Packed Tower Modeling with Least Squares, Genetic Algorithm and Design of Experiments Methods

Document Type : Research paper

Authors

Department of Chemical Engineering, Faculty of Engineering, Arak University, , Arak, Iran

Abstract

Objective: Design of Experiments is a useful tool for reducing the number of experiments and, consequently, lowering costs; moreover, it provides a model that is valid within the experimental range. Additionally, modeling is used as a method for predicting system behavior and saving costs. The aim of this research is the modeling of experiments conducted in a packed distillation column and the prediction of the Height Equivalent to a Theoretical Plate (HETP).
Materials and Methods: This research is based on available experimental data for a packed distillation column. The test materials were cyclohexane and n-heptane. The column was packed with one-inch Pall ring packing, and the experiments were conducted at two pressures of 0.35 bar and 1.65 bar. Among various methods, three widely-used approaches Genetic Algorithm, Least Squares, and Design of Experiments were selected for modeling.
Results: The models obtained by the Genetic Algorithm and Least Squares methods, although having different coefficients, yielded similar results. Regarding the Design of Experiments method, analysis of variance showed that the data were not suitable for analysis; therefore, favorable results were not obtained, because the experiments performed had not been designed on this basis. Modeling with the three methods was expected to produce similar results. The reason for the difference in the Design of Experiments model was the unsuitability of the experimental data.
Conclusion: With using the models provided by the Least Squares and Genetic Algorithm methods, the performance of the packed column can be predicted with acceptable accuracy within the experimental range, and the HETP can be calculated without the need for costly and time-consuming experiments. Furthermore, this study showed that the Design of Experiments method yields reliable results only when the data are collected from the outset according to its principles, such as randomization, appropriate dispersion, reproducibility, etc.

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