US3144400A

US3144400A - Fluid coking process

Info

Publication number: US3144400A
Application number: US76194A
Authority: US
Inventors: Harold N Weinberg; Albert S Perley; Jr Frederick J Kaiser
Original assignee: Exxon Research and Engineering Co
Current assignee: ExxonMobil Technology and Engineering Co
Priority date: 1960-12-16
Filing date: 1960-12-16
Publication date: 1964-08-11
Anticipated expiration: 1981-08-11

Description

Harold N. Weinberg Albert 8. Perley Frederick J. KaiserJ Jr.

By/y/My Inventors Potent Atfrney United States Patent O arreso@ FLUID CUKNG PRCESS Harald N. Weinberg, East Brunswick, Albert S. Perley,

Martinsville, and Frederick J. Kaiser, Jr., Morris Plains, NJ., assignors te Esso Research and Engineering Company, a corporation of Delaware Filed Dec. 16, 1960, Ser. No. 76,194 9 Claims. (Cl. 208-81) This invention relates to fluid coking of high boiling hydrocarbons and more particularly relates to fluid coking in which a whole petroleum crude oil is fed to the scrubber or scrubber-fractionating section of a fractionating tower to reduce the whole petroleum crude oil to a high cut point fraction and a residual fraction.

The uid coking process is a well known process and is disclosed in Pfeiffer et a1. Patent 2,881,130, granted April 7, 1959. The fluid coking process is used to crack petroleum residues to make gas oil that is useful as a feedstockV for catalytic cracking. In these cases the residual oil is recovered as bottoms in a pipe still operation which may be an atmospheric pipe still and/ or a vacuum pipe still.

In the Huid coking process a heavy residuum oil is injected into a reactor or coking vessel containing a dense uidized turbulent bed of hot finely divided solids such as coke particles. The heat of cracking or coking the heavy oil is supplied by withdrawing solids from the coking vessel, heating them and returning the heated solids to the coking Vessel.

Inthe present invention the fluid coking process is modified so that the whole petroleum crude oil is fed or introduced into the scrubber section of the fractionator with products from the coking vessel for reduction to one or morev high cut point fractions in one operation. With the present invention the vacuum and atmospheric pipe stills for fractionating a whole crude into lower boiling fractions and a residual fraction are eliminated. Bottoms from the scrubber section form the heavy oil feed going to the coking vessel. The whole crude is fractionated into several fractions including lower boiling hydrocarbons and is reduced to a high cut point fraction, i.e., 800- 1l00 F. FVT (final vapor temperature) and a residual or bottoms fraction. The process is especially useful on heavy crudes and/or in small refineries and/ or in an area where a market exists primarilyfor gasoline, some middle distillates and little or no fuel oil.

Heat is supplied in the conventional fluid coking process by withdrawing coke particles from the coking vessel and burning a part thereof in a burning or heating vessel to raise the temperature of the coke particles about 150 F. to 200 F. higher than the temperature in the coking vessel and then returning the so-heated coke particles to the coking vessel. With the present invention an additional amount of heat is supplied to the coke particles being returned to the coking vessel from the burner vessel to supply heat for vaporizing and fractionating the whole crudepetroleum oil.

To supply this additional heat in the distillation step a vaporizable liquid is injected into the coking vessel to absorb additional heat brought in from the burner vessel and thus be vaporized. The heated vapors are then passed into the scrubber section to supply this additional heat.

In the drawing the Figure represents one form of apparatus adapted to carry out the invention, but other forms of apparatus may be used.

Referring now to the drawing, the reference character 10 designates a line for introducing the petroleum oil feed into an intermediate portion of a scrubbing section 12. The petroleum oil feed is a whole crude petroleum oil and may have an API gravity of between about 10 and 40 and a Conradson carbon content of between 3,144,400 Patented Aug. 11, 1964 ICC about 0.3 and 15 weight percent. The whole crude petroleum oil contains light hydrocarbon gases and light hydrocarbons and has a nal boiling point above about 1l00 F. The feed is preferably preheated by conventional means to a temperature between about 600 F. and 800 F. In the scrubbing section 12 the oil feed flows down and countercurrently contacts upflowing hot vapors from the coking step leaving through the outlet pipe or chimney 16 leading from the cyclone separation means 18.

The cyclone separator 18 is arranged in the upper portion of the coking vessel or reactor 22 and is shown as a single cyclone separator but preferably includes a series of cyclone separators. The cyclone separator 18 is provided with an inlet 24 and a dipleg 26 for returning separated solids to the dense turbulent fluidized bed of solids 28 contained in the coker vessel 22. The fluid bed of solids has a level indicated at 29.

Vessel 22 is cylindrical and vertically arranged and has a rounded top wall 30 through which chimney 16 extends and terminates above the top vwall 30. Scrubber section 12 is also a vertically arranged cylindrical vessel which is shown as smaller in horizontal cross section than vessel 22 with the scrubber section 12 superimposed on the top of Vessel 22. However, scrubber section 12 may be the same as or smaller in horizontal cross section than Vessel 22. The fractionatingsection may be superimposed on scrubber section 12 with the vessel 22 and scrubber section 12 and the fractionating section being in vertical alinement. The fractionator 31 is preferably a separate vessel located at grade and receives the total overhead `Coker vapors from scrubber section 12.

Cracked vapors and steam and other vapors leaving the dense turbulent fluidized bed of solids 28 in vessel 22 contain entrained solids and these are removed in the cyclone separator means 18. The separated hot vapors and gases pass upwardly through cyclone separator outlet pipe 16 into scrubber section 12 and as above pointed out are contacted by the whole crude oil feed. The scrubber section 12 is preferably provided with disc and doughnut means 32 to improve contacting between the liquid oil feed and the cracked gases and vapors to scrub out any.

entrained finely divided solids from the vapors and also to condense the heavy ends from the cracked vapors. At the same time relatively low boiling hydrocarbons are Vaporized from the whole crude oil and taken overhead.

The heavy ends or condensate fraction collects on the bottom of scrubber section 12 and is withdrawn therefroml through line 34 and passed by pump 36 through cooler 38 and a portion thereof returned to the upper portion of the scrubber section 12vthrough line 39 as pumparound liquid to assist in the removal of heat from the scrubber section. In one form of the invention the bottoms from scrubber section 12 are coked to extinction. A portion of the heavy condensate fraction from line 34 may be withdrawn from the process through line 40 for use as fuel oil or to adjust the coker operation. Another portion of the heavy condensate may be passed through line 42, for admiXture with the whole crude oil feed in line 10. The larger or major portion of the heavy condensate is passed through line 44 as feed to the coker reactor 22 presently to be described.

A portion of the whole crude oil feed and heavy condensate oil mixture passing through line 10 may be passed through line 46 for admixture with heavy condensate oil from line 44 as feed to the coker reactor 22.

Vapors leave the top of the scrubber section and flow through line 50 and are introduced into the bottom portion of the fractionator 31 which is provided with any desirable contacting means such as perforated plates or bubble caps 52 and here additional fractionation of the hydrocarbons is effected. The overhead vapors contain 3 virgin and cracked products. Between about 50 and 70% by volume of whole crude is vaporized.

The products of coking are coke, C3 and lighter hydrocarbons, gasoline and gas oil. The higher boiling hydro carbons are condensed and collect in the bottom of the fractionator 31 and are passed through line 54 by pump 56 into the upper portion of scrubber section 12 as reflux liquid. This condensate liquid in line 54 comprises a heavy gas oil fraction, part of which is withdrawn through line 58 and utilized as catalytic cracking feed or blended into fuel oil and the rest returned to scrubber section 12 through line 54. The withdrawn heavy gas oil fraction comprises virgin and cracked components and is at a temperature between about 450 F. and 650 F. and before being returned to the scrubber section 12 it is passed through a heat exchanger 60 such as a waste heat boiler to produce steam which may be passed through line 62 to a steam drum 64 and maintained there under a pressure between about 50 and 650 p.s.i.g. and between about 280 F. and 500 F. The steam so produced is withdrawn through line 66 and used in part at least in the coking process as for example in the stripping zone.

A light gas oil fraction containing virgin and cracked components is withdrawn from an intermediate portion of the fractionator 31 through line 70 and passed by pump 72 through waste heat boiler or other heat exchanger '74 for return through line 76 to an upper portion of the fractionator 31 as reflux. Steam from waste heat boiler 74 is passed through line 78 into steam drum 64. A portion of the light gas oil is withdrawn from the process through line 80.

The vapors pass overhead through line 82 and condenser 84 to condense normally liquid hydrocarbons and water from gases. The light condensate is passed to separator S6 from which gases are withdrawn overhead through line 88. The water may be drawn off through line 90. The condensed hydrocarbons are withdrawn through line 92 and a portion withdrawn from the process as naphtha through line 94 and the rest returned to the upper portion of the fractionator 31 as reflux liquid through line 96 by pump 98. The naphtha and gas fractions withdrawn from fractionator 31 comprise virgin and cracked constituents.

The larger or major portion of the scrubber bottoms is passed through

valved lines

34 and 44 for introduction as oil feed to the coking vessel 22. Preferably the oil feed from line 44 is passed through

separate lines

102, 104 and 106 provided with nozzles for introducing the oil feed into the body of the dense turbulent fluidized bed of solids. While three lines are shown for introducing the oil feed into the coking vessel, it is to be understood this is by way of example only as it is preferred to supply the oil feed through more than one nozzle to effect good distribution of the heavy oil on the solids in the dense uidized bed 28 and more lines and nozzles may be used, if desired.

The temperature in the coking vessel 22 is between about 850 F. and 1200" F. and preferably between about 900 F. and 1l00 F. for coking operations where gas oil and middle distillates are desired. Where higher temperatures are desired to produce unsaturated hydrocarbons for chemical processes, the temperature in the reactor may go as high as 1600 F.

During the cracking or coking operation a portion of the oil feed is converted to coke which is deposited on the fluidized solid particles in the coking vessel 22. The rest of the oil charge is converted to gas and normally liquid distillate hydrocarbons. The solids in the coking vessel are preferably coke and have an average particle size ranging between about 75 and 500 microns in diameter with a preferred average particle size range between about 100 and 300 microns. Preferably not more than about 1.0% has a particle size above about 500 microns and about to 20% of the particles have an average size between about 40 and 125 microns. These liner particles are helpful in improving iiuidization of the iiuidized bed and the circulation of solids through the unit.

The coke solids are maintained as a dense turbulent iiuidized bed 28 by vapors and steam passing upwardly through the dense bed. The average superficial velocity of the rising gases in the coking vessel 22 is preferably maintained between about 0.5 and 5 feet per second depending on the size of the particles making up the bed.

The bottom portion of the coker vessel 22 has a reduced cylindrical section which functions as the stripping section and is preferably provided with disc and doughnuts 112 for improving contacting between the coke particles passing down through the stripping section 110 and the stripping gas such as steam which is passing upwardly through the striping section 110. The stripping gas is introduced into the bottom section of the stripping section through one or more lines 114. Additional steam may be added to iiuidized bed 28 in coking vessel 22 through line 116. Steam from steam drum 64 may be used as stripping steam supplied to line 114 and/ or line 116.

The intermediate section between the top of the stripping section 110 and the bottom of the main section of the coker vessel 22 is a frustum of a cone which expands outwardly and upwardly from the stripping section to the bottom portion of the coking vessel 22 and is designated as 118. The varying diameter of the reactor controls the superficial velocity within desirable limits required for proper iiuidization in the reactor.

During the coking operation as above pointed out, coke is deposited on the coke particles formed in the dense fluidized bed and the particles continue to grow and some means must be provided to supply fine solid or seed particles to the dense fluidized bed to maintain the fluidized condition. To maintain the desired amount of solids in the unit and of the desired particle size range, it is necessary to replace the coarser particles with iiner coke particles. This may be done by withdrawing some of the larger particles, grinding them and returning the ground particles to the coker vessel 22 or the burner vessel hereinafter to be described.

Preferably, the steam introduced through line 114 into the stripping section is utilized as an attritting gas to break up coarse particles and produce fine particles so that it is not necessary in the preferred form of operation to remove large coke particles from the unit to produce finer coke particles. One or more steam nozzles may be used for injecting the steam from line 116 into the conical section 118 at a velocity between about 2000 and 3500 feet per second to cause attrition of the larger coke particles to produce seed coke.

A liquid such as water or a liquid hydrocarbon such as coker naphtha, coker heating oil or coker gas oil which are obtained as products from the coker fractionator 31 is introduced above the stripping section 110 into the lower portion of the dense fiuidized bed 28 in the coker vessel 22 through line 120. This is one of the features of the present invention and will hereinafter be described in greater detail. The liquid may be at room temperature or higher or lower. The water or other liquid is added in addition to the steam added through lines 114 and 116. Briefly, this liquid is added as liquid to provide an additional heat carrying and partial pressure reducing medium which passes from the coking vessel 22 to the scrubber section 12 in order to supply heat and partial pressure reduction for the vaporization of the whole crude oil introduced through line 10 into the scrubber section. The additional or incremental heat is supplied to the coker vessel 22 by the burner vessel 122 which will now be described. The burner vessel 122 supplies heat of coking and heat of vaporization of introduced liquid from line 120.

Stripped coke solids are withdrawn from the bottom of the stripping section 110 through standpipe or other means 130 and mixed with air introduced through line 132 and the suspension passed through line 134 into the bottom of the burner vessel 122 whichis a vertically arranged cylindrical vessel. The burner vessel is maintained at a temperature between about 900 F. and l500 F. In the burner vessel 122 a part of the coke is burned to raise the temperature of the coke particles which are to be returned to the coking vessel. During the burning and heating of the coke particles, the particles are maintained as a dense fluidized turbulent bed indicated at 136 having a level at 13S. Heated coke solids are withdrawn from the bottom portion of the burner vessel 122 through standpipe or other means 140 and mixed with a gas such as steam introduced through line 142 and this mixture or suspension passed through line 144 into the upper portion of the dense fluidized turbulent bed 2S in the coker vessel 22. The steam for line 142 may be supplied from drum 64.

Combustion or flue gases pass upwardly through the burner vessel 122 at a velocity between about 0.5 and 5.0 feet per second to maintain the coke solids in a dense turbulent lluidized condition. The ilue gases leaving the dense fluidized bed contain entrained solids and the lue gases are passed through cyclone separating means 146 arranged in the upper portion of burner vessel 122 and having an inlet 14S and dipleg 150 for returning separated solids to the dense fluidized bed 136. The cyclone separating means is shown diagrammatically as a single cyclone separator but preferably a plurality of cyclones is used.

The burner vessel 122 is maintained under a superatmospheric pressure of about 5 to 100 p.s.i.g. and the separated flue gas leaving the cyclone separating means 146 through line 151 is passed through a gas turbine 152 and exits to the atmosphere from the turbine 152 through line 154. The i'lue gas from turbine 152 may be passed to a waste heat boiler (not shown) to recover heat therefrom. The turbine 152 is attached or connected by a line diagrammatically shown at 156 to air compressor 158 provided with air inlet 160 for compressing the air and passing compressed air through line 162 and line 163 to the burner vessel 122. Some of the compressed air is passed through line 132 to line 134 where it is used to transfer coke from the reactor 28 to the burner 122. The turbine and compressor are shown as arranged on top of the burner vessel 122 but may be otherwise arranged. By having the burner vessel 122 under increased superatmospheric pressure, the overall burner height is reduced.

AThe present invention is tied in closely with the use of the waste gas turbine 152 to supply combustion air in line 163. This is because the incremental heat duty required for crude oil reduction or treatment can now be supplied from the burner 122 economicaly, whereas in the earlier coker design the incremental operating cost for the air blower would have been prohibitive. The waste gas turbine operation is self-sustaining and produces large volumes of incremental air for very small incremental investment and operating costs. The turbine produces all the compressed air necessary to be supplied to the burner 122 and to line 134.

More coke is produced in the coking process than is utilized in supplying heat to the coker vessel 22 and hence some coke product is removed from the unit. One method of doing this is to withdraw coke particles from the bottom of the vessel 122 through line 166 wd pass the solids to a quench elutriator vessel 168 into which liquid water is introduced through line 170 to quench the coked product and also to elutriate out the coke fines which are removed from the quench elutriator as a steam suspension through line 172 and returned to the dense fluidized bed 136 in the burner vessel 122. The cooled coke product is withdrawn through line 174.

The present invention is distinguished from conventional fluid coking in that a whole petroleum crude oil is used as the feed to the scrubber section 12 and additional heat must be supplied to the scrubber section to vaporize and fractionate the major portion of the crude oil feed. This is done by introducing one or more sprays of liquid such as water or hydrocarbon liquid into the reactorthrough line to vaporize the liquid and to utilize the steam or vaporizehydrocarbonvas aheatcarrier to carry heat from the cokervessel 22 to the scrubber section 12. Any conventionalspray nozzlesmay be used for introducing the liquid into the uid-bed 28. Additional heat is supplied to the Coker vessel 22towsupply the heat of vaporization of the liquid by burning more coke in the burner vesselr122 and circulating more, coke between the Coker vessel 22 and the burner vessel 122.

The additional air required for burning more coke in the burner vessel 122 is supplied by using turbine 152 and compressor 15S.

In the conventional coking system for a 5,000 b./d. of oil feed about 5,000 to 10,000 pounds per hour 0f steam are added to the coking vessel 22 through lines 114 and 116,' but with the lpresent invention when using water as a heat carrier introduced through line 120, about 3,000 to 20,000 pounds per hour of water are used in addition to the steamadded through lines 114 and 116.

In theconventional coking unit about 4 to 8% of gross coke is burned to provide heat for coking whereas in the present invention about 5 to 12% of gross coke is burned.

Much of the additional heat supplied to scrubber section 12 will ultimately be Withdrawn on the fractionation side as net steam product generated by exchanging fractionator pumparound or withdrawn streams with boiler feed water in heat exchangers 60 and 74.

With the present invention it is not necessary to use an atmospheric pipe still or a vacuum pipe still and a single process unit isk provided whichris much cheaper than the conventional unitrequiring either or both of such pipe stills. Whiledwater is givenas one liquid to be used as a heat carrier and as introduced through line 120, a hydrocarbon liquid such as gas oil is preferred because of the higher level latent heat recovered upon condensing higher boiling liquids.

When using water as a heat carrier, it is not necessary to use distilled or pretreated water as in usualboiler water practice, but untreated water such as river water may be used, as any minerals .contained in the water deposit on the Huid coke particles and there are no deposits on boiler tubes to contend with. By using either steam or hydrocarbon vapors in the scrubber section 12, an additional advantage is obtained in that the hydrocarbon partial pressure is reduced in the scrubber section and this irnproves fractionation and separation of desiredV hydrocarbons.

In addition to the advantages set forth there are additional advantages and features of the invention. In the first place with the particular arrangement a lower metals content gas oil is produced. This is accomplished by the mixing of aromatic high boiling coker products in the scrubber section. These aromatics have an affinity for the metal containing hydrocarbon complexes and extract these complexes from the virgin gas oil. The complexes are returned to the coker in the recycle stream where many are depositedgon the coke. Also combined virgin naphtha and coker naphtha and distillate streams are more susceptible for treating and finishing operations. Coker distillate products are highly unsaturated. Treating operations which tend to saturate the coker produc-ts are ditlicult to control because of the temperature rise caused by the large amount of heat released. Mixing the coker products with large volumes of saturated material provides a heat absorbent to reduce the temperature rise caused by heat release. In addition the high steam rates used in the coker vessel 22 reduce the severity of cracking in the coker vessel and produce lower coke yields.

Fora coking unit capable of processing about 30,000 b./d. of whole petroleum crude oil having an API gravity Z of about 34, Conradson carbon of about 7.0 weight percent, and about 77 volume percent distilled at 1000 F. The following conditions are given for carrying out the process of the present invention.

Operating conditions (reactor):

Temperature in reactor 22 F 950 Top outlet pressure np.s.i.g Weight of solids in reactor 22 tons 120 Gas velocity in reactor 22 ft/sec 3.5 Weight of oil feed to coker per hour per weight of solids in coker 0.6 Amount attrition steam to conical section 118 through line 116 #/hr 11,000 Velocity of attriting gas from line 114 ft./sec 3,000 Amount of stripping steam to stripper 110 through line 114 ii/hr- 8,700 Amount of water added to reactor through line 120 t/hr-- 13,500

Operating conditions (scrubber and fractionator):

Bottom temperature of scrubber 12 F-- 750 Bottom temperature of fractionator 31 F 630 Top temperature of fractionator 31 F 220 Temperature light gas oil in line 70. F-- 415 Amount of reduced crude feed to reactor 22 through

lines

102, 104 and 106 b./d 10,000 Temperature of heavy gas oil reflux to top of scrubber 12 through line 54 F 400 And quantity of heavy gas oil refluxb./d 6,000 Temperature of light gas oil reflux in line 76 F 370 And quantity of light gas oil reuX b./d 130,000 Operating conditions (burner 122):

Temperature F-- 1,100 Top pressure p.s.i.g Solids holdup in burner 50T Air ow to burner, standard cubic feet per min. 27,000

Under the above set of conditions the process should yield about 11,000 b./d. of cracked and virgin naphtha having an API gravity of 55 and a iinal boiling point of about 430 F.; about 8,000 b./d. of heavy gas oil having API gravity of 25, and a boiling range of about 650 F. to `850 F.; about 7,500 b./d. of light gas oil having an API gravity of about 35 and a boiling range between about 430 F. and 650 F.; about 5.4 million cubic feet of wet gas per day having an average molecular weight of about 28; and about 340 tons of excess coke per day. About 40,000 #/hr. of steam collected in steam drum 64 under a pressure of about 125 p.s.i.g.

The following is an economic comparison between two cases.

Case 1 (Commercial unit) About 30,000 b./d. of whole crude petroleum oil passed to an atmospheric still where about 50% by volume is distilled olf and then passed to a vacuum pipe still where an additional 17% by volume on the crude is removed overhead. The amount of coker feed is about 10,000 b./d. The investment for Case I is about 5.3 millions of dollars.

Case II (This invention) About 30,000 b./d. of whole crude petroleum oil feed are sent directly to the scrubber section 12 to be vaporized and produce about 10,000 b./d. reduced crude oil feed to the coker reactor 22. The investment for Case II is 4.0 millions of dollars. The savings between Case I and Case II are about 1.3 millions of dollars or about The savings come about by elimination of the vacuum pipe still ($900,000) and the elimination of the atmospheric still ($400,000). There is a further saving in manpower, maintenance costs and in utilities. Also there is a saving in depreciation due to the lower investment. These further savings offset the cost of waste gas turbine.

What is claimed is:

1. In a process wherein heavy hydrocarbon oil is thermally cracked to lower boiling hydrocarbons and coke in a dense lluidized bed of solid particles in a single coking zone and heat is supplied to said cracking step by burning part of the coke solids in a burning zone and returning the heated solids to said cracking step in said single coking zone, the improvement which comprises passing hot cracked gaseous product directly from said cracking step to a scrubbing zone, introducing an oil consisting essentially of a whole petroleum crude oil feed into said scrubbing zone for contacting said whole crude oil feed and said cracked gaseous product to scrub out entrained solids from said feed into said cracked gaseous product and to condense heavy hydrocarbons from said cracked gaseous product and to vaporize lower boiling hydrocarbons from said whole crude oil feed, introducing a uidizing gas into the bottom portion of said dense fluidized bed to maintain the solid particles in a iluidized condition, removing a bottoms fraction from said scrubbing zone and utilizing at least part thereof as the oil feed to said dense uidized bed, and providing additional heat for the distillation of said whole crude oil feed in said scrubbing zone by supplying more heated solid particles from said burning zone and more heat to said dense iluidized bed in said cracking step than is necessary for cracking said oil feed and introducing a vaporizable liquid in addition to said oil feed into said dense uidized bed for vaporizing said liquid and for heating the formed vapors and passing the heated vapors to said scrubbing zone to supply heat thereto for the vaporization of lower boiling hydrocarbons from said whole crude oil feed.

2. In a process wherein heavy hydrocarbon oil is thermally cracked to lower boiling hydrocarbons and coke in a dense uidized bed of coke particles in a coking zone and heat is supplied to said cracking step by burning part of the coke solids in a burner zone and returning the heated solids to said coking zone and steam is supplied to said coking zone as a liuidizing gas for the solids bed therein and cracked vapors are passed directly into the lower portion of a scrubbing zone, the improvement which comprises feeding an oil consisting essentially of a whole petroleum crude oil to an intermediate p0rtion of said scrubbing zone, removing light gaseous material overhead, removing a bottoms fraction from said scrubbing zone, and passing a major portion of said withdrawn bottoms fraction to said coking zone as oil feed and providing more heat in said coking zone than is necessary for cracking said oil feed and utilizing said additional heat for distilling said whole crude oil in said scrubbing zone, removing excess heat from said coking zone by introducing a vaporizable liquid in addition to said oil feed into said coking zone and vaporizing said liquid and heating the vapors and passing the so-heated vapors along with cracked vaporous product directly to said scrubbing zone to supply heat thereto for distilling said whole crude oil.

3. In a process wherein heavy hydrocarbon oil is thermally cracked to lower boiling hydrocarbons and coke in a dense iiuidized bed of solid particles in a coking zone and heat is supplied to said cracking step by burning part of the coke solids in a burner zone and returning the heated solids to said coking zone and steam is supplied to said coking zone as a fluidizing gas for the solids in said bed, and cracked vapors are passed from said coking zone directly to the lower portion of a scrubbing zone, the improvement which comprises feeding an oil consisting essentially of a whole petroleum crude oil to an intermediate portion of said scrubbing zone, removing vapors overhead, removing a bottoms fraction from said scrubbing zone, and passing a maior portion of said withdrawn bottoms fraction to said coking zone as oil feed and providing heat in said coking zone in excess of that necessary for cracking said oil feed by adding excess coke to said burner zone and using the excess heat for distilling said whole crude oil by supplying an excess of heated coke solids from said burner zone, removing excess heat from said coking zone by introducing a vaporizable liquid in addition to said oil feed into said coking zone and vapon'zing said liquid and heating the vapors, passing the so-heated vapors along with cracked vaporous product directly to said scrubbing zone to supply heat thereto for distilling said whole crude oil.

4. A process according to claim 3 wherein said burner zone is maintained under superatmospheric pressure and ue gas leaving said burner zone is utilized in a gas turbine zone to actuate an air compressor zone and to supply additional air needed to burn excess added coke in said burner zone.

5. A process according to claim 1 wherein the cracked vapors and vaporized virgin hydrocarbons from said whole crude are fractionated to separate a bottoms fraction from at least one distillate fraction and heat is removed from certain of said fractionated streams to produce steam to recover some of the heat used in vaporizing the whole crude oil.

6. In a process as defined in claim 1 wherein said vaporizable liquid comprises a hydrocarbon liquid.

7. A process according to claim 1 wherein said vaporizable liquid comprises water to form steam as a heat carrier for carrying heat from said coking zone directly to said scrubbing zone.

8. A method according to claim 1 wherein said uidizing gas comprises steam and the vaporizable liquid comprises water to form additional steam as a heat carrier for carrying heat from said coking zone directly to said scrubbing zone.

9. A method according to claim 3 wherein the vaporizable liquid comprises Water to form additional steam as a heat carrier for carrying heat from said coking zone directly to said scrubbing zone.

References Cited in the le of this patent UNITED STATES PATENTS 2,853,434 Moser Sept. 23, 1958 2,879,221 Brown Mar. 24, 1959 2,895,896 Vander Ploeg r July 21, 1959 2,948,670 Bray et al Aug. 9, 1960 2,963,418 Weinberg et al Dec. 6, 1960 2,978,521 Braconier et al Apr. 4, 1961

Claims

1. IN A PROCESS WHEREIN HEAVY HYDROCARBON OIL IS THERMALLY CRACKED TO LOWER BOILING HYDROCARBONS AND COKE IN A DENSE FLUIDIZED BED OF SOLID PARTICLES IN A SINGLE COKING ZONE AND HEAT IS SUPPLIED TO SAID CRACKING STEP BY BURNING PART OF THE COKE SOLIDS IN A BURNING ZONE SAID RETURNING THE HEATED SOLIDS TO SAID CRACKING STEP IN SAID SINGLE COKING ZONE, THE IMPROVEMENT WHICH COMPRISES PASSING HOT CRACKED GASEOUS PRODUCT DIRECTLY FROM SAID CRACKING STEP TO A SCRUBBING ZONE, INTRODUCING AN OIL CONSISTING ESSENTIALLY OF A WHOLE PETROLEUM CRUDE OIL FEED INTO SAID SCRUBBING ZONE FOR CONTACTING SAID WHOLE CRUDE OIL FEED AND SAID CRACKED GASEOUS PRODUCT TO SCRUB OUT ENTRAINED SOLIDS FROM SAID FEED INTO SAID CRACKED GASEOUS PRODUCT AND TO CONDOME HEAVY HYDROCARBONS FROM SAID CRACKED GASEOUS PRODUCT TO A VAPORIZE LOWER BOILING HYDROCARBONS FROM SAID WHOLE CRUDE OIL FEED, INTRODUCING A FLUIDIZING GAS INTO THE BOTTOM PORTION OF SAID DENSE FLUIDIZED BED TO MAINTAIN THE SOLID PARTICLES IN A FLUIDIZED CONDITION, REMOVING A BOTTOM FRACTION FROM SAID SCRUBBING ZONE AND UTILIZING AT LEAST PART THEREOF AS THE OIL FEED TO SAID DENSE FLUIDIZED BED, AND PROVIDING ADDITIONAL HEAT FOR THE DISTILATION OF SAID WHOLE CRUDE OIL FEED IN SAID SCRUBBING ZONE BY APPLYING MORE HEATED SOLID PARTICLES FROM SAID BURNING ZONE AND MORE HEAT TO SAID DENSE FLUIDIZED BED IN SAID CRACKING STEP THAN IS NECESSARY FOR CRACKING SAID OIL FEED AND INTRODUCING A VAPORIZING LIQUID IN ADDITION TO SAID OIL FEED INTO SAID DENSE FLUIDIZED BED FOR VAPORIZING SAID LIQUID AND FOR HEATING THE FORMED VAPORS AND PASSING THE HEATED VAPORS TO SAID SCRUBBING ZONE TO SUPPLY HEAT THEETO FOR THE VAPORIZATION OF LOWER BOILING HYDROCARBONS FROM SAID WHOLE CRUDE OIL FEED.