Question: Sketch the root locus diagram for the reactor composition control loop of Problem.

Problem: you are asked to model three mixing tanks in series. Find the ultimate gain and period of a proportional controller that is to control the outlet composition from the third tank, Qt), by manipulating the flow of water into the first tank,fl(t). Assume an equal percentage control valve with constant pressure drop and (Y = 50. The analyzer transmitter has a range of 0.30 to 0.70 mass fraction units, and the time constants of the valve and transmitter can be neglected. Also draw the block diagram of the loop and calculate the offset caused by a change of 10 gpm in flow f2 when the controller gain is set equal to onehalf the ultimate gain.