Boiler control having a heating value computer and providing improved operation with fuels having variable heating values

摘要

A boiler control regulates the input fuel and air to satisfy load demand. Simultaneously, fuel flow is adjusted by fuel flow control to correct for changes in fuel heating value. A computer circuit which generates a heat balance ratio of outlet steam flow and input mass fuel flow as a representation of imbalance between presumed heat input and actual heat output and by inference from the imbalance or change in fuel heating value. The heat balance ratio is multiplied against an actual fuel feedback signal and the ratio corrected signal is applied to the fuel flow control.