欢迎访问过程工程学报, 今天是

过程工程学报 ›› 2018, Vol. 18 ›› Issue (5): 1003-1012.DOI: 10.12034/j.issn.1009-606X.217378

• 过程与工艺 • 上一篇    下一篇

甲醇-苯共沸体系变压精馏分离工艺的动态控制

吕利平1,3, 李 航3, 李 兵1,2*, 徐建华1   

  1. 1. 长江师范学院化学化工学院,三峡库区环境监测与灾害防治工程研究中心,武陵山片区绿色发展协同创新中心,重庆 涪陵 408100 2. 中化重庆涪陵化工有限公司,重庆 涪陵 408100 3. 西南石油大学化学化工学院,四川 成都 610500
  • 收稿日期:2017-10-24 修回日期:2018-02-01 出版日期:2018-10-22 发布日期:2018-10-12
  • 通讯作者: 李兵
  • 基金资助:
    重庆市教委项目;重庆市“科技创新领军人才支持计划”;重庆市社会事业与民生保障科技创新专项项目;重庆市涪陵区科委项目

Dynamic control of pressure-swing distillation for separating azeotropic system of methanol/benzene

Liping LÜ1,3, Hang LI3, Bing LI1,2*, Jianhua XU1   

  1. 1. School of Chemistry and Chemical Engineering, Research Center for Environmental Monitoring, Hazard Prevention of Three Gorges Reservoir, Collaborative Innovation Center for Green Development in Wuling Moutain Area, Yangtze Normal University, Fuling, Chongqing 408100, China 
    2. Sinochem Fuling Chongqing Chemical Industry Co., Ltd., Fuling, Chongqing 408100, China 3. School of Chemistry and Chemical Engineering, Southwest Petroleum University, Chengdu, Sichuan 610500, China
  • Received:2017-10-24 Revised:2018-02-01 Online:2018-10-22 Published:2018-10-12
  • Contact: Bing --LI

摘要: 基于甲醇和苯共沸体系的压敏性,利用Aspen Plus和Aspen Dynamics软件对变压精馏分离该体系的稳态工艺进行了模拟和优化,研究了该工艺的动态特性,提出了控制产品纯度的3种控制结构:基础控制结构、比例控制结构和双比例与温度?组分联合控制结构,通过对控制结构添加±20%的组分和流量干扰测试控制结构的稳定性. 结果表明,基础控制结构基本能实现稳健控制,但不能解决组分干扰引起的产品纯度偏差过大等问题;比例控制结构可实现相对稳健的控制,但改进效果不显著;双比例与温度?组分联合控制结构在受到20%进料和组分干扰后,产品纯度能较快恢复至设定值的99.90%,实现稳健控制.

关键词: 甲醇, 苯, 变压精馏, 动态控制

Abstract: The design and control of the pressure swing distillation (PSD) for the separation of methanol and benzene binary minimum azeotropic system were explored based on the pressure sensitivity of the azeotropic composition. Aspen Plus (8.4 V) software was used to simulate and optimize the steady state process by the minimization of total annual cost (TAC). Based on the optimal steady state results, three kinds of the control structure including basic control structure, ratio control structure and double ratio and temperature?component combined control structure for the PSD process were put forward to maintain the purity of the product. According to the temperature slope criterion by Luyben, the stage 13th in the low pressure distillation is selected as the temperature sensitive stage. However, it was somewhat difficulty for selecting the temperature sensitive stage for the high pressure distillation. Because the maximum value of the temperature slope was the stage 21th which was the bottom of this column. If the stage 21th was chosen to the temperature sensitive stage, it was very difficult to maintain the temperature as a constant value. So the stage 20th was selected as the suitable temperature sensitive stage by the liquid composition distribution. The ±20% feed flowrate and composition disturbances were used to test the dynamic performances of these control structures. The results showed that the selection of the temperature sensitive stage was reasonable and the basic control structure can basically achieve robust control, but the problem of product purity deviation due to component disturbances cannot be solved. Ratio control structure can achieve relatively robust control, but the purity of methanol in the bottom stream of the LPC (B1) still cannot return back to the desired value. The double ratio and temperature?component combined control structure can effectively maintain the product purity of 99.90% when the control loop arrives at a new steady state after encountering ±20% changes in feed flowrate and feed methanol.

Key words: methanol, benzene, pressure-swing distillation, dynamic control