Acetic Acid Dehydration via Continuous Process

In Chapter 9, three candidate acetates were studied in detailed process simulations to determine the best entrainer for this system. The three candidate acetates considered were ethyl acetate, isobutyl acetate, and n-butyl acetate. Rigorous process simulations were performed to find the optimum design and operating conditions of these three entrainer systems. In each entrainer system, the total annual cost (TAC) was used as the objective function to be minimized. From a comparison of the minimized TAC, the isobutyl acetate was selected as the best entrainer with the lowest TAC and operating utility cost. 

2 Operation and Control of Heteroazeotropic Batch Distillation Column 

According to Skouras et the operation of the heteroazeotropic batch distillation 

Mode 1. With this operation mode, the mixture is separated by distillation to recover the heteroazeotrope in the decanter. After the distillation step, the heteroazeotrope splits into its two immiscible phases the entrainer-lean phase and the entrainer-rich phase. Thus, Mode 1 may be viewed as a hybrid process that is a combination of two different separation methods (distillation and liquid-liquid split) operating sequentially. 

Mode 2. With this operation model, the mixture is separated by distUlalion to obtain some of the heteroazeotrope in the decanter, and the liquid-liquid split takes place during distillation with withdrawal or accumulation of the entrainer-lean phase and reflux of aU or part of the entrainer-rich phase. A start-up period is needed for Mode 2 as stated in Skouras et al., where all the mixed phases are refluxed. In our study, this Mode 2 operation will be used to combine two different separation methods (distUlation and liquid-liquid splitting) simultaneously. The batch operating sequence was further modified to combine the start-up period with the next batch operating step to save the total batch time. 

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