带中间换热器的热泵精馏隔壁塔的综合设计与优化研究

Dividing wall column (DWC) does not always have high thermodynamic efficiency for the reasons that all the heat input is done at the highest temperature level and all of the heat removal is done at the lowest temperature level. At the same time, vapor and liquid transfers between different sections produce an unavoidable excess of vapor or liquid in some of them, increasing both the operating and investment costs. In this project, a vapor recompression dividing wall column with intermediate exchanger is suggested, for the aims of improving the thermodynamic efficiency and spreading the application scope of dividing wall column. The effects of mixtures property on energy saving efficiency and the excess of vapor(liquid)of dividing wall column are investigated, then different types of dividing wall column with intermediate exchanger and different types of vapor recompression dividing wall column are designed and optimized. On these bases, the vapor recompression dividing wall column with intermediate exchange is explored. Furthermore, its structure and operating parameters are optimized to get the minimum total annual cost(TAC).Finally the energy saving efficiencies and TACs of above types of dividing wall columns are compared and evaluated.

常规隔壁塔所需加热量全部由温度最高的塔底再沸器提供，所需冷却量全部由温度最低的塔顶冷凝器提供，从而造成隔壁塔较大的有效能损失。同时，塔段间较强的热耦合会使塔内产生剩余汽（液）相流量，从而使能耗和投资费用增加。针对以上问题，本项目提出了一种带中间换热器的热泵精馏隔壁塔的设计，将热耦合精馏、热泵精馏和带中间换热器精馏的节能优势综合到一起，从热力学第一定律和第二定律两方面提高隔壁塔的节能效率。本项目考察了物系特性对常规隔壁塔节能效率和塔内剩余汽液相流量的影响；分析了带中间换热器隔壁塔的多种实现方案；设计优化了热泵精馏与隔壁塔的综合流程；将中间换热器和热泵精馏进行合理组合，建立了带中间换热器的热泵精馏隔壁塔的综合优化流程，分析和比较了不同分离物系和进料组成下，该综合流程的节能效率和投资费用情况。最后对主要节能方案进行了比较和评价。

本项目将热耦合精馏、热泵精馏和带中间换热器精馏的节能优势综合到一起，提出了带中间换热器的热泵精馏隔壁塔流程，开展了相关优化设计研究。首先研究确定了从常规隔壁塔到带中间换热器的热泵精馏隔壁塔的设计方法和优化步骤。其次将各类型热泵精馏隔壁塔应用到分离实例中，研究所提出的热泵隔壁塔的节能特性。再次，提出了热泵系统与隔壁塔的深度热集成流程方案，研究了该类流程的设计与优化方法，通过分离实例研究了热集成流程的节能特性。最后对各流程的节能特性做了梳理与比较，分析了各流程的适用条件和应用范围。研究成果拓展了精馏节能技术的研究思路，对化工行业的节能减排做出了应有贡献。