Process design and intensification of multicomponent azeotropes special distillation separation via molecular simulation and system optimization

This work provides an overview of distillation processes,including process design for different distillation processes,selection of entrainers for special distillation processes,system integration and intensification of distillation processes,optimization of process parameters for distillation processes and recent research progress in dynamic control strategies.Firstly,the feasibility of using thermodynamic topological theories such as residual curve,phase equilibrium line and distillation boundary line to analyze different separation regions is discussed,and the rationality of distillation process design is discussed by using its feasibility.Secondly,the application of molecular simulation methods such as molecular dynamics simulation and quantum chemical calculation in the screening of entrainer is discussed for the extractive distillation process.The thermal coupling mechanism of different distillation processes is used to explore the process of different process intensifications.Next,a mixed integer nonlinear optimization strategy for the distillation process based on different algorithms is introduced.Finally,the improvement of dynamic control strategies for different distillation processes in recent years is summarized.This work focuses on the application of process intensification and system optimization in the design of distillation process,and analyzes the challenges,prospects,and development trends of distillation technology in the separation of multicomponent azeotropes.

Economy, environmental assessment and energy conservation for separation of isopropanol/diisopropyl ether/water multi-azeotropes via extractive distillation coupled pervaporation process

This wok proposed the extraction distillation coupled pervaporation(ED+PV) technology process using two different solvents to separate isopropanol(IPA) and diisopropyl ether(DIPE) from DIPE/IPA/H_(2)O ternary heterogeneous azeotropes in industrial wastewater from the synthesis of isopropanol in this study.Based on strict design specifications, simulation and sequential iteration methods are used for process design and optimization. Compared to the ethylene glycol(EG)-EG+H_(2)O process and the 1,3-propanediol(PDO)-IPA+H_(2)O process, the total annual cost(TAC) of the EG-IPA+H_(2)O process decreased by 20.76% and 7.86%(PDO). Compared to the EG-EG+H_(2)O process, the TAC of the PDO-IPA+H_(2)O process reduced 14%, but the global warming potential(GWP) and human toxicity of the PDO-IPA+H_(2)O process increased 11.3% and 4.07% respectively. Compared to the PDO-IPA+H_(2)O process, the EG-IPA+H_(2)O process saves 7.86%(TAC), 9.78%(GWP) and 9.85%(human toxicity). The ED+PV process with EG is superior to PDO in factors of TAC, energy consumption, human toxicity and environment. The EG-IPA+H_(2)O process changed the separation order of the products of the multi-azeotropic system, reduced the cost and energy conservation of the system, and enhanced the environmental protection evaluation of the process, is the best process through life cycle assessment for analyzing the economy, energy conservation, environmental assessment and human toxicity, designing cleaner products, controlling waste discharge, and promoting the chemical purification industry. This work provides a new process design and optimized separation ideas, will have a good guiding significance for the research and application separation of multi-azeotropic mixture with mixed solvents in organic wastewater from the cleaner chemical production, has been up to standard wastewater discharge process, and realized the development goal of carbon peak and carbon neutrality in the sustainable development of chemical clean industry.

A new combination process of distillation with salt extraction for separating organic solvent-water azeotropes

A novel process which can purify the organic solvents from their azeotropes with water is proposed. In this process,water can be drained off both from bottom and overhead of tower at the same time,and the organic solvent is concentrated in the tower and accumulated in the middle vessel at last. So the progress is time-shortened and energy-saving. The product purity is 99. 8% and the product yield is more than 99.5%. Simulation of liquid-liquid equilibrium (LLE) and the equipment operation data agree well with the experiment.

QSPR modeling of azeotropic temperatures and compositions for binary azeotropes containing lower alcohols using a genetic function approximation

Binary azeotropes, which contain two chemicals with a relative volatility of 1, are very common in the chemical industry. Understanding azeotropes is essential for effectively separating binary azeotropes containing lower alcohols. Experimental techniques and ab initio approaches can produce accurate results;however, these two processes are time consuming and labor intensive. Although thermodynamic equations such as UNIFAC are widely used, experimental values are required, and it is difficult to choose the best groups to represent a complex system. Because of their high efficiency and fast calculation speed, quantitative structure–property relationship(QSPR) tools were used in this work to predict the azeotropic temperatures and compositions of binary azeotropes containing lower alcohols. The QSPR models for 64 binary azeotropes based on centroid approximation and weighted-contribution-factor approximation were established using the genetic function approximation(GFA) procedure in Materials Studio software, and a leave-one-out cross-validation procedure was conducted.External tests of an additional 16 azeotropes were also investigated, and high determination coefficient values were obtained. The best QSPR models were explained in terms of the molecular structure of the azeotropes,and good predictive ability was obtained within acceptable prediction error levels.

Extractive Distillation of Methyl Acetate-Methanol Azeotrope Using [DMIM]DMP as Solvent

In order to separate methyl acetate and methanol azeotrope, the ionic liquid(IL) 1,3-dimethylimidazolium dimethylphosphate([DMIM]DMP) was used as the solvent. The Aspen Plus software was used to design and optimize the extractive distillation process. Under the optimized conditions, the mass fractions of methyl acetate and methanol were both above 99.5%. Compared with the dimethyl sulfoxide(DMSO) process, the [DMIM]DMP process has the advantages of saving energy and lower equipment investment cost. The result shows that using [DMIM]DMP as the solvent to separate a methyl acetate and methanol azeotrope has better prospect in industrial application.

Dynamic control analysis of interconnected pressure-swing distillation process with and without heat integration for separating azeotrope

Dynamic controls of pressure-swing distillation with an intermediate connection(PSDIC) process of ethyl acetate and ethanol separation were investigated.The double temperature/composition cascade control structure can perfectly implement effective control when ±20% feed disturbances were introduced.This control structure did not require the control of the flowrate of the side stream.The dynamic controllability of PSDIC with partial heat integration(PHIPSDIC) was also explored.The improved control structure can effectively control ±20% feed disturbances.However,in industrial production,simple controller,sensitive and easy to operate,is the optimal target.To avoid the use of component controllers or complex control structure,the original product purities could be maintained using the basic control structure for the PSDIC process if the product purities in steady state were properly increased,albeit by incurring a slight rise in the total annual cost(TAC).This alternative method without a composition controller combined with the energy-saving PSDIC process provides a simple and effective control scheme in industrial production.

Influence of Magnetic Field on the Rectification Process of Binary Heterogeneous Azeotrope

To improve separate effect of binary heterogeneous azeotrope in the magnetic field with different magnetic induction intensity, the influence of magnetic field on the rectification process of binary heterogeneous azeotrope was investigated with l-butanol-water system. The results show that the composition of liquid-liquid phase equilibrium of l-butanol-water system has definitely changed, the composition of l-butanol in light phase （l-butanol layer） increases by 1. 17%-1.63% and the composition of water in heavy phase （water layer） increases by 1.21%-1.58% under the influence of magnetic field. By separation of magnetization, the composition of l-butanol increases by 0.8%-1.2% and the recovery ratio of 1 -butanol increases by 1.6%-2.5%. Magnetic field has positive effect, however, the magnetized effect is not in proportion to magnetic induction intensity and has an optimum condition, in the range of 0.25 T-0. 3 T.

Investigation of energy-efficient heat pump assisted heterogeneous azeotropic distillation for separating of acetonitrile/ethyl acetate/n-hexane mixture

The conventional distillation is hard to accomplish the separation of acetonitrile/ethyl acetate/n-hexane mixture. Herein, a heterogeneous azeotropic distillation(HAD) without adding entrainer is proposed to separate ternary mixture. The proposed scheme is optimized via the simulated annealing algorithm and minimum total annual cost(TAC) is used as objective functions. To minimize energy consumption,heat pump is added on the basis of optimal heterogeneous azeotropic distillation and heat integration technology is used to further improve the energy recovery. The TAC, gas emission, energy consumption and exergy destruction are used to discuss the economy and environmental protection of processes.Among all the processes, the heat pump with higher preheating temperature(HPT) assisted HAD process by combining with heat integration(HAD-HPT-HI) has best performances on economic, environment,energy and exergy. Compared with conventional HAD process, the HAD-HPT-HI achieves the reductions of 52.17%, 68.86%, 65.87% and 65.46% on TAC, total energy consumption, gas emissions and exergy destruction, respectively.

Application of Homotopy-Newton Hybrid Method for Predicting Azeotropes

A homotopy-Newton hybrid method is proposed for predicting azeotropes, in which the set of homotopy equations with larger convergent domain is solved firstly to generate the better initial guess, then Newton algorithm is used to solve the azeotrope equations. It has been proved through some illustrative examples that the hybrid method has concurrently the advantages of the wide range of convergence, flexible demand for initial guess and good smoothness of iterative process as the homotopy algorithm, and the rapid convergent speed and high accuracy as Newton′s method. So the hybrid method is a prospective approach to predicting the azeotropes of nonideal mixtures.

基于反应精馏技术的乳酸乙酯工艺流程模拟与优化

提出了一种基于反应精馏技术制备乳酸乙酯的工艺流程.通过原料乙醇过量进料及乙醇脱水预处理的方法促进反应向右进行,提高乳酸乙酯产品的纯度;根据不同的乙醇-水共沸体系分离方法,建立了3种不同的乳酸乙酯工艺流程,即反应精馏-变压精馏(RD-PSD)流程、反应精馏-萃取精馏(RD-EX)流程和反应精馏-渗透汽化(RD-PV)流程;随后采用粒子群优化算法对各工艺流程进行多参数优化,以最小年总成本(TACmin)为优化目标,优化工艺流程参数,并对各流程进行经济和环境评价.结果表明:相较于RD-PSD流程和RD-EX流程,RD-PV流程有效降低了工艺投资,是一种极具潜力的节能低碳的乳酸乙酯工艺流程,较前两者其TAC分别降低了67.89%和29.33%,全局能量消耗(GEC)分别降低了70.17%和27.85%,CO_(2)排放量(ECO_(2))分别降低了68.36%和25.00%.

叠合式有机朗肯循环的热力学分析

针对有机朗肯循环(ORC)中传热过程对循环性能的影响,该文提出一种既相似但又区别于混合工质,各工质独立运行的叠合式有机朗肯循环(AORC)。AORC中,各工质进行串/并联的叠合换热,可形成类似于非共沸混合工质的温度滑移。由于各工质独立运行,使得叠合工质的温度滑移量可进行调节,以减小与外界热/冷源的传热温差,提高传热匹配性以及循环性能。以两种工质叠合的AORC为例进行循环性能分析,并与常规ORC进行对比。结果表明,AORC并不是各工质基本ORC的简单线性叠加,而是一种优化叠加。相比常规ORC,AORC的净输出功率最大可提升34.48%。但当热源温度高于高温工质的热源转折温度时,AORC趋近于高温工质的基本ORC。

R32/R134a自复叠热泵变组分浓度实验分析

为缓解热泵大温度跨度运行时容积制热量衰减严重的问题,提出一种新型变组分浓度调控自复叠热泵实验装置,采用非共沸混合制冷剂R32/R134a为工作介质,通过动态监测系统组分浓度分布、制热量、性能系数(COP)等关键性能参数,探究混合工质浓度变化对自复叠热泵循环性能的影响规律。结果表明:冷凝器出水温度或第一级节流阀开度增加,主路低沸点组分质量分数降低2.5%~8.1%。而随着充注量增加,主路低沸点组分质量分数逐渐增加,排气温度逐渐降低;当充注量增至2.8 kg,出水温度为65℃时,COP达2.22,压缩机排气温度仅为80℃。当低沸点组分质量分数从0.3增加至0.5,排气温度最高可降低25.4%。与单级蒸气压缩系统(SVC)相比,自复叠热泵系统排气温度降低31.2%,以上自复叠热泵组分浓度分布及性能变化规律表明该热泵系统在大温度跨度时具有较明显的性能优势,对于系统长期稳定运行以及节能效应具有显著作用。

双阳离子液体分离甲苯-正庚烷共沸体系——综合实验的设计与探索

构建了一种全新的专业设计型实验体系:双阳离子液体的制备及萃取分离甲苯-正庚烷共沸体系。合成并表征新型“绿色溶剂”双阳离子液体;以双阳离子液体作为萃取剂,测定其对甲苯-正庚烷共沸体系的分离能力并进行相图绘制。通过该综合实验教学,既促进学生对多学科基础知识的掌握,又能激发学生科研探索兴趣,培养其绿色化学意识与理念。

离子液体的制备及在甲醇-碳酸二甲酯共沸物分离中的应用现状

碳酸二乙酯(DEC)生产过程中,甲醇(MeOH)与碳酸二甲酯(DMC)形成二元共沸物,传统有机溶剂萃取精馏分离MeOH-DMC共沸物存在污染环境、萃取效率低及溶剂回收难等难题。离子液体作为一种新型溶剂,因其绿色环保、萃取效率高及可循环再利用等优势,在化工领域中展现出广泛的应用前景。简述了离子液体的种类及其性质,分析了离子液体典型的五种合成方法存在的优缺点,重点讨论了离子液体对MeOH-DMC共沸物的研究进展及其分离机理,指出了目前离子液体应用于MeOH-DMC共沸物分离中存在的问题,最后对离子液体的未来发展方向提出了展望。

隔壁塔萃取精馏及共沸精馏分离异丙醇-水体系的模拟与优化

分别采用隔壁塔萃取精馏(EDWC)与隔壁塔共沸精馏(ADWC)工艺制取无水异丙醇(IPA),借助Aspen Plus模拟软件建立二塔等价模型,利用灵敏度分析对主塔进料位置、夹带剂用量、侧线采出位置、侧线采出量及回流比等参数进行优化,结合塔的设计规范,以此确定最佳工艺参数。模拟结果显示,与常规双塔工艺流程相比,在完成相同的分离要求下,EDWC工艺的冷凝器和再沸器热负荷分别降低32.38%,12.39%,设备费用和总年度费用分别节约29.34%,4.87%;ADWC工艺的冷凝器和再沸器热负荷分别降低29.57%,23.41%,设备费用和总年度费用分别节约16.87%,22.41%。ADWC用于制取无水IPA在节能降耗及节约设备成本方面表现出明显的优势。

绿色节能的萃取精馏工艺设计与强化

萃取精馏是一种通过添加新的溶剂来分离多组分共沸物的分离技术,能够有效地提取和分离混合物中的目标物质。在传统的萃取精馏工艺存在着分离效率低、能耗高和环境污染严重等不足,急需设计节能高效的强化萃取精馏工艺的背景下,首先总结了萃取精馏工艺的设计路线,指出热力学拓扑理论在萃取精馏工艺设计中的重要地位,研究了过程强化在精馏工艺设计中的应用。介绍了萃取精馏中萃取剂的选择方法,详细说明了相对挥发度和分子模拟在其中的应用,介绍了萃取精馏工艺参数优化和设计的方法,讨论了顺序迭代优化和多目标优化的优势和劣势,可为绿色节能萃取精馏工艺的设计与强化提供新的思路和方法,为相关领域的研究和应用提供参考。

正戊烷共沸精馏甲缩醛-甲醇分离过程模拟与优化

选择正戊烷为共沸剂,研究甲缩醛-甲醇体系的共沸精馏分离工艺。以三元相图为基础进行概念设计,确定了合适的共沸精馏分离流程。采用Aspen Plus模拟软件对该过程进行工艺模拟与优化,分析确定了优化的操作压力、操作温度和溶剂比等工艺操作条件,对比考察了精馏塔塔板数、进料位置、溶剂比等工艺参数对产品质量和能耗指标的影响。结果表明,采用正戊烷作为共沸剂的共沸精馏工艺,可高效地实现甲缩醛-甲醇混合物的分离,甲缩醛产品质量浓度可达99%,甲缩醛回收率不低于99.9%。与常规变压精馏工艺相比,共沸精馏工艺的能耗约可降低36%,具有较好的工业应用价值。

乙酸+异丙醇酯化体系中汽液平衡测定及萃取精馏

汽液平衡数据对于共沸物分离具有十分重要的地位,为了解决乙酸+异丙醇酯化反应体系中的共沸物分离的问题,采用Dvorak-Boublik平衡釜测定了乙酸+异丙醇+乙酸异丙酯、乙酸+异丙醇+水、乙酸+乙酸异丙酯+水、异丙醇+乙酸异丙酯+水4个三元体系的汽液平衡数据,对实验数据进行热力学一致性检验和NRTL(nonrandomtwo-liquid)模型关联。通过残留曲线图分析了共沸体系分离的可行性,利用Aspen Plus对异丙醇+乙酸异丙酯+水体系进行萃取精馏工艺模拟和优化。结果表明,分离得到乙酸异丙酯质量分数≥98%,异丙醇质量分数≥99%,研究结果不仅补充了部分乙酸+异丙醇酯化反应体系的三元汽液平衡数据,也为体系的共沸物分离提供理论依据。

化学法分离甲醇-碳酸二甲酯共沸物的研究

针对甲醇-碳酸二甲酯二元共沸物分离工艺复杂、反应能耗高以及环境污染严重等问题,采用马来酸酐与甲醇发生酯化反应的化学法分离共沸物,同时制备高附加值产品马来酸二甲酯。系统考察了催化剂、催化剂质量分数、带水剂、带水剂质量分数、反应时间以及醇酐物质的量的比对共沸物分离效果以及酯化收率的影响。结果表明:加入1.0%的离子型树脂催化剂、15%的环己烷带水剂、醇酐物质的量的比为3.0、反应9 h时,马来酸酐转化率为97.10%,马来酸二甲酯收率为96.80%,碳酸二甲酯收率为97.00%。

热泵技术在二氯甲烷和甲醇分离中的应用研究

针对传统变压精馏技术(PSD)在分离二氯甲烷(DCM)-甲醇(MeOH)混合物时的高能耗问题,提出了一种基于热泵辅助的变压精馏(PPSD)优化工艺,并深入探讨了热泵配置的技术可行性和经济效益。通过组合曲线和经济性分析,对比了热泵方案的节能和经济效果。结果显示,与传统PSD工艺相比,热泵辅助的PPSD工艺能够降低29.96%的能耗,减少40.45%的年度总成本(TAC),同时能降低44.23%的CO_(2)排放量,充分展现了热泵辅助变压精馏工艺的优越性。