Method and system for recycling byproduct hydrogen chloride in aromatic chlorination production process

The invention discloses a method for recycling a byproduct hydrogen chloride in an aromatic chlorination production process, which comprises the following steps: the byproduct hydrogen chloride exhaust is introduced into a hydrogen chloride purification tower through the lower part, and makes counterflow contact with an absorption solution in the hydrogen chloride purification tower so as to remove aromatic impurities in the hydrogen chloride gas; the purified hydrogen chloride exhaust and oxygen are subjected to catalytic oxidation reaction under the action of an oxidation catalyst, so that the hydrogen chloride is catalytically oxidized into chlorine gas; the gas mixture after the oxidation reaction of hydrogen chloride is subjected to heat exchange through frozen salt water; the gas mixture subjected to freezing dewatering is directly subjected to continuous catalytic chlorination with fresh chlorine gas and fresh aromatics to produce chlorinated aromatics; and the hydrogen chloride exhaust containing aromatic impurities enters the hydrogen chloride purification tower through the lower part and is subjected to absorption purification again. The invention also discloses a system for recycling byproduct hydrogen chloride in an aromatic chlorination production process. The method removes the complex procedure of oxygen separation after hydrogen chloride oxidation, thereby simplifying the process route and greatly lowering the equipment investment cost.