Gilliland correlation

FIG. 13-41 Comparison of rigorous calcnlations with Gilliland correlation. [Henley and Seader, Eqnilihrinm-Stage Separation Operations in Chemical Engineering, Wiley, New York, 1981 data of Van Winkle and Todd, Chem. Eng., 78(21), 136 (Sept. 20, 1971) data of Gilliland, Elements of Fractional Distillation, 4th ed., McGraw-Hill, New York, 1950 data of Brown and Maiiin, Trans. Am. Inst. Chem. Eng., 35, 679 (1.93.9) ]... 

The Gilliland correlation [23] of Figure 8-24A has proven satisfactory for many binary as well as multicomponent mixtures over a wide range of reflux ratios and number of plates. 

Liddle [136] presents a shortcut technique for multi-component calculations based on improving the Fenske and Gilliland correlations. 

The Gilliland correlation appears to be conservative for feeds with low values of q (the thermal condition of the feed), and can be in error when there is a large difference in tray requirements above and below the feed. The principal value of the correlation appears to be for preliminary exploration of design variables which can be refined by computer calculations. Although it is often used for final design, that should be done with caution. Other possibly superior but more difficult to use correlations have been proposed and are described in standard textbooks for example, Hines and Maddox (1985). 

Figure 3,9 Reflux-stages correlations, (a) The Gilliland correlation...

FIGURE 8.4 Gilliland correlation relating number of stages to reflux ratio. (From Chemical Engineering, McGraw-HUl, 1977.)... 

Fraction of a component in feed vapor that is not absorbed Fraction of a component in entering liquid that is not stripped Factor in Gilliland correlation... 

Calculate the number of equilibrium stages, N, from the Gilliland correlation, (Equations 6.27.8 to 6.27.11). 

Gilliland correlation, trays, 397 Molokhanov equation, 397 Globulation, 351 Glossary... 

The Gilliland correlation uses the results of the Fenske and Underwood equations to determine the actual number of equilibrium stages. The correlation has been fit to three equations ... 

Solve the Gilliland correlation for the actual number of equilbrium stages. 

An empirical but much easier to use method is the Gilliland correlation. This is an empirical relation between the number of ideal stages and the operating reflux ratio. You also need to know the minimum number of ideal stages (at total reflux) and the minimum reflux ratio. Because of its simplicity, this correlation is widely used for preliminary estimates. 

Note in this description the words reflux rate and reflux ratio. They are different, and you need to be careful to use the right one, since using too small a reflux rate could make your column not work. Finally, you use the Eduljee version (Eduljee, 1975) of the Gilliland correlation (Gilliland, 1940) [Eq. (6.6)] to find the actual number of stages. This equation correlates data on roughly one-hundred distillation columns. You must specify either the reflux ratio (R) or number of stages (S) in order to use this equation. 

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