Temperature sensor location for the implementation of cascade control schemes in distillation columns: an approach based on multiscale time series analysis

Abstract

Abstract In this work, the application of multiscale analysis to evaluate the sensitivity of the dynamic responses of the trays in a distillation column exposed to external disturbances is explored. This sensitivity allows for the identification of the tray where the temperature sensor improves the performance of a composition-temperature type cascade controller. To implement the proposed methodology, synthetic time series are generated for each plate of the column, which is subsequently analyzed using the multiscale rescaled range (R/S) analysis. Three case studies were evaluated (binary mixtures, azeotropic mixture and ternary mixture), finding that the highest values of the Hurst exponent correlate with the areas of greatest sensitivity of the column. To corroborate this result, a composition-temperature cascade control scheme was implemented, evaluating the temperature sensor in each plate of the column, identifying that the zone of greatest sensitivity determined with the multiscale analysis corresponds to the best performance of the controller. Therefore, our results show that the proposed methodology represents an easy-to-implement alternative that provides information on the most suitable zone for the placement of temperature sensors to improve the performance of cascade control in a pre-designed distillation column.