The influence of test parameters on material wastage in a fluidized bed wear test rig

Abstract

The characteristics of metal wastage of in-bed heat exchanger tubes are an important problem in the development of fluidized bed combustors. A unique laboratory-scale fluid bed wear tester apparatus was operated at room temperature to study the behavior of aluminum rod-shaped specimens exposed to fluidized erodent particle beds having different ratios of SiO 2 to bed material from operating bubbling fluidized bed combustors (BFBCs). The mass and circumferential thickness change distributions of the specimen rods were measured. Only part of the specimen surface was worn, while a deposited layer of bed particles and aluminum was formed on other regions of the cylinder surface that prevented metal wastage. The morphologies and compositions of the deposit layer on several specimen rods were measured. It was determined that the SiO 2 constituent in the bed material particles caused the metal wastage, while the calcium compounds in the BFBC bed material contributed to the formation of the deposit layers. The more SiO 2 in the bed particles, the more metal wastage occurred. The larger the particle size was, the greater was the metal wastage. Direct metallographic evidence was found that both particle impact erosion and three-body abrasive wear metal wastage mechanisms occurred.