In-situ measurement of residual carbon content in flyash

An on-line carbon-in-ash monitor based on in-situ infrared emission spectrometry is described. Laboratory measurements of the infrared spectral emissivity of flyash are presented in order to demonstrate that emissivity can be correlated to the residual carbon content in the range of interest for pulverized coal-fired power plants. Data collected during a field test at a pilot-scale combustor are presented in order to demonstrate that the emissivity measurements could be made in situ on a realistic facility, and that the spectral emissivity could be correlated to the residual carbon content. Since this measurement can be made in-situ in a few seconds using an FT-IR spectrometer, an infrared emissivity based carbon-in-ash monitor will be capable of providing data on a time scale appropriate for implementation in combustion control strategies while avoiding the disadvantages associated with extractive ash sampling.