摘要
基于变压精馏分离乙酸乙酯/正己烷共沸体系两塔的温差,利用Aspen Plus软件,以年度总成本最小为目标函数,对部分及完全热集成变压精馏工艺进行了稳态模拟及优化。在此基础上,利用Aspen Dynamics软件开发了多种控制结构,通过引入不同进料流量及组成的扰动测试控制结构的有效性。结果表明,完全热集成变压精馏工艺比部分热集成变压精馏工艺的经济性稍好。动态响应结果表明,部分热集成变压精馏工艺的压力-补偿温度控制结构可有效处理不同程度的干扰,能有效提高控制结构对干扰的响应速度,缩短达到新稳态的时间,保证乙酸乙酯和正己烷产品纯度在99.9wt%之上;而完全热集成变压精馏工艺的组分-温度串级控制结构仅能处理较小的组分和流量干扰,实现稳健控制,无法处理较大的干扰。综合比较两种工艺的经济性和可控性,认为部分热集成变压精馏工艺分离乙酸乙酯/正己烷共沸体系优于完全热集成变压精馏工艺。
The azeotropic composition of ethylacetate/n-hexane azeotropic system dramatically shifts with pressure. Therefore, this system can be effectively separated by pressure-swing distillation(PSD). In order to save the total annual cost(TAC) and energy, the partially and fully heat-integrated pressure-swing distillation(HIPSD) between condenser and reboiler of two columns were used in this process. The simulation and optimization of different heat-integrated PSD processes were carried out by using Aspen Plus software. The results showed that the energy cost, equipment cost and TAC of the fully HIPSD process had further reductions of 12.24%, 4.38% and 8.60% compared with partially HIPSD process. On the basis of the best optimal process, feed flowrate and composition disturbances with several different degrees were introduced to test the dynamic characteristics of different control structures for partial and fully HIPSD processes by Aspen Dynamics. For partially HIPSD process, three kinds of control structure including basic control structure, proportional control structure and pressure-compensated temperature control structure were developed to test the effectiveness of control structures. The results of the dynamic response showed that the pressure-compensated temperature control structure could handle the feed flowrate and composition disturbances with different degrees and effectively maintain the purity of ethyl acetate and n-hexane products at 99.9 wt%. For fully HIPSD process, the composition/temperature cascade control structure could effectively handle the small disturbances(±5% and ±10%) and achieve robust control, but this control structure cannot effectively maintain the product purity of 99.90 wt% and realize robust control when subject to ±20% feed and composition disturbances. Compared with the partially HIPSD mode, the fully HIPSD mode could handle much smaller feed flow rate and composition disturbances despite of a little economic benefit. Therefore, the selection of energy-saving modes for the separation process should weigh economy against controllability.
作者
吕利平
李航
何树华
徐建华
李兵
Liping LÜ;Hang LI;Shuhua HE;Jianhua XU;Bing LI(School of Chemistry and Chemical Engineering,Yangtze Normal University,Chongqing 408100,China;School of Chemistry and Chemical Engineering,Southwest Petroleum University,Chengdu,Sichuan 610500,China;Sinochem Fuling Chongqing Chemical Industry Co.,Ltd.,Chongqing 408100,China)
出处
《过程工程学报》
CAS
CSCD
北大核心
2019年第6期1167-1177,共11页
The Chinese Journal of Process Engineering
基金
重庆市科技创新领军人才支持计划资助项目(编号：CSTCCXLJRC201703)
重庆市社会事业与民生保障科技创新专项基金资助项目(编号：cstc2017shms A90016)
关键词
乙酸乙酯
正己烷
热集成
变压精馏
控制
ethyl acetate
n-hexane
heat integration
pressure-swing distillation
control
