Method of sealing moving bed conversion reactor

Claim 1

IN A MOVING BED HYDROCARBON CONVERSION PROCESS WHEREIN A GRANULAR CATALYST IS PASSED AS A COMPACT BED THROUGH A REACTION ZONE UNDER ADVANCED PRESSURE, A REGENERATION ZONE UNDER SUBSTANTIALLY LOWER PRESSURE AND RETURNED TO THE TOP OF THE REACTION ZONE, THE IMPROVED METHOD OF FEEDING THE CATALYST INTO THE TOP THE REACTION ZONE AGAINST THE ADVANCE PRESSURE THEREIN, COMPRISING: SUPPLYING CATALYST CONTINUOUSLY FROM THE BOTTOM OF THE REGENERATION ZONE TO A SURGE ZONE LOCATED SUBSTANTIALLY ABOVE THE REACTION ZONE TO FORM A COMPACT MASS OF CATALYST IN SAID ZONE, GRAVITATING CATALYST DOWNWARDLY FROM THE BOTTOM OF SAID SURGE ZONE THROUGH A SUBSTANTIALLY ELONGATED PASSAGE OF RESTRICTED CROSS-SECTION AS A COMPACT COLUMN, PASSING CATALYST AS A COMPACT MASS THROUGH A SEAL ZONE LOCATED ABOUT THE BOTTOM OF SAID ELONGATED COLUMN, PASSING CATALYST DOWNWARDLY AS A COMPACT COLUMN OF RESTRICTED CROSS-SECTION FROM THE BOTTOM OF SAID SEAL ZONE INTO TTHE TOP OF SAID ADVANCED PRESSURE REACTION ZONE TO CONTINUOUSLY REPLACED CATALYST HEING WITHDRAWN FROM THE BOTTOM OF SAID ZONE, CONTINUOUSLY MEASURING THE PRESSURE DIFFERENTIAL BETWEEN A POINT INTERMEDIATE SAID ZONE AND SAID REACTION ZONE AND INTRODUCING SUFFICIENT STEAM INTO SAID SEAL ZONE TO MATINTAIN THE PRESSURE DIFFERNTIAL AT A PREDETERMINED VALUE, SUFFICIENT TO PREVENT REACTANT VAPORS FROM FLOWING UPWARDLY FROM THE REACTION ZONE THROUGHT GRAVITATING COLUMN OF CATALYST TO SAID SEAL ZONE, MEASURING THE PRESSURE DIFFERNTIAL BETEWEEN TWO VERTICALLY SPACED POINTS NEAR THE LOWER END OF SAID SEAL LEG, VENTING STEAM FROM SAID SEAL ZONE IN RESPONSE TO SAID MEASUREMENT TO PREVENT SAID PRESSURE DIFFERENTIAL FROM RISING ANOVE A PREDERTERMINED MAXIMUM, BELOW THAT PRESSUR DIFFERENTIAL WHICH WOULD CAUSE INTER-