Effect of lifter shape and operating parameters on the flow of materials in a pilot rotary kiln: Part I. Experimental RTD and axial dispersion study

Njeng, Alex Stéphane Bongo; Vitu, Stéphane; Clausse, Marc; Dirion, Jean-Louis; Debacq, Marie

doi:10.1016/j.powtec.2014.03.066

Cited by 51 publications

(32 citation statements)

References 45 publications

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“…These trends, as shown in Fig. 4, were previously discussed in detail by Bongo Njeng et al [18]. Note that only experiments with lifters are presented in Fig.…”

Section: Influence Of Operating Conditionssupporting

confidence: 81%

“…Due to their extensive use in industry, there have been several studies aimed at modeling the transport of the solids through the kiln cylinder [1][2][3][4][5][6][7][8][9][10][11][12][13], which is usually equipped with lifters [14][15][16][17]. Most of these studies attempted to understand and predict key parameters such as the hold-up, the mean residence time (MRT) or, as shown in Part I of this study [18], the residence time distribution of solid particles.…”

Section: Introductionmentioning

confidence: 99%

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Effect of lifter shape and operating parameters on the flow of materials in a pilot rotary kiln: Part II. Experimental hold-up and mean residence time modeling

et al. 2015

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International audienceExperiments were carried out on a pilot scale rotary kiln equipped with lifters at room temperature to investigate the effects of the kiln slope, rotational speed, mass flow rate of materials, and exit dam height on the hold-up and the mean residence time (MRT). The MRT was determined from the residence time distribution measurements as detailed in Part I of this work. Two granular solids having different properties were used: sand and broken rice. Furthermore, two shapes of lifters were compared to determine the influence of lifter geometry: straight lifters (SL) and rectangular lifters (RL). A new model to predict the MRT was established by means of a dimensional analysis. The correlation not only gave good agreement with the experimental data from the present study, but also demonstrated good predictive performances when applied to published experimental data of other kilns; the model is applicable for inclined kilns that process materials in cascading (tumbling) motion, whether or not equipped with lifters or fitted with dams at the outlet end

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“…These trends, as shown in Fig. 4, were previously discussed in detail by Bongo Njeng et al [18]. Note that only experiments with lifters are presented in Fig.…”

Section: Influence Of Operating Conditionssupporting

confidence: 81%

Section: Introductionmentioning

confidence: 99%

Effect of lifter shape and operating parameters on the flow of materials in a pilot rotary kiln: Part II. Experimental hold-up and mean residence time modeling

et al. 2015

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“…The lifter configurations are ranked almost into identical order using the mixing index values based on the dispersion coefficient or based on CoV from Equation (6). The axial dispersion coefficients were 14-41 cm 2 /min for the studied geometries, which are higher compared to Bongo Njeng et al (2015a) and Gao et al (2013) results possibly due to different fluid media.…”

Section: Resultscontrasting

confidence: 54%

“…The basis in the mixing research has been the residence time distribution measurement. Bongo none defined Njeng et al (2015a;2015b; determined residence time distributions for different type of solids by monitoring the outlet flow NaCl concentration in the continuous flow rotary kiln equipped with longitudinal lifters. Despite the possibility of NaCl segregation, they proposed rotary drum mixing analysis based on the calculated axial dispersion coefficients for kiln slope, dam height, and number of mixing elements in the drum.…”

Section: Introductionmentioning

confidence: 99%

A Novel Machine Vision Based Image Analysis Method for the Analysis of Mixing Elements in Rotary Drums

Koiranen

Melanen

Ilonen

et al. 2017

Chemical Engineering Communications

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Mixing performance in continuous rotary drums has been studied. The video analysis method was developed to evaluate different configurations of straight lifters in the rotary drum. The method converts a captured video into a single image, called stack image. The color marker tracking was estimated based on the color saturation of the stack image. Coefficients of variation and mixing indices were calculated from the color saturation profiles for different straight blade lifter configurations. The video analysis method was confronted to the impulse response of acid concentrations in water solutions. The developed analysis method has been superior with viscous fluids compared to traditional tracer impulse method in mixing evaluations. Water and 1% CMC-water solution were used in this mixing study for covering broadly different viscous materials. The drum lengthwise results for one lifter configuration were obtained from a single experiment due to the block representation of the image analysis method. It enables mixing analysis of axial segments and interaction analysis of mixer configurations. Thus, the axial mixing can be studied in more detail with rotary drums. The increase of lifters, residence time, and tip speed improved axial mixing in the studied experimental setup.

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“…In industry, lifter holdup and Mean Residence Time (MRT) are the main rotary dryer design parameters. [13,14] The lifter holdup represents the volume of material lifted, which is then suspended for an interval of time in the air in the form of particle curtains. The MRT is the mean time taken by the particles to pass through the tube.…”

Section: Introductionmentioning

confidence: 99%

Theoretical description of the motion of a particle in rotary dryer

et al. 2018

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This paper presents a theoretical description of a particle motion in a rotary dryer equipped with straight lifters distributed on its periphery. In this configuration, the transport of granular materials occurs with cyclic cascades that can be decomposed into three phases: lifting, discharging, and falling into the air stream. In order to describe each of these phases, we have focused on the motion of a single particle in a rotating drum. In this condition, the analytical solution of the motion equation of each phase is found. With these solutions, the position and the velocity of the particle at any time are thus expressed as a function of physical parameters of the particle, physical parameters of the drum, and physical parameters of air in the drum, called operating parameters in practice. With these equations, we are able to calculate the behaviour of the particle as a function of the operating parameters. The transposition to the industrial context is made with an application. We show how these equations particularly permit the estimation of the Mean Residence Time (MRT) of material during the drying process as a function of operating parameters. Such estimations have been validated by comparison with experimental data of MRT found in the literature. The work presented in this paper gives some useful mathematical relations for whose who are interested in drum design optimization (lifter length, drum radius, drum length, etc.). More specifically, they can be used to help with the choice of operational parameters values that would achieve a given value of MRT for particular product.

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Effect of lifter shape and operating parameters on the flow of materials in a pilot rotary kiln: Part I. Experimental RTD and axial dispersion study

Cited by 51 publications

References 45 publications

Effect of lifter shape and operating parameters on the flow of materials in a pilot rotary kiln: Part II. Experimental hold-up and mean residence time modeling

Effect of lifter shape and operating parameters on the flow of materials in a pilot rotary kiln: Part II. Experimental hold-up and mean residence time modeling

A Novel Machine Vision Based Image Analysis Method for the Analysis of Mixing Elements in Rotary Drums

Theoretical description of the motion of a particle in rotary dryer

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