Abstract
In a polyvinyl alcohol (PVA) plant, reaction stoichiometry indicates that equal molar of methyl acetate (MA) is generated for every mole of PVA produced. One possible way is to convert MA back to acetic acid and methanol, which are raw materials of PVA plant, using MA hydrolysis. Tough environmental regulations, intense competition, and expensive fossil energy use have prompted efforts to retrofit the existing hydrolysis processes to reduce their energy requirements. Thus, in this paper, a novel dual-effect side stream reactive distillation was proposed to reduce the energy requirements. The design and optimization procedures using the response surface methodology, which can handle both structure and operating variables simultaneously, were employed for retrofit design with particular emphasis on simple and efficient efforts. This was found to be a simple and effective optimization methodology for a complex system. The simulation work was performed using simulator Aspen Plus V8.6. Furthermore, carbon dioxide (CO2) emissions were considered and calculated when retrofitting an existing MA process to the proposed sequence. As a result, the proposed retrofitted sequence resulted in operating cost savings of 54% compared to the existing sequence. The short payback period of 2 months and reduced CO2 emissions of up to 52% showed that the proposed sequence is an attractive option for retrofitting in industrial implementation. This sequence can be also employed for grass-root designs.
