CONSTILL - Continuous Binary Distillation Column

For simplicity, a column containing a total of eight theoretical plates plus a reboiler is assumed, with the feed entering on plate 5, numbered from the column top, as described in Sec. 3.3.3.3. 

Assuming theoretical plate behaviour in the column, the equilibrium is calculated by 

9 (in program) Refers to flows below the feed plate  

Study the response of the column to changes in the operating variables feed rate, feed composition and reflux ratio. 

Verify that the overall steady-state balance is attained. 

A continuous binary distillation column is represented below. The column is shown in Fig. 1 as consisting of eight theoretical plates, but the number of plates in the column may be changed, since the Madonna program is written in array form. 

5 Simulation Tools and Examples of Chemical Engineering Processes 

Note that the total number of plates, the feed plate location and reflux ratio can all be varied during simulation. The array form of the program also allows graphing the axial steady state tray-by-tray concentration profile. Part of the program is shown below 

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CONSTILL - Continuous Binary Distillation Column System... 

Continuous binary distillation is illustrated by the simulation example CONSTILL. Here the dynamic simulation example is seen as a valuable adjunct to steady state design calculations, since with Madonna the most important column design parameters (total column plate number, feed plate location and reflux ratio) come under the direct control of the simulator as facilitated by the use of sliders. Provided that sufficient simulation time is allowed for the column conditions to reach steady state, the resultant steady state profiles of composition versus plate number are easily obtained. In this way, the effects of changes in reflux ratio or choice of the optimum plate location on the resultant steady state profiles become almost immediately apparent. 

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