Why are two columns in series usually used in extractive distillation?
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As the title suggests: is it because there are many extraction stages, and making one tower too tall, that two towers are used instead?
It is mainly due to the three components
Solvent recovery and recycling need to be considered; the second tower is used for recovery
The common reason is that making one tower too tall; therefore, two towers are used. However, it also depends on the design principles and intentions – whether solvent recovery is intended, as solvents need to be recovered and reused.
The first column is used for extractive distillation, while the second column is used for solvent recovery