High computational loads, time-consuming convergence, and simulation crashes are common when using process simulators for flowsheet optimization. In this paper, by replacing the large-scale physical process simulations by surrogate models,the optimization time and computational load are reduced significantly along with maintaining the accuracy and reliability.A gas-to-liquids (GTL) plant was used as a large-scale process plant case study. The multi layer perceptron neural network (MLP-ANN), radial basis function neural network, support vector machine, and adaptive neuro-fuzzy inference system models were selected as alternative surrogate models. These alternatives were investigated for implementation of the self-optimizing control procedure on the above case study to find the best individual and combined self-optimizing controlled variables. The MLP-ANN surrogate model showed the best performance in predicting the optimum points and for selecting the best self-optimizing CVs. In fact, it even performed better than using the full process simulator.

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