Abstract:

To obtain the optimum distribution of liquid holdup or catalyst volume in the reactive zone for the design of a reactive distillation (RD) column considering selectivity targets, a design and optimization framework based on the combination of exergy loss analysis and process simulation were proposed. An exergy calculation model was established, including both physical and chemical exergy values, according to which the causes of exergy loss could be revealed with insights that provided the evolutionary direction of optimization. By linking the reaction volume distribution with exergy loss, the design of a reactive distillation column with the minimum reboiler heat duty could be accomplished by using the proposed optimization methodology. The proposed methodology was validated by the application to a reactive distillation column for producing ethylene glycol (EG) by hydration of ethylene oxide (EO). The optimized reaction volume distribution could reduce total energy consumption by 18%, compared with the commonly used even reaction volume design. In addition, the effect of energy saving obtained in this work was better than that reported in literature.

Key words: exergy, reactive distillation, optimal design, ethylene glycol

摘要：

针对以选择性为主要目标的反应精馏塔设计中反应段塔板上反应体积或催化剂的分配问题,提出一种基于热力学(火用)损失分析和流程模拟计算相结合的优化设计策略。为了深层次分析反应精馏塔板上(火用)损失的原因并为制定调优方向提供理论依据,将塔板上的总(火用)损失区分为物理(火用)损失和化学(火用)损失两部分并分别进行计算。在此基础上,将建立的(火用)损失计算方法和流程模拟技术相结合,将反应段塔板上的反应体积的分配和对应的(火用)损失分布相关联,以再沸器热负荷最小为目标,通过建立的方法对反应体积的分配逐步调优,可实现反应精馏塔的优化设计。方法的有效性通过环氧乙烷水合制乙二醇反应精馏体系进行了验证。结果表明,与普遍采用的塔板上等反应体积分配的设计方法相比,通过本文建立的优化分配方法,可使系统的能耗降低18%以上,同时结果优于文献值。

关键词: (火用), 反应精馏, 优化设计, 乙二醇