Modeling of Simulated Moving Bed SMB Separations

Zone I, between the eluent and the extract ports where desorption of the more retained component takes place, 

Zone IV between the raffinate and the eluent ports where adsorption of the less retained component takes place. 

Each zone may have a different number of coliunns. Zones II and III contain the overlapping region of the two migrating bands. These two zones are needed for the separation and are called the separation zones. Zones I and IV are used to recover the extract and the raffinate products and to prevent cross contamination. They are called the buffer zones. 

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