A novel multi-probe continuous flow ultrasound assisted oxidative desulfurization reactor; experimental investigation and simulation.

In this work, a cylindrical multi-probe continuous flow system with different injection strategies was exploited to study ultrasound assisted oxidative desulfurization process. The effects of nozzle number, nozzle diameter, ultrasonic power and volumetric flow rate (residence time) on the desulfurization efficiency of the diesel fuel were investigated. It was found that the sulfur removal increases by increasing the nozzle diameter when the flow rate is fixed. Sulfur removal was increased by increasing the residence time, for all types of the nozzles. Injection of the aqueous phase below the horn tip in the active zone provides the conditions by which the higher interfacial area between the phases and thus greater conversion rate can be obtained. The results indicated that over 97% sulfur removal was achieved using the double-nozzle injection with nozzle diameter of 1.5 mm, residence time of 15 min, electrical power of 277.2 W and volumetric flow rates of the aqueous and oil phases 48.89 and 244.44 mL/min, respectively. The simulation results showed that choosing a proper injection strategy has an impact on the hydrodynamic and flow pattern induced by ultrasonic field and in turn could effectively influence the mixing of the two-immiscible phases. A more uniform distribution of the aqueous-phase volume fraction was observed in the system with double-nozzle injection in comparison with the single nozzle injection.