Pebble heater

Claim 1

IN A PROCESS FOR CONVERSION OF HYDROCARBON INVOLVING CRACKING WHEREIN HYDROCARBON VAPOR IS PASSED UPWARDLY THROUGH A CONFINED UPRIGHT VERTICALLY EXTENDING ZONE IN INTIMATE CONTACT WITH A GRAVITATING BED OF HOT, REFRACTORY, PEBBLES INTRODUCED INTO THE UPPER PORTION OF SAID ZONE AND FLOWING OUT THE BOTTOM THEREOF, THEREBY HEATING AND AT LEAST PARTIALLY CRACKING SAID HYDROCARBON, AND AN EFFLUENT HYDROCARBON STREAM SUBJECT TO DEGRADATION REACTIONS WITH CONCOMITANT CARBON DEPOSITION IS REMOVED FROM THE UPPER PORTION OF SAID ZONE, THE IMPROVEMENT WHICH COMPRISES CONTINUOUSLY INTRODUCING SAID PEBBLES TO SAID ZONE THROUGH AN INLET AT THE JUNCTURE OF ITS UPPER AND LATERAL BOUNDARIES, THEREBY FORMING AND MAINTAINING A TOP SURFACE ON SAID PEBBLE BED CONFORMING TO THE NATURAL SLOPE THEREOF AND OBLIQUE TO THE AXIS OF SAID ZONE, AND CONTINUOUSLY FUNNELING THE CRACKED EFFLUENT THROUGH A ZONE OF GRADUALLY AND UNIFORMLY DECREASING VOLUME IN THE DIRECTION OF FLOW TO A VAPOR OUTLET OPPOSITE THE CENTER OF THE TOP SURFACE OF SAID PEBBLE BES SO AS TO DECREASE THE AVERAGE RESIDENCE TIME OF SAID EFFLUENT IN THE UPPER PORTION OF SAID ZONE AND REDUCE THE FORMATION OF CARBON THEREIN.