JPH09115537A - Fuel cell power-generation system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a fuel cell power-generation system without the output reduction of a fuel cell in the case of an electric output fluctuation and fuel switching. SOLUTION: This system consists of a reformer 2 which reforms the fossil fuel to produce hydrogen, a fuel cell 3 which generates electricity using hydrogen from the reformer 2 and oxygen in the air as a fuel, and an electric power conversion device 9 which converts the generated power of the fuel cell 3. In this system, a hydrogen supply device 100 which supplies hydrogen together with the hydrogen from the reformer 2 to the fuel cell 3 or an oxygen supply device 200 which supplies oxygen together with the oxygen 7 in the air to the fuel cell 3 is provided, and the hydrogen in the hydrogen supply device 100 or the oxygen in the oxygen supply device 200 is supplied to the fuel cell 3 according to the output power fluctuation of the power conversion device 9.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention comprises a reformer for reforming fossil fuel into hydrogen, a fuel cell for generating electric power using hydrogen and oxygen as fuel, and an electric output system for converting electric power generated by the fuel cell. Fuel cell power generation system.

[0002]

2. Description of the Related Art A conventional fuel cell power generation system is shown in FIG.
As shown in, a fuel such as city gas is used as the regular fuel 1. The fuel cell 3 is composed of a fuel electrode 4, an electrolyte 5, and an air electrode 6. By supplying hydrogen to the fuel electrode 4 and oxygen 7 in the air to the air electrode 6, a DC power 8 is generated by a cell reaction.
Get. The obtained DC power 8 is supplied to the power converter 9 and used as an electric output. In order to produce hydrogen to be supplied to the fuel electrode 4, the city gas, which is the regular fuel 1, is reformed by the reformer 2 to be a reformed gas containing a large amount of hydrogen. This reformed gas is supplied to the fuel electrode 4 of the fuel cell 3 so that oxygen in the air 7
Is supplied to the air electrode 6, the fuel cell 3 generates electricity.
In order to increase (or decrease) the generated power of the fuel cell 3, the generated power 8 is changed by increasing (or decreasing) the amounts of the common fuel 1 such as city gas and the oxygen 7 in the air.

In the conventional fuel cell power generation system shown in FIG. 4,
Although city gas is used as the regular fuel 1, it cannot generate power when the supply of city gas is interrupted. Therefore, in order to apply the fuel cell power generation system to a system that requires high reliability such as a communication power supply system. As shown in FIG. 5, when the reserve gas 1'such as propane is stored and the city gas runs out, the fuel switching device 10 is used to switch to the reserve fuel 1'such as propane to continue power generation. Fuel cell power generation systems have been proposed. In the system of FIG. 5,
Propane, which is the reserve fuel 1 ', is supplied to the reformer 2 to produce hydrogen. In this case, since the reforming conditions are different from the case of city gas, a predetermined reforming temperature, fuel supply amount and steam It is necessary to control the supply amount. In this way, even when the supply of the city gas of the regular fuel 1 is interrupted, it is possible to continue the power generation of the fuel cell by switching to the reserve fuel 1 ′ and generating hydrogen in the reformer.

[0004]

In the above-described conventional fuel cell power generation system, when the electric output is rapidly taken out from the fuel cell, there is a time delay in producing hydrogen corresponding to the electric output in the reformer. There was a problem that the output of the fuel cell was temporarily reduced due to the insufficient supply of hydrogen and the fuel cell was deteriorated. Therefore, it was not possible to supply electric power from the fuel cell to a load with a large fluctuation in electric output.

Further, when the fuel is switched from city gas, which is a regular fuel, to propane, which is a preliminary fuel, reforming conditions are different even if the same reformer is used, so that hydrogen can be stably taken out from the reformer. There is a time delay until the steady state is reached. Therefore, when the fuel is switched, a shortage of hydrogen as a fuel occurs, and the output of the fuel cell temporarily decreases. Sudden deterioration of the fuel cell occurs if a constant electric output is continuously taken out with the fuel cell output decreasing,
There was a problem that the fuel cell system went down. Therefore, in order to apply the fuel cell power generation system as a power supply that requires high reliability, such as a power supply for communication, there is a possibility that the system will go down during fuel switching.

FIG. 6 shows the changes over time in the hydrogen supply amount and the fuel cell output voltage when the electric output changes in the prior art.
It can be easily understood that the hydrogen supply amount is insufficient and the fuel cell output voltage is reduced during the Δt1 hour when the electric output changes. Further, FIG. 7 shows a time change of the hydrogen supply amount and the fuel cell output at the time of fuel switching of the above-mentioned conventional technique.
It can be easily understood that when the fuel is switched, the hydrogen supply amount is insufficient for Δt2 hours and the fuel cell voltage is reduced accordingly.

The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a fuel cell power generation system in which the fuel cell output does not decrease when the electric output changes or when the fuel is switched.

[0008]

The solution to the above problems can be achieved by the present invention having the following novel characteristic configurations. That is, the first feature of the present invention is a reformer that reforms fossil fuel to produce hydrogen, and a fuel cell that generates electricity using hydrogen from the reformer and oxygen in the air as fuel.
And a fuel cell power generation system including an electric output system for converting generated power of the fuel cell, in combination with hydrogen from the reformer and hydrogen supply device for supplying hydrogen to the fuel cell or oxygen in the air An oxygen supply device for supplying oxygen to the fuel cell is provided, and hydrogen of the hydrogen supply device or oxygen of the oxygen supply device is supplied in accordance with power fluctuation of the electric output system.

A second feature of the present invention is a reformer for reforming fossil fuel to produce hydrogen, a fuel cell for generating electricity using hydrogen from the reformer and oxygen in the air as fuel, and In a fuel cell power generation system including an electric output system that converts generated power of a fuel cell, a fuel switching device that switches between a regular fuel and a backup fuel to supply the reformer and hydrogen from the reformer are combined. A hydrogen supply device for supplying hydrogen to the fuel cell or an oxygen supply device for supplying oxygen to the fuel cell together with oxygen in the air is provided, and when the fuel is switched by the fuel switching device, the hydrogen of the hydrogen supply device or the To supply oxygen from the oxygen supply device.

A third feature of the present invention is that the fuel cell power generation system according to the first feature or the second feature includes a high-pressure tank for storing hydrogen or oxygen generated by electrolysis of water. The oxygen is supplied to the fuel cell together with hydrogen from the reformer or oxygen in the air.

A fourth feature of the present invention is that the fuel cell power generation system according to the third feature includes a thermoelectric element for generating power by exhaust heat of the fuel cell, and electrolyzes water by the power generated by the thermoelectric element. That is.

Since the present invention has the above-mentioned structure, when the fuel is switched, the hydrogen or oxygen stored in the hydrogen supply device or the oxygen supply device is combined with the hydrogen from the reformer or the oxygen in the air. By supplying, it is possible to prevent deterioration of the fuel cell and realize a highly reliable fuel cell power generation system.

By storing hydrogen and oxygen generated by electrolysis of water in a high-pressure tank, hydrogen and oxygen in the high-pressure tank can be supplied when the electric output of the fuel cell fluctuates greatly. Can be prevented from deteriorating. Furthermore, a highly efficient fuel cell power generation system can be realized by obtaining the electric power required for the electrolysis of water from the thermoelectric element using the exhaust heat of the fuel cell.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiments of the present invention will be described below in detail with reference to the drawings. Needless to say, various changes and improvements can be made without departing from the spirit of the present invention.

FIG. 1 is a structural explanatory view showing a fuel cell power generation system according to a first embodiment of the present invention. In the figure, 1 is a regular fuel, 2 is a reformer, 3 is a fuel cell, 4 is a fuel electrode, 5 is an electrolyte, 6 is an air electrode, 7 is oxygen, 8 is direct current power, 9 is a power converter, and 100 is A hydrogen supply device, 110 is a hydrogen tank, 120 is a valve, 200 is an oxygen supply device, 210 is an oxygen tank, and 220 is a valve.

That is, the fossil fuel common fuel 1 is reformed by the reformer 2 to produce hydrogen, and the hydrogen from the reformer 2 is supplied to the fuel electrode 4 of the fuel cell 3 and the hydrogen supply device 10 is supplied.
Hydrogen from 0 is supplied to the fuel electrode 4 of the fuel cell 3. Further, oxygen 7 in the air is supplied to the air electrode 6 of the fuel cell 3, and oxygen from the oxygen supply device 200 is supplied to the air electrode 6 of the fuel cell 3. The fuel cell 3 includes hydrogen from the reformer 2 and the hydrogen supply device 100 and oxygen 7 in the air and the oxygen supply device 2.
Direct current power 8 is generated by a cell reaction of the electrolyte 5 using oxygen from 00 as fuel. The DC power 8 from the fuel cell 3 is supplied to the power converter 9 and used as an electric output. The valve 120 of the hydrogen supply device 100 is controlled to supply hydrogen from the hydrogen tank 110, or the valve 2 of the oxygen supply device 200 is controlled according to the power fluctuation of the electric output system.
20 is controlled to supply oxygen from the oxygen tank 210.

A fuel cell power generation system may be configured to include only one of the hydrogen supply device 100 and the oxygen supply device 200. FIG. 2 shows the configuration of a fuel cell power generation system showing a second embodiment of the present invention. FIG. 2 shows a hydrogen supply device 100 that supplies hydrogen in parallel with a line that supplies a reformed gas containing a large amount of hydrogen to a fuel electrode 4 of a fuel cell power generation system of the fuel cell power generation system in FIG. It is characterized by being provided. Further, an oxygen supply device 200 for supplying oxygen is provided in parallel with a line for supplying oxygen 7 in the air to the air electrode 6 of the fuel cell 3. Note that, of the symbols shown in FIG. 2, the same symbols as those in FIG.

In the hydrogen supply device 100, hydrogen having a high pressure is stored in the hydrogen tank 110 for storing hydrogen, and the valve 120 is adjusted when the fuel is switched when the required amount of hydrogen in the fuel cell 3 is insufficient. Hydrogen is supplied to the fuel electrode 4 of the fuel cell 3 together with the reformed gas. The timing for adjusting the valve 120 is to supply hydrogen from the hydrogen tank 110 before the fuel is switched in advance by using the switching signal of the fuel switching device 10 that switches between the regular fuel 1 and the auxiliary fuel 1 ′, so that there is no shortage of hydrogen. . Even if a large amount of hydrogen is supplied to the fuel electrode 4, surplus hydrogen that has not been used in the cell reaction flows out from the outlet of the fuel electrode 4. In order to effectively utilize the surplus hydrogen, it may be used as the fuel gas of the reformer 2 for securing the heat quantity necessary for the reforming reaction.

On the other hand, oxygen is required for the cell reaction of the fuel cell 3 in addition to hydrogen, but if oxygen in the air electrode 6 is insufficient, the output characteristics of the fuel cell 3 will deteriorate and deteriorate. In order to withstand a sudden change in electric output, it is necessary to quickly supply hydrogen and oxygen to the fuel electrode 4 and the air electrode 6 of the fuel cell 3. Therefore, in addition to supplying hydrogen to the fuel electrode 4, not only oxygen 7 in the air but also the oxygen tank 21 of the oxygen supply device 200 is supplied to the air electrode 6.
By supplying oxygen from 0 by adjusting the valve 220, it is possible to provide a fuel cell power generation system in which the output characteristic of the fuel cell 3 is not significantly deteriorated even when the electric output is rapidly taken out from the fuel cell 3.

Since the time required for the fuel to switch from the regular fuel 1 to the backup fuel 1'and stabilize is relatively short, the amount of hydrogen and oxygen that is insufficient at the time of fuel switching is stored in the tank and is insufficient. You can deal with it by switching from time to time. On the other hand, when attempting to make the fuel cell 3 respond to fluctuations in the output power of the fuel cell 3, the replacement of the hydrogen tank 110 and the oxygen tank 210 is frequently repeated, so that it is necessary to constantly produce hydrogen and oxygen.

FIG. 3 shows a third embodiment of the present invention.
This is a configuration for always storing hydrogen and oxygen in the hydrogen tank 110 and the oxygen tank 210 of FIG. High pressure tank 30
In this method, water is stored in 0 and hydrogen and oxygen are produced by electrolysis of water by the electrodes of the positive electrode 310 and the negative electrode 320. Hydrogen storage unit 330 of high-pressure tank 300
The oxygen storage unit 340 is partitioned by a partition wall 350 so that electricity can flow but gas cannot move. Since hydrogen gas and oxygen gas obtained by electrolysis of water are stored in the hydrogen storage unit 330 and the oxygen storage unit 340 in the high-pressure tank 300, the valves 360 and 370 are adjusted to rapidly change the fuel cell 3. Sufficient hydrogen and oxygen can be supplied to the fuel cell 3 even with fluctuations. The water consumed by electrolysis needs to be replenished from the outside, but make-up water 380 for this is supplied.
For this, general tap water may be used, but water vapor discharged from the fuel cell 3 by the cell reaction may be condensed and used. At this time, since tap water contains a large amount of impurities, it is generally supplied after being filtered with an ion exchange resin or the like to remove the impurities.

As a method of supplying electric power to the electrodes 310 and 320 of the high-pressure tank 300, there is a method of utilizing the electric output of the fuel cell 3. In FIG. 3, the exhaust heat obtained from the fuel cell 3 is used as the thermoelectric element 400. It shows a method of electrolyzing water by using it for power generation. Since the reformer 2 is maintained at a high temperature for reforming the fossil fuel into hydrogen, the thermoelectric element 400 is used according to the temperature difference between the high temperature of the reformer 2 and the room temperature, and the obtained electric power is used to generate water. Used for electrolysis of.
The power conversion circuit 500 adjusts the power supplied from the thermoelectric element 400 according to the amount of hydrogen or oxygen generated by electrolysis of water. Thus, there is an advantage that the pressure in the high-pressure tank 300 can be controlled to be constant by adjusting the power supplied from the thermoelectric element 400 by the power conversion circuit 500. With this configuration, hydrogen and oxygen can be stored in the high-pressure tank 300 at a high pressure, so that the valves 360, 3
By adjusting 70, the required amount of hydrogen and oxygen can be supplied when needed. Here, an example in which high concentration hydrogen or oxygen is used only when the electric output fluctuates or when the fuel is switched has been described. However, by constantly using these hydrogen and oxygen for the power generation of the fuel cell 3, highly efficient fuel cell power generation can be achieved. It goes without saying that you can do it. In the present embodiment example, the reformer 2
The example in which the electric power generated by the thermoelectric element 400 that utilizes the difference between the high temperature and the room temperature of is used for the electrolysis of water was described
A thermoelectric element may be attached to a place other than the reformer 2 where electric power required for electrolyzing water is obtained. It goes without saying that hydrogen or oxygen may be generated by electrolyzing water using something other than a thermoelectric element.

[0023]

As described above, according to the present invention, hydrogen and oxygen stored at a high pressure are rapidly supplied at the time of fuel switching from city gas to propane or when the electric output of the fuel cell fluctuates. Since a sufficient amount of fuel can be supplied to the fuel electrode and the air electrode of the fuel cell, it is possible to realize a highly reliable fuel cell power generation system that can prevent deterioration of the fuel cell and can also be applied as a communication power source. A highly efficient fuel cell power generation system can be realized by using the exhaust heat of the fuel cell to generate hydrogen and oxygen.

[Brief description of the drawings]

FIG. 1 is a configuration explanatory view showing a first embodiment of the present invention.

FIG. 2 is a configuration explanatory view showing a second embodiment example of the present invention.

FIG. 3 is a configuration explanatory view showing a third embodiment example of the present invention.

FIG. 4 is a structural explanatory view showing an example of a conventional fuel cell power generation system.

FIG. 5 is a configuration explanatory view showing another example of a conventional fuel cell power generation system.

FIG. 6 is a waveform diagram showing an example of waveforms at various portions when a fuel cell electric output varies in a conventional fuel cell power generation system.

FIG. 7 is a waveform diagram showing an example of waveforms of various parts when switching fuels in a conventional fuel cell power generation system.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Regular fuel, 1 '... Reserve fuel, 2 ... Reformer, 3 ... Fuel cell, 4 ... Fuel electrode, 5 ... Electrolyte, 6 ... Air electrode, 7 ... Oxygen, 8 ... DC power, 9 ... Power converter 10 ... Fuel switching device, 100 ... Hydrogen supply device, 110 ... Hydrogen tank, 1
20 ... Valve, 200 ... Oxygen supply device, 210 ... Oxygen tank, 220 ... Valve, 300 ... High pressure tank, 310 ... Positive electrode,
320 ... Negative electrode, 330 ... Hydrogen storage section, 340 ... Oxygen storage section, 350 ... Partition wall, 360, 370 ... Valve, 380 ... Make-up water, 400 ... Thermoelectric element, 500 ... Power conversion circuit.

Claims (4)

[Claims] 1. A reformer that reforms fossil fuel to produce hydrogen, a fuel cell that generates electricity using hydrogen from the reformer and oxygen in the air as fuel, and power generated by the fuel cell is converted. And a hydrogen supply device for supplying hydrogen to the fuel cell together with hydrogen from the reformer or an oxygen supply for supplying oxygen to the fuel cell together with oxygen in the air. A fuel cell power generation system, comprising a device, and supplying hydrogen of the hydrogen supply device or oxygen of the oxygen supply device according to power fluctuations of the electric output system. 2. A reformer for reforming fossil fuel to produce hydrogen, a fuel cell for generating electricity using hydrogen from the reformer and oxygen in the air as fuel, and converting generated power of the fuel cell. In a fuel cell power generation system including an electric output system for supplying electricity, hydrogen is supplied to a fuel cell together with a fuel switching device that switches between a regular fuel and a backup fuel to supply to the reformer, and hydrogen from the reformer. A hydrogen supply device or an oxygen supply device that supplies oxygen to the fuel cell together with oxygen in the air, and supplies hydrogen of the hydrogen supply device or oxygen of the oxygen supply device when performing fuel switching by the fuel switching device. A fuel cell power generation system characterized by: 3. A high-pressure tank is used as a hydrogen supply device for supplying hydrogen and an oxygen supply device for supplying oxygen, and the hydrogen or the oxygen is obtained by electrolysis of water in the high-pressure tank. The fuel cell power generation system according to 1 or 2. 4. The fuel cell power generation system according to claim 3, further comprising a thermoelectric element that generates electric power by exhaust heat of the fuel cell, and electrolysis of water is performed by electric power generated by the thermoelectric element.