New trends in optimization-based approaches to process synthesis

A systematic procedure presented in this paper draws distillation column configurations to separate an ideal to near ideal n-component mixture into n product streams with each enriched in one of the components. The method synthesizes all feasible basic configurations using n-1 distillation columns with each column having only a condenser at the top and a reboiler at the bottom. It also generates all feasible thermally coupled schemes with classical two-way liquid and vapor communication between the distillation columns. The method is simple and easy to use. The advantage of such a method is that it could be incorporated in a search algorithm to systematically find an optimum distillation scheme for a given application.

Synthesis of multicomponent distillation column configurations

In this paper a new method is presented which will enable engineers toselect better heat integrated distillation systems quickly and easily. The keyto this method is making the assumption that OAT, the product of thecondenser or reboiler duty and the temperature difference between the reboilerand condenser, is constant for a single distillation task over a wide range ofpressures. Using this assumption and the principles of multieffect distillation,a lower bound on the utility use for single distillation tasks and for distillationsequences is readily calculated for designs involving simple two productcolumns that may or may not be multieffected. This paper also describesmethods which can be used to synthesize distillation systems which approachthese bounds. Finally, an algorithm is presented which develops the least costdistillation system for separating a multicomponent feed. The methods in thispaper are illustrated with a five component example problem.UNIVERSITY LIBK/kRIESCARNEGIE-MELLON UNIVERSITYPITTSBURGH. PENNSYLVANIA 15?13

A Simple Synthesis Method Based on Utility Bounding for Heat‐Integrated Distillation Sequences

The synthesis of distillation-based separation systems

Hybrid separation processes combine different separation principles and constitute a promising design option for the separation of complex mixtures. Particularly, the integration of distillation with other unit operations can significantly improve the separation of close-boiling or azeotropic mixtures. Although the design of single-unit operations is well understood and supported by computational methods, the optimal design of flowsheets of hybrid separation processes is still a challenging task. The large number of operational and design degrees of freedom requires a systematic and optimization-based design approach. To this end, a structured approach, the so-called process synthesis framework, is proposed. This article reviews available computational methods for the conceptual design of distillation-based hybrid processes for the separation of liquid mixtures. Open problems are identified that must be addressed to finally establish a structured process synthesis framework for such processes.

Conceptual design of distillation-based hybrid separation processes.

The problem of synthesizing an optimal multicomponent separation system which is energy integrated is solved by a combined decomposition and dynamic programming technique.

Dynamic programming is an optimization technique which allows the solution by decomposition of a multistage or serial optimization problem. Whenever the special serial structure is absent, again decomposition can be tried, but in this case it is by no means obvious how to decompose effectively the given problem into subproblems. In this paper the nonserial problem of synthesizing an energy integrated separation system is solved by decomposing the original problem so that a serial structure results.

Kenneth A. Van Wormer

Papers

Synthesis strategies for multicomponent separation systems with energy integration