Influence of the Configuration of Feedstock Injection Nozzles on the Hydrodynamic Regime and Performance of the Catalytic Cracking Riser-Reactor for Production of Light Olefins Using CFD Modeling

The necessity of global market shift for production of light olefins influenced the catalytic cracking process in the direction of process optimization and construction modernization. This work investigated the influence of configuration (distribution) of feedstock injection nozzles on the hydrodynamic regime and performance of the riser-reactor for production of light gases (C₁–C₄). We considered eight feedstock injection nozzles in two cases. In case (a), eight nozzles are distributed in one plane around the riser-reactor, while in case (b), eight nozzles are distributed in two planes (four nozzles on each plane). Computational fluid dynamic modeling with four-lump reaction scheme with consideration of coke formation was used. Applied kinetic parameters were determined for an industrial riser-reactor with microspherical zeolite-containing catalyst. It was achieved that the distribution of solid-gas phases was enhanced for geometry (b). Mass fraction of light gases was obtained up to 0.5 (50 wt %). Moreover, the formation of coke was up to 14–15 and 9–10 wt % for geometry (a) and (b), respectively. It was observed that the main zone of chemical reactions is up to 10–15 m above the feedstock injection zone. Therefore, shortening the riser-reactor is recommended.