JP2005063883A - Fuel cell system - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a system capable of carrying out a stopping process without using inactive gas even in a power failure, in a fuel cell system. <P>SOLUTION: This fuel cell system is composed of: a fuel cell 11 for generating power by using a fuel gas containing supplied hydrogen and an oxidizer gas such as air; an oxidizer supply passage 12 for supplying the oxidizer gas; a fuel supply passage 13 for supplying the fuel gas; a steam generation means 14 connected to the supply passage 13 on the upstream side relative to the fuel cell 11; a purge water passage 15 for supplying water to the generation means 14; a purge water tank 16 for storing water; a shut-off valve for closing the valve in a current-carrying period and opening the valve in a period without carrying a current as a purge water supply means 17 for supplying water to the generation means 14. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a fuel cell system that generates power using a fuel cell.

  Conventionally, purging of combustible gas in the system with an inert gas such as nitrogen or water vapor replacing the inert gas has been performed for safety during the shutdown process of the fuel cell system (see, for example, Patent Document 1). .

The configuration is shown in FIG. In FIG. 4, the fuel cell 11 generates electric power by a reaction between a fuel gas supplied through an oxidant supply path 12 and a fuel supply path 13 and an oxidant gas such as air. The fuel generation unit 22 heats a raw material such as natural gas supplied from the outside in an atmosphere including water vapor to generate a fuel gas including hydrogen, and supplies the fuel cell 11 with the fuel gas. During the stop process of the fuel cell system, the temperature is controlled by the control means 21, the water supply means 25 supplies water vapor to the fuel generation means 22, purges, and then the temperature of the fuel generation means 22 measured by the temperature measurement means 18. When the temperature becomes equal to or lower than the oxidation temperature of the reforming catalyst, the air supply means 26 supplies air to the fuel generation means 22 to purge the fuel cell system.
Japanese Patent Laid-Open No. 2002-8701 (page 8, FIG. 4)

  In the purging method in the fuel cell system as described above, purging without using an inert gas is performed for normal operation stop processing, but the purging operation / control is complicated and requires electric power. At the time of the operation stop processing, purging using an inert gas is performed. Therefore, a means for supplying an inert gas must be separately installed inside and outside the fuel cell system, resulting in an increase in installation space and cost.

  In order to solve this problem, a fuel cell system according to a first aspect of the present invention includes a fuel cell that generates power using fuel and an oxidant, an oxidant supply path for supplying an oxidant to the fuel cell, and the fuel cell. A fuel supply path for supplying fuel to the fuel cell, a steam generation means connected to the fuel supply path upstream from the fuel cell, a purge water path connected to the steam generation means for supplying water, and a purge water path Purge water supply means for supplying water to the water vapor generation means, and a purge water tank for storing water supplied to the water vapor generation means, and is supplied by the purge water supply means at the time of shutdown processing of the fuel cell system Water vapor is generated from water by the water vapor generating means, and the fuel cell system is purged with the generated water vapor.

  The fuel cell system according to the second aspect of the present invention includes a purge water supply path that supplies and stores water to a purge water tank, and a purge water amount that is connected to the purge water supply path and adjusts the amount of water stored in the purge water tank. Adjusting means and temperature measuring means for measuring the temperature of the water vapor generating means, and operating the purge water amount adjusting means according to the temperature of the water vapor generating means measured by the temperature measuring means during operation of the fuel cell system. The amount of water stored in the purge water tank is changed, and purging is performed by the amount of water stored in the purge water tank during the operation stop processing of the fuel cell system.

  In the fuel cell system of the third aspect of the present invention, the purge water supply means stops supplying water when energized and supplies water when de-energized.

  According to a fourth aspect of the present invention, there is provided a fuel cell system comprising fuel generating means for reforming a raw material and steam to generate a fuel gas containing hydrogen, wherein the steam generating means is the fuel generating means. To do.

  The fuel cell system according to a fifth aspect of the present invention includes a pressurizing unit capable of pressurizing water stored in a purge water tank and supplying the water to the water vapor generating unit.

  The fuel cell system of the present invention can easily perform a purge operation without using an inert gas such as nitrogen, and can supply electric power from the outside to the fuel cell system not only during a normal shutdown process but also during a power failure. Even when the supply is interrupted, the fuel cell system can be purged and stopped safely. As a result, it is not necessary to separately install an inert gas supply means inside and outside the fuel cell system, and the installation space, initial cost and running cost of the fuel cell system can be reduced.

  In addition, by using fuel generation means as water vapor generation means, it is not necessary to add extra energy to generate water vapor, and energy can be used efficiently even during stop processing, reducing energy consumption It becomes possible to do.

  Further, by changing the amount of purge water supplied in accordance with the temperature of the fuel generating means, it is possible to prevent water from accumulating without evaporating inside the fuel generating means. As a result, corrosion of the fuel generating means can be prevented and normal operation can be performed without causing water clogging at the next startup.

  Further, by supplying water to the fuel generating means by pressurizing by the pressurizing means, even when the pressure of the fuel gas path in the fuel cell system including the fuel generating means, the fuel supply path, and the fuel cell is high, the fuel Purge can be performed without increasing the size of the battery system.

  Hereinafter, embodiments of the present invention will be described with reference to FIGS.

(Embodiment 1)
FIG. 1 is a configuration diagram showing a fuel cell system according to a first embodiment of the present invention. The fuel cell system according to Embodiment 1 includes a fuel cell 11 that generates electric power using a supplied fuel gas containing hydrogen and an oxidant gas such as air, and an oxidant supply path 12 that supplies the oxidant gas. A fuel supply path 13 for supplying fuel gas, a steam generation means 14 connected to the fuel supply path 13 upstream of the fuel cell 11, a purge water path 15 for supplying water to the steam generation means 14, A purge water tank 16 for storing water and a purge water supply means 17 for supplying water to the steam generation means 14 are constituted by a shut-off valve that closes the valve when energized and opens the valve when not energized.

  The operation of the first embodiment configured as described above will be described.

  During system operation, the fuel cell 11 generates power using the oxidant gas supplied through the oxidant supply path 12 and the fuel gas supplied through the fuel supply path 13. During normal operation stop processing, the purge water supply means 17 is opened, and the water stored in the purge water tank 16 is supplied to the steam generation means 14. The water vapor generation means 14 generates water vapor by heating the supplied water, and supplies the water vapor to the connected fuel supply path 13 to thereby provide a fuel cell system including the fuel supply path 13, the fuel cell 11 and the like. The operation is stopped by purging the fuel gas on the fuel gas path with water vapor.

  Further, at the time of a power failure, when power supply from the outside is interrupted to the fuel cell system, the shut-off valve of the purge water supply means 17 is opened accordingly, and water is supplied to the steam generation means 14. The water supplied by the residual heat of the steam generation means 14 evaporates, and the residual fuel gas on the fuel gas path in the fuel cell system including the fuel supply path 13 and the fuel cell 11 is purged with the steam safely. Can be stopped.

  According to the configuration of the fuel cell system in the first embodiment, a purge operation without using an inert gas such as nitrogen can be easily performed, and the fuel cell system is externally connected not only during a normal shutdown process but also during a power failure. Even when the supply of electric power from is interrupted, the fuel cell system can be purged and stopped safely. Therefore, it is not necessary to separately install an inert gas supply means inside and outside the fuel cell system, and the installation space, initial cost and running cost of the fuel cell system can be reduced.

  Although the above description has been made using a shut-off valve as the purge water supply means 17, the purge water supply means 17 is not limited to the shut-off valve, and has a similar closing function and supply function other than the valve. The same effect can be obtained for the above.

(Embodiment 2)
FIG. 2 is a configuration diagram showing a fuel cell system according to the second embodiment of the present invention. Constituent elements that are the same as those in the first embodiment are given the same reference numerals, and descriptions thereof are omitted. The fuel cell system according to the second embodiment includes a fuel generation unit 22 that generates fuel gas, a temperature measurement unit 18 that measures the temperature of the fuel generation unit 22, and a purge water supply that supplies and stores water in the purge water tank 16. It comprises a path 19, a pump as purge water amount adjusting means 20 connected to the purge water supply path 19, and a control means 21.

  The operation of the second embodiment configured as described above will be described.

  During system operation, the fuel generation means 22 heats a raw material such as natural gas supplied from the outside in an atmosphere including water vapor to generate a fuel gas including hydrogen, and supplies the fuel cell 11 with the fuel gas. The fuel cell 11 generates power using the oxidant gas supplied through the oxidant supply path 12 and the fuel gas supplied through the fuel supply path 13. Depending on the temperature T of the fuel generating means 22 measured by the temperature measuring means 18, the control means 21 operates the purge water amount adjusting means 20 to supply and store the water quantity Q in the purge water tank 16.

Water Q, the fuel generating section 22 and the fuel supply path 13, a maximum of volume Q _S of the fuel gas passage in the fuel cell system including the fuel cell 11 is determined as follows by the control unit 21. Assuming that the temperature T, specific heat C, weight M, purge water temperature _TW , boiling point T _V , specific heat C _L , and latent heat of vaporization C _G of the fuel generating means 22, the water amount Q is expressed by the following equation (Equation 1). .

  During the operation stop process, the purge water supply means 17 is opened, and the water stored in the purge water tank 16 is supplied to the fuel generation means 22. The fuel generating means 22 generates water vapor by heating the supplied water, and supplies water vapor to the connected fuel supply path 13, so that the fuel gas on the fuel gas path in the fuel cell system is vaporized. Purge to stop operation.

With the configuration of the fuel cell system according to the second embodiment, it is necessary to add extra energy to generate water vapor by using the fuel generation means 22 as the water vapor generation means 14 together with the effects described in the first embodiment. In addition, since energy can be efficiently used even during the stop process, energy consumption can be reduced. Further, by changing the amount of purge water supplied in accordance with the temperature of the fuel generating means 22, it is possible to prevent water from accumulating without evaporating inside the fuel generating means 22. Therefore, corrosion of the fuel generating means 22 can be prevented and normal operation can be performed without causing water clogging at the next start-up.

  Although the above description has been made using a shut-off valve as the purge water supply means 17, the purge water supply means 17 is not limited to the shut-off valve, and has a similar closing function and supply function other than the valve. The same effect can be obtained for the above.

  Further, the above description has been made using a pump as the purge water amount adjusting means 20, but the same effect can be obtained with a configuration in which the amount of water is measured from the water level in the purge water tank 16 and the opening and closing of the valve is controlled. .

Strictly speaking it is desirable to measure the temperature T _W of the purge water, the same effect can be obtained when substituting the representative temperature.

(Embodiment 3)
The components of the fuel cell system according to the third embodiment of the present invention are shown in FIG. 2 which is the same as that of the second embodiment, and the same components are given the same reference numerals and the description thereof is omitted. The purge water tank 16 according to the third embodiment has a structure for pressurizing the stored water and supplying it to the fuel generating means 22 as the pressurizing means. Shown in The inside of the purge water tank 16 is divided up and down by a partition plate 23 that can move freely while being sealed, and a spring 24 is connected to the top plate and the partition plate 23 of the purge water tank 16.

  The operation of the third embodiment configured as described above will be described.

  During the operation of the system, the fuel generation means 22 generates a fuel gas containing hydrogen by heating a raw material such as natural gas supplied from the outside in an atmosphere containing water vapor, and supplies it to the fuel cell 11. The fuel cell 11 generates power using the oxidant gas supplied from the oxidant supply path 12 and the fuel gas supplied from the fuel supply path 13. Depending on the temperature T of the fuel generating means 22 measured by the temperature measuring means 18, the control means 21 operates the purge water amount adjusting means 20 to supply and store the water quantity Q in the purge water tank 16. The water supplied to the purge water tank 16 pushes up the partition plate 23 and stores a force in the spring 24.

Water Q, the fuel generating section 22 and the fuel supply path 13, a maximum of volume Q _S of the fuel gas passage in the fuel cell system including the fuel cell 11 is determined as follows by the control unit 21. Temperature T, specific heat C of the fuel generating section 22, and weight M, the temperature _{T W} and the boiling point _{T V} purge water, specific heat _{C L,} when the latent heat of vaporization _{C G,} water Q is similar second embodiment, equation (1 ).

  During the operation stop process, the purge water supply means 17 is opened, and the water stored in the purge water tank 16 is supplied to the fuel generation means 22. At that time, the partition plate 23 is pushed down by the force stored in the spring 24, whereby water is pressurized and supplied to the fuel generating means 22. The fuel generating means 22 generates water vapor by heating the supplied water, and supplies water vapor to the connected fuel supply path 13, so that the fuel gas on the fuel gas path in the fuel cell system is vaporized. Purge to stop operation.

  According to the configuration of the fuel cell system in the third embodiment, in addition to the effects described in the second embodiment, the fuel generation unit 22 and the fuel supply path are supplied by supplying water to the fuel generation unit 22 by being pressurized by the pressurization unit. 13. Even when the pressure of the fuel gas path in the fuel cell system including the fuel cell 11 is high, purging can be performed without increasing the size of the fuel cell system.

  Although the above description has been made using the spring 24 as the pressurizing means, the gas spring in which the sealed space is filled with gas, the volume expansion container in which the purge water tank 16 itself has a balloon-like structure, and the like. The same effect can be obtained.

  Although the above description has been made using a shutoff valve as the purge water supply means 17, the purge water supply means 17 is not limited to the shutoff valve, and has a similar closing function and supply function other than the valve. The same effect can be obtained for the above.

  Further, the same effect can be obtained with a configuration in which a pump operating by a backup power source such as various secondary batteries, capacitors, and dry batteries is used as the purge water supply means 17 and the pump is a pressurizing means.

  Further, the above description has been made using a pump as the purge water amount adjusting means 20, but the same effect can be obtained with a configuration in which the amount of water is measured from the water level in the purge water tank 16 and the opening and closing of the valve is controlled. .

Strictly speaking it is desirable to measure the temperature T _W of the purge water, the same effect can be obtained when substituting the representative temperature.

  The fuel cell system according to the present invention has an effect that it can be safely stopped by purging the fuel in the fuel path of the fuel cell even when the external power supply is interrupted, such as during a power failure. In addition, it is useful as a fuel cell system for home use, car use, and portable equipment.

The block diagram of the fuel cell system by the 1st Embodiment of this invention Configuration diagram of a fuel cell system according to a second embodiment of the present invention Configuration diagram of a purge water tank according to a third embodiment of the present invention Configuration diagram of conventional fuel cell system

Explanation of symbols

DESCRIPTION OF SYMBOLS 11 Fuel cell 12 Oxidant supply path 13 Fuel supply path 14 Steam generation means 15 Purge water path 16 Purge water tank 17 Purge water supply means 18 Temperature measurement means 19 Purge water supply path 20 Purge water amount adjustment means 21 Control means 22 Fuel generation means 23 Partition plate 24 Spring 25 Water vapor supply means 26 Air supply means

Claims (5)

A fuel cell that generates power using fuel and an oxidant; an oxidant supply path that supplies oxidant to the fuel cell; a fuel supply path that supplies fuel to the fuel cell; and the fuel supply upstream of the fuel cell. A steam generation means connected to the path, a purge water path connected to the steam generation means for supplying water, a purge water supply means for supplying water to the steam generation means in the purge water path, and the steam generation And a purge water tank for storing water to be supplied to the fuel cell. Water is generated by the steam generator from water supplied by the purge water supply during the operation stop process of the fuel cell system, and fuel is generated by the generated steam. A fuel cell system for purging a battery system. A purge water supply path for supplying water to the purge water tank, a purge water amount adjusting means connected to the purge water supply path for adjusting the amount of water stored in the purge water tank, and a temperature measurement for measuring the temperature of the water vapor generating means And operating the purge water amount adjusting means in accordance with the temperature of the water vapor generating means measured by the temperature measuring means during operation of the fuel cell system to change the amount of water stored in the purge water tank. The purging is performed by the amount of water stored in the purge water tank at the time of stopping the operation of the fuel cell system.
The fuel cell system according to claim 1. The purge water supply means has a function of stopping supply of water when energized and supplying water when de-energized,
The fuel cell system according to claim 1 or 2. Comprising fuel generating means for reforming the raw material and steam to generate fuel gas containing hydrogen, wherein the steam generating means is the fuel generating means,
The fuel cell system according to any one of claims 1 to 3. Pressurizing the water stored in the purge water tank, characterized by comprising a pressurizing means capable of supplying the water vapor generating means,
The fuel cell system according to any one of claims 1 to 4.

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