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 suppli ed at several different levels in the riser. Simulations based on the riser regeneration model previously developed by us show that this met hod 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 degrees C. The second design is a two-stag e riser FCC regenerator, which connects two riser regenerators in seri es. This novel design combines the advantages of both the riser regene ration and the conventional two-stage turbulent bed regeneration. It a lso provides significant advantages over the single riser regenerator: operating the second riser at high temperature without catalyst hydro thermal 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.