CFD Modelling of Calcination in a Rotary Lime Kiln

A 2D axisymmetric computational fluid dynamics (CFD) model, coupled to a 1D bed model, has been developed to capture the key processes that occur within rotary lime kilns. The model simulates the calcination reaction using a shrinking core model, and predicts the start of calcination and the degree of calcination at the end of the kiln. The model simulates heat transfer due to radiation, convection and conduction between the gas, wall, chains, and bed. The 2D gas and 1D bed models are coupled by mass and heat sinks to simulate heat transfer, evaporation, and the calcination reaction. The model is used to simulate two industrial kilns, one wet and one dry. The steady-state simulation results are compared to mill data, and good agreement is found. A sensitivity analysis is also presented, to obtain insight on how operating conditions and model variables impact the calcination location and degree of calcination.