Hengstebeck

R. J. Hengstebeck, Petroleum Processing, Principles and Applications, McGraw-HiU Book Co., Inc., New York, 1959. 

For multicomponent mixtures the method of Hengstebeck can be used. Kister s book Distillation Design, by McGraw-Hill, 1992 explains the method and is easier to find than the original book of Hengstebeck. 

Hengstebeck, R. J., Distillation-Principles and Design Practices, Reinhold Publishing, 1961. 

To determine the reasonableness of the top and bottom compositions of a fractionation column, a Hengstebeck plot is fast and easy (Reference 4). First, select a heavy key component and determine the relative volatility (a) of all column components to the heavy key. The a can be otfeed or perhaps more accurately cc = (a,op oCboitom) - Plot In D/B versus In a and the component points should fall close to a straight line. If a fairly straight line does not result, the compositions are suspect. A nomenclature table is provided at the end of this chapter. 

Hengstebeck [137] presents a simplified procedure for reducing a multicomponent system to an equivalent binary using the key components. From this the number of stages or theoretical plates and reflux can be determined using conventional binary procedures and involving the McCabe-Thiele method. 

The distribution of components for the distillate and the bottoms is given by the Hengstebeck-Geddes equation [124,125, 126] ... 

Hengstebeck [224] presents a technique for locating the feed tray by plotting. 

Hengstebeck, R J., Finding Feed Plates from Plots, Chem. w -.july 29 (1968), p. 143. 

Only a brief review of the fundamental principles that underlie the design procedures will be given a fuller discussion can be found in Volume 2, and in other text books King (1980), Hengstebeck (1976), Kister (1992). 

Efficient techniques for the solution of the trial and error calculations necessary in multicomponent flash calculations are given by several authors Hengstebeck (1976) and King (1980). 

Hengstebeck s method is used to find the third trial value for L/V. The calculated values are plotted against the assumed values and the intercept with a line at 45° (calculated = assumed) gives the new trial value, 2.4. 

Where the concentration of the non-keys is small, say less than 10 per cent, they can be lumped in with the key components. For higher concentrations the method proposed by Hengstebeck (1946) can be used to reduce the system to an equivalent binary system. Hengstebeck s method is outlined below and illustrated in Example 11.5. Hengstebeck s book (1976) should be consulted for the derivation of the method and further examples of its application. 

Hengstebeck shows how the method can be extended to deal with situations where the relative volatility cannot be taken as constant, and how to allow for variations in the liquid and vapour molar flow rates. He also gives a more rigorous graphical procedure based on the Lewis-Matheson method (see Section 11.8). 

The graphical procedure proposed by Hengstebeck (1946), which is based on the Fenske equation, is a convenient method for estimating the distribution of components between the top and bottom products. 

Hengstebeck and Geddes (1958) have shown that the Fenske equation can be written in the form ... 

Chang (1980) gives a computer program, based on the Geddes-Hengstebeck equation, for the estimation of component distributions. 

Use the Geddes-Hengstebeck method to check the component distributions for the separation specified in Example 11.5... 

Efficient procedures for adjusting the compositions to achieve a satisfactory mesh at the feed point are given by Hengstebeck (1976). 

The basic theory of batch distillation is given in Volume 2, Chapter 11 and in several other texts Hart (1997), Perry et al. (1997) and Walas (1990). In the simple theoretical analysis of batch distillation columns the liquid hold-up in the column is usually ignored. This hold-up can have a significant effect on the separating efficiency and should be taken into account when designing batch distillation columns. The practical design of batch distillation columns is covered by Hengstebeck (1976), Ellerbe (1997) and Hart (1997). 

HENGSTEBECK, R. J. (1946) Trans. Am. Inst. Chem. Eng. 42, 309. Simplified method for solving multicomponent distillation problems. 

Hengstebeck, R.J., Jr. Distillation -Principles and Design Practice, Reinhold, New York, 1961. 

Hengstebeck, R.J. An Improved Shortcut for Calculating Difficult Multicomponent Distillations, ... 

Hengstebeck, R. J. 1959. Petroleum Processing Principles and Applications. New York McGraw-Hill Book Company. 

R.J. Hengstebeck, Distillation principles and design procedures, Reinhold Publishing Co., New-York (1961). 

The distribution of nonkeys actually depends somewhat on the reflux ratio. For instance, in the case of Example 13.10, the distributions at minimum trays (total reflux) and minimum reflux are substantially different. Often it turns out, however, that the distributions predicted by Eq. (13.119) are close to those at finite reflux whenever R is near 1.2Rm, which is often near the economic value for the reflux ratio. Further discussion of this topic is by Hengstebeck (Distillation, 1961) and Stupin and Lockhart (1968) whose work is summarized by King (1980, p. 434). Knowledge of the complete distribution is needed for estimation of top and bottom temperatures and for determination of the minimum reflux by the method to be cited. 

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