Influence of the Motion Behavior on the Contact Heat Transfer Between the Covered Wall and Solid Bed in Rotary Kilns

Herz, Fabian; Mitov, Iliyan; Specht, Eckehard; Stanev, Rayko

doi:10.1080/08916152.2013.854283

Cited by 14 publications

(4 citation statements)

References 17 publications

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“…The work by Cross et al studied gaseous flame characteristics in a rotary kiln with gray radiative properties in a one-dimensional flame model, and they found that the model accurately predicted flame temperatures and radiative intensities. The convective heat transfer from the hot gas to the bed material and inner wall in an experimental kiln has been examined by Tscheng et al Conductive heat transfer has also been studied by several researchers, e.g., refs − . Wes et al concluded from experimental measurements that the conductive heat transfer between the wall of a rotary drum reactor and its bed material can be described by penetration models, that is, mathematical models to describe the heat penetration through the material.…”

Section: Introductionmentioning

confidence: 99%

Heat Transfer Conditions in Hydrogen-Fired Rotary Kilns for Iron Ore Processing

Ehlmé,

Gunnarsson,

Andersson

et al. 2023

Ind. Eng. Chem. Res.

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This work analyzes the heat transfer conditions in a rotary kiln used for the heat treatment of iron ore pellets in the grate-kiln process. The analysis concerns conditions relevant to fuel switching from coal to hydrogen gas. A modeling assessment of the radiative heat transfer in the kiln is conducted including the pellet bed and inner kiln wall temperature conditions. The results show that the heat transfer rate to the iron ore pellets under conditions of a pure hydrogen flame is comparable to the conditions relevant to coal firing. However, it is higher at the kiln wall surfaces near the burner region and lower in the remaining parts of the kiln. Increasing the particle concentration in the hydrogen flame represents a practical implication of co-firing coal with hydrogen. By adding particles, the emittance of radiation from the flame is significantly influenced, leading to further increased kiln surface temperatures closer to the burner position. Increased flame length also showed enhanced heat transfer rates to the kiln wall, although further away from the burner region.

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Section: Introductionmentioning

confidence: 99%

Heat Transfer Conditions in Hydrogen-Fired Rotary Kilns for Iron Ore Processing

Ehlmé,

Gunnarsson,

Andersson

et al. 2023

Ind. Eng. Chem. Res.

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“…Boateng and Barr [9] developed a quasi-3D model of the thermal transport in a rotary kiln by comprising a 1D axial model together with a 2D model of the rotary kiln cross-section for the bed material. Several researchers have also studied the conductive heat transfer between the wall and bed material [10][11][12][13] as well as the convective heat transfer between the freeboard and the wall and bed materials [14]. The movement of the bed material, the different modes of heat transfer as well as the impact from different parameters on heat transfer in a rotary kiln, such as the temperature dependent radiative emissivity of different materials, has been summarized by Specht [15].…”

Section: Introductionmentioning

confidence: 99%

Discrete-Ordinates Modelling of the Radiative Heat Transfer in a Pilot-Scale Rotary Kiln

et al. 2020

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This paper presents work focused on the development, evaluation and use of a 3D model for investigation of the radiative heat transfer in rotary kilns. The model applies a discrete-ordinates method to solve the radiative transfer equation considering emission, absorption and scattering of radiation by gas species and particles for cylindrical and semi-cylindrical enclosures. Modelling input data on temperature, particle distribution and gas composition in the radial, axial and angular directions are experimentally gathered in a down-scaled version of a rotary kiln. The model is tested in its capability to predict the radiative intensity and heat flux to the inner wall of the furnace and good agreement was found when compared to measurements. Including the conductive heat transfer through the furnace wall, the model also satisfactorily predicts the intermediate wall temperature. The work also includes a first study on the effect of the incident radiative heat flux to the different surfaces while adding a cold bed material. With further development of the model, it can be used to study the heat transfer in full-scale rotary kilns.

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“…Two main procedures to determine the wall-to-solid heat transfer coefficient experimentally have been reported: earlier studies [16,17,25] recorded the cooling of solids from a predetermined wall temperature, while recent investigations [18,19,20,26,27,14] mostly recorded the transient evolution of temperatures (wall, gas, and solids) during heating. The coefficient was determined through heat balances under some assumptions.…”

Section: Introductionmentioning

confidence: 99%

“…It can be noted that Malhotra and Mujumdar [35] extended the wall surface to the single particle contact heat transfer coefficient known as the first particle heat transfer coefficient to account for different particle geometries. Equation 2 has been used several times [4,20,26,27,36,37] and can be regarded as quite reliable. However, as shown by [20,14,38], there were often quantitatively significant differences between the models' predictions.…”

Section: Introductionmentioning

confidence: 99%

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

Njeng

Vitu

Clausse

et al. 2018

Experimental Thermal and Fluid Science

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A series of experiments were carried out on an indirectly heated pilot scale rotary kiln. These experiments aimed at recording, while the solids flow, the temperature profiles of the freeboard gas, the solid particle bulk and the wall, as well as the power supplied for heating, over a range of operating conditions. Based on these data, the experimental wall-to-solid heat transfer coefficient was determined through an energy balance. The effects of operating conditions, namely rotational speed, filling degree, lifter shape and controlled temperature, on the heat transfer coefficient are discussed. A model based on dimensional analysis is proposed to calculate the wall-to-solid heat transfer coefficient for low to medium heating temperatures (100-500°C). The experimental and calculated results are in good agreement. The experimental results are also compared to the predictions of some existing models. While the predictions are within a reasonable order of magnitude with regard to the experimental results, these models fail to represent actual variations with operating conditions satisfactorily rotary kiln; heat transfer coefficient; wall-to-solid heat transfer; dimensional analysis; lifter; bed depth profile

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Influence of the Motion Behavior on the Contact Heat Transfer Between the Covered Wall and Solid Bed in Rotary Kilns

Cited by 14 publications

References 17 publications

Heat Transfer Conditions in Hydrogen-Fired Rotary Kilns for Iron Ore Processing

Heat Transfer Conditions in Hydrogen-Fired Rotary Kilns for Iron Ore Processing

Discrete-Ordinates Modelling of the Radiative Heat Transfer in a Pilot-Scale Rotary Kiln

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

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