Optimisation of thermally coupled distillation sequences with side columns

摘要

An approach for the optimal design of thermally coupled distillation sequences (TCDS) with side columns is presented. Both systems with side strippers and side rectifiers are considered. The design task is formulated as a non-linear programming problem that uses shortcut methods for the thermally coupled systems. The application of the optimisation model provides the tray structure and operating conditions that minimise the total annual cost of the system, which includes capital investment and utilities costs. When the shortcut designs were validated through rigorous simulations, one major feature of the resulting TCDS structures was that they properly located the interconnecting tray for the thermal coupling, thus providing energy-efficient designs by minimising remixing effects. A comparison with reported results for the design of TCDS with side columns from the use of a mixed-integer non-linear programming model is also presented.