Measures to Address Abnormal Voltage Faults in Chlor-Alkali Electrolyzers

The electrolyzer is the core and critical equipment in chlor-alkali chemical production. It utilizes ion-exchange membrane electrolysis technology to electrolyze brine, producing key products such as caustic soda, chlorine gas, and hydrogen gas. Its operational stability and safety directly determine the production capacity, energy consumption, and product quality of the entire production line. Under long-term continuous production conditions, influenced by multiple factors such as medium corrosion, material impurities, operational parameter fluctuations, equipment aging, and improper maintenance, abnormal electrolyzer voltage not only affects the normal operation and equipment lifespan of the electrolyzer but may also trigger safety hazards such as gas crossover and pressure imbalance.

1. Core Causes of Abnormal Electrolyzer Voltage

1.1 Substandard Brine Purification Water Quality

When the quality of the brine purification process fails to meet standards, magnesium ion content and suspended solids content may exceed limits. These impurities enter the electrolyzer along with the purified brine, forming deposits on the surface of the ion-exchange membrane and blocking the membrane pores, resulting in degraded ion-exchange performance. The increase in membrane resistance directly leads to elevated cell voltage.

1.2 Imbalanced Production Process Parameter Control

If the catholyte caustic soda concentration of the electrolyzer is controlled well above the process standard value, the excessive osmotic pressure of the caustic solution will increase the resistance of the ion-exchange membrane. If the operating temperature of the electrolyzer is controlled too low, the ion migration rate of the electrolyte will decrease, leading to increased ohmic voltage drop within the electrolyzer. If the pressure differential between the anode and cathode chambers is unreasonably controlled, resulting in reverse pressure differentials or excessive fluctuation amplitude, the membrane-to-electrode contact tightness will decrease, increasing membrane resistance. If the acidity of the anolyte is controlled too high, the corrosion process of the anode will accelerate, which also indirectly causes the cell voltage to rise.

1.3 Natural Aging of the Ion-Exchange Membrane

During long-term operation, the ion-exchange membrane is continuously subjected to multiple effects including chemical medium corrosion, electrolyte erosion and wear, and impurity adsorption and blockage, leading to natural aging phenomena. Its ion-exchange capacity and permeation stability gradually decline, and the membrane resistance steadily increases with operating time, ultimately causing a slow and persistent rise in cell voltage. This is a typical normalized fault trigger for equipment under long-term operation.

1.4 Non-Standard Equipment Load Adjustments

Excessive adjustment amplitude and excessively rapid changes in the operating current of the electrolyzer will lead to uneven electrolyte distribution within the electrolyzer, causing a mismatch between ion migration rate and current intensity, resulting in abnormal cell voltage elevation. Additionally, after increasing the operating load of the electrolyzer, if the process parameters such as caustic soda concentration, anolyte and catholyte circulation volume, and electrolyzer temperature are not promptly optimized and adjusted accordingly, this will also lead to elevated cell voltage.

2. Remedial Measures

2.1 Comprehensive Inspection of Equipment Operating Conditions

Conduct a comprehensive inspection of the electrolyzer's operating status, with a focus on confirming whether the conductive busbar joints of the electrodes exhibit overheating or excessive contact resistance, whether the indications of relevant instruments are normal and free from deviations, and progressively narrow down the scope of fault investigation.

2.2 Strict Control of Brine Water Quality

Re-sample and analyze the quality of the secondary purified brine, focusing on testing whether key indicators such as calcium and magnesium ion content, suspended solids content, and pH value meet the process standard requirements. If any exceedances are found, adjust the dosage of purification agents, switch to the standby chelating resin tower, and if necessary, reduce the operating load of the electrolysis process to decrease the impurity load on the ion-exchange membrane and mitigate the extent of cell voltage elevation.

2.3 Regulation of Process Parameters

Appropriately reduce the operating current of the electrolyzer to decrease the electrochemical reaction intensity; moderately raise the operating temperature of the electrolyzer to improve the ion migration performance of the electrolyte; precisely adjust the concentration of the catholyte caustic soda to control it within the process standard range; readjust the pressure differential between the anode and cathode chambers of the electrolyzer to comply with technical standard requirements; suspend the addition of hydrochloric acid to the anode chamber to reduce the acidity load of the anolyte and decrease membrane resistance.

Abnormal electrolyzer voltage is a comprehensive manifestation of multi-dimensional issues encompassing water quality management, process parameters, equipment status, and operational standards. In daily production, source prevention and control should be the core, combined with precision maintenance, standardized operations, and real-time inspections to build a comprehensive prevention and control system, proactively resolving various triggering hazards and reducing the occurrence of abnormal voltage faults.