Rotary kilns are commonly used to destroy waste materials (incineration) or to create new materials (materials processing). Materials processing applications in rotary kilns include cement calcining, trona calcining, phosphate ore nodulizing, soda ash bleaching, laterite ore reduction, petcoke calcining, and lime sludge calcining. Reaction Engineering International has developed a propriety CFD code, GLACIER, which has been used to model rotary kiln systems in a number of different materials processing fields. For the rotary kiln application, a submodel for the solid bed material has been coupled to the gaseous flow in GLACIER. The solid bed material is tracked along the length of the kiln; kinetics of reactions in the bed (e.g., calcinations) are included in the solid bed model and an energy balance is performed along the length of the kiln to determine the temperature and composition of bed material. Each application requires a different set of thermodynamics and kinetics, specific to the material being processed. REI has developed and tested a variety of heat and mass transfer submodels, including: angle of repose, shell-bed heat exchange, dust radiative heat transfer, lifters/particle showering, and chain heat transfer. The results of applying this unique CFD model to rotary kilns in a number of different pyro-processing applications will be presented in this paper and comparisons made between the predictions and field experience. Areas of emphasis have included process product quality optimization, kiln temperature control, Nox and CO pollutant emissions, fuel switching, fuel efficiency, and kiln equipment optimization.
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