CFD Modelling of Air Injection Nozzles in Coke Calcination Kilns, Identification of the Best Compromise Between Carbonaceous Deposit Formation and Kiln Performance

Rio Tinto operates three cokeCoke calcinationCalcination plants in Canada. The kilnsKiln differ not only in size and production capacity but also in the design of the nozzles for third air injection. At one site (calciner A) especially, carbonaceous depositsDeposits form on the surfaceSurface of kilnKiln refractoriesComputational fluid dynamics. Computational Fluid Dynamics (CFD)Computational Fluid Dynamics (CFD) was used to simulate the impact of different nozzle designs on depositDeposits formationFormation. It was shown for calciner A that the design of the nozzles contributes to higher gas velocities and strong vortex. These conditions favour the entrainment of fine cokeCoke particles, thought to be the origin of depositDeposits formationFormation. The simulationSimulation showed that entrainment could be reduced by a nozzle redesign similar to the other two sites. However, any redesign would be accompanied by a lower cokeCoke temperature in the calcinationCalcination zone and thus a poorer process performance. The simulationSimulation was used to identify the best compromise between depositDeposits formationFormation and kilnKiln performance.