Evolutional Design and Control of the Equilibrium-Limited Ethyl Acetate Process via Reactive Distillation−Pervaporation Hybrid Configuration
2016
Lee, Hao-Yeh | Li, Sheng-Yu | Chen, Cheng-Liang
Ethyl acetate (EtAc) is an important chemical and is normally produced via esterification reaction of acetic acid with ethanol. Due to the thermodynamic limitation of the EtAc esterification system, an energy efficient two-column process which is composed of a reactive-distillation (RD) column and a stripper has been proposed recently1,2 to remove water for yielding high purity EtAc product. Considering recent phenomenal advancement of membrane technology, this study raises a RD–pervaporation (PV) hybrid configuration for producing high purity EtAc with further decreased energy consumption. A side stream with high EtAc purity is drawn from the rectifying section of the RD column, and pervaporation units are applied to remove water for producing high spec EtAc product. The optimized design achieves 13% energy savings compared to the two-column process.2 Based on the optimized RD–PV hybrid process, two different control strategies—the single-point temperature control and the dual-points temperature control—are proposed to examine the performance of rejecting the main disturbances to the process. A lot of simulation tests show that the single-point temperature control structure can handle throughput disturbance but fails to maintain adequate product specification should the acid purity in the feed be lower than a specific value. However, the dual-points temperature control structure can successfully deal with both throughput and feed composition disturbances.
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