Review on erosion of horizontal tubes immersed in fluidized beds of Geldart B particles

The erosion of internals is a major problem in fluidized beds. This review collects, discusses, and compares key experimental and numerical results on erosion of internals immersed in fluidized bed with Geldart B (sometimes near D) particles, comparing the different models and experimental data available in the literature. The erosion models were classified into two categories, depending on the nature of the considered variables. Microscopic erosion models that use particle-scale variables, such as the velocity of the impinging particle or local void fraction; and macroscopic erosion models, which rely on macroscopic features of the fluidized bed, such as air flow rate, bubble size and distribution or height above the distributor. This study of different erosion models reveals noteworthy differences. In the case of macroscopic models, since they include empirical constants, the erosion rates predicted by different models reveal differences of three orders of magnitude (between 0.001 and 1 micrometres per hour). Similar differences are observed with the microscopic models at the point of maximum erosion, located at the sides of the tube. The experimental data, despite not being directly comparable due to the different experimental conditions and materials, show a similar erosion profile along the perimeter of the tube with an inverted W-shape.