Abstract
Heat-exchanger tubes in fluidized bed combustors (FBCs) often suffer material loss due to combined corrosion and erosion. The effect of chlorine on in-bed tube wastage and its possible mechanism are being studied using the EPRI/LBNL FBC wastage simulator. This test rig was designed to simulate dense particle impacts on tube bottoms with well-controlled parameters, and has been proven to closely reflect situations found in operating bubbling FBCs. In this study, HCl gas was chosen to be the Cl source and was introduced into the fluidizing air with a 50-ppm concentration. Tests were performed at temperatures ranging from ambient to 400°C using 1018 low carbon steel rods in a bed of commercial SiO 2 sand that had an average size of 800 μm. The wear profile after each test was measured using a profilometer. Results showed an increase in material wastage rates in the presence of HCl, and that the rate was significantly higher with higher test temperatures. Microstructural and chemical analysis of the wear surface and corrosion products are reported. It is concluded that the dominating effect of HCl on the wastage rates is due to an enhanced oxidation and a reduced scale adherence.
Published Version
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