Apparatus for continuous liquid-phase oxidation reaction

In a reaction vessel for continuous liquid-phase oxidation for producing an aromatic carboxylic acid sparingly soluble in a lower aliphatic carboxylic acid solvent by a liquid-phase oxidation of the corresponding alkyl aromatic compound with a molecular oxygen-containing gas under high temperature and high pressure in the presence of the lower aliphatic carboxylic acid solvent and an oxidation catalyst, said reaction vessel having a lower portion for holding a liquid phase and an upper portion for holding a vapor phase, said reaction vessel including a vapor outlet at the top of the reaction vessel, an outlet for the reaction product and an inlet for an oxygen-contining gas adjacent the bottom of said reaction vessel, stirring means disposed in the reaction vessel, a conduit for supplying a liquid mixture of raw material and solvent having the discharge end thereof in the lower portion of the vessel, a conduit for supplying a solvent-catalyst liquid mixture to the lower portion of the vessel adjacent the bottom of the reaction vessel, a condenser connected to said vapor outlet and a conduit disposed in communication with said condenser at one end with the discharge end disposed in the lower portion of said vessel for recycling condensed liquid, the improvement comprising a spraying means disposed in the upper portion of the vessel for supplying additional solvent-catalyst liquid mixture, having downwardly and outwardly slanted discharge holes and located at a position of about 1/20 to about 1/3 times the height of the reaction vessel above the line between the upper and lower portions of the vessel to thereby supply continuously said solvent-catalyst liquid mixture in a finely divided form onto the inside wall of the reaction vessel immediately above said line to remove reaction products deposited on said wall.