周期全回流间歇精馏中全采出操作时的塔顶浓度平台期(英文)

The total withdrawal operation is an inevitable section in cyclic total reflux batch distillation.In the operation,an interesting phenomenon "overhead concentration platform"(OCP) appears,which is defined as a period of time with high overhead concentrations when the operation is changed from total reflux to total withdrawal.The OCP phenomenon and its influential factors,such as the theoretical stage number,feed concentration,and feed composition,are examined by simulations and experiments.The experimental equipment is a column with random packings.It is shown that the number of theoretical stages influences the OCP more significantly than the other factors.     

周期操作全回流间歇精馏的动态模型(英文)

Cyclic total reflux (CTR) batch distillation is a promising mode of the process but lacking of appropriate modeling for the period of filling the reflux drum. A new dynamic modeling method for the simulation of CTR batch distillation is proposed in this work, in which the changes in column holdup and liquid flow rate during the filling of the drum, and the consequent change in valid number of theoretical plates are considered. The effect of drum holdup on operation time is investigated and the optimal drum holdup is obtained from the simulation. The dynamic modeling is compared to the conventional modeling without consideration of change in liquid flow rate. The experimental result shows that the present modeling is more reliable and more accurate, especially for the col-umn with large liquid holdup.     

拟稳态模型用于间歇萃取精馏的数值模拟

Batch extractive distillation (BED) is a special method used in the distillation process by adding a solvent into the batch distillation column to alter the relative volatility of the components and improve the separation. A comprehensive design and simulation method is required due to the complexity of BED. In this study, a quasi-steady-state model for BED is proposed, the derivation and solution of the model are presented. This shortcut model can be used to simulate the composition and temperature of the reboiler, the top and other plates of the column in a batch extractive distillation operation. The calculated values are in good agreement with the experi-mental data. The results show that the quasi-steady-state model is a practical method because of some advantages such as high precision and fast calculation.     

内部热耦合精馏塔基于非理想物系的最优评价

Internal thermally coupled distillation column(ITCDIC) is a frontier in energy saving distillation research. In this paper, the optimal assessment on the energy saving and the operating cost for ITCDIC of nonideal mixture is explored. An evaluating method is proposed, and the pertinent optimization model is then derived. The ethanol-water system is studied as an illustrative example. The optimization results show that the maximum energy saving in ITCDIC process is about 35% and the maximum operating cost saving in ITCDIC process is about 30%,as compared with a conventional distillation column(CDIC) under the minimum reflux ratio operating; the optimal operating pressure of the rectifying section is found to be around 0.25 MPa; the effects of the feed composition,operating pressure and the heat transfer rate on operation are also found and analyzed. It is revealed that ITCDIC process possesses high energy saving potential and promising economical prospect.     

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.     

Process optimization of an industrial acetic acid dehydration progress via heterogeneous azeotropic distillation

The simulated process model of the HAc dehydration process under actual overloaded condition was conducted by amending the model of standard condition in our previous work using the process data collected from actual production. Based on the actual process model, the operation optimization analysis of each plant(HAc dehydration column, decanter and NPA recycle column) was conducted using Residue Curve Maps(RCMs),sensitivity analysis and software optimization module. Based on the optimized parameters, the influence of feed impurity MA and the temperature of decanter on the separating effect and energy consumption of the whole process were analyzed. Then the whole process operation optimizing strategy was proposed with the objective that the total reboiler duty Q Total of C-1 and C-3 reaches the minimum value, keeping C-1 and C-3 at their optimized separation parameters obtained above, connecting all the broken recycle and connection streams, and using the temperature of D-1 as operation variable. The optimization result shows that the total reboiler duty Q Total of the whole process can reach the minimum value of 128.32 × 10~6 k J·h~(-1) when the temperature of decanter is 352.35 K, and it can save 5.94 × 10~6 k J·h~(-1), about 2.56 t·h~(-1) low-pressure saturated vapor.     

苯氯化侧反应精馏过程的系统设计与控制(英文)

The distillation column with side reactors (SRC) can overcome the temperature/pressure mismatch in the traditional reactive distillation, the column operates at temperature/pressure favorable for vapor-liquid separation, while the reactors operate at temperatures/pressures favorable for reaction kinetics. According to the smooth operation and automatic control problem of the distillation column with side reactors (SRC), the design, simulation calculation and dynamic control of the SCR process for chlorobenzene production are discussed in the paper. Firstly, the mechanism models, the integrated structure optimal design and process simulation systems are established, respectively. And then multivariable control schemes are designed, the controllability of SRC process based on the optimal steady-state integrated structure is explored. The dynamic response performances of closed-loop system against several disturbances are discussed to verify the effectiveness of control schemes for the SRC process. The simulating results show that the control structure using conventional control strategies can effectively overcome feeding disturbances in a specific range.     

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.     

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%.     

Soft-sensing modeling and intelligent optimal control strategy for distillation yield rate of atmospheric distillation oil refining process

It is a challenge to conserve energy for the large-scale petrochemical enterprises due to complex production process and energy diversification. As critical energy consumption equipment of atmospheric distillation oil refining process, the atmospheric distillation column is paid more attention to save energy. In this paper, the optimal problem of energy utilization efficiency of the atmospheric distillation column is solved by defining a new energy efficiency indicator — the distillation yield rate of unit energy consumption from the perspective of material flow and energy flow, and a soft-sensing model for this new energy efficiency indicator with respect to the multiple working conditions and intelligent optimizing control strategy are suggested for both increasing distillation yield and decreasing energy consumption in oil refining process. It is found that the energy utilization efficiency level of the atmospheric distillation column depends closely on the typical working conditions of the oil refining process, which result by changing the outlet temperature, the overhead temperature, and the bottom liquid level of the atmospheric pressure tower. The fuzzy C-means algorithm is used to classify the typical operation conditions of atmospheric distillation in oil refining process. Furthermore, the LSSVM method optimized with the improved particle swarm optimization is used to model the distillation rate of unit energy consumption. Then online optimization of oil refining process is realized by optimizing the outlet temperature, the overhead temperature with IPSO again. Simulation comparative analyses are made by empirical data to verify the effectiveness of the proposed solution.     

分批蒸馏优化策略与微机控制的研究(Ⅰ)——分批蒸馏的优化策略

本文提出了塔顶累积全回流及变压强综合回流两个分批蒸馏的新操作策略及相应的优化操作法,通过数学模拟和θ收敛计算法求出了二元(乙醇—异丙醇)和多元(正庚烷—正辛烷—正壬烷—正癸烷)物系的数值解.计算结果表明,两种新操作法分别较传统的操作法缩短生产周期30%和50%以上.     

恒全回流塔顶累积间歇精馏过程的研究

提出了一种过程始终为全回流操作的间歇精馏新型操作方式,其特征在于沿塔身不同高度设置有多个中间累积罐,操作中整塔始终处于全回流状态,每隔一段时间将下一级储罐内的液体转移至上一级储罐,塔顶储罐内液体作为产品转移到产品储槽。建立了该流程的数学模型并采用Matlab软件进行模拟,当目标产品浓度相同时,新操作方式的可以节省操作时间,在最优化的中间累计罐密集程度下,可节省50%左右,与具体操作参数相关;最后采用乙酸-水二元物系对该操作方式进行了试验验证,且整塔运行稳定易于操作控制。     

动态累积与变压强联合分批精馏过程

提出分批精馏过程中的动态累积与变压强联合操作法，并成功应用于工业高效填料塔，生产运行实验结果表明：与传统的分批精馏操作方法相比，动态累积与变压强联合操作方案不仅大幅度缩短了操作周期， 而且明显提高了分离效率， 减少了能耗， 降低操作费用， 具有显著的推广应用价值。     

Analyse und Anwendung dynamischer Optimierungsalgorithmen für Batch-Prozesse

Batch processes being increasingly used in the chemical industry. The advantages of batch processes are their flexibility, high product purity and the possibility of frequent product changeover. For the economical operation of a batch process it is necessary to develop an optimal strategy; therefore a proper optimisation approach is required. For this reason two different optimisation algorithms, differential dynamic programming and a simultaneous optimisation approach, are investigated in this paper. The characteristics of the algorithms are worked out and their efficiency is analysed. Simulation results from batch reactors and a batch column demonstrate the scope of application of the algorithms.     

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。     

分批精馏最小过渡馏分量及过渡馏分脉冲控制法的研究

研究了分批精馏最小过渡馏分量 ,在此基础上针对分批精馏过渡馏分段的特点采用了全回流 全馏出交替进行的脉冲控制法。该法以动态模拟确定了全回流时间 ,统计法确定了全馏出时间。采用正己烷 环己烷物系进行对比实验结果表明 :与传统的恒回流比操作法相比 ,脉冲操作法可明显减少过渡馏分量、缩短操作时间和提高分离效率     

工业间歇精馏DMSO不稳定因素的解决措施

对工业间歇精馏生产二甲基亚砜遇到的系统持液及蒸汽压不稳定等工艺问题,进行了分析研究,在原有的工艺设备上,采用"大回流压塔,小回流采出"的操作措施,有效地解决了二甲基亚砜生产中遇到的上述工艺问题。实验结果表明:缩短产品合格时间,提高产品品质,增加单批产品数量,取得了良好的经济效益。     

循环全回流间歇精馏控制方法的试验研究

提出了采用塔顶和塔中温度控制进行操作状态转换的循环全回流间歇精馏控制方法,并以异丙醇-正丙醇为试验物系进行了试验研究。结果表明,用塔顶和塔中温度控制动态累积全回流-全采出的状态切换是完全可行的。此外,引入塔中温度控制使产品数量、质量及操作时间优于单独用塔顶温度控制,并且双温度控制操作弹性更高。     

2，3-二氯-5-三氟甲基吡啶精馏过程的研究

采用高效θ环填料塔,通过真空精馏的方法精制提纯2,3-二氯-5-三氟甲基吡啶粗品,产品纯度达到99％以上,瞬时纯度可以达到99．3％,最高收率在75％v2上。通过对该产品的间歇蒸馏过程的研究,得到了适宜的操作条件：压力P=10kPa-30kPa,回流比R=10-30。试验证实采用变操作参数的分批精馏操作有利于提高产品的质量和收率。     

减压间歇萃取精馏分离乙酸乙酯和乙醇

通过减压间歇萃取精馏实验装置,选用N,N-二甲基甲酰胺(DMF)作为萃取剂,对乙酸乙酯和乙醇二元共沸物系的分离进行了实验研究。考察了操作参数中操作压强、回流比(体积比)、溶剂比(体积比)对分离过程的影响。实验结果表明:减小压强、提高回流比和溶剂比都能不同程度地增强分离效果,实验得出减压操作情况下的间歇萃取精馏的较佳分离条件:操作压力为10 kPa,回流比为3,溶剂比为1,产品中乙酸乙酯的质量分数为97%以上。