Process Design Approach for Reactive Distillation Based on Economics, Exergy, and Responsiveness Optimization

Abstract

The interactions between economic performance, thermodynamic efficiency, and responsiveness in reactive distillation process design are explored in this contribution. This motivation is derived from taking a sustainable life span perspective, where economics and avoidance of potential losses of resources (i.e., mass, energy, and exergy) in process operation over the process life span are taken into consideration. The approach to reactive distillation column design involves defining a generic lumped reactive distillation volume element and the development of rigorous dynamic models for the behavior of the element. As an extension of conventional existing models, this model, which is used as a standard building block, includes entropy and exergy computations. Three objective functions are formulated, which account for the process performance regarding economy, exergy loss, and responsiveness. A fundamental understanding of the strengths and shortcomings of this approach is developed by addressing various case studies: (i) steady-state simulation of a classical MTBE design based on economics only, useful as a reference case; the multiobjective optimization of a MTBE reactive distillation column with respect to (ii) economics and thermodynamic efficiency; and (iii) economics, thermodynamic efficiency, and responsiveness. Structural differences and dynamic responses are identified between the optimized and classical designs to stress the importance of considering exergy and responsiveness criteria. Thus, the classical (economics-driven) design is compared to a green (economicsand exergy-driven bioptimized) design. The green design produces less entropy than the classical one, while being marginally less attractive from an economic standpoint. The bioptimized design has an improved closedloop performance compared to the classical design, keeping the same control structure and settings. It is concluded that incorporating both economic-and exergy-related objectives in the unit design results in a process with better closed-loop performance and reduced exergy loss.

Continuous-Molecular Targeting for Integrated Solvent and Process Design

“…Process-wide objective functions could reflect aspects of cost, energy, or second-law efficiency. Even dynamic aspects such as process responsiveness could be taken into account in the process design as suggested in the work of Almeida-Rivera and Grievink . Different objectives can be employed to study the implications on solvent selection and process design.…”

Conceptual methods for synthesis of reactive distillation processes: recent developments and perspectives

“…This involves considering factors such as investment costs, operating costs, energy consumption, environmental impact, exergy and responsiveness to balance various objectives and make decisions. 140,141 Results of function design methods Reactive distillation with pre-and/or side reactors. Function-based design with PSE methods has resulted in several options that need further detailed design on configuration and parameter setting.…”

“…Based on the identified functions in the process and their interactions, options for integrating the function units need to be evaluated by optimization techniques. This involves considering factors such as investment costs, operating costs, energy consumption, environmental impact, exergy and responsiveness to balance various objectives and make decisions 140,141 …”