Coordinated control of blending systems

Blending is an important unit operation in chemical process industries. Based on Luyben´s work (1990), a coordinated control is proposed to overcome the system interaction and process nonlinearity in blending processes. Blending systems with ideal and nonideal mixing are explored. Furthermore, unusual dynamic behavior is observed for blending systems coupled with complex dynamics arisen from the process side. Controlling the blending of streams from different sidestream locations of a distillation column is studied and, based on physical insight, a simple procedure is proposed for the selection of sidedraw locations. The disturbance rejection aspects of blending control are discussed and practically important issues such as model uncertainties and measurement noise are also treated. Simulation results show that the control of blending systems is not as trivial as it was thought and, more importantly, improvement in the performance can be achieved using the proposed coordinated control