Material characterization and inter/intra-particle validation for DEM simulation of urea coating process--颗粒学报PARTICUOLOGY

Nouh, S. A., KuShaari, K., Keong, L. K., & Samsuri, S. (2024). Material characterization and inter/intra-particle validation for DEM simulation of urea coating process. Particuology, 88, 32-48. https://doi.org/10.1016/j.partic.2023.09.010

Material characterization and inter/intra-particle validation for DEM simulation of urea coating process

Salma A. Nouh, KuZilati KuShaari ^*, Lau Kok Keong, Shafirah Samsuri

Chemical Engineering Department, Universiti Teknologi PETRONAS, 32610 Seri Iskandar, Perak Darul Ridzuan, Malaysia

10.1016/j.partic.2023.09.010

Volume 88, May 2024, Pages 32-48

Received 7 July 2023, Revised 11 September 2023, Accepted 12 September 2023, Available online 9 October 2023, Version of Record 4 November 2023.

E-mail: kuzilati_kushaari@utp.edu.my

Highlights

• Experimentally characterized parameters used as input in DEM simulation provide reliable predictions in CoV_inter/intra.

• Implementation of the DDM approach in DEM coating simulation proved well for quantitative prediction of coating uniformity.

• Bulk CoV_intra of coating thickness is accurately verified using the “Averaging Moments” model.

• Inter and intra-particle CoV predictions are well compared to experimental results.

Abstract

Particle coating is a common operation in the controlled-release fertilizer (CRF) industry, where a coating layer is appliedto the urea cores. A discrete element method (DEM) computer simulation was applied to model the coating process for the urea granules using measured model parameters. The accuracy of DEM input parameters for the coating material properties and the physical and mechanical characterizations of urea granules are crucial to the study of particle coating processes. Thus, to enhance the simulation accuracy, information on the material properties (urea granules) is required. In this study, the elasticity parameters, shear modulus, coefficient of restitution (CoR), and coefficient of rolling and static friction (CoRF) and (CoSF) of urea granules are estimated experimentally in addition to the physical characteristics. The sensitivity of the angle of repose of the urea bed was investigated at different coefficients of friction. According to the obtained experimental value of the angle of repose, values of 0.2 and 0.3 for CoRF and CoSF, respectively, were adjusted to obtain consistent urea granules’ motion for simulation and the experiment. Moreover, the spray droplet sizes and velocity distributions were estimated using the video-imaging process technique. Based on this experimental characterization, elasticity parameters and spray properties were integrated into DEM simulation software as input data to perform numerical analysis of the coating process to compare simulation and experimental results, which show uniformity at three different pan speeds with a maximum deviation of 0.033 at 5 rpm. Also, consistency between DEM and experiment results was achieved in terms of average coating thickness (μm) of the selected samples and average intra-particle thickness variation (CoV_intra). These results revealed that the coating film thickness is proportional to the rotation speed for the experiment and simulation. To enhance the inter-particle coating uniformity, the effects of the most significant parameters such as pan speed, filling ratio, particle size, spray rate, and spray angle, were examined. A low spray rate, filling ratio, and high pan speed improved the coating uniformity. The particle size and spray angle show considerable influence on the coating uniformity, where larger particle sizes and spray angles tend to reduce the inter-particle coating uniformity.

Graphical abstract

Keywords

Contact model; Discrete element method; Urea fertilizer; Coating process

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