Study on fluidized roasting of spent hydrodesulphurisation catalysts in large-scale industrial boiling furnace by CFD simulation

When the valuable metals in the hydrodesulphurisation (HDS) catalysts are recovered by the pyrometallurgical process, the traditional roasting method is prone to the problem of insufficient oxidative conversion of metal sulfides. However, the residual oil and carbon in the spent HDS catalysts cannot be effectively utilized, resulting in additional energy consumption. Fluidized roasting in a boiling furnace is a good way to use residual oil and carbon to provide heat for roasting while oxidizing the metal sulfides in the spent HDS catalyst. This study used computational fluid dynamics (CFD) coupled with the Coarse-Graining model (CGM) to simulate the fluidized roasting effect of HDS catalysts at different initial bed heights and gas velocities in a large-scale industrial boiling furnace. To improve the fluidized roasting quality and reduce the energy consumption, it is recommended that the optimal initial bed height (H0) is 0.45 m, the gas velocity (ug) is 1.45 m/s. The gas consumption and the net energy saving were 0.34 m3/kg and 2.29 × 1010J under this condition. Accordingly, the theory of the competitive relationship between particle collision and bubble fragmentation is innovatively proposed, and the distribution change of the turbulent energy intensity zone verifies this theory.