Figure 2: A cross-limiting combustion circuit allows firing multiple fuels simultaneously without
risking excess fuel.
Burner modulation
Modulating control improves boiler operation by monitoring the steam or hot-water line to
produce a continuous control signal that determines the fuel input. Reductions in steam
pressure or water temperature lead to an increase in firing rate. The advantages of burner
modulation for combustion control include:
Continuously matching fuel and air rates to demand.
Closer steam pressure or water temperature tolerances.
Improving boiler efficiency.
Reducing the weighted average flue-gas temperature.