A hydrodynamic model for flighted rotary kilns used for the conversion of cohesive uranium powders

Abstract

The axial and transverse solid distribution of a cohesive powder in flighted rotary kilns was calculated from an original method based on the lifter discharge law previously determined, geometrical calculations and supplementary measurements (in particular the fall velocity of the powder at high temperature). At a given axial position, the quantity of powder falling through the gas, the total quantity of flighted powder as well as the quantity remaining in the bulk are thus calculated; the axial bed depth profile is obtained from the Saeman-Kramers-Afacan model. Highlights ► Transverse flow of cohesive powder in flighted rotary kiln was modelled. ► Axial bed depth profile was calculated from Saeman-Kramers-Afacan model. ► Solid distribution was calculated from geometrical calculations and measurements. ► The fall velocity of the cohesive powder was measured at high temperature. ► The 'snapshot' obtained allows to calculate thermal transfer areas and mass transfer.

Rotary kiln process: An overview of physical mechanisms, models and applications

“…Davies et al [30], Granados et al [31] and Liu and Specht [32] also presented a relationship to allow estimating bed height along the kiln (Table 1). The correlations proposed in [23,[33][34][35] have been derived from those in [26,36,37]. Knowledge of the bed height thus makes it possible to calculate the degree of filling of the kiln, by means of Equation (2) [25]:…”

Wall-to-solid heat transfer coefficient in flighted rotary kilns: Experimental determination and modeling

“…It consists of a feeding system, a rotating tube surrounded by a heating system and followed by a recovery zone, in accordance with the layout presented in Figure 1. Figure 1: Layout of the experimental apparatus: (1) feed hopper, (2) screw feeder, (3) feed chute, (4) kiln tube, (5) heating system: zones 1 and 2, (6) external thermocouples, (7) measuring rod with thermocouples, (8) storage tank.…”

“…They are usually designed for applications needing tight control and clean heating of materials. Possible applications include [1]: calcination [2,3,4], reduction [5,6], controlled oxidation, carburization, solid-state reaction [7,8], drying [9,10] or waste disposal [11,12]. When operated at atmospheric pressure, these units consist of a cylindrical shell that can be slightly inclined, into which the solid burden is fed continuously at one end and discharged at the other.…”

Modeling study of oil shale pyrolysis in rotary drum reactor by solid heat carrier

“…Within the last decade, many studies have been carried out, which use multi-scale modeling of heat and mass transfer processes in various types of rotary reactors [11][12][13][14]. In this work, the comprehensive multiscale numerical analysis of physical and chemical processes in the rotary reactor was performed as applied to oil shale thermal decomposition in the pyrolysis reactor of the UTT unit.…”