A design methodology was developed for prilling towers based on simultaneous heat, mass, and momentum balances. Basic principles of the prilling process and related sub‐models were considered for production of relatively mono‐size prills. The method was employed in the design of a prilling tower for production of ammonium nitrate prills from a highly concentrated solution. A special showerhead spray, operating under laminar conditions in a Rayleigh jet break‐up regime, was designed to enhance production of mono‐size prills. Air was used at ambient conditions. The droplets leaving the showerhead fall through the air stream in a counter‐current fashion. Heat transfer from particles to air includes cooling in the fully liquid state, solidification, and cooling in the fully solid state. The Computational Fluid Dynamics (CFD) simulation revealed the formation of a quiescent zone around the nozzle discharge region, which had a significant effect on decreasing the secondary disintegration of the droplets, and hence narrowed down the size distribution towards the desired value. The size of the produced prills was larger than the predicted value due to the formation of ammonia bubbles inside the prills.

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Unsupported MoS2 catalysts were synthesized for the hydrodesulfurization (HDS) of real feed gas oil using different temperatures and pressures. Hydrothermal method was utilized to prepare by using molybdenum trioxide and sodium sulfide. The characterization of the catalyst was identified by XRD, SEM, and BET techniques. It was found that BET surface and pore volume were positively affected by pressure and temperature that could improve the activity of MoS2. Kinetic analysis showed that HDS reaction over MoS2 follow pseudo-first order kinetics. Experimental results revealed that the HDS activity of the unsupported MoS2 catalyst was better than supported CoMo/Al2O3 catalyst under the same operating conditions.