多组分复杂精馏流程的简捷设计法

基于对含多个侧线汽提和／或侧线精馏塔的复杂精馏流程的分析,构造了分离五组分的复杂精馏流程。提出了基于流程水平的多组分侧线汽提和／或侧线精馏塔的复杂精馏流程的设计方法。该法不仅可用于多组分复杂精馏流程的优化设计,并且能为复杂精馏流程的严格模拟提供良好的初值,从而为探讨复杂精馏流程的合成提供有效的途径。     

热集成复杂精馏流程综合的随机最优化方法

This paper addresses the application of stochastic optimization approaches to the synthesis of heat integrated complex distillation system, which is characterized by large-scale combinatorial feature. Conventional and complex columns, thermally coupled (linked) side strippers and side rectifiers as well as heat integration between the different columns axe simultaneously considered. The problem is formulated as an MINLP (mixed-integer nonlinear programming) problem. A simulated annealing algorithm is proposed to deal with the MINLP problem and a shortcut method is applied to evaluate all required design paxameters as well as the total cost function. Two illustrating examples are presented.     

基于随机优化的热耦合复杂精馏系统的综合(Ⅰ)模型化方法

基于随机型最优化策略,针对包含简单塔、带有侧线蒸出及侧线汽提塔的复杂塔、全热耦合（或Petlyuk）塔的热耦合复杂精馏塔系统的综合问题,提出一种模型化方法.针对热耦合复杂精馏流程系统所需塔段数目以及冷凝器和再沸器数目的不确定性,提出了一种分解求解策略,将原问题分解成一系列具有不同塔段数的子问题分别求解;针对流程结构的优化提出一种流程结构的编码表达法,该方法将问题的分离序列结构和热耦合方式分别用两组编码表示,对分离序列的编码采用了数据结构理论中的二叉树排序方法,使流程结构的描述变得更加简便;最后以预分馏塔组分回收率及回流比为连续变量,建立了热耦合复杂精馏系统优化的[JP+1]混合整数非线性规划（MINLP）模型,该模型用改进的模拟退火算法求解,可同时得到优化的流程结构和操作参数.     

复杂二元精馏最小回流比的求算

本文推导出复杂二元精馏塔段最小回流比算式,由此可算出各塔段的最小回流比,其中最大值即为塔的最小回流比,最后举例说明了这种求算。     

基于随机优化的热耦合复杂精馏系统的综合（II）计算举例与分析

应用部分(Ⅰ)提出的模型化方法,对多个5组分混合物分离问题进行了求解,以说明方法的实施和有效性.对不同优化方案的优化结果及其经济性做了比较和分析,基于分析结果,对多组分热耦合复杂精馏流程的经济性和设计规则进行了初步归纳.     

用联合算法模拟复杂精馏过程

提出一个复杂精馏过程的通用数学模型,并采用改进的松弛法与修正的N-R法相结合的联合算法求解该模型。通过对理想物系、非理想物系和Petlyuk塔精馏过程的模拟计算,证明该算法通用性强、可靠性高、收敛速度快,模拟结果与文献及工业实验吻合很好。     

相图分析法对共沸精馏流程的改进

共沸精馏是非理想体系的多组分分离。各个因素之间的关系比较复杂,给流程方案的设计增加了难度。现行的共沸精馏流程长、能量消耗大。本文应用三角相图分析法改进了流程。     

二甲苯精馏装置的流程模拟

应用Pro/II流程模拟软件,对年产1014.3 kt二甲苯精馏装置进行流程模拟.选择合理的热力学模型,模拟分析了精馏的温度和浓度分布以及理论板敷,回流比和能耗的关系.模拟结果与实际操作数据吻合较好,说明该软件在二甲苯精馏装置中的应用是可行的,可用于指导生产和设计.     

热敏物系精馏流程优化

采用大型流程模拟软件PRO/Ⅱ,对高沸点差热敏物系乙醇胺的精馏过程进行了模拟,讨论了塔内浓度分布的特点,提出了增加循环物流、侧线出料的优化流程方案,使MEA塔釜温度从168.8℃降至154.5℃,DEA塔釜温度从192.4℃降至175.7℃,显著降低了釜温,防止了釜液中热敏物料的分解,同时产品纯度保持在99%(质量分数)以上.结果表明,对于高沸点差热敏物系的分离,采用上述优化流程能够有效降低釜温,防止热解,并保证产品纯度要求.     

尿素预分离流程改预精馏流程方案探讨

本文在对尿素生产工艺预分离流程与预精馏流程比较的基础上，对贵州化肥厂尿素技改采用预精馏流程的方案进行探讨，并对预精馏塔塔型提出建议。     

Synthesis of flowsheets for extractive distillation of azeotropic mixtures

An algorithm for synthesizing extractive distillation flowsheets for separation of complex ternary azeotropic mixtures with different vapor-liquid equilibrium patterns is proposed.Translated from Teoreticheskie Osnovy Khimicheskoi Tekhnologii, Vol. 39, No. 1, 2005, pp. 19–26.Original Russian Text Copyright © 2005 by Ivanova, Timoshenko, Timofeev.     

Synthesis of partially thermally coupled extractive distillation flowsheets

For sequences involving (i) two-product columns and (ii) partially thermally and materially coupled complexes, algorithms are developed for the exhaustive generation of flowsheets for extractive distillation of n-component mixtures with a single binary azeotrope. The algorithms are aimed at the subsequent development of suitable software. On the basis of the procedure proposed for the construction of extractive distillation flowsheets, catalogues of all flowsheets at n = 2, 3, 4 for case (i) are created. Three recurrence relations are derived for estimating the total number of flowsheets at a specified n, depending on the location of an azeotrope-forming pair in the initial component sequence, when arranged in order of increasing boiling temperatures: at the beginning, end, or strictly inside it.     

Synthesis of separation flowsheets for multicomponent azeotropic mixtures on the basis of the distillation theory. synthesis: Finding optimal separation flowsheets

A general method based on the presynthesis results is suggested for solving the problem of the synthesis of a number of the most advantageous separation flowsheets. The synthesis of optimal flowsheets can be carried out automatically for mixtures with any number of components and azeotropes. Entrainer selection is discussed, as well as the estimation of the separation cost, with the aim of choosing the optimal variant from several preselected ones.     

Application of a new startup procedure using distributed heating along distillation column

This study proposes the use of distributed heating applied to the sieve trays along distillation columns, aiming to evaluate a new experimental configuration and procedure applied to the startup. Through this new configuration it is expected that the column heating time and energy will be reduced. Due to the characteristics of the process, such as inertia and non-linearity, almost all the process variables change rapidly, which increases the time required to reach the steady state. These factors make the objective of this study even more challenging. Most of the previously published studies on startup involve simulations, whereas the main contribution of this paper is that it provides experimental results. The experiments were carried out on a pilot distillation column with 13 sieve trays processing a binary mixture composed of water and ethanol, with a flow rate of 300 L h^?1 in the fourth tray. It was verified that the use of a heating system which is able to act in a distributed way allows a reduction in the time (40%) and energy (33%) required for the startup procedure, compared to a conventional approach.     

A boundary value design method for complex demethaniser distillation columns

Typically the number of design options for demethaniser flowsheets, that recover methane from a gas mixture, is large. Repetitive simulations, to evaluate the economic viability of alternatives, do not usually enable a thorough exploration of the variable space for the purposes of process synthesis. More comprehensive process optimisation is facilitated by shortcut design models and a suitable optimisation framework. These optimisation results, applying shortcut models, are useful at the initial design stage, when the range of flowsheet options and operating conditions to be explored is relatively wide.A demethaniser column has many degrees of freedom, including the operating pressure, the location and the order of feeds, the number and duty of side reboilers and the flow rate of the external reflux stream. The complexity of the demethaniser column precludes the use of the Fenske-Underwood-Gilliland shortcut design method. An appropriate design model for the demethaniser is presented for application within an optimisation framework for process synthesis and evaluation. The column design model is computationally relatively undemanding, yet accurate, so should allow evaluation of both energy demand and equipment requirements.The design model presented is a semi-rigorous boundary value method for the design of complex demethaniser columns separating multicomponent mixtures. The method has been implemented within MATLAB and linked to HYSYS for prediction of physical and thermodynamic properties. Industrially relevant examples demonstrate that the results of the proposed design methodology are in good agreement with those of rigorous simulation.     

A systematic procedure for synthesis of intensified nonsharp distillation systems with fewer columns

Nonsharp separation sequences can intrinsically improve thermodynamic efficiency than that of sharp sequences for a multicomponent distillation. There are much more nonsharp sequences than that of sharp sequences. In this paper, the synthesis of new intensified distillation systems from nonsharp separation sequences is presented. Such intensified distillation systems have fewer columns and have the potential to reduce both energy and capital costs than conventional configurations. First, the representation of any nonsharp sequence with the simple column configuration is found to be the necessary starting point. Then, five strategies are introduced which present different mechanisms to change the structures of the distillation configurations. Third, a systematic procedure is formulated which can achieve the intensified distillation systems with fewer columns systematically. Finally, the systematic method has been applied to different examples of nonsharp separation sequences. It is demonstrated that the method can be used to generate the new intensified distillation systems from any nonsharp separation sequences. The method is easy to use and can explicitly derive all of the intensified distillation systems for the nonsharp separation sequences for a multicomponent distillation.     

A design procedure for heat-integrated distillation column sequencing of natural gas liquid fractionation processes

The separation of NGL (natural gas liquids) in gas processing is energy-intensive, requiring systematic process design and optimization to reduce energy consumption and to identify cost-effective solutions for the recovery valuable hydrocarbons. As NGL fractionation processes require a sequence of distillation columns to separate multi-component mixtures the determination of optimal energy-efficient distillation sequences and operating conditions is not a simple task. A design methodology is proposed in this study in which the process simulator Aspen HYSYS^® is linked with an optimization algorithm available in MATLAB^®. The proposed methodology involves a procedure where in the first step possible distillation sequences are screened using a short-cut distillation column model. In the second step a few selected and promising candidate distillation sequences are further simulated and optimized, again using the same short-cut model. Finally, rigorous simulations are used to validate and confirm the feasibility of the optimal designs. A case study is presented to demonstrate the applicability of the proposed design framework for the design and optimization of NGL fractionation processes in practice.     

A rapid method of approach to complex distillation problems

The method combines slide-rule procedure with graphical plots. Where deviations from ideality have to be taken into account, the approximate magnitude of their effect can be ascertained relatively quickly. In the event that precise plate-to-plate computations are proceeded with, these can be commenced under conditions which are already approximately correct ; thereby shortening these often very lengthy and involved computations.