【作者】 骆淑莉；

【导师】 白鹏；

【作者基本信息】 天津大学 ， 化学工程， 2005， 硕士

【摘要】 动态累积循环操作是近年来开发的间歇精馏新型操作方法之一。这种操作方法是由全回流浓缩、出料、无回流充液三个步骤构成,反复循环直至操作结束。同传统的间歇精馏操作方法相比,动态累积循环操作具有控制简便、分离效率高等突出的优点。虽然该操作方法早在20世纪60年代就已经被提出,但目前的研究基本集中在操作方法优化的理论研究上,而缺少对其自动控制和工业化装置的实验研究。特别是传统精馏理论无法涉及的塔内无回流充液阶段的浓度变化问题一直没有得到很好解决,导致了以往动态累积循环操作法的数学模型和模拟计算只能以与塔内真实状况相差很大的简化假设为基础,这严重地阻碍着动态累积循环操作法的进一步发展。本文建立了动态累积循环操作自动控制实验装置,研究了该实验装置的流体力学特性,提出了用两个较小的累积罐进行交替切换的操作方法,在采出产品阶段,通过温度控制累积罐之间的切换,在过渡馏分采出阶段,采用时间脉冲控制过渡馏分的采出。实验也研究了投料浓度、投料体积的变化对实验过程的影响。本文以异丙醇-正丙醇为实验物系对该操作进行的实验研究,结果表明本文提出的操作方式是完全可行的,并使动态累积间歇精馏操作更加紧凑连贯,并且各组分的采出也非常容易实现自动控制。另外本文还对动态累积循环操作的无回流阶段进行了实验研究,分析了不同相对挥发度、不同进料浓度对无回流阶段塔顶浓度的影响。最后本文建立了动态累积循环操作全过程的数学模型,并求解了模型方程。本文模型与文献模型的主要区别在于针对无回流充液阶段,前者考虑了流体力学关系的变化,取消了以往恒摩尔流和恒摩尔持液的简化假设。模拟结果与实验结果的比较表明本文的数学模型能够更准确的模拟动态累积循环操作。更多还原

【Abstract】 Dynamic-accumulation cyclic operation (DACO) is one of the new operating modes of batch distillation. It involves three periods: total reflux, dumping and filling up. DACO has several advantages over conventional operation with high efficiency, energy saving and convenient controlling. It was proposed in the 1960’s and developed rapidly in the 1990’s. However, some theory problems, for example, the fluid dynamics and mass transfer during the filling up period which could not be dealt with in conventional distillation theories has been remained unstudied. And the simulation and mathematical models have to be made based on some assumptions, which are different from the actual situation obviously. Therefore the further development of DACO was restrained in the past years. The models for DACO were established in this paper. The fluid dynamic relations were involved in the models without general assumptions of constant molar liquid flow and constant molar holdup. It is the main difference between our models and literature’s. Calculation results were compared with experimental results. It shows that our models are coincident with the experimental data. The alternation between two relatively small accumulation drums was proposed in the thesis, in which the alternation of accumulation drums was realized via temperature. The viability of controlling the transitional fraction sect of DACO by time impulse was demonstrated by experiments too. Thus, the operation become more successive and compact, and the automatic control of dynamic-accumulation batch distillation was made easy. Isopropyl alcohol and n-Propyl alcohol was used to conduct the experimental study of this operation. Experiments about filling up were carried out in the laboratory batch distillation column. Experimental results were in good agreement with simulation results.更多还原