Method and apparatus for separating granular particles from lift gas in a pneumatic lift

Claim 1

IN A MOVING BED CONVERSION PROCESS IN WHICH A GRANULAR CATALYST IS GRAVITATED AS A COMPACT MASS THROUGH REACTION AND REGENERATION ZONES AND IS ELEVATED THROUGH AN UPWARDLY EXTENDING LIFT PASSAGE BY THE FLOW OF A STREAM OF LIFT GAS, THE IMPROVEMENT IN THE METHOD OF SEPARATING THE LIFT GAS AND SOLID PARTICLES AFTER DISCHARGE FROM THE LIFT PASSAGE WHICH COMPRISES: DISCHARGING THE MIXED STREAM OF GAS AND SOLIDS FROM THE TOP OF THE LIFT PASSAGE INTO A SEPARATION ZONE OF ENLARGED CROSS-SECTION WHEREBY THE SOLIDS LOSE THEIR UPWARD VELOCITY AND COMMENCE TO FALL TO THE LOWER PORTION OF THE SEPARATION ZONE, MAINTANING A BED OF THE SOLID PARTICLES ON THE FLOOR OF THE SEPARATION ZONE AND ABOUT THE UPPER END OF THE LIFT PASSAGE, INTRODUCING A GAS INTO THE REGION BETWEEN THE LIFT PASSAGE AND THE WALL OF THE SEPARATION ZONE AT A LEVEL ABOVE THE BED OF SOLID PARTICLES, TO TRAVEL UPWARDLY TOWARD THE UPPER PORTION OF THE SEPARATION ZONE IN COUNTERCURRENT FLOW WITH THE FALLING SOLIDS, AT AN UPWARD VELOCITY SUFFICIENT TO SUBSTANTIALLY IMPEDE THE FALLING CATALYST PARTICLES, WHEREBY THE PARTICLES STRIKE THE SURFACE OF THE BED OF SOLIDS IN THE LOWER PORTION OF SAID SEPARATION ZONE AT A VELOCITY SUBSTANTIALLY LOWER THAN IF THEY WERE PERMITTED TO FALL FREELY, WHEREBY THE BREAKAGE OF THE PARTICLES IS MINIMIZED, COMMINGLING THE RISING STREAMS OF GAS AND WITHDRAWING THE GAS FROM THE UPPER PORTION OF THE SEPARATION ZONE, WITHDRAWING AT LEAST ONE COMPACT STREAM OF SOLID PARTICLES FROM THE LOWER PORTION OF SAID SEPARATION ZONE, AT A RATE LOW ENOUGH TO MAINTAIN A BED SURFACE WITHIN THE LOWER PORTION OF SAID SEPARATION ZONE, WHEREBY THE SOLID PARTICLES ARE SEPARATED FROM THEIR LIFTING GAS WITH A MINIMUM OF PARTICLE ATTRITION AND BREAKAGE.