Chlor-Alkali Process:

Sodium Hydroxide (NaOH), Brine (NaCl), Hydrochloric Acid (HCl), Sodium Hypochlorite (NaClO)

Sodium hydroxide (NaOH), brine (NaCl), hydrochloric acid (HCl), sodium hypochlorite (NaClO) measurement in chlor-alkali process

Sodium hydroxide or caustic soda, NaOH is used as a caustic base and alkali in a wide range of industries. It is manufactured by electrolysis of sodium chloride solutions.
Typically, sodium hydroxide is delivered in 30-40% NaOH concentrations to customers, who will further dilute it with water for use at concentrations of 14-15 % NaOH. 

Vaisala Polaris™ Process Refractometer is used to measure the concentration at different phases of the process:

  • Sodium chloride, NaCl concentration measurement before electrolytic cell and in brine recirculation line
  • Hydrogen chloride, HCl
  • Sulfuric acid, H2SO4 concentration measurement before feeding the product to the dryer 
  • Sodium hydroxide, NaOH measurement prior to and after the evaporation
  • Sodium hypochlorite (NaClO)

Several choices of refractometer wetted parts material are available for different chemicals.

Learn the details of the chlor-alkali process measurements from the application note.

Download the application note in PDF by filling the form.

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