What is an azeotropic distillation system

hydrochloric acid

Means Concentration of Hydrochloric acid using the MoHA method from Pfaudler.

Hydrochloric acid, 31-35% HCl, is produced from weak hydrochloric acid using one of the Pfaudler MoHA processes.

Pfaudler offers two different processes for the medium hydrochloric acid concentration: One with a 2-pressure process and another based on extractive rectification.

The 2-pressure MoHA process uses the pressure dependence of the azeotropic composition of hydrochloric acid. While the azeotropic composition is about 24% HCl under vacuum conditions, this can be shifted to 16-18% HCl by rectification under pressure conditions with recovery of hydrochloric acid with a concentration of 31-35% HCl. The 16-18% HCl by-product can either be re-concentrated under vacuum conditions or enriched by the absorption of HCl from gas streams.

The MoHA process of extractive rectification uses extractive rectification to break up the azeotrope and extract water. The extractant is re-concentrated and reused internally. Depending on the general conditions, sulfuric acid, magnesium chloride or calcium chloride can be used as extraction agents.

High concentration of hydrochloric acid after this Pfaudler's HoHA process.

Using one of Pfaudler's HoHA processes, up to 100% HCl gas is produced from weak hydrochloric acid.

As with the MoHA process, Pfaudler offers two different processes for the high concentration of hydrochloric acid.

The 2-pressure HoHA process also uses the pressure dependence of the azeotropic composition of hydrochloric acid. While the azeotropic composition is about 24% HCl under vacuum conditions, this can be shifted to 16-18% HCl by rectification under pressure conditions with recovery of up to 100% HCl gas. The 16-18% HCl by-product can either be re-concentrated under vacuum conditions or enriched by the absorption of HCl from gas streams.

The HoHA process of extractive rectification uses extractive rectification to break the azeotrope. The extractant is re-concentrated and reused internally. Depending on the general conditions, sulfuric acid, magnesium chloride or calcium chloride can be used as extraction agents.

Hydrochloric acid recovery from gas streams

Hydrochloric acid up to 35% HCl can be obtained from HCl gas streams by absorption in water or weak hydrochloric acid. Pfaudler offers both adiabatic and isothermal absorption processes, depending on the framework conditions.