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This work has developed a simple, reliable and fast algorithm for the simulation of multicomponent distillation columns, where any equilibrium stage can accept a feed-stream and/or a vapor-side-stream and/or liquid-side-stream. The new scheme considers internal molar overflows and constant relative volatilities to avoid the need of heat balances and vapor–liquid equilibrium calculations. The solution scheme is founded on a Newton-based formulation in block algebra, which relies in a simple, reliable and fast algorithm. Although the proposed calculation scheme can be classified as an approximate method, it is very useful when accurate phase equilibrium and enthalpy data are lacking. Numerical experimentations show good agreement with the results obtained with well-known rigorous simulation approaches. 相似文献
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本文提出了用于液液萃取与精馏塔网络模拟的数学模型和解法.此法采用牛顿-拉夫森迭代技术,结合适当的阻尼因子并用简化模型的解作为此严格计算的初值.模拟中除选用一组基本的设计变量外,还可将迭代变量或(和)非迭代变量与这些基本的设计变量互换,以满足设计要求.以从含酚污水中回收苯酚为实例说明了此严格计算法.结果是满意的. 相似文献
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Heterogeneous distillation processes are widely used in industry for the separation of azeotropic and close-boiling mixtures. This paper addresses the optimization of a heterogeneous distillation process for the separation of an azeotropic ethanol/water mixture using cyclohexane as an entrainer. Starting from a given process superstructure a MINLP problem is set up to consider continuous as well as discrete decision variables such as the feed locations and the number of stages of the distillation columns. A modified Generalized Benders Decomposition algorithm to account for non-convexities of the model equations solves the MINLP problem. The algorithm can be attached via Visual Basic for Applications (VBA) to any commercial process simulator with NLP and VBA capabilities. Various optimization runs show that the algorithm is easily applicable and returns solutions independent of the initial values. 相似文献
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EXACT CALCULATION METHODS OF INTERLINKED COLUMN SYSTEM——SIMULATION OF RECOVERY OF PHENOL FROM WASTE WATER CONTAINING PHENOL 下载免费PDF全文
This paper describes a mathematical model and an algorithm which can be used for simulation of in-terlinked column systems consisting of liquid-liquid extraction and distillation.This algorithm is basedupon Newton-Raphson iteration technique using suitable damping factors and solutions of simplified modelas initial values of exact calculations.With the exception of principle specification it is possible to interchangethe iteration variables and/or noniteration variables with design variables to meet requirements of design.A process of recovery of phenol from waste water containing pheonol is illustrated to varify the model andalgorithm.The results are satisfied. 相似文献
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Kaj Jakobsson Antti PyhälahtiSini Pakkanen Kari Keskinen Juhani Aittamaa 《Chemical engineering science》2002,57(9):1521-1524
A new software tool to simulate and optimise processes that combine distillation column with a reactor sequence has been developed. This kind of combination is particularly interesting when new intensified and integrated processes are developed. The unit block contains both the distillation column model and the models for the coupled reactors. The model equations are solved simultaneously in one block and not sequentially as it is done when the reactor/distillation systems are solved by present flowsheet programs. This software module has been implemented into a flowsheet simulator environment that contains all required physical and chemical data banks and enables large-scale process optimisation. The applicability of the new module is demonstrated by solving two presently interesting processes: production of MTBE and isooctene. The model has shown good convergence properties. 相似文献
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热偶精馏过程模拟优化方法的改进——人工神经网络-遗传算法 总被引:3,自引:2,他引:1
采用人工神经网络和遗传算法对热偶精馏分离过程提出了一种新的建模方法和优化算法,该方法不仅能够有效地求解热偶精馏过程的数学模型,迅速地得到优化变量和目标函数的解,而且具有获得全局最优解的能力.最后通过实例说明了本方法的有效性. 相似文献
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采用演化算法求解具有组合爆炸特征的精馏分离序列优化综合问题。由于精馏分离序列与二叉树之问具有同构性.在数据结构上精馏分离序列可以抽象为二又树,直接采用二叉树结构编码方案可以同时表达个体的基因型和表现形。借鉴生物界父本可以经过有性繁殖或无性繁殖得到子代的现象。对遗传算子进行设计。应冒图论方法建立有效的二叉树结构演化重组机制,从而形成基于双亲或单亲父本的交叉算子。实例表明:双亲遗传操作其空间搜索率较低,而单亲遗传操作其最优解命中率较高。因此。演化算法能够成功解算大规模精馏分离序列优化综合问题。 相似文献
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A globally convergent method for finding all steady‐state solutions of distillation columns 下载免费PDF全文
A globally convergent method is proposed that either returns all solutions to steady‐state models of distillation columns or proves their infeasibility. Initial estimates are not required. The method requires a specific but fairly general block‐sparsity pattern; in return, the computational efforts grow linearly with the number of stages in the column. The well‐known stage‐by‐stage (and the sequential modular) approach also reduces the task of solving high‐dimensional steady‐state models to that of solving a sequence of low‐dimensional ones. Unfortunately, these low‐dimensional systems are extremely sensitive to the initial estimates, so that solving them can be notoriously difficult or even impossible. The proposed algorithm overcomes these numerical difficulties by a new reparameterization technique. The successful solution of a numerically challenging reactive distillation column with seven steady‐states shows the robustness of the method. No published software known to the authors could compute all solutions to this difficult model without expert tuning. © 2013 American Institute of Chemical Engineers AIChE J 60: 410–414, 2014 相似文献
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从结构优化角度建立精馏塔优化的混合整数非线性规划(MINLP)模型,为了消除整数变量,引入绕流效率将MINLP问题转化为非线性规划(NLP)问题。针对得到的NLP问题提出一种优化方法,在该方法中采用结构优化中常用的信赖域优化算法进行求解,并应用虚拟瞬态连续性方程辅助优化中的稳态模拟。采用提出的优化方法对3个精馏系统进行设计优化,以不同初始值开始,均可得到令人满意的优化结果,表明所提优化方法具有良好的稳健性,对于较复杂的部分热耦合精馏过程仍然可以有效优化求解;信赖域算法在精馏塔优化中也表现出良好的收敛性。 相似文献
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In this paper, a new approach using artificial neural network and genetic algorithm for the optimization of the thermally coupled distillation is presented. Mathematical model can be constructed with artificial neural network based on the simulation results with ASPEN PLUS. Modified genetic algorithm was used to optimize the model. With the proposed model and optimization arithmetic, mathematical model can be calculated, decision variables and target value can be reached automatically and quickly. A practical example is used to demonstrate the algorithm. 相似文献
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In this paper, we propose a novel algorithm for the rigorous design of distillation columns that integrates a process simulator in a generalized disjunctive programming formulation. The optimal distillation column, or column sequence, is obtained by selecting, for each column section, among a set of column sections with different number of theoretical trays. The selection of thermodynamic models, properties estimation, etc. is all in the simulation environment. All the numerical issues related to the convergence of distillation columns (or column sections) are also maintained in the simulation environment. The model is formulated as a Generalized Disjunctive Programming (GDP) problem and solved using the logic based outer approximation algorithm without MINLP reformulation. Some examples involving from a single column to thermally coupled sequence or extractive distillation shows the performance of the new algorithm. 相似文献
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综述了精馏系统中多目标的优化问题,分析列举了人工神经网络、正交设计、响应面、遗传算法和粒子群算法在精馏系统多目标优化中的应用,旨在总结精馏系统中的优化算法,寻求最优操作条件的解法,为精馏塔的多目标优化提供参考。结果表明,针对于目前精馏系统的复杂多变性及混合规划问题,这些算法可以很好地对精馏系统进行建模,预测精馏模型,预测值与模拟值拟合较好,有较高的精度。且可用于求解精馏过程中的最优操作条件,降低系统的不可逆性,实现了精馏系统的节能优化,提高了产品质量,降低了能耗。最后指出了多目标优化精馏系统方法的可行性,也表明在实际生产中将多种优化算法相结合进行多步优化的可行性。 相似文献
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The detailed techniques for improving the efficiency of a fault-diagnosis algorithm can be based on the signed directed graph. This graph represents the structure of the system, and the pattern on the graph represents a state of the system. The usefulness of the improved algorithm is demonstrated using a model of a chemical process comprising a reactor, a heat exchanger and a distillation tower. 相似文献
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This paper presents a flexible solution method for the process design and simulation of generalized equilibrium stage absorption or distillation columns for solving a wide range of multistage, multicomponent separation problems in the petroleum or petrochemical industries. Although the model was developed to increase the control flexibility of product components in a solution, it was found that it also increases the efficiency of convergence at the expense of greater core usage. The mathematical model includes overall material balances, component material balances, energy balances, summation equations and specification equations. These nonlinear equations are solved simultaneously via the matrix partitioning technique together with the popular Newton-Raphson iterative algorithm. The method is applicable for both absorption and distillation columns with multiple feeds and sidedraws. This model will offer more flexible choices of the column specifications such as tray temperature, overhead product rate, reflux ratio, boilup ratio, tray vapor/liquid flow and product purity/recovery. The composition dependent equilibrium and enthalpy correlations such as Chao-Seader, Grayson-Streed, and Soave-Redlich-Kwong are incorporated into the mathematical model. Most problems can be easily converged with less than ten iterations. 相似文献
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Cyclic distillation uses a periodic operation mode that leads to key benefits, such as increased column throughput, lower energy requirements and much higher separation performance. By integrating chemical reactions with cyclic distillation, a novel process intensification approach is possible – catalytic cyclic distillation – which outperforms classic reactive distillation.This paper is the first to describe the catalytic cyclic distillation process and to develop a rigorous mathematical model. By means of a case study involving a simple reaction system, the model is used to demonstrate the key benefits of this operation mode. In addition, the synthesis of dimethyl ether by catalytic cyclic distillation is considered, for which a design algorithm is suggested. Investigation of the column behavior reveals the coexistence of two periodic states, one of them being unstable. 相似文献