DYNAMIC SIMULATION STUDIES OF A DIVIDED WALL DISTILLATION COLUMN FOR A TERNARY MIXTURE

Dividing-wall column (DWC) is very attractive as the most energy saving alternative for conventional distillation columns. A DWC encloses a vertical wall that divides the middle section of the column into two parts and contains the pre-fractionator/post-fractionator in the same shell. This column configuration splits both the rectifying liquid coming from the column top and stripping vapor rising from the column bottom, to both sides of the wall. DWC eliminates undesirable mixing near the feed stage in conventional columns, and thus reduces energy required for separation.

Simulation of a DWC and study its control behavior is a challenging task, as it involves numbers of variables. In the present work, simulations study of a DWC for a ternary mixture of Benzene-Toluene-p-Xylene has been presented. The initial design estimates were made using the three shortcut columns. Rigorous simulation of a DWC has been done by Radfrac model of Aspen Plus simulation software, considering a four column structure. The energy requirement for a DWC is effected by the variation of the process parameters liquid split, vapour split and reflux rate. The study of control behavior of the DWC is also presented in the present work. The simulations to study the control of DWC were done using ASPEN dynamics software.