JPH0782870B2 - Fuel cell cooling water system - Google Patents

Description

Description: TECHNICAL FIELD OF THE INVENTION The present invention relates to a fuel cell in which a cell reaction temperature is cooled with water, and more particularly to a fuel cell cooling water system capable of achieving a long life.

[Technical background of the invention and its problems]

In recent years, the practical application of fuel cells has attracted great expectations as a power generator with few pollution factors and high energy conversion efficiency, and the development of fuel cells by the public and private sectors has been strongly promoted. In this fuel cell, usually, a pair of porous electrodes are arranged with an electrolyte-impregnated matrix sandwiched between them, a fuel such as hydrogen is brought into contact with the back surface of one electrode, and an oxidant such as oxygen is attached to the back surface of the other electrode. Are brought into contact with each other, and the electrochemical reaction that takes place at this time is utilized to extract the electric energy from between the electrodes. As long as the fuel and the oxidant are supplied, the electric energy is taken out with a high conversion efficiency. Is something that can be done.

There are a water cooling method and an air cooling method as cooling methods for heat generated in the fuel cell during power generation. FIG. 8 is a flow chart showing a cell cooling water system of a fuel cell plant.
The battery cooling water system consists of the fuel cell body 1, the steam separator 2,
Cooling water circulation pump 3, water storage tank 4, water treatment device 5,
It comprises a shutoff valve 6, a shutoff valve 7, a drain valve 8 and an insulating tube 9 described later. The cooling water circulates in the water / water separator 2, the cooling water circulation pump 3, the fuel cell body 1, and the cooling water loop connecting the water / water separator 2. A part of the cooling water is sent to the water treatment device 5 through the water storage tank 4 to improve the water quality, and then returns to the cooling water loop again.

The water cooling system has a feature that the cooling water system is compact and waste heat can be easily used, but it also has the following problems peculiar to fuel cells. FIG. 9 is a perspective view showing a structural example of the fuel cell body 1. In FIG. 9, a cooling plate 11 is inserted for every several 10 unit cells of the fuel cell.
A thin cooling pipe 12 is embedded in the cooling plate 11. Since there is a potential difference between the cooling plates 11 due to the cells 10 stacked in series, they are electrically insulated by the insulating tube 9. FIG. 10 is a sectional view showing details around the insulating tube 9. Since there is a potential difference between the insulating joints 13 on both ends of the insulating tube 9, electrolytic corrosion due to leak current occurs. If the cooling water contains metal ions, such as iron ions or copper ions, of several tens of PPB or more, the metal compound adheres to the insulating joint 13, and the deposit 14 clogging the flow path of the cooling water to cause clogging. . This clogging gradually progresses, the flow rate of the cooling water gradually decreases, and the battery is not cooled sufficiently. When the power generation is further continued, the battery temperature gradually rises, and eventually the battery temperature cannot be controlled.
When the battery temperature rises, the battery catalyst deteriorates, the battery life is shortened due to evaporation of the battery electrolyte, and the electrode burns out due to the crossover of fuel and air, making it impossible to generate electricity.

In order to prevent such clogging, the battery cooling water is required to have a high water quality with an electric conductivity of 0.4 μ / cm or less and a turbidity of 10 PPB or less. There is also a demand for an effective method of removing clogging that gradually progresses.

[Object of the Invention]

The present invention has been made to solve the above problems, and an object thereof is to extend the life of a fuel cell and a power generation facility by removing the above-mentioned deposits and preventing clogging of a cell cooling pipe. It is to provide a fuel cell cooling water system capable of improving reliability as a fuel cell.

[Outline of Invention]

In order to achieve the above object, the fuel cell cooling water system of the present invention enables the fuel cell main body to be cut off from other devices by installing a flange so that a blind plate is inserted upstream and downstream of the fuel cell main body. It is characterized in that a chemical cleaning device and a flange for connection are installed on the side of the fuel cell main body so that the fuel cell main body can be easily chemically cleaned.

Example of Invention

An embodiment of the present invention will be described in detail below with reference to the drawings.

FIG. 1 is a flow chart showing a battery cooling water system applied to the present invention. In the figure, the first flange 16 (hereinafter,
The flange 16), the second flange 18 (hereinafter simply referred to as the flange 18), the first blind plate 17 (hereinafter simply referred to as the blind plate 17), the second blind plate 19 (hereinafter simply referred to as the blind plate 19) ) Is piping and equipment newly installed for the battery cooling water system in FIG.

FIG. 2 shows the flow of cooling water of the battery cooling water system during normal power generation. Blind plate on flange 16 in the figure
Instead of 17, a first spacer 20 is inserted so that cooling water can flow. The cooling water flows through the fuel cell body 1 from the bottom to the top of the figure. A part of the cooling water is sent to the water treatment device 5 through the water storage tank 4 to improve the water quality, and then returns to the cooling water loop again.

FIG. 3 is an example showing the flow of cooling water when the fuel cell main body 1 is chemically cleaned when power generation is stopped. In the figure flange
In place of the blind plate 19, the second spacer 21 is contained in 18 so that the chemical cleaning agent can flow. The chemical cleaning device includes a chemical cleaning agent tank 22, a chemical cleaning pump 23, shutoff valves 24, 25,
26,27 and bypass lines 28,29. By opening the shutoff valves 26 and 27 and closing the shutoff valves 24 and 25 as shown in FIG. 3, the chemical cleaning agent flows through the fuel cell main body 1 in the same direction as during normal power generation.

In Fig. 4, the shut-off valves 24 and 25 are opened and the shut-off valves 26 and 27 are closed. The chemical cleaning agent is the fuel cell body 1 from the top to the bottom of the figure.
That is, it flows in the direction of backwashing the battery cooling pipe 12 in FIG.

The deposit 14 shown in FIG. 10 will be described below based on an experiment conducted on the clogging of the fuel cell cooling pipe. First, the adhesion force of the adhering matter 14 is weaker toward the tip of the adhering matter 14, and when the force is applied by the flow of the cooling water, the periphery of the adhering matter 14 is separated. Secondly, the shape of the deposit 14 is related to the flow direction of the cooling water. Figure 10 shows the case where the cooling water flows from the left to the right in the figure.The upstream side has a gentle slope, while the downstream side from the tip has a steep slope and is perpendicular to the flow direction of the cooling water. near. Therefore, the force applied to the deposit 14 differs depending on the flow direction of the cooling water, and in FIG. 10, the deposit 14 flows more from the right to the left than when the cooling water flows from the left to the right.
The force applied to is increased. Therefore, it was found that the flow was reversed, that is, backwashing removed all or part of the deposit 14.

In the battery cooling water system of the present invention, the plant is stopped after generating power for a certain period of time, and the cooling pipe 12 of the battery is alternately changed in direction of the flow of the chemical cleaning agent as shown in FIGS. 3 and 4. The deposit 14 is effectively removed by the chemical cleaning by using. Thereafter, by periodically performing chemical cleaning of the battery cooling water system, the clogging due to the deposit 14 can be prevented for a long period of time.

Further, the deposit 15 shown in FIG. 10 is a corrosion product or the like broken down by electrolytic corrosion. When the cooling water flows from left to right in the figure, it is piled up at the place where the cooling water tends to stay, as shown in Fig. 10. If the deposit 15 is deposited on the insulating tube 9, the insulation may deteriorate. This problem also causes the sediment 15 to be lifted up by the above-mentioned backwashing and removed from the insulating tube 9 portion to prevent insulation deterioration.

Incidentally, the present invention is not limited to the above-mentioned embodiment, and for example, by adding a third flange 30 and a blind plate 31 as shown in FIG. 5, chemicals similar to those in FIGS. 3 and 4 can be obtained. The cooling water loop can be chemically cleaned by connecting a cleaning device and bypassing the fuel cell body 1. It is effective to carry out this chemical cleaning at the start-up after construction of the plant and after construction of the battery cooling water system. Further, as shown in FIG. 6, by adding a shutoff valve 32 in front of the flange 18,
It is possible to connect to the chemical cleaning device without draining the cooling water in the fuel cell body 1. FIG. 7 also shows a flange as in FIG.
The shutoff valves 32 and 33 are added to 18,30 and it is possible to continue with the chemical cleaning device without draining the battery cooling water.

〔The invention's effect〕

As described above, according to the present invention, the cell cooling water system and the chemical cleaning device can be easily connected, and the chemical cleaning is performed while backwashing or normal cleaning the fuel cell body, so that the deposits on the cell cooling pipe are effectively removed. It becomes possible and can prevent clogging. Further, at the time of start-up after the construction of the plant or after the construction of the battery cooling water system, the battery cooling water system can be chemically cleaned without shutting off the water of low quality from the fuel cell main body by cutting it off from the fuel cell main body. In addition, backwashing removes deposits that may be deposited on the insulating tube and cause insulation deterioration, thus preventing insulation deterioration.

Therefore, the fuel cell cooling system of the present invention can prevent clogging of the cell cooling pipes, prolong the life of the fuel cell and improve the reliability of the power generation equipment.

[Brief description of drawings]

FIG. 1 is a flow chart showing an embodiment of the present invention, FIG. 2 is a flow chart showing the flow direction of cell cooling water at the time of power generation, and FIGS. 3 and 4 are fuel cell main bodies connected to a chemical cleaning device. FIG. 5, FIG. 6, FIG. 6 and FIG. 7 are flow charts showing another embodiment of the present invention during chemical cleaning, and FIG. 8 is a flow showing a cell cooling water system of a conventional fuel cell plant. Figure, No. 9
FIG. 10 is a perspective view showing one structural example of the fuel cell main body, and FIG. 10 is a sectional view showing details around the insulating tube. 1 ... Fuel cell main body, 2 ... Steam separator 3 ... Cooling water circulation pump, 4 ... Water storage tank 5 ... Water treatment device, 6 ... Shut-off valve 7 ... Shut-off valve, 8 ... Drain valve 9 ... Insulation tube, 10 ... Single cell 11 ... Cooling plate, 12 ... Cooling tube 13 ... Insulation joint, 14 ... Adhesion 15 ... Deposit, 16 ... Flange 17 ... Blind plate, 18 …… Flange 19 …… Blank plate, 20 …… Spacer 21 …… Spacer, 22 …… Chemical cleaning agent tank 23 …… Chemical cleaning pump, 24 …… Cutoff valve 25 …… Cutoff valve, 26 …… Cutoff valve 27 …… … Shut-off valve, 28… Bypass line 29… Bypass line, 30… Flange 31… Blind plate, 32… Valve 33… Valve

Claims (2)

[Claims] 1. A cooling pipe formed on a cooling plate of a fuel cell main body, a cooling water loop connected to the cooling pipe via an insulating tube for circulating cooling water to the cooling pipe, and the cooling water loop. A water-water separator provided in the cooling pipe for separating gas contained in the cooling water, and a circulating water pump provided in the cooling water loop for circulating the cooling water in the cooling water loop via the cooling pipe. And a water treatment loop that sends a part of the cooling water to a water treatment device through a water storage tank to improve the water quality and then returns the water treatment loop to the cooling water loop. A first flange provided in the cooling water loop between the container and the fuel cell main body and between the circulating water pump and the fuel cell main body, and between the first flange and the fuel cell main body Of the cooling water Second flange connected to a chemical cleaning device for branching the chemical cleaning agent between the normal cleaning direction and the reverse cleaning direction, and the first flange during normal power generation of the fuel cell main body. And a first spacer for connecting the cooling water loop to each other and a first blind plate for disconnecting the cooling water loop connected to the first flange during chemical cleaning of the fuel cell body. A second blind plate that is connected to the second flange to shut off the cooling water loop during normal power generation of the fuel cell main body; and a second blind plate during chemical cleaning of the fuel cell main body.
And a second spacer connected to the flange for communicating the cooling water loop with each other. 2. A cooling pipe formed on a cooling plate of a fuel cell main body, a cooling water loop connected to the cooling pipe via an insulating tube for circulating cooling water to the cooling pipe, and the cooling water loop. A water-water separator provided in the cooling pipe for separating gas contained in the cooling water, and a circulating water pump provided in the cooling water loop for circulating the cooling water in the cooling water loop via the cooling pipe. And a water treatment loop that sends a part of the cooling water to a water treatment device through a water storage tank to improve the water quality and then returns the water treatment loop to the cooling water loop. A first flange provided in the cooling water loop between the container and the fuel cell main body and between the circulating water pump and the fuel cell main body, and between the first flange and the fuel cell main body Of the cooling water Second flange connected to a chemical cleaning device for branching the chemical cleaning agent between the normal cleaning direction and the reverse cleaning direction, and the first flange during normal power generation of the fuel cell main body. And a first spacer for connecting the cooling water loop to each other and a first blind plate for disconnecting the cooling water loop connected to the first flange during chemical cleaning of the fuel cell body. A second blind plate that is connected to the second flange to shut off the cooling water loop during normal power generation of the fuel cell main body; and a second blind plate during chemical cleaning of the fuel cell main body.
A second spacer connected to the flange for communicating the cooling water loop, and a second spacer provided on the fuel cell body side of the second flange and a second blind plate for connecting work. A fuel cell cooling water system, comprising: a shutoff valve that is closed at the time.