US2791547A

US2791547A - Conversion of hydrocarbons with finely divided particles in a fluidized bed

Info

Publication number: US2791547A
Application number: US226894A
Authority: US
Inventors: Beiswenger Gustav Adam
Original assignee: Exxon Research and Engineering Co
Current assignee: ExxonMobil Technology and Engineering Co
Priority date: 1951-05-17
Filing date: 1951-05-17
Publication date: 1957-05-07
Anticipated expiration: 1974-05-07

Description

May 7, 1957 G. Al BEISWENGER 2,791,547

CONVERSION oF HYDRocARBoNs WITH FINELAL` DIVIDED PARTICLES IN A FLUIDIZED BED Filed May'l'?, 1951 Guscw Aciufenger 30N eater United States Patent O CONVERSION F HYDROCARBONS WITH FINELY DIVIDED PARTICLES IN A FLUIDIZED BED Gustav Adam Beiswenger, Elizabeth, N. J., assigner to Esso Research and Engineering Company, a corporation of Delaware Application May 17, 1951, Serial No. 226,894

7 Claims. (Cl. 196-55) This invention relates to treating hydrocarbons and more particularly relates to the cracking or coking of reduced crude petroleum oils or similar heavy residual oils to produce lower boiling hydrocarbons including gas oil motor fuel such as gasoline, unsaturated hydrocarbon gases and coke.

Heavy residual oils such as reduced crude oil and residues from atmospheric or vacuum distillation processes have been thermally cracked or coked in visbreaking or coking operations to form coke and lower boiling hydrocarbons which may be further treated as desired. Usually in a visbreaking operation, only a small amount of gasoline, some coke and a large amount of gas oil is obtained. Such gas oil can be further cracked thermally or catalytically to produce gasoline. In coking operations there is more gasoline formed and also more coke and less gas oil.

The present invention applies to the cracking of heavy residual oils generally, but is more specifically concerned with the coking of the heavy residual oils. The present invention is useful in processes using finely subdivided solids, bead form solids or in processes wherein a moving bed of solids is used. In the preferred form of the invention heavy residual oils are cracked in the presence of finely divided solids maintained as a dense iluidized bed.

According to the preferred form of the present inven tion the thermal decomposition or cracking of the heavy residual oil stocks is carried out in the presence of subdivided solids such as coke, pumice, kieselguhr, clay, sand, alumina, Carborundum etc. which are substantially inert, that is, they have no catalytic activity, but spent clay catalysts such as Superltrol or used synthetically prepared silica alumina catalyst having some catalytic activity may be used. The heavy residual oil to be cracked according to the present invention includes heavy residuum, pitches, tars and heavy residual oils having high boiling constituents which are not vaporizable under ordinary pressures without decomposition. The inert particles in the reaction zone act as carriers for the coke formed during the decomposition or cracking which takes place in the reaction zone and so prevent deposition of the coke on the walls of the cracking equipment. The inert solids may also act to scour the walls of the cracking equipment to remove any coke which may have deposited thereon.

The particles with the coke deposits thereon are removed and passed to a heater or burner where the coke is burned from the inert particles or some of the coke formed in the process is burned and the heated soild particles are then recycled to the reaction zone. In this way at least part of the coke deposits or coke formed during the coking is used to supply the heat of reaction or cracking. When using coke as an inert carrier, some of the coke is burned in the heater and any excess coke may be withdrawn from the reaction zone and sold or utilized as such.

ln the preferred form of the present invention the subdivided inert sold particles are maintained in a iluidized bed in the reaction or coking zone and inthe heater. The

solid particles in the reaction zone and heater are maintained in a relatively dense highly turbulent bed or layer by ilowing gasiform material upwardly through the reaction zone and heater. Above each dense fluidized bed is a dilute phase containing only a small amount of entrained catalyst which is carried out by the gasiform material leaving the reaction zone or the heater. The heavy residual oil is injected or introduced into the dense turbulent bed of subdivided particles in the reaction zone maintained at a cracking or coking temperature and substantially at atmospheric pressure.

Volatile products of coking or cracking pass overhead from the reaction zone and are treated to separate desired products. The coked particles are withdrawn directly from the dense fluidized bed in the reaction zone and at least a part thereof is passed to the heater or burner where at least part of the coke is burned from the inert particles or the coke is partially burned with air so that the particles are heated to a temperature above that maintained in the reaction zone. The iluidizing gas for the particles in the heater or burner is the air which is used to burn coke from the particles. Heated particles then are withdrawn from the dense fluidized bed in the heater or burner and returned to the reaction zone for supplying heat thereto.

One difficulty in the cracking of heavy residual oils using the subdivided solid particles in a iluidized bed or moving bed is that the linely divided particles agglomerate into clusters or form oversize particles by local overwetting of the solid heat carrier particles and such agglomeration interferes with the proper uidization of the particles in the reaction zone and interferes with the proper functioning of the reaction zone. Such agglomeration causes channelling or slugging of the uidized bed of solids.

The residual oil has extremely high boiling constituents which are not completely vaporized at the temperature of cracking or coking so that there is liquid present when the residual oil feed is introduced into the iluidized or moving bed of solids. These oversize particles or agglomerates are wetted by the oil and are eventually cemented together when the liquid oil forms coke and under these conditions uidization becomes irregular with the fluidizing gas channelling through the bed and/or slugging of the fluidized bed may also occur. Continuing the operation under these conditions will result in finally losing the uid characteristics of the bed and the process will have to be stopped.

According to this invention agglomeration of the solid particles in high temperature coking or `cracking of heavy carbonaceous residues in the presence of nely divided solids is substantially prevented or eliminated so that -the fluid characteristic of the bed of iinely divided solid particles may be maintained while the process is being carried out. Agglomeration of the finely divided solids in the iluidized bed is avoided by adding a comparatively low boiling miscible liquid such as a low boiling hydrocarbon or hydrocarbon mixture to the crude heavy residuum or pitch or heavy residual petroleum oil being cracked or coked to facilitate atomization of the residuum by flashing and vaporization of the added low boiling miscible material. In addition to the relatively low boiling hydrocarbons, a non-miscible low boiling liquid such as water may be emulsiiied with the heavy residual oil Aand the resulting mixture used in the present process.

The relatively low boiling material is preferably maintained in liquid form during preheating of the mixture of heavy residual oil and relatively low boiling material. During the preheating the residual oil and lower boi1- ing material are preferably maintained under superatmospheric pressure. After the preheating step, Ythe solution .Patented May 7, 1957y ornii'xture containing the residual oil and lower boiling Ill'ti'l iS lI-sd l'lgl Ollie" 0l' in'l IZ'ZIE'S tutti the fluidized bed of hot inert solids as extremely hnely divided liquid particles. l

Preferably the solution or mixture containing the residual oil andy lower boiling' material is' released through one or more nozzles within the dense iluidized bed of solid particles and sudden or instantaneous vaporization or 4asihing of the added Iewerbningjmaterial disrupts the residual oil particles or substantially explodes them and so causes atomizdtion of the heavy residual oil and hence; insures intirn'ate and thorough mixing of extremely finely divided residual oil particles with the finely divided solids. The sudden ia'slning'l of the residual oil also causes rapid and uniform mining of the minute particles of Vresidual oil and solid particles.

In the drawing the ligure represents one form of apparatus adapted to be used in carrying out the process of the present invention. L

Referring now to the drawing, the referenceV character Y .designates a line through whichliqiuid heavy crude residuu'rh is pumped by pump 12. The heavy crude residu'urn maybe bottoms from' atmospheric or vacuum crude distillations or may be heavy tars or pitches which contain extremely high boiling constituents which do not vaporie at ordinary pressures without decomposition. In most cases the initial boiling point of the heavy residual oil will b'e about ll00 F. or higher N200-12.50 F.) while in a few cases the initial boiling point may go as low a's 900 F., but the higher boiling heavy residual oils are preferred for this process. In present day operations the tendency is toward higher boiling heavy residual oils. A relatively low boiling liquid material is passed through line 14 by pump 16 and added to the residual oil passing through line 10. This lower `boiling material is preferably a hydrocarbon which is liquid at ordinary temperatures and pressures and is miscible with the heavy residual oil so that a solution is obtained. In addition to the liquid hydrocarbon watermay be emulsified with the oil as will be hereinafter described in greater detail.

The relatively low boiling liquid materialrto be used is one which may be maintained as a liquid before the mixture of residual oil and relatively low boiling liquid is sprayed into a reaction vessel 18. Located within the vessel 18 is a dense tluidi'zed highly turl'mlent bed 22 of finely divided solids such as sand or coke or other solids above mentioned. The dense iluidized bed 22 has a level at 24 and a dilute phase 26 thereabove. The `dense fluidized bed 22 is maintained jat a temperature of about 800 to l400 F., preferably about 850 to 1000o F.

The solution of the heavy residual `oil and relatively low boiling material is passed through preheater 28 Where the hydrocarbon solution is preheated to a temperature of about 400 to 850 F., preferably 600 to 750 F. and maintained under a pressure which may vary from about to 3000 p. s. i., preferably 100 to 400 p. s. i. The lower portion of the range of pressure would apply when utilizing a shear jet type nozzle and the `upper portion of the range of pressure would be approached if water is emulsitied with the heavy residual feed mixed with naphtha or the like.

The preheater 28 may be a coil furnace or any suitable heater. The prehe'ating is done under pressure and at a high temperature to preheat the ysolution to a high ternperature but avoiding any substantial eoking of the heavy residual oil feed. Under these selected conditions the relatively low boiling material such as naphtha -is maintained in the liquid phase and the preheated hydrocarbon mixture under pressure is passed through line 29 and is then released through the spray nozzle member 30 arranged in the llower portion of the dense fluidized bed 22 maintained at a higher' temperature and under a lower pressure vthan the hydrocarbon solution in line 29. In going through the spray nozzle or atomizer 30 provided 4 with a plurality of openings the pressure on the hydrocarbon mixture isv suddenly released'.

As the solution leaves the nozzle 30 the droplets of oil are torn apart by the sudden hashing or vaporizaton of the loW boiling material into vapors under the influence of the sudden reduction in pressure and the increase in temperature of the hydrocarbon solution introduced into the iiuidized bed 22 in reaction zone 18. The innitely small particles' of residual oil formed by thev flashing of the low boiling material are coked in Contact with the finely divided solids without wetting the particles so that no agglomeration of the particles takes place. Preferably the spray or atomizing nozzle is chosen so that the atomized droplets form a mist. Spray nozzles of the shear-jet or pressure type may be used.

More than one spray nozzle may be used at the same or different levels within the fluidized bed 22 in the reaction vessel 1S. `Instead of using the preheater 28v the hydrocarbon solution, may b e passed through' a coil in the heater 31, later to be described', and heated byV iii'-V direct vheat exchange or the solution maybe passed through a coil submerged in the dense -bed 22 in the r'- action zone. If desired, additional heat may be supplied to dense iluid bed 22 by introducing air therei'nto and burning part of Y.the coke' in bed 22 especially where -a coil is submerged therein to preheat the hydrocarbon mijn ture or solution. Also, if desired, h-ot residuun can be' transferred directly frl'orn the still producing this: nia-v te'rial. In this Acas'e the added light hydrocarbon would be introduced into transfer line 29' either with or `withoutpprehea'tng. Additional preheating could -be applied to the mixture in preheater 28'. y

The relatively vlow boiling material may be al hydrocarbon or hydrocarbon fraction boiling within the range' of about 0-650" F. and the fraction may 'be either'nar'- row or wide boiling depending somewhat on the type of effect desired. In general, low boiling' hydrocarbons would be utilized when the pressure in the noizle' is high and the temperature" low. Higher boiling hydro'- carbous or fraetions wouldbe utilized when the pressure' in the nozzle' is' low and the temperature high. y using the relatively low boiling material, the nozzles will last longer a'nd there will be less tendency to plug the nozzle Openings.

Thera'mount of relatively lofiv boiling hydrocarbon fo be added tothe' heavy kresidual oil may vary from about 0.2 to 15% by weight on the heavy residual' oil preferably 2 to 6%' by weight on the heavy residual oil. The amount of hydrocarbon to: be added `cler'iends o'n thc type no'z'zlc used andI the relative desirability of including the relatively lo'w boiliu'g component in the heavy residual oil cracking feed. The lower portion' ot the range' would apply in the' case where' water is 'ernul'sied wi'th the hevy residual oil to form la wate-inoil emulsion or where the shear` jet type' of nozzle utilizing stca'rn for atornizatiod would be employed. Thevv upper range of concentration would apply where economics' wouldkfavor the ad'ditfion of a higher boiling hydrocarbon than that which would' b'e most effective for the existing equipment and the av'ailable prehea't temperature. l

In addition to the lower boiling hydrocarbon water muy be added to and emulsitied with the residual o il t'o decrease th'e quantity of relatively lower boiling hydroczirbon required. The ypresence of water would, at least to some extent, eliminate the necessity for the added relatively low boiling hydrocarbon to supply the major portion of the force required to prbluce atomization of the heavy liquid residual oil feed. The reduced quantity of added lower boiling hydrocarbon' would stillhave the highly desirable effect of fr'othing the heavy residual oil` liquid so that it could be Vmore easily atomiz'ed.

The relatively low boiling hydrocarbons oi' hydrocarbon' mixtures which may' be 'used in uns invention may `15e a pentn fractin having a boiling range of about 50 to" iight na'ph'tha having' a editing range of about 5 to 250 F., a heavy naphtha having a boiling range of about 250 to 400 F., a light heating oil fraction having a boiling range of about 400 to 525 F. or a total heating oil having a boiling range of about 400 to 650 F. The relatively low boiling hydrocarbon can be obtained from crude oil, from other cracking processes or from the coking operation of this invention, that is, a desired fraction can be separated from the products passing through line 42 and this fraction utilized as the one to be added via line 14. The above fractions are given merely as examples and it will be clear to those skilled in the art that different fractions or hydrocarbon fractions having different boiling ranges may be used.

When water is to be emulsied with the mixture of heavy residual oil and relatively lower boiling material to form a water-in-oil emulsion, less of the lower boiling material may be used. For example, when using 0.2 to 2% by weight of naphthas on the residual oil feed about 2 to 20% by weight of water on the residual oil feed may be used. The emulsion may be formed in any known manner in high velocity mixers, homogenizers, etc. Any surface active agent or comrnercial emulsifying agent such as alkali or alkaline earth metal salts of the fatty acids, rosin acids, naphthenic acids, organic sulfates or sulfonates, lecithin, oletin of alcohol sulfates such as sodium lauryl sulfate, etc. The emulsifying agent may be used in an amount of about 0.1 to 5% by weight of the hydrocarbon mixture.

it is important to have a gap in the boiling range between the final boiling point of the added lower boiling component and the initial boiling point of the heavy residual oil feed since it gives a maximum frothing of the residual oil liquid at the nozzle 3l) to aid in atomization but then results in a comparatively low rate of vaporization during the actual coking in the fluid bed 22. This tends to minimize any tendency for the liquid to froth on the surface of the solid particles which would tend to produce a more porous and therefore more friable coke. Such a porous coke would tend to increase the production of extremely ne particles of coke upon impact of the coke particles with each other or with the walls of the reactor or associated equipment and such extremely tine particles would pass through the cyclone separators into the liquid product recovered in the fractiouating equipment.

rl`he size of the finely divided solid particles is preferably between about 100 and 400 standard mesh or finer and the superficial velocity of the gasiform material passing through the reaction zone or vessel 18 and the heater 31 is maintained between about 0.3 and 5 feet per second with about 1.5 feet per second being preferred.

The reaction vessel 18 is provided with a grid 32 at its lower portion and fluidizing gas which will presently be referred to is passed through line 34 and upwardly through the grid 32 to maintain the solid particles below spray nozzle 30 in a dense iluidized highly turbulent condition.

ri`he reaction products in vapor form leave the lluidized bed 22 and entrain some solids which form the dilute phase 26 above referred to and these vaporous reaction products are passed through a gas-solids separating means 36 such as a cyclone separator or the like for separating a large part of the entrained solids from the reaction products. The separated solids are returned to the uidized bed 22 by dip pipe 38 and the vaporous reaction products pass overhead through line 42 and may be further treated to recover desired products therefrom.

For example, the vaporous products may be passed to a fractionation system to separate the gases from the gasoline and other high boiling fractions, and the bottoms from the fractionating step may be recycled to the reaction vessel 18 via line 10.

During the cracking or coking in the reaction vessel 18 the particles become coated with coke or if coke is used as the inert material, additional coke is formed on the is endothermic, heatis lost from the reaction vessel andv must be replaced. A portion of the dense uidized solids is withdrawn through well 44 arranged in the lower por'-l tion of the reaction vessel 18. A stripping gas may be introduced into the lower portion of the well through line 46 for removing or stripping volatile hydrocarbons from the solid particles. The withdrawn solid particles are then passed into the upper portion of a standpipe 48 wherein the particles are maintained in uidized condition by the introduction of uidizing gas through one or more lines 50. v

A hydrostatic pressureA is built up by the column of these particles and is used to circulate the solid particles through the system. Standpipe 48 is provided with a control valve 52 at its lower end for controlling the rate of withdrawal of solid particles from the reaction vessel 18. The particles are passed from standpipe 48 to line 54 where they are picked up by an oxidizing gas such as air introduced through line 56 to form a dilute sus-v pension or mixture of solids and gas.

The dilute suspension or mixture is passed through line 54 into the lower portion of the heater or burner 31, above referred to, which is provided with a distribution grid 60 at its lower portion for distributing the solids and gases across the area of the vessel 31. The supericial velocity of the air passing upwardly through heater 31 is selected to be between about 0.3 and 5 feet per second to maintain the particles in a relatively dense highly turbulent iluidized condition. The fluidized layer or bed in heater 31 is designated as 62 and it has a level indicated at 64 with a dilute phase 66 thereabove. Combustion gases containing some entrained catalyst leave the bed 62 and pass through the dilute phase 66 into a gas solids separating device 68 which may beiany suitable de-. vice such as a cyclone separator. The separated solids are returned to the dense bed 62 by dip leg "l2 and the combustion gases pass overhead through line 74. Because the combustion gases contain a relatively large amount of heat, they may be passed to waste heat boilers or the like to recover heat therefrom.

During burning of coke in the burner 31 the temperature of the solid particles is maintained at a temperature between about 1000 and 1800 F. or normally about 50 to 200 F. higher than the temperature maintained in the reaction vessel 18.

The hot solid particles are withdrawn directly from the dense bed 62 in the heater 31 by means of well.76 which delivers the particles into the upper portion of a second standpipe 78 in which the particles are maintained in a dense fluidized condition by the introduction of a lluidizing gas through one or more lines 80. y

The standpipe 78 is provided with a control valve 8 at its lower end for controlling the rate of withdrawal of hot particles from the standpipe. The withdrawn particles are introduced into line 34 where they are picked up by a gas such as steam, hydrocarbon gas or vapor or the like introduced through line 86 to form a dilute suspension of solids in gas and the suspension is passed through line 34 into the lower portion of the reaction vessel 18 below distribution grid 32 as above described.

Fresh make-up solids may be introduced into the heater or burner 31 by means of line 88 which discharges below the level 64 of the dense bed therein. When coke is used as the inert carrier, some additional coke is formed during the coking process and this coke may be withdrawn from the reaction vessel 18 through line 92 and used or sold as such.

Agglomeration of the particles being contacted by the residual oil is more pronounced when the ratio of the solids to oil in the coking bed is reduced. Agglomeration is also more pronounced at lower temperatures. Experimental work has demonstrated that the degree of subdivision of the residual oil obtainable with conventional spraying or atomizing methods is insufcientto reduce agglomeration in a fluidized solids bed to a point perrnitting a feed rate of 1.5 lbs. of residual oil feed per hour per lb. of solids in the coking zone, particularly at temperatures up to about l000 F. With the present invention oil feed ratios above 3 lbs. of residual oil feed per hour per pound of solids in the coking zone and as high as 5 lbs. of residual oil feed per hour per pound of solids in the coking zone and at a temperature as low as about 800 F. may be used. With the present invention higher conversion of the residual oil to lower boiling hydrocarbons is obtained because there is better and more intimate and thorough contact of the sprayed or atomized residual oil and the solid particles.

`By decreasing the amount of light hydrocarbon or hydrocarbons admixed with the residual oil, the average boiling point of the light component can be decreased. Increased pressure or lower ltemperature in preheater 28 has a similar effect. Instead of adding the preheated feed into the lluidized bed 22, it may be passed through a nozzle arranged in transfer line 34 to spray or atomize the feed there.

As a specific example, 100 parts by weight of residual oil having an initial boiling point of about ll F. are mixed with about `parts by `weight of naphtha having a boiling range ot about 250 to 400 F. The solution is heated to a temperature of about 750 F. and under a pressure of about 250 p. s. i. g. This heated solution runder pressure is then sprayed into a bed of lnely divided iluidized coke particles of 100 mesh to 400 mesh maintained at a temperature of about 950 F. and essentially at atmospheric pressure. A separate stream of iluidizing gas such as steam is introduced below the injection point of nozzle 30 to maintain the particles in a uidized condition. Under these conditions a feed rate of about 3 pounds of residual oil per hour per pound of solids within the coking zone 18 may be obtained with substantially no agglomeration of solid particles in the coking zone and the process can be maintained as long as desired.

What is claimed is:

l. In a method of coking high boiling heavy residual petroleum oils in contact with a tluidized mass of subdivided solids maintained at coking temperature and substantially at atmospheric pressure, the improvement which comprises eliminating agglomeration of the solid particles caused by wetting of the solids with residual oil components not vaporizable at said coking temperature by adding a comparatively low boiling hydrocarbon material vaporizable at a temperature substantially below said coking temperature to the residual petroleum oil, preheating the resulting liquid mixture under superatmospheric pressure to below said coking temperature and then spraying the preheated pressurized mixture into the mass of subdivided solids maintained at a higher temperature and lower pressure, thereby suddenly reducing the pressure on the liquid mixture during spraying so that the low boiling material flashes or vaporizes suddently Vand causes instantaneous disruption and atomization of the residual oil in the tluidized mass `of subdivided solids during coking whereby local overwetting of said solids and consequent agglomeration thereof are substantially prevented.

2. A method laccording to claim l wherein the low boiling hydrocarbon is a naphtha having a boiling range of about 250 to 400 F. andthe amount .of -naphtha used is about 2 to 10% by weight per 100 parts by weight of the residual petroleum oil.

3. In a method of coking high boiling heavy residual petroleum oils in contact `with a iluidized mass of subdivided solids maintained at coking temperature and substantially at atmospheric pressure, the improvement which comprises eliminating agglomeration of the solid particles caused by local overwettiug of the solids with residual -oil components not vaporizable at said coking tern-perature by adding acomparatively low boiling hydrocarbon material completely vaporizable at a temperature substantially below said coking temperature to the residual oil, emulsifying water with the residual oil-hydrocarbon material mixture, preheating the resulting liquid mixture under superatmospheric pressure to a temperature suiciently high to cause substantially instant vaporization of said water and hydrocarbon material upon release from said superatmospheric pressure but below said coking temperature and then spraying the preheated pressurized liquid mixture into the mass of subdivided solids maintained at a higher temperature by lower pressure and suddenly reducing the pressure on the liquid mixture during spraying so that the low boiling material and water dash or vaporize suddenly and cause instantaneous disruption and atomization of the residual oil in the Huidized mass of subdivided solids during coking, whereby said local overwetting and agglomeration are substantially prevented.

4. In a method according to claim l wherein the residual oil is contacted with a fluidized bed of finely divided solid particles maintained at a coking temperature of about 800 to i400o F. and substantially at atmospheric pressure, the improvement which comprises spraying into the body of the iuidized bed of inely divided solids a single liquid mixture comprising residual petroleum oil and a low boiling naphtha and preheated to a temperature of about 600 to 750 F. and during preheating being maintained under a superatmospheric pressure of about p. s. i. to 400 p. s. i.

5. A method according to claim l wherein the pounds of residual oil per hour per pound of solids in the coking zone is between about 3 and 5 and the amount of low boiling hydrocarbon used is about 3 to l0 parts by weight per 100 parts by weight of the residual petroleum oil.

6. A method of coking high boiling residual petroleum oils containing constituents unvaporizable at ordinary pressures without decomposition which comprises spraying into a iluidized mass of finely divided solid particles in a coking zone maintained at a cracking temperature of about 850 to ll00 F. and substantially at atmospheric pressure a single liquid solution comprising residual petroleum oil and an added low boiling naphtha and preheated to a temperature of about 600 to 750 F. and during preheating maintained under a superatmospheric pressure of about 100 p. s. i. to 400 p. s. i. so that the low boiling naphtha remains liquid and when the liquid solution is suddenly released through the spray into the luidized bed of solids the low boiling naphtha suddenly ashes and causes an extremely line dispersion of the residual oil in contact with the solid particles of the lluidized bed, removing solid particles containing coke from said coking zone and passing them to a burning zone, passing an oxidizing gas upwardly through said burning zone to maintain the solid particles in a dense fluidized highly turbulent condition during burning of the coke to raise the temperature of the solid particles to a temperature of about 50 to 250 F. higher than that in said coking zone, withdrawing the so-heated solid particles from said burning zone and passing them to the coking Zone to supply some of the heat of reaction thereto.

7. In a method of coking high boiling residual petroleum oils containing constituents unvaporizable at ordinary pressure without decomposition wherein the residual oil is contacted with a iluidized bed of nely divided solid particles maintained at a coking temperature of about 800 to 1400 F. and substantially at atmospheric pressure, the improvement which comprises spraying into the body of the iluidized bed of nely divided solids a single liquid mixture comprising residual petroleum oil having an initial boiling point of about 1100 F. and a relatively low boiling hydrocarbon material having a iinal boiling point below about 525 F. by suddenly and drastically reducing the pressure on said liquid mixture, said residual oil-hydrocarbon material having water emulsied therewith, preheating said emulsitied mixture to about 600 to 750 F. and maintaining the mixture prior to spraying under a superatmospheric pressure of about 1000 lbs. per square inch to 3000 lbs. per square inch so that the low boiling hydrocarbon material and Water remain substantially liquid and when the emulsi ed mixture is sprayed into the hot fluidized bed of solids the low boiling hydrocarbon material and water ash and cause a fine dispersion or atomization of the residual oil in contact with the hot solid particles of the fluidized bed and intimate and thorough conact of the residual oil and soli-d particles is obtained.

References Cited in the tile of this patent UNlTED STATES PATENTS

Claims

1. IN A METHOD OF COKING HIGH BOILING HEAVY RESIDUAL PETROLEUM OILS IN CONTACT WITH A FLUIDIZED MASS OF SUBDIVIDED SOLIDS MAINTAINED AT COKING TEMPERATURE AND SUBSTANTIALLY AT ATMOSPHERIC PRESSURE, THE IMPROVEMENT WHICH COMPRISES ELIMINATING AGLOMERATION OF THE SOLID PARTICLES CAUSED BY WETTING OF THE SOLIDS WITH RESIDUAL OIL COMPONENTS NOT VAPORIZABLE AT SAID COKING TEMPERATURE BY ADDING A COMPARATIVELY LOW BOILING HYDROCARBON MATERIAL VAPORIZABLE AT A TEMPERATURE SUBSTANTIALLY BELOW SAID COKING TEMPERATURE TO THE RESIDUAL PETROLEUM OIL, PREHEATING THE RESULTING LIQUID MIXTURE UNDER SUPERATMOSPHERIC PRESSURE TO BELOW SAID COKING TEMPERATURE AND THEN SPRAYING THE PREHEATED PRESSURIZED MIXTURE INTO THE MASS OF SUBDIVIDED SOLIDS MAINTAINED AT A HIGHER TEMPERATURE AND LOWER PRESSURE, THEREBY SUDDENLY REDUCING THE PRESSURE ON THE LIQUID MIXTURE DURING SPRAYING SO THAT THE LOW BOILING MATERIAL FLASHES OR VAPORIZES SUDDENLY AND CAUSES INSTANTANEOUS DISRUPTION AND ATOMIZATION OF THE RESIDUAL OIL IN THE FLUIDIZED MASS OF SUBDIVIDED SOLIDS DURING COKING WHEREBY LOCAL OVERWETING OF SAID SOLIDS AND CONSEQUENT AGGLOMERATION THEREOF ARE SUBSTANTIALLY PREVENTED.