JPH06105622B2 - Fuel cell power generation system and operating method thereof - Google Patents

Description

TECHNICAL FIELD OF THE INVENTION The present invention relates to a fuel cell power generation system and an operating method thereof.

[Technical Background of the Invention and Problems Thereof] Conventionally, a fuel cell is known as a device that directly converts the energy of a fuel into electrical energy. In this fuel cell, usually, a pair of porous electrodes of a fuel electrode and an oxidizer electrode are arranged with an electrolyte layer sandwiched between them, fuel such as hydrogen is brought into contact with the back surface of the fuel electrode, and air, etc. is contacted with the back surface of the oxidizer electrode. It is designed to generate electricity by contacting the oxidant of the above and reacting them electrochemically, and it can extract electric energy with high conversion efficiency as long as the above fuel and oxidant are supplied. is there. Although there are various types of fuel cells of this type, a phosphoric acid type fuel cell using a phosphoric acid electrolyte as an electrolyte will be described below.

A fuel cell of this type usually has a reformer for obtaining hydrogen gas as a fuel used for power generation in the fuel cell, and often constitutes the entire fuel cell power generation system. That is, a mixed gas of a hydrocarbon gas or an oxygen-containing hydrocarbon gas such as alcohol (hereinafter collectively referred to as a hydrocarbon-based gas) and steam is introduced into a reformer, and the reformer reforms the hydrocarbon-based gas. The gas is steam reformed to generate reformed gas, and this reformed gas is converted to hydrogen gas through various equipment systems such as a shift converter, and this hydrogen gas is introduced into the fuel cell as its fuel, which is then supplied to air and electricity. The chemical reaction is performed to generate power, and the generated power is supplied to an external load.

By the way, in the fuel cell power generation system having such a configuration, when the load demand on the fuel cell is rapidly increased, the mixed gas amount to be introduced into the reformer is increased in order to cope with the sudden load increase. It is necessary to increase the amount of power generated by the fuel cell. However, in this case, the rise time of the generated power is delayed by the time constant of the system until the amount of power generated by the fuel cell actually increases after the amount of mixed gas introduced into the reformer increases. Therefore, there is a problem that it is not possible to instantaneously follow a rapid increase in load. Therefore, in order to cope with such a rapid increase in load of electric power demand, it is necessary to make the system as compact as possible and minimize the time constant of the system. However, in the conventional fuel cell power generation system described above, From the viewpoint of the function of each component, it is impossible to reduce the time constant below a certain limit value.

[Object of the Invention] The present invention has been made in order to solve the above problems, and an object thereof is to instantaneously follow a rapid load increase and supply power stably to the load. Fuel cell power generation system and its operating method.

[Summary of the Invention] In order to achieve the above object, firstly, in the first invention,
A reformer that introduces a mixed gas of hydrocarbon-based gas and steam and a heating gas to steam-reform the hydrocarbon-based gas to generate reformed gas, and the reformed gas generated by the reformer The fuel cell is introduced as fuel, and the fuel is electrochemically reacted with air to generate electricity, and the fuel cell that supplies the generated power to the load and the surplus generated power from the fuel cell are stored as heat to store the heat. A preheating medium for preheating a mixed gas of a hydrocarbon-based gas and steam by a heat storage medium, or a heat storage device for supplying to a heating gas, and is provided between the output side of the fuel cell and the heat storage device, and is provided for the fuel cell. And a switch for electrically disconnecting the heat accumulator from the fuel cell when the load demand rapidly increases.

In the second invention, a reformer for introducing a mixed gas of a hydrocarbon-based gas and steam and a heating gas to steam-reform the hydrocarbon-based gas to generate a reformed gas, and a reformer. The reformed gas generated in 1. is introduced as fuel, the fuel is electrochemically reacted with air to generate electricity, and the fuel cell that supplies this generated power to the load and the surplus generated power from the fuel cell A heat storage unit that stores heat as heat, and supplies the heat to a preheating medium for preheating a mixed gas of a hydrocarbon-based gas and steam, or a heating gas.
In the operating method of the fuel cell power generation system, which is provided between the output side of the fuel cell and the heat accumulator and comprises a switch that electrically connects the fuel cell and the heat accumulator, in the normal operation, the load on the fuel cell is The fuel cell generates more power than the load required, and the switch is closed to store the excess generated power as heat in the regenerator.When the load demand on the fuel cell rapidly increases, the switch is opened. The regenerator is electrically separated from the fuel cell.

[Embodiment of the Invention] An embodiment of the present invention will be described below with reference to the drawings.

FIG. 1 is a block diagram showing a configuration example of a fuel cell power generation system according to the present invention. In FIG. 1, 1
Is a preheater for introducing a mixed gas 2 of a hydrocarbon-based gas such as methane gas and steam, and preheating this with a preheating medium 3 to near the steam reforming temperature, 4 is a heating gas 5, and the above preheater 1 A reformer for introducing a heated mixed gas 6 of hydrocarbon-based gas and steam, and steam-reforming the hydrocarbon-based gas to generate reformed gas, 7 is generated by the reformer 4. The reformed gas 8 is introduced, and the reformed gas 8
It is a system of various devices including a shift converter for removing carbon monoxide to obtain a hydrogen-rich gas. Further, 9 is hydrogen gas obtained through the above various equipment systems 7.
A fuel cell in which 10 is introduced as a fuel, and the fuel is electrochemically reacted with air supplied from an air supply device (not shown) to generate power, and the generated power is supplied to an external load 11
I am trying to supply it to. On the other hand, 12 is the fuel cell 9
Is a heat accumulator provided on the output side of the battery so that it can be electrically connected and disconnected via a switch 13, and the surplus generated power from the fuel cell 9 is directly converted into heat as a heating power source, and the heat is stored in the heat storage medium 14 Thus, the heat is supplied to a necessary heat supply section in the system, for example, the above-mentioned preheating medium 3 or heating gas 5.
In addition, 15 is an auxiliary heating source for heating the heat storage medium 14, which is used as necessary.

In the fuel cell power generation system configured as described above, the mixed gas 2 of hydrocarbon-based gas and steam is preheated in the preheater 1 by the preheating medium 3 to a temperature near the steam reforming temperature, and the hydrocarbon-based gas and steam heated by this are heated. The mixed gas 6 is introduced into the reformer 4. In this reformer 4, the hydrocarbon-based gas is steam-reformed to produce reformed gas, and the reformed gas 8 produced in this reformer 4 becomes hydrogen gas 10 through various equipment systems 7 and is used as fuel. It is introduced into the fuel cell 9. Then, the hydrogen gas 7 introduced into the fuel cell 9
Generates an electric power by electrochemically reacting with the air supplied from an air supply device (not shown), and the generated electric power is supplied to the load side.

That is, specifically describing the operating method, first, in normal times, the fuel cell 9 generates power at a load amount equal to or greater than the maximum load request amount for the fuel cell 9, and the surplus generated power is converted into heat to the heat accumulator 12. Convert and store heat. In other words, if the external load 11 is 50% load,
If the reformer 4 is operated with a load of 75%, 25% of the electric power will be surplus. Then, at this time, the switch 13 is closed to supply the surplus electric power to the heat storage device 12, which is converted into heat and the heat storage medium 14
The surplus electric power is consumed by supplying it to the preheating medium 3 or the heating gas 5 via.

Next, when the maximum load demand on the fuel cell 9 is rapidly increasing from such a state, the switch 13 is opened to electrically disconnect the heat accumulator 12 from the fuel cell 9. In other words, if the external load 11 rapidly increases from 50% load amount to 75% load amount, the switch 13 is opened and the heat storage unit 12 is opened.
By electrically disconnecting the fuel cell 9 from the fuel cell 9,
Supply all power to 12 to load 11. As a result, all of the electric power supplied to the heat storage device 12 during the normal operation is instantaneously supplied to the external load 11. In this case,
After opening the switch 13, the system is in thermal balance by supplementing the amount supplied to the heat accumulator 12 with the auxiliary heating source 15.

As described above, in the present embodiment, the reformer 4 that introduces the mixed gas 6 of the hydrocarbon-based gas and the steam preheated in the preheater 1 and steam-reforms the hydrocarbon-based gas to generate the reformed gas. And various equipment systems 7 for obtaining hydrogen gas from the reformed gas 8 produced by the reformer 4 and hydrogen gas 10 from the various equipment systems 7 are introduced as fuels, and the hydrogen gas 10 is supplied to air and electricity. A fuel cell 9 that chemically reacts to generate electric power and supplies the generated electric power to an external load 11 is provided so as to be electrically contactable and separable through the fuel cell 9 and a switch 13. When a fuel cell power generation system is configured with a regenerator 12 capable of storing the excess generated power from the battery 9 as heat, and when the fuel cell power generation system is operated, a load commensurate with the maximum load request amount for the fuel cell 9 is normally provided. Generate more than the required amount of electricity with the fuel cell 9. The surplus generated electric power is stored as heat in the heat storage device 12 via the switch device 13, and the switch device 13 is opened to open the heat storage device 12 when the load demand on the fuel cell 9 rapidly increases.
Is electrically disconnected from the fuel cell 9, and the regenerator is stored during normal operation.
The electric power that has been supplied to 12 is supplied to the load 11.

Therefore, a part of the stored heat can be used by supplying it to the preheating medium for preheating the mixed gas of the hydrocarbon-based gas and steam introduced into the fuel cell, or the heating gas, Not only can power be stably supplied to the load 11 by instantaneously following a rapid increase in load during normal operation, but the surplus power during normal operation is not affected in the power supply to the load 11. By storing the heat in the heat storage device 12 as heat, it is possible to effectively use the surplus power during normal operation to achieve heat balance of the entire fuel cell power generation system and improve thermal efficiency. Furthermore, by appropriately selecting the capacity of the heat accumulator 12, it is possible to cope with a large change in the load fluctuation range of the external demand power.
By appropriately selecting the heat storage medium 14, it is possible to use the heat energy at a higher temperature, so that it is possible to increase the utility value of the heat energy.

Next, another embodiment of the present invention will be described with reference to the drawings.

FIG. 2 is a block diagram showing another configuration example of the fuel cell power generation system according to the present invention. The same parts as those in FIG. 1 are designated by the same reference numerals, and the description thereof will be omitted. Only the part will be described. In FIG. 2, a compressor 16 is driven by a motor 17 and pressurizes a part of the hydrogen gas 10 supplied to the fuel cell 9 in FIG. 1 to a predetermined pressure,
Reference numeral 18 is a hydrogen gas storage tank for storing the hydrogen gas pressurized by the compressor 16, and the stored hydrogen gas is a pressure reducing valve.
It can be supplied to the fuel cell 9 via 19. The above-mentioned motor 17 is connected to the output side of the fuel cell 9 via the switch 20. That is, in the present embodiment, in order to cope with the rapid increase in the load demand on the fuel cell 9 described above, the facility for storing hydrogen gas in a pressurized state and supplying it to the fuel cell 9 as necessary is described above. This is provided in addition to the heat storage device 12 described above.

That is, in such a fuel cell power generation system, if the external load 11 is 50% load and the reformer 4 is operated with a load of 100%, 50% of the power becomes surplus. Then, at this time, the switch 13 is closed to supply the surplus electric power to the heat storage device 12, which is converted into heat and supplied to the preheating medium 3 or the heating gas 5 via the heat storage medium 14 to generate the surplus power. It consumes 25% of the electric power which is half of.
Further, the switch 20 is closed to supply surplus electric power to the motor 17, which drives the compressor 16 to introduce a part of the hydrogen gas 10 into the fuel cell 9 and pressurizes the hydrogen gas 10 to store the hydrogen gas. Storage in the tank 18 consumes 25% of the electric power, which is the other half of the surplus electric power.

Next, if the load demand on the fuel cell 9 increases rapidly from such a state, the switch 13 is opened to electrically disconnect the heat accumulator 12 from the fuel cell 9. That is, if the external load 11 rapidly increases from 50% load amount to 75% load amount, the switch 13 is opened to electrically disconnect the heat storage device 12 from the fuel cell 9, To regenerator 12
Supply 25% of all power to load 11. If the external load 11 rapidly increases from 50% load to 100% load, the switch 13 is opened and the regenerator 12 is connected to the fuel cell 9
Is electrically disconnected from the load 11 to supply 25% of electric power to the heat accumulator 12 to the load 11. At the same time, 75%
In order to cope with a change in the load amount from the load amount to 100%, the switch 20 is opened to electrically disconnect the motor 17 from the fuel cell 9, so that 25% of the electric power to the motor 17 is entirely transferred to the load 11. Supply. As a result, all of the electric power supplied to the heat storage device 12 and the motor 17 during normal operation is instantaneously supplied to the external load 11.

In this case, the hydrogen gas commensurate with the compression power used as the drive source of the motor 17 should be left in balance. That is, the reformer 4 is producing the reformed gas for that amount. Therefore, in this case, the reformer 4 balances by reducing the load amount of the extra reformed gas generation portion. Further, when there is an external load demand of 25% or more consumed by the motor 17, pressurized hydrogen gas stored in the hydrogen gas storage tank 18 is supplied to the fuel cell 9 by opening the pressure reducing valve 19. As a result, it is possible to cope with a rapid increase in load.

The embodiment of FIG. 2 has been described assuming that the external load 11 rapidly increases from the 50% load amount to the 100% load amount, or the load further increases from the 100% load amount. However, these load amounts can be freely changed according to the capacity of the heat storage system and the capacity of the hydrogen gas storage system, and this does not change the gist of the present invention.

In addition, the present invention can be variously modified and implemented within the scope of the invention.

As described above, according to the present invention, a mixed gas of a hydrocarbon-based gas and steam and a heating gas are introduced, and the hydrocarbon-based gas is steam-reformed to generate a reformed gas. The reformer and the reformed gas produced by the reformer are introduced as fuel,
This fuel electrochemically reacts with air to generate electricity, and the fuel cell that supplies this generated power to the load and the surplus generated power from the fuel cell are stored as heat, and the heat is carbonized by the heat storage medium. It is installed between the output side of the fuel cell and the regenerator, which is the preheating medium for preheating the mixed gas of hydrogen-based gas and steam, or the regenerator that supplies the heating gas, and the load demand on the fuel cell increases rapidly. Then, a fuel cell power generation system is configured with a switch that electrically disconnects the heat storage device from the fuel cell, and when operating the fuel cell power generation system, at a normal time, a load amount equal to or greater than the load demand amount for the fuel cell is set. Power is generated by the fuel cell, the switch is closed and the surplus generated power is stored as heat in the heat accumulator.When the load demand on the fuel cell increases rapidly, the switch is opened and the heat accumulator is switched to the fuel cell. It is possible to supply power stably to the load by instantaneously following a rapid load increase, and to store excess surplus power generated during normal operation as heat. It is possible to provide a highly reliable fuel cell power generation system that can be effectively used and improve the thermal efficiency of the entire system, and an operating method thereof.

[Brief description of drawings]

FIG. 1 is a configuration block diagram showing an embodiment of the present invention, and FIG.
The figure is a block diagram showing the configuration of another embodiment of the present invention. 1 ... Preheater, 2 ... Mixed gas of hydrocarbon gas and steam, 4 ... Reformer, 7 ... Various equipment systems, 8 ... Reformed gas, 9
… Fuel cell, 10… Hydrogen gas, 11… Load, 12… Heat storage, 1
3, 20 ... Switch, 16 ... Compressor, 17 ... Motor, 18 ... Hydrogen gas storage tank, 19 ... Reducing valve.

Claims (2)

[Claims] 1. A reformer for introducing a mixed gas of a hydrocarbon-based gas and steam and a heating gas to steam-reform the hydrocarbon-based gas to generate a reformed gas, and a reformer for generating the reformed gas. Introduced reformed gas as fuel,
The fuel is electrochemically reacted with air to generate electricity, and a fuel cell that supplies the generated power to a load, and the surplus generated power from the fuel cell is stored as heat, and the heat is stored by a heat storage medium. A preheating medium for preheating the mixed gas of the hydrocarbon-based gas and steam, or a regenerator to be supplied to the heating gas, and provided between the output side of the fuel cell and the regenerator,
A fuel cell power generation system, comprising: a switch that electrically disconnects the heat storage device from the fuel cell when the load demand on the fuel cell rapidly increases. 2. A reformer for introducing a mixed gas of a hydrocarbon-based gas and steam and a heating gas to steam-reform the hydrocarbon-based gas to generate a reformed gas, and a reformer for generating the reformed gas. The generated reformed gas is introduced as a fuel, the fuel is electrochemically reacted with air to generate electricity, and the generated electric power is supplied to the load, and the surplus generated electric power from the fuel cell is heated. As a heat storage medium, a heat storage medium for preheating a mixed gas of the hydrocarbon-based gas and steam, or a heat storage device for supplying the heating gas to the output side of the fuel cell and the heat storage unit. In a method of operating a fuel cell power generation system, which is provided between the fuel cell and a switch for electrically connecting the fuel cell and a heat storage device, in a normal operation, a load requirement for the fuel cell is satisfied. Over load Power generation is performed by a fuel cell, the switch is closed and the surplus generated power is stored as heat in the heat accumulator, and when the load demand on the fuel cell rapidly increases, the switch is opened to operate the heat accumulator as fuel. A method for operating a fuel cell power generation system, which is characterized in that it is electrically disconnected from a battery.