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Hydrochloric Acid Processes

Acid handling requires state-of-the-art processes. For treatment of acids and waste streams from hydrochloric acid processing, our tailor-made plants satisfy special requirements by combining most modern technology with proven materials.

KBR offers the full range of hydrochloric acid (HCl) treatment and processing, starting from simple distillation over rectification to extractive and dual-pressure rectification, in order to achieve any purity and concentration over the full range up to almost water-free, 100% dry gas. Additionally, the opposite absorbing dry HCl gas, in order to achieve a desired lower HCl concentration is offered.

“For hydrochloric acid processing, we specialize in the treatment of acids and waste streams, which provide economic and environmental benefits.”

We offer process designs and technology for concentration of HCl byproduct from chemical process like phosgenation for recycle or sale to third parties, for concentration of diluted HCl streams from vent scrubbers, and HCl removal from waste water for yield or environmental reasons. We also develop new applications of our technology and operate a lab with pilot plants that allow us to develop and scale up such new applications very reliably and efficiently for our customers.

We design small-scale plants, in which only a few hundred kilograms of acid per hour are recovered, up to world-scale plants.


Pre-concentration is used to treat raw hydrochloric acid with low HCl content to achieve up to 24 wt% HCl concentration. Water is removed overhead by rectification, while the water/hydrochloric acid azeotrope is removed in the bottom stream. According to the operating pressure, the azeotropic concentration is between 18 and 24 wt% HCl. Volatile and non-volatile impurities are also removed from the HCl stream during Pre-concentration.

Medium Concentration

Hydrochloric acid at 30–35 wt% concentration can be produced from any diluted raw hydrochloric acid. Using extractive rectification, weak hydrochloric acid is mixed with an extraction agent and fed into the rectification column. Water is absorbed by the extraction agent and the volatility of the hydrochloric acid stream is increased. At the head of the column, medium-concentration hydrochloric acid is refined. Diluted extraction agent is obtained in the sump, reconcentrated in an external evaporator and fed back into the column. CaCl2, MgCl2 or H2SO4 may be used as extractive agents to remove water. The dual-pressure process is also available for the production of medium-concentration hydrochloric acid. In the first step, preconcentrated acid at 22–24 wt% HCl is split into the head product, with about 30–35 wt% HCl and the sump product azeotropic acid using rectification under pressure. In the second step, the azeotropic acid is restrengthened by evaporating water at vacuum conditions up to 22–24 wt% HCl and then recycled to the first step. As an alternative, the azeotropic acid can be restrengthened using concentrated HCl gas.

High Concentration

In order to produce high-concentration HCl gas up to 100 wt% HCl, the same process configuration for medium concentration can be applied, while varying the operating conditions.


Spent hydrochloric acids of various origins containing organic and inorganic impurities can be recovered and purified using KBR's PLINKE technology.

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Hydrochloric Acid Processes Opportunities

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