Simulation and Energy-Economic Analysis for Separation Process of Acetic Acid Waste Liquid with Low Water Content

The acetic acid production process can produce a considerable amount of waste liquids. Thus, recycling acetic acid from those liquids is one of the key approaches for acetic acid industry to help achieve energy conservation, emission reduction, and sustainable development. For the separation and recovery of acetic acid waste liquids with low water content, four different separation simulation processes, namely, the conventional distillation, extractive distillation, azeotropic distillation, and heat pump distillation, are established, and the energy consumption and economy of these four separation processes are analyzed and compared with each other comprehensively. Taking a practical acetic acid production industry as an example, the strengths and weaknesses of the four methods proposed in this paper are investigated. The results indicate that all these four separation processes are capable of recovering acetic acid products that meet the requirements of GB/T 1628—2020. In terms of energy consumption and utility cost, the energy consumption of the heat pump distillation is the lowest among these four separation processes, while that of the extractive distillation is the highest. Nevertheless, the equipment investment cost of the heat pump distillation is relatively higher, and the extractive distillation separation process exhibits better economic feasibility. Through a comprehensive comparison of the separation effects under different scales, it is found that as the feeding flowrate of waste liquid increases, the utility cost proportion and economic benefit of the separation process show rising trends. Meanwhile, the heat pump distillation and azeotropic distillation are more suitable for long-term and large-scale production situations, and the extractive distillation is better suited for short-term and small-scale production ones.