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Selecting Decision Variable for a Plant-wide Optimization  

Jeong, Changhyun (School of Chemical and Biological Engineering, Seoul National Universty)
Jang, Kyungsoo (School of Chemical and Biological Engineering, Seoul National Universty)
Han, Chonghun (School of Chemical and Biological Engineering, Seoul National Universty)
Publication Information
Korean Chemical Engineering Research / v.46, no.4, 2008 , pp. 714-721 More about this Journal
Abstract
Chemical plants which consume lots of energy are not operating in the best conditions due to their own peculiar nonlinearity, instability, and diverse disturbances. In order to improve this, the plant wide optimization was performed. It is important to select the most appropriate number of decision variables which strongly affect the operating cost because there are too many decision variables which economically have an effect on plant wide. For instance, if all decision variables which can economically affect are applied in optimization and then the result of the optimization is applied to operation, a lot of operating conditions should be going to be changed. As a result of changing a plenty of operating conditions, the cost of the change will absolutely increase. Thus, in this study, the method of selecting the most appropriate decision variables which can influence on saving operation costs was presented in order to optimize plant wide. TPA (Terephthalic-acid) plant is considered as a case study. In other word, after modeling, the most proper decision variables was selected by examining the degree which decision variables influence on operating costs through sensitivity analysis. In TPA process, the three decision variables were selected by the presented method in this study. Then the plant was optimized by selected the decision variables. Consequently, it was seen that the plant are expected to save the 350 million won of energy annually without additional investment for facilities or remodeling of the plant.
Keywords
Plant-Wide Optimization; Sensitivity Analysis; Variable Selection; TPA Process;
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