Premium
Nutrient release characteristics and coating homogeneity of biopolymer coated urea as a function of fluidized bed process variables
Author(s) -
Azeem Babar,
KuShaari KuZilati,
Man Zakaria,
Trinh Thanh H.
Publication year - 2017
Publication title -
the canadian journal of chemical engineering
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.404
H-Index - 67
eISSN - 1939-019X
pISSN - 0008-4034
DOI - 10.1002/cjce.22741
Subject(s) - coating , materials science , fluidized bed , granule (geology) , homogeneity (statistics) , fluidization , particle size , composite material , particle size distribution , chemical engineering , chromatography , chemistry , organic chemistry , mathematics , statistics , engineering
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.