Modeling and experimental analysis of polydispersed particles coating in spouted bed

Filho, M. Paulo; Rocha, Sandra Cristina dos Santos; Lisbôa, Antonio Carlos Luz

doi:10.1016/j.cep.2006.02.008

Cited by 24 publications

(7 citation statements)

References 5 publications

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“…This agreed with findings by da Rosa et al who also reported that a high spray rate with a low gas temperature caused lower coating efficiency due to attrition from spray loss on the fluidized bed wall. However, this result contradicted findings by Filho et al who suggested that lowest gas temperature and highest spray rate optimized conditions for higher coating efficiency. The p ‐values for fluidizing gas temperature and response surface contour indicated that gas temperature held more influence than spray rate in this particular case.…”

Section: Resultscontrasting

confidence: 80%

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Nutrient release characteristics and coating homogeneity of biopolymer coated urea as a function of fluidized bed process variables

et al. 2016

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The present study investigates the effect of fluid‐bed process parameters on the diffusion coefficient of nitrogen release and coating homogeneity of controlled‐release urea (CRU) produced in a rotary fluidized bed using polyvinyl‐alcohol‐modified starch as a coating material. An existing mathematical model was used to estimate the diffusion coefficient. The coefficient of variance of size distribution and coating mass variation are reported as a measure of coating homogeneity. Statistical analysis suggested that the most influential process variables that govern urea release characteristics and coating homogeneity were (a) fluidizing gas temperature and (b) coating time. A moderate spray rate combined with longer coating time yielded the lowest diffusion coefficient for nutrient release. Elutriation as the result of elevated fluidizing gas temperature allowed a higher diffusion coefficient due to lower coating thickness. Burst release patterns were observed for granules with coating imperfections. The augmented temperature of fluidizing gas had a negative effect on coating mass and size distribution of CRU granules but the influence of longer coating time was positive.

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Section: Resultscontrasting

confidence: 80%

“…The authors followed methods described by Abe et al, Dewettinck et al, and Filho et al to estimate the coating's mass variation. Approximately 2.0 g (±0.001 g) of equally‐sized coated granules from each sample run were immersed in distilled water until urea dissolution was complete.…”

Section: Methodsmentioning

confidence: 99%

Nutrient release characteristics and coating homogeneity of biopolymer coated urea as a function of fluidized bed process variables

et al. 2016

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“…An empirical model is presented to correlate diffusion coefficient with time for 100% release of nitrogen from SCU. The investigation of diffusion coefficients and release kinetics is imperative in designing the new controlled release fertilizers and choosing the coating material of desired controlled release characteristics [57]. The phenomenon of nutrient transport involving molecular diffusion requires the knowledge about diffusion coefficient, which is often non-constant [23].…”

Section: Empirical Modelling Of Nitrogen Release Kineticsmentioning

confidence: 99%

Production and Characterization of Controlled Release Urea Using Biopolymer and Geopolymer as Coating Materials

et al. 2020

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Synthetic polymers-based controlled release urea (CRU) leaves non-biodegradable coating shells when applied in soil. Several alternative green materials are used to produce CRU, but most of these studies have issues pertaining to nitrogen release longevity, process viability, and the ease of application of the finished product. In this study, we utilized tapioca starch, modified by polyvinyl alcohol and citric acid, as coating material to produce controlled release coated urea granules in a rotary fluidized bed equipment. Response surface methodology is employed for studying the interactive effect of process parameters on urea release characteristics. Statistical analysis indicates that the fluidizing air temperature and spray rate are the most influential among all five process parameters studied. The optimum values of fluidizing air temperature (80 • C), spray rate (0.13 mL/s), atomizing pressure (3.98 bar), process time (110 min), and spray temperature (70 • C) were evaluated by multi-objective optimization while using genetic algorithms in MATLAB ® . Urea coated by modified-starch was double coated by a geopolymer to enhance the controlled release characteristics that produced promising results with respect to the longevity of nitrogen release from the final product. This study provides leads for the design of a fluidized bed for the scaled-up production of CRU.

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“…Because of their excellent operational characteristics, including high gas–solid contact efficiency and favourable heat and mass transfer rates between gas–solid phases, as well as handling of a broad range of particle sizes, these beds are utilized in many processes such as drying, gasification, coating, granulation, and pyrolysis. [ 1–5 ] Multi‐scale models have facilitated studying the behaviour of these beds at lab and industrial scales since conducting the experimental studies on these systems is tedious and time‐consuming. Among these models, the two‐fluid model (TFM), in the Eulerian–Eulerian approach, and computational fluid dynamics coupled with the discrete element method (CFD‐DEM), in the Eulerian–Lagrangian approach, have been widely applied for simulation of gas–solid systems.…”

Section: Introductionmentioning

confidence: 99%

CFD‐DEM analysis of the spouted fluidized bed with non‐spherical particles

et al. 2021

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Hydrodynamics of spouted fluidized beds of spherical and elongated sphero‐cylindrical particles with an aspect ratio (AR) of 4 were studied by the CFD‐DEM technique. The multi‐sphere method was adopted to present the sphero‐cylindrical particles. Simulations were validated with the experimental data for both particle types. Bubble equivalent diameter, bubble shape factor, and leakage fraction were obtained in the simulations. Time‐averaged particle velocity and porosity profiles, solids circulation rate, particle exchange distribution at the spout‐annulus interface, were investigated in the beds filled with spherical and sphero‐cylindrical particles at gas mass flow rates of 0.005, 0.007, and 0.009 kg/s. The equivalent bubble diameter was found to be lower for spherical particles compared to sphero‐cylindrical particles. The leakage fraction of the bubble was lower for sphero‐cylindrical particles. Solid circulation rate and spout diameter were larger for the bed of spherical particles. A higher probability of particles transition into the spout was observed for spherical particles. Investigating the orientation showed that sphero‐cylindrical particles tend to orient almost vertically against the gas flow in the spout region, which lowers the exerted drag force, whereas the particles align nearly horizontally in the annulus region. The results revealed that the CFD‐DEM approach is a promising method for investigating the fluid and both spherical and non‐spherical particle behaviours in spouted fluidized beds.

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Modeling and experimental analysis of polydispersed particles coating in spouted bed

Cited by 24 publications

References 5 publications

Nutrient release characteristics and coating homogeneity of biopolymer coated urea as a function of fluidized bed process variables

Nutrient release characteristics and coating homogeneity of biopolymer coated urea as a function of fluidized bed process variables

Production and Characterization of Controlled Release Urea Using Biopolymer and Geopolymer as Coating Materials

CFD‐DEM analysis of the spouted fluidized bed with non‐spherical particles

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