Distillation shortcut design

For shortcut design of a distillation column, the minimum reflux calculation should be made first. 

Algebraic Method for Binary Distillation Calculation 392 Shortcut Design of Multicomponent Fractionation 396 Calculation of an Absorber by the Absorption Factor Method 399... 

Bausa, J. and W. Marquardt, 2000, Shortcut Design Methods for Hybrid Membrane/Distillation Processes for the Separation of Nonideal Multicomponent Mixtures, Ind. Eng. Chem. Res., 39, 1658-1672. 

Truly multicomponent solutions based on continuous distillation shortcut methods have been proposed for batch distillation. The Fenske, Underwood, and Gilliland equations or correlations are commonly used in conjunction with each other to solve continuous distillation problems as described in Section 12.3. Diwekar and Madhavan (1991) describe how these techniques may be modified for the design of batch distillation columns for variable and constant reflux cases. 

The two important design elements of a distillation column are the number of theoretical stages N, and the reflux R ratio. If the mixture is zeotropic, they are related, as illustrated in Fig. 9.35-a. There is a minimum number of theoretical stages as well as a minimum reflux both depending on the sharpness of separation. For zeotropic mixtures with n-components, the shortcut design procedure known as Fenske-Underwood-Gilliland (FUG) method is well-established (Perry s handbook, 1997). 

The design of the distillation column must take into account the operation in recycle. In a first approximation we use a shortcut design imposing as specifications in top 95% recovery of B and 0.01% of A. The purity of B in distillate is better than 99.8 %, while the fraction of B in bottoms is kept at less than 5 %. A number of 35 theoretical stages is found for 1.3/ niin, but we consider 40 stages to ensure some flexibility. 

Bausa, J. and W. Marquardt, Shortcut design methods for hybrid membrane/distillation processes for the separation of nonideal multicomponent mixtures. Industrial and Engineering Chemistry Research, 2000, 39(6) 1658 1672. 

Approximate distillation Shortcut Column Fenske-Underwood design... 

Using the flowsheet simulators, design calculations are needed to estimate the reflux ratio and the theoretical tray requirements for the two towers in each of the sequences. In ASPEN PLUS, this is accomplished with the DSTWU subroutine, which is described in the module ASPEN — Separators Distillation FUG Shortcut Design on the multimedia CD-ROM. 

Shortcut Design of Multicomponent Distillation Tower. A feed of part liquid and... 

Shortcut Design Method for Distillation of Ternary Mixture. A liquid feed at its bubble point is to be distilled in a tray tower to produce the distillate and bottoms as follows. Feed, x p = 0.047, Xpp = 0.072, = 0.881 ... 

The shortcut design is completed by calculating the heat quantities in the feed, distillate, bottoms and the condenser duty. The reboiler duty is then calculated by difference as... 

Frank, O., Shortcuts for Distillation Design, Chemical Engineering, March 14, 1977. 

Efficient and economical performance of distillation equipment is vital to many processes. Although the art and science of distillation has been practiced for many years, studies still continue to determine the best design procedures for multicomponent, azeotropic, batch, raul-tidraw, multifeed and other types. Some shortcut procedures are adequate for many systems, yet have limitations in others in fact the same might be said even for more detailed procedures. 

For single separation duty, Al-Tuwaim and Luyben (1991) proposed a shortcut method to design and operate multicomponent batch distillation columns. Their method, however, required a great number of simulations, which must be computationally very expensive, before they could arrive at an optimum design and find an optimum reflux ratio. Further details are in Chapter 7. 

Rmin and the corresponding number of trays calculated ( 2N J. The shortcut models were replaced by rigorous RADFRAC units, where the reflux and distillate feed ratio were adjusted by means of design specifications, in order to meet the desired separation. The trays were sized using Aspen s facilities. Finally, the dimensions of the reflux drum and column sump were found based on a residence time of 5 min and aspect ratio H D = 2 1. Table 9.7 presents the results of distillation column sizing. 

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