Unit Operation Blocks Used in this Book

2 UNIT OPERATION BLOCKS USED IN THIS BOOK 

In the following, the unit operation blocks in Aspen Plus that are used in this book will be explained. 

The RadFrac block can be used for the ordinary distillation column and also for the extractive distillation column as shown in the example in Section 3.1. It can also be used as strippers (with a reboiler but no condenser), rectifiers (with a condenser but no reboiler), absorbers (with neither), and more complex columns with side pmnp-around. In the following, several columns other than the ordinary distillation will be outlined. The RadFrac can also be used as a heterogeneous azeotropic distillation column with decanter replacing the reflux drum at top of this column. The vapor-liquid-liquid calculation can be performed inside the column if needed. 

Sidestream Column. The RadFrac block in Aspen Plus can be used for the ordinary distillation column with one feed stream and two outlet streams (distillate and bottoms). This block can also be used for multiple feed streams or more than two ordinary outlet streams. For example, the extractive distillation column in Section 3.1 demonstrated that two feed streams can be connected to the RadFrac block. In a similar way, more outlet streams can be drawn out of the RadFrac block as a sidestream column. The sidestream draw-off can be either a liquid stream or a vapor stream. AU these varieties of different columns can easily be configured by adding material streams to the flowsheet with the RadFrac block (see previous Fig. 3.5). 

Stripper. In Chapter 7 of this book, two strippers are used togefliCT with a decants to 

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Finally, when the Gantt chart prepared by BATCH PLUS is extended to show three batches, as shown in Figure 4.27d, the bottleneck of the process is determined quite easily. For each vessel, solid blocks show the time period during which it is in operation. Solid blocks are for the first, second, and third batches, respectively. The bottleneck is associated with the equipment unit that is utilized at all times that is, for which the red, blue, and green blocks touch each other. Clearly, this unit determines the cycle time. Note that these results can be reproduced using the folder BATCH PLUS-EXAM 4-5 on the CD-ROM that accompanies this book. ... 

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