Abstract: A liquid level control principally for boiling water boilers sensitive to the presence or absence of liquid at an upper and at a lower control level. The control enables the boiler to be fired when liquid is at or above the upper level. It prevents firing and enables addition of make-up liquid when the liquid level is below the upper control level, except when the system indicates there is liquid at the upper control level, and that there is no liquid at the lower control level.

Abstract: A system to maintain the BTU output of a rotary drum, in which steam is supplied to the drum, and in which saturated steam and condensate is drained therefrom. An upstream flow meter and a downstream flow meter measure fluid flow, and in view of the small partial pressure of the condensate and of the large volumetric difference between the condensate and the steam which was condensed, the difference between the flow meter readings can be understood as a measure of BTU's provided as a consequence of the condensation which occurs in the drum.

Abstract: A monitor for the boiler water level in a boiler tube extends from the upper portion of the steam drum to the lowest water drum, header, or the like, and sensors are placed along its length which are responsive to the presence or absence of liquid water at the respective elevation. The condition of the various sensors can be utilized to read out the level of water in the system. The tube can be an external equalizer tube that extends between two extreme elevations, or can be a plurality of segments each extending for only a portion of the total height.

Abstract: A furnace containing a burner, supplied by fuel to be ignited at the burner, in the presence of air, is provided with a viewing duct for viewing the flame and means for detecting the radiation intensity at a plurality of different wavelengths of the radiation spectrum. The output from the detector is amplified and integrated and a signal representing the ratio of intensities at the selected wavelengths is applied to an indicator to indicate fuel-air ratio and also is applied to control means for the fuel flow or the air flow, or both, to control the fuel-air ratio at the burner and to maintain it substantially constant at a desired value. This can be done at more than one burner, providing balanced furnace operation. With this balanced furnace, there is improved firing efficiency, resulting in fuel saving and lowered pollution emissions. A computer type master controller can be used to correlate the fuel-air ratios for the individual burners.