US3259565A - Fluidized bed coking process - Google Patents

Description

y 1966 c. N. KIMBERLIN, JR 3,259,565

FLUIDIZED BED COKING PROCESS 2 SheetsSheet 1 Filed March 26, 1963 GASEOUS PRODUCT BURNER FIG-I July 5, 1966 c. KIMBERLIN, JR 3,

FLUIDIZED BED COKING PROCESS Filed March 26, 1963 2 Sheets-Sheet 2 Charles Newton Kimberlin, Jr. Inventor United States Patent 3,259,565 FLUIDIZED BED COKING PROCESS Charles Newton Kimberlin, Jr., Baton Rouge, 1.21., as-

signor to Esso Research and Engineering Company, a corporation of Delaware Filed Mar. 26, 1963, Ser. No. 267,990 Claims. (Cl. 208-127) This invention relates to the thermal conversion of hydrocarbons to produce lower boiling hydrocarbons and choke. More particularly the invention relates to a fluid solids cracking process wherein larger sizes of coke particles are produced and withdrawn from the process than in the known fluid coking process.

In one form of the invention heavy hydrocarbon oil such as residual oil is coked in a fluid bed and the process is carried out to produce lumps of coke of a size suitable for use. in the preparation of electrodes or carbon blocks or the like.

In another form of the invention liquid hydrocarbons are converted to lower boiling hydrocarbons including aromatic hydrocarbons and large particle size coke in a high temperature fluid bed preferably heated electrically.

The known fluid coking process has several advantages over alternate coking processes. One characteristic of the fluid coking process is that the coke produced is in the form of fine particles of fairly narrow size range. For certain uses such as electrode manufacture or in the manufacture of carbon blocks and structural forms or the like, a wider particle size range including sizes up to about /2 inch is desired. The present invention provides a modification of the fluid coking process which produces a part or all of the coke product in the form of lumps. In addition the invention provides certain heat economies and avoids the problems of coking in the outlet lines that are encountered in the usual known fluid cokers.

The fluid coking process can also be used to convert hydrocarbon gas, liquid hydrocarbons and distillates into fuel gas, olefins, aromatic hydrocarbons and coke by thermal conversion at a temperature higher than the usual coking process wherein the heat is supplied by burning some of the coke or by electrical resistance of the coke particles in the fluid coking bed.

The step of forming relatively large lumps of coke includes passing coke granules or lumps or pebbles downwardly through the dilute phase in the coking reactor and then down through the fluid bed in the coking reactor. In passing through the dilute phase the coke lumps contact the coker overhead, cooling (it and condensing heavy ends which are further coked as the coke lumps or pebbles pass down through the fluid coker bed. Also coke fines in the upflowing coker products stick to the downflowing coke lumps and in this way the size of the lumps increases.

In the other form of the invention where higher temperatures are used to produce gas, benzene, naphthalene, etc., and large particle size coke such as lumps or pebbles, the heat of conversion or coking is preferably by electrical resistance of the coke bed. In prior art processes using high temperatures above about 1300 F., the heat economy is poor since the gaseous conversion products are withdrawn at substantially the same temperature as the fluid bed and the coke product is in the form of finely divided solids of a fairly narrow particle size range, whereas many coke uses or applications require a broader size range containing some larger particles in the 3,259,565 Patented July 5, 1966 form of lumps or pebbles. The present invention provides steps for overcoming these disadvantages.

In the drawings:

FIG. 1 represents one form of apparatus for carrying out a fluid coking process at conventional temperatures wherein coke lumps or pebbles of up to about 1 /2 inches are formed and can be withdrawn from the process; and

FIG. 2 represents a modified form of apparatus for fluid coking at higher temperatures to form unsaturated gases, aromatic hydrocarbons and coke lumps or pebbles.

Referring now to the drawings, the reference character 10 designates a vertically arranged coking reactor which is cylindrical but which may be of any shape and has a funnel shaped bottom 12 leading to a depending elutriator and heat exchange zone -14. Reactor 10 contains a dense fluid bed 16 of coke having a level indicated at 18 with a dilute phase 22 thereabove. Steam or other elutriating gas is introduced into the lower portion of elutriator 14 through one or more lines 24. Water may also be introduced through line 24 to provide cooling of the coke pebbles in zone 14. Hydrocarbon oil feed such as residual petroleum oil boiling above about 750 F. and preferably preheated is introducedinto the coke fluid bed 16 through line 26.

The bottom portion of elutriator zone or section 14 is swaged down or funnelled down at 28 to a smaller cylindrical vertically arranged pipe 32 for removing coke lumps or coke pebbles from the bottom of elutriator zone 14 for recirculation in the system as will be hereinafter described. Steam or other gas is introduced into the bottom portion of pipe 32 through line 34 for upward pas sage through pipe 32 to strip out fine coke particles from the coke lumps and return the fines to reactor 10 and also *to cool the coke pebbles in elutriator 14.

The oil feed in line 26 may be residual petroleum oil or other heavy oils such as heavy crude oils, atmospheric and vacuum crude oil bottoms, pitch asphalt, etc., or mixtures thereof. The coke particles in the fluidized bed '16 have an average size between about 35 and 2000 microns in diameter with preferably not more than about 5% having a particle size below microns. The temperature of the fluid bed 16 in the reactor '10 is between about 850 -F. and 1000 F. In the conventional fluid bed coking process about 10 to 25 wt. percent of the oil feed forms coke product which is withdrawn from the process through line 36 leading from the bottom portion of fluid bed 16 from funnel section 12. The top of elutriator zone 14 is at the same temperature as fluid bed '16 :and at a temperature between about 400 F. and 850 F. at the bottom.

The coke lumps or pebbles 37 of a size between about A; and 1% inches added as such as the beginning of the process or formed during coking in the fluid bed pass down through pipe 32 having a valve or star feeder 38 into riser or vertically arranged line 42 into which steam or other gas is introduced through line 44 to form a steam or gas lift for .the pebbles 37 land empties them into a vertically arranged hopper 46. Hopper 46 has top gaseous outlet line 48 and a funnel shaped bottom 52 leading to a restricted vertically arranged line or pipe 54 leading to a heat exchange and lump coke growth zone or vessel 56. The coke lumps or pebbles in pipe 32 are at a temperature between about 700 1F. and 950 The coke particles forming the lumps increase in size as they are recirculated many times through the system via line 4-2.

The vessel 5( is vertically arranged having an inverted funnel shaped upper end 58 and a funnel shaped bottom portion 62 Which extends into and communicates with dilute phase 22 of vessel 10. The bottom end of funnel 62 has an opening of about the same diameter as pipe '54. The coke lumps or pebbles are lifted [through riser 42 to hopper 46 from which they pass down through line 54 and as a moving bed through lump coke growth zone or vessel 56 and then down through funnel 62 into dilute phase 22 in vessel '10 and then into and down through fluid bed 16. The heat exchange vessel 56 is at a temperature between about 700 F. and 950 F. at .the top and between about 850 and 1000 F. at the bottom. Coke particles or lumps of a size larger than about 3000 microns are not fluidized in fluid coking bed 16 and pass down through the bed. These coke particles grow in size as they pass through vessels 56 and as they are recirculated many times through this cycle. Coke fines in dilute phase 22 of reactor 10 stick to the downflowing coke lumps .to increase the size of the coke lumps being circulated. The coke lumps are circulated many times through vessel .56, dilute phase 22 in reactor 10, fluid bed 16, heat exchange zone 14, standpipe 32, recycle line or riser 42 to hopper 46 and then to vessel 56 again and grow in size as described.

The hot vaporous coked products pass from fluid bed 16 into dilute phase 22 and up through heat exchange and lump coke growth vessel or section 56 where the coke lumps or pellets are at a lower temperature than the hot vaporous coked products so that the coke lumps cool the overhead coker vapors condensing the heavy ends or higher boiling constituents therefrom and returning the .coke lumps or pellets to the fluid bed 16 in coke reactor 10 to coke the deposited heavy ends. The cooled coker vaporous products pass up through heat exchange zone 56 and are withdrawn through top outlet line 64 leading from the upper portion of heat exchange zone '56 and are further treated as desired to recover rnotor fuel, gas oil, etc.

The coke lumps in growth zone or vessel 56 grow in size by two mechanisms: (ll) by coke lay-down through the coking thereon of part of the heavy ends, and (2) by aggregation or accumulation of coke fines carried up from the fluid bed 16 in zone 10 into dilute phase 22 and heat exchange zone 56. Coke lumps or pebbles of a size between about /s and 1%. inches in size preferably between about A and of an inch in size are withdrawn from the process as product through valved line 65 from the lower portion of elutriator section 14.

The coke lumps pass down through heat exchanger and coke elutriator section or vessel 14 and preheat the process steam introduced through line 24 and which passes up through fluid coking bed 16. The coke lumps are cooled to (the desired temperature for reintroduction into the top of heat exchange coke growth zone or vessel 56. The coke lumps are cooled to a temperature between about 400 and 850 F. depending on the cut point desired for the overhead vaporous coker product leaving vessel 10. The coke growth vessel 56 recovers heat from the vaporous coker products and avoids coking in the cyclone separators and outlet lines which is encountered in the usual fluid coking units.

Heat for coking is provided by withdrawing fine coke particles from the fluid bed 16 through standpipe 66 or the like. Air is introduced into the withdrawn coke particles through line 68 and the mixture passed through riser '72 into the lower portion of vertically arranged burner vessel 74 where the coke particles are partially burned in fluid bed '76 having a level indicated at 78. The coke particles are heated to a temperature of about 100 F. to 300 F. above the temperature of the fluid bed 16 in coker reactor 10. The fluid bed 76 in burner 74 is at a temperature between about 1050 F. and 1200 F. The heated coke particles are returned to the fluid bed 16 through standpipe 82 diagrammatically shown as returning the heated coke particles to the lower portion of fluid bed 16 in reactor 10.

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Burned vessel 74 is provided with internal cyclone 84 for removing coke particles from combution gases leaving vessel 74. The cyclone separator has dip leg 86 for returning separted coke particules to fluid bed 76 and a top outlet 88 for removing combustion gases.

A target may be installed in hopper 46, if desired, to cause a certain amount of breakage of coke lumps to cotrol their number and size, or alternatively other means may be used to provide smaller coke lumps to serve as nuclei for growth.

Referring now to FIG. 2 of the drawings, the apparatus shown is also adapted for producing coke lumps or pebbles in a fluid coking process but in this form, higher temperatures of coking are used, different oil feeds may be used and electrical resistance heating is provided for the coking step so that a separate heating vessel is eliminated.

It has been proposed to convert various feeds such as liquefied petroleum gas, light naphtha, heavy naphtha, kerosene, heating oil, gas oil, etc., into fuel gas (town gas), ethylene, benzene, naphthalene, etc., and coke by thermal conversion at about 1400l600 F. in a fluid bed of coke wherein heat is supplied by electrical resistance of the coke bed. At higher temperatures, in the range of 1800 to 2200 F. the products of this process are coke and hydrogen containing very small amounts of methane and other hydrocarbons. The purity of the hydrogen product in this modification of the process is 90 mole percent or more. While, in general, this is an excellent process, it suffers from two serious disadvantages: (1) the heat economy is poor since the gaseous products are withdrawn at the same temperature as the fluid bed and (2). the coke product is in the -form of finely divided solids of a fairly narrow particle size range, whereas many coke applications require a broader size range containing some larger particles. The present invention provides a method for overcoming these disadvantages.

The process is similar to that described in connection with FIG. 1 except that heat is supplied to the fluid bed 92 in heating vessel 94 by electrical resistance of the coke particles. A positive electrode 96 and a negative electrode 98 are diagrammatically shown for heating the fluid bed to atemperature between about 1300 F. and 2200 F. More than one set of electrodes is preferably used. Direct or alternating current may be used. When using fluid coke as the fluid bed a voltage of about 3 to 10 volts per inch distance between the electrodes is preferably employed but the voltage may be chosen from 0.1 to 1000 volts per inch. Coke pebbles of a size between about /s and 1 /2 inches, preferably about to inch pass down through fiuid bed 92 in heating vessel 94 and become heated to the temperature of fluid bed 92.

Heating vessel 94 is vertically arranged and has a funnel shaped bottom 102 which has opening 104 which empties into a vertically arranged reaction zone or vessel 106 which has a smaller diameter than vessel 94 and which depends therefrom. Vessel 106 comprises a reaction zone through which a downwardly moving compact non-fluid bed 107 of coke lumps or pebbles moves. The coke lumps pass from heating vessel 94 to the top of reactor or coking vessel 106.

Vaporized or partially vaporized oil feed is passed into coking vessel 106 through bottom line108 which leads into the bottom portion of reaction vessel 106 and the oil vapors flow up countercurrently to the downwardly moving bed 107 of coke lumps or pebbless The oil feed becomes heated and cracks as the vapors flow up countercurrent to the downwardly moving bed of coke lumps or pebbles. The oil feed vapors crack in the middle and upper portions of reaction zone 106 depositing additional coke on to the coke lumps or pebbles causing the lumps to grow in size. The upper or top portion of moving bed reactor 106 is at a higher temperature than the lower portion of reactor 106. The upper portion of the bed 107 in reactor 106 is at a temperature between about 1300 F. and 2200 F. and the bottom portion of the bed 107 in reactor 106 is between about 400 F. and 1000 F.

It is desirable that the oil feed enter the reaction zone or vessel 106 at a temperature not much in excess of its vaporization temperature in order to extract as much heat as possible from the coke pebbles in reaction zone 106. In cases where it is desirable to employ an oil feed having a wide boiling range or a mixedoil feed such as light naphtha plus gas oil it is preferred to introduce the lighter portion of the feed near the bottom of reaction zone 106 through line 108 and the heavier portion of the oil feed at a higher level such as through line 112.

The vaporized oil feed flowing upwardly through reaction zone 106 is substantially converted in the upper portion of zone or vessel 106. The cracked vaporous products pass overhead from vessel 106 and pass up through heating vessel 94 wherein some additional conversion occurs and the vaporous cracked products leave fluid bed 92, pass up through dilute phase 114 into heat exchange zone 116 where the vaporous cracked products are cooled by the downwardly moving non-fluid bed 117 of coke pebbles therein and are finally removed from the system overhead from heat exchange zone 116 through line 118. In the heat exchange zone as in the process described in connection with FIG. 1, some of the heavy ends or higher boiling hydrocarbons in the vaporous cracked products are condensed and partially coked on the coke lumps or pebbles to cause the pebbles to grow. The upfiowing vapors in reactor 106 also act to elutriate coke fines from reactor 106. Further coking of the heavy ends takes place in the reactor 106 as the coke lumps or pebbles move down therethrough. The coke lumps or pebbles increase in size as they are circulated many times through heat exchanger vessel 116, dilute phase 114 in vessel 94, fluid bed 92 and reactor 106.

The flow of coke pebbles through heat exchanger vessel or zone 116 may be controlled or regulated by a valve arrangement which has a valve head 122 at its lower end which cooperates with the funnel shaped bottom 124 of heat exchange zone 116 to control the size of the valve opening 126. Valve head 122 is connected to valve stem 128 which extends up through stufling box 132 at the top of zone 116. Other means of regulating the flow through heat exchanger zone 116 may be employed, if desired. The temperature in the upper part of zone 116 is between about 400 F. and 1000 F.

Coke lumps or pebbles may be withdrawn from the process as product through line 134 from heat exchange zone 116 or through line 136 from reaction zone 106.

As in FIG. 1 coke lumps or pebbles pass down through vertical pipe 138 having control means 140, lifting gas is introduced through line 142 to lift the coke lumps or pebbles through riser 144 to hopper 146 from which the coke lumps or pebbles pass through line 148 to heat exchanger zone 116. If desired, elutriation gas may be introduced at the bottom of pipe 138 through line 149. Carrier gas passes overhead from hopper 146 through line 150. Fluid coke formed in the process is withdrawn from vessel 94 through line 160. More coke for a given quantity of feed is recovered than in the process of FIG. 1 because coke is not burned to supply heat of coking.

From heat exchange zone 116 the coke lumps or pebbles pass down through valve opening 126 and pass through dilute phase 114 in vessel 94 and here coke fines in the dilute phase stick to the lumps or pebbles to increase the size of the coke lumps or pebbles.

As a modification in FIG. 2 the heat exchange zone 116 may be arranged or disposed at an angle or even horizontally in which case the flow of coke lumps or pebbles through heat exchange zone 116 may be controlled by a solids pump or ram such as has been used to feed an upflow shale retort.

In a simplified form of the invention in FIG. 2, the heat exchange zone 116 may be omitted and the hopper 146 may feed the coke lumps or pebbles directly into the upper portion of heating vessel 94. However, this arrangement does not provide for the excellent heat economy that is achieved when using heat exchange zone 116.

In a specific example in connection with FIG. 1, the oil feed comprises -a residual petroleum oil having an initial boiling point above about 850 F., and about 4000 barrels per day are passed through line 26 at a temperature of about 500 F. intocoking fluid bed 16 maintained at a temperature of about 965 F. Reactor 10 is about 11 feet in diameter and contains about 70 tons of fluid coke in bed 16. The fluid coke particles forming the bed 16 are between about 75 and 2000 microns in size. About 150,000 pounds of water and 75,000 pounds of steam per day at a temperature of about 212 F. are introduced through line 24 into elutriating and heat exchange zone 14 to remove fine coke particles from the downwardly moving coke lumps or pebbles and to furnish cooling for the coke pebbles in zone 14. The bottom of the heat exchange zone 14 is at a temperature of about 450 F.

The coke lumps or pebbles formed in the process which are of a size of about /8 to 1 /2 inches are recirculated through the system. About tons per day of lump coke having a size of about Ms to 1% inches are withdrawn through line 65.

About 100 tons per day of fluid coke having a size between about 75 and 2000 microns are withdrawn from coking vessel 10 through line 36.

About 500 tons per day of coke lumps of a size of between about 4; and 1% inches are recirculated many times through line 42 to and through hopper 46, through heat exchange and coke lump coke growth vessel 56, and through dilute phase 22 in reactor 10 and fluid bed 16 in reactor 10. About 25,000 pounds per day of steam at a temperature of about 350 F. are passed through line 44 to lift the coke lumps being recirculated through line 42. 1

The gaseous product taken overhead through line 64 comprises the following:

98,000 pounds of C minus gas per day. 280,000 pounds 0 -430" F. hydrocarbon per day. 622,000 pounds 430 F. plus hydrocarbon per day.

The bottom portion of heat exchange zone 56 is about 965 F. and the top portion of heat exchange zone or vessel 56 is about 850 F.

The burner vessel fluid bed 76 is maintained at about 1150 F. and about 6500 tons of coke per day are recycled to coker vessel 10 through line 82. Burner vessel is about 12 feet in diameter and contains about 22 tons of fluid coke.

In the normal operation of fluid coking units the heat supplied by hot coke particles from the burner 74 vaporizes the volatile portions of the heavy oil feed and thermally cracks or cokes the higher boiling unvaporizable portions of the oil feed, forming new deposits or layers of coke on the original coke particles in the coker fluid bed, so that in the normal operation of the coking process there is coke particle size growth but if this is permitted to go on, the coke particles become too large to form a fluid bed and fluidization problems arise.

The present invention provides a modified fluid coking process which maintains a fluid bed for coking hydrocarbon oils and also forms coke agglomerates or lumps of a size above about 414 /2 inches which are withdrawn as product after the coke lumps have been recirculated through the system a sufficient number of times to form the coke lumps of desired size.

The modification shown in FIG. 2 operates at a higher temperature to produce olefins, fuel gas, aromatic hydrocarbons and coke both fine and in lump or agglomerate form. In this modification preferably electric resistance heating of the fluid coke bed 92 in the vessel 94 is used so that a separate burner vessel is eliminated.

The fluid bed 92 is maintained at about 1500 F. About 2000 barrels per day of naphtha having a boiling range of about 200 F. to 430 F. are introduced through line 108 into the bottom portion of reactor 106 at a temperature not much in excess of its vaporization temperature in order to recover heat from the coke lumps in reactor 106.

The bottom portion of reactor 106 near inlet feed line 108 is about 500 F. and the oil feed in line 108 is about 400 F. The upper portion of reactor 106 near the opening 104 is about 1500 F.

The vessel 94 is about 12 feet in diameter and contains about 75 tons of fluid coke having a particle size between about 75 and 1000 microns.

The products withdrawn through line 118 comprise per day:

10,800 pounds of hydrogen.

186,000 pounds of methane 36,00 pounds of ethylene 18,000 pounds of ethane 3,000 pounds of C hydrocarbons 240 pounds of butadiene 34,600 pounds of benzene 9,000 pounds of toluene 6,000 pounds of C plus aromatic tar.

The temperature of the bottom portion of moving bed 117 near valve opening 126 is about 1450 F. and the temperature of moving bed 117 near gaseous outlet line 118 is about 500 F.

About 90,000 pounds of finely divided coke below about 1000 microns in size are withdrawn as product from fluid bed 92 through line 160.

About 210,000 pounds of coke agglomerates or lumps of a size between about A; and 1% inches are withdrawn as product through line 136.

What is claimed is:

1. A process for converting hydrocarbons to produce lower boiling hydrocarbons and solid coke particles of a size larger than fluidizable size which comprises passing coke agglomerates down through a hot fluidized bed of coke particles, introducing hydrocarbon oil feed into said fluidized bed to crack the hydrocarbon oil, passing cracked vaporous products overhead, removing coke agglomerates from said fluid bed and passing them down through a heat exchanger zone in countercurrent contact with said withdrawn cracked vaporous products to cool said cracked vaporous products and to heat said coke agglomerates while condensing and depositing higher boiling hydrocarbons from said cracked vaporous products on said coke agglomerates, withdrawing resulting cracked vaporous products as product, recirculating the so treated coke agglomerates a number of times through said heat exchange zone to deposit hydrocarbons and through said hot fluidized coke bed to coke the deposited high boiling hydrocarbons and to increase the size of the coke agglomerates, withdrawing coke agglomerates of increased size as product from the system.

2. A process of converting hydrocarbons which comprises providing a hot fluidized bed of coke particles, introducing hydrocarbon feed into said fluid bed to crack said feed, circulating larger non-fluidizable coke particles through said fluid bed a number of times, separating said hot larger coke particles from said fluid bed and passing them down as a compact non-fluidized bed through a heat exchange zone in countercurrent relation to upflowing cracked vaporous products withdrawn from above said fluid bed to heat said larger coke particles and cool said cracked vaporous product and condense higher boiling hydrocarbons therefrom and deposit condensed hydrocarbons on said larger coke particles, continuing the recirculation of said larger non-fluidizable coke particles a number of times through said fluid bed and said heat exchange zone until the desired coke agglomerate sizes are obtained and withdrawing from the process converted hydrocarbons and enlarged coke agglomerates larger than those initially introduced into the process.

3. A process according to claim 2 wherein finely divided coke particles are withdrawn from said fluid bed and passed to a burning zone to heat the coke particles and then recycling the heated coke particles to said fluid bed to supply heat thereto.

4. A process according to claim 2 wherein coke agglomerates are separated from finely divided coke particles from said fluid bed by elutriating finely divided coke particles from said coke agglomerates while cooling said coke agglomerates at the same time and then passing said cooled agglomerates to said heat exchange zone.

5. A process of converting hydrocarbons at a high temperature to produce normally gaseous products, aromatic hydrocarbons and coke which comprises maintaining a hot fluidized bed of finely divided coke at a temperature above about 1200 F., passing non-fluidizable coke lumps formed in said process down through said fluid bed to heat said coke agglomerates, then passing said heated coke agglomerates downwardly as a compact nonfluid bed through a reaction zone, introducing hydrocarbon feed into the lower portion of said non-fluid bed and passing hydrocarbon vapors up through said non-fluid bed in countercurrent flow to crack said hydrocarbon vapors, removing cracked hydrocarbon vapors and passing them upwardly through said fluidized coke bed for further cracking, removing cracked vapors overhead from said fluidized coke bed, removing coke agglomerates from the bottom of said compact non-fluid bed, heat exchanging said removed coke agglomerates with said cracked vapors removed from said fluidized coke bed to cool said cracked vapors and to remove high boiling hydrocarbons therefrom by absorbing them on said coke agglomerates, recovering lower boiling cracked products from said cracked vaporous products, passing the non-fluidizable agglomerates with the absorbed hydrocarbons down through said.

fluidized coke bed to crack and coke the hydrocarbons absorbed on said non-fluidizable agglomerates and repeating the steps of recycling said non-fluidizable agglomerates through said heat exchange, the fluidized coke bed and said reaction zone until the desired sized agglomerates are obtained and withdrawing the enlarged non-fluidizable coke agglomerates from said process as product.

6. A process of cracking a vaporizable hydrocarbon to form unsaturates, aromatic hydrocarbons and coke which comprises maintaining a fluidized coke bed at a temperature above about 1200 F., heating non-fluidizable coke lumps by passing them down through said fluid coke bed, collecting the heated coke lumps and passing them down through a reaction zone as a moving bed, passing hydrocarbon vapors through said reaction zone to crack said vapors, to cool said coke lumps and deposit coke on said coke lumps, passing .cracked vapors from said reaction zone through said fluid coke bed for further cracking of the vapors, withdrawing cooled coke lumps from said reaction zone, passing the resulting cracked vapors in contact with withdrawn cooled coke lumps to remove high boiling material from the cracked vapors by absorption on said coke lumps, recycling the last mentioned coke lumps to said fluid coke bed and said moving bed reaction zone, repeating the recycling of said coke lumps until the size of the coke lumps is greater than about A; of an inch, separating desired hydrocarbons from the cracked vapors and separating the larger sized coke lumps from the process as product.

7. A process according to claim 6 wherein said fluid coke bed is heated by electrical resistance of the coke particles.

8. A process according to claim 6 wherein the fluid bed is maintained at a temperature of about 1800 F. or higher to form coke and hydrogen having a purity of at leastmole percent.

9 10 9. A process according to claim 1 wherein the agglom- References Cited by the Examiner crates withdrawn from the process as product are at least UNITED STATES PATENTS A; of an inch in size and wherein the cracked vaporous products passing overhead from said fluid bed and through g 2 it a said heat exchanger zone contact said agglomerates which 5 2982622 5/1961 Jahnig et accumulate coke fines carried up from said fluidized bed of coke particles to form larger agglomerates. FOREIGN PATENTS 10. A process according to claim 1 wherein the cracked 817,333 7/ 1959 Great Britain.

vaporous products assing overhead from said fluid bed and through said heft exchanger zone contact said agglom- 1O DELBERT GANTZ Primary Exammer' crates which accumulate coke fines carried up from said ALPHONSO SULLIVAN, Examinerfluidized bed of coke particles to form larger agglomerates P P, GARVIN, Assistant Examiner.

Claims (1)

1. A PROCESS FOR CONVERTING HYDROCARBONS TO PRODUCE LOWER BOILING HYDROCARBONS AND SOLID COKE PARTICLES OF A SIZE LARGER THAN FLUIDIZABLE SIZE WHICH COMPRISES PASSING COKE AGGLOMERATES DOWN THROUGH A HOT FLUIDIZED BED OF COKE PARTICLES, INTRODUCING HYDROCARBON OIL, FEED INTO SAID FLUIDIZED BED TO CRACK THE HYDROCARBON OIL, PASSING CRACKED VAPOROUS PRODUCTS OVERHEAD, REMOVING COKE AGGLOMERATES FROM SAID FLUID BED AND PASSING THEM DOWN THROUGH A HEAT EXCHANGER ZONE IN COUNTERCURRENT CONTACT WITH SAID WITHDRAWN CRACKED VAPOROUS PRODUCTS TO COOL SAID CRACKED VAPOROUS PRODUCTS AND TO HEAT SAID COKE AGGLOMERATES WHILE CONDENSING AND DEPOSITING HIGHER BOILING HYDROCARBONS FROM SAID CRACKED VAPOROUS PRODUCTS ON SAID COKE AGGLOMERATES, WITHDRAWING RESULTING CRACKED VAPOROUS PRODUCTS AS PRODUCT, RECIRCULATING THE SO TREATED COKE AGGLOMERATES A NUMBER OF TIMES THROUGH SAID HEAT EXCHANGE ZONE TO DEPOSIT HYDROCARBONS AND THROUGH SAID HOT FLUIZIDED COKE BED TO COKE THE DEPOSITED HIGH BOILING HYDROCARBONS AND TO INCREASE THE SIZE OF THE COKE AGGLOMERATES, WITHDRAWING COKE AGGLOMERATES OF INCREASED SIZE AS PRODUCT FROM THE SYSTEM.

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