A Non-Intrusive Sodium Line Emission Pyrometer for Coal Combustor Temperature Measurement

A sodium line emission pyrometer (SLEP), which relies on the detection of the thermal emission from sodium naturally occurring in coal, has been successfully utilized to perform non-intrusive temperature measurements in a coal combustor. The SLEP technique incorporates an aerodynamic window optical access port for clean unobstructed view of the combustion region, a fiber optic to transfer the collected emission from the combustor to a detector, a high reolutin echelon spectrometer to spectrally isolate sodium emission at 589.0 nm, and a linear detector array and optical multichannel analyzer for subsequent data analysis. Measurements were performed during many hours of operation in TRW's 17 inch slagging cyclone coal combustor with no degration in either optical access or in a signal integrity. The temperatures were calculated from the measured sodium emission intensity using the Planck blackbody equation. Temperatures between 1700K and 2000K were measured in the combustor with a typical accuracy better than +-10k. Rapid fluctuations in the measured temperature could be followed on millisecond time scale.