FIELD: biotechnology.
SUBSTANCE: invention relates to a process for treating acetic acid-solvent in an oxidation unit of an industrial plant for the production of purified terephthalic acid PTA. Process for treating the acetic acid-solvent in the oxidation unit of an industrial plant for PTA comprises the following steps: feeding the RTA (raw terephthalic acid) suspension with acetic acid under pressure from the oxidation unit of the industrial plant for PTA upstream into the filtration zone of the pressure filter for separation of solid particles and acetic acid from a suspension of raw terephthalic acid RTA to form a filtered RTA precipitate, separated mother liquid and residual liquid in a filtrate tube; separated mother liquid is discharged into the mother liquid reservoir; and the residual liquid in the filtrate tube is displaced into the mother liquid reservoir; washing the filtered RTA precipitate step-by-step in several washing zones after the rotation of the pressure filter, in which each washing zone, except for the washing zone for the last washing step, is connected to the washing liquid reservoir, respectively, each washing liquid reservoir supplies the washing liquid to a suitable washing zone to wash the filtered RTA precipitate; and in the washing zone for the last washing step, fresh process water is used as the washing liquid, while at the remaining washing stages, the washing liquid is supplied from the last washing stage back to the washing liquid reservoir of the previous washing step by the multi-stage countercurrent washing method; and wherein the step of displacing the residual liquid in the filtrate pipe at each washing step into the washing liquid reservoir of the respective stage is included in the stepwise washing; and the feed of the filtered RTA precipitate which has been treated with several washes is transferred to the discharge zone after the pressure filter is rotated, and the subsequent feeding of the filtered RTA precipitate is transferred from the discharge zone to the pulp recovery reservoir by backwash with nitrogen gas and by gravity, so that the filtered RTA precipitate is mixed with external process water and a pulp is formed, wherein the step of removing the residual liquid in the filtrate pipe into the filtrate reservoir and subsequently transferring it to the wash fluid reservoir connected to the washing zone for the penultimate washing step, is included in the process of feeding the filtered RTA precipitate to the discharge zone. In this method, a pressure filter is used to filter a suspension of raw terephthalic acid, and, in addition, when using a multi-stage countercurrent method, washing water is used to wash out the acetic acid-solvent, and by providing a current displacement and drainage, the residual liquid in the filtrate pipe is prevented from entering the next zone after the pressure filter is rotated; while the washing efficiency is increased and the amount of washing water is reduced. In the present invention, the filtration and washing processes of raw terephthalic acid are combined in a single pressure filter, so that the process is reduced, the occupied area is reduced, and energy consumption is reduced.
EFFECT: to regulate the equilibrium pressure in the system, a method is used for supplying nitrogen gas to the mother liquid reservoir and a reservoir for the washing liquid.
8 cl, 8 dwg
