Feasible regions for azeotropic and reactive distillation systems.

摘要

Reactive distillation is a multifunctional process that integrates reaction and separation inside a single piece of equipment. Although simultaneous reactive separation processes offer potential opportunities to improve capital productivity and reduce operating costs, the design of these integrated units is still inadequately understood because of the complicated interactions between reaction and separation. Systematic methods for generating reactive distillation design alternatives have been slow to evolve.; This thesis develops process synthesis techniques for reactive distillation columns by applying the theory of generalized difference points. One key idea motivating this work is that the behavior of any complex column can be represented as a combination of non-reactive, reactive, side feed, and side draw column sections. An approach known as feasibility analysis is used to identify all possible composition profiles, or design alternatives, for each section type. The region of composition space containing all possible profiles over the full range of operating conditions is called the feasible region. Boundary identification is key to defining these regions and involves determining the extreme operating conditions in a section.; Feasible regions for non-reactive sections are discussed to correct an exception to the previously identified bounds in the literature. Based on the properties of reactive section profiles and stability analysis of reactive fixed points, extreme policies for reaction distribution are recognized as the feasible region bounds for reactive sections. In analogy, extreme policies for side stream distribution represent the bounding conditions in side feed and side draw sections. Three examples are used to illustrate how feasible regions enable systematic generation of reactive distillation design alternatives. It is shown that feasibility analysis complements both iterative and optimization-based design strategies.