GB720612A - A process of converting hydrocarbon materials containing distillable and non-distillable hydrocarbon constituents into distillate oils and coke - Google Patents

Abstract

<PICT:0720612/III/1> Hydrocarbon materials containing distillable and non-distillable constituents are distilled to give distillate oils and non-distillable residue, the residue is thermally cracked in liquid phase in the presence of added subdivided solids to coke and distillable oils, the coke and cracked oil are separated and the oil returned to the distillation zone. As described, crude oil mixed with cracked oil from line 3 is preheated at 5 and distilled in column 9. Reduced crude bottoms are taken, preferably via heater 21, to vacuum flash tower 23, a gas oil being recovered overhead and a pitch boiling above 1100 DEG F. being taken via heater 37 to heat-soaker 41. Fresh seed coke of particle size 5-250 microns may be added from lock-hopper 33 but is preferably added as a slurry from line 35. The pitch is cracked at 780-820 DEG F. and about 2000 p.s.i. in coil 37 and soaker 41 where it is agitated by propeller 42. Total cracking time may be 1-3 hours. From soaker 41 cracked products are taken, after releasing pressure, to flash drum 45 from which vapours are fed back to column 9 and a slurry of heavy oil and coke taken to a separator which may be a rotary filter 50. The cracked products in line 48 may be further cooled to 200-450 DEG F. by cooled coke-free oil from line 51. Liquid filtrate and vapours are passed from filter 50 by line 52 into tank 54 from which liquid is taken to column 9 by line 3 and vapours recovered by line 61 or passed to column 9 by line 63. Wet coke from filter 50 is dried at 67, vapours passing to tank 54. Dry coke is withdrawn at 71, part being taken to line 35 to be slurried with product-naphtha from line 13 and fed to the cracking stage. Alternatively wet coke from filter 50 may be passed by line 77 to line 35. The seed coke may be disintegrated at 79. To start up the process other subdivided solids such as clay or ashes may be used. In a modification the vacuum tower 23 is omitted and the atmospheric residuum in line 19 passed direct to line 31. Products from tower 9 may be subjected to standard operations such as stabilization, absorption, alkylation, hydroforming, and catalytic cracking to obtain the required products. In an example a mixed crude is fractionated, the bottoms are blended with 14 per cent. heavy naphtha containing 53 pounds of 100-200 mesh coke per barrel, and heated to 800 DEG F. under a pressure of 2100 p.s.i. for 150 minutes. After filtering the coke product is heated to 1000 DEG F. in a retort, a yield of 31 pounds of coke per barrel of feed to the cracking stage being obtained.