Question: In a monograph on plantwide process control, Luyben, Tyreus, and Luyben (1998) discuss the potential accumulation of reactants in reactor-recycle systems. They suggest that one flow rate in the recycle loop should be on flow control, not adjusted by a level controller.
(a) Discuss the rationale for this suggestion.
(b) Apply this suggestion to the solved example in this chapter (both De signs I and II), and sketch the control designs on copies of Figure.
(c) Discuss the expected performance for the disturbances defined in the control design form.
