DEGENERACY OF DECOUPLING IN DISTILLATION-COLUMNS

An interacting control system may be internally decoupled through the use of noninteracting manipulative variables. Application of this concept to dual composition control of a binary column (q = 1) leads to the unexpected result that the conditions for half-decoupling of either loop are effectively the same. This degeneracy very closely approximates the column material balance and makes it impossible to completely decouple the system. The findings appear to be of general validity and afford insight into the success of the Shinskey material balance control scheme. © 1978, American Chemical Society. All rights reserved.