The invention discloses a water-rich
solvent classification utilization emission reduction
system for preparing
terephthalic acid, which comprises a plurality of units, such as oxidation reaction, rectification
dehydration, oxidation and purification
filtration,
solvent stripping, multi-effect
distillation and the like. According to the
system, through the optimized configuration of materials, water-rich solvents with different levels of
acetic acid concentration are classified and utilized, and on the premise of ensuring product quality and effectively utilizing the reaction heat, the use amount of
fresh water is greatly reduced and the
organic matter content in a discharged liquid is reduced. The key technology lies in that: (1) a
dehydration unit is provided with a three-stage rectifying column, the water-rich
solvent produced by each unit in the oxidation and refining process is re-circulated to the rectifying columns according to a concentration matching rule, and the water-rich solvents obtained by rectification are respectively used for oxidation filter washing, refining filter washing,
exhaust gas spraying and the like as required by different
acetic acid concentrations; (2) self-produced low-pressure steam of the
system is utilized for multi-effect
distillation of the discharged liquid, thereby fully recovering
acetic acid in the discharged liquid, and reducing systemacetic acid consumption.