Refining process and refining system of caprolactam

Abstract

A refining process includes steps of subjecting crude caprolactam to a first evaporative crystallization and a first solid-liquid separation to obtain a first caprolactam crystal and a first crystallization mother liquor; washing the first caprolactam crystal to obtain a second caprolactam crystal; optionally concentrating the first crystallization mother liquor to perform a second evaporative crystallization and a second solid-liquid separation to obtain a third caprolactam crystal and a second crystallization mother liquor; subjecting the third caprolactam crystal to a second washing to obtain a fourth caprolactam; optionally concentrating the second crystallization mother liquor to perform thermostatic crystallization, performing separation to obtain a fifth caprolactam crystal and a third crystallization mother liquor; washing the fifth caprolactam crystal to obtain a sixth caprolactam crystal; and subjecting the second caprolactam crystal to a hydrogenation reaction.