of the SOFC stack 3 will be lowered. Therefore, by reducing the flow rate of the air supplied to the SOFC stack 3 and improving the air utilization rate (refer to the above formula (A)), the temperature of the SOFC stack 3 can be raised. Such a reduction in the supply amount of air can reduce the power consumption of the air fan 10, and as a result, the power generation efficiency of the fuel cell module 1 can be further improved.

Further, since the SOFC stack 3 is connected to the reformer 2 by the heat conducting member 21, since the heat transfer of the SOFC stack 3 to the reformer 2 can be performed with high efficiency, the heating for heating the reformer 2 is not particularly provided. The temperature of the reformer 2 can also be sufficiently increased under the condition of a simple configuration, such as a burner or a burner. According to this, it is possible to prevent an increase in cost or an increase in size of the module.

Fig. 3 is a system configuration diagram of a fuel cell system according to a second embodiment of the fuel cell module of the present invention. In the drawings, the same or equivalent components and elements as those in the first embodiment are denoted by the same reference numerals, and their description is omitted.

In the same figure, the fuel cell module 30 of the present embodiment has the reformer 2, the SOFC stack 3, and the module container 4 similar to those of the first embodiment. The end plates 15 of the SOFC stack 3 are directly bonded to the casing 2a of the reformer 2. The other configuration is the same as that of the first embodiment.

According to the present embodiment, the heat generated by the SOFC stack 3 can be conducted as conduction heat from the end plate 15 to the reformer 2. In this case as well, since the total amount of heat transferred from the fuel cell stack 3 to the reformer 2 is increased, the temperature of the reformer 2 is sufficiently increased. Thereby, as in the first embodiment, the fuel can be made The power generation efficiency of the pool module 30 is improved.

Further, the present invention is not limited to the above embodiment. For example, the structure of the above embodiment is such that the insulating body 16 is interposed between the stacked body 14 of the SOFC stack 3 and each of the end plates 15, but if the housing 2a or the heat conducting member 21 of the reformer 2 is electrically In the case where the insulating material is formed, the insulating plate 16 may not be particularly provided.

Further, in the above embodiment, the SOFC stack 3 is a flat plate structure, but the present invention is also applicable to a fuel cell module having a cylindrical SOFC bundle (stack). Further, in the cylindrical SOFC bundle, the individual battery cell stacks are connected to each other by an interconnecting pipe. In the case of this type, for example, the storage container of the cylindrical bundle and the casing 2a of the reformer 2 may be joined or directly joined by the heat conducting member.

Further, the above embodiment relates to a solid oxide fuel cell (SOFC). However, the present invention can also be applied to, for example, a molten carbonate fuel cell (MCFC) of a high-temperature fuel cell similar to SOFC.

Industrial use possibility

According to the present invention, damage to the fuel cell can be avoided with a simple configuration when the power generation of the solid oxide fuel cell is stopped.

1‧‧‧ fuel cell module

2‧‧‧Modifier

2a‧‧‧shell

3‧‧‧Solid oxide fuel cell (SOFC) stack

4‧‧‧Modular Container

5‧‧‧Material supply system

6‧‧‧Material introduction tube

7‧‧‧ solenoid valve

8‧‧‧ solenoid valve

9‧‧‧Modifier body supply pipe

10‧‧‧Air fan

11‧‧‧Air inlet tube

12‧‧‧ solenoid valve

13‧‧‧Single cell stack

14‧‧‧Stack body

15‧‧‧End board

16‧‧‧Insulation board (electrical insulation parts)

21‧‧‧Heat conductive parts

30‧‧‧ fuel cell module

Fig. 1 is a system configuration diagram of a fuel cell system according to a first embodiment of the fuel cell module of the present invention.

Fig. 2 is an exploded perspective view showing the unit cell stack shown in Fig. 1.

Fig. 3 is a system configuration diagram of a fuel cell system according to a second embodiment of the fuel cell module of the present invention.

1‧‧‧ fuel cell module

2‧‧‧Modifier

2a‧‧‧shell

3‧‧‧SOFC stack

4‧‧‧Modular Container

5‧‧‧Material supply system

6‧‧‧Material introduction tube

7‧‧‧ solenoid valve

8‧‧‧ solenoid valve

9‧‧‧Modifier body supply pipe

10‧‧‧Air fan

11‧‧‧Air inlet tube

12‧‧‧ solenoid valve

13‧‧‧Single cell stack

14‧‧‧Stack body

15‧‧‧End board

16‧‧‧Insulation board

21‧‧‧Heat conductive parts

Claims (5)

A fuel cell module characterized by comprising: a reformer that reforms a raw fuel and generates a reformed gas; a fuel cell stack that generates electricity by using the reformed gas generated by the reformer; and the fuel The battery stack is disposed in combination with the reformer, and transfers the heat of the fuel cell stack to the heat transfer member of the reformer; the fuel cell stack has a stack body formed by laminating a plurality of battery cells And sandwiching the stacked body body into the disposed pair of end plates in a lamination direction; and the heat conducting member is configured to couple the end plate to the reformer. The fuel cell module of claim 1, wherein the heat conducting member has an elastomeric configuration. The fuel cell module of claim 1, wherein an electrically insulating member is interposed between the end plate and the body of the stack. A fuel cell module characterized by comprising: a reformer for reforming a raw fuel and generating a reformed gas, and a fuel cell stack for generating electricity by using the reformed gas generated by the reformer; the fuel cell The stack is directly coupled to the reformer; the fuel cell stack has a stack body formed by laminating a plurality of unit cell stacks, and the stack body is laminated The direction is sandwiched into the pair of end plates of the configuration; and the end plates are directly combined with the above-mentioned reformer. The fuel cell module of claim 4, wherein an electrically insulating member is interposed between the end plate and the body of the stack.