Experimental study on influence of blade angle and particle size on particle mechanics on a batch-operated single floor of a multiple hearth furnace--颗粒学报PARTICUOLOGY

Kriegeskorte, M., Hilse, N., Spatz, P., & Scherer, V. (2024). Experimental study on influence of blade angle and particle size on particle mechanics on a batch-operated single floor of a multiple hearth furnace. Particuology, 85, 224-240. https://doi.org/10.1016/j.partic.2023.06.009

Experimental study on influence of blade angle and particle size on particle mechanics on a batch-operated single floor of a multiple hearth furnace

Max Kriegeskorte ^*, Nikoline Hilse, Phil Spatz, Viktor Scherer

Institute for Energy Plant Technology (LEAT), Ruhr University Bochum, Universitätsstraße 150, 44780 Bochum, Germany

10.1016/j.partic.2023.06.009

Volume 85, February 2024, Pages 224-240

Received 7 February 2023, Revised 1 June 2023, Accepted 9 June 2023, Available online 28 June 2023, Version of Record 7 July 2023.

E-mail: kriegeskorte@leat.rub.de

Highlights

• An increase of particle free surface area indicates enhanced heap formation.

• Frequency distribution of distance among particles is a measure for spatial arrangement of particles.

• Blade inclination increases particle free surface area.

• Particle free surface area is a non-monotonous function of particle size.

• Frequency distribution of the distance among particles is typically bimodal.

Abstract

In industry, multiple hearth furnaces are used for the thermal treatment of particulate material. The current contribution concentrates on the experimental analysis of particle mechanics for a batch-operated single floor of a multiple hearth furnace. The particles are agitated on the circular floor by a single, rotating rabble arm equipped with three flat rabble blades of 10 mm thickness. The blade angle, defined as the angle, which the blade is inclined against the tangential direction, is varied from 0° to 90°. A single layer of spherical polyoxymethylene (POM) particles with three different diameters (5, 10 and 20 mm) is placed on the floor. To analyze the results, two parameters have been extracted from image analysis when the bed of particles is agitated, first, the area not covered by particles and second, the frequency distribution of the mean distance among the particles. The particle free surface area increases with the inclination of the blades. The evolution of the particle free surface area differs for the different particle diameters. In general, the maximum particle free area for all blade angles is the largest for the 5 mm particles followed by the 20 mm particles. For the 10 mm particles, the particle free surface area starts for a blade angle of 0° at larger values than for the 20 mm particles but the values fall below the values for the 20 mm particles for larger blade angles. The reason for this behavior is discussed in detail. The mean distance among the particles is a parameter characterizing the length scales dominating the effects on the floor. The frequency distribution of the mean distance among particles provides information about the morphology of the particle bulk, for example, whether the free surface area is interspersed with particles.

Graphical abstract

Keywords

Hearth furnace floor; Particle movement; Spherical particles; Particle free surface area; Mean distance among particles

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