An improved colorimetric method for visualization of 2-D, inhomogeneous temperature distribution in a gas fired industrial furnace by radiation image processing

Abstract

The reconstruction of multi-dimensional, inhomogeneous combustion temperature distribution inside industrial furnaces through flame radiation images is very difficult. This is because the radiation contributed to the radiation images from the high temperature furnace wall surfaces is higher than that from water-cooled tubes in utility boilers. Based on the monochromatic intensity distributions reconstructed from the monochromatic intensity images transferred from color flame images through the Tikhonov regularization method, the colorimetric method is extended to infer the multi-dimensional, inhomogeneous temperature distribution inside industrial furnaces from the ratio of the two monochromatic intensity distributions. In order to set proper radiative properties used in the colorimetric method, the monochromatic method is used to simultaneously reconstruct the temperature distributions and the radiative properties of the combustion medium by an iterative algorithm. The experiments were conducted in a walking beam reheating furnace using 8 flame image detectors and image processing technique. The temperatures measured using 8 thermocouples are used to validate the reconstructed temperature distributions. The temperatures visualized by the monochromatic and colorimetric methods agree with those measured using the thermocouples. The colorimetric method is proved to be more robust and accurate than the monochromatic method through on-line, 24-h temperature monitoring data in the furnace.