CFD Modeling for Optimizing the Fluid Dynamics Patterns of Refractory Lining Drying Process in a Vertical Lime Kiln

Abstract

This paper presents a 3D Computational Fluid Dynamics (CFD) modeling of flow, combustion and heat transfer processes into an internal enclosure acting as a combustion chamber, confined by the newly patented air cooled “corner ring”, the lower shaft vertical side walls, the vault and the limestone packed bed, located in a vertical twin-shaft regenerative lime kiln. The numerical simulation is restricted only to the kiln first start-up preliminary phase, with the goal to optimize the thermo-fluid dynamics patterns established during the first heat-up of wet gunning refractory concrete lining of the air cooled “corner ring”, to avoid refractory damages. The present work is performed in the frame of the commercial general-purpose code ANSYS-CFX R14.5. The CFD model is run under transient flow conditions accomplished by the drying burners operated in single-stage “on-off” control mode, to fit at the best the heat-up curve by optimization of the fluid dynamics patterns, with the goal to prevent local hot spots on the refractory lining. The industrial data collected through the supervision system and the local provisional instrumentation on the vertical twin-shaft regenerative lime kiln, model RD15, commissioned in India on September last year, are used to set the test-case and to partially validate the numerical simulation results. This CFD numerical simulation represents an useful engineering tool, on behalf of refractory designer and commissioning engineer, for the prediction of the refractory lining behavior during the kiln first start-up.