Ultrathin coating of particles in fluidized bed using submicron droplet aerosol--颗粒学报PARTICUOLOGY

Mezhericher, M., Rieck, C., Razorenov, N., & Tsotsas, E. (2020). Ultrathin coating of particles in fluidized bed using submicron droplet aerosol. Particuology, 53, 23-29. https://doi.org/10.1016/j.partic.2020.03.005

Ultrathin coating of particles in fluidized bed using submicron droplet aerosol

Maksim Mezhericher ^{a 1}, Christian Rieck ^{b 1 *}, Nikolay Razorenov ^c, Evangelos Tsotsas ^b

a Mechanical and Aerospace Engineering, Princeton University, Princeton, NJ 08544, USA
b Thermal Process Engineering, Otto-von-Guericke University, 39106 Magdeburg, Germany
c Mechanical Engineering, Shamoon College of Engineering, Beer Sheva, 84100, Israel

10.1016/j.partic.2020.03.005

Volume 53, December 2020, Pages 23-29

Received 26 November 2019, Revised 27 March 2020, Accepted 30 March 2020, Available online 23 May 2020, Version of Record 16 December 2020.

E-mail: christian.rieck@ovgu.de

Highlights

• Presentation of ultrathin particle coating in a proof-of-principle experiment.

• Particles were coated in a lab-scale fluidized bed with a novel aerosol generator.

• The process is shown to be feasible with an improvable yield in the range of 30%.

• Monte Carlo simulations indicate reduced processing times and material need.

• Application may be scalable and affordable production of high-resolution coatings.

Abstract

In this work, we demonstrate that particles can be coated in a fluidized bed with coating solution provided by a novel aerosol generator. Aerosol droplets are smaller than 1 μm in volume-based diameter, hence they are very much smaller than droplets in conventional spray fluidized bed processes (around 40 μm). A proof-of-principle experiment with 30% aqueous coating solution of sodium benzoate and γ-Al₂O₃ core particles in 150 mm fluidized bed fed with droplet aerosol supplied from the chamber side is presented. To simultaneously coat and dry the particles, inlet of fluidization air was at 50 °C. Moreover, Monte Carlo simulations of coating with small aerosol and large spray droplets were conducted. Due to dramatically smaller building blocks, ultrathin particle coating of high-resolution (very small layer thickness) can be attained with the new aerosol process, with the potential of even going nanoscale. Full coverage of particles is reached substantially faster than in the conventional process, so that material demand is much lower and sensitive materials can be processed in short residence time. Solids yield of around 30% was much higher than expected, that is considered to be technically viable and may be enhanced by the recycling of entrained solids or better equipment design.

Graphical abstract

Keywords

Aerosol; Fluidized bed; Particle; Submicron droplet; Ultrathin coating

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