聚乙烯醇回收工段醋酸甲酯和甲醇的分离工艺研究

Study on The Separation Processes for Methyl Acetate and Methanol in Alcoholysis Mother Solution Recovering Section of Polyvinyl Alcohol

聚乙烯醇醇解液中甲醇和醋酸甲酯是含量最高的两个组分,二者在蒸馏过程中形成最低共沸物,无法采用普通精馏方法分离。蒸馏过程中加入水做萃取剂,能破坏二者的共沸作用,实现有效分离。本文采用过程模拟软件Aspen Plus对醋酸甲酯和甲醇分离的两塔萃取精馏流程和一塔萃取精馏流程进行了模拟研究。模拟结果表明,对于年产10万吨PVA装置产生的醇解液,采用一塔流程相对二塔流程节能23.6%,但萃取水加入量会由35000kg/h增大至62000 kg/h。总的来说,两种流程各有优缺点,在实际运用过程中,应根据装置建设地点的能源和资源特点进行合理选择。

Minimum azeotrope can be formed between methanol and methyl acetate which are the major components in polyvinyl alcohol alcoholysis mother solution. And water can destroy the azeotropy. In this paper,process simulation was carried out for two extract distillation process for separating methyl acetate and methanol.One was a single column process and the other was a two-column process. The simulated results showed that23.6% energy cost can be saved for the plant of 100 000 tons PVA per year if a single column process is employed instead of two-column process. However, the amount of extract water would increase from 35 000 kg/h to 62 000 kg/h as single column process is employed. It can be concluded that each process have its advantages in different aspects. Selection should be made according to the situation of energy and resources in the place where the plant would be constructed.