The outlet temperature of the process fluid and the oxygen in the flue gas can be controlled in the fired heater by adjusting the fuel pressure (flow) and the stack damper % open. A dynamic model for the fired heater in was reported by Zhuang et al. (1987) and is repeated here.
The inputs and outputs are in percent of the range of each instrument, and the time is in sec.
(a) Determine whether the input-output combination is controllable.
(b) Determine whether either loop pairing can be eliminated based on the sign of the relative gains.
(c) Determine whether decoupling will improve the control performance.
(d) Determine the PI controller tuning for the best multiloop control, with or without decoupling.
