间歇精馏过程的多目标综合优化研究

为了提高间歇精馏过程的综合效益,需要对间歇精馏过程进行多目标优化。提出了一种基于均匀设计(UD)的间歇精馏过程多目标优化的方法。通过Aspen软件建立模型,均匀设计安排试验方案并进行模型模拟,利用DPS数据处理系统对模拟数据进行二次多项式拟合,得到数学模型并预报最优操作参数,使多目标均能达到最佳优化。并以乙醇-异丙醇二元体系分离过程作为研究案例,得到单程收率为52.92%,操作时间6.52 h,相比初始模型验证实验结果,收率提高24.90%,而操作时间在可接受范围之内,达到了优化效果,为今后间歇精馏过程多目标优化提供一种新的思路。     

间歇精馏过渡馏分脉冲馏出规律研究

建立了二元理想物系考虑全塔持液量的间歇精馏微分形式的数学模型,采用四阶定步长龙格－库塔法对间歇精馏过渡馏分的常规操作和脉冲式操作过程进行模拟计算。实验证明,模拟计算结果与实际符合较好。提出的Ｃ因子概念可用于考察间歇精馏操作效率和经济效益,通过过程模拟,计算了间歇精馏不同操作模式下Ｃ因子的值,并由此分析了不同操作模式的动态规律。     

基于改进模拟退火算法的混合制冷循环天然气流程优化

在研究模拟退火算法的基础上,将模拟退火算法进行改进,采用Ackley函数验证改进的效果.运用模拟退火算法和改进算法分别对混合制冷循环天然气流程进行优化仿真,在对流程参数进行有效优化后,利用该优化流程参数,对整个混合制冷循环天然气流程进行模拟仿真,得出以压缩机耗功与丙烷预冷量之和为最小目标函数的优化流程参数.证明模拟退火算法应用于混合制冷循环天然气流程的可行性和有效性.     

基于流程模拟器和列队竞争算法的精馏操作优化

精馏是高耗能的操作单元,对其进行操作优化是企业实现节能降耗、提高经济效益的有效手段。本文提出列队竞争算法与流程模拟软件相结合的精馏操作优化方法,通过MATLAB-Aspen Plus的接口工具调用Aspen Plus模拟精馏操作过程,得到目标函数值,使用列队竞争算法对其进行操作条件的优化。将所提出的方法应用于某石化企业催化裂化主分馏塔的操作优化,其中目标函数值同时考虑了热能利用与产品分布,优化求解得到了总体效益最大的优化操作方案。     

二元提馏式间歇精馏的优化操作与最小汽化总量

理想操作条件下二元提馏式间歇精馏优化操作的汽化总量与最小汽化总量的计算是约束函数优化问题。本文采用罚函数法,将此约束函数优化转变为无约束函数优化,并采用固定双步长因子梯度法数值求解该函数的极值。计算表明:固定双步长因子梯度法具有良好的收敛性,同时,降低分段数较多时,数值截断误差积累对计算结果的影响。二元提馏式间歇精馏优化操作较恒残液组成操作的能耗低的原因如下:在理论板数相对较少(接近二元提馏式间歇精馏恒残液组成操作所需的最少理论板)时,优化操作通过控制再沸比提高了能耗效率;在理论板数相对较多时,优化操作通过控制再沸比,在保证过程的能耗效率较高的同时,可尽可能快地将物料移出系统,减少了精馏过程中塔顶贮槽内液体的混合熵产。通过对计算结果的归纳与外推,得到了理想操作条件下理论板数为无穷多时二元提馏式间歇精馏优化操作再沸比的变化方式以及最小汽化总量的计算公式。     

间歇精馏脉动馏出方式的研究

对间歇精馏脉动操作在产品馏出段的产品进行了研究,通过实验证可知,所建立的数学 可以较好地描述该操作过程各参数的变化规律。提出了一种以过程分离因子为基础的目标函数,可方便地用于衡量二元间歇精馏不同操作策略产品馏出段的分离效果。     

间歇精馏提纯桃醛工艺综合优化研究

工业上,一般采用间歇精馏提纯桃醛,为了提高工艺的综合效益,需要对间歇精馏过程进行多目标综合优化。首先通过对体系简化方法的讨论,然后建立Aspen模型,经过工业生产验证后,均匀设计安排试验方案并进行模型模拟,利用DPS数据处理系统对模拟数据进行二次多项式拟合,得到数学模型并预报最优操作参数,使多目标达到综合优化。通过优化研究,桃醛单釜收率为59.35%,操作时间30.1 h,相比于验证模型生产结果而言,收率提高了7.13%,操作时间缩短了2.9 h,达到了综合优化的效果,给企业生产带来一定的增效,为今后工业间歇精馏优化提供一种思路。     

基于多目标优化精馏系统综述

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。     

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

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.     

基于Petri Nets优化集成共沸精馏系统方法的应用

基于Petri Nets结构逻辑关系提出共沸精馏系统最优路径集成方法。首先,根据Petri Nets概念拓扑操作单元模块,即精馏、分相与混合模块;然后,建立共沸精馏系统可行操作路径超级结构,从而形成Petri Nets关联矩阵并构造状态方程,考虑最小操作数建立目标函数,进而通过求解0-1整数线性规划,得到分离共沸物最优操作路径;最终,通过实例计算结果与文献的对比,阐述了方法具有超级结构完备,数学模型精确,求解算法高效的优势。     

改进的自适应模拟退火算法及其在过程综合中的应用

为有效解决化工过程综合中的MINLP问题，针对连续变量的模拟退火算法搜索慢的缺点，提出了一种改进的自适应模拟退火算法（Adaptive Simulated Algorithms,ASA)，采取自适应调整温度和搜索步长两种策略，大大加快搜索速度，提高最优解的质量。实算结果充分体现了所提出算法的优点，并很好地应用于化工过程综合问题。     

Multi-objective optimization of seeded batch crystallization processes

The optimization of a batch cooling crystallizer has been traditionally sought with respect to the cooling profile and seeding characteristics that keep supersaturation at an optimum level throughout the operation. Crystallization processes typically have multiple performance objectives and optimization using different objective functions leads to significantly different optimal operating conditions. Thus different temperature profiles and seeding characteristics impose a complex interplay on the crystallizer behavior and there is a trade-off between the performance objectives. Therefore, a multi-objective approach should be adopted for optimization of a batch crystallizer for best process operation. This study presents the solution of various optimal control problems for a seeded batch crystallizer within a multi-objective framework. A well known multi-objective evolutionary algorithm, the elitist Nondominated Sorting Genetic Algorithm, has been adapted here to illustrate the potential for the multi-objective optimization approach.     

分批精馏最小过渡馏份量的研究

提出了分批精馏的最小过渡馏份量概念,导出了最小过渡馏份量的计算方法,通过算例分析讨论了塔板数和塔内存液量对最小过渡馏份量的影响。     

分批精馏过渡段放持液操作方式

The new mode of operation for slop cut withdrawal in batch distillation, i.e., draining Column liquid holdup at the end of slop cut period, was proposed. And the stopping criterion for the operation was investigated, Experiments were carded out with isopropanol-n-propanol binary system and isopropanol-n-propanol-n-butanol ternary system in a distillation column with a liquid collector installed between the reboiler and the column section, Experimental results in a Ф 45mm batch column show that the proposed policy can overcome the flywheel effect caused by column liquid holdup and thus cut down operation time and energy consumption 31%-61%.     

Optimal reflux rate policy determination for multicomponent batch distillation columns

This paper describes a procedure to obtain optimal reflux or optimal distillate rate policy for multicomponent batch distillation columns using the Pontryagin's continuous maximum principle. For application to multicomponent systems, a reduced order model is used using short-cut procedure developed specifically for analysis and design of batch columns.     

DIRECT COMPUTATIONS TO DESCRIBE BATCH DISTILLATION WITH RECTIFICATION

An analog of the Rayleigh Equation has been applied for many years to describe batch distillation with rectification for binary mixtures. A solution is obtained by iterative graphical computations followed by numerical integration. When the batch distillation algorithm is stated in terms of distillate composition a computational non-iterative soluton may be obtained. For a binary separation this expression may be solved on a programmable calculator and the integral may be obtained in segments to describe the progress of the operation expressed in terms of the quantity remaining in the still-pot. This variable is not a linear function of time since even at constant reboiler duty the boil-up rate varies as the still-pot composition changes. If the time rate of the operation is to be determined, this effect must be considered. Procedures have been developed to describe the time-responses of the plate compositions and temperatures, the boil-up rate as well as the conventional variable, the volume remaining in the still-pot

Application of this procedure is illuatrated by evaluating operating strategies for batch distillation. A capacity factor is based on the time required to make a complete separation so that both the distillate product and the heel meet specific composition and disposition of a slop cut (if any) is accounted for. The reboiler is specified to operate at capacity but it is recognized that the boil-up rate will then drop off as the still-pot material becomes heavier and warmer. The distillate composition profiles and the boil up profiles are used to designate changes in objectives during the over-all runs.

Batch processing. The chemical processing industry has been using batch operations increasingly during recent years and these procedures have been drawing increasing attention in chemical engineering publications. Batch distillation is often selected as a significant purification in these processes and has likewise enjoyed a resurgence in investigations and reported advances and results.

Major companies have reported a broad use of batch processing. Chowdhury (1988) has reported that DuPont and Rohm and Haas operate numerous processing lines for hundreds of product variations. Professor G.V. Reklaitis of Purdue has developed a simulation program for designing, scheme selection, and scheduling batch processes and has founded a company, Batch Processing Technologies, Inc. to distribute results from his program.

Batch processing units are most often used in one of two ways. A sequence of equipment may be required to manufacture several different products. This method is often encountered when the products are based on various formulations and rely primarily on mixing and purification to meet customer requirements. Batch processing may also be specified when a particular product is produced from different raw materials and through various processing routes. In either case the same equipment is used repeatedly to perform similar but different operations and is scheduled to operate almost continuously by rapid turnarounds between functions to minimize downtime.     

采用回流段的小型精馏装置

介绍具有回流段精馏柱的小型精馏装置 ,它可省去回流控制与回流操作。乙醇—水及丙醇—异丙醇间歇精馏实验表明 ,该装置操作控制简单容易、产品质量稳定、精馏速度快 ,有良好的应用前景。     

基于样条插值模型的间歇精馏模拟与预测控制

以Aspen Batch Distillation（ABD）中的间歇精馏仿真系统为过程原型,提出了利用过程的模拟测试数据来建立间歇精馏过程的样条插值简化模型（spline interpolation model, SIM）。结合变回流比下的动态修正函数,构造出了一种简单实用的动态模型。该模型可有效模拟不同组分浓度下回流比发生变化时馏出液浓度和流量的动态变化情况。以该模型作为预测模型,进一步提出了一种变回流比的预测控制（model predictive control, MPC）算法来使馏出液浓度按照期望的设定值变化。控制仿真结果表明该控制方案计算简单,同时具有较好的控制效果。     

工业甲醇制备高纯甲醇的间歇精馏模拟与实验

针对工业甲醇制备高纯甲醇的常规间歇精馏过程,建立了恒摩尔持液模型,采用两点隐含和组分衡算相结合的方法进行了求解。模拟分析了影响高纯甲醇收率的产品段回流比、前馏分段回流比和前馏分采出量等因素,并通过实验验证了模型的准确性和可靠性。在实验与模拟计算的基础上,确定了工业甲醇制备高纯甲醇的最佳工艺条件为:总理论板数NT=35,前馏分段回流比R1=10,前馏分的馏出量为原料甲醇投料体积的15%,产品段回流比R2=5,此时产品单程收率为57.1%。     

分批精馏过渡段新型操作方式的研究

提出了一种新型过渡段操作方式———放塔身持液操作,分析了该操作中过渡段结束条件的确定方法,通过实验对过渡段的常规操作方式和放持液操作方式进行了比较,结果表明:后者能有效地克服分批精馏中持液的“飞轮效应”的影响,明显缩短操作时间,降低能耗。该方式操作简单,所需设备易于设计,便于在工业生产中实现,是对传统操作的有效改进。