Heater damper controller

Claim 1

Apparatus for controlling a stack damper for maintaining stack oxygen content at an optimal level for minimizing fuel consumption of an associated heater in view of process conditions, comprising: monitoring means for providing condition signals representative of a plurality of combustion process variables, said monitoring means measuring the excess stack oxygen level and generating an excess stack oxygen signal; operator input means manually operable for permitting the operator to generate target data representative of an excess stack oxygen target value; damper control means responsive to a damper control signal for positioning the damper according to said control signal; and control means including: (1) feedforward control responsive to said condition signals for generating a damper control signal for positioning the damper at a position for substantially providing an oxygen level anticipated for combustion; (2) feedback control responsive to said target data and said excess stack oxygen signal for generating a said damper control signal for positioning the damper at a position for substantially providing an oxygen level dictated by said target value; and (3) timing control responsive to said feedforward control demand for increasing combustion for inhibiting operation of said feedback control for a period of time.