CHEE 4703: Process Dynamics and Control

CHEE 4703: Process Dynamics and Control Fall 2024 

Lab 3: Root Locus Diagram and Controller Tuning 

Process Background 

Consider a blending process with two inlet streams and a single (overflow) outlet stream. The 

schematic diagram of the process is shown in Figure 1, where x1, x2 and x represent the mass 

fraction of component A and w1, w2 and w represents the overall mass flow rate. One of the inlet 

streams, stream 1, is made up of compound A (and the balance compound B). The mass fraction 

of A is a disturbance variable and has a steady state value of 20% (with a total steady state flow 

rate of 1 kg/min). The other inlet stream, stream 2, is made up of pure B, where the flow rate is a 

manipulated variable. The outlet mass fraction of A is a controlled variable with a target of 10%. 

Assume that there is 10 kg of liquid in the tank (constant volume with a density similar to water). 

Figure 1. A blending process in a CSTR. 

Process Parameters 

The process operating conditions are as follows: 

Constants Input Steady State Conditions 

V 10 L ̅̅̅1̅ 1 kg/s 

ρ 1 kg/L ̅̅1̅ 0.2 

x2 0 ̅̅̅2̅ 1 kg/s 

Output Steady State Condition 

 ̅ 0.1 

 CHEE 4703: Process Dynamics and Control Fall 2024 

Kathy Isaac, Stanislav