JPH08180897A - Fuel cell generating plant - Google Patents

Abstract

PURPOSE: To provide a fuel cell generating plant in which the operation can be continued without changing the operating temperature of a fuel cell body even when the steam supply to a steam utilizing system is stopped by failure and the capacity of a heat exchanger can be minimized. CONSTITUTION: This fuel cell generating plant has a fuel cell body cooling system for circulating a cooling water for cooling the reaction heating in a fuel cell body 1 through a steam separator 2 and a means 8 for supplying the steam generated in the steam separator 2 to a steam utilizing system. It also has a steam treatment device 9 capable of taking out the steam in the steam separator 2 independently from the fuel cell body cooling system and the steam utilizing system, so that the excessive steam of the steam separator 2 can be taken out by the steam treatment device 9 when the steam supply to the steam utilizing system is stopped. When the temperature of the fuel cell body is lowered by the stop, the steam of the steam separator 2 is discharged to the steam treatment device 9 to enhance the heat exchanging ratio.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a fuel cell power plant comprising a fuel cell main body, a fuel cell main body cooling system, and means for supplying steam to a steam utilization system.

[0002]

2. Description of the Related Art In recent years, fuel cell power plants, which have been put into practical use, directly convert the energy of fuel such as hydrogen into electrical energy by an electrochemical reaction occurring in the fuel cell body. As long as the oxidant is supplied to the fuel cell main body, it has an advantage that electric energy can be extracted with high conversion efficiency.

In this type of fuel cell power plant, hydrogen gas as a fuel for a fuel cell is produced by steam reforming a hydrocarbon-based raw material gas such as methane and supplied to the fuel electrode of the fuel cell body. . Air is supplied as an oxidant to the oxidant electrode of the fuel cell body.

Since the fuel cell main body generates reaction heat during an electrochemical reaction, a fuel cell main body cooling system is provided for cooling this heat generation and always maintaining the fuel cell main body at an appropriate operating temperature. The fuel cell body cooling system is often equipped with a brackish water separator that generates steam necessary for steam reforming of fuel.

Furthermore, fuel cell power plants can supply not only electrical energy but also thermal energy. This heat energy is often recovered in the form of steam or hot water by a brackish water separator or a heat energy recovery device such as a steam generator or a heat exchanger installed in the plant, and is used for cooling and heating.

FIG. 2 shows an example of a fuel cell main body cooling system and a thermal energy supply means in a conventional fuel cell power generation plant. 1 is a fuel cell main body,
The fuel cell main body cooling system is composed of a brackish water separator 2, a circulation pump 3, and a heat exchanger 4, and constitutes one circulation system. Further, the inlet temperature of the battery body 1 is detected by the temperature detector 7, and the amount of heat exchanged by the heat exchanger 4 communicating with the cooling fluid 6 is adjusted by the control valve 5 to control the set value based on the load and the battery current. are doing. Furthermore, the thermal energy supplies the steam generated in the brackish water separator 2 to the steam utilization system via the control valve 8.

[0007]

The conventional system shown in FIG. 2 in which the fuel cell main body cooling system and the thermal energy supply means of the fuel cell power plant have the following problems to be solved. When it is necessary to stop the steam supply due to an accident in the steam utilizing system while the fuel cell power plant is operating while supplying the steam to the steam utilizing system, the control valve 8 is closed. Therefore, the energy in the cooling water system of the fuel cell main body becomes excessive. The inlet temperature of the battery main body 1 is controlled to the same temperature level as when steam is supplied by the control valve 5, while the outlet temperature of the battery main body 1 becomes higher than that when steam is supplied.

Generally, the operating temperature of the battery main body 1 is often determined from the life and performance, and it is not preferable that the operating temperature changes depending on the presence or absence of the steam supply. Therefore, the present invention has been proposed in order to solve the above-mentioned problems of the conventional technology, and its purpose is to change the operating temperature of the fuel cell main body even when the steam supply to the steam utilization system is stopped. It is to provide a fuel cell power generation plant of a steam extraction type that can be continuously operated without being operated.

When the temperature of the fuel cell body 1 is stopped and the temperature is lowered,
The control valve 8 is closed and the steam supply to the steam utilization system is stopped. Also, while the circulation pump 3 is operating, the control valve 5
Changes to the closing direction (the direction in which the amount of inflow to the heat exchanger 4 increases) so that the temperature of the fuel cell main body 1 is lowered according to a preset set value. The flow of the fluid at the time of cooling is as shown by a in FIG.

Therefore, the temperature of the fuel cell main body 1 is lowered only by the heat exchanger 4, and the temperature lowering time varies depending on the capacity of the heat exchanger 4. That is, when the heat exchanger 4 has a large capacity (when the cooling capacity is large), the temperature lowering time becomes faster,
If the capacity is small (the cooling capacity is small), the cooling time will be delayed.

Although commercialization of fuel cell power generation plants has been promoted in recent years, there still remain problems such as cost reduction and compactness. Therefore, from the viewpoint of simplifying the system, for example, devices are deleted, combined, and downsized. In the conventional apparatus shown in FIG. 2, for example, miniaturizing the heat exchanger 4 is also one method. However, as described above, downsizing the heat exchanger 4 leads to delaying the temperature lowering time of the fuel cell body 1.

Therefore, the present invention has been proposed in order to solve the problems of the prior art as described above, and its purpose is to:
It is an object of the present invention to provide a steam extraction type fuel cell power plant in which a heat exchanger used for lowering the temperature of a fuel cell main body can be downsized.

[0013]

[MEANS FOR SOLVING THE PROBLEMS] A fuel cell main body, a cooling water inlet pipe and an outlet pipe connected to the fuel cell main body, a cooling water circulation pump, and a brackish water separator are provided, and cooling water is cooled from the brackish water separator. A cooling system for the fuel cell main unit that forms a circulation system that uses a water circulation pump to supply the fuel cell main unit through the cooling water inlet pipe and returns the waste cooling water from the fuel cell main unit to the brackish water separator through the cooling water outlet pipe. And a means for supplying the steam generated in the brackish water separator to the steam utilization system, the steam treatment for processing the steam generated in the brackish water separator inside the fuel cell power plant. A fuel cell power plant having an apparatus and a control means for adjusting the amount of fluid flowing into or out of the steam processing apparatus.

[0014]

When the supply of steam to the steam utilization system is stopped, surplus steam is processed by the steam processing device inside the fuel cell power plant. When the supply of steam to the steam utilization system is stopped, this surplus steam is supplied to the steam treatment device, so there is no excess energy in the cooling water system of the fuel cell main unit, and the steam supply to the steam utilization system is prevented. The operating temperature of the fuel cell body will not change depending on the presence or absence of the fuel cell.

Further, since the steam generated in the brackish water separator is supplied to the steam treatment device when the temperature of the fuel cell main body is stopped and the temperature is reduced, the heat exchanger used for lowering the temperature of the fuel cell main body is small. Can be converted.

[0016]

FIG. 1 is a diagram showing a first embodiment of the present invention.
Since the same parts as those of the conventional example shown in FIG. 2 are designated by the same reference numerals, the description thereof will be omitted. In this embodiment, a steam treatment device 9 and a control valve 10 are newly provided, and when the steam supply to the steam utilization system is stopped, the steam generated in the brackish water separator 2 is supplied to the steam treatment device 9. is there. Here, the steam processing device 9 is, for example, a condenser that heat-exchanges the steam flowing into the cooling fluid 11 to condense the steam.

Next, the operation of this embodiment will be described. When steam is being supplied to the steam utilization system, the control valve 8 is open and the control valve 10 is closed. Here, when it is necessary to stop the steam supply due to an accident in the steam utilization system, for example, the control valve 8 is closed and the control valve 10 is opened at the same time. As a result, the steam that has been supplied to the steam utilization system will flow into the steam treatment device 9, and the water that has been condensed there into supercooled water will be recovered by the water treatment system in the fuel cell power plant. To be done. Therefore, unlike the conventional example shown in FIG. 2, energy does not become excessive in the cooling water system of the fuel cell main body, and the operating temperature of the fuel cell main body remains constant regardless of whether steam is supplied to the steam utilization system. can do.

As described above, in this embodiment, when the supply of steam to the steam utilization system is stopped, surplus steam is supplied to the newly provided steam processing device, so that excess energy in the fuel cell main body cooling water system is not generated. It is possible to prevent life and performance deterioration due to changes in the operating temperature of the fuel cell body without occurring.

Next, the operation according to claim 4 will be described. The control valve 8 is open and the control valve 10 is closed when the fuel cell body 1 is in a power generating state and steam is being supplied to the steam utilization system.

When the plant stop command is given, the fuel cell main body 1 stops power generation and lowers the temperature.
The control valve 8 is closed and the steam supply to the steam utilization system is stopped. Further, while the circulation pump 3 is in operation, the control valve 5 is closed (increases the amount of inflow into the heat exchanger 4) so that the temperature of the fuel cell body 1 is lowered according to a preset value. Direction).

At the same time, the control valve 10 is opened and the steam generated in the brackish water separator 2 is discharged to the steam treatment device 9 to lower the pressure (temperature) of the brackish water separator 2. That is, there are two fluid flows, a and b in FIG.

As described above, in this embodiment, since the temperature of the fuel cell body 1 is stopped and lowered by the two devices, the heat exchanger 4 and the steam processing device 9, the capacity of the heat exchanger 4 is increased as compared with the conventional one. Can be reduced.

[0023]

As described above, according to the present invention, when the supply of steam to the steam utilization system is stopped, the surplus steam of the cooling water system for the fuel cell main body is supplied to the steam processing apparatus, so that the cooling of the fuel cell main body is performed. It is possible to prevent life and performance deterioration due to changes in operating temperature of the fuel cell body without causing excess energy in the water system.

Further, when the temperature of the fuel cell main body is stopped and the temperature is stopped, the stop temperature is also applied to the steam treatment device 9, so that the capacity of the heat exchanger can be reduced and a compact fuel cell power plant is provided. be able to.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment of a fuel cell power plant according to the present invention.

FIG. 2 is a configuration diagram of a conventional fuel cell power generation plant.

[Explanation of symbols]

1 ... Battery main body, 2 ... Brackish water separator, 3 ... Circulation pump, 4 ...
Heat exchangers, 5, 8, 10 ... Control valves, 6, 11 ... Cooling fluid, 7 ... Temperature detector, 9 ... Steam processing device (condenser).

Claims (4)

[Claims] 1. A fuel cell main body for generating electricity by an electrochemical reaction between a fuel and an oxidant, and a fuel for circulating cooling water for cooling reaction heat generation in the fuel cell main body through a brackish water separator and a circulation pump. A battery body cooling system, a means for supplying steam generated in the steam water separator to a steam utilization system, and a steam generated in the steam water separator can be taken out separately from the fuel cell body cooling system and the steam utilization system. A fuel cell power plant comprising a steam processing device. 2. The fuel cell power generation system according to claim 1, further comprising adjusting means for supplying the steam of the brackish water separator to the steam processing device when the supply of steam to the steam utilization system is stopped. plant. 3. The fuel cell power plant according to claim 1, wherein the steam processing device is a condenser that heat-exchanges inflowing steam to condense the steam. 4. The fuel cell power plant according to claim 1, further comprising adjusting means for supplying the steam of the brackish water separator to the steam processing device when the temperature of the fuel cell main body is stopped and cooled.