2016-Simultaneous Optimization of the Design and Operation of Batch Reactive Distillation Process.pdf

Simultaneous Optimization of the Design and Operation of Batch Reactive Distillation Processes Yu-Lung Kao and Jeffrey D. Ward* Department of Chemical Engineering National Taiwan University Taipei 10617, Taiwan ABSTRACT: Simultaneous optimization of equipment design and process operation for batch reactive distillation processes is studied in this work. The minimal total annual cost problem is illustrated with two realistic chemical systems: hydrolysis of methyl lactate and esterification of formic acid. The effect of design and operating variables on total annual cost is investigated. The optimization results suggest that a reflux policy which maintains constant distillate composition can provide nearly optimal operation. The column should be designed with an adequate number of stages so that the batch capacity improvement by further increasing the number of stages is insignificant. Vapor boilup rate should be specified to make the best use of the available operating time, and the optimal vapor boilup rate is primarily affected by the catalyst loading. The insight into the effect of process design variables on design performance is used to develop an efficient algorithm for determining simultaneously the optimal column design and operating policy. 1. INTRODUCTION Batch distillation is a widely used technique for liquid?liquid separation in chemical processes. In a conventional chemical plant, reaction and distillation usually take place in separate units. However, the drive to reduce costs and energy consumption has motivated the study of more efficient alternatives. Combining batch reaction and batch distillation into a single operation unit, batch reactive distillation (BREAD), has the potential to overcome reaction equilibrium and azeotropes and to reduce capital and operating costs. Compared with its counterpart, continuous reactive distillation, batch-wise operation is more flexible and suitable for small scale production, such as for specialty chemicals, fine