The Fenske equation in fractional distillation is an equation for calculating the minimum number of theoretical plates required for separation of a binary feed stream by a fractionation column operated at total reflux (i.e., no product distillate is withdrawn from the column). Fractional distillation is the separation of a mixture into its component parts, or fractions, such as in separating chemical compounds by their boiling point by heating them to a temperature at which several fractions of the compound will evaporate. ... An equation is a mathematical statement, in symbols, that two things are the same. ... A theoretical plate in separation processes is a hypothetical zone in which two phases establish an equilibrium, also referred to as an equilibrium stage or a theoretical tray. ... A fractionating column is an essential item used in the distillation of liquid mixtures so as to separate the mixture into its component parts, or fractions, based on the differences in their volatilities. ... Diagram of typical reflux apparatus. ...

The equation was derived by Merrell Fenske in 1932 ^[1], who served as the head of the chemical engineering department at the Pennsylvania State University from 1959 to 1969. Chemical engineering is the branch of engineering that deals with the application of physical science, e. ... The Pennsylvania State University (commonly known as Penn State) is a state-related, land-grant university. ...

Diagram of fractionating column operating on total reflux

This is one of the many forms of the Fenske equation:^[2][3][4][5] Image File history File links No higher resolution available. ...

For ease of expression, the more volatile and the less volatile components are commonly referred to as the light key (LK) and the heavy key (HK), respectively. The mole fraction is one way of expressing the relative concentration of a given species. ...

If the relative volatility of the light key to the heavy key is constant from the column top to the column bottom, then α_avg. is simply α. If the relative volatility is not constant from top to bottom of the column, then the following approximation may be used:^[2]

The above Fenske equation can be modified for use in the total reflux distillation of multi-component feeds.^[3]

Another form of the Fenske equation

A derivation of another form of the Fenske equation for use in gas chromatography is available on the U.S. Naval Academy's web site.^[6] Using Raoult's law and Dalton's Law for a series of condensation and evaporation cycles (i.e., equilibrium stages), the following form of the Fenske equation is obtained: Teamwork: Fourth Class Midshipmen lock arms and use ropes made from uniform items as they brace themselves climbing the Herndon Monument The United States Naval Academy, or USNA, is an institution for the undergraduate education of officers of the United States Navy and the United States Marine Corps. ... In chemistry, Raoults law states that the vapor pressure of mixed liquids is dependent on the vapor pressures of the individual liquids and the molar vulgar fraction of each present in solution. ... In chemistry and physics, Daltons law (also called Daltons law of partial pressures) states that the total pressure exerted by a gaseous mixture is equal to the sum of the partial pressures of each individual component in a gas mixture. ... A theoretical plate in separation processes is a hypothetical zone in which two phases establish an equilibrium, also referred to as an equilibrium stage or a theoretical tray. ...

In chemistry and physics, Vapor pressure is the pressure of a vapor in equilibrium with its non-vapor phases. ...

See also

• Continuous distillation
• Distillation
• Fractional distillation
• Fractionating column
• McCabe-Thiele method

Continuous distillation is a distillation process, which does not require interruption for adding raw material. ... Laboratory distillation set-up using, without a fractionating column 1: Heat source 2: Still pot 3: Still head 4: Thermometer/Boiling point temperature 5: Condenser 6: Cooling water in 7: Cooling water out 8: Distillate/receiving flask 9: Vacuum/gas inlet 10: Still receiver 11: Heat control 12: Stirrer speed... Fractional distillation is the separation of a mixture into its component parts, or fractions, such as in separating chemical compounds by their boiling point by heating them to a temperature at which several fractions of the compound will evaporate. ... A fractionating column is an essential item used in the distillation of liquid mixtures so as to separate the mixture into its component parts, or fractions, based on the differences in their volatilities. ... The graphical approach presented by McCabe and Thiele in 1925, the McCabe-Thiele Method is considered the simplest and perhaps most instructive method for analysis of binary distillation. ...

External links

• Lecture Notes (R.M. Price, Christian Brothers University, Tennessee)
• Studies in Chemical Process Design and Synthesis, Y. A. Liu, T.E. Quantrille, and S. Chengt, Ind. Eng. Chem. Res., Volume 29, 1990
• Multi-component Distillation (M.B. Jennings, San Jose State University)

Christian Brothers University is the oldest college in the city of Memphis, Tennessee. ... San Jose State University San José State University, commonly shortened to San Jose State and SJSU, is the oldest university in what became the California State University system. ...

References

1. ^ Fenske, M.R. (1932). Ind.Eng. Chem., Vol. 24: 482.
2. ^ ^{a b} Distillation notes (Loren Schreiber, Florida State University)
3. ^ ^{a b} Lecture 13: Fenske Equation (Queens University, Canada)
4. ^ Tutorial 6: Separation Processes (J. Skilling, University of Edinburgh, Scotland)
5. ^ Maxwell, J.B. (1950). Data Book on Hydrocarbons, 1st Edition, D. Van Nostrand. 
6. ^ Fenske Equation (U.S. Naval Academy)