Heat and Mass Transfer in Urea Prilling Process

Urea prills are produced in the prilling tower, where a cooling-solidification-cooling process of the prills takes place. The ambient air is used as the cooling stream for this process. A case study of the urea prilling process is chosen due to in hot/humid days, the temperature of the product at the bottom of the prilling tower is hot and cannot be packed directly. In addition, the urea prills form lumps and cakes with each other on the scrubber at the bottom of the prilling tower that affects the quality of the product. A mathematical model based on the particle kinematics,and, heat and mass transfer between the urea prills and the cooling air is developed. This is followed by using a numerical technique with an explicit scheme to solve the model. The model numerical results are validated with Scanning Electronic Microscope (SEM) observation of urea particles. Moreover,to investigate the effect of the urea prilling tower configuration parameters on the above urea product problems, the hydrodynamic of air flow inside the tower is analyzed using Computational Fluid Dynamics (CFD) simulation software.