| Summary: | 碩士 === 國立清華大學 === 化學工程學系 === 94 === The separation of water and acetic acid is one of high energy consuming processes. This research studies a various strategies of energy saving in such a commercial process which contains impurities of MA and PX. Since the normal boiling points of water and acetic acid are very close, the best way to separate them is to use an entrainer, iso-butyl acetate in this case, to change their relative volatility. Using heterogeneous azeotropic distillation requires much less energy than the conventional distillation.
We also propose the newly developed technology, thermal coupled distillation column, to separate three components. The study results show that the thermal coupled distillation column, divided wall column, not only reduce the capital cost, but also save energy as high as 28% compared with the conventional column.
The manipulated variables are entrainer makeup and reboiler duty used to implement two temperature control loops to obtain the products purities of acetic acid dehydration column. SVD analysis is also used to choose two controlled stages, and we find that the set point of the controlled stage isn’t needed to be changed under entrainer inventory control. However, the set point of the other stage controlled by reboiler duty is needed to be changed, thus we use cascade control to solve this problem. About DWC, we use SVD and RGA to build the control strategy and we can obtain the products purities under these three temperature control loops.
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