McCabe-Thiele Diagram Research Articles

Rigorous Computation of Binary Distillation Systems

Abstract A computation algorithm for the distillation of binary systems based on the concepts involved in the graphical Ponchon—Savarit method is introduced. Equilibrium and enthalpy data are estimated by the UNIQUAC activity coefficient equation. All the parameters of the system (temperatures, enthalpies, flow rates, and composition of the streams in each stage) are computed with much higher accuracies than those obtained by the graphical method.

Membrane cascades for the separation of binary mixtures

For the separation of binary mixtures several techniques can be considered, of which distillation is the most widely used. When problems occur in distillation (like the formation of an azeotropic mixture), membrane separation can be an alternative. A cascade of membranes has to be applied in those cases where it is impossible to achieve a complete separation in a single-membrane separation process. To calculate the separation in such a cascade, a McCabe—Thiele diagram is used in which the equilibrium curve is determined by the membrane selectivity. Optimization calculation for the cascade have been performed with respect to the total membrane surface area. Because of the large reflux flows around the feed stage, the permeate—retentate ratio in the feed stage has to be chosen carefully, since the required membrane surface area is determined merely by the permeate flows. The membrane characteristics that determine the required membrane surface area are selectivity and permeability: an increased selectivity or permeability reduces the membrane area. However, an increase of the selectivity usually goes with a decrease of the permeability. It appears from this study, that for selectivity and permeability values commonly found for reverse-osmosis (RO) membranes, an increase of the permeability affects the required membrane area to a larger extent than an increase in selectivity. This effect is illustrated by simulations for RO membranes used for the separation of water—1,3-butanediol mixtures. The total membrane area can be reduced by 25% when two membranes area available with opposite selectivity, i.e. membranes with a retention for the other component.

Computer-aided graphics in distillation columns design

A portable computer simulator has been developed to aid in the design of distillation columns with either an internal reboiler or an open steam. The program (PANCHN) uses the traditional Ponchon-Savarit method and a modified form which incorporates a more exact analysis of the feed region in the case of a partially vaporized feed. Examples of this simulation program and its computer graphics output are presented to illustrate the program's capability and usefulness in studying the effect of operating parameters in the design of distillation columns. While equilibrium data for some systems are stored in its data bank, the present simulator has the flexibility of reading equilibrium data for other systems, as well as overriding stored data.

Solvent extraction for metal recovery incorporating organic and aqueous phase bypass

Solvent extraction plants are operated using a simple closed-loop flow for the organic phase and simple flow of aqueous phase through contactors. This paper examines the use of “by-pass” of either aqueous or organic phases by means of a McCabe-Thiele diagram. The process is considered for organic-phase bypass between extraction and stripping sections of a mixer settler plant and for aqueous bypass in a centre fed contactor of the type used in nuclear fuel reprocessing. The advantages of the use of “bypass” are considered.

DISTILLATION COLUMN DESIGN BY METHOD OF McCABE AND THIELE: DISTMAN COMPUTER GRAPHICS PROGRAM

A computer graphics program developed for the IBM PC calculates equilibrium and operating lines and steps off the number of stages on screen using the McCabe-Thiele method. The results are obtained by graphics, not by numerical methods, so that the accuracy depends upon the screen resolution or pixel density. The equilibrium line is drawn from bubble-point temperature calculations using constants from the Wilson and Antoine equations. The operating lines and staircase are constructed by computer graphics according to the prescribed operating parameters. Design variables, which include the reflux ratio, quality of feed, Murphree efficiency, product purities and pressure, may be changed interactively.

Experimental study of a simulated counter-current adsorption system—IV. Non-isothermal operation

In an isothermal continuous counter-current adsorption separation process the product streams are generally diluted relative to the feed. However, this limitation does not apply to a non-isothermal system and it is shown that by applying a properly controlled temperature profile one may obtain the more strongly adsorbed species at a concentration substantially greater than the feed concentration. The practical feasibility of such a system is demonstrated experimentally for the separation of fructose-glucose mixtures. Under properly selected non-isothermal conditions an extract product containing 42% wt fructose (+2% glucose) was obtained from a feed mixture containing 24% of both fructose and glucose. The operation of the system and the proper choice of conditions can be understood by considering the McCabe-Thiele operating diagram.

An experimental study of a simulated counter-current adsorption system—I. Isothermal steady state operation

Results of an experimental study of a simulated counter-current adsorption system for separation of glucose-fructose mixtures are presented. Efficient separation may be achieved under a wide range of conditions. It is shown that the behaviour of the system, under steady state conditions, may be well described in terms of an equivalent counter-current flow system. Concentration profiles calculated from the dispersed plug flow model, with the dispersion coefficient calculated from pulse chromatographic measurements, provide a good representation of the experimental profiles. Alternatively the behaviour may be described in terms of the equilibrium stage model and the McCabe-Thiele diagram provides a useful means of visualizing the effects of changes in process conditions. The chromatographic HETP is about 10 cm and is approximately the same for both glucose and fructose and independent of fluid velocity, suggesting that axial mixing is more important than mass transfer resistance.

Comments on "Analytical form of the Ponchon-Savarit method for systems with straight enthalpy-composition phase lines"

Comments on "Analytical form of the Ponchon-Savarit method for systems with straight enthalpy-composition phase lines"

Response to comments on "Analytical form of the Ponchon-Savarit method for systems with straight enthalpy-composition phase lines

Response to comments on "Analytical form of the Ponchon-Savarit method for systems with straight enthalpy-composition phase lines

Numerical Analysis of Hydrogen Isotope Separation Characteristics in Improved Dual Temperature Exchange Reaction System between Water and Hydrogen Gas

A dual temperature hydrogen isotopic exchange reaction system between water and hydrogen gas is numerically analyzed. The system has two features; high efficiency of isotope exchange reaction and operation under atmospheric pressure. To achieve them, the low temperature section of the system is composed of water mist and hydrogen gas co-current reactor units. For the high temperature section, a multistage-type reactor, in which a bubble plate, superheater and catalyst bed are alternatively arranged, is applied. From a material balance between these reactors, enrichment and decontamination factors for the system are expressed as functions of seven parameters: unit number of the low temperature co-current reactor (X); stage number of the high temperature section (Y); flow ratio of tritium enriched water to decontaminated water (P/W), flow ratio of feed water to hydrogen gas (F/G); reaction temperatures of the low and high temperature sections (T c , T h ); and bubble plate temperature (T b ). Numerical calculations show that enrichment factor depends remarkably on F/G and T b as well as X and Y. In order to understand the separation characteristics visually, the McCabe-Thiele diagrams for the present system are drawn and compared with the results calculated.

Membrane rectification columns for gas separation and determination of the operating lines using the mccabe—thiele diagram

A new continuously operating separating unit — a membrane rectification column — has been developed for the separation of gases by membranes. The membrane rectification column can be characterized as a “step-by-step separating process”. In this article the equations for the operating lines have been constructed to show the separating process with the new enrichment technique in the McCabe—Thiele diagram.

New process developments in gas separation with membranes

We have summarized the potential for theoretical calculation for membrane rectification columns as plate columns, and the devices and optimization possibilities resulting from this. For a fundamentally new type of processing method for gas separation processing with membranes — a continuous procedure — a calculation process was developed into plant dimensioning. In addition, a graphical method for defining the number of theoretical plates was presented in the McCabe—Thiele diagram. The comparison of the concentration profiles yielded an optimization criterion for interconnection of various plant types.

Analytical form of the Ponchon-Savarit method for systems with straight enthalpy-composition phase lines

Analytical form of the Ponchon-Savarit method for systems with straight enthalpy-composition phase lines

A New Method for the Hydrogen Isotope Exchange Reaction in a Hydrophobic Catalyst Bed

To improve the isotope exchange reaction efficiency between water and hydrogen, a new reactor in which water mists and hydrogen gas react cocurrently was studied. To apply this to the enrichment of tritium in heavy water, a dual temperature isotope exchange reactor which is composed of cocurrent low temperature reactors and the usual countercurrent high temperature reactor was proposed and analyzed using a McCabe-Thiele diagram. By utilizing cocurrent reactors, in combination, the necessary catalyst volume can be reduced to one-tenth as compared with the usual countercurrent low temperature reactor.

Continuous thermal diffusion—the analogy to distillation

The classical equation which describes the effects of the variables is based on a simplifying assumption which limits the variation of concentration. That assumption is here removed to give a more realistic description of concentration throughout the column. This leads to a correction term in the classical equation which can be large, but in correlating experimental data makes a difference smaller than errors caused by the measurements. Thus the improved solution if of consequence in correlating data. However, the more realistic description of concentration allows an analogy to distillation to be developed which can be extended to a McCabe—Thiele diagram, with an unusual definition of an “equilibrium” line. The result is that the library of concepts, rules of thumb, design methods, and effects of the variables may be transferred from distillation to thermal diffusion. The sole exception appears to be that the value of HETP for a thermal column can cover a much wider range of values.

Communication. McCabe-Thiele Diagram for Feed Which Is Partly Vapor

Communication. McCabe-Thiele Diagram for Feed Which Is Partly Vapor

Modification of McCabe-Thiele Method for Systems of Unequal Heats of Vaporization

Modification of McCabe-Thiele Method for Systems of Unequal Heats of Vaporization

McCabe-Thiele Diagram for the Ideal Cascade

A McCabe-Thiele diagram is constructed for the ideal cascade used in the theory of isotopic separations by distillation, considering only the enriching section. The treatment shows that the ideal cascade requires twice the mim-mum number of stages for any separation and twice the minimum downflow at all interstage points. (D.L.C.)