DEM–CFD Investigation of Packing Structure Effects on the Thermal Decomposition of Limestone

A radiation model based on the discrete ordinates method (DOM) is integrated into a discrete element method (DEM)–computational fluid dynamics (CFD) framework to simulate limestone calcination in a moving particle bed with gas flow. Local porosity of the particle bed is incorporated into the model to compute the effective radiative heat transfer for different packing densities. The endothermic calcination reaction converts CaCO 3 into CaO. The article evaluates radiation penetration, temperature distributions, calcination degree, and CO 2 mass fraction in the system. Convective, radiative, and particle–particle conductive heat transfer are considered for dilute, moderate, and dense packing densities. Results show that packing density strongly influences both radiation and calcination. The study shows that the calcination degree decreases with increasing packing density. The simulation results yield average calcination degrees of 98%, 80%, and 60% for particles at outlet in the dilute, moderate, and dense configurations, respectively.