The flow/mixing condition of feed oil and catalysts in the feed injection zone of FCC riser plays a crucial role in the yield of the desired products. The early relative researches were essentially tentative optimization works. In recent years

large cold model experimental research

theoretical analysis and CFD simulation were widely carried out. It was found that the feed jet secondary flow

which is generated by a Kutta-Joukowski transverse force

contributes considerably to the mixing and flow in the traditional feed injection zone. Therefore

effectively controlling and utilizing the secondary flow is the key factor to optimize the traditional feed injection scheme. The proposed improved scheme has been widely used in commercial units. In the past six years

the downward pointed feed injection scheme has been proved to be a more desired structure by the Kutta-Joukowski transverse force analysis

cold model experiment and CFD simulation. It was shown that the mixing of feed oil and catalysts was intensified while the contacting of two-phase presented more uniform. In other words

the downward pointed feed injection scheme exhibited more obvious advantages comparing with the traditional.