example at a temperature from about 100 to 800 fahrenheit degrees above the actual operating temperature of the coking zone is admitted to reactor 1 by line 42 in an amount sufficient to maintain the coking temperature in the range of about 850 u00b0 f to about 1 400 u00b0 f preferably at a temperature ranging from about 900 to about 1 200 u00b0 f the pressure in the coking zone is maintained in the range of about 0 to about 150 pounds per square inch psig preferably in the range of about 5 to about 100 psig the lower portion of the coker serves as a stripping zone to remove occluded hydrocarbons from the coke a stream of coke is withdrawn from this stripping zone by line 18 and circulated to heater 2 conversion products are passed through cyclone 20 to remove entrained solids which are returned to the coking zone through dipleg 22 the vapors leave the cyclone through line 24 and pass into a scrubber 25 mounted on the coker if desired a stream of heavy materials condensed in the scrubber may be recycled to the coker via line 26 the coker conversion products are removed from scrubber 25 via line 28 for fractionation in a conventional manner in heater 2 stripped coke from reactor 1 cold coke is introduced by line 18 to a fluid bed of hot coke having an upper level indicated at 30 the bed is partially heated by passing a hot gas into the heater by line 32 supplementary heat is supplied to.