Chlor-alkali

NCl₃ is a hazardous byproduct that is formed in the electrolyzer when amines are present in the brine feed. NCl₃ is an explosive liquid with a detonation pressure that is greater than ammonium nitrate – a common mining explosive. NCl₃ can also accumulate in the liquid phase due to its solubility in chlorine and its higher boiling point; it is essential that NCl₃ levels are continuously monitored throughout the plant to ensure explosion risks are minimized.

Moisture levels need to be monitored for sections of the plant designed to handle dry chlorine. Under normal operation, carbon steel forms a ferric chloride layer that protects pipes and process equipment. If the partial pressure of moisture exceeds the vapor pressure of the ferric chloride hydrate layer, the protective layer preventing corrosion may not remain in place. This can lead to pipe failures and the leak of dangerous levels of chlorine.

Hydrogen is co-produced by electrolysis. Increases in hydrogen due to leakage across membranes or process changes can lead to explosions. Especially during drying, careful attention must be paid to hydrogen levels as drying concentrates hydrogen.

Chlorine must be monitored throughout the process to ensure the efficiency of electrolysis, cooling, drying and liquefaction operations. Non-condensable chlorine vapors leaving the liquefaction unit must also be scrubbed and the stack emissions must be monitored to ensure environmental regulation compliance.