In Section M13.3, the composition control loops were tuned independently using the IMC-based PI technique, neglecting time delays. The control system was simulated assuming a 2-minute time delay on all measurements. The IMC filter factors (λ1, λ2) were both set to 25 minutes, one third of the process time constant. Here, we show the responses for both loops closed simultaneously. The response for a setpoint change of 1 mol% (0.01 mole fraction) in the distillate composition is shown in Figure M13-6. Note that the controllers are highly interacting and the response time is extremely slow (the outputs are still far from the setpoint after 1000 minutes).