Absorption of HCL Gas
The absorption of HCL in water or dilute HCL acid is a central operation in the production of HCL acid. However, this technique is also often used for cleaning waste gases.
The HCl gas is admitted at the bottom of a column, while the absorption liquid is fed in at the top. Gas and liquid flow in counter-current to ensure optimum absorption. The height, diameter and internals are designed to ensure that the desired acid concentration is obtained and the purity of the gas ismaximized. The hot stream of acid is cooled in an integral or separate heat exchanger.
The dissolution of HCL in water is followed by a strongly exothermic reaction in the liquid.
To obtain a solution with a maximum HCl concentration, removal of the appropriate amount of heat is necessary – isothermal absorption. For this reason, water-cooled falling-film absorbers are used for the production of hydrochloric acid. With lower HCl concentrations in the feed gas, adiabatic absorption isan alternative. Because the absorption rate decreases at lower concentrations, multistage scrubbers are required; these are designed as columns with random or structured packings.
For recovery of hydrogen chloride from inert gas streams with fluctuating concentrations, we offer a system for absorption with water followed by production of HCL gas by distillation.
Capacity and available sizes
The absorption systems can be designed for a capacity of 0.5 to 360 t/d 100% HCL per system. The equipment sizes are matched to the customer's needs.