Patent GB-814610-A (GB)
Title: Cracking heavy hydrocarbon oils to produce olefins, motor fuels and coke
IPC: C10G9/28
Filed: 1955-11-30
Abstract: <PICT:0814610/III/1> <PICT:0814610/III/2> Heavy hydrocarbon oils are cracked to produce motor fuels, C2-C4 olefines and coke by adding the oil in a finely-divided form to a suspension of inert solid particles at a temperature above 1300 DEG  F. in a non-hydrocarbon inert gas (e.g. superheated steam, nitrogen or flue gas) and passing the mixture through an elongated reaction zone wherein the total pressure is maintained from 12 to 50 p.s.i.a., and the hydrocarbon partial pressure is maintained below 85 per cent of the total pressure; the mixture is discharged into a vapour/solids separation zone after a contact-time of less than 2 seconds, and the vapours are rapidly cooled by at least 200 DEG  F., preferably down to 600-700 DEG  F., the separation and quenching being accomplished within an average time of less than 2 seconds.  Coke particles at a temperature of about 1500 DEG  F. are supplied from standpipe 11 via U-bend 13 into leg 15.  The particles are carried at a velocity of about 16 feet per second, by steam introduced through nozzles 19, 21, 23 and 25, into reactor 17, which is 20-50 feet long and is maintained at a temperature of about 1350 DEG  F.  Reduced crude oil is sprayed through annular multiple-nozzle device 29 into the stream of hot particles as it enters the reactor.  The proportion of steam in the mixture comprises 130 weight per cent of the oil feed.  The feed produces sufficient gas upon vaporization and cracking to raise the velocity to 60 feet per second at the reactor outlet.  The total pressure in the reactor is 12 p.s.i.a. and the hydrocarbon partial pressure is 5 p.s.i.a.  The nominal gas time in the reactor is about 0.25 seconds.  The suspension of solid particles in vapours and gases is discharged into a cyclone which has a downwardly converging outer wall 31 (Fig. 2) which causes the suspension to rotate and converge as it moves downwards and, due to centrifugal force, causes the solid particles to flow down the inner wall of the cyclone.  The vapours pass through perforations 37 in the frusto-cone 33, and enter line 35.  These vapours are cooled to about 700 DEG  F. in about 0.25 seconds by contact with a hydrocarbon oil of boiling range 430-650 DEG  F. which is introduced into the apparatus through line 39.  Part of the quench liquid is sprayed, through nozzle ring 41, upwards into line 35; but part is also sprayed through nozzles 45 inside cone 33. The quenched vapours pass through line 51 into scrubbing-tower 53 which contains baffles 55.  Heavy oil is withdrawn from the base of the tower, and may be returned to reactor 17, if desired.  The scrubbed vapours pass upwards through fractionating plates 59, liquid being removed from plate 61 via line 63 and returned to a higher plate via line 65.  A C5-430 DEG  F. stream, comprising about 17 per cent of the oil feed, is removed as a side-stream from the upper portion 67 of the fractionator; and the desired quench liquid is taken off as another side-stream.  Gases are withdrawn from the top of the fractionator; these contain ethylene (10 per cent by weight of the feed), propylene (8.5 per cent), and butadiene (2 per cent).  The coke particles separated in cyclone 31 are collected in zone 81, where they are maintained as a fluidized bed by stripping gas introduced through line 83.  The stripped solids are conveyed up line 93, by high-velocity steam introduced through jets 95, 97 and 99, with simultaneous reduction in particle size.  The solids then enter burner 105; and air is supplied through inlet 107.  Fuel oil or gas is also supplied through line 107, if it is not desired to burn any of the coke.  The burner is so proportioned and the velocity of flow are such that the particles pass completely through the burner in less than 1.5 seconds.  The re-heated particles are separated from the combustion gases in cyclone 109. The solids are stripped in collecting vessel 113 by gas introduced through inlets 115, 117.  A portion of the particles is withdrawn as product coke through outlet 1171; and the remainder is recycled to the reactor.ALSO:<PICT:0814610/IV (b)/1> <PICT:0814610/IV (b)/2> Heavy hydrocarbon oils are cracked to produce motor fuels, C2-C4 olefines and coke by adding the oil in a finely-divided form to a suspension of inert solid particles at a temperature above 1300 DEG  F. in a non-hydrocarbon inert gas (e.g. superheated steam, nitrogen or flue gas) and passing the mixture through an elongated reaction zone wherein the total pressure is maintained from 12 to 50 p.s.i.a., and the hydrocarbon partial pressure is maintained below 85 per cent of the total pressure; the mixture is discharged into a vapour/solids separation zone after a contact time of less than 2 seconds, and the vapours are rapidly cooled by at least 200 DEG  F., preferably down to 600-700 DEG  F., the separation and quenching being accomplished within an average time of less than 2 seconds.  Coke particles at a temperature of about 1500 DEG  F. are supplied from standpipe 11 via U-bend 13 into leg 15.  The particles are carried at a velocity of about 16 feet per second, by steam introduced through nozzles 19, 21, 23 and 25, into reactor 17, which is 20-50 feet long and is maintained at a temperature of about 1350 DEG  F.  Reduced crude oil is sprayed through annular multiplenozzle device 29 into the stream of hot particles as it enters the reactor.  The proportion of steam in the mixture comprises 130 weight per cent of the oil feel.  The feed produces sufficient gas upon vaporization and cracking to raise the velocity to 60 feet per second at the reactor outlet.  The total pressure in the reactor is 12 p.s.i.a.; and the hydrocarbon partial pressure is 5 p.s.i.a.  The nominal gas time in the reactor is about 0.25 second.  The suspension of solid particles in vapours and gases is discharged into a cyclone which has a downwardly converging outer wall 31 (Fig. 2) which causes the suspension to rotate and converge as it moves downwards and, due to centrifugal force, causes the solid particles to flow down the inner wall of the cyclone.  The vapours pass through perforations 37 in the frusto-cone 33, and enter line 35.  These vapours are cooled to about 700 DEG  F. in about 0.25 second by contact with a hydrocarbon oil of boiling range 430-650 DEG F. which is introduced into the apparatus through line 39.  Part of the quench liquid is sprayed, through nozzle-ring 41, upwards into line 35; but part is also sprayed through nozzles 45 inside cone 33. The quenched vapours pass through line 51 into scrubbing-tower 53 which contains baffles 55.  Heavy oil is withdrawn from the base of the tower, and may be returned to reactor 17, if desired.  The scrubbed vapours pass upwards through fractionating plates 59, liquid being removed from plate 61 via line 63 and returned to a higher plate via line 65.  A C5-430 DEG  F. stream, comprising about 17 per cent of the oil feed, is removed as a side-stream from the upper portion 67 of the fractionator; and the desired quench-liquid is taken off as another side-stream.  Gases are withdrawn from the top of the fractionator; these contain ethylene (10 per cent by weight of the feed), propylene (8.5 per cent), and butadiene (2 per cent).  The coke particles separated in cyclone 31 are collected in zone 81, where they are maintained as a fluidized bed by stripping gas introduced through line 83.  The stripped solids are conveyed up line 93 by high-velocity steam introduced through jets 95, 97 and 99, with simultaneous reduction in particle size.  The solids then enter burner 105; and air is supplied through inlet 107. Fuel oil or gas is also supplied through line 107, if it is not desired to burn any of the coke.  The burner is so proportioned and the velocity of flow are such that the particles pass completely through the burner in less than 1.5 seconds.  The reheated particles are separated from the combustion gases in cyclone 109.  The solids are stripped in collecting vessel 113 by gas introduced through inlets 115, 117.  A portion of the particles is withdrawn as product coke through outlet 1171; and the remainder is recycled to the reactor.