Novel design and modeling of a coupled high-density downer-riser reactor

A novel design of a coupled high-density downer-riser reactor is proposed and demonstrated feasible operation at high flux conditions in a pilot-scale experimental setup. This coupled reactor aims to utilize both downer and riser advantages to improve the gasoline quality and efficiently control the distribution of FCC products. Downer accommodates high severity cracking reactions at the initial stage with the benefit of plug flow operation; while riser is operated at a low temperature with longer contacting time to promote hydrogen shift reactions. A 2D dispersion model incorporated with riser/downer hydrodynamics and an 11-lump FCC kinetics model is established to validate the conceptual design. Promising results are achieved for the coupled downer-riser reactor compared with a conventional riser.