CFD Modelling of Calcination in a Rotary Lime Kiln

Abstract

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.

Application of Flexible Tools in Magnesia Sector: The Case of Grecian Magnesite

“…In Figure 14, there is a comparison of the base case with different substitution rates (SR) using PSD or OK. The maximum temperature reached with coke is above 1700 • C which is in agreement with measurements and simulations by other authors [27][28][29][30][31][32]36]. When coke is partially replaced with biomass, there is a decrease in the average temperature that is more pronounced the higher the substitution rate is.…”

“…As discussed above, the approach to solve the equations is the standard RANS which separates the average flow from the turbulent scales. The turbulence model chosen is the standard κ-ε [32,[34][35][36] with non-equilibrium wall functions. Wall functions allow a faithful representation of the flow close to a wall without the need for a thin mesh, which would slow down calculations.…”

“…The CFD simulation of combustion considers several processes especially for rotary kilns [26][27][28][29][30][31][32][33][34][35][36]. The chemical reactions in the gas phase comprise hundreds of species and chemical reactions.…”

Industrial Rotary Kiln Burner Performance with 3D CFD Modeling

“…It is well established that an industrial burner of a cement rotary kiln has different entries to receive primary and alternative fuels in different states of matter [14][15][16][17]. Additionally, to achieve self-sustained combustion, different air mass flows must be supplied (commonly primary and preheated secondary air) [15,16]. Based on the information provided above, it is realizable that modeling is usually performed by simplifying the geometry of the burner or the mixture of fuels.…”