JPS6152386A - Detection of interrupted supply of raw material brine - Google Patents

Abstract

PURPOSE:To detect easily the interrupted supply of raw material brine to an ion exchange membrane type salt electrolytic cell and to prevent the generation of an accident by detecting the abnormally high increase of the voltage impressed to the electrolytic cell as compared to the voltage increase before adequate time. CONSTITUTION:The interrupted supply of the raw material brine is detected by detecting whether the increase of the voltage impressed to the ion exchange membrane method salt electrolytic cell is >=0.07V or above as compared to the voltage increase 30-40min before. The generation of such accidents as the breakdown of the ion exchange membrane, electrode, etc., the mixing of the raw material brine and caustic soda and further explosion, etc. as a result of mixing of hydrogen and chlorine is thus prevented. The reason for limiting the above-mentioned comparison time is: The accident such as the failure of the ion exchange membrane arises in about one hour after the interrupted supply of brine and therefore the time is limited to max. 40min by allowing for the time to take a required remedy. The time below 30min is inadequate as the cause for the voltage increase is often different from the cause for the interrupted supply of the brine.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for detecting the interruption of the supply of raw saline solution to an ion-exchange membrane salt electrolyzer.

The conventional mercury method salt electrolysis has been converted to the diaphragm method or the ion exchange removal method salt electrolysis due to the problem of mercury pollution. Among these, ion-exchange removal salt electrolysis is attracting attention because the resulting caustic soda aqueous solution has good purity.

By the way, in ion-exchange removal method salt electrolysis, when the supply of raw salt water is interrupted, the voltage applied to the electrolytic cell gradually increases, and if left as it is, the ion-exchange membrane will collapse.

There is a danger that the electrodes will be destroyed and not only will the raw saline solution and caustic soda mix, but also hydrogen and chlorine will mix, resulting in an explosion.

The present inventors investigated a method for detecting the interruption of the supply of saline water and found that the applied voltage increases after a certain period of time after the supply of saline water was interrupted, and finally arrived at the present invention. It was.

That is, the present invention is characterized in that it detects whether or not the voltage applied to the ion-exchange membrane salt electrolyzer is 0.07 volts or more compared to 30 to 40 minutes ago. This is a method for detecting supply disruption.

The voltage applied to the ion exchange membrane method salt electrolyzer is usually 3.0
The voltage is about 0 to 3.70 volts, and the voltage fluctuation in each electrolytic cell is within ±0.03 volts. Therefore, if a change larger than this voltage fluctuation value is observed, it can be detected that an abnormality has occurred in the electrolytic cell.

By the way, the voltage rise after the supply of raw brine to the electrolytic cell is interrupted is very gradual, so normally the interruption of the supply of raw brine is not detected as a voltage fluctuation, but 30 to 4
By comparing the applied voltage with the voltage applied 0 minutes ago, the voltage increase can be detected.

On the other hand, when the supply of the caustic soda aqueous solution side is interrupted, the change in the applied voltage is extremely small, and the increase in the applied voltage is 60%.
Abnormalities cannot be detected unless the applied voltage is compared with the voltage applied more than minutes ago.

In addition, although the amount of electricity applied varies depending on the busy schedule, the ion exchange membrane may be torn or the electrodes may be destroyed within an hour or so after the supply of saline water is interrupted, so an abnormality will be detected within 40 to 45 minutes after the supply of saline water is interrupted and countermeasures will be taken. The maximum comparison time is 40
minutes is preferable. In addition, if the comparison time is less than 30 minutes, it is often an abnormality different from saline supply disruption.
It cannot be used to detect disruption of saline water supply.

The method of the present invention merely examines changes in the voltage applied to the electrolytic cell, and the interruption of the saline water supply can be detected in an extremely simple manner, so it has great industrial value.

Claims (1)

[Claims] 1) The increase in voltage applied to the ion-exchange membrane method salt electrolyzer is 3
A method for detecting supply disruption of raw saline solution, characterized by detecting whether the voltage is 0.07 volt or more compared to 0 to 40 minutes ago.