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The chemical industry has historically favored increasingly larger plant designs to lower production costs for bulk chemicals and petrochemical products. The drawbacks of scale-up chemical plants, such as the growth in emissions and by-products treatment, have become more relevant due to tighter environmental regulations and more expensive energy resources. Process intensification (PI) is based on the search for radical improvements in chemical processing, substantially decreasing equipment volume, energy consumption or waste formation. Most of the developments in process intensification are based on experimental work while the development of a systematic approach for process intensification is still in its incipient stages. This dissertation proposes to address this problem by applying the IDEAS framework as a systematic tool for process intensification. The search for intensified solutions in chemical processes using nonlinear models can drive a nonlinear synthesis process to stop in one of the multiple local optimal solutions. In the IDEAS approach, nonlinear chemical processes are linearized through the induction of an infinite number of states, forming a convex system that has a guaranteed global optimum. IDEAS based formulations generate an infinite linear program (ILP) which has its infimum value approximated by a series of finite-dimensional linear programs of ever increasing size. Reactive distillation systems are natural candidates for process intensification due to the prompt removal of the product from the reaction by the separation process, usually leading to higher conversion, smaller processing systems, and reduced volumetric footprint. The rigorous identification of the intensification limits for ternary reactive distillation systems through the application of the IDEAS framework is presented in chapter 1, featuring the tradeoff between the system’s total capacity (a surrogate for size) and its total reactive holdup (a surrogate for catalyst use). In chapter 2, the tradeoff between the network size, captured by the total capacity variable, and the total utility consumption in a ternary reactive distillation system is investigated. The irreversibilities of reactive distillation systems are investigated in chapter 3 through the solution of the minimum entropy generation rate problem, and its relation to the capacity is assessed. In chapter 4, the potential benefits related to the use of multi-pressure reactive distillation systems are investigated for a ternary azeotropic mixture. The application of the IDEAS approach in problems involving a higher dimensionality in investigated in chapter 5 with the support of a column generation procedure, applied to solve the large-scale linear programming resulted in the assessment of the reactive separation of quaternary azeotropic mixtures. |
