共查询到20条相似文献,搜索用时 31 毫秒
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夹紧区是精馏塔内出现的浓度几乎不变的区域,对于三元物系来说,根据夹紧区在塔内出现的位置可分为:上、中和下加紧区.在无穷板数和任一瞬时釜浓下选择不同的回流比可使分批精馏处于不同夹紧区下操作.文中讨论了三元恒回流比分批精馏过程中夹紧区的演变,在Rayleigh方程的基础上建立了应用夹紧区原理确定多元恒回流比分批精馏最小回流比的方法.该方法并不要求相对挥发度为常数,并且能准确计算顶浓,克服了通常所采用的Underwood公式法的缺陷,为多元分批精馏的简捷设计奠定了基础. 相似文献
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A systematic procedure for synthesis of intensified nonsharp distillation systems with fewer columns
Nonsharp separation sequences can intrinsically improve thermodynamic efficiency than that of sharp sequences for a multicomponent distillation. There are much more nonsharp sequences than that of sharp sequences. In this paper, the synthesis of new intensified distillation systems from nonsharp separation sequences is presented. Such intensified distillation systems have fewer columns and have the potential to reduce both energy and capital costs than conventional configurations. First, the representation of any nonsharp sequence with the simple column configuration is found to be the necessary starting point. Then, five strategies are introduced which present different mechanisms to change the structures of the distillation configurations. Third, a systematic procedure is formulated which can achieve the intensified distillation systems with fewer columns systematically. Finally, the systematic method has been applied to different examples of nonsharp separation sequences. It is demonstrated that the method can be used to generate the new intensified distillation systems from any nonsharp separation sequences. The method is easy to use and can explicitly derive all of the intensified distillation systems for the nonsharp separation sequences for a multicomponent distillation. 相似文献
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Global optimization of multicomponent distillation configurations: 2. Enumeration based global minimization algorithm 下载免费PDF全文
Ulaganathan Nallasivam Vishesh H. Shah Anirudh A. Shenvi Joshua Huff Mohit Tawarmalani Rakesh Agrawal 《American Institute of Chemical Engineers》2016,62(6):2071-2086
We present a general Global Minimization Algorithm (GMA) to identify basic or thermally coupled distillation configurations that require the least vapor duty under minimum reflux conditions for separating any ideal or near‐ideal multicomponent mixture into a desired number of product streams. In this algorithm, global optimality is guaranteed by modeling the system using Underwood equations and reformulating the resulting constraints to bilinear inequalities. The speed of convergence to the globally optimal solution is increased by using appropriate feasibility and optimality based variable‐range reduction techniques and by developing valid inequalities. The GMA can be coupled with already developed techniques that enumerate basic and thermally coupled distillation configurations, to provide for the first time, a global optimization based rank‐list of distillation configurations. © 2016 American Institute of Chemical Engineers AIChE J, 62: 2071–2086, 2016 相似文献
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This paper presents a new formulation of the infinite plate or minimum reflux limit of a multicomponent distillation column. Based on this model, two new calculation methods are developed. The first is a short-cut method which extends Underwood's classic minimum reflux treatment to variable molar overflow situations. The second is a rigorous method which is similar to a multicomponent flash calculation and represents a significant computational advance over other rigorous methods. 相似文献
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Amnart JantharasukRafiqul Gani Andrzej GórakSuttichai Assabumrungrat 《Chemical Engineering Research and Design》2011,89(8):1295-1307
A new methodology for design and analysis of reactive distillation has been developed. In this work, the element-based approach, coupled with a driving force diagram, has been extended and applied to the design of a reactive distillation column involving multielement (multicomponent) systems. The transformation of ordinary systems to element-based ones and the aggregation of non-key elements allow the important design parameters, such as the number of stages, feed stage and minimum reflux ratio, to be determined by using simple diagrams similar to those regularly employed for non-reactive systems consisting of two components. Based on this methodology, an optimal design configuration is identified using the equivalent binary-element-driving force diagram. Two case studies of methyl acetate (MeOAc) synthesis and methyl-tert-butyl ether (MTBE) synthesis have been considered to demonstrate the successful applications of the methodology. Moreover, energy requirements for various column configurations corresponding to different feed locations are determined to verify whether the optimal design can be identified by following the proposed methodology. 相似文献
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In this work, a dynamic model was developed to simulate the transient behaviour of a pilot scale, continuous, siagewise, 15 plate distillation column separating a mixture of ethanol, iso-propanol and isobutanol. The accuracy of the predictions was assessed by transient response data collected during experiments under step changes in reflux ratio, feed flow rate and feed composition.
Results demonstrated the feasibility of simulating multicomponent distillation under unsteady state conditions with fairly good success. Further improvements were suggested for a better accuracy 相似文献
Results demonstrated the feasibility of simulating multicomponent distillation under unsteady state conditions with fairly good success. Further improvements were suggested for a better accuracy 相似文献
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蒸馏塔分散PID控制器整定研究 总被引:4,自引:4,他引:0
结合一种双输入双输出 (TITO)分散PID控制器的设计方法 ,并将其应用于乙醇—水的蒸馏分离过程控制中。该法根据相应的收敛性算法 ,通过一系列继电闭环实验辨识预期临界点 (DCP) ,利用T L整定公式获取分散PID控制器参数。通过仿真对比试验 ,表明所设计的控制系统具有满意的动态性能 相似文献
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Zheyu Jiang Zewei Chen Joshua Huff Anirudh A. Shenvi Mohit Tawarmalani Rakesh Agrawal 《American Institute of Chemical Engineers》2019,65(11):e16737
The operating cost of a multicomponent distillation system comprises two major aspects: the overall heat duty requirement and the temperature levels at which the heat duties are generated and rejected. The second aspect, often measured by the thermodynamic efficiency of the distillation system, can be quantified by its total exergy loss. In this article, we introduce a global optimization framework for determining the minimum total exergy loss required to distill any ideal or near-ideal multicomponent mixture using a sequence of columns. Desired configurations identified by this new framework tend to use milder-temperature reboilers and condensers and are thus attractive for applications such as heat pump assisted distillation. Through a case study of shale gas separations, we demonstrate the effectiveness of this framework and present various useful physical insights for designing energy efficient distillation systems. 相似文献
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A systematic method to synthesize all dividing wall columns for n‐component separation—Part I 下载免费PDF全文
Gautham Madenoor Ramapriya Mohit Tawarmalani Rakesh Agrawal 《American Institute of Chemical Engineers》2018,64(2):649-659
We present an easy‐to‐use step‐wise procedure to synthesize an initial‐dividing wall column (i‐DWC) from any given n‐component basic distillation column sequence or its thermally coupled derivative. The procedure to be used is dependent on the nature of the distillation column sequence that is to be converted into a DWC, and comprises of an intuitive set of steps that we demonstrate through examples. It is noteworthy that, even for a ternary distillation, 15 potentially useful DWCs, some of which had been missing from the literature, have now been identified. This work significantly expands the search space of useful DWCs to separate any given multicomponent mixture. © 2017 American Institute of Chemical Engineers AIChE J, 64: 649–659, 2018 相似文献
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A side distillation column is widely used to separate multicomponent mixtures into three products. However, this kind of column consumes considerable amounts of energy due to thermodynamic restrictions and the nature of the distillation process. Retrofit of the side distillation column to a dividing wall column (DWC) can result in significant energy savings. This study evaluated a systematic method for optimal retrofit of a side stream column to a DWC. The minimum energy requirement for the separation of a multicomponent mixture was used for a feasibility study. Subsequently, design and optimization was performed using shortcut, rigorous and response surface methodology. One case study was illustrated to demonstrate the proposed methodology. The results showed that the optimal retrofit of a side distillation column to the DWC could not only save a significant amount of energy, but also increase the capacity. This study highlights the potential for retrofitting a side stream column to a DWC from a techno economic point of view. 相似文献
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提出了以有效能消耗最小为目标的复杂精馏塔优化设计新方法。给出了精馏塔优化设计模型及最佳进料位置、适宜理论板数NT、塔内换热器简约的确定方法,并以两组分正庚烷和乙苯的混合物为例进行设计与讨论。优化后的精馏塔含有中间换热器,与传统的简单塔有本质的区别,平衡线和操作线均处于相对平均的位置,更节能。 相似文献
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精馏塔是化工过程经常用到的一种分离设备,操作条件不当,易使精馏塔进入异常工况.正常工况时,出料温度随回流量增大而降低,模型增益为负;回流量继续增大,导致板效率下降,出料温度开始上升,模型增益变为正,精馏塔进入异常工况.针对此情况提出一种基于最小二乘法的乙烯精馏塔模型增益在线辨识方法,在线实时辨识出模型增益符号,根据辨识结果,判断乙烯精馏塔是否进入异常工况.建立正常与异常工况的乙烯精馏塔控制系统,根据模型增益辨识结果,由负反馈原理确定正常与异常工况中控制器正反作用,使得回流量和出料温度均控制在正常工况允许范围内,保证乙烯精馏塔在正常工况工作,实现乙烯精馏塔正常与异常工况控制. 相似文献
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提出了以有效能损耗最小为目标、同时又考虑热集成的多组分复杂精馏塔序列优化设计新策略。该复杂精馏塔模型:1股进料、2股出料,每块理论板上均可有中间冷凝器或再沸器。复杂精馏过程的设计步骤是:①根据过程有效能最小确定优化塔序列;②对每个塔优化设计出含中间换热器的复杂塔;③考虑多效且允许热集成的复杂精馏流程,以塔压为决策变量,以精馏过程有效能损耗最小为目标,建立并优化设计出一个热集成的复杂精馏流程。一个3组分精馏过程的例子表明所提策略简单有效,可用来指导多组分精馏过程的优化设计。 相似文献
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一种改进的多元精馏塔动态模型 总被引:3,自引:0,他引:3
综合了精馏塔的物料及能量平衡、塔板水力学方程、塔板效率及再沸器动态特性,给出一种改进的非理想多元物系精馏塔通用动态数学模型.增加了汽液平衡计算,从而弥补了文献[1]所提出的动态模型的缺陷,提高了其精度和通用性.模型仿真算法采用Gear积分方法,稳定性好,对解刚性比很高的精馏塔微分方程组十分有效.通过对某丙烯腈萃取精馏塔的仿真表明,该动态模型能够较好地反映对象的动态形为. 相似文献
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研究了乙醇脱水塔内的两相共沸精馏和汽液液三相共沸精馏过程。利用Aspen plus模拟软件对乙醇脱水塔内4种工况的精馏曲线、共沸剂浓度分布、回流量和再沸器能耗进行了分析比较。结果表明,苯做共沸剂时,脱水塔内两相共沸精馏和汽液液三相共沸精馏的精馏曲线、共沸剂浓度分布、回流量和再沸器能耗相近,脱水塔精馏曲线都跨越了精馏边界,并且共沸剂在塔内大多数板上都有较高浓度分布。而环己烷做共沸剂时,两相共沸精馏工况和汽液液三相共沸精馏工况条件下的脱水塔内精馏曲线、共沸剂浓度分布、回流量和再沸器能耗有较大差别。汽液液三相共沸精馏工况条件下,环己烷在塔内大多数板上有较高浓度分布,起到较好的脱水作用,而两相共沸精馏工况条件下脱水塔内共沸剂仅分布在塔顶几块塔板上,塔内多数板上没有起到共沸剂作用。 相似文献
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