A comparison of flowsheet solving strategies using interval global optimisation methods

Abstract This paper investigates an approach to process optimisation that allows construction of flowsheets in modular systems that can then be optimised using interval global optimisation methods based on branch and bound methods. The modular flowsheets are constructed with generic unit modules that can provide the inerval bounds, linear bounds and derivative bounds using extended arithmetic types. Modular flowsheets are convenient and modular flowsheeting systems very popular. The simultaneous modular approach along with equation-based methods have been used to optimise three case studies. The modular approach has advantages but when optimising there is a price to pay for this. More bounding steps are required resulting in higher computation times although in the case of the water network problem, the most nonlinear of the problems, the price was small.