JPS60227362A - Method of supplying electrolyte in matrix-type fuel cell - Google Patents

Abstract

PURPOSE:To prevent any formation of a liquid path of electrolyte during the suspension of battery operation by filling electrolyte paths with electrolyte so as to supply electrolyte into the matrix layer and by feeding a gas through the electrolyte paths so as to evaporate and remove electrolyte adhering to the walls of the electrolyte paths. CONSTITUTION:After a bulb 15b is closed and valves 13a and 13b are opened, blind plugs 71c and 72c are attached to the openings 71b and 72b of electolyte paths 71 and 72. Next, after electrolyte in an electrolyte tank 14 is filled into electrolyte paths 71 and 72 by opening a valve 12a, electrolyte is supplied from a supply path 8 into a matrix layer 1 through supply holes 8a. After the supply of electrolyte is completed, the valve 12a is closed and blind plugs 71c and 72c are removed to discharge surplus electrolyte through openings 71b and 72b. Next, after the bulb 15b is opened, moistended gas is sent into electrolyte paths 71 and 72 through bulbs 13a and 13b by means of blower 15a before being exhausted through openings 71b and 72b, thereby evaporating and removing electrolyte adhering to the walls of the paths 71 and 72.

Description

[Detailed Description of the Invention] [Technical Field to Which the Invention Pertains] The present invention provides a method for applying electrolyte to the matrix layer of a cell stack through an electrolyte passage provided in the stacking direction of a cell stack formed by stacking cell cells. Concerning how to replenish electrolytes.

[Prior art and its problems]

FIG. 1 is an exploded perspective view showing an example of a unit cell of a matrix type fuel cell. VC#i fuel electrodes 2 and oxidizer electrodes 3 are disposed on both sides of the matrix layer 1, and a porous lip-attached electrode base material 4 having grooves 4a provided in the direction of arrow A on the outside thereof and perpendicular to the grooves 4a. A porous lip-attached electrode base material 5 having a structure 5a provided in the direction of the electrode is provided to constitute a unit cell. A gas non-diffusible separation plate 6 is interposed between the single cells to separate the reaction gas, and a large number of these cells are stacked to form a cell stack. Then, the fuel gas as a reaction gas flows in the direction of arrow A, and the oxidant gas flows in the direction of arrow B, respectively, into the grooves 4a and 5a of the electrode base materials 4 and 5 with lips, and are supplied to each electrode to generate electricity. Occur.

However, as the operating time of the fuel cell increases, the electrolyte evaporates and scatters, so it is necessary to replenish the electrolyte after a certain operating time.

For this reason, conventionally, the operation of the battery is temporarily stopped and an electrolyte passage provided penetrating in the stacking direction of a cell stack formed by stacking unit cells is filled with electrolyte, and multiple branches are formed from this replenishment passage. It is known that electrolyte is replenished into the matrix layer of a unit cell through a communication path, and after replenishment, the excess electrolyte is discharged through the replenishment path to operate the battery again.
There is a problem in that the electrolyte supplied to the supply passage adheres to the inner wall of the passage, and this adhered electrolyte causes a liquid junction. In particular, the electrolyte that has been concentrated due to the scattering of water does not easily separate from the inner wall of the passage, and in practical use, it has been desired to improve this problem.

[Purpose of the invention]

The present invention has been made in view of the above, and an object of the present invention is to provide an electrolyte replenishment method that does not cause a liquid junction due to the electrolyte.

[Summary of the invention]

According to the present invention, the above object is a method of replenishing electrolyte to the M+Jx layer of a stacked cell through an electrolyte passage provided penetrating in the stacking direction of a cell stack formed by stacking cell stacks. When the battery is out of operation, the electrolyte passageway is filled with electrolyte to replenish the electrolyte to the matrix layer, and after the remaining electrolyte is discharged from the electrolyte passageway, gas is caused to flow through the electrolyte passageway to form a gas on the passageway wall. This is achieved by removing the attached electrolyte by transpiration.

[Embodiments of the invention]

The present invention will be described in detail below based on the drawings.

FIG. 2 is a system diagram showing a replenishment method according to an embodiment of the present invention, and FIG. 3 is a diagram of the replenishment structure in FIG.
A fuel electrode 2 and an oxidizer electrode 3 are arranged on both sides of the matrix layer 1, and a sealing material 9 is provided around the periphery thereof. Furthermore, on the outside thereof, there is a groove 4a that serves as a passage for fuel gas.
(see FIG. 1), a porous lip-attached electrode base material 4;
A porous lip-attached electrode base material 5 having a groove 5a through which an oxidant gas flows, which is provided in a direction perpendicular to the groove 4a, is in close contact with the fuel electrode 2 and the oxidizer electrode 3, respectively. A gas non-diffusible separate plate 6 for separating reaction gas is interposed between the cells, a large number of these are stacked, and a cooling plate 10 is interposed between each of these cells to form a cell stack.

An electrolyte replenishment path 8 is provided in the electrode base material 4 with a lip, and is communicated with the electrolyte replenishment channel 8 through a matrix layer IK replenishment hole 8a. And the cell stack manifold 20.

Electrolyte passage 71 at a location outside of 20a (see Figure 3).

72 is provided in the direction of the cell stack, and the upper cooling plate 1
Open lower lower 1a, 72a on the side of 0, lower cooling plate t.

Open lower lower parts 1b and 72b are provided on the side surface of 8a. Note that the opening may be located at an end plate provided in place of the cooling plate, depending on the case. These electrolyte passages 71 and 72 communicate with the electrolyte supply passage 8.

An electrolyte tank 11 filled with electrolyte is provided above the cell stack, and an outlet pipe 12 is connected to the pulp 12.
It is connected to the conduit 13 via a.

And a pipe line 16 provided with pulps 13a and 13b, respectively.
.

17 is an electrolyte passage 71.7 via the open lower lower parts 1a and 72a.
Connected to 2. - The gas supply pipe 14 is connected to the blower 14a in the upper space 15c of the sealed water tank 15 into which the power water is injected.
The glass filter 14b is inserted into the water by penetrating the side wall of the water tank 15 through the glass filter 14b.

A pipe connected to the upper space 15c of the water tank 15 is connected to the pipe line 13 via a blower 15a and pulp 15b that send humidified gas to the electrolyte passages 71, 72.

Now, in order to replenish the electrolyte to the matrix layer, first stop the operation of the battery, close the pulp 15b, and then close the pulp 15b.
3a, 13b open, electrolyte passage 71.

A blind plug 71 shown in FIG.
c.

72c respectively. and electrolyte tank 14
The electrolyte in the pulp 12a is opened to drain the electrolyte in the electrolyte passage 71.
72 respectively, and replenish the electrolyte to the matrix layer 1 through the replenishment hole 8a via the passage 8b and the replenishment hole 8a, and replenish the electrolyte to each matrix layer of the cell stack. After electrolyte replenishment, first, the pulp 12a Close the plug, remove the blind plug 71c l 72c, and open the remaining electrolyte.
b, discharge from 72b. Next, the pulp 15b was opened, air was blown into the water in the water tank 15 through the gas supply pipe 14 through the blower 14a from a gas supply source (not shown), and air was bubbled finely through the glass filter 14b at the tip to humidify the upper space 15c. make gas. The humidified gas is then passed through the blower 15a, the valves 13a and 13b, and the pipes 16 and 17.
By supplying air at the same pressure to the electrolyte passages 71 and 72 through 72a and discharging it through the open lowers 1b and 72b,
The electrolyte adhering to the passage wall is evaporated and removed.

In this case, the transpiration removal may be performed on either one of the electrolyte passages 71 and 72. For example, the electrolyte passage 7
1 is removed by transpiration, the pulp 13b is closed, the open lowers 2a and 72b of the electrolyte passage 72 are closed with blind plugs, etc., and the pulp 13a is opened to allow humidified gas to flow in from the open lower 1a to remove the electrolyte. Only the passage 71 is allowed to flow through the outlet lower 2a.
Make sure to drain it well.

After the completion of transpiration removal in the electrolyte passages 71, the pulp 13a is closed, the open lowers 1a and 71b are closed, and the electrolyte passages 72 are purged in the same manner as described above, thereby completing the transpiration removal in each electrolyte passage. In this embodiment, the humidifying gas can be passed through the open lower portion 1a and 72m of the upper portion.

Figure 4 shows the linear velocity Cm/8e (!) when humidified gas is supplied using air as the gas, and the phosphoric acid evaporation rate fh/d-h, which indicates the amount of phosphoric acid discharged when phosphoric acid is used as the electrolyte.
This shows the results of the experimental determination of the relationship with r.From this, it is understood that there is a proportional relationship between the logarithm of the gas linear velocity and the logarithm of the phosphoric acid evaporation rate. Therefore, when there is a large amount of cynic acid attached, it is possible to increase the linear velocity of the gas as shown in Figure 4. It can be removed by transpiration by increasing the time of air supply.

In this embodiment, humidified gas was used for transpiration removal, but it is also possible to remove the residue without humidification.

When using humidified scum, it may adhere to the electrolyte passages and
Since the concentration of the electrolyte, which has become high due to evaporation of water, can be diluted by the water in the humidifying gas, it is easier to remove the electrolyte by transpiration than when using a non-humidifying gas. Although the type of gas is not particularly specified, in consideration of safety, it is desirable to use an inert gas, for example nitrogen.

To mix water vapor into the gas, instead of using the humidified gas generator as described above, the water may be vaporized using the exhaust heat of one reformer or the exhaust heat of a fuel cell. Note that it is convenient to use exhaust gas of fuel gas or oxidant gas from the fuel cell, since these contain water vapor generated by electrochemical reaction.

〔Effect of the invention〕

As is clear from the above description, according to the present invention, after replenishing the electrolyte passageway with stained solutes and discharging the remaining electrolyte, the electrolyte passageway is supplied with stained solutes and the remaining electrolyte is discharged. By evaporating and removing the electrolyte adhering to the passage walls, there is no liquid junction caused by the electrolyte between the cells, which eliminates output loss due to leakage current between the cells and electrolytic corrosion of the battery components, thereby shortening the service life. This has the effect of providing a long fuel cell.

[Brief explanation of the drawing]

Fig. 1 is an exploded perspective view of a unit cell of a matrix fuel cell, Fig. 2 is a system diagram for replenishing electrolyte according to an embodiment of the present invention, and Fig. 3 is a partial cross section taken along line X-X of the electrolyte replenishment structure in Fig. 2. FIG. 4 is a graph showing the relationship between the gas linear velocity and the phosphoric acid evaporation rate.

Claims (1)

[Claims] In a method for replenishing electrolyte to the matrix layer of a single cell through an electrolyte passage provided to penetrate in the stacking direction of a cell stack formed by laminating single cells, when the battery is out of operation, the electrolyte is supplied to the electrolyte passage. A method for replenishing electrolyte for a matrix fuel cell, characterized in that the matrix layer is replenished with electrolyte by filling the replenishment passageway, and the electrolyte adhering to the walls of the passageway is evaporated and removed by passing gas through the replenishment passageway.