Real‐time optimisation (RTO) systems face challenging scenarios in industrial practice, such as incomplete and corrupted process information, uncertain large‐scale mathematical models and numerical optimisation issues. Proper design of RTO structure and robust diagnosis tools are keys for good performance, although they are neglected in commercial RTO software and not fully solved in the technical literature. This article reviews the concepts behind the two‐step RTO approach and suggests performance metrics. It also points out the large list of structural decisions and the consequences of intuitive, experience‐based RTO design choices. The discussed vulnerabilities are illustrated with some simulations and real industrial implementations. © 2012 Canadian Society for Chemical Engineering

Abstract:The proper design of RTO systems' structure and critical diagnosis tools is neglected in commercial RTO software and poorly discussed in the literature. In a previous article, Quelhas et al. (Can J Chem Eng., 2013, 91, 652-668) have reviewed the concepts behind the two-step RTO approach and discussed the vulnerabilities of intuitive, experience-based RTO design choices. This work evaluates and analyzes the performance of industrial RTO implementations in the face of real settings regarding the choice of steady-state detection methods and parameters, the choice of adjustable model parameters and selected variables in the model adaptation problem, the convergence determination of optimization techniques, among other aspects, in the presence of real noisy data. Results clearly show the importance of a robust and careful consideration of all aspects of a two-step RTO structure, as well as of the performance evaluation, in order to have a real and undoubted improvement of process operation.

PFH was associated with a more homogeneous attenuation of alveolar damage across the lungs, although this therapy had more pronounced effects in nondependent zones. PLV showed the opposite pattern, with more important reduction in alveolar damage in dependent lung regions. Interestingly, reduction in alveolar damage with PFH was as effective as with PLV in dependent zones. Our findings suggest that vaporized perfluorocarbon could be advantageous as adjunctive therapy in the treatment of acute lung injury.

Although the use of 5% vaporized perfluorohexane permitted the authors to reduce pressures needed to stabilize the lungs and was associated with better histologic findings than were PLV and GV, none of these perfluorocarbon therapies improved gas exchange or lung mechanics as compared with GV.

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