Systematic screening procedure and innovative energy-saving design for ionic liquid-based extractive distillation process

In the traditional extractive distillation process, organic solvents are often used as entrainers. However, environmental influence and high energy-consumption are significant problems in industrial application. In this study, a systematic screening strategy and innovative energy-saving design for ionic liquid-based extractive distillation process was proposed. The innovative energy-saving design focused on the binary minimum azeotrope mixtures isopropanol and water. Miscibility, environmental impact and physical properties (e.g., melting point and viscosity) of 30 ionic liquids were investigated. 1-Ethyl-3-methyl-imidazolium dicyanamide and 1-butyl-3-methyl-imidazolium dicyanamide were selected as candidate entrainers. Feasibility analysis of these two ionic liquids was further performed via residue curve maps, isovolatility line and temperature profiles. An innovative ionic liquid-based extractive distillation process combining distillation column and stripping column was designed and optimized with the objective function of minimizing the total annualized cost. The results demonstrate that the total annualized cost was reduced by 19.9% with 1-ethyl-3-methyl-imidazolium dicyanamide as the entrainer and by 24.3% with 1-butyl-3-methyl-imidazolium dicyanamide, compared with that of dimethyl sulfoxide. The method proposed in this study is conducive to the green and sustainable development of extractive distillation process.     

Thermodynamic optimisation of distillation columns

In this paper a methodology for thermodynamic analysis and distillation column ‘targeting’ is presented, with emphasis on the use of side condensers and side reboilers. Research in the past has been towards the establishment of a heat distribution curve, showing the way in which heat can be added or extracted across the different column sections. One major disadvantage of these profiles is that they refer to reversible columns, and cannot be used effectively to target for modifications in a real column.The main feature of the proposed methodology is the introduction of a minimum driving force, defined in terms of exergy loss distribution of the existing column, to set realisable targets for side reboiling/condensing in real columns, resulting in considerable energy savings. In addition to providing realisable targets, the new approach also provides the design engineer with information about the best location to place a side exchanger, and the required additional column modifications. The methodology can be applied using conventional column models in commercial process simulation programs, but can be significantly simplified by using reboiled and refluxed absorber models in a bespoke program. Simulation results for modified designs set by the new approach, for binary and multicomponent separations, verify the feasibility of the targets. This contrasts with previous approaches, which result in temperature shifts and heat load penalties after placing side reboilers/condensers, thus requiring additional simulation time and experienced judgement.     

基于遗传规划的复杂精馏系统综合

提出了基于遗传规划的复杂精馏系统的综合方法.针对复杂精馏系统特点并结合化工领域知识,对遗传算子进行了改进,给出了一套独特的编码方法和求解策略.算法利用层次化结构来直观地表达复杂分离流程,同时解决了其他随机算法编码在表达精馏过程时的歧意性问题.在不必给定精馏系统超结构的情况下,能够完成可行域的自动搜寻.实例计算表明,基于遗传规划的综合策略可以用于求解复杂精馏系统的最优综合问题,实现了包括侧线塔、完全热偶塔及同时考虑热集成的各种复杂精馏结构的自动搜索寻优.     

Synthesis of heat-integrated complex distillation systems via Genetic Programming

This paper addresses the application of Genetic Programming (GP) to the synthesis of heat-integrated complex distillation system and the flowsheet of complex separation can be expressed directly using GP's special hierarchical structure. A series of unique encoding method and solution strategy is proposed and some evolutionary factor is improved based on the domain knowledge of chemical engineering. A shortcut method is applied to calculate all required design parameters. Conventional and complex columns, thermally coupled (linked) side strippers and side rectifiers, fully thermally coupled columns as well as heat integration between any different columns are simultaneously considered. Two illustrating examples are presented to demonstrate the effective computational strategies.     

Synthesis of complex thermally coupled distillation systems including divided wall columns

The design of thermally coupled distillation sequences explicitly including the possibility of divided wall columns (DWC) is described. A DWC with a single wall can be considered thermodynamically equivalent to a fully thermally coupled (FTC) subsystem formed by three separation tasks (a Petlyuk configuration in the case of three‐component mixtures). It is shown how to systematically identify all the sequences of separation tasks that can produce configurations that include at least a DWC. Feasible sequences that explicitly include DWCs are enforced through a set of logical relationships in terms of Boolean variables. These logical relationships include as feasible alternatives from conventional columns (each column must have a condenser and a reboiler) to FTC systems (only one reboiler and one condenser in the entire system). A comprehensive disjunctive programming formulation for finding the optimal solution is presented. The model is based on the Fenske, Underwood Gilliland equations. However, the disjunctive formulation allows easily the use of any other shortcut, aggregated or even rigorous model without modifying much the structure of the model. Two illustrative examples illustrate the procedure. © 2012 American Institute of Chemical Engineers AIChE J, 59: 1139–1159, 2013     

Analytical screening criterion for sequencing of distillation columns

This paper is concerned with the development of a quantitative criterion based on the total interstage flowrate in a distillation column. This criterion reflects the total optimum cost of a column and can be used for screening simple column sequences. It has been shown that the interstage flowrate measure is compatible with known heuristics and the results have been compared with those obtained from other methods in the literature.     

膜蒸馏分离技术研究进展

综述了膜蒸馏技术的基本原理与膜蒸馏形式、研究历史与现状、传质机理与模型以及最新应用情况,并对其存在的问题和应用前景作了分析。     

微尺度蒸馏技术的研究进展

随着电子学的发展和微制造技术的不断进步,微尺度蒸馏技术作为一种有效的化工强化手段,可用于解决蒸馏工艺存在的设备庞大、能量利用效率低以及对于相对挥发度较低的体系分离困难等问题。当尺度减小后,液体通道的深度和传质距离也随之减少,气-液或液-液间的传质效率显著增强。利用微蒸馏设备进行分离具有极低的等板高度;同时,在具有优良控温系统的前提下可以对传热进行更精准地控制,有利于减少热敏体系中副反应的发生。本综述分别介绍了重力微蒸馏、载气微蒸馏、真空微蒸馏、毛细(管)力微蒸馏和离心力微蒸馏五种主要的微尺度蒸馏方法,比较和讨论了每种方法的结构特征及其优缺点,并对微蒸馏设备的加工制造技术进行了系统介绍。微尺度蒸馏技术具有特殊的优势,能够为现代化工蒸馏向着降耗、环保、集约化的目标发展提供新思路。     

精馏分离技术研究新进展

本文在参考大量文献的基础上,着重介绍了各种精馏方法以及国内外发展状况,对萃取精馏和恒沸精馏方法进行比较,并对催化精馏技术的国内外研究进展做了详细介绍.     

分子蒸馏技术分析

分子蒸馏技术是近几十年发展起来的一种先进的液液分离技术。介绍了分子蒸馏技术的基本原理及其有别于一般蒸馏技术的特点:操作温度远低于液体沸点,蒸馏压力在极高真空度下,受热时间短。还介绍了分子蒸馏器的设备结构和设计要点、分子蒸馏技术在工业中的应用范围以及国内外发展概况,并提出分子蒸馏技术工业化应用中存在的问题及解决方法。     

分子蒸馏技术及应用

分子蒸馏技术是高纯材料制备的瓶颈技术,一直备受各国重视.本文介绍了国内外分子蒸馏技术的发展概况及其应用特点,结合实际应用的要求,对分子蒸馏的技术理论、分子蒸馏分离过程以及在精细化工、医药、高纯度物质、超分子化合物制备等方面的应用前沿,做了较全面而详细的介绍.     

Orbital tube evaporator and distillation systems

The Orbital Tube Evaporator (OTE) was inspired 10 years ago by the emerging technology of the horizontal tube evaporator (HTE). Recent market share (1985–June 1986) of H.T.E. for large land based systems is an impressive growth of 10% from its all time total of 3% (3.3 to 1) as against 48% from 28% (1.7 to 1) for all types of membrane systems and the declining position of 42% from 64.5% for the industrial standby, the multi-stage Flush (MSF) type. (Table II)In either the multi-effect boiling (MEB) or the vapor compression (VC) system configurations, O.T.E. plays essentially the same role as the HTE or the Vertical Tube Evaporator (VTE), but with much higher heat transfer coefficient, higher output purity without the need of demister and less tendency to scaling or fouling. Several engineering models were developed to substantiate its various performances and to simplify the mechanical design for practical application.The superior features of the OTE are derived from an inertially coupled whip rod revolving inside each tube to spread the fluid into thin and uniform film to fascilitate the heat transfer, while allowing the main stream of the throughput to flow down the tube freely. This division of the heat transfer and the mass transfer of the fluid permits the reduction of the dwelling time and assures an even temperature distribution of the fluid quite similar to the wiper evaporators, but without their troublesome seals and mechanical drive mechanism inside the evaporation chamber.The excellent showing of the HTE in the desalination market provides a strong encouragement for further development and adaptation of the OTE for desalination systems of various sizes and configurations. In addition, OTE may also be used for the production of pure water for pharmaceutical or electronic chip manufacture, or for the distillation of other kinds of fluids.Furthermore, OTE as a concentrator can be more cost effective than either the wiper type or the falling film type for a number of applications. Since the OTE is quite simple in system configuration, a successful field test in any one of the above applications would facilitate its adaptation to other systems.     

催化蒸馏技术的应用进展

综述了催化蒸馏技术的应用进展情况，介绍了催化蒸馏技术的特点及装填方式，并从醚化、酯化，烷基化、缩合等几个方面简要叙述了近年来催化蒸馏技术的应用与发展。     

Note on flash and distillation systems

Flash and distillation systems evolving on the equilibrium manifold possess stable steady states when the molar flows and the boundary conditions are fixed and a vapor and liquid phase is present at all times. The results extend the range of validity of a local stability theorem for linear, constant molar overflow systems due to Acrivos and Amundson. The approach to stability analysis is motivated by the tangent plane method developed by Gibbs to open systems as it takes advantage of the negative curvature of the entropy surface to construct a Lyapunov function. © 2013 American Institute of Chemical Engineers AIChE J, 59: 3322–3332, 2013     

新型精馏集成技术用于混合硝基氯化苯分离的研究

介绍了硝基氯苯3种同分异构体的性质、用途及生产现状,分析了混合硝基氯苯分离的难点,对目前已有的分离方法进行了综述,指出了各种分离方法的优点和不足。提出了侧线精馏-萃取精馏-结晶相结合的新型精馏集成技术用于混合硝基氯苯的分离,与传统工艺相比,该过程工艺简单,分离效率高,分离的能耗大大降低。     

膜蒸馏处理石化高盐废水技术研究

以石化高盐废水为实验体系,采用现有疏水膜,考察了各种膜蒸馏耦合工艺对石化不同高盐废水体系的处理效果,验证了膜蒸馏耦合工艺用于石化高盐废水体系的适用性。     

Storage composites for the optimisation of solar water heating systems

Composite materials based on expanded natural graphite (CENG) and various phase change materials (PCM) have been developed for low temperature solar applications (323–373 K). The integration of such composite materials directly into the solar collector could allow new storage functionality. A numerical model has been developed to describe the materials behaviour. Composites properties are presented and discussed.     

Stochastic screening and scoping of separation sequences using detailed simulation models

The paper presents stochastic optimisation technology as applied on separation sequencing problems. Simulated annealing is employed along with a synthesis representation in the form of a dynamic vector. Permutations on the vector and perturbations on the current state generate new sequences and layouts that are accessed, accepted and rejected. The approach can handle problems of industrial complexity. Operational variables (pressures, reflux ratios, product composition) can be optimised simultaneously with the structure. The potential of the methodology is illustrated with an FCC example.