(290c) Plantwide Control of a Complex Process Involving a Reactive Distillation Column

In the conventional chemical process industries, reaction and seperation are usually carried out separately in multi-unit processes. However, increasing economic and environmental considerations force the industry to alternative designs based on process intensification. Nowadays, reactive distillation columns combining reaction and seperation units into a single vessel is one of the attractive examples of process intensification.

This also brings along an increasing concern on the design and control of the reactive distillation columns. The potential for process intensification makes the reactive distillation columns the subject of many papers in recent years. The vast majority of these papers deals with the steady-state design and the dynamic behaviour of the individually operating reactive distillation columns. However, real industrial chemical processes typically contain several reaction steps and multiple recycle streams. Thus, there is a lack of knowledge on the plantwide control of multi-unit complex processes involving reactive distillation columns.

In this study, a simplified version of a real complex industrial process is utilized as the test case [1]. This  plant contains two reaction steps, three distillation columns, two recycle streams and six chemical components. Since the chemistry and volatilities are suitable, combining the second reaction step and the third distillation column into a reactive distillation column is possible. By elimination of two reactors in series, the new process consists of a reactor, two distillation columns, one reactive distillation column and two recycle streams.  

The aim of the study is to investigate the dynamic controllability of this multi-unit process involving a reactive distillation column. After replacing two reactors and one conventional distillation column with a reactive distillation column, several effective plantwide control strategies will be developed and tested.

[1] Luyben, M.L., Luyben, W.L., Design and Control of a Complex Process Involving Two Reaction Steps, Three Distillation Columns, and Two Recycle Streams, Ind. Eng. Chem. Res., 1995, 34, 3885-3898.