Acetic Acid Recovery via Extractive Distillation

The patent introduces an extractive agent (entrainer) as an intermediary substance that forms an azeotrope with water. This mediator changes the relative volatility between acetic acid and water, enabling separation at lower energy consumption. The entrainer selectively interacts with water to form a low-boiling azeotrope that can be easily separated from acetic acid, thus resolving the close-boiling problem without requiring high reflux ratios or numerous theoretical stages.

The patent changes the physical-chemical parameters of the separation system by introducing a third component (entrainer) that modifies the vapor-liquid equilibrium relationships. This parameter change transforms the difficult separation of close-boiling acetic acid-water into an easier separation involving an azeotropic mixture, thereby reducing the number of theoretical stages and reflux ratio requirements while maintaining effective acetic acid recovery.

By introducing an extractive agent as a mediator, the patent enables more efficient mass transfer and separation. The entrainer's selective interaction with water creates a more favorable separation scenario, allowing the use of fewer and smaller distillation columns while achieving the same recovery efficiency. This reduces both the number of theoretical stages required and the physical size of equipment needed.

The introduction of the entrainer changes the separation parameters, improving relative volatility and enabling more compact equipment design. The modified vapor-liquid equilibrium allows for smaller column diameters, fewer trays, and reduced overall equipment footprint while maintaining the required separation performance and acetic acid recovery rates.

The extractive agent acts as a mediator that facilitates separation at lower energy input. By forming an azeotrope with water, the entrainer enables the distillation process to proceed at lower reflux ratios and with fewer theoretical stages, directly reducing steam consumption. The mediator's presence creates a more energy-efficient separation pathway that maintains effective acetic acid recovery while minimizing thermal energy requirements.

The patent changes the thermodynamic parameters of the system by introducing the entrainer, which modifies the energy requirements of the distillation process. This parameter change reduces the heat duty required per unit of acetic acid recovered, lowering steam consumption and associated operating costs while maintaining the necessary separation efficiency and recovery rates.