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    低含水量乙酸废液分离过程的模拟与能耗-经济性分析

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

    • 摘要: 乙酸生产过程中会产生大量废液,对其进行回收是乙酸企业实现节能减排和可持续发展的重要手段之一。针对低含水量的乙酸废液分离和回收问题,本文分别构建了常规精馏、萃取精馏、共沸精馏和热泵精馏共4种不同分离工艺的模拟流程,分析对比了这4种分离工艺的能耗和经济性,并以一个实例研究4种方法的优缺点。结果表明,4种分离工艺均能满足GB/T 1628—2020要求。在能耗和公用工程成本上,采用热泵精馏的分离流程能耗最低、但设备投资费用较高,而采用萃取精馏的分离流程能耗最高但分离工艺经济性更好。综合对比不同乙酸废液回收规模下的分离效果,发现随着废液处理量增加,公用工程成本与经济效益都会增加,热泵精馏和共沸精馏更适合长期、大规模生产,而萃取精馏适合短期、小规模生产。

       

      Abstract: 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.

       

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