基于样条插值模型的间歇精馏模拟与预测控制

以Aspen Batch Distillation（ABD）中的间歇精馏仿真系统为过程原型,提出了利用过程的模拟测试数据来建立间歇精馏过程的样条插值简化模型（spline interpolation model, SIM）。结合变回流比下的动态修正函数,构造出了一种简单实用的动态模型。该模型可有效模拟不同组分浓度下回流比发生变化时馏出液浓度和流量的动态变化情况。以该模型作为预测模型,进一步提出了一种变回流比的预测控制（model predictive control, MPC）算法来使馏出液浓度按照期望的设定值变化。控制仿真结果表明该控制方案计算简单,同时具有较好的控制效果。     

Application of short path distillation for recovery of polyphenols from deodorizer distillate

During physical refining of oil derived from ‘high temperature short time’ (HTST) pretreated rapeseeds, polyphenols are separated from the oil during deodorization and accumulate together with other high‐value minor compounds in the so‐called deodorizer distillate. For recovery of these compounds single‐stage and multistage short path distillations were carried out in a laboratory scale apparatus at evaporation temperatures between 110 and 170°C and pressures between 0.006 and 0.01 mbar. In addition, the removal of traces of pesticides from rapeseed deodorizer distillate was investigated. It was observed that these compounds can be separated from deodorizer distillate by means of short path distillation very effectively. On the basis of these experiments, a recovery process for polyphenols was proposed involving short path distillation, acid catalyzed esterification with methanol, solvent crystallization and solvent extraction processes. The final product was a polyphenol enriched extract containing about 14% of polyphenols. A polyphenol recovery of 50% is considered to be reachable and fractions rich in tocopherols and sterols may be obtained as by‐products.     

实验室精馏装置用于乙醇-水分离的工艺探索与优化

实验室精馏设备在实验过程中常出现液泛,漏液等操作异常的情况,且精馏出的产品纯度较低。我们进行了连续精馏和间歇精馏实验,摸索了进料量,进料浓度和回流比对分离效果的影响,并确定该塔适宜的操作条件。实验表明,原料浓度20%,回流比为3可保证连续精馏的稳定进行,且产品浓度可达93.4%;而对于间歇精馏实验,原料浓度25%,回流比4时产品浓度可达95.4%。     

非理想溶液间歇精馏的计算机辅助设计

为了提高二元非理想溶液间歇精馏的设计效率,提出了恒馏出液组成和恒回流比两种间歇精馏操作方式的计算机辅助设计法。采用由智能拟合法得到的汽液相平衡方程逐板计算求理论塔板数,高斯-勒让德数值积分法求有关积分,可视化的Visual Basic 6.0语言编制设计软件。将设计参数输入软件,可快速准确地求出二元非理想溶液间歇精馏的众多设计和操作参数,还可求出回流比与釜液温度的关系,实现由釜液温度前馈控制间歇精馏过程。计算机辅助设计法极大地提高了二元非理想溶液间歇精馏的设计效率。     

间歇减压精馏分离2-甲基吡啶/2-羟乙基吡啶

采用间歇减压精馏法实现了2-甲基吡啶和2-羟乙基吡啶这一热敏性混合物的分离,并考察了投料组成与操作压力对减压精馏过程的影响。结果表明,高真空条件降低了塔釜温度从而避免了物料在塔釜中受热变性,对于热敏物料2-羟乙基吡啶,减压精馏过程中压力应控制在4325 Pa以下,此时塔釜产品2-羟乙基吡啶的质量分数均能大于97%,同时收率能保持在86%以上。在压力为1325 Pa时,不同投料组成下塔顶产品2-甲基吡啶的质量分数和塔釜产品2-羟乙基吡啶的质量分数均高于98%,两者的收率也均在85%以上,能够很好地满足工业生产要求。     

采用回流段的小型精馏装置

介绍具有回流段精馏柱的小型精馏装置 ,它可省去回流控制与回流操作。乙醇—水及丙醇—异丙醇间歇精馏实验表明 ,该装置操作控制简单容易、产品质量稳定、精馏速度快 ,有良好的应用前景。     

Design and control of reactive distillation for ethyl and isopropyl acetates production with azeotropic feeds

Reactive distillations for the production of ethyl acetate (EtAc) and isopropyl acetate (IPAc) are classified as the type-II process where the first column consists of a reactive zone and a rectifying section followed by a stripper [Tang et al., 2005. Design of reactive distillations for acetic acid esterification with different alcohols. A.I.Ch.E. Journal 51, 1683-1699]. Instead of using pure alcohols and acetic acid as reactants, this paper studies the effects of reactant purity on the design and control of reactive distillation. This offers significant economical incentives (by reducing raw materials costs), because ethanol forms an azeotrope with water at 90 mol% and isopropanol/water has an azeotrope at 68%. The purities of the acid is set to 95% for acetic acid (industrial grade), 87% for ethanol, and 65% for isopropanol. The results show that the total annual costs (TAC) increase by a factor of 5% for EtAc and 8% for IPAc production using reactive distillation. Next, the operability of the reactive distillations with azeotrope feeds is explored. Three disturbances, feed flow, acid feed purity, and alcohol feed composition, are introduced to assess control performance using dual-temperature control and one-temperature-one-composition control. Simulation results indicate good control performance can be achieved for reactive distillation with azeotropic feeds.     

硝基氯苯分离提纯工艺的进展和单塔精馏-结晶工艺的推广

硝基氯苯异构物中各组分的提纯工艺经历了3次突破从间歇结晶到连续精馏,从多塔精馏到单塔精馏,成功建立单塔精馏-结晶工艺。单塔精馏-结晶工艺用于新建和改建一批1万～2万t/a的装置。提出现行4500t/a分离装置扩产节能改造方案。     

带有过渡段循环的多元间歇精馏优化计算

采用最大馏出量、最小时间及最大负荷因子作为目标函数,以采出速率作为优化变量,间歇精馏过程采用分段恒回流比操作,利用改进的模拟退火算法进行了带有过渡段循环的三元体系间歇精馏过程的优化。分别获得了3种目标函数下的最优操作条件及最优值,并与文献结果进行了比较。采用改进的模拟退火算法得到的优化计算结果均优于文献值。不同的目标函数下得到的优化操作策略不同,且随着过渡段循环次数的增加精馏过程趋于稳定。     

A generic feasibility study of batch reactive distillation in hybrid configurations

A new graphical feasibility method is developed to investigate batch reactive distillation processes in middle vessel column. The suggested methodology can deal with fully reactive, nonreactive, and complex column configuration. A new formulation is suggested to describe the composition profiles in the reactive sections. Its application has made possible to develop a generic feasibility methodology containing the same model equations independently of the presence or absence of reaction. By combining the reactive and nonreactive models, not only the fully reactive and fully nonreactive but also hybrid configurations can be studied. Feasibility criteria related to the hybrid configurations are also presented. Application of the new methodology is demonstrated on the production of ethyl acetate in batch reactive distillation. Five configurations are found feasible; pure EtOAc is produced as distillate, and pure H₂O is produced at the bottom. In each case, continuous feeding of AcOH is necessary. © 2009 American Institute of Chemical Engineers AIChE J, 2009     

浓度极稀物中回收微量重组分的精馏操作策略—准间歇精馏

A new operation policy--quasi-batch distillation for recovering infinitesimal amounts species existing in a mixture is presented. In quasi-batch distillation operation, feed is introduced with a constant flow rate onto the feed stage of the column, and the flow rate of the distillate is the same as that of the feed, whereas the bottom product is withdrawn periodically. The behavior of quasi-batch distillation is simulated and analyzed through an example on heavy water separation. Comparing with continuous or batch distillation, the new operation policy is more reliable and efficient to achieve higher recovery of dilute component. This is especially suitable for separating small amount of precious species from large amount of raw material.     

浓度极稀物中回收微量重组分的精馏操作策略-准间歇精馏

A new operation policy-quasi-batch distillation for recovering infinitesimal amounts species existing in a mixture is presented. In quasi-batch distillation operation, feed is introduced with a constant flow rate onto the feed stage of the column, and the flow rate of the distillate is the same as that of the feed, whereas the bottom product is withdrawn periodically. The behavior of quasi-batch distillation is simulated and analyzed through an example on heavy water separation. Comparing with continuous or batch distillation, the new operation policy is more reliable and efficient to achieve higher recovery of dilute component. This is especially suitable for separating small amount of precious species from large amount of raw material.     

旋转填料床间歇萃取精馏性能研究

为了寻找强化间歇萃取精馏过程的有效途径,在装填2mm×2mm三角形螺旋填料的旋转床中,以乙醇-水为实验物系,乙二醇为萃取剂,通过考察馏出液组成随时间的变化情况,产品的纯度和回收率随转速、回流比和溶剂比的变化情况,研究了旋转填料床间歇萃取精馏的性能。结果表明,旋转填料床中强大的离心力和高效填料的协同作用极大地强化了间歇萃取精馏过程,具有分离效果好、操作时间短、节能、小设备大生产能力等突出优点;存在最佳转速使产品的纯度和回收率最大;增加溶剂比和回流比均能使产品的纯度和回收率得到提高,但增加溶剂比的效果更显著。旋转填料床是强化间歇萃取精馏过程的有效途径。     

腰果壳油的蒸馏及馏分成分研究

用蒸馏法从商品腰果壳油中提取主成分腰果酚,采用红外光谱、质谱-计算机联用仪对蒸馏馏分进行定性分析。结果表明,常压或减压蒸馏均能得到腰果壳油的主成分,减压蒸馏可大大提高馏分的得率。在真空度0~500 Pa下进行减压蒸馏时,能得到最高得率为77.58%的淡黄色油状馏分,馏分为腰果酚和其它酚类化合物,主馏分腰果酚中带有饱和、单烯、双烯和三烯的长侧碳链。     

Analogues of K = 1 and α = 1 manifolds in multicomponent fractional distillation

Analogues of K = 1 and α = 1 lines for the dynamic systems of batch distillation and continuous fractional distillations at infinite and minimum reflux ratios are considered. Along with singular points, these analogues constitute the structure of phase portraits of the dynamic systems.     

Separation of ethyl acetate–isooctane mixture by heteroazeotropic batch distillation

This paper studies the separation of an ethyl acetate–isooctane mixture by heterogeneous azeotropic distillation in a batch rectifying column. An initial list of 60 candidates was studied but only methanol and acetonitrile were obtained as potential heterogeneous entrainers. These entrainers form a low boiling heterogeneous azeotrope with isooctane. Experimental verification of the miscibility gap with isooctane was performed at 25 °C for each entrainer giving a smaller region for methanol than for acetonitrile. Feasibility of the heterogeneous azeotropic batch distillation was carried out experimentally in a laboratory batch distillation column having 44 theoretical equilibrium stages and using a high reflux ratio. Several distillate fractions were taken as a function of the temperature at the top of the column. For both methanol and acetonitrile, the main fraction was defined by the condensed vapor providing a liquid–liquid split of the isooctane/entrainer heteroazeotrope into the decanter. Ethyl acetate impurity was detected in both decanted phases, but in much lower amount when using acetonitrile as entrainer. The process with acetonitrile also resulted in a shorter operating time and higher purity and recovery yield of isooctane as the main distillate product. Pure ethyl acetate remained into the boiler at the end of each process.     

对叔丁基苯酚连续精馏技术的开发与应用

通过对混合叔丁基苯酚分离过程的模拟计算与设计,开发出了对叔丁基苯酚的连续精馏技术。该技术工业应用结果表明,与传统的间歇精馏技术相比,该技术具有产品含量和收率高、产品质量稳定及能量消耗低等特点。采用连续精馏技术,对叔丁基苯酚生产工艺路线合理,具有推广应用价值。     

Reactive distillation for synthesis of glycerol carbonate via glycerolysis of urea

This study developed a new process for synthesis of glycerol carbonate via glycerolysis of urea by reactive distillation. Missing thermodynamic parameters were estimated by various group contribution methods. The results of Gibbs free energy showed that Gani's method provided the lowest deviation. Equilibrium and kinetic model parameters of the glycerolysis obtained from batch experiments were employed for the simulation of the reactive distillation using Aspen Plus^® software. High conversion of glycerol was achieved by reducing reactant loss in distillate through an increase in the number of stripping and reaction stages and a decrease in the number of rectifying stages. Moreover, glycerol and urea in distillate were recycled to the reactive section by increasing reflux ratio to a reasonable value. The suitable design and operating parameters were achieved at 3 stripping stages, 3 reactive stages, no rectifying stage, reboiler heat duty of 15 kW and reflux ratio of 2. This offered 93.6% conversion of glycerol, and 90.0% yield of glycerol carbonate with 100% purity in the final product. Compared with conventional in vacuo process, reactive distillation promoted glycerol conversion by 29.1% and saved in energy consumption by 37.1%.     

连续流化催化精馏与间歇精馏制备乳酸乙酯的对比研究

乳酸乙酯具有无毒、溶解性好、不易挥发、有果香气味等特点,是极具开发价值和应用前景的"绿色溶剂"。由于乳酸乙酯的特性,国内外学者渐渐致力于开发更高效更环保的制备方法。连续流化催化精馏是利用乳酸和乙醇酯化、粉末状大孔强酸性交换树脂作为催化剂,随反应物流动的连续催化精馏方式,是一种更优的高效而环保的乳酸乙酯生产方式。首次利用连续流化催化精馏制备乳酸乙酯,并旨在研究连续流化催化精馏与间歇精馏制备乳酸乙酯的对比来突出前者的优势,对连续流化催化精馏的产物进行精馏提纯,得到更高纯度的乳酸乙酯,为连续流化催化精馏制备乳酸乙酯的优势提供了可靠的理论依据,并在食品工业等高纯度要求的工业中的运用起到了推进作用。     

萃取精馏分离甲醇-苯

采用萃取精馏的方法分离甲醇-苯的共沸物系。首先采用UNIFAC基团贡献理论并结合经验选取萃取剂,最终确定萃取剂为氯苯。对常压下甲醇 苯物系应用UNIFAC模型计算各组分的汽液相组成,并进行汽液平衡实验验证,计算结果与实验数据吻合较好。通过间歇萃取精馏实验进一步考察验证所选萃取剂的分离效果。结果表明,氯苯能够打破甲醇-苯的共沸,进而分离甲醇和苯。溶剂物质的量之比为1、回流比为3、填料塔理论板数为30、溶剂回收段理论塔板数为4时产品甲醇回收率达到98%,说明氯苯能够作为萃取剂分离甲醇-苯二元共沸物系。最后,对甲醇-苯物系的连续精馏过程应用Aspen Plus进行了模拟计算,并且考察了回流比、萃取剂进料流率等参数对产品纯度的影响规律,为进一步实验研究及工业应用提供理论和实践基础。