CO CONTROL HEIGHTENS FURNACE EFFICIENCY.

Air infiltration into a furnace often renders oxygen measurement questionable, even useless. Yet a carbon monoxide analyzer measuring the same flue gas can extract useful data and provide correct control action. The CO analyzer measures the reaction at the flame's tip. Therefore, dilution from excess air, or infiltration from leakage or maladjusted burner registers, will not cause the measured data to be meaningless. A typical fuel-and-air-flow-metering combustion control system is shown in Fig. 2, and a typical steam-and-air-flow-metering combustion control system in Fig. 3. The steam flow (as Btu of heat leaving the boiler) divided by the boiler efficiency represents the heat input of the unmetered fuel (coal). The measurements of CO in flue gas is described in some detail with emphasis on precision of instruments and their operations. Calculations are presented which show how fuel can be saved.