Distillation Design and Control Using Aspen Simulation

This book uses the commercial simulator Aspen Plus to develop rigorous simulations of single distillation columns and sequences of columns. Methods are illustrated for designing the economic optimum distillation column from a steady-state standpoint. Total annual cost, which includes both capital and energy costs, is used as the objective function to be minimized. Other issues such as robustness to disturbances and sensitivity to uncertainties in physical properties, tray efficiencies and market requirements are also considered. Another unique feature is coverage of the design and control of petroleum fractionators, which is non-existent in any design books. Aspen Dynamics are then used to explore the dynamics of these designs and to develop effective control structures. The new edition updates and expands on the first edition and adds new chapters on the divided wall column a more widely applied method and carbon dioxide capture from stack gas. Also discussed is the use of dynamic simulation to study safety issues (high pressure and temperatures) in the event of operating failures (loss of cooling water), an update on the discussion of Aspen Plus analysis tools for ternary distillation columns and azeotropic separation, and a discussion of control structures and process configurations for handling the very significant column turndowns (very low feed flowrates) required in chemical plants coupled with power generation processes or inherently intermittent "green" energy sources (solar and wind).