Distillation is a thermal separation unit operation that separates liquid mixtures relying on boiling point and volatility differences. High-purity target products are obtained through partial vaporization of feed liquid and subsequent vapor condensation. Four mainstream technical forms including conventional distillation, reactive distillation, extractive distillation and vacuum distillation are extensively adopted across petrochemical, fine chemical and pharmaceutical sectors. Though mature, distillation remains the most energy-intensive separation process, which spurs continuous technical upgrades such as process intensification, heat integration and advanced tower internals to cut energy consumption and boost separation efficiency.