基于PPSO的精馏塔模型参数闭环辨识

针对粒子群优化算法(particle swarm optimization,PSO)在高维空间复杂曲面寻优时易于陷入局部最小值的问题,分组扰动粒子群优化算法(partially-perturbed particle swarm optimization,PPSO)结合问题特征,采用启发式规则,实施参数分组扰动策略,对PSO算法进行改进,从而增大了跳出局部极小的可能性。本文主要研究PPSO在精馏塔模型参数闭环辨识上的应用,分别针对模型参数可辨识性,参数的不同分组,鲁棒性进行分析验证;并在其他精馏塔模型上进行了相应的验证。仿真实验表明,PPSO辨识算法比序列近似法等其它辨识算法具有更高的辨识精度,并且具有较强的鲁棒性;在其他精馏塔模型参数辨识上PPSO算法也同样取得了很好的辨识精度。实验结果证明了PPSO算法在精馏塔模型参数闭环辨识上的可行性和有效性。

IGCC电站空分系统精馏塔的分段简化模型

针对IGCC电站空分系统精馏塔的逐板模型维数高、计算速度慢的缺点,用分段建模法建立了精馏塔的简化模型。该模型具有物理意义明确、通用性强、计算速度快且结果精确等特点,为进一步实现IGCC电站空分系统的动、静态仿真以及在线优化控制奠定了基础。

基于自动微分的精馏塔优化计算灵敏度分析

提出一种基于自动微分和隐函数求导法则的精馏塔优化计算灵敏度分析方法 ,可以求出精确的、无截断误差的灵敏度系数 ,以反映精馏塔模型中各种不确定因素变化所引起的改变和影响 .精馏塔模型采用的是结合了封闭式和开放式两种建模方式优点的半开放模型 .文中用乙苯精馏塔的优化结果分析验证了该方法的有效性 .通过与差商法的对比 。

多股进料二元精馏图解计算

本文导出具有任意股进料的精馏塔的通用操作线方程式,将McCabe—Thiele法推广到多股进料系统,提出用图解法求算多股进料二元精馏最小回流比以及在y—x图上作出其操作线、确定所需理论板数的方法步骤。

DOWNCOMER MIXING AND ITS EFFECT ON DISTILLATION TRAY EFFICIENCY

In this paper, the measurement of liquid mixing in a downcomer of segmental type of distillation column is presented. The extent of liquid mixing is calculated by means of a mixing pool model. The results indicate that liquid mixing in a downcomer is actually incomplete. It is a significant correction to the assumption of complete downcomer mixing or no downcomer mixing which is generally adopted in many distillation calculations. Besides, the present results are used in a two dimensional eddy diffusion model to calculate the distillation tray efficiency. It is shown that the assumption of complete downcomer mixing is closer to the actual situation than that of no downcomer mixing.

A New Model for the Simulation of Distillation Column

A new computational mass transfer model is proposed for simulating the distillation process by solving the fluctuating mass flux u^＇ic^＇ for the closure of turbulent mass transfer equation in order to obtain the concentration profile and the separation efficiency of distillation column. The feather of the proposed model is to abandon the conventional way of introducing the turbulent mass transfer diffusivity （dispersion coefficient） to the turbulent mass transfer equation. To verify the validity of the proposed model, a commercial scale packed column and a sieve tray column were simulated and compared with published experimental data. The simulated results were satisfactorily confirmed in both concentration distribution and senaration efficiency.

CFD Simulation of Flow and Mass Transfer in Structured Packing Distillation Columns

Detailed investigation of flow behavior in structured packing distillation columns is of great importance in accurate prediction of process efficiency and development of more efficient and optimal equipment internals. In this study, a three-dimensional two-phase flow model based on VOF method for simulating the hydrodynamics and mass-transfer behavior in a typical representative unit of the structured packing is developed. In the proposed model, the c 2 - ε c model is used for the closure of turbulent mass transfer equation. By solving the proposed model, the velocity distribution, phase fraction profile and concentration field are obtained. Using these data, the total liquid holdup, the wetted area and the separation efficiency [height equivalent to a theoretical plate (HETP)] are estimated. For testing the model validation, the simulated HETPs are compared with our previous experimental data obtained in a 150 mm-diameter column containing Mellapak 350Y operating at the pressures of 0.6-1.8 MPa. The compari-son shows that they are in satisfactory agreement, with an average absolute deviation (AAD) of 25.4%.

Methodology for Design of Reactive Distillation Column and Kinetics for Isoamylene Etherification Catalysed by Amberlyst 35

Isoamylene from the Fischer-Tropsch syncrude can be transformed to valuable fuel oxygenate additives through an equilibrium limited etherification reaction with methanol. A reactive distillation process is established to increase isoamylene conversion. Facing the challenge of improving product purity at the same time, an equilibrium stage model based design methodology is proposed and illustrated step-by-step for converting the Fischer-Tropsch C_5 olefins to tert-amyl methyl ether(TAME) process by using Aspen Plus. Under the guide of the proposed methodology, the design leads to a TAME product purity of higher than 95% and an isoamylene conversion of higher than 90%. The etherification kinetics over Amberlyst 35 is also studied within a temperature range of 60 ℃ to 75 ℃ to shed more light on the feasibility of process development. The methodology provides an effective reactive distillation column design to achieve the target reactant conversion and product purity simultaneously.

Modeling of Mass Transfer in Nonideal Multicomponent Mixture with Maxwell-Stefan Approach

The Intalox metal tower packing was used to simulate an industrial relevant extractive distillation column for purifying azeotropic multicomponent mixture.In order to explain the inconsistencies in the modeling of transfer process in nonideal multicomponent distillation column,a method was developed with equilibrium stage models(EQ)and non-equilibrium model(NEQ)incorporated with Maxwell-Stefan diffusion equations in the framework of AspenONE simulator.Dortmund Modified UNIFAC(UNIFAC-DMD)thermodynamic model was employed to estimate activity coefficients.In addition,to understand the reason for the diffusion against driving force and the different results by EQ and NEQ models,explicit investigations were made on diffusion coefficients, component Murphree efficiency and mass transfer coefficients.The results provide valuable information for basic design and applications associated with extractive distillation.

Prediction of Distillation Column Performance by Computational Mass Transfer Method

A computational mass transfer model is proposed for predicting the concentration profile and Murphree efficiency of sieve tray distillation column. The proposed model is based on using modified c＇2 -εc＇ two equations formulation for closing the differential turbulent mass transfer equation with improvement by considering the vapor injected from the sieve hole to be three dimensional. The predicted concentration distributions by using proposed model were checked by experimental work conducted on a sieve tray simulator of 1.2 meters in diameter for desorbing the dissolved oxygen in the feed water by blowing air. The model predictions were confirmed by the experimental measurement. The validation of the proposed model was further tested by comparing the simulated result with the performance of an industrial scale sieve tray distillation column reported by Kunesh et al. for the stripping of toluene from its water solution. The predicted outlet concentration of each tray and the Murphree tray efficiencies under different operating conditions were in agreement with the published data. The simulated turbulent mass transfer diffusivity on each tray was within the range of the experimental result in the same sieve column reported by Cai et al. In addition, the prediction of the influence of sieve tray structure on the tray efficiency by using the proposed model was demonstrated.

Coordinating and Evaluating of Multiple Key Performance Indicators for Manufacturing Equipment: Case Study of Distillation Column

Manufacturing equipment takes the task of operation and directly effects on the manufacturing process. One single Key Performance Indicator （KPI） is mainly employed to evaluate equipment in most studies, neither integrating the KPIs into a completed evaluation system nor considering the impact and conflict among KPIs. In this paper, a KPI evaluation architecture is presented to define and analyze KPIs, and then a common structure for KPI to obtain the KPI set of manufacturing equipment is introduced. An available multi-KPl coordination model is proposed to discern and balance the relationship among multi-KPl. Finally, a case study is introduced to illustrate the applicability of the coordination model by using multi-objective optimization strategy and an efficient solution is obtained.