萃取精馏分离旋性戊醇与异戊醇

通过试验,研究了萃取精馏中的两个主要参数——回流比和溶剂比,对萃取精馏分离旋性戊醇与异戊醇的分离效果的影响规律,得出了一个较佳的操作条件:回流比为10,溶剂比为4。此研究为实现工业化生产提供设计参数。     

苯-环己烷萃取精馏过程模拟和优化研究

以UNIFAC方程为物性计算方法,使用化工过程模拟系统PRO/对苯-环己烷萃取精馏分离过程进行模拟和优化研究。采用双塔联用工艺,对萃取剂种类、萃取剂用量、温度、加入位置,原料液进料温度、进料位置,两塔的总理论板数分别进行了优化。结果表明:以糠醛为萃取剂,糠醛用量与原料液用量摩尔比为2.2、加入温度为298.15℃、在塔1的第7块板加入,原料液进料温度为353.85℃、在塔1的第25块板进料,塔1的总理论板数为35块,塔2总理论板数为10块时,分离过程达到最优。此时,塔1的环己烷产品纯度为0.9953,塔2的苯产品纯度为0.9890,循环糠醛纯度为0.9985。     

Separation of Ethyl Acetate‐Dichloromethane‐Ethanol by Extractive Distillation: Simulation and Optimization

Chemical process simulation software is adopted to simulate the separation of ethyl acetate‐dichloromethane‐ethanol and water with the aim to use water as the extraction solvent and to meet the requirement of reuse. The influences of solvent ratio, reflux ratio, theoretical plate number, feed position, and solvent position on separation efficiency are discussed. Optimization of orthogonal design and response surface are employed to further optimize the parameters. Relative experimental results prove the reliability of the simulation.     

Modeling,Control, and Optimization of Ideal Internal Thermally Coupled Distillation Columns

Internal Thermally Coupled Distillation Columns (ITCDIC) are the frontier of energy saving distillation research. In this paper, the ideal ITCDIC is considered. A novel mathematical model and a related simulation algorithm are proposed. The dynamic responses of open‐loop, PID controllers and the responses of closed‐loops are carried out. The results show that the ITCDIC is a self‐balance process and could be operated smoothly with two PID controllers; the steady‐state optimization met the need of ITCDIC optimization. Furthermore, a steady‐state optimization model of the operation parameters is presented, which can be used to directly obtain the optimal operation parameters simultaneously guaranteeing not only the product quality and the maximum energy savings but also the dynamic operability and controllability. The benzene‐toluene system is studied as an illustrative example.     

丁二烯分离装置热偶精馏的操作特性

以丁二烯分离装置为对象，对热偶精馏ＴＣＳ－Ｒ用于非理想体系的操作特性和节能效果进行了模拟分析与研究。根据分离要求确定主塔最小馏出的液量后，热偶精馏ＴＣＳ－Ｒ的分离能力和节能效果受汽相连接流股流率的影响最大，其次为汽相连接流股的抽出位置。丁二烯分离装置中应用热偶精馏ＴＣＳ－Ｒ后可以在满足分离要求的前提下节能４０％左右。在此基础上，对这种偶合塔计算了主塔底乙烯基乙炔含量变化对汽相连接流率变化的灵敏度。     

萃取精馏制取均三甲苯的实验研究

在模拟计算的基础上,采用萃取与精馏相结合的装置进行了以C_9芳烃为原料,分离制取高纯度均三甲苯的实验,实验与模拟结果相吻合,为进一步中试提供了可行依据。     

Synthesis and Analysis of Reactive Dividing-Wall Distillation for Methylal Production

By means of water as an extractant, the two-feed and three-feed reactive distillation production processes of methylal are synthesized and analyzed. The effects of water on the methylal reactive distillation (RD) production is investigated. Thermally coupled two-feed and three-feed reactive dividing-wall columns are proposed and analyzed. The two-feed and three-feed RD processes are compared. The three-feed thermally coupled reactive dividing-wall column (DWC) exhibits an outstanding ability of energy and cost savings. Results from this work could be helpful for further development and application of RD or reactive DWC in methylal production.     

Investigating Control Schemes for an Ideal Thermally Coupled Distillation Column (ITCDIC)

The control schemes of an ITCDIC are addressed. A modified IMC scheme (M‐IMC) is proposed to overcome model/plant mismatch of the Internal Model Control scheme (IMC). Predictive PID control (P‐PID) and Adaptive Predictive control (AP‐PID) schemes are also presented to improve effectively the response speed of the multi‐loop PID control (M‐PID) and eliminate its residual error. A detailed comparative investigation on the above five control schemes was performed. Simulation results demonstrate all the schemes are able to keep two end products within their specifications. M‐IMC is the best one with the fastest response speed. AP‐PID is the second choice since it is better at dealing with sudden set‐point transitions and complex external disturbances than P‐PID. M‐PID cannot compete with AP‐PID and P‐PID due to its slow servo response speed and large residual error. IMC ranks last as it is extremely sensitive to changes in the operating conditions.     

Effect of Solvent Content on the Separation and the Energy Consumption of Extractive Distillation Columns

This article sets out to evaluate the effect of solvent content in the extractive section on the separation efficiency and energy consumption of extractive distillation columns. Contrary to the classical approach, the proposed approach enables a simultaneous evaluation of the effect of the major decision variables (reflux ratio, solvent flow rate, and the number of stages of the extractive section [NSE]). The procedure allows calculating the minimum solvent flow rate for the separation and the minimum specific energy consumption. The results show that the minimum specific energy consumption is obtained for the minimum reflux ratio and not for the minimum solvent flow rate. Moreover, the results show that it is not always the case that a larger NSE results in lower energy consumption. Due to its industrial importance, the dehydration of aqueous mixtures of ethanol using ethylene glycol as solvent has been chosen as a case study.     

重整C9芳烃中均三甲苯抽提的实验研究

本文在方法在分析和模拟研究的基础上,采用萃取和精馏相结合的装置进行均三甲苯的抽提试验,验证模拟结果,为进一步中试提供可行依据。     

萃取精馏技术及其在分离过程中的应用

对萃取精馏技术及其在分离过程中的研究与应用进行了讨论。从萃取精馏的基本原理与操作类型、溶剂的物理特性与筛选方法等方面进行了介绍,同时列举了萃取精馏技术在一些物系分离中的应用。最后指出了萃取精馏技术的研究方向。     

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。     

变压精馏及萃取精馏分离乙醇-苯共沸物

使用Aspen Plus分别研究变压精馏及萃取精馏分离乙醇-苯二元共沸物的工艺流程。两种分离流程的塔设备费用相近,萃取精馏工艺较传统变压精馏工艺节能显著,再沸器节能约34%;热集成变压精馏工艺较萃取精馏工艺节能约17.2%,且所需蒸汽品位更低。     

连三甲苯的分离和应用

本文介绍连三苯的分离和应用，以及其工业化后产生的经济效益。     

Design and Control of a Fully Thermally Coupled Distillation Column Modified from a Conventional System

A modified fully thermally coupled distillation column is proposed, with utilization of the existing distillation columns of the conventional system, and its control scheme is suggested here. The proposed distillation system is applied to a benzene‐toluene‐xylene (BTX) separation process, of which the system design and control performance evaluation are conducted using the HYSYS software. The performance of the suggested 3 × 3 control is examined in the set‐point tracking of product specification and the regulation for the changes of feed flow and composition. The pairings of three proportional‐integral control loops are the reflux flow and the specification of overhead product, the prefractionator vapor flow and that of the side product, and the vapor boil‐up rate and that of the bottom product. The multi‐variable controllability using various indices is investigated for the proposed control scheme, and the controllability is compared with that of the cross‐pairing between the control loops of the side and bottom products.     

萃取精馏分离甲醇-甲苯共沸物的研究

利用UNIFAC基团贡献法对常用萃取剂进行了筛选,选取邻二甲苯作为该二元共沸物的萃取剂,并通过汽液平衡实验对其分离效果进行了验证;进行甲醇 甲苯分离的间歇萃取精馏实验考察所选萃取剂的效果。结果表明：邻二甲苯能够有效提高甲醇 甲苯的相对挥发度。间歇萃取精馏塔塔板数为30,溶剂比为1,恒回流比(R=3)操作下塔顶得到摩尔分数为99.688%的甲醇产品。     

萃取精馏分离甲醇和丙酮共沸物

用HYSYS2 2软件对甲醇和丙酮共沸物的萃取精馏过程进行了模拟计算,以水和单乙醇胺(MEA)作为溶剂,通过改变不同的条件:原料进料位置、溶剂比、回流比和溶剂进料温度,得出各自的最佳工艺条件;在模拟的最佳工艺条件下,对以水和单乙醇胺为溶剂萃取精馏分离甲醇和丙酮混合物进行了试验研究,试验结果和模拟计算相吻合,从而验证了模拟的可靠性;并对水和单乙醇胺两种溶剂的萃取精馏特点进行了比较,单乙醇胺的萃取精馏效果比水要好的多。     

萃取精馏分离乙腈-正丙醇的研究

采用萃取精馏的方法分离乙腈-正丙醇的共沸物系。首先利用溶剂选择原理和UNIFAC基团贡献法选出N-甲基吡咯烷酮作为萃取精馏的萃取剂,同时采用NRTL模型对常压下乙腈-正丙醇物系和加入萃取剂N-甲基吡咯烷酮后的汽液平衡进行模拟和实验验证,模拟结果与实验数据吻合较好。然后通过间歇萃取精馏实验进一步考察所选萃取剂的分离效果。结果表明,N-甲基吡咯烷酮能够打破共沸,有效分离乙腈-正丙醇共沸物系。采用有28块理论板的填料塔,萃取剂进料位置为第4块板,溶剂比为1.0,回流比为3,可以从塔顶得到质量分数为98.6%的乙腈产品。最后,用Aspen Plus软件对乙腈-正丙醇物系的连续萃取精馏流程进行了模拟,得出的参数为进一步的工业应用奠定基础。     

硫茚萃取精馏分离的模拟计算

采用Aspen plus软件模拟计算硫茚的萃取精馏,并通过了实验的校核。然后,通过对相同操作条件下不同萃取剂的硫茚萃取精馏模拟,预测了不同萃取剂在实际萃取精馏中的分离效果,选取了合适的高选择性的萃取剂,得到了少量实验的验证,达到事半功倍的效果。     

间歇萃取精馏分离乙腈-水体系

选择乙二醇为分离乙腈-水体系的萃取剂,在压力0.101 MPa条件下,测定了乙腈-乙二醇物系的汽液平衡数据。采用Wilson模型对试验数据进行关联,得到Wilson模型参数,α1,3=5 683.6,α3,1=576.4(下标1代表乙腈,3代表乙二醇),关联的计算结果和试验结果的最大偏差为0.015 7。测定了乙二醇存在下乙腈-水物系的汽液平衡数据,试验结果表明乙二醇做萃取剂能够消除乙腈-水物系的共沸点。进行了乙腈-水物系的间歇萃取精馏试验,回流比为2.0,萃取剂流量与回流量之比(溶剂比)为4.1,塔顶产品中乙腈的摩尔分数x达到0.988,乙腈的回收率为75%。应用Chemcad软件考察溶剂比和回流比对产品纯度及塔顶产品量的影响,确定适宜溶剂比为3.0,其回流比值在0.5~2.0之间。