Hydrochloric Acid

Systems

Hydrochloric acid recovery systems can be divided into thee ranges, according to the physical properties of the acid.

Pre-Concentration of Hydrochloric Acid using the Pfaudler PoHA Process

HCl forms an azeotropic mixture with water at a concentration of approximately 24% HCl.

Using the PoHA process, weak hydrochloric acid is concentrated up to this composition through rectification.

Medium Concentration of Hydrochloric Acid using the Pfaudler MoHA Process

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 concentration of hydrochloric acid: one uses a dual pressure process and one uses extractive rectification.

The Dual Pressure MoHA process takes advantage of the pressure dependence of the azeotropic composition of hydrochloric acid. While the azeotropic composition at vacuum conditions is about 24% HCl, this can be shifted to 16-18% HCl through rectification at pressurized conditions, recovering hydrochloric acid, 31-35% HCl. The 16-18% HCl byproduct can be ether reconcentrated at vacuum conditions or fortified through the absorption of HCl from gas streams.

The Extractive Rectification MoHA process uses extractive rectification to break up the azeotrope and extract water. The extractive agent is reconcentrated and internally recycled. Depending on the frame requirements, sulfuric acid, magnesium chloride brine, or calcium chloride brine can be applied as extractive agents.

High Concentration of Hydrochloric Acid using the Pfaudler HoHA Process

Up to 100% HCl gas is produced from weak hydrochloric acid using one of Pfaudler HoHA processes.

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

The Dual Pressure HoHA process also takes advantage of the pressure dependence of the azeotropic composition of hydrochloric acid. While the azeotropic composition at vacuum conditions is about 24% HCl, this can be shifted to 16-18% HCl through rectification at pressurized conditions, recovering up to 100% HCl gas. The 16-18% HCl byproduct can be ether reconcentrated at vacuum conditions or fortified through the absorption of HCl from gas streams.

The Extractive Rectification HoHA process uses extractive rectification to break up the azeotrope and to extract water. The extractive agent is reconcentrated and internally recycled. Depending on the frame requirements, sulfuric acid, magnesium chloride brine, or calcium chloride brine can be applied as extractive agents.

Hydrochloric Acid Recovery from Gas Streams

Hydrochloric acid up to 35% HCl can be recovered from HCl gas streams through absorption in water or weak hydrochloric acid. Pfaudler offers adiabatic as well as isothermal absorption processes, depending on the frame condition.