Multicomponent batch distillation column design

Abstract

Batch distillation is characterized as a system that is difficult to design because compositions are changing continuously with time. The models reported in the literature and used in the simulators like PROCESS and BATCHFRAC, etc., are too complex to use for obtaining optimal design because of high computational time and large memory requirement. In this work we are presenting a short-cut method for design of multicomponent batch distillation columns, operating under variable reflux and constant reflux conditions. The method is essentially a modification of the short-cut method widely used in the design of continuous multicomponent columns. The technique has been tested for both binary and multicomponent systems, and the results compare favorably with the rigorous methods of design. The method is very efficient and can be used for preliminary design and analysis of batch columns. The model used in this method has a number of tuning parameters that can be used for model adaptation. The main features of the short-cut method include lower computational time (which is independent of the number of plates in the column), lower memory requirements, and its adaptability to design.

Design of Batch Distillation Columns Using Short-Cut Method at Constant Reflux

“…From the papers of Diwekar and Madhavan [2] and Sundaram and Evans [3] for constant reflux ratio, we found that both methods were similar and differed only in small details. Seader and Henley [9,10] used the sequence of equations shown in Table 2 that apply FUG method.…”

“…It was probably Diwekar [1] in her 1988 Ph.D. dissertation who first reported the short-cut method for batch distillation columns, but we think that Diwekar and Madhavan paper [2] is considered the first in a known journal. Their paper described both constant and variable reflux.…”

Performance Indices to Design a Multicomponent Batch Distillation Column Using a Shortcut Method

“…D. dissertation who first reported the shortcut method for batch distillation columns and the paper by Diwekar and Madhavan (1991) is considered to be the first in a major journal. Their paper described both constant and variable reflux.…”

“…A part of the procedure followed by Diwekar and Madhavan, 1991 was combined with the procedure used by Seader and Henley (2006) (Section 13.6) for constant reflux for variable reflux and constant composition for a light component that is the reference component, but now the minimum reflux calculation is more general. …”

“…With the equations of Table 2 computer programs in Excel were prepared, validated with the data of Diwekar and Madhavan (1991) and then applied to the four component problem. For this separation, benzene is collected as distillated product with mole fraction of 0.97 and the reflux ratio is adjusted (increased) to get that result; the mixture of toluene, ethyl-benzene and o-xylene are concentrated in the pot.…”