Comparison of stabilizing control structures for four-product Kaibel column

Dividing wall column (DWC) is a promising process intensification technology of distillation. Researchers have been investigating different control structures for different DWC configurations. However, research on control of the four-product Kaibel column is relatively scarce. The focus of this paper is to investigate different control structures of the four-product Kaibel column. The separation of n-pentane, n-hexane, n-heptane and n-octane is used as a case study of control structure selection in this paper. Three control structures are studied: control structure with fixed split ratios (CS1), control structure with an active liquid split (CS2) and control structure with an active vapor split (CS3). CS2 and CS3 are able to stabilize the process and let the product compositions return near the set points. The dynamic performances of the last two proposed control structures show that they are able to handle feed disturbances. This work demonstrates that traditional single-loop PID control is able to handle disturbances inserted into the four-product Kaibel (dividing wall) column.