Novel Designs and Simulations of FCC Riser Regeneration

Two novel designs of FCC riser regeneration are proposed in this work. To improve the regeneration performance of a single riser regenerator, the first design allows the regenerating air to be separately supplied at several different levels in the riser. Simulations based on the riser regeneration model previously developed by us show that this method provides good operation performance with improved flexibility and stability, higher solids inventory, and longer solids residence time. By properly adjusting the air flow rates and the regenerated catalyst recycle ratio, this multiple air supply riser regenerator can meet the specifications of most industrial units: reducing the carbon content on the regenerated catalyst to less than 0.1 wt % and controlling the riser temperature under 730°C. The second design is a two-stage riser FCC regenerator, which connects two riser regenerators in series. This novel design combines the advantages of both the riser regeneration and the conventional two-stage turbulent bed regeneration. It also provides significant advantages over the single riser regenerator: operating the second riser at high temperature without catalyst hydrothermal deactivation and greatly increased regeneration efficiency and operation flexibility. Both novel regeneration technologies have now been patented in China and are being incorporated in the design of the FCCU of the SINOPEC Changling Refinery.