Advanced monitoring of the fouling process on water walls

During the combustion of fossil fuels in a steam generator, slagging and fouling of the combustion chamber occurs which hinders the heat transfer, declines the steam generator performance and promotes corrosion of the water-tube walls. Due to the deposition and its noticeable impact on the operation of the steam generator, there is a need to clean the heat exchanger surfaces during operation. A demand-actuated cleaning requires information about deposits on water walls regarding their thicknesses, structures and strengths. Previously we have described a concept that characterizes the material properties of deposits on water-tube walls analyzing the unsteady temperature field within the deposit (Grahl and Beckmann, 2013). In this paper the applicability of the concept is discussed and was tested in a steam generator of a waste incineration plant. The concept was found to be sufficiently accurate regarding thickness changes due to fouling as well as cleaning processes.