Experimental Apparatus for Studying Heat Transfer in Externally Heated Rotary Kilns

Abstract

Rotary kilns are widely used in several branches of the chemical industry. In order to control the temperature of the solid and the gas flowing through the kiln, it is important to understand the heat exchange phenomena that occur. The design and construction of a novel experimental device to study heat exchange in rotary kilns is described. The device, which comprises a rotary kiln equipped with an external electrical heating system, enables the study of the influence of various parameters such as the solid flow rate, the kiln inclination angle, the rotational speed, or the presence of lifters on heat exchange and in particular on the heat exchange coefficient between the solid and the wall. Preliminary experimental results concerning the influence of the solid flow rate and the rotational speed on the solid-to-wall heat exchange coefficient are presented.

Measurement of residence time distribution in a rotary calciner

“…Similar experimental results were observed in the study of a novel experimental apparatus for temperature measurements. 18 It was found that the solid-to wall heat-transfer coefficient increases linearly with the solid flow rate but shows negligible variation with the rotary speed. A new 3-D temperature measurement system consisting of thermocouple arrays was Correspondence concerning this article should be addressed to F. J. Muzzio at fjmuzzio@yahoo.com.…”

Prediction of conductive heating time scales of particles in a rotary drum

“…Some attention has been given to the heat transfer mechanisms in these systems through experiments (Liu and Specht, 2010;Thammavong et al, 2011;Wes et al, 1976), continuum modeling (Boateng and Barr, 1996;Dhanjal et al, 2004), DEM modeling (Chaudhuri et al, 2006;Figueroa et al, 2010;Gui et al, 2013;Nguyen et al, 2014;Schmidt and Nikrityuk, 2011;Shi et al, 2008), a comparison of both types of modeling (Kwapinska et al, 2008), or a combination of modeling and experiments (Chaudhuri et al, 2010;Kwapinska et al, 2006). Although continuum models generally match experimental trends, DEM provides new information about individual particle behavior (e.g., temperature distributions), which can aid in understanding the link from single particle to bulk particle bed behavior.…”

“…In our system, we only consider contact conduction between the heated drum walls and the particle bed, and between particles. Contact conduction is expected to dominate in operations where the fluid phase is stationary and its thermal conductivity is small, and where temperatures are moderate (o 500°C) (Chaudhuri et al, 2010;Schmidt and Nikrityuk, 2011;Thammavong et al, 2011). Although conduction-only heat transfer may be a simplification of the heating occurring in real systems, it is essential to focus first on understanding the governing phenomena involved in this primary heat transfer mode before further complexities are added.…”

“…In experiments, bed temperature at different locations can be monitored with thermocouples, but it is not possible to track each particle's temperature. The results generally include the determination of heat transfer coefficients that are valid under the specific set of conditions studied (Thammavong et al, 2011). Thus, discrete computational simulations are a useful way to study heat transfer in rotary drums due to the ability to investigate the effects of various operating parameters and material properties, and to track each particle's temperature.…”

Convective heat transfer analysis in aggregates rotary drum reactor

“…Important points were focused upon the interfacial heat transfer phenomena inside particulates rotary kiln. Thammavong et al [4] described the many experimental results existing in the literature dedicated to the evaluation of the gas/wall transfer coefficient, h gw , and the solid/wall transfer, h sw . Based on the penetration model, many equations have been identified in order to predict solid/wall transfer coefficient in rotary kiln in laboratory tumbler with sand materials.…”