Production of hydrochloric acid by removing hydrogen chloride from combustion gas

Hydrochloric acid having a substantially constant HCl content of 20 to 36% is produced continuously by removing hydrogen chloride from hot combustion gas. To this end, hot combustion gas containing 1 to 10% by volume of HCl and steam, this gas being obtained by the joint combustion of off-gases containing chlorinated hydrocarbons and liquid residues of chlorinated hydrocarbons, is introduced into a quenching zone, and quenched therein, down to a temperature lower than its dew point, by means of cooled hydrochloric acid containing hydrogen chloride in a concentration of 20 to 36%, which concentration corresponds to the concentration of the hydrochloric acid which is to be produced. The resulting gas-liquid mixture is separated in an absorption cooling zone into cooled hydrochloric acid and cooled combustion gas containing 0.1 to 1% by volume of HCl. The cooled hydrochloric acid is introduced into a reservoir zone capable of receiving a multiple of the quantity of hydrochloric acid produced per hour, and recycled from the said reservoir zone to the quenching zone. Additional 20 to 36% hydrochloric acid produced is taken out of the quenching cycle.