investigation of mercaptan removal from Kerosene using passive mixing tools: Experimental study and CFD modeling

In this work, the role of appropriate mixing for mercaptan removal from Kerosene using caustic soda has been investigated in the pilot scale. Static mixer in different conditions has been used as a passive mixing tool to achieve proper mixing, thus high performance of mercaptan removal. Two lengths of static mixer, including 20 and 40 cm, as well as two pitches 1 and 3 mm were considered in a straight line. NaOH was injected to the Kerosene line to remove (convert it to disulfide) the mercaptan. The effects of mixer length and mixer element pitch at different flow rates of Kerosene, including 2, 18 and 30 mL/s were investigated on the mercaptan removal. The experimental results showed that the concentration of mercaptan in the pilot line outlet will decrease as the flow rates of Kerosene decrease. Also, at a fixed flow rate of Kerosene, increasing the length of the static mixer and decreasing its element pitch caused the mercaptan to decrease due to proper mixing. Computational Fluid Dynamics (CFD) modeling technique was employed to describe the experimental results, fluid flow pattern, and mixing performance. Qualitative predicted results of CFD modeling show good agreement with the experimental data.