Breakdown of the electrode mesh in ion membrane electrolyzers
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Help! One of our company’s electrolyzers, which has been modified by Dinola and equipped with Asahi Kasei ion exchange membranes, experienced fluctuations in the EDIZA potential difference a couple of days ago. The system was manually shut down at that time (since the interlock system wasn’t active), and membrane leakage became severe. Upon inspection, it was found that the cathode mesh, the anode mesh, and the ion exchange membrane all had two large holes in them (with a diameter of about 3 centimeters). Prior to this, the voltage of this electrolyzer had remained stable and normal, and there were no issues with the quality of the brine. Has anyone else encountered a similar situation? What could be the cause?
The ion membrane may originally have pores, and these pores enlarge or tear during operation; an electrolyte pathway is formed at these pores between the two electrodes, or the two electrodes come into direct contact with each other, resulting in breakdown.
On the one hand, saltwater contains a high level of iron; when this accumulates to a certain extent, it causes a short circuit between the anode and cathode, leading to the breakdown of the electrode mesh. On the other hand, if the membrane has pores, alkali can seep into the anode and corrode it, resulting in holes in the electrode.
It is possible that the feed pipe for the electrolyte in the relevant unit is blocked, causing the electrolyte level inside the electrolysis cell to drop significantly, which in turn leads to a short circuit between the electrodes and results in the destruction of the electrode mesh and membrane. It can be said that your company was fortunate in spite of the misfortune, as timely measures were taken to prevent an accident in the chlorine system. Here is some advice for you: The EDIZA electrode potential interlock is a fundamental guarantee for the safe operation of the electrolyzer, and it should be activated promptly once the electrolyzer is running stably.
Fluctuations in the potential difference indicate that membrane leakage has occurred. It was absolutely correct to stop the process in a timely manner; it’s possible that a small explosion occurred due to the mixing of chlorine and hydrogen either after or at the time of stopping, which resulted in pinholes in the membrane measuring three centimeters in diameter.
The brine entering the tank is equipped with a filter screen, and it is recommended to clean it. By checking the trend of the electrolyzer voltage, it can be observed that in some cells the voltage rises rapidly over a short period of time, with the voltage difference reaching the interlock value. The reason for this phenomenon may be blockages in certain feed pipes for the brine; over time, the potential in the electrolysis cell decreases, and the current density increases, leading to the breakdown of the ion membrane.