四氢呋喃-乙醇变压精馏分离

共沸混合物分离是化工过程中常见的分离难题。变压精馏是根据物系压力改变而使液体混合物共沸点组成发生变化,进而使共沸物系得以分离的一种有效分离方法。在热力学分析基础上,提出了四氢呋喃-乙醇液体混合物变压精馏分离双塔工艺流程。以NRTL-RK为物性计算方法,利用Aspen Plus模拟软件对变压精馏分离工艺过程进行分析及模拟,并对工艺参数进行优化。研究结果表明:在常压塔和0.8 MPa高压塔组成的双塔流程中变压精馏可将四氢呋喃-乙醇最低共沸混合物进行较好的分离。     

原甲酸三甲酯-醋酸萃取精馏全局多目标优化

在生产杀菌剂嘧菌酯中间体过程中,反应物原甲酸三甲酯（TMOF）与生成物醋酸（HAc）发生共沸,导致反应物堆积和原料损耗。为解决共沸物分离问题,使用Hayden-O'Connell修正的UNIFAC基团贡献法研究其汽液平衡,设计常规萃取精馏（CED）、侧线萃取精馏（SED）、隔壁塔萃取精馏（EDWC）三种工艺,以分离组分摩尔纯度、再沸器热负荷（Q）、年度总费用（TAC）为目标,运用灵敏度耦合箱线图响应面法（S-BBD）对三种工艺参数分别优化。结果表明,优化方法预测值与实际值存在较优拟合关系, CED、SED、EDWC对TAC和Q的预测误差均不超过1%。分离纯度相同时,SED较CED节约10.37%TAC和6.88%热负荷,EDWC较CED节约10.65%TAC和10.53%热负荷,三种工艺方案均可为化工实际生产提供理论基础。     

Fuel grade ethanol by diffusion distillation: an experimental study

BACKGROUND: Fuel grade ethanol (anhydrous ethanol) is considered to be an excellent alternative clean burning fuel to gasoline. It is now used as an additive to gasoline to enhance its octane number and combustibility. Owing to its high energy values, ethanol is the most promising future biofuel. Because of azeotrope formation, anhydrous ethanol cannot be achieved by conventional distillation. Diffusion distillation is one of the several processes that can be used to separate azeotropes. Diffusion distillation takes advantage of differences in relative rates of diffusion using inert gas as selective filter. RESULTS: Effect of vaporization temperature and feed composition on diffusion distillation of an ethanol–water mixture using air as the inert gas has been studied. A new quantity S_az(N₂/N₁) has been suggested to find the optimum vaporization temperature. In the present study this was found to be about 46 °C. The pseudo‐azeotrope has been observed at 0.697 mole fraction of ethanol at a vaporization temperature of 50 °C. Separation is effected by diffusion distillation even at the azeotropic ethanol mole fraction of 0.894. The experimental results were compared with a Stefan–Maxwell equations based mathematical model and found to be in good agreement with theoretical results. CONCLUSIONS: Experimental results demonstrate that fuel grade ethanol can be produced by diffusion distillation. The new quantity S_az(N₂/N₁) is a key variable for vaporization temperature optimization. Copyright © 2011 Society of Chemical Industry     

1,4-丁二醇分离乙酸甲酯-甲醇二元恒沸物的研究

利用1,4-丁二醇与乙酸甲酯-甲醇二元恒沸物形成三元恒沸物,研究了乙酸甲酯与甲醇恒沸物的分离工艺。实验采用精馏、常压蒸馏、减压蒸馏及冷冻的方法,主要研究了各种方法对甲醇分离的影响,并获得了较佳的工艺条件。研究得出常压蒸馏法可行,乙酸甲酯纯度达到99.7%,收率98.1%,甲醇纯度96.1%,收率95.2%。     

乙二醇独乙醚-甲基异丁基酮-水三元非均相共沸物系分离研究

实验考察了液液萃取法、加盐分相法、共沸精馏法对乙二醇独乙醚-甲基异丁基酮-水( EC+ MIBK+ H2O)三元非均相共沸物系的分离效果.结果表明:以苯、甲苯、环己烷为萃取剂的液液萃取法分离效果较差;以K2CO3晶体为加盐相的加盐分相法,虽然可以取得较好的分离效果,但是不利于工业化生产;以甲基异丁基酮为夹带剂的间歇式共...     

Synthesis and characterization of moisture‐cured polyurethane membranes and their applications in pervaporation separation of ethyl acetate/water azeotrope at 30°C

NCO‐terminated polyurethane membranes were prepared using diisocyanate, diol, and trimethylolpropane (TMP) using an NCO/OH ratio of 1.6 : 1. Prepolymer was chain‐extended using cellulose acetate butyrate (CAB) in the ratios of 2 : 1, 4 : 1, and 3 : 1 of NCO/OH. Polyurethane (PU) membranes were characterized by differential scanning calorimeter (DSC) and thermogravimetry (TGA) to investigate their thermal properties. Equilibrium sorption studies were carried out at 30°C in water and ethyl acetate media as well as in their binary mixtures. The influence of CAB on pervaporation (PV) separation of an ethyl acetate/water (92/8, w/w, i.e., azeotropic composition) mixture was investigated. Membranes in this study showed a selectivity of 42.42 with a flux value of 0.187 kg/m/h for 3 : 1% NCO/OH containing PU membrane. In order to gain a more detailed picture of the molecular transport phenomenon, we performed the sorption gravimetric experiments at 30°, 35°, 40°, and 50°C to compute diffusion, swelling, sorption, and permeability coefficients of PU membranes in the azeotropic mixture of ethyl acetate and water. Activation parameters for diffusion and permeation were computed from the Arrhenius equation to understand the polymer/solvent interactions. Sorption trends and diffusion anomalies were established through an empirical equation after estimating the diffusion parameters. © 2006 Wiley Periodicals, Inc. J Appl Polym Sci 103: 3405–3414, 2007     

环氧乙烷环氧丙烷无规聚醚短碳链起始端基结构控制

引发体系中的微量水分是影响环氧乙烷环氧丙烷无规聚醚起始端基结构 ,并进一步影响其分子量和使用性能的重要因素。研究了反应精馏方式、温度、物料配比等工艺条件对丁醇无规聚醚引发体系含湿量的影响 ,结果表明 :以甲苯或二甲苯为脱水剂的三元共沸反应精馏工艺在温度高于 1 1 5℃时的脱水效果较好 ,并用二元共沸反应精馏方法的对工艺进行了改进 ,在 m (丁醇 )∶ m (氢氧化钾 ) =1 1∶ 1时 ,效果较好 ,提出了适用于以低沸点醇类物质为起始剂的环氧乙烷环氧丙烷无规聚醚的起始端基结构控制方法。     

填料毛细管精馏过程中气液两相流动特性及其影响因素的数值分析

通过构建数值模型,对填料毛细管精馏塔内气液两相的流场和速度场分布进行了计算分析,研究了在不同的填料孔隙率、气相和液相进口速率等系统结构和操作工艺条件下,填料毛细管精馏塔内气液两相的速度场分布特性。通过对气液两相分布状态的分析,明确了符合最优气液两相相际传质特性的结构和工艺参数,对后续填料毛细管精馏的实验具有良好的指导意义。     

加盐萃取精馏分离醋酸甲酯-甲醇二元恒沸物

用改进的O thm er汽液平衡釜测定了0.101 3M Pa下醋酸甲酯-甲醇体系在萃取剂和盐存在下的相对挥发度,测定了全浓度范围的汽液平衡数据,并进行了加盐萃取精馏工艺的实验。结果表明,水作为萃取剂,加入醋酸钾,可提高醋酸甲酯-甲醇体系的相对挥发度,加盐萃取精馏比普通的萃取精馏有优势,当溶剂体积比为1∶1时,萃取精馏塔塔顶采出的醋酸甲酯的质量分数可达到99%以上,萃取剂回收率达98%,盐可以全部回收。