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间歇精馏循环全回流操作是一种具有前景的新型操作方式。文中在循环全回流操作的基础上,首次提出了无累积罐循环全回流新操作方式。通过数学模型对其进行模拟,模拟计算比较了新方式、恒回流比间歇操作和塔顶储罐一次全回流操作3种操作方式。模拟结果表明:无累积罐新操作方式的全回流阶段时间由2个因素决定,全回流开始时精馏塔内的浓度梯度情况和精馏塔内持液的平均浓度。随着全回流-全采出操作的进行,后续循环中的全回流阶段的时间增加,全采出阶段时间减少。当进料浓度低时,新操作方式的分离效率比恒回流比方式高26.4%—30.1%,并通过模拟揭示了新操作方式的特点。研究表明:无累积罐循环全回流操作方式是一种新型高效的分离操作。 相似文献
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鉴于间歇精馏热力学效率低的缺点,提出带有内部热集成的多储罐间歇精馏全回流操作(IHIMVBD)分离二元混合物的新型操作方式。在该操作中,多储罐间歇精馏塔被同轴的夹套式再沸器环绕,利用安装在再沸蒸汽管线上的压缩机使精馏塔的操作压力高于夹套式再沸器,使热量通过精馏塔壁面从高压的精馏塔传向低压的再沸器,实现热量的内部集成。为了进一步提高热力学效率和经济效益,将塔顶蒸汽再压缩技术应用于IHIMVBD,构成强化的内部热集成多储罐间歇精馏全回流操作(Int-IHIMVBD)。该操作能额外利用被压缩的塔顶蒸汽的潜热供给塔釜料液再沸,实现塔顶蒸汽与塔釜料液的热集成。通过模拟分离乙醇-正丙醇的实例表明,相比MVBD和IHIMVBD,Int-IHIMVBD能显著提高分离过程的热力学效率和经济效益。 相似文献
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多储罐动态全回流分离方法 总被引:1,自引:1,他引:0
多储罐间歇精馏是新型操作方式,目前仅用于多组分混合物分离.为了扩大多储罐间歇精馏塔的应用,将其用于2组分物系的分离,提出了多储罐动态全回流分离方法.其特点是可分为全回流提浓和倒罐采出阶段,这2个阶段交替进行,直到分离结束.建立了该过程的数学模型,并与常规恒回流比方式比较,结果表明:动态全回流方法省时.进一步通过乙酸-水... 相似文献
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Cyclic total reflux batch distillation with two reflux drums 总被引:1,自引:0,他引:1
The present work proposes a novel cyclic total reflux (CTR) operation of batch distillation with two reflux drums working alternatively. A mathematical model is set up for the process. The computational comparison of the novel policy with the regular constant reflux and non-cyclic total reflux (NCTR) operations is also presented. The experimental runs of the new mode show that it can be operated and controlled more easily. The novel operation is significantly time saving compared to the mode of regular constant reflux theoretically and experimentally. The two reflux drum mode of CTR is also suitable for the separation of the mixture containing a large amount of light component. 相似文献
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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。 相似文献
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Vladimir N. Maleta Olesja Bedryk Alexander Shevchenko Anton A. Kiss 《American Institute of Chemical Engineers》2019,65(9):e16673
Cyclic distillation is a proven process intensification method for enhanced separation of various mixtures. It uses an alternative operating mode based on separate phase movement which leads to important practical advantages (vs conventional mode) such as increased column throughput, lower equipment cost (using much less trays at the same reflux ratio) and reduced energy requirements by 20–35% (smaller reflux ratio at the same number of stages), and better separation performance (up to three times). However, if the impurities to be separated are in very low amounts in the feed then distillation is not favorable from an energy use viewpoint. This article is the first to report the practical performance of a continuous process for ethanol purification by air stripping using a cyclic mode of operation, a novel process that avoids the costs of distillation. The purification of ethanol food grade (96.4 vol%) from volatile impurities (0.5 vol%) such as esters, aldehydes, and alcohols, is carried out in a hydro-selective column with five stages. The lightweight impurities are removed from a stream that is the head fraction of a distillation column. This is usually a waste stream amounting to 3–6% of the plant production rate. By concentrating the stream with impurities, more ethanol is produced such that the losses are reduced to only 1–1.5% of the plant capacity. Based on the experimental results presented in this work, a process consisting of two air stripping columns using cyclic operation is proposed for industrial implementation. 相似文献
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V. Yu. Aristovich Yu. V. Aristovich A. Yu. Sokolov J. W. Fulmer Chandrasekhar Krishnan M. V. Ramani Prashant Tatake 《Chemical Engineering Communications》2004,191(6):844-859
The conventional rectification method to separate and purify chemical mixtures has the disadvantage of being an energy-intensive unit operation. The innovative method proposed in this article employs vapor and liquid recycles to the trays that in turn reduce the reflux rate and vapor boil-up rate, resulting in energy reduction without compromising the separations.
These findings were supported with examples of ethanol-water and butane- pentane system separations. With ethanol-water system, the experiments were conducted without overhead liquid recycle and using 16 and 5 vapor recycles. The energy saved was found to be 25-35% for 16 recycles and 20-30% for 5 recycles. Butane-pentane system was chosen as an example of industrial use of the proposed method. A liquid overhead reflux ratio of 0.5 (L/D) was used with vapor recycles, compared to a reflux ratio of 1.25 for the conventional separation without vapor recycles. This resulted in 30-35% saving in energy while giving the same productivity of the column. Butane-pentane separation was also simulated using a commercial process simulator (ASPEN©PLUS). 相似文献
These findings were supported with examples of ethanol-water and butane- pentane system separations. With ethanol-water system, the experiments were conducted without overhead liquid recycle and using 16 and 5 vapor recycles. The energy saved was found to be 25-35% for 16 recycles and 20-30% for 5 recycles. Butane-pentane system was chosen as an example of industrial use of the proposed method. A liquid overhead reflux ratio of 0.5 (L/D) was used with vapor recycles, compared to a reflux ratio of 1.25 for the conventional separation without vapor recycles. This resulted in 30-35% saving in energy while giving the same productivity of the column. Butane-pentane separation was also simulated using a commercial process simulator (ASPEN©PLUS). 相似文献
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V. YU. ARISTOVICH YU. V. ARISTOVICH A. YU. SOKOLOV J. W. FULMER CHANDRASEKHAR KRISHNAN M. V. RAMANI 《Chemical Engineering Communications》2013,200(6):844-859
The conventional rectification method to separate and purify chemical mixtures has the disadvantage of being an energy-intensive unit operation. The innovative method proposed in this article employs vapor and liquid recycles to the trays that in turn reduce the reflux rate and vapor boil-up rate, resulting in energy reduction without compromising the separations. These findings were supported with examples of ethanol-water and butane- pentane system separations. With ethanol-water system, the experiments were conducted without overhead liquid recycle and using 16 and 5 vapor recycles. The energy saved was found to be 25–35% for 16 recycles and 20–30% for 5 recycles. Butane-pentane system was chosen as an example of industrial use of the proposed method. A liquid overhead reflux ratio of 0.5 (L/D) was used with vapor recycles, compared to a reflux ratio of 1.25 for the conventional separation without vapor recycles. This resulted in 30–35% saving in energy while giving the same productivity of the column. Butane-pentane separation was also simulated using a commercial process simulator (ASPEN©PLUS). 相似文献
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模拟移动床(SMB)是混合二甲苯分离的重要技术。模拟移动床区域回流比是决定产品质量的关键参数。在真实移动床(TMB)建模方法基础上,结合实际工况数据,建立了模拟移动床吸附分离过程机理模型,并通过分析区域回流比对产品质量的影响,得到不同产品质量要求以及进料品质的情况下区域回流比的操作区间。仿真结果表明,TMB建模方法能较好地描述模拟移动床实际工况。基于机理模型对操作区间的分析结果可以为模拟移动床分离过程的工艺设计和操作提供指导意见。 相似文献
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R. Yu. Danilov F. B. Petlyuk L. A. Serafimov 《Theoretical Foundations of Chemical Engineering》2007,41(4):371-383
A general algorithm for calculating minimum reflux ratios in simple distillation columns used for the separation of ideal and nonideal (including azeotropic) homogeneous multicomponent mixtures is proposed. The algorithm deals with various splits: direct, indirect, intermediate, and with one distributed component. The algorithm is mathematically rigorous, developed on the basis of the geometrical theory of distillation, and makes it possible to consider the special features of nonideal mixtures (tangent pinch, necessity of using nonadiabatic columns). 相似文献
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Separation of gas mixtures by adsorption . Gas mixtures are separated primarily by absorption and rectification. Rectification requires at least (v + 1)-fold of the enthalpy of the distillate as heat energy (v is the reflux ratio). In the case of absorption, the resulting solution is frequently subjected to thermal regeneration with the energy requirement depending inter alia on the boiling point of the solvent. In view of the high energy requirements of these processes and the development of new adsorbents, possibilities of separating by adsorption with subsequent regeneration of the adsorbents, above all by change in pressure, are investigated. The separation of gas mixtures in adsorber beds (e.g. molecular sieves, silica gel, activated charcoal and coke, or alumina) depend upon various separating effects: steric effects, equilibrium effects, kinetic effects. A survey is given of proposed and practical industrial separation processes utilizing adsorption. 相似文献
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苯乙酮与α-苯乙醇属近沸点物系,用普通精馏方法很难将二者进行有效地分离。在对已报道的分离方法进行比较分析的基础上,提出了采用萃取精馏方法来分离苯乙酮和α-苯乙醇。文中首先通过定性判断和基团贡献法定量地估算选择了该二元物系合适的萃取剂为丙三醇。然后采用Aspen Plus化工模拟软件中的RadFrac模块进行了萃取精馏塔的模拟,分别考察了溶剂与原料进料位置、回流比、溶剂比对分离效果的影响。结果表明:对于处理量为1 000 kg/h的待分离物系,操作压力为5 kPa,在塔板数为30的条件下萃取精馏塔在原料进料位置为第19块塔板,溶剂进料位置为第6块塔板,回流比为3∶1(质量比),溶剂流率为800 kg/h的优化条件下,可以使塔顶苯乙酮质量分数达到99.8%,且塔釜几乎不含苯乙酮。模拟结果对进一步的实验研究和工业生产具有一定的指导意义。 相似文献
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Distillation columns with multiple feeds are often used in processes for the separation of multicomponent mixtures. The minimum energy demand of such columns is determined via the minimum reflux and reboil, respectively. A novel method for directly calculating the minimum reflux ratio is presented in this paper. Applicable to ideal, nonideal and azeotropic mixtures the method is based merely on the knowledge of vapor-liquid equilibrium of the feed mixtures. This knowledge allows the determination of the internal concentration profile near the feed entry and, in turn, the calculation of both minimum reflux and optimal sequence of feeds. This sequence of feeds depends on feed compositions and product compositions, as well. Surprisingly, sometimes a multiple feed entry requires a higher energy demand than premixing the feed streams. 相似文献