恒再沸比提馏式间歇精馏的最小再沸流比与能耗分析

通过构造一函数,推导出二元恒再沸比提馏式间歇精馏,在理想操作条件下,理论板数趋向无穷多时,瞬时恒浓区变化方式可由此函数值(>0或<0)来判断,完善了二元恒再沸比提馏式间歇精馏最小再沸比计算方法。推导出二元恒残液组成提馏式间歇精馏,在理想操作条件下的最小汽化总量的计算公式。通过对理论板数趋向无穷多时的能耗分析得到,二元提馏式间歇精馏,要求残液中重组分的收率和平均浓度均高时,相对于恒残液组成操作,采用恒再沸比操作能耗较高,其主要原因是低效总能耗（理论板数趋向无穷多时,直接表现为无效总能耗）在总能耗中占比例较大。     

恒回流比间歇精馏的最小回流比计算及其能耗分析

完善了采用恒回流比操作方法,在理想操作条件下间歇精馏二元理想混合物时,最小回流比的计算方法.分析了采用恒回流比操作方法间歇精馏二元理想混合物,在馏出液中轻组分的收率和平均浓度要求均高时,相对于恒馏出液组成操作方法能耗较高的原因.     

非理想溶液间歇精馏的计算机辅助设计

为了提高二元非理想溶液间歇精馏的设计效率,提出了恒馏出液组成和恒回流比两种间歇精馏操作方式的计算机辅助设计法。采用由智能拟合法得到的汽液相平衡方程逐板计算求理论塔板数,高斯-勒让德数值积分法求有关积分,可视化的Visual Basic 6.0语言编制设计软件。将设计参数输入软件,可快速准确地求出二元非理想溶液间歇精馏的众多设计和操作参数,还可求出回流比与釜液温度的关系,实现由釜液温度前馈控制间歇精馏过程。计算机辅助设计法极大地提高了二元非理想溶液间歇精馏的设计效率。     

基于EXCEL的二元非均相恒沸精馏逐板计算

本文介绍了运用EXCEL逐板计算二元非均相恒沸精馏所需要的理论板数,同时获得各板温度以及汽液组成的方法。此法充分利用了EXCEL强大的函数功能和单变量求解功能完成了计算过程而无需编程,因此具有简单、快速、准确的特点。     

带有过渡段循环的多元间歇精馏优化计算

采用最大馏出量、最小时间及最大负荷因子作为目标函数,以采出速率作为优化变量,间歇精馏过程采用分段恒回流比操作,利用改进的模拟退火算法进行了带有过渡段循环的三元体系间歇精馏过程的优化。分别获得了3种目标函数下的最优操作条件及最优值,并与文献结果进行了比较。采用改进的模拟退火算法得到的优化计算结果均优于文献值。不同的目标函数下得到的优化操作策略不同,且随着过渡段循环次数的增加精馏过程趋于稳定。     

二元精馏图解法求理论板数的几个问题

<正> 在二元精馏的简化计算中,通常用x-y图解法求理论板数和进料位置。但是在现有文献[1,2]中,x-y图解法不能给出进料段中汽、液各流股的组成以及在进料段处精馏段操作线和提馏段操作线的断开位置。本文所推荐的方法避免了上述缺点,从而在x-y图上能较方便地确定出适宜的进料板位置。     

背包式酶催化反应精馏制备丁酸丁酯模拟优化

提出了背包式酶催化反应精馏合成丁酸丁酯的新工艺,将酶催化反应转移到塔外,优化了丁酸丁酯的生产过程。首先,进行丁酸乙酯与正丁醇的酯交换反应动力学实验,建立反应动力学模型,并验证该工艺流程中此模型计算结果的可靠性。然后,运用Aspen Plus对背包式反应精馏新工艺进行了流程模拟和优化设计,分别确定提馏段、精馏段的塔板数,回流比等主要参数。优化后的模拟操作条件为：精馏段塔板数5、提馏段塔板数7、回流比5、侧线循环总量6 kmol/h、侧反应器4个,此时正丁醇的反应转化率能达到99.85%,产品纯度为94.71%,有效减少了设备投资,为背包反应精馏的更优利用提供了理论依据和可行方案。     

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。     

减压间歇萃取精馏分离乙酸乙酯-乙醇过程模拟

间歇萃取精馏是化学工业中重要的分离方法之一,该技术是一种具有分离共沸物及有广泛应用潜力特点的分离技术,变压操作可以改变共沸的组成.减压间歇操萃取精馏可强化共沸物分离,选用N,N-二甲基甲酰胺(DMF)作萃取剂,在UNIFAC相平衡理论的基础上,利用追赶法模拟了二元共沸物减压间歇萃取精馏过程.且通过实验验证了所建数学模型的正确性及计算方法的可靠性.     

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。     

Shortcut Procedure for Inverted Batch Distillation Column (Ⅰ) Multicomponent Ideal System

Inverted batch distillation colunm(stripper) is opposed to a conventional batch distillation column(rectifier). It has a storage vessel at the top and products leave the column at the bottom. The batch stripper is favourable to separate mixtures with a small amount of light components by removing the heavy components as bottom products. In this paper, we are presenting a shortcut procedure based on our earlier work for design and simulation of the inverted batch distillation column, which is equivalent to the Fenske-Underwood-Gilliland procedure for continuous distillation. Given a separation task, we propose to compute the minimum number of stages(Nbmin)and the minimum reboil ratio(Rbmin) required in a batch stripper,which are the stages and reboil ratio required in a hypothetical inverted batch distillation colnmn operating in total reboil ratio or having an infinite number of stages,respectively. Then, it is shown that the performance of inverted batch columns with a finite number of stages and reboil ratios could be correlated in Gilliland coordinates with the minimum stages Nbmin and the minimum reboil ratio Rbmin.     

反置式间歇蒸馏塔的设计程序(Ⅰ)多组分理想物系

Inverted batch distillation column(stripper) is opposed to a conventional batch distillation column(rectifier). It has a storage vessel at the top and products leave the column at the bottom. The batch stripper is favourable to separate mixtures with a small amount of light components by removing the heavy components as bottom products. In this paper, we are presenting a shortcut procedure based on our earlier work for design and simulation of the inverted batch distillation column, which is equivalent to the Fenske-Underwood-Gilliland procedure for continuous distillation. Given a separation task, we propose to compute the minimum number of stages(Nbmin) and the minimum reboil ratio(Rbmin) required in a batch stripper,which are the stages and reboil ratio required in a hypothetical inverted batch distillation column operating in total reboil ratio or having an infinite number of stages,respectively. Then, it is shown that the performance of inverted batch columns with a finite number of stages and reboil ratios could be correlated in Gilliland coordinates with the minimum stages Nbmln and the minimum reboil ratio Rbmin.     

OPTIMAL OPERATION OF BATCH DISTILLATION

The maximum-profit problem in the operation of a batch distillation column separating a binary mixture is studied. From the objective function made in this paper, such problem can be transformed under special condition, into either maximum-distillate or minimum-time problem. Reflux ratio is chosen as control variable. Digital method is worked out by using optimal control theory to find the condition of optimal operation. In deriving present mathematic model, the liquid hold-up in plates and in condenser as well as the plate efficiency are taken into account. The proposed optimal operation is compared theoretically with the conventional constant reflux ratio and constant overhead composition policies and the results show that the proposed optimal operation can lead to/nuch higher profits. To demonstrate the practical usefulness of the proposed optimal policy, experimental work is carried out in a 4 sieve trays 0.17M diameter batch distillation column with ethanolwater system. Agreement is found between the experimental data and the computed results from present model.     

Feasible separations and entrainer selection rules for heteroazeotropic batch distillation

A feasibility analysis is presented for the separation of close-boiling and azeotropic (minimum- and maximum-boiling) binary mixtures into pure components by the addition of an entrainer introducing a heterogeneous azeotrope. The analysis is done for both the conventional batch rectifier and the multivessel batch column. The analysis is theoretical and based on the assumptions of total reflux/reboil ratios and infinite number of stages. Two feasibility conditions are formulated that make it possible to investigate feasibility based on information coming solely from the distillation line map along with the binodal curve of the ternary mixture. Serafimov's classification is used for classifying the azeotropic phase diagrams. The feasibility analysis provides the necessary background and information for formulating rules for entrainer selection for the process. Two simple rules are then proposed, which make it possible to “screen” entrainers for heteroazeotropic batch distillation with minimum efforts.     

二元常规间歇精馏的最小汽化总量

引言 间歇精馏是经常用于小规模生产的一个重要的单元操作,常规间歇精馏的主要特征是间歇精馏过程中塔顶连续出料、塔釜存料,精馏终了塔底集中出料.     

香茅油间歇精馏塔的工艺计算

对300t/a香茅油间歇精馏塔进行物料衡算,根据物料衡算的结果对精馏塔的操作温度、最小理论板数、理论板数、最小回流比、操作回流比和塔径等进行计算,获得塔体的工艺和设备参数。     

Optimal operation of multicomponent batch distillation—multiperiod formulation and solution

A method is proposed to determine optimal multiperiod operation policies for binary and general multicomponent batch distillation of a given feed mixture, with several main products and intermediate off-specification cuts. A two-level optimal control formulation is presented so as to maximize a general profit function for the multiperiod operation, subject to general constraints. The solution of this problem determines the optimal amount of each main and off cut, the optimal duration of each distillation step and the optimal reflux ratio profiles during each production period. The outer level optimization maximizes the profit function by manipulating carefully selected decision variables. These are chosen in such a manner that the need of specifying the mole fractions of all the components in the products, as required by previous methods is avoided. For values of the decision variables fixed by the outer loop, the multiperiod operation is decomposed into a sequence of independent optimal control problems, one for each production step. In the inner loop, a minimum time problem is then solved for each step to generate the optimal reflux ratio values, reflux switching times and duration of the step. The procedure permits the use of very general distillation models described by differential and algebraic equations, including rigorous thermodynamics if desired. The model equations are integrated by using an efficient Gear's type method, the inner loop optimal control problems are solved using a variational method, and all optimisations are solved using a robust and efficient successive quadratic programming code (Chen, Ph.D. Thesis, Imperial College, 1988).

Several example problems (involving binary and multicomponent mixtures) are used to demonstrate the idea and to show the effect of the cost functions used (in particular the value of the main products) on the optimal solutions.     

醋酸-对二甲苯-水体系共沸精馏的模拟分析

采用Aspen Plus11.1化工流程模拟软件,对扬子石油化工有限公司化工厂精对苯二甲酸(PTA)装置的溶剂脱水塔生产过程进行了模拟计算,采用NRTL-HOC热力学计算模型,并进行热力学参数修正,通过调整塔板数、热负荷、进料位置、操作压力、对二甲苯(PX)采出位置等操作参数,得出各塔的最佳工艺条件。在最佳工艺条件下,分析了此分离过程的能耗问题。模拟结果表明,溶剂脱水塔分离得到的醋酸、水、PX均能达到产品质量要求,工艺流程合理、可靠。