AppliTek NV

Online monitoring solutions for determination of iron in hydrochloric acid - Monitoring and Testing

Levels of iron in liquid hydrochloric acid (HCl) are precisely monitored by means of the EZ-HCl analyzer system. Iron oxides that dissolve in the HCl can lead to the formation of ferrous chloride (FeCl2) and compromised purity of the end product. With increasing concerns over safety and efficiency in the chlorine manufacturing processes, AppliTek has investigated the use of proprietary on-line analyzer systems to monitor and control the HCl synthesis. Each of these on-line analyzer systems has been selected to control a specific part of the burner, by using techniques such as multi-wavelength infrared, thermal conductivity and wet-chemical liquid analysis.


Hydrochloric acid or HCl is one of the main primary products of the chlor-alkali industry and commonly produced by the exothermic reaction of hydrogen and chlorine, fed at controlled rates inside a burner. The burner consists of two concentric tubes with chlorine flowing through the inner tube and hydrogen through the outer annulus. Above the burner, the gases are ignited to produce hydrogen chloride gas. For optimum combustion and low free chlorine content in acid, the gases are burnt with about 10% excess volume flow of hydrogen. The HCl gas flows from the combustion chamber into an integrated isothermal falling-film absorber. The gas is then absorbed by water or weak acid. The absorber is either co-current or counter-current depending on the type of synthesis unit. The hydrochloric acid is normally produced with less than 1 ppm free chlorine. By adjusting the absorption water (weak acid) supply rate, the desired hydrogen chloride (HCl) solution concentration is obtained.

Parameters: Iron

Measuring ranges

0 – 1 ppm iron (Fe)