FCC riser unit operated in the heat-transfer mode: Kinetic modeling

A pilot-plant unit, namely, Multicrackex, for the catalytic cracking of hydrocarbons with the riser and regenerator units under direct heat exchange conditions was developed in the course of the present study. A two-levels pseudofactorial experimental program was designed using the synthetic gas oil SF-135 (CANMET) and a commercial equilibrium catalyst (Akzo Octaboost). Using the experimental temperature profile inside the riser, the reaction rate constants and activation energies were evaluated for the four lump model. These parameters were precisely estimated (+/-7% average), and the adequacy of the model was tested by statistical analysis, showing model predictions inside the +/-15-20% error range. The experimental results and model predictions indicate that endothermic effects of the cracking reactions and gas oil vaporization are neutralized by the heat transfer from the regenerator to the riser.