Fluid catalyst process and apparatus

Claim 1

IN THE OPERATION OF AN UPFLOW FLUID CATALYST REACTOR THE IMPROVEMENT WHICH COMPRISES MAINTAINING A BED OF FLUIDIZED CATALYST IN A REACTION ZONE, CONTINUOUSLY INTODUCING REACTANT VAPORS AND CATALYST INTO THE BOTTOM OF SAID BED IN SAID REACTION ZONE AT FIXED DESIRED RATES, CONTINUOUSLY WITHDRAWING REACTANT VAPORS CONTAINING SUSPENDED CATALYST FROM THE TOP OF SAID REACTION ZONE THE QUANTITY OF CATALYST CARRIED IN SUSPENSION BEING AT LEAST EQUAL TO THE QUANTITY OF CATALYST IN SUSPENSION IN SAID VAPORS INTRODUCED, SEPARATING AT LEAST THE MAJOR AMOUNT OF CATALYST FROM THE WITHDRAWN SUSPENSION AND COLLECTING THE SEPARATED CATALYST AS A DENSE BED SEPARATE FROM BUT CONTIGUOUS TO SAID FIRST-MENTIONED FLUIDIZED CATALYST BED, AND MAINTAINING THE LEVEL OF FLUIDIZED CATALYST IN SAID FIRSTMENTIONED FLUIDIZED CATALYST BED AT A DESIRED LEVEL ABOVE THE EQUILIBRIUM LEVEL CORRESPONDING TO SAID FIXED DESIRED RATES BY TRANSFERRING CATALYST FROM SAID SECOND-MENTIONED DENSE FLUIDIZED BED TO SAID CONTIGUOUS FIRST-MENTIONED FLUIDIZED BED WITH STEAM, THE RATE OF SAID CATALYST TRANSFER AND HENCE THE BED LEVEL BEING CONTROLLED BY CONTROL OF THE STEAM RATE.