13. Concept of Feedback Control Process m d y Process m d y Final Control Element Sensor/ transmitter Controller y sp y m c e Open loop Closed loop Controller Mechanism - +
15. Typical Feedback Control Systems Pressure Control Liquid-Level Control
16. Typical Feedback Control Systems Temperature Control Liquid-Level Control
17. Representation of Feedback Loops FC for flow control PC for pressure control LC for liquid-level control TC for temperature control CC for composition control FT for flow transmiser PC for pressure transmiser LC for liquid-level transmiser TC for temperature transmiser CC for composition transmiser
18. Representation of Feedback Loops Example Control valves on a flash drum See also Apendix A of A. Smith and A. B. Corripio, Control Automático de Procesos, Limusa