Control Structure Selection for Dividing Wall Distillation Columns

Abstract

Chemical processes require extensive energy and capital cost to produce massive products because they are the typical mass production industry. Distillation process plays an important role in purifying products and consumes significant amount of energy. As the energy cost increases sharply, it is important to reduce energy consumption and increase productivity in distillation processes. As an alternative for energy saving in distillation processes, the Petlyuk column was proposed in 1950s. The Petlyuk column can reduce energy consumption by thermal integration of two columns. However, the Petlyuk column has strong interaction between two columns due to thermally integrated two columns. To solve this problem and reduce capital cost of the Petlyuk column, Dividing Wall Column (DWC), which is conceptually same as the Petlyuk column, has been developed by installing a vertical wall in the middle part of the column. However, industry has been hesitant to use DWCs because DWCs have control and operation problems. Many literatures have been published to enhance the lack of understanding for DWC control and operation problems. Even though these contributed to understanding DWC control and operation problems, general knowledge on the dynamic behavior of a DWC is still lacking because these studies focused on specific processes and materials. Therefore, it is necessary to establish a general design standard for control structure design of DWCs and it requires that knowledge on the dynamic behaviors of DWCs.