JPH0157469B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for preventing leakage current in an electrode reaction device, and more specifically to a structure in which an electrolytic solution is introduced from the outside into a positive electrode chamber and a negative electrode chamber, and flows out after an electrode reaction. The present invention relates to a method for preventing leakage current in an electrode reaction device such as a liquid flow type electrolytic cell or battery.

Conventionally, this type of electrode reaction device consists of a single cell group in which a positive electrode chamber 1 and a negative electrode chamber 2 are stacked in series with a diaphragm in between, as shown in FIG. 3, branch pipes 4A and 6A branched from these, and branch pipe 5A for draining the liquid after the electrode reaction from the electrode chamber.
and 7A, and main pipes 5 and 7 to which these are connected.

In the above-mentioned conventional device, when the electrolyte is fed into and out of each single cell 1 and 2 in parallel, the current flows through the diaphragm provided between the positive electrode chamber and the negative electrode chamber, and is consumed by the electrode reaction. However, in addition to this, the electrolyte also flows into the electrolyte flow paths connecting the positive electrode chamber and the negative electrode chamber, that is, the main pipes 4, 6, 5, and 7, and the branch pipes 4A, 6A, 5A, and 7A. Much of the current flows out of the system and becomes leakage current. Such current is usually unrelated to the electrochemical reactions that occur within the positive and negative electrode chambers, and often results in power loss as it is. The proportion of such leakage current can reach about 10% when the number of single cells is increased, but it has been almost ignored in the past. As a countermeasure to this problem, attempts have been made to reduce the leakage current by increasing the length of the electrolytic solution flow path or decreasing its diameter to increase the electrical resistance in that portion. Therefore, with such measures, it is difficult to significantly reduce leakage current, and when operating for a long period of time, the energy loss becomes enormous.

Furthermore, Japanese Patent Publication No. 49-38897 discloses a method for preventing leakage current by introducing air bubbles into the electrolyte flow path from an air pipe separately provided, but this method introduces air bubbles from the outside. However, a special bubble introduction device had to be installed separately, and the power cost increased, so it was not an efficient method. Therefore, there has been a long-awaited method for reducing leakage current more efficiently.

The purpose of the present invention is to eliminate the drawbacks of the above-mentioned prior art,
It is an object of the present invention to provide a method that can further effectively reduce leakage current in a simple manner.

As a result of further research on technology to increase electrical resistance by mixing air bubbles into the electrolyte fluid path, we found that by generating air bubbles in the fluid flow path by electrolysis or the vapor pressure of the electrolyte solvent, leakage can be prevented. discovered that current can be prevented even more efficiently,
This has led to the present invention.

That is, the present invention provides an apparatus in which a plurality of single cells each having a positive electrode chamber and a negative electrode chamber are arranged via a diaphragm, and an electrolytic solution is passed through the cells to perform an electrode reaction. It is characterized in that air bubbles are mixed into the liquid in at least a part of the passage.

In the present invention, the smaller the bubbles and the larger the amount of bubbles generated in the electrolyte flow path, the greater the effect of cutting off the electrolyte, and the more difficult it is for leakage current to flow. In addition, if the flow path is relatively small in diameter,
It is also effective to cover the entire cross section of the flow path with one bubble. The bubbles mixed into the electrolyte only need to be mixed in at least a part of the electrolyte flow path, and preferably the bubbles are generated or introduced from the inflow side of the electrolyte and allowed to exist for a long time in the subsequent flow path. preferable. In addition, in order to prevent air bubbles from entering the single cell, that is, the positive electrode chamber or the negative electrode chamber, the piping structure is designed to prevent air bubbles from entering the electrode chamber as much as possible by utilizing the difference in specific gravity between the electrolyte and the air bubbles, that is, the buoyancy of the air bubbles. This is very important.

The method of introducing bubbles in the present invention is to place an electrode for gas generation directly in the electrolyte flow path and generate bubbles. Effective methods include using the liquid as air bubbles, and placing a capillary or the like for introducing a low-boiling point solvent into the electrolytic solution flow path and vaporizing the solvent there.

Hereinafter, the present invention will be explained in more detail with reference to the drawings.

In the embodiment shown in FIG. 2, a pair of electrodes 11 are arranged to face each other in a flow path 10 of the electrolytic solution 3, and gas is directly generated there and mixed into the electrolytic solution.
This embodiment can be easily implemented at low cost because it is sufficient to simply dispose the electrode in a protruding manner within the electrolyte flow path.

Further, FIG. 3 shows a preferred arrangement example of the electrolyte distribution piping of an electrolytic cell in which single cell groups are arranged in series. In the figure, this device consists of a positive electrode chamber 1 and a negative electrode chamber 2 stacked in series with a diaphragm in between.
and electrolyte 3 in the positive electrode chamber or negative electrode chamber (single cell).
A main pipe 4 for feeding the water, and a U-shaped branch pipe 12 that branches from the main pipe 4 and connects to the single cell.
, a branch pipe 5A provided upright above the single cell, and a main pipe 5 connected to these branch pipes.
and a connecting pipe 1 that bypasses the main pipe 4 on the inflow side and the main pipe 5 on the outlet side at one end of the single cell group.
It mainly consists of 3. In this case, the main pipe 4 is arranged above the electrolyte inlet of the single cell, and when the liquid flows through the U-shaped pipe connecting the main pipe 4 and the single cell, air bubbles are trapped in the U-shaped pipe, It is designed so that it does not enter a single cell. In other words, due to the difference in specific gravity between the electrolyte and the bubbles (the buoyancy of the bubbles), the bubbles rise and separate while passing through the U-shaped tube and reaching the electrolyte inlet. It is discharged to the outside of the system through the main pipe 4, the communication pipe 13, and the main pipe 5 on the outlet side. In this case, in order to enhance the current blocking effect, it is desirable to reduce the diameter of the portion 13A of the communication pipe 13.

According to the above embodiment, by mixing air bubbles only in the main pipe 3, communication pipe 13, and main pipe 5 through which the electrolytic solution flows, the current blocking effect is greatly improved, and leakage current can be effectively prevented. can. Furthermore, since air bubbles do not enter the single cell 1 or 2, the operation of the electrolytic cell can also be stabilized.

In the above embodiment, the U-shaped tube 12 was used as the gas-liquid separation means between the main pipe 4 and the single cell 1 or 2, but other gas-liquid separation means, such as the communication pipe 12A
A liquid reservoir may be provided with a gas vent hole.

As described above, according to the present invention, leakage current in electrode reaction devices such as electrolytic layers and batteries can be effectively prevented by the bubbles generated inside the electrolyte flow path, and energy saving of these devices can be achieved.

Examples and specific examples of the present invention will be described below.

Experimental Example 1 Platinum mesh was placed at both ends of a polyvinyl chloride tube with a length of 1 m and an inner diameter of 10 mm, and the resistance between the platinum mesh was measured using an AC bridge method and a circuit tester. A 1N sulfuric acid aqueous solution was flowed into the tube as an electrolyte at a flow rate of 100 ml per minute. When bubbles were created in the sulfuric acid aqueous solution by the method shown in Figure 2, in which gas (electrolytically generated) was introduced, the measured resistance value was approximately 30 times higher than before the gas was introduced. The results revealed that the electrical resistance of the electrolyte flow path increased significantly and was effective in reducing leakage current.

Example 1 An electrolytic cell consisting of 20 single cells having the electrolyte flow path shown in FIG. 3 was prepared, and electrolysis experiments using acidic hydrochloric acid, iron chloride, and aqueous solutions were conducted. Both positive and negative electrode liquids are 1N hydrochloric acid acidic 1 mol/ferrous chloride and 1 mol/
Ferric chloride aqueous solution is sent to the single cell group of this electrolytic cell at a flow rate of 250 ml/min, and electrolysis is performed at a constant current of 4 A to remove the divalent iron in the electrolyte at the inlet and outlet of the electrolytic cell,
The trivalent proportion was measured by voltammetry. Furthermore, no phenomena considered to be side reactions such as gas generation were observed during electrolysis. The ratio of the required current value calculated from the amount of energization and the amount of iron subjected to electrolysis is approximately 1:0.97, and the leakage current flowing through the electrolyte flow path is approximately 3
%It was considered.

Next, during an electrolysis experiment under the same conditions, gas was introduced into the channels 4 on the electrolytic cell inlet side for positive and negative electrode liquids by alternating current electrolysis. As a result, the leakage current was reduced to 0.7% or less.

As a method of generating gas through this electrolysis,
A platinum wire wound around the electrolyte flow path was placed as an electrode, while a counter electrode chamber (anode chamber) was provided outside the electrolyte flow path via a diaphragm, and an AC voltage was applied to generate hydrogen. . It was difficult to accurately detect the decrease in leakage current because it is thought that a reaction between iron (trivalent) itself by the platinum electrode and a reaction between hydrogen gas and iron (trivalent) occur. Since the current required for generation is small, its effect can be sufficiently measured, and as a result, the leakage current is at least 1
It was found that it was less than %.

Example 2 Platinum wire mesh was placed at both ends of a fluororesin tube with a length of 1 m and an inner diameter of 10 mm, and the resistance between the wire meshes was measured using an AC bridge method and a circuit tester. A 1 mol/aqueous sodium sulfate solution heated near the boiling point was poured into the tube at a flow rate of 100 ml per minute. A nichrome wire was installed on the inlet side of the aqueous solution tube, and electricity was applied to partially boil the aqueous solution near the nichrome wire to create water vapor bubbles, which were mixed into the aqueous solution. After the nichrome wire was energized, the resistance between the platinum wire meshes increased by about 20 times compared to the value after energization, and it was found that the leakage current was significantly reduced.

[Brief explanation of drawings]

FIG. 1 is an explanatory diagram showing a conventional electrode reaction device consisting of a group of single cells in which a positive electrode chamber and a negative electrode chamber are electrically stacked in series, FIG. 2 is a diagram illustrating the bubble mixing method in the present invention, FIG. 3 is an explanatory diagram of an electrode reaction apparatus showing still another embodiment of the present invention. 1... Positive electrode chamber (single cell), 2... Negative electrode chamber (single cell), 3... Electrolyte flow, 4... Electrolyte flow path,
11...Gas generation electrode.

Claims (1)

[Scope of Claims] 1. An electrolyte that communicates between the single cells of an apparatus in which a plurality of single cells each having a positive electrode chamber and a negative electrode chamber are configured via a diaphragm, and an electrolytic solution is passed through the cells to perform an electrode reaction. In the leakage current prevention method of mixing air bubbles into at least a part of the liquid in the liquid passage, the air bubbles mixed into the electrolyte are generated by an electrolytic method using a device installed in the electrolyte liquid passage, and/or Or, a method for preventing leakage current in an electrode reaction device, characterized in that the leakage current is generated using the vapor pressure of the electrolyte solvent itself. 2. A method for preventing leakage current in an electrode reaction device according to claim 1, characterized in that the bubbles are separated at the cell entrance and mixed into the electrolyte passage so that the bubbles do not enter the cell. .