Flame three-dimensional tomography sensor for in-furnace diagnostics

An optical diagnostic technique for measuring three-dimensional flame temperature distributions in a furnace, making use of new emission tomography reconstruction algorithms, is presented. The new approach aims to overcome the limitations of previous applications of emission tomography to flames, which did not consider radiation absorption inside the flame and where radiation from the hot wall surfaces constituted a major problem, mainly because the reconstruction algorithms did not allow for the inclusion of an absorption correction term. This constituted a major limitation to the accuracy of the technique. In this paper, an experimental setup, together with dedicated tomographic reconstruction algorithms that include a flame radiation absorption model, was developed and tested in non-premixed laboratory propane flames. The resulting sensor prototype was used on semi-industrial confined fuel-oil flames, and the measurements obtained indicate that the new technique reconstructs the three-dimensional temperature fields of axisymmetric and non-axisymmetric flames, with uncertainties below +/- 10%, provided that soot is available.