Background: Economically recovering valuable cyclohexane and sec-butyl alcohol from wastewater is an important industrial problem worthy of research and investigation. The available separation flowsheet in open literature was a heat pump assisted four-column scheme combining heterogeneous azeotropic and extractive distillation. However, the above design achieves significant energy saving at the cost of huge capital investment and increased operational complexity involved in the compression system. The purpose of this paper is to develop an improved configuration for separating the ternary system without using the expensive compression system, and it can also significantly improve the economics.

Methods: The core design concept of our proposed three separation flowsheets is to fully utilize the advantage of the heterogeneity of the ternary system by introducing the fresh feed into a decanter for natural liquid-liquid splitting and innovatively applying a direct-contact heat exchanger to preheat the fresh feed. Besides, the technologies of dividing-wall column, side-stream extractive distillation and heat integration are also integrated to the heterogeneous azeotropic and extractive distillation for further energy saving.

Significant findings: In comparison with the existing design, our final proposed heat-integrated heterogeneous distillation process with two dividing-wall columns can significantly save energy consumption 24.5%, total annual cost 43.6% and CO₂ emission 13.2%.

背景：从废水中经济地回收有价值的环己烷和仲丁醇是一个值得研究和调查的重要工业问题。公开文献中可用的分离流程是热泵辅助四塔方案，结合了非均相共沸和萃取蒸馏。然而，上述设计以巨大的资本投资和压缩系统所涉及的操作复杂性增加为代价实现了显着的节能。本文的目的是开发一种用于分离三元系统的改进配置，而不使用昂贵的压缩系统，并且还可以显着提高经济性。

方法：我们提出的三种分离流程的核心设计理念是充分利用三元体系的异质性优势，将新鲜原料引入滗析器进行自然液液分离，并创新性地采用直接接触式换热器进行预热。新鲜的饲料。此外，将分壁塔、侧流萃取精馏和热集成技术集成到非均相共沸萃取精馏中，进一步节能。

重要发现：与现有设计相比，我们最终提出的具有两个间壁塔的热集成非均相精馏工艺可显着节省能耗 24.5%、年总成本 43.6% 和 CO ₂排放量 13.2%。