Optical Pyrometry for In-Furnace Temperature Monitoring and Combustion Control

A novel adaptation of optical pryometry has been developed for in-furnace temperature monitoring. Non-intrusive, continuous measurement of either gas or flame temperatures is possible in the temperature range 1000° to 4500°F. Use of the monitor has been shown to allow better control of the combustion process which in turn leads to lower pollutant emission, higher efficiency, and less damage to boiler components. The technique is based on measurement of the radiation emitted by ash, char or soot particles, and has been successfully demonstrated at a number of pulverized-coal-fired utilities where furnace exit gas temperature was monitored. The monitor has also been used in a full scale waste-to-energy plant, and plans are under way to apply the monitor for control of selective non catalytic NOx reduction, and to monitor flame temperature in high-temperature industrial processes with low accessibility for measurements such as cement kilns. In this paper, a description of the instrument is given, along with details of the applications for utility and industrial combustion processes, and the ways which pollution emissions can be improved. Finally a listing of the demonstrations to date with some specific experience at an eastern utility will be given.