Heat recovery in a fluidized catalyst regeneration

Claim 1

IN THE REGENERATION OF FINELY DIVIDED CATALYST WHEREIN A STREAM OF OXIDIZING GAS IS PASSED UPWARDLY THROUGH A REGENERATING ZONE CONTAINING A BODY OF FINELY DIVIDED CATALYST OF VARYING PARTICLE SIZE AT A VELOCITY ADJUSTED TO MAINTAIN A RELATIVELY DENSE LAYER OF CATALYST IN THE BOTTOM PORTION OF SAID REGENERATOR AND A STREAM OF HOT, SPENT REGENERATION GAS CONTAINING A SMALL AMOUNT OF ENTRAINED CATALYST POWDER IS REMOVED FROM THE UPPER PORTION OF SAID REGENERATOR AND PASSED THROUGH A HEAT EXCHANGER TO RECOVER HEAT THEREFROM; THE IMPROVEMENT WHICH COMPRISES WITHDRAWING A SMALL STREAM OF RELATIVELY COARSER CATALYST FROM THE BOTTOM PORTION OF SAID REGENERATOR AND INJECTING SAID STREAM OF COARSER CATALYST INTO THE GAS STREAM CONTAINING SAID ENTRAINED CATALYST PRIOR TO PASSING TO SAID HEAT EXCHANGER IN AN AMOUNT SUFFICIENT TO PREVENT ACCUMULATION OF THE FINE ENTRAINED POWDER ON THE SURFACE OF SAID HEAT EXCHANGER.