低共熔溶剂萃取精馏分离乙醇-水共沸物的研究

分别以氯化胆碱/甘油(摩尔比为1∶2)低共熔溶剂(Reline)和乙二醇为萃取剂,对乙醇脱水萃取精馏过程进行模拟研究,并以最小年度总费用TAC为目标函数,对2种工艺流程进行优化,得到了最优的操作条件。结果表明,与乙二醇萃取精馏流程相比,Reline萃取精馏中萃取剂用量降低20%,能耗费用降低21. 68%,年度总费用TAC降低19. 66%,具有明显的节能优势。对Reline常规萃取精馏进行节能研究,发现对该流程进行换热网络优化后,可使年总费用TAC下降7. 95%;而隔壁塔并不能降低整个过程的年总费用。     

乳酸过量进料反应精馏合成乳酸甲酯研究

针对乳酸与甲醇酯化反应体系中乳酸和甲醇的沸点分别为最高沸点与最低沸点,属于反应精馏设计中最劣沸点序列,导致乳酸甲酯反应精馏过程反应段效率低下的问题,设计了乳酸过量进料的反应精馏合成乳酸甲酯工艺。以年度总费用(TAC)为目标,采用序贯优化法对过程工艺参数进行优化设计,结果表明当乳酸过量比为1.3、反应精馏塔反应塔板数为7块、提馏段塔板数为16块(包括塔底再沸器)时,过程年度总费用达到最小为3.05×10~6 CNY×a~(-1)。相比于等比进料合成乳酸甲酯反应精馏工艺,乳酸过量进料反应精馏工艺能耗降低70.4%,TAC减小51.2%,更具经济效益。     

三种萃取精馏法生产1,3-丁二烯的经济评价

利用化工流程模拟软件Aspen Plus对国内常用的ACN法、DMF法、NMP法三种1,3-丁二烯萃取精馏工艺进行了全流程模拟优化和热集成分析。模拟结果表明,三种工艺的1,3-丁二烯产品质量均满足设计要求,且相关参数与实际生产操作数据吻合较好。在此基础上,以年度总费用(TAC)最小为目标函数,利用最新经济数据评价了三种工艺的经济技术水平。结果表明,三种工艺的年度总费用以NMP法最低,DMF法最高,NMP法具有明显的经济优势。     

减压逆流多效精馏回收膜工业废水中的DMAC

针对膜工业中所产生的质量分数为5%～15%的N,N-二甲基乙酰胺(DMAC)废水,提出了分离DMAC废水减压逆流的双效、三效和四效精馏工艺流程。通过实验和Aspen流程模拟对多效精馏的工艺进行了研究。利用响应面法(RSM)对多效流程进行了优化,以最小年度总费用(TAC)为目标函数,确定了回收废水中DMAC最佳方案为减压逆流三效精馏工艺。     

分割式热泵精馏流程的优化设计及运行调优

从系统能量平衡的角度,提出了适合于分割式热泵精馏优化设计和运行调优的系统参数———压缩机进气量,建立了以年总费用最小为目标函数的优化设计数学模型和以年操作费用最小为目标函数的优化运行数学模型。以酒精精馏为例,利用Aspenplus模拟软件对此流程进行了优化计算。与常规精馏相比,此流程节能效果和经济效益非常显著。文中还分析了优化结果的运行调优问题。     

反应精馏隔壁塔提纯乳酸工艺研究

以反应精馏隔壁塔替换传统的反应精馏塔,形成了新型双向反应精馏隔壁塔提纯乳酸工艺,并通过灵敏度分析和遗传算法对工艺流程进行了优化,优化后的反应精馏隔壁塔工艺与传统反应精馏工艺相比年度总费用减少10.15%,CO₂排放速率降低31.75%,乳酸收率提升4.68%。     

萃取精馏分离苯/环己烷共沸体系模拟与优化

以糠醛作为萃取剂分别使用常规萃取精馏、隔壁塔萃取精馏和差压热集成萃取精馏对苯和环己烷体系进行分离研究,使用流程模拟软件Aspen Plus V8.4进行模拟分析,对初步设计的三稳态流程,分别进行灵敏度分析,使用多目标遗传算法对过程进行整体优化以获得最优结构参数。结果表明,隔壁塔萃取精馏和差压热集成萃取精馏相对于常规萃取精馏所需再沸器热负荷可分别减小21.5%和15.7%。对三工艺流程进行经济性分析,发现与常规流程相比,隔壁塔萃取精馏的年总费用下降了6.0%,而差压热集成萃取精馏年总费用增加了50.8%,为萃取精馏分离苯/环己烷共沸体系工业化设计提供了理论依据和设计参考。     

萃取精馏分离异丙醚-异丙醇-正丙醇三元物系模拟与优化

利用Aspen模拟软件,采用NRTL-RK模型,通过对体系气液相平衡特性分析,确定了以二甲基乙酰胺为萃取剂萃取精馏分离异丙醚-异丙醇-正丙醇三元体系,提出了三塔精馏和四塔精馏2种分离方案,以总热负荷最小为目标函数,优化了各精馏塔工艺参数,并比较了2种方案的年度总费用,结果表明四塔流程具有明显的经济优势。     

变压-塔顶蒸汽再压缩精馏分离甲苯-正丁醇体系优化工艺

针对变压精馏分离甲苯-正丁醇的高能耗问题,采用塔顶蒸汽再压缩热泵技术对变压精馏进行改造。利用Aspen Plus流程模拟软件,以年度总费用(TAC)最小为目标函数,利用序贯迭代法确定变压精馏、变压-塔顶蒸汽压缩式热泵精馏的最优工艺参数。从节能和经济的角度对工艺进行评价,结果表明:变压-塔顶蒸汽压缩式热泵精馏更具有优势。     

热集成变压精馏分离乙二胺-水共沸体系的模拟优化

针对乙二胺-水共沸物组成对压力较为敏感的特性,采用部分热集成变压精馏工艺分离该共沸物。先利用Aspen Plus软件对该工艺进行稳态模拟,再以理论塔板数、进料位置、回流比为优化变量,水和乙二胺的纯度为约束,以年度总费用（total annual cost,TAC）为目标函数建立乙二胺-水共沸体系分离系统的优化设计模型。采用列队竞争算法对该分离过程主要工艺参数进行优化,得到了变压精馏分离乙二胺-水体系的最佳工艺操作参数及设备参数。模拟结果表明,利用算法对多变量进行同时优化可得到更具经济效益的分离系统,与传统优化结果相比,可降低TAC约7.31%。在此基础上,对高压塔的操作压力进行优化分析,将其由2atm提升至4atm（1atm=101325Pa）,并对流程其他参数进行优化,可显著降低TAC约24.62%。进一步,采用部分热集成比普通变压双塔精馏降低TAC约21.87%     

基于分割式热泵的2-甲氧基乙醇-水精馏工艺模拟

基于2-甲氧基乙醇-水体系的共沸特性,应用分割式热泵精馏用于该体系的分离。采用UNIQUAC方程计算该体系的相平衡数据,并利用实验数据对UNIQUAC方程中的二元交互作用参数进行修正。利用Aspen Plus过程模拟软件中的Radfrac精馏模型和Compr等熵压缩模型,以年总费用最小为目标函数,对提出的分割式热泵精馏工艺进行了模拟与优化,得到了合适的工艺参数,如分割点摩尔分数为x(H2O)=0.17、压缩机进气量为6.16 t/h等关键工艺变量。模拟结果表明,与常规热泵精馏工艺相比,分割式热泵精馏工艺的年总费用可节约34.4%,操作费用可节约36.3%。     

Design and control of reactive distillation for hydrolysis of methyl lactate

Esterification of raw lactic acid from fermentation broth and then hydrolysis of lactate ester in reactive distillation column is an effective process for purification of lactic acid. Reactive distillation for hydrolysis of methyl lactate is studied. First, the thermodynamic properties and reaction kinetics are analyzed; then the reactive distillation column is designed based on the objective function total annual cost. The effects of tray number of rectifying section, tray number of reactive section, and feed location on the total annual cost are investigated. And a dual-temperature control structure is proposed for the optimal reactive distillation column, and the results show that it works quite well for this hydrolysis system.     

变压精馏分离甲苯-乙醇体系的经济最优化设计

甲苯-乙醇体系的共沸组成与相对挥发度对压力比较敏感,可用变压精馏分离该体系。利用Aspen化工流程模拟软件,以年度总费用最小为目标函数,以NRTL为热力学计算模型,采用序贯迭代法确定普通、部分热集成和完全热集成的变压精馏最优工艺参数。结果表明完全热集成更具有优势。     

The effects of feed splitting and heat integration in classical arrangements on cost minimization in separation of ternary mixture

Multi-component separation by distillation is known as a conventional method in chemical processes. In this study the effects of feed splitting on three classical arrangements (with and without heat integration) were investigated in order to reduce the total annual cost (TAC). Ternery mixture separation (propane, butane and pentane) by distillation was selected as a case study. An optimization problem was defined based on the effective parameters affecting the total annual cost. Optimum values for decision variables were calculated by applying the genetic algorithm. Calculation results showed that the heat integration procedure in the feed splitting method reduced the TAC significantly. It was also indicated that the prefractionator arrangement with heat integration resulted in the greatest decrease in the total annual cost.     

Design Optimization of a Crude Oil Distillation Process

In this work, the optimal design of a crude oil distillation unit was made. Since the method used here is based on the general optimization framework, it is possible to design the process systematically. The results of this study gave better performances than that of the existing process. The process in this study is currently in operation and has the capacity of 150,000 BPSD. Feed locations, heat duties of pumparounds and operating conditions of the preheat train are selected as variables, and the energy consumption, operating cost and annual cost are formulated as objective functions. The optimal feed locations of both the main column and stabilizer are obtained by solving rigorous models and mixed integer nonlinear programming. Considering the results of the optimal feed tray, the cost optimization is carried over to obtain the optimal annual cost, which considers both the capital and operating cost, which is decreased from US$10,649,000/year to USdollar;9,185,230/year.     

基于双塔精馏的甲醇-碳酸二甲酯分离工艺

基于甲醇和碳酸二甲酯体系的共沸特性,应用双效热集成和分割式热泵两种双塔精馏工艺进行该体系的分离研究。利用文献报道的实验数据对选用的Wilson物性方程中的二元交互作用参数进行回归修正。利用Aspen Plus模拟软件,以年运行总费用最小为目标函数,分别对提出的两种双塔精馏工艺进行模拟与优化,得到合适的工艺参数。模拟结果表明,两种双塔精馏工艺均比单塔加压精馏工艺其能耗更低、年运行总费用更少。就两种双塔精馏工艺而言,分割式热泵精馏工艺较双效热集成精馏工艺,可节约设备投资费用约2.69%,年运行总费用节约17.33%。     

Smooth penalty function method for rigorous optimization of distillation processes

Integer decisions on stage numbers and feed locations, and global optimality are still challenging for rigorous optimization of distillation processes. In the present article, we propose a smooth penalty function method to address both these problems. The proposed method is based on the relaxation of the integer decision problem into continuous nonlinear programming (NLP) problem by adopting the bypass efficiency model developed by Dowling and Biegler. A smooth penalty term (SPT) is proposed and added to the total annual cost (TAC) function to form a new objective function, namely, the smooth penalty function. Using the new objective function, the problem is initially solved with negative weight coefficients for the SPTs regarding each column section to get an optimum near the global optimum of the SPT. Then, starting from this solution, the problem is solved again iteratively by increasing the values of the weight coefficients until all the stage numbers become integers. The performance of the method is validated by an illustrating problem and in three case studies, including a reactive distillation optimization problem.     

Conceptual design of an extractive distillation process for the separation of azeotropic mixture of n-butanol-isobutanol-water

In many chemical processes, large amounts of wastewater containing butanol and isobutanol are produced. Given that n-butanol-isobutanol-water can form triple azeotrope, high-purity butanol cannot be recovered from the wastewater by ordinary distillation. To economically and effectively recover butanol from this kind of wastewater, 1,4-butanediol is selected as an extractant to break the formation of the azeotropes, and a doubleeffect extractive distillation process is proposed. The conceptual design of the proposed process is accomplished based on process simulation. With the proposed process, the purity of recovered butanol and water is greater than 99.99 wt%. In comparison with the conventional azeotropic distillation process, economic analysis shows that the operating cost of the proposed process is lower:when the capacity of wastewater treatment is 100 t·h^-1, the total operating cost decreases by 5.385×10⁶ USD per year, and the total annual cost of the new process decreases by 5.249×10⁶ USD per year. In addition, in the extractive distillation system, variable effects on separation purities and cost are more complex than those in the ordinary distillation system. The method and steps to optimize the key variables of the extractive distillation system are also discussed in this paper and can provide reference for similar studies.     

Application of a simulated annealing algorithm to design and optimize a pressure-swing distillation process

The design and optimization of pressure-swing distillation (PSD) have a critical impact on its economics. An optimization method based on simulated annealing algorithm (SAA) was proposed. The move generator and cooling schedule of the SAA were discussed, and suitable parameter settings were investigated. Two cases of PSD with and without heat integration were optimized by the SAA-based optimization method using procedures of pressure specified and pressure optimized. The results of the process without heat integration were compared with conventional optimization methods. For the acetone-methanol system, the total annual cost (TAC) shows a 5.69% decrease with the pressure specified and a 17.32% decrease with the pressure optimized. For the methanol-chloroform system, the TAC shows a 1.79% decrease with the pressure specified and a 9.04% decrease with the pressure optimized. The SAA-based optimization method has the advantages of a high probability to obtain the global optimum, automatic calculation, and less computing time.