A Study of Sootblower Erosion in Waste-Incinerating Heat Boilers

Abstract

A numerical three-dimensional (3D) simulation was performed on the flow of a particle-laden steam jet impinging on the tubes of the superheating section of a waste-burning industrial boiler: the study was conducted to investigate the causes of excessive erosion systematically detected under otherwise normal operation. Prior experimental evidence had led to the identification of the slag particles as a possible agent for such an erosion: these particles are removed from the surface of the first row of the tubes by the steam jet ejected from the sootblower, and may cause erosion if they impinge on the tubes of the following (upstream, in the direction of the gas path) rows. Three sootblower configurations were considered to analyze this presumed phenomenology of tube erosion. The (significant) effects of turbulence on the motion of the solid particles are taken into account by means of a stochastic flow model. The simulation generates a prediction of the particles trajectories, both in a geometrical sense (to locate the portions of the tube surfaces on which the individual particles may impinge) and in a statistical one (to identify the relative frequency of the impacts on each portion of surface): the erosion rate for each sootblower configuration has been calculated on the basis of the impact frequency indicated by the numerical calculations.