Reboiler and Column-Base Composition Dynamics

The phenomenon of inverse response was apparently first noted by Rijnsdorp. As mentioned in Chapter 13, it occurs in some columns when an increase in vapor flow causes a momentary increase in liquid flow down the column. This is due to a decrease in foam density on the trays and a consequent momentary overflow into the downcomer. 

The significance c inverse response in the design cS. feedfeaward compensatcM s and feedback controllers for composition is discussed later. It is the subject of a paper by Luyben.  

Signal flow diagram for reboiler composition dynamics 

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