Theory Of Distillation Research Articles

The volatilization law of standard impurity elements in 3 N antimony during vacuum distillation and preparing antimony with 4 N8 content

A novel process for the production of high purity antimony (99.998 wt%) from crude antimony (3 N) by a two-step vacuum distillation was proposed. The process involves the volatilization of impurities (Mg, Na, Zn, As) with low boiling points, leaving antimony in the residue, followed by the retention of impurities (Fe, Si, Pb, Bi, Mn, Cu, Al, Au) with high boiling points in the residue. The feasibility of separating antimony from other impurities was analyzed using the theory of vacuum distillation, including saturation vapor pressure, molecular free path, and maximum volatilization rate. In the first step of vacuum distillation at 50 Pa and 630 ℃ for 60 min, zinc, sodium, and magnesium were volatilized to the gas phase, and their content were reduced to 0.17 ppm, 0.14 ppm, 0.13 ppm respectively, which meet the 5 N antimony standard. The content of arsenic was reduced to 1.21 ppm, while the antimony remains in the residue. In the second step of vacuum distillation at 1–10 Pa and 655 ℃ for 30 min, iron, lead, bismuth, manganese, copper, aluminum and gold were significantly reduced to 0.36 ppm, 0.35 ppm, 1.93 ppm, 0.05 ppm, 0.05 ppm, 0.12 ppm and 0.05 ppm, respectively, which meet the 5 N antimony standard, Therefore, the purity of volatile antimony obtained in the second step is 4 N8(99.998 wt%). This method provides reference for the preparation of high purity antimony.

ON THE THEORY OF EVAPORATION REFINING

The theory of sublimation and distillation refining, which takes into account the diffusion of impurities, is considered. The conceptual nature of the theory is noted due to the large number of parameters whose values are unknown.

Decomposability of linear maps under tensor powers

Both completely positive and completely copositive maps stay decomposable under tensor powers, i.e., under tensoring the linear map with itself. But are there other examples of maps with this property? We show that this is not the case: Any decomposable map, that is neither completely positive nor completely copositive, will lose decomposability eventually after taking enough tensor powers. Moreover, we establish explicit bounds to quantify when this happens. To prove these results, we use a symmetrization technique from the theory of entanglement distillation and analyze when certain symmetric maps become non-decomposable after taking tensor powers. Finally, we apply our results to construct new examples of non-decomposable positive maps and establish a connection to the positive partial transpose squared conjecture.

Minimum-reflux regime of simple distillation columns

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).

The geometry of separation boundaries: I. Basic theory and numerical support

AbstractSeparation has always been an important task in the chemical industry. Even with the recent shift in emphasis and efforts to unify the physical and biological sciences, separation will remain an important workhorse in production and product/process design. The theory of simple distillation and residue curve maps has a long history—roughly 100 years—and has made a significant impact in the way many new separation processes are synthesized and designed. The key synthesis/design concept in this approach centers on understanding the ways in which constant boiling mixtures (or azeotropes) define separation boundaries. It is now well established that these azeotropes (or eutectics in melt or fractional crystallization and other solid–liquid separations) often define curved separation boundaries that place limitations on the degree of separation that can be achieved. Despite this, there remains no clear and exact understanding of separation boundaries and no straightforward way of accurately computing them in practice. A geometric methodology is presented that shows that exact separation boundaries can be defined through the use of differential geometry and dynamical systems theory and formulated as a constrained global optimization problem. Our novel approach is based on the observation that, for ternary homogeneous liquids, separation boundaries correspond to local maxima in the line integral within a given separation region. In addition, it is shown that these local maxima in the line integral correspond to one‐sided cusps and that global optimization is absolutely necessary, given that several local maxima can exist within any separation region. Several numerical examples are presented that show that the proposed geometric approach can accurately find separation boundaries for homogeneous and heterogeneous mixtures. Finally, it is shown that our new methodology is very general and readily extends to mixtures with four or more components, reactive separations, nonequilibrium models, and other processes such as crystallization and vapor degreasing. © 2005 American Institute of Chemical Engineers AIChE J, 2006

Definition von Destillationslinien bei der Trennung von Mehrstoffgemischen

AbstractDefinition of Distillation Lines in the Separation of Multicomponent Mixtures. In recent years “distillation lines” have been used for the assessment of the separation behaviour of multicomponent mixtures, with these distillation lines being defined differently by different authors. The theory of distillation of multicomponent mixtures shows that it is appropriate to distinguish between residue lines and rectification lines. While the profile of residue lines is determined solely by the thermodynamic phase equilibrium, that of rectification lines also depends upon the mass transfer model used. By analogy with VDI Guideline 2761: “Thermal Separation Processes in Process Engineering”, it is proposed that residue lines and rectification lines are designated by the collective term distillation lines.

Geometric nonlinear analysis of multicomponent nonideal distillation: a simple computer-aided design procedure

A simple noniterative design procedure for multicomponent distillation columns is developed. The procedure is based on the geometric theory of distillation presented in our previous work, and applies to constant relative volatility, ideal, nonideal, and azeotropic mixtures. The design technique provides an accurate and efficient method for determining the number of theoretical trays in the column, the optimum feed-plate location, and the exact product distribution, without the use of lengthy iterative schemes involving column simulations, as is the current practice. The procedure is easily extended to incorporate reactive distillation columns, as well as the retrofit design of distillation columns. The design procedure is illustrated using a number of multicomponent systems, including the mixture acetic acid—water—ethyl acetate—ethanol, which exhibits three binary azeotropes, one ternary azeotrope, and a nonideal vapor phase.

Der Beitrag von H. Hausen zur Theorie der Rektifikation

AbstractContribution of H. Hausen to the theory of rectification. The theory of distillation, in particular with respect to multicomponent separation has been strongly influenced by Hausen. His major contributions in this field are presented and discussed.

Distillation at minimum variable reflux

Minimum heat input in a distillation in which the reflux is variable is calculated by a modification of U nderwood's minimum-reflux calculation. The method is based upon the analytical theory of distillation previously given by one of the authors. Instead of the molal liquid and vapour rates actually occurring in the column, generalized rates are defined which are dependent on the molal heat rates of the vapour phase and of the liquid phase. The equations between the generalized rates are formally identical with the equations between the molal rates in a distillation at constant reflux. To obtain these generalized rates the molal vapour heat content must be approximated by a linear function of the equilibrium constant of a reference component K and the molal liquid heat content must be approximated by a linear function of 1 K . These approximations need, however, only be valid in the relatively narrow temperature range between the two “pinches.” Constant relative volatilities have also to be assumed for that region only.

Teorie vyvařování alkoholu.

Teorie vyvařování alkoholu.

Reduction of multicomponent systems to binary mixtures in distillation calculations

The theory of distillation is applied to approximate a multicomponent mixture by a simpler one. In both the top section and the bottom section, two substitute components can be found which provide the best approximation of the specified components by a binary mixture for a given moderately large number of trays (e.g. 10 or 20). The distillation can then be calculated by the common methods applicable to a binary mixture. A third component is introduced if higher numbers of trays are considered but the calculation method still remains essentially that of a binary mixture. The unspecified components are taken into account by a simple correction method. Graphical methods are given to improve the latter correction and to calculate liquid or vapour rate of any actual component on an arbitrary tray. A constant ratio of volatilities is assumed.

Distillation of multicomponent mixtures

A synopsis is given of a recent theory of distillation of multicomponent mixtures in which the product of absorption factors is calculated from a summation equation. A constant ratio of volatilities is assumed. The calculation of a distillation at variable reflux can be reduced to one at constant molar reflux. The theory is applied to a distillation at constant reflux. The summation equation is solved either by successive calculation of the absorption factor product or algebraically or by graphical methods. The successive calculation is by far the quickest if only one reflux ratio is considered. The algebraic method involves the solution of two algebraic equations of higher order than two. It is shown that the multicomponent mixture may be approximated by two binary mixtures and if this is done quadratic or even linear equations have to be solved only. Even so, however, the algebraic solution takes up much time. The graphical method is also based upon the approximation by binary mixtures. It is preferred to the algebraic method on account of its quickness and it is easily surveyable. Graphs are given from which all possible columns and reflux ratio's which lead to the desired distillate and residue, can be found.

Theory of distillation and other countercurrent processes II

The theory of countercurrent processes presented in a previous article is further developed. An analytical solution of the basic equation, from which the product of absorption factors is calculated, is given. A theoretically sound procedure for reducing the distillation of a multicomponent mixture to that of two binary mixtures is developed. Algebraic as well as graphical methods can be used to perform the actual calculation. The influence of unspecified components on the absorption factor product is discussed.

Theory and Practice of Analytical Distillation

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTTheory and Practice of Analytical DistillationArthur. RoseCite this: Anal. Chem. 1950, 22, 11, 1369–1371Publication Date (Print):November 14, 1950Publication History Published online1 May 2002Published inissue 14 November 1950https://doi.org/10.1021/ac60047a006RIGHTS & PERMISSIONSArticle Views123Altmetric-Citations4LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (418 KB) Get e-Alerts Get e-Alerts

Theory of distillation and other countercurrent processes

A theory of countercurrent processes is presented which is especially applied to distillation. The product of absorption factors on the different trays is the basic function into which other variables e.g. the concentrations, can be expressed. The equation for the conservation of heat is used to calculate the product of absorption factors and it is applicable to the most general case of distillation, even if chemical reactions occur. An explicit solution is given if the volatilities of the components have a constant ratio in the top section and a (different) constant ratio in the bottom section. The reflux is variable. A graphical representation permits to obtain in one diagram a survey of all possible means by which a desired separation can be obtained. The unspecified components are approximately taken into account in this diagram. A special feature of the theory is that the number of components involved, is only of secundary importance.

The theory of molecular distillation and its experimental verification

The theory of molecular distillation and its experimental verification

Refresher Courses for Science Teachers

TERMINATION of a student's normal course of study often brings to an abrupt end his active connexion with the university. In the case of science teachers, this is particularly undesirable, for it is important that the rapid developments which are taking place in their subjects should be fully discussed between school and university teachers, especially in relation to teaching methods. With these considerations in view, a ten-day course on modern aspects of chemistry was recently held at the University College of North Wales, Bangor, in co-operation with the Welsh Department of the Board of Education, one of the inspectors of which, Dr. D. M. Williams, assisted in the organisation of the course. Summaries were given of recent work on atomic structure, valency theory and its application to problems concerning the structure and reactions of some inorganic and organic compounds, the electro-chemistry of solutions, and the chemistry of natural and synthetic products of special interest ; lectures and experiments were included illustrating advances in the theory and practice of pH determination, indicators, electrometric titrations, distillation, and chromatography, together with a demonstration of glass-blowing technique, a show of scientific films and a display of modern books, dealing especially with the subjects selected. While it was apparent that the teachers attending the course derived benefit and interest from it, the discussions proved most stimulating also to the University personnel who participated. The course was conducted by Prof. E. D. Hughes and Drs. W. R. Angus, I. Dostrovsky, J. Graham and D. R. Llewellyn, assisted in the experimental work by Dr. F. Brown, Mr. T. R. Jacobs, and senior research students ; Prof. C. W. Davies and Dr. W. C. Evans, of University College, Aberystwyth, gave special lectures.

A new general equation for the liquid-vapour relations of binary systems. Part II. Application to the theory of practical distillation

A new general equation for the liquid-vapour relations of binary systems. Part II. Application to the theory of practical distillation

Distillation

THE book under notice contains a mathematical account of the theory of distillation, the theory of fractionating columns, and a discussion of the apparatus and methods involved in distillation, both laboratory and industrial. The section on low-pressure distillation is of particular interest, since some modern industrial processes, such as the purification of vitamins, depend upon this process. The separation of liquids by the principle of azeotropie mixtures is dealt with fairly fully, especially as it concerns the dehydration of alcohol, which is becoming important with the use of 99-100 per cent alcohol for motor fuel.

The Theory of Fractional Distillation.

ADVERTISEMENT RETURN TO ISSUEPREVArticleNEXTThe Theory of Fractional Distillation.Warren K. LewisCite this: Ind. Eng. Chem. 1909, 1, 8, 522–533Publication Date (Print):August 1, 1909Publication History Published online1 May 2002Published inissue 1 August 1909https://doi.org/10.1021/ie50008a008RIGHTS & PERMISSIONSArticle Views1078Altmetric-Citations11LEARN ABOUT THESE METRICSArticle Views are the COUNTER-compliant sum of full text article downloads since November 2008 (both PDF and HTML) across all institutions and individuals. These metrics are regularly updated to reflect usage leading up to the last few days.Citations are the number of other articles citing this article, calculated by Crossref and updated daily. Find more information about Crossref citation counts.The Altmetric Attention Score is a quantitative measure of the attention that a research article has received online. Clicking on the donut icon will load a page at altmetric.com with additional details about the score and the social media presence for the given article. Find more information on the Altmetric Attention Score and how the score is calculated. Share Add toView InAdd Full Text with ReferenceAdd Description ExportRISCitationCitation and abstractCitation and referencesMore Options Share onFacebookTwitterWechatLinked InReddit PDF (1 MB) Get e-Alerts