Apparatus and process for preparation of seed coke for fluid bed coking of hydrocarbons

Claim 1

AN IMPROVED METHOD FOR PYROLIZING HEAVY HYDROCARBON FEED IN A FLUID BED AT HIGH FEED RATES WHILE PRESERVING SMOOTH FLUIDIZATION, WHICH COMPRISES, MAINTAINING A MASS OF INTERT PARTICLES AT A REACTION TEMPERATURE, INTRODUCING FLUIDIZATION GAS THROUGH SAID MASS SO AS TO FORM A FLUID BED, CONTACTING HYDROCARBON FEED WITH SAID INERT SOLIDS THEREBY CONVERTING SAID FEED TO LIGHTER HYDROCARBON PRODUCTS WHICH ARE REMOVED OVERHEAD, AND CORBONACEOUS RESIDUE WHICH CONATANTLY DEPOSITS ON SAID SOLIDS, WITHDRAWING A PORTION OF SAID CARBONACEOUS COATED SOLIDS, ATTRITING AT LEAST 3 WEIGHT % OF SAID WITHDRAWN SOLIDS, ELUTRIATING SAID ATTRITED SOLIDS AND RETURNING THUS TREATED SOLIDS TO SAID REACTION MASS SO AS TO MAINTAIN A CONSTANT MASS, NUMBER AND SIZE DISTRIBUTION OF SOLIDS THEREIN, SAID SIZE DISTRUBUTION BEING CHARACTERIZED BY LESS THAN 20 WEIGHT PERCENT OF SAID SOLIDS HAVING A DIAMETER GREATER THAN 300 MICRONS AND LESS THAN 5 WEIGHT PERCENT HAVING A DIAMETER BELOW 7K MICRONS.