Rigorous simulation optimisation

Keywords Bio-ethanol Purification Plant, Evolutionary Optimisation, Conceptual Design, Rigorous Simulation. 

Consult the designer and check the feasibility of the separation method by rigorous simulation. If the design is not feasible go back to the point (4) and select another split. If the split is acceptable, find the component distribution in the product streams. Do not optimise the design at this stage. 

The benefits captured by optimisation are very process-specific. They can match or exceed those captured by constraint control or they can be a very minor addition. The case illustrated in Figure 13.10 is one where a rigorous simulation-based optimiser would not be justified but perhaps a much lower cost empirical technique, capturing a portion of the available benefits, might be worthwhile. Since the choice of technology and implementer are likely to be influenced by the scope of the project then it is important to decide upon this first. 

The process model was built using PETROX, a proprietary sequential-modular process simulator from PETROBRAS. The simulation comprises 53 components and pseudocomponents and 64 unit operation modules, including 7 distillation columns and a recycle stream. All modules are built with rigorous, first-principles models. For optimization applications, PETROX was linked to NPSOL, an SQP optimisation algorithm. 

The methodology was tested with an example involving the optimisation of a crude distillation unit, using the first-principles models of a sequential-modular process simulator. The solution of the corresponding optimisation problem with this rigorous model required considerable computational effort. 

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