The invention relates to a method and a device for refining
caprolactam. The device comprises a stripping
tower, a hydrogenation
tower, a triple-effect
evaporator, a
dehydration tank, a concentration
buffer tank, a No. 1 climbing film
evaporator, a No. 2 climbing film
evaporator, an
evaporation and condensation tank, a light component removal
tower and a heavy component removal tower.
Amide oil is subjected to caustification and extraction processes to remove most of byproducts, and a separated
caprolactam water solution is subjected to
benzene stripping, hydrogenation, triple-effect
evaporation, concentration and
dehydration processes and then enters the concentration
buffer tank. Alkali is added into the
buffer tank for performing alkali treatment, and the
caprolactam water solution after alkali treatment enters the climbing film evaporators for climbing film
evaporation. Residues after evaporation return into a
crystallization device for treatment. The caprolactam water solution evaporated by climbing film evaporation enters the light component removal tower and the heavy component removal tower for rectification to obtain a caprolactam product. The climbing film evaporators are used for replacing thin film evaporators, and the alkali treatment process is performed in the concentration buffer tank in advance, so that the
corrosion problem of the evaporators is solved; meanwhile, the alkali
distillation process in an alkali tower is canceled, the process flow is simplified and the
energy consumption and the production cost are reduced.