12th International Conference on Fluidized Bed Technology LABORATORY SCALE STUDIES OF SOLID-PARTICLE EROSION IN BOILERS

A method to study the effects of different parameters affecting the erosion of steels and refractories used in fluidized bed boilers was developed. The method allows quantifying the contribution of key parameters on erosion, to compare the erosivity of different erosive materials, and to rank different boiler materials based on their erosion resistance. Two boiler materials were used to test the method; 10CrMo9 and AISI 347. In the method, a gas-blast type erosion test rig was used to erode the surfaces at various conditions. The materials were eroded with ash and olivine sand at various temperatures and particle velocities. To quantify the erosion, detailed analysis of the surface morphology was made before and after the erosion using a confocal optical microscope (COM). Additionally, the surface after the exposure was characterized by the means of scanning electron microscopy with energy dispersive X-ray spectroscopy (SEM-EDX). The results showed that at high erosion velocities the erosion rates as measured by analyzing the surface profiles with COM were in accordance with the weight change, while the COM analyses provided more detailed information about the surface changes after the erosion process. At low particle velocities, some deposit was formed on the sample leading to false erosion rates by using weight change analysis. Thus, the study of the surface profiles and their comparisons provide clearer information of the actual material undergoing erosion. In certain cases, such as higher temperature tests, where oxidation-corrosion complicates the erosion process, the profile analysis with COM gave better erosion information compared to the weight change measurements.