Chlor-alkali (CA) refers to chlorine and caustic soda (NaOH) manufacturing. These are among the top ten chemicals produced worldwide and are main ingredients in the manufacture of pharmaceuticals, detergents, disinfectants, herbicides, pesticides and PVC. Chlorine and caustic soda are made by the electrolysis of brine (NaCl).
In the preferred membrane process of CA, level instruments control saturated brine and demineralized water feed, and caustic liquid level. Level control maintains a high enough level in the anode and cathode compartments to ensure membrane saturation, thus preventing any exchange of gases via the membrane in the upper part of the electrolysis cell.