Recovering hydrogen chloride into water or weak acid. Corrosive duty demanding the right alloy or lining.
Hydrogen chloride is extremely soluble in water and the absorption releases a large amount of heat. That combination — fast absorption, strong exotherm, and a product that is hydrochloric acid — means the engineering challenge is materials and heat removal rather than mass transfer.
Duties split between recovery, where the aim is to make saleable acid at strength, and abatement, where the aim is simply to keep HCl out of the stack.
