The present work addresses a fundamental study on flighted rotary kilns. They are gas-solid reactors, used in a variety of industries to process heterogeneous media. However, operating these kilns mainly relies on the know-how of operators due to insufficient fundamental understanding. The aim of this work is to provide engineers with relevant tools and models to assist in the design stage and the performance improvement of existing operating process units, in particular indirectly heated rotary kilns, inclined and equipped with lifters. In the first part, we studied the effects of operating parameters on the flow of materials of differing properties and shape. For this purpose, residence time distribution measurements were performed through experimental stimulus response tests. Two pilot-scale rotary kilns with similar length-to-diameter ratios, but a dimension ratio of about two were used in this study. We focused on the effects of lifter shape and configurations. The effects of the rotational speed, the kiln slope, the mass flow rate and the exit dam height were also analyzed. The flow of solids was quantitatively characterized primarily by the experimental mean residence time, hold-up, and axial dispersion coefficient. Using a dimensional analysis, models were established to predict the mean residence time, the filling degree and the axial dispersion coefficient, providing basic information on the kiln design, solid particle properties and operating conditions. In the second part, we studied the heat transfer mechanisms occurring in the flighted rotary kiln by measuring temperature profiles at the wall, the freeboard gas and the bulk of solids. Analysis of the temperature profiles focused on two main issues: assessment of the heat transfer coefficient between wall and gas, and assessment of the heat transfer coefficient between wall and solid particles. The lumped system analysis and a heat balance using the power supplied for the heating were applied to determine the experimental heat transfer coefficients. The effects of operating conditions and lifting flights were analyzed. Both heat transfer coefficients were then correlated through dimensional considerations. Lastly a global dynamic model mainly based on the models developed in this study can be used to determine wall, gas and bulk solids axial temperature profiles in an indirectly heated flighted rotary kiln. This global model needs to be completed with specific models related to a reaction so as to be used as a framework for the simulation of specific industrial rotary kilns.

Two types of inert sand feed were used, fine sand (FS) and coarse sand (CS). The aim of the tests with the concentrate feeds was to determine the effects of varying the firing rate, feed rate and rotation rate on the overall heat transfer and the decomposition of the concentrate feeds. The aim of the tests with the inert feed was to determine the effects of varying the rotation rate, fraction of fill and solids particle size on heat transfer. Predictions from the heat transfer model were compared to experimental data from the tests with the CS feed type and experimental data obtained from the literature.

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Rotary Kilns—rotating industrial drying ovens—are used for a wide variety of applications including processing raw minerals and feedstocks as well as heat-treating hazardous wastes. They are particularly critical in the manufacture of Portland cement. Their design and operation is critical to their efficient usage, which if done incorrectly can result in improperly treated materials and excessive, high fuel costs. This professional reference book will be the first comprehensive book in many years that treats all engineering aspects of rotary kilns, including a thorough grounding in the thermal and fluid principles involved in their operation, as well as how to properly design an engineering process that uses rotary kilns. This new edition contains an updated CFD section with inclusion of recent case studies and in line with recent developments covers pyrolysis processes, torrefaction of biomass, application of rotary kilns in C02 capture and information on using rotary kilns as incinerators for hydrocarbons. Provides essential information on fluid flow, granular flow, mixing and segregation, and aerodynamics during turbulent mixing and recirculation Gives guidance on which fuels to choose, including options such as natural gas versus coal-fired rotary kilns Covers principles of combustion and flame control, heat transfer and heating and material balances New edition contains information on pyrolysis processes with low temperatures and torrefaction of biomass. It also covers calcination of petcoke, how rotary kilns are used as incinerators for chlorinated hydrocarbons. Includes updated material on CFD simulation of kiln gas and solids flow with a selection of recent case studies.