Transverse flow at the flight surface in flighted rotary drum

Sunkara, Koteswara Rao; Herz, Fabian; Specht, Eckehard; Mellmann, Jochen

doi:10.1016/j.powtec.2015.01.058

Cited by 13 publications

(2 citation statements)

References 22 publications

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“…It is often used for drying, granulation, calcining, and coating [3]. Rotary drum dryers are often equipped with internal flights to lift the material to form a material curtain [4,5] and increase the contact area between the material [6,7]. The flight divides the drum into an active phase and a passive phase [8].…”

Section: Introductionmentioning

confidence: 99%

DEM Simulation of a Rotary Drum with Inclined Flights Using the Response Surface Methodology

Zhu

Xie

et al. 2023

Processes

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Conventional flighted rotary drums usually have flights parallel to the rotating axis, which cannot facilitate the axial motion of the materials in the drum. Here, a new type of horizontal rotary drum with inclined flights and beads was designed. Inclined flights are used to facilitate the axial movement of beads and material, while beads are used as fillers to increase the gas-liquid contact area and to crush the solid materials. We simulated the drum and studied the axial motion of fillers using the discrete element method (DEM). To improve the mass and heat transfer performance, we optimized the distribution of beads in the active phase. The effects of the rotational speed, joint angle, and inlet flow rate in the drum were investigated systematically. The individual effects were evaluated in terms of the mass of particles in the active phase (MAP) and passive phase (MPP), the percentage of the active phase occupied by the particles (OAR), and the axial speed (AS). The response surface methodology (RSM) was used to investigate the significant effects of the interaction between the parameters. The maximum MAP value can be obtained by the following parameters: a rotational speed of 37 rpm, joint angle of 139°, and inlet flow rate of 7.83 kg/s. The interaction between rotational speed and inlet flow rate is the most significant for MAP. The joint angle and inlet flow rate have a significant interactive effect on AS. Besides, the rotational speed, joint angle and inlet flow rate show an interactive effect on OAR and AS. Based on the optimization results, the effect of the inclined angle on the axial motion of beads was also evaluated. The axial motion of the beads occurs mainly in the active phase. Compared to the drum without inclined flights, the drum with inclined flights has an enhanced axial speed increased by 26%. This study will be helpful for the design and optimization of drums with inclined flights.

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Section: Introductionmentioning

confidence: 99%

DEM Simulation of a Rotary Drum with Inclined Flights Using the Response Surface Methodology

Zhu

Xie

et al. 2023

Processes

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“…It is clear that with the baffles, the frequency of collision increases and the mixture efficiency of flexible particles improves. Therefore, baffles were of significance to the transport behaviors of these flexible biomass particles in order to improve the mix efficiency of cylindrical tube processes. − Normally, dense and dilute phases existed in the rotating cylindrical tube, as shown in Figure . , A number of particles were accumulated at the bottom of the tube, contacted, and moved with the migration of the inner wall and baffles. In this case, the accumulation zone could be named the dense phase.…”

Section: Introductionmentioning

confidence: 99%

Visual Experimental Analysis of the Residence Time of Flexible Biomass Particles in a Baffled Rotating Cylindrical Tube

Zhang

Pan

et al. 2020

Energy Fuels

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Drying of biomass or biofuels is a major issue during pretreatment because of a high initial moisture content, which results in low energy efficiency and combustion temperature and high emission of hydrocarbons. As the motion behaviors of biomass fuels play an important role in the drying process, it is of great significance to investigate the motion of biomass. In this study, visualization experiments on the motion of flexible nonspherical biomass particles in a baffled rotating cylindrical tube were performed. The residence time of biomass particles was obtained and analyzed by taking into account gas velocity, mass flow rate of flexible biomass, initial moisture content of biomass particles, slope and rotational speed of the cylindrical tube, and other parameters under several operational conditions. The results indicated that the mean residence time of flexible biomass increased with the increase in the mass flow rate and initial moisture content and decreased with the increase of the cylindrical tube’s rotational speed and slope and the velocity of the gas phase. Despite the quite small sliding friction coefficient between the tube’s inner wall and biomass particles, a larger slope could lead to stronger sliding friction force in the axial direction when these biomass particles moved to the bottom of the tube. Mean residence time is observed to decrease significantly and gradually decrease with the increase in rotational speed from 6 to 9 rpm and from 9 to 18 rpm, respectively. In addition, the mean residence time increased from 78.5 to 99.4 s when the inlet mass flow rate increased from 60 to 240 kg/h without the gas phase, but it increased from 57.4 to 78.5 s within the same range of the inlet mass flow rate at a gas velocity of 0.3 m/s.

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Modelling the final discharge angle in flighted rotary drums

et al. 2022

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Rotary drums equipped with longitudinal flights are mainly used to dry granular solids and handle high throughputs. The design of the flights is a crucial task because they decisively influence the distribution of the particles over the dryer cross section. In a previous work, the authors derived a mathematical model for the particle flow in rotary drums with rectangular flights. In this model, the final discharge angle was underpredicted resulting in errors when calculating the contact area of the particles in the air-borne phase. Therefore, a new model was developed in this study to predict the final discharge angle based on a forces balance approach on a single particle. This approach includes the Coriolis force acting on the last discharging particles sliding down the inclined flight sheet. The model was solved by using the vector analysis method. Experiments were performed at rotary drums with 0.5 m and 1.0 m in diameter, respectively, and 0.15/0.3 m in length using glass beads and quartz sand as bed materials. Each drum was equipped with 12 flights around the shell. The model validation was performed by varying the bed material, drum diameter, flight length ratio, and the rotating speed. The model predictions have shown that as the flight length ratio and the Froude number increased, the final discharge angle attained higher values. The model predictions agree well with the measurements. Graphic abstract

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Transverse flow at the flight surface in flighted rotary drum

Cited by 13 publications

References 22 publications

DEM Simulation of a Rotary Drum with Inclined Flights Using the Response Surface Methodology

DEM Simulation of a Rotary Drum with Inclined Flights Using the Response Surface Methodology

Visual Experimental Analysis of the Residence Time of Flexible Biomass Particles in a Baffled Rotating Cylindrical Tube

Modelling the final discharge angle in flighted rotary drums

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