Energy Conservation Strategies Of Acetic Acid Dehydration System

Acetic acid is one of the most important organic carboxylic acids, it is often used as organic solvents besides reactants. In most cases, recycling acetic acid in the industrial wastewater has enormous economic value. However, the separation between acetic acid and water is difficult and energy intensive. Due to the high energy consumption of the acetic acid dehydration section in the production of purified terephthalic acid, energy-saving strategy is investigated from two aspects by using simulation software Aspen plus.Firstly, some amount of the methyl acetate is introduced directly into the entrainer recovery column to solve the energy waste problem caused by the accumulation of the methyl acetate in acetic acid dehydration tower. When the methyl acetate in the feed exceeds a certain amount, the proposed technology can decrease the energy consumption of the refiner effectively. Thus the energy consumption can be reduced by more than5%in the two-stage partial condensation process.Secondly, an extraction-azeotropic distillation integration process using the n-butyl acetate both as extractant and entrainer is presented in this paper for the recovery problem of the low concentration of acetic acid. Through the simulation analysis, it is proposed to increase the butanol content in the NBA by5wt%to improve the extraction efficiency. The optimal feed ratio of the extraction column is determined as21%by analysis. Under above conditions, the equipment investment and operating cost in the extraction-azeotropic distillation integration process can be saved by11.4%and20.3%respectively.