EROSION CORROSION OF 1018 STEEL ERODED AT LOW VELOCITIES BY CFBC BED MATERIAL

The erosion-corrosion (E-C) behavior of 1018 carbon steel eroded by fluidized bed combustor (FBC) bed material particles at low elevated temperatures and low particle velocities was determined in a nozzle-type laboratory tester. Bed material erodent particles from operating, circulating fluidized bed combustors were used for tests in air at different temperatures from 25 to 550-degrees-C for exposure periods up to 100 h at particle velocities as low as 2.5 m s-1. The lowest velocity test conditions were meant to simulate those experienced by in-bed FBC heat exchanger tubes. Metal wastage rates were determined from thickness loss measurements of the specimens. It was determined that particle velocity influenced the relationship between metal wastage and test temperature. At the lowest particle velocity, 2.5 m s-1, a peak in the metal wastage-temperature curve occurred at 350-degrees-C. However, at a particle velocity of 10 m s-1, increasing the test temperature caused a continual increase in metal wastage at an ever-increasing slope. The particle velocity-temperature effect and the mechanisms of erosion-corrosion that occurred in the low particle velocity tests are explained in terms of the surface morphologies that occurred.