US 2694622 A
Description (OCR text may contain errors)
H. C. REED ET AL HYDROCARBON REFINING APPARATUS Original Filed July 2, 1948 Nov. 16, 1954 United States Patent O HYDROCARBGN REI-TIN ING APPARATUS Homer C. Reed, Glendale, and Clyde H. 0. Berg, .Long
Beach, Calif., and Charles B. Lefert,'Library, Pa., assignors to Union Oil Company of California, Los Angeles, Calif., a corporationof California Original application July 2, 1948, Serial No. 36,724. Di-
vided and this application September 3, 1949, Serial No. 114,044
9 Claims. (Cl. 23-260) This invention relates to a process and apparatus for the rening of heavy oils such as crude petroleum, straight run and cracked residuums, .coker distillates, mineral oils such as those recovered from shale, tar sand, diatomite, and miscellaneous .bituminous sands which may or may not be contaminated with undesirable elernents such as nitrogen, oxygen and sulfurcontaining hydrocarbon compounds,.coal oil fractions, particularly those of high density recovered from the distillate produced during coal coking which may be contaminated with acid or basically reacting constituents. for the production of lighter products such as liquids boiling below about 800 F., fractions of which are suitable for fuels in internal combustion `engines and diesel engines, lubricating oils,. solvents, miscellaneous naphthas, and the like. This is a division` of our copending application Serial No. 36,724, led July 2, 1948 now Patent No. 2,614,067.
More particularly this invention relates to refining processes for the conversion of .high density or low A. P. I. gravity oils lto products of lower boiling range and lov/er density which involve coking these oils to form coke and avcoker distillateandhydrogenating the distillate in the presence of water, `and a metal capable of reacting with water to form hydrogen.
The hydrogenation of mineral oils7 and the like, is well known `in the art. Generally this has been accomplished by subjecting the oil to be hydrogenated to temperatures of from 200 F. to about 680 F. and from about l atmosphere to ashigh as about` l0() atmospheres of hydrogen in the presence of ia hydrogenation catalyst usually comprising one. of the. noble'metals such as platinum or palladium, or oxides thereof. The principal dis advantages of such processes include expensive and cornplex hydrogenation equipment, fextensive compression t.
facilities forraising the hydrogen pressure to the level required by the process, expensive, sensitive and easily poisoned catalysts which must beemployed, and the problem of catalyst recovery.
lt is an object of this invention to provide an easily controlled and etcient process fort-he hydrogenation of heavy oils for-'the production of lower boiling fractions.
Another object of this invention is to provide ya process for converting high density oilsfwhich may be contaminated with undesirable constituents to desirablefproducts of lower boiling range and density including the steps of coking the high density oil in the presence of spent solids from the hydrogenation operation, simultaneously regenerating the spent solids and converting the coke to producer gas and employing the regenerated solids in the production of .hydrogen and the simultaneous hydrogenaticn ofthe heavy oil.
Another object of this invention is to provide an improved process for the recovery of elemental sulfur from sulfur contaminated crude petroleum.
A further object of this invention is to provide an improved processp for the reduction of oxides of metals such as iron to lower oxidation states or to their elemental form whichinvolves steps of laying down a layer of eolie on the oxide particles and'reacting the coke-laden oxide at elevated temperatures in a lluidized vessel to produce producer gas and the metal in a nely divided ate.
Another object of this invention'is to provide an improved method for the hydrogenation of heavy oils which comprises reacting a finely dividedvmetal or oxide of a ice metal above hydrogen in the electromotive series ofmetals with water in the presence of the oil to be hydrogenated to form the metal oxide, recovering thef'metal `oxide'frorn the hydrogenated material, laying'down' a layer of'coke on the oxide particles and converting the coke-bearing oxide to the elemental metal or tofa lower oxide for reuse as a hydrogenation catalyst and asa source of hydrogen.
A further object of this invention-isto'provide an improved continuous process for the hydrogenation of oils with hydrogen' produced by the reaction of elemental iron with water or water vapor.
It is also an object of the present invention tot provide an apparatus by which the aforementioned processes may be effected.
Other objects and advantages of this invention will become apparent to those skilled in the art as the description thereof proceeds.
Briefly, the preferred modification of this vinvention comprises the high temperature pyrolysis' of'hydrocarbon oils in the presence of particles of a spentvmetal oxide in a lluidized coking zone whereby a layer of coke is laid down on the particles and `lower boiling hydrocarbon pyrolysis products are formed, separating the coke-laden oxide particles from the pyrolysisproducts, reacting the coke with the spent oxide particles in a fluidized reducing regenerating zone tofforrn regenerated particles, combining a portion of the regenerated particles with at least` apart of the pyrolysis'product, subjecting the mixture thus formed to conditions of superatmospheric temperature andpressure in thepresence of water thereby hydrogenating the pyrolysis product and forming a spent metal-oxide, separatingdesirable fractions of the hydrogenating'product thus formed, recovering the spent oxide and-recycling it'withthe high density oil to be coked.
The process of the present invention eliminates'virtually all of the aforementioned'disadvantagesand employs an inexpensive ruggedcatalyst. The process further utilizes hydrogengenerated under superatmospheric pressure in the presence of the oil to be hydrogenated thereby eliminating the compression facilities usually required for high pressure hydrogenations. .The hydrogen is ygenerated from waterand a metal ora metal compound which also acts as a catalyst. The solids employed are readily recoverableif desired, and such small losses as do occur are notimportant since the material is readily and inexpensively obtained.
In the process of this invention, the solids employed preferably comprise a iinely` divided metal above hydrogen in the electromotive :series of'metals, which may or may not contain aminor quantity of oxides or suldes ofthat metal, and which is also capable of reacting with water for the liberation'of hydrogen. Such metals` as iron, zinc, cobalt, nickel, and the like,.may-be employed, those of atomic number from 25 to 30 beingfsuitable with exception of copper as wellas the lower oxides of these metals. In the preferred modication of the process, finely divided iron of the type generally known as sponge iron, is preferred. Thesematerials are rugged, easily recovered, highly reactive under the conditions of the process, and relatively inexpensive. :The iron particles may be prepared in `a variety of manners, although the preferred method involves the reductionof finely divided iron oxides known as mill scale obtainable from such sources as rolling mills and the like. The solid particles may also bepreparedby the reduction of finely ground and naturally-o`ccurring iron oxides or from other sources.
In the coker, reducing regenerator, and the oxidizing regenerator, uidized suspensions of solids are established in gaseous mixtures in a condition of `hindered settling. The gases move upwardly while the solids slowly settle and a thorough countercurrent contact is effected as well as precise temperature control. The iron serves to decompose water to produce the required hydrogen and also perform as a mild hydrogenation catalyst.
During the hydrogenation step of the .combination process of this invention, the sponge iron catalyst is commingled with the oil to be hydrogenated and a predetermined quantity of water to form a slurry. This slurry is introduced at high pressures through a heater into an agitated hydrogenation vessel. A completely liquid phase reaction occurs at temperatures sufficiently high to effect the reaction of water and elemental iron and which may be as high as to cause further decomposition of the hydrocarbon to be hydrogenated. By carefully controlling the temperature of the hydrogenation, a variable degree of destructive hydrogenation or combined hydrogenation and cracking may be effected in the presence of iron which may also act as a hydrogenation catalyst as well as the source of hydrogen. During this hydrogenation reaction, the iron is converted to iron oxide. Hydrogenated oil. iron oxide, and unreacted water, etc. are introduced into a suitable separating device for recovery of the individual fractions of the mixture. Such a separation may be effected in a conventional fractionating column of the bubble tray type in which hydrocarbon fractions of any desired boiling range may be recovered along with the iron oxide and any residual oil. In such a system, the residual oil contains iron oxide formed in the hydrogenation vessel and this residual fraction is preferably combined with the high density oil to be treated and reprocessed.
Occurring simultaneously with the hydrocarbon h vdrogenation step is an eicient desulfurization by means of Which sulfur compounds are decomposed with the ultimate formation of iron sulfides which are removed with the iron oxides in the residual oil from the hydrogenation product fractionator. The process provides means for separation of iron sulfides from the iron oxides and the oxidation of such sulfides to form sulfur dioxide. The sulfur dioxide is subsequently converted to elemental sulfur by effecting a reaction of sulfur dioxide with carbon monoxide contained in producer gas. The sulfur may be recovered either as a finely divided solid or as a liquid depending on the temperature. lf desirable, this sulfur dioxide may be further oxidized and converted to sulfuric acid.
The nitrogen compounds which may be present in certain types of high density oils to be treated are decomposed under conditions of hydrogenation with the formation of ammonia. Since the hydrogenation is accomplished in the presence of water, the fractionator may be operated under such conditions so that the overhead temperature permits the removal of an aqueous phase containing dissolved ammonia from the upper portion of the column.
The process and apparatus of the present invention may be more clearly understood by reference to the drawing in which a schematic flow diagram of this invention is shown. To further facilitate the description and to also provide a practical operating example of the process, the following description of the drawing will be conducted in the form of an example in which high density crude petroleum produced from the oil fields of Santa Maria Valley (California) is the oil to be treated and in which the catalyst employed is sponge iron. Flow quantities are given and operable ranges of pressure and temperature as well as preferred operating pressures and temperatures are included.
Heavy oil cokz'ng Referring now more particularly to the drawing, 260 barrels per day (42 U. S. gallons per barrel) of Santa Maria Valley (California) crude petroleum amounting to 43.9 tons per day is treated according to the process of this invention. This heavy oil is preferably topped for straight-nin gasoline recovery. The crude petroleum passes via line 10 under pressure exerted by pump 11 through line 12 controlled by valve 13 and is combined with 49 barrels per day of coker residuum recycled through line 14 controlled by valve 1S and with a stream containing 8 tous per day of hydrogenated residuum, 2.76 tons per day of iron sulfide, and 20.9 tons per day of ferrie oxide flowing through line 16 controlled by valve 17. The combined stream is introduced via line 18 into heater 18a wherein it is heated to a temperature of from about 700 F. to as high as about 1200 F. and preferably to about 900 F. The heated stream then passes via line 19 into coker 20 wherein pyrolysis of the hydrocarbons is effected with the formation of hydrocarbon pyrolysis products of lower 4 boiling range and a mixture of iron oxide and iron sulfide particles laden with coke.
Coker 20 is a vessel in which the particles of iron compounds such as higher oxides Fe304 and FezOz are maintained in a uidized state due to the mixing action of hydrocarbon liquid and vapor being introduced from heater 18a. The coke-laden iron compound particles are present in vessel 20 in a state of hindered settling and act much as a high density fluid which accumulates in a lower portion of the vessel. Thus a level 21 exists below which the coke-laden particles are in rapid motion, hindered from settling, and above which the particles tend to settle forming a solid-free gas space. Present within Coker 20 is separator 22 by means of which particles of suspended iron compound are removed from the hydrocarbon pyrolysis product and returned to the lower portion of the vessel. Coker 20 preferably is operated at superatmospheric pressure from about zero to as high as 200 pounds per square inch gauge, and preferably between about 30 and 100 pounds per square inch. Coke-laden particles of iron oxide and iron sulfide are removed from coker 20 by means of line 23 controlled by valve 24 and are sent thereby to reducer 25.
The hydrocarbon pyrolysis products, as a vapor phase, pass from separator 22 by means of line 26 through cooler 27 and subsequently via line 28 into coker bubble tower 29 wherein they are fractionated. Other forms of distillation column such as a packed tower may be used as well. The overhead product passes by means of line 30 into cooler 31 wherein a partial condensation of the lower boiling hydrocarbons is effected. The combined liquid and gas pass via line 32 into separator 33 wherefrom the liquid products are withdrawn via line 34. A portion of this passes by means of line 3S controlled by valve 36 into the upper portion of fractionator 29 as reflux while the remaining portion passes via line 37 controlled by valve 38 to further processing facilities or storage facilities not shown. This hydrocarbon stream comprises a coker gasoline which, depending upon the operation of coker bubble tower 29, may have an end point of from as low as about 150 F. to as high as 400 F. In this operation 23.6 barrels per day, or 2.65 tons per day of a 250 F. end point gasoline are produced.
The gas phase present in separator 33 is removed therefrom via line 39 controlled by valve 40 and is introduced into absorber 41 in which the removal of normally liquid hydrocarbon fractions from the gas is effected. To effect this removal, a gas oil fraction is removed from bubble tower 29 by means of line 42, passed through cooler 43 and introduced into absorber 41 by means of line 44 controlled by valve 45. This hydrocarbon fraction, a coker gas oil, passes downwardly through absorber 41 countercurrent to the upwardly rising gases and a dry gas consisting substantially of hydrogen, methane, ethylene, ethane, and the like, is removed by means of line 46 controlled by valve 47.
The rich absorption oil produced in absorber 41 is removed therefrom by means of line 48 a portion of which is returned via line 49 controlled by valve 50 to coker bubble tower 29 while the remaining portion passes by means of line 50a controlled by valve S1 to be hydrogenated as hereinafter described. The quantity of coker distillate thus produced for hydrogenation amounts to 21.2 barrels per day, or 3.24 tous per day.
Metal oxide reduction Returning now to the treatment of the coke-laden iron oxides and iron sulfides which are formed in coker 20, these solid particles are collected in one portion of Coker 20 from which they are removed by means of line 23 controlled by valve 24 at a rate of 31.4 tons per day and introduced into reducer 25. This solid material analyzes, in per cent by weight, as follows:
Constituent: Weight per cent Iron Sulfide 8.8 Higher iron oxides 66.4 Coke 22.0 Chloride 1.9 Sulfur e 0.9
This material passes into the reducer at about 900 F.
The operation of the reducer is such that an effective carbon or coke burn-ofi" from the solid particles upon .whichfthef coke was laid-down in, cokeraZt).` iseffected. The ,cokeis burned inthespresence of` an-.oxygen-con.- taining. gas such .as air. .to poduce .mainly carbon, m011- .oxide :This coke-.burnfofl isfcarried ,outat temperatures between about 1400 F. and 1800 F. or higher. nA suitable; temperature forthis .reaction .is .ahout- .1650". F. Simultaneouslyy with ythe -coke burn-off, theV coke; present ,onnthef-iron. oxide..partielesgelfects a substantially. completereduction of.v this iron oxide toan iron ,compound .ofa-loweroxidation statefcapable of reacting twith water to; liberatehydrogensuch :as particles of .ferrous oxide v(Feo) or particles of elemental-.iron in nely divided form; vToeifect this operation 1.9'5.MSCF/Hr.v (1,000 Standard cubic feet per hour) `ofabsorber-dry gasor other hydrocarbon .gas such as -natural gas, .which may be preheated to atemperature-of about' l200 F., lis-introduced-into reducer 25 via line-52 controlled by. valve'z53. At thesetemperatures, `afhydrocarbonfironu.oxide reaction occurs which gives rise to the formation ofz/carbon monoxide, hydrogen, water and elemental iron. T o efyfeet the coke burnoif, 3.81 MSCF/Hr. of air as .the oxygen-containing gas, which also may be preheated to a temperature of about 1200"F., is introducedxinto the lower portion of reducer-25 vialine '54 controlled by valve 55. By controlling the operation of reducer 25, the'contents of the vessel are maintained in such a condition. that .the solid,.particlesare.hindered from `settling and asuspensionof .the solid. .particles having leve1f56 is maintained` in the lowerpart ofthe vessel.
Above level;56 .is `collected a. producerfgas richglin carbon. `monoxide and hydrogenwhich .is yformed gduring the. iron,.oxide, reduction. Tol .produce highpurity iron from the. reducer, it is `preferable tomaintain a carbon monoxide, to carbondioxide ratio (volume) v.of vgreater than about; 1.0 in .the producer gas, such/asfbetween.about 2.5,v and 5.0. .A. ratio dabord-.3.0 yis, preferredto.` insure reduction1 .of the .oxides .to4 elemental Hiron. lFor` reduction ,to ferrous. oxide (FeO)`a. ratio offfromuabout 0.5 .to as high as about 3.0- may -be-used. This gas is. introduced into separatorg57 .inwhich tracesfof. suspended particles are,.re`moved and returned tothe-high density suspension .phase below level156l 1Frornthe=fupper portion .of separator. l57, .5.39. MSCF/Hrcof-a produeer e gas analyzing about 80% carbon monoxideisfremoved,aba
temperature of about l650 F. v ia line 58. This producer gas passes subsequently Vthrough heat exchange means .59 whereby it.is.`cooled .,-oonsiderably-.losingi its h eat, in -one modilication of this,.invention,;,in indirect ,heat exchange with .thehydrocarbon gas( and air. introduced, as previously described, ,into .reducer'25- ,The producer gas is` thus vcooledto a. temperature below `l-,0( ),0 F.y and is .passed byI .means of line60. intoseparatornl wherein- `remainingtraces, 'of suspended solid vparticles are. removed. Tghese particles. may. be recovered j yfrom thevproducer gas `ina high-.voltage electrical .precipitator or ina Specially .designedcentrifugaltype separator such asA a cyclone. `-Recovered. .particles maybereturned to (reducer 25 vvia 1ine162. The.v solids-.free.gproducer V gas `is removed, from. separatorl ,by means. ofline r63;.A andgsa portionof. this.'is..sent via line .64 eontrolled-byyalve 65 forV useas fuel, such `.asin furnace--18a in which the incoming heavyoil feed, recycle'coker -residuum, and hydrogenated residuum .are raised lto Ycoling temperatures prior to .their introductioninto colierZt). The remainder of the carbon monoxide. gases` pass-vialine 66 forffurther processing .in connection withthe .recovery of elemental. sulfury from .the sulfur dioxide bearing gases. prof duced during the conversion of iron sulfide to `iron oxide, as hereinafter more fully described. The reduced solids are removed-from reducer 25 via line 112 and a--portion may be passed through. line112a controlledbyvalvey 113a directly into..the coker .inwhich part-of the desulfurization may. be effected .at .ook-ing temperatures.
Meinl. .Sulde oxidation In oxidizer 67, 7;73 tons per day of solid material containing 91% iron sulfide, magnetically separated from the reducing regenerator eli'luent, as hereinafter described, are-introduced -and.,-converted to ironr oxides ('Fe304). Thisreaction is conducted `ata-temperature of .about 1200 F. although .temperatures-as low as about-l,000 F. to as high asabout 2,000 Fforihigher-.may .be-employed, `.if desired. The -iron sulfide is ,suspended in an air stream introduced.,bygmeansof line; `6.8 controlled by Valve I 69 `and thegsuspensionv together .with recirculated irontoxide is .passed-via aline. 70` ,th-rough Wasteheat rboiler 71 wherein.a.portien.of :the heabgeneratedduringo davt-io11-.of| `the. iron suld'e, is, dissipated .inconvertingnwater introducedvia line 831x controlled by valve 82 into. steam whichis removed-from .separator 83 via 4linelflqcontrolled by. yalveS. The suspension `isnthen ,passed Ifrom boiler-7f1 via.flinev 72.into oxidizerf-67. A. level-.731 is maintained: in .oxidizer;.67= -belowqwhich iron sulfide-and iron` oxide .particlesarevmaintained, in a condition of hindered. settlingy as. a relatively -h-igh .density suspension. The solid particles are removed from oxidizeru67yia l-inerf74 controlled1by.fvalve'75andqatportion thereof is returned via.1line'.76,.controlled by -valve .77 to'pbere- .combined .with Vthe. incoming` `iron. sulfide, and air; for recirculation through lwaste heatfboilert71. vThequantity offthiswrecycle stream'Y amounts to. about f 1;081.tons=.per day,.-although higher, or'lowerf recycle rates. may, be employed, in order; to maintain: f-the-,oxidizer temperatureat .the desired` value. The. remaining quantity of-oxidized material, .passes via line T7.8 `controlled; :by valve `"79nto auxiliary reduceitvufat :theY rate of 7.1.tons -per day and has approximately thea yfollowing composition:
Within auxiliary reducer S0 4this downwardly `owing solid mixture contacts a countercurrent streamof gas removed'from reducer25 at a rate oflz4' MSCF/Hr. by means of line 86 controlled by valve 87 and which contains carbon monoxide. This countercurrent contact ef- .fetsfa substantiallyAcompletereduetion-of :the FezOs to Pe3Q4,..and.simultaneously; the solids, are heated? to; approximately the. temperatureexisting kwithingthe reducer, .that v.-i s,-about 165.0921?. ,Tfhe EesOtfthus. produced, c0n tainingabout `8.0% iron ...sulfide and `substantially1.10.0 FegQs, isftpasnsedfrom auxiliaryfreducer byfmeanslof linegcontrolled. by-valye ,'89 into reducergl.' :The: -gas removed; .from auxiliary reducen 80. after contacting `.the oxidizediron .sulfide from Aoxidizer 167 `passes-viaeline 90 ontrolled.byyvalvefllqintooxidizerz,67.
- hin.,ex;i dizer 6.7:athe.i.ironqsuliide:is..oxidizedf.to `a ure-of ,iron1-oxides-..;with itheysimultanoous; production yofgases rich inf. sulfur dioxide. .Under-conditions ofthe presentoperation these-gases are removedgfrom oxidizer .67 gthrough separatory Q2 `by lmeans .of' which *st irspended.v particles of iron oxides are separatedmandreturned -to a point below level 73. The solid=free sulfur dioxidebearing gases are removedfrom separator 92 by means of line 93v controlled by valve94 and are introduced into separator'95 which preferably isof the high voltage type; bymeansV of which remainingtraces ofV very'ne solids are-precipitated'.v yThe solids'thus recovered may be disposed of or returned to the system by means of line 96. The sulfur dioxide bearing gases, freefrom .y suspended particles, ,pass fromseparator .95 by. means `of `lir 1e..9'7,.atp.ara-te` of 22,0, MSCF/ .and are combined with 14.3 MSCF/Hr. of producersglscontain-` ing .a high concentration ocarbonmonoxide owing through line .6.6.
Sulfur `proeiLlzction The gaseous mixture. thus formed' has a temperature of about 1100 F. andcontains carbon ,monoxide-and sulfur `dioxide underconditionsat which they readily react toproduce-elemen-tal sulfur according to thefollowing reaction:
rThis gaseous mixture vis-.cond-uctedby means of line 98 into waste-heat boiler 991'wherein the heat generated is employedltoconvert Watertosteam. =Water is introduced. byifmeans of line controlled by valveltlland steam formed is removed from separator 102 bymeans of-2line 103 controlled by Valve 104. The heat made available by this reaction is about 300,000 B..-t. u. per hour, a substantial portion of which is recoverable in the.` form of high pressure steam. Gases areremoved from boiler 99' at a temperature of about 1185o F. by means of line 105 and are introduced into heat exchange means 106 wherein the gases are preferably cooled to a temperament-below,about 250 Fplosing their heat in; this modifieation .at.- a -r,ate -of about 500,000 B.. t..-,u.
per hour in the generation of steam. Sulfur is hereby precipitated in solid form and liquid sulfur may be recovered, if desired, by maintaining the temperature above 250 F. such as for example, at least 300 F. This gas in introduced via line 107 into separator 108 whereln the sulfur is separated. Sulfur is thus produced at a rate of about 1.8 tons per day and is removed from separator 108 via line 109. The sulfur thus produced 1s of high purity. The solid sulfur is in a nely divided form suitable for a wide variety of uses, especially fruit tree dusting.
The reaction of carbon monoxide and sulfur dioxide does not go to completion so that the gases removed from separator 108 by means of line 110 are contaminated with unreacted quantities of sulfur dioxide and small quantities of hydrogen sulfide formed through the reaction of sulfur dioxide with water vapor. In order to recover these quantities of sulfur, the gas removed from separator 108 via line 110 controlled by valve 111 is employed at a rate of about 34.2 MSCF/Hr. to convey and simultaneously to cool the iron etiluent removed from reducer 2S at a rate of 26.2 tons per day by means of line 112 controlled by valve 113. These solids are removed from reducer 25 at a temperature of about 1650 F. and
have approximately the following Weight composition: Constituent: Weight per cent Iron 49.5 Iron oxide (FeO) 17. Iron oxide (Fe3O4) 9.9 Iron sulfide 21.3 Chloride 2.3
In doing this an etiicient contact of the residual sulfurbearing gases with iron is effected substantially completely converting the sulfur to nonvolatile metal compounds such as iron sulfide. The metal sulfur compounds are recirculated through the system for reprocessing and permit the discharge to the atmosphere of gases substantially uncontaminated with sulfur and a substantially complete sulfur recovery. The gaseous suspension thus formed passes by means of line 114 into separator 115 wherein the solids, comprising a mixture of iron oxide and iron sulfur compounds together with iron, are separated from the heated gases. The solids thus conveyed and cooled are removed from separator 115 at a rate of about 26.7 tons per day at a temperature of about 825 F. These solids have approximately the following composition:
Gases are removed from separator 115 at a temperature of 825 F. via line 116 having a substantially reduced sulfur content.
The solid material containing recovered iron sulfur compounds removed from separator 115 passes via line 117 and may be quenched by direct contact with about 80 tons per day of water introduced by means of line 118 controlled by valve 119. The temperature is thus reduced to about 150 F. and 190,000 B. t. u. per hour of heat are recovered. The slurry of solids in water pass via line 120 into primary magnetic separator 121 wherein a substantially complete separation of iron sullides is effected. The elemental iron and iron oxides thus recovered is removed from separator 121 via line 122 controlled by valve 123 at a rate of 25.1 tons per day. The stream has approximately the following composition:
This slurry of iron and water is combined With 212 barrels per day of coker distillate removed from the 8 lower outlet of absorber 41 and flowing through lines 48 and 50a controlled by valve 51. This material is subsequently passed by means of line 124 to the hydrogenation step of the process which will subsequently be described.
Also removed from magnetic separator 121 is a stream of the relatively nonmagnetic materials containing substantially all of the iron sulfide, and some iron oxide, the chlorides, and the like. This material is removed by means of line 125 controlled by valve 126 and is introduced into secondary magnetic separator 127 wherein a separation of the ash and chlorides is effected from the iron oxides and iron suldes. The ash and chlorides and other nonmagnetic materials are removed by means of line 128 controlled by valve 129 and are discarded. The iron sulfide concentrate is removed by means of line 130 controlled by valve 131 at a rate of about 10.2 tons -per day and has approximately the following composition: y
This material passes by means of line 132 and is combined with a large volume of gases removed from separator 11S via line 116 at a temperature of about 825 F. This gas is again employed to convey solid materials and simultaneously to remove last traces of sulfur compounds. Water is evaporated to form a completely gaseous suspension of iron sulde and a small quantity of iron oxide (FesOt) and the suspension is passed by means of line 133 into separator 134 at a temperature of about 425 F. Within separator 134, suspended particles of FeS and Fe3O4 are removed from the suspended gas. These are passed by means of line 135 controlled by valve 136 at a rate of 7.7 tons per day to be combined with air for introduction into oxidizer 67. The sulfur-free gases are discharged to the atmosphere by means of line 137 at a rate of about 34 MSCF/Hr. A substantially complete sulfur recovery as elemental sulfur may be effected in this manner.
H ydrogenaton Returning now to the actual hydrogenation step, the coker distillate owing through line 50 at 212 barrel per day rate is combined in line 124 with 25.1 tons per day of a slurry of iron and water formed as described above. The slurry passes via line 124 into mixer 138 to which additional water may be added by means of line 139 controlled by valve 140, if desired. With this additional water may be added water-soluble salts of various types which enhance the hydrogenation reaction or these hydrogenation accelerators may be added, if desired, directly to the hydrogenation reactor. Hydrogenation accelerators applicable in this respect are the water-soluble halides of metals such as calcium, magnesium, iron, manganese, and the like, as well as the halides of ammonium.
The slurry prepared in mixer 138 passes by means of line 144 into high pressure pump 142 by means of which the slurry is compressed to a pressure which approximates that required in the ultimate hydrogenation reaction. This slurry is passed under high pressure through line 143 at a rate of 59.6 tons per day controlled by valve 144 into heater 145. Material introduced into heater 145 has the following weight composition:
In other operations, the composition may be varied to obtain different degrees of hydrogenation. From 5% to 35% iron, or ferrous oxide, 2% to 25% water, and 30% to 90% oil may be employed, for example.
This material is removed from heater 145 by means of line 146 controlled by valve 147 and is introduced at a temperature between about 500 F. and 1200 F. into 9 hydro'g'eatien reactor-148i In fths particular operador-a temperature of about 750 F. was employed in the hydrogenation o'f-th'e cokerf' distillate.' Hydrogenation'reactor 148 is provided `withv'a'gitator149and` driving -mean's v-150 whereby"the` contents of the-'reactor are maintained 'in' a condition of -thorough agitation during'the entire reaction".
It yis` sometimes desirable; where heating of the combined hydrogenatio'n reactorfeed lis not feasible, to separately heat the oil containing the suspended iron in one stream and the water which may containfa 'dissolved hydrogen accelerator in"the-oth`er. In'this modification, the magnetic separation is effected' in the' absence of water. The water is ithen introduced at high `pressurevia ylinei119a throughla separatecoil-in heater ,145 at a rate controlled by valve 150cv directly into reactor .148. The temperature may be above'o'r `below that of 'the inlet oil stream and may in some instances be at pressure and-temperature conditions above the critical. Such an'operationpermits the complete iron-steam reaction yfor hydrogenproduction to `take placeunder'the conditions best suited for hydrogenation. A veryieffective utilization of the hydrogen thus formed is effected;
The pressure under whichl the hydrogenation reaction isaccomplished is above atmospheric ranging as high as 115,000 pounds per square inchVV (1,000 atmospheres). Lower pressures-may 'be employed 'such as less lthan about 10U-pounds per'square inch, although in the hydrogenation vofsuch material as Coker distillate'obtained from Santa Maria Valley crude petroleum; pressures in the range of from 3000 to' 9000 pounds per square inch are desirable.-
During-itsV passage through `hydrogenation reactor 148 the mixture of irony-water and cokerdistillatereacts for the conversion ofthe unsaturated 'hydrocarbon 4constituents of the coker distillate yto saturated or paraffinicfractions, the-destructive hydrogenation of the higher molecular weight and higher boiling-hydrocarbon constituents for the production ofl saturated hydrocarbons boiling in the lower temperatureranges, the destruction of nitrogen, oxygen and sulfur-containing hydrocarbon compounds with the formation of ammonia; water, and hydrogen sulfide, respectively, and substantially completely hydrogenated remnants of these` constituents, the conversion of the-iron andI FeO through reaction `with water to higher oxides 'of iron such as Fe304 with the simultaneous production of vhydrogen which'is employed substantially* as it is formed vin 'the aforementioned hydrogenation reactions, and the conversion of a portion ofthe iron or iron oxides to sulides of iron through reaction withy hydrogen sulfide or with the sulfur-'containinghydrocarbon compounds.
The heterogeneous mixture of solids and'liquids coni taining dissolved gases'fis removed from hydrogenation reactor 148 by means of line151 controlled byva1ve'\152. A' portion'of the hydrogenationfreactor'eiuent Eth'us removed may fberecycled through heater 145' via line 151:1 controlled by `valve 152a4 bycirculation purrip1-153a.v In thi'smanner the'entir'e system; heater andreactor', may operate under 'substantially :isothermal conditionsfsoy that hydrogen generated Vby reacting iron withwater vis'formed at' the hydrogenation temperature permitting a'v substantially complete utilization as formed. Sucha'mixing of a portion'of fthe hydrogenated effluent with the-feed lto the reactor permits quickheating and avoidsV thecondition encountered whereby vthehydrogen is generated attempe'ratures duringrheating which4 are not `sufli'ciently `high to effect the desired degree'of hydrogenation.
Theremaining portionof the reactor efuent is' intro; duced into the lcentral lower portion of hydrogenation effluent bubble tower 153'. Inthis'fractionating column, xthe hydrogenation reactor efue'nt is separatedZ into its'fcon'- stituent parts. Anoverhead vapor-passes by means of line 154 into" condenser 155 wherein 'a partial condensation'of vthe lower Iboiling constituents is effected; This cooled product passes' by means of line 156'into separator 157 fromwhich'the gases areremoved by means ofline 158 controlled by valve 159 which also maintains aback pressure on'the'column: The gasthus obtaineclrmay contain a certain amount of hydrogen 'asA well,` asthe normally gaseous hydrocarbon constituents. This gas'rnay be'employed `ase fuel the` processyor may 'be sent `to` storage-or further' processing'.facilitiesA notfshown.- The condensateis removed :from separator 157 via line' I160 controlled `by valve '161 anda-portion is-returned -tozthe upper part of `tlierbubbletower by meansy of line `1621as 10 ferrer; Whse their-,maintiens cpfea'ud rhrugniiiie its at a rat'eoff55barrelsiper day-control-ledfbyI vali/e164; This-liquid fraction 'ic'o'r'nprises'a'V vhyd'r'od'es'ulfuriz'ed Agasoline which is substantially frees-from nitrogen andsulfur contamination; The A'gasoline may` be blended5 in any `desirable proportion with -unsat'ura'ted hydrocarbon fractions obtained "from the'-coker "gasoline *product* produced from the lupper'portio'n ofcokz'e'r'bubble tower 290", previousiy-"d'escribedi l Theeondi'tions :of tem'p'erat'ureandpressuref'whiih 'are employed-4in Tthe-'hydr'ogenation 'ste'p of -theprocess Emay lb'e'"modified by l"theiincorporationoffcatalytic-'quantities lof such; hydrogenation and/or -de`sulfurization catalystsa's nickefand cobalt oxides-lorVA suldes. Molybdenum or -tungstenoXides--or sultides-may als'obe employed.' To en'- hance de sulfurization, catalysts `sc'has' coba'it molybdat'egco'balt chromafe,' and the 'corresponding-nickel compounds may-'beint'roducedwith the-mixtureofwater, oil, and iro'n-or'ferrous' oxide-intothe`hydrogenation reactor'. Thcobalt' and nickel-oxidesand sulfdes-are especially-applicable'since ithese" compounds 'are' readily regenerated under the'iexistin'gl conditions' of Y.operationv lin which fthe oxide'sf'of ironarereduced. BySemploying-catalytic quantities of these compounds in the' hydrogenation' reactor, considerable reductions A"iir temperature andV 'p'r'e'ssurere-` suit: Those J'pre'ssures and temperatures in thelowerpart off'the'i-ange's given' above permit good' conversionsthat is, temperatures between about 700 i12-.and 800 F. andpressu'r'es of less 'than about .'5000 pounds lIper squareinch;
Ammonia is produced' during-the destructivez'hydrogenati'on ofv nitrogen-containing hydrocarbons. Inv order to eftectanl efficient' recovery of this compound,the' reflux temperaturel of `bubble `tower '153 `-may `be'maintainedat about 210 F1 under atmospheric pressure-operation whereby 'a substantiallyy completefrecovery of `unrea'cted watercontainingdissolved ammonia may be effected by continuouslyfdrawing' of'this 'commodity from ktray 165 through `line-166 controlledby valve 167. A hydrodesulfurized"gasoil 'havingf a ,boiling zrange `of'ifrom about 200 F. to'-a'bout` 800 F. maybeuremoved,iifdesired, fromthemiddle portion of'colurnn'153 vialine 168'controlledby'va'lve 169. This commodity is produced at a rate of 157 barrels per day. i.
r-l."he"bottom"part of column 153 '.isumaintained at va temperature'cf between"700"' F. and 11000" F. and a small `quantity of hydrogenated residuumis *removedV via line 170. AAportionfof this is recycled 4by means of line *171fcontro1led by valve 17.2 to a point-somewhat above they inlet fof thematerial removed fromy hydrogenator 148. The-quantity of this'residuum amounts to'49 barreis-iper day.v This lmaterial has the following weight composition:I Constituent: Weight'pe'r cnt Hydrogenated residuuml FCS i,
100.0 The mteriar is freercuiatdby means offiiii ,1e-figa bubbleftower"1"53"I to' be" combined with' the' Santa Maria' Valley crude" oil :passing with the fcoker bubble@ tower residuum vialine"18"into` heater18` completing the According fto the jm'c'yJrdiication o f 4thejprocessy jof'this in'ient'ion, yas above described; an l eiientV econorr'iical arid-eas`ilyico'ritrolled process ffor the -substantially coinplete'l -con'version )ofy thigh" density oils' in'tofi desirable 'hydrocarbon. 'fractions of flower density "and lo'wr boiling rangerisprovided.L Furthermoreg'fthe products which are obtained ythrough application offthel processare substantially-'free from undesirable nitrogen, oxygen'and sulfur compound contamination and provide highly` desirable rawmaterials for the formulation l'of internal; combustion engine fuels suchl als ga'sygaso'line,v diesel fuel, andl the like;y and vmayalso 'provide suitable stocks for the prepartimiof'high' quality'. lubricating oils and .greasesL4 etc?,y these "conditions are notu to 'be' osidered limita ingI since y`a certain:latitude'foffvari f'oii7 is permissible" wherebygthel de'sirabl'e'fresults `may bebbtained.' It lis to "be" further understood' that although the 'high density foil" treated in the above description was a high density crude petroleum having an A. P. I. gravity of between 10.0 and 12.0, other high density oils may be similarly treated and the same desirable results effected.
The operation of the reducer may be varied such as by altering the temperature and the carbon monoxide concentration to form ferrous oxide, FeO, in preference to elemental iron. This then may be reacted with water to yield the hydrogen required in the hydrogenation step. The use of ferrous oxide instead of elemental iron has been found to be of advantage, since under some conditions of operation, such as in the higher temperature range, there is no tendency for the ferrous oxide to sinter or agglomerate or otherwise to form larger particles at the expense of the smaller particles and reduce the active surface of the material.
In another modification of the process of this invention, liuidized operations are also performed in the coking of the oil feed in the presence of coker residuum and hydrogenated residuum, in the oxidation of iron sulfide to iron oxide to form sulfur dioxide and in the reduction of iron oxide to iron in which latter step the coke laid down on the iron oxide during the coking operation is removed by combustion with the formation of a gas rich in carbon monoxide similar to the preferred process described above. Herein the oxidizing regenerator may produce sulfur dioxide or elemental sulfur depending on oxidizing conditions.
In this modification the high gravity oil such as crude oil, shale oil, tar sand oil, coal oil, residuums, and the like, is combined with a hydrogenated residuum containing suspended particles of iron sulfide and iron oxide. The stream is then combined with a stream of iron oxide (Fe3O4 predominantly) and is passed preferably through a fired heater where the temperature is raised to between about 700 F. and l200 F. to initiate a thermal pyrolysis. The heated material is then introduced into a fluidized coking vessel. In the coking vessel, thermal pyrolysis of the heated combined oil streams is effected in the presence of suspended particles of iron oxides and iron sulfides. A level is maintained within the coking vessel below which the heated particles of iron oxides and iron sulfides are maintained in a condition of hindered settling wherein the coke resulting from the thermal pyrolysis reaction is deposited on the suspended solid particles. Above this level accumulate the pyrolysis products comprising hydrocarbons in the vapor phase. These hydrocarbons pass through a separator present in the upper portion of the coking Vessel wherein small quantities of suspended particles are separated and returned to the r lower portion of the coking vessel below the level of solid particles. The solid-free pyrolysis product comprising hydrogen and saturated and unsaturated hydrocarbons having boiling points as high as about 800 F.
and higher are removed from the separator and introduced into a coker bubble tower where fractionation of the hydrocarbons thus produced is effected.
In the coker bubble tower and overhead gas product containing hydrogen, methane, saturated and unsaturated C2 and some C3 hydrocarbons are produced. Condensation of a portion of the vapor removed from the upper portion of the column forms a coker gasoline having a boiling range from about 70 F. to as high as about 400 F. The end point of this coker gasoline may be varied by varying the overhead product temperatures of the coker bubble tower. A coker gas oil may be removed from the coker bubble tower at a point intermediate between the pyrolysis product inlet and the overhead vapor outlet. This product contains saturated and unsaturated hydrocarbons boiling in the range of from about 300 F. to as high as about 800 F., the actual boiling range depending upon variable operating conditions of the column. From the bottom of the coker bubble tower, a coker residuum is removed which may be recirculated and combined with a feed stream and reintroduced into the coking vessel for reprocessing. This residuum may also be employed as a raw material for road-building hydrocarbons such as road oil, asphalt, and the like.
If desired, the coker gasoline and coker gas oil may be combined to form a coker distillate which is hydrogenated for the formation of desulfurized and saturated hydrocarbons suitable for internal combustion and engine fuels, lubricating oils and greases. If desired, these streams may also be treated individually by hydrogenation as will be subsequently described, or by other processes.
Returning now to the coking vessel, a stream is removed from below the level maintained in the coking vessel which comprises coke-laden particles of iron oxide (Fe3O4 predominantly), and iron sulfide. This material is suspended in a gas, if desired, or is otherwise directly introduced into a fluidized reducing regenerator.
The reducing regenerator effects the combustion of carbonaceous materials such as coke present on the iron oxide and iron sulde particles, and also effects a substantially complete reduction of the Fe3O4 to finely divided elemental iron or to lower iron oxides such as FeO. The temperature of operation at which the reducing regenerator effects these conversions may be between about l000 F. and 2000 F., a temperature of about 1650D F. being typical. An oxygen-containing gas such as air is introduced directly into the reducing regenerator in controlled quantities to effect coke combustion which favors the formation of carbon monoxide and liberates heat aiding the iron oxide reduction. Introduced at a separate point in the reducing regenerator is a gas containing hydrocarbon and/or carbon monoxide such as natural gas, producer gas, or mixtures and the like, which assists the reduction of oxides of iron to lower oxides or elemental iron. These gases, the oxygen-containing gas, and the producer gas or natural gas are preferably introduced below the level of suspended solids maintained in a fiuidized state in the reducing regenerator. It is also to be preferred that a portion of these suspended solids be continuously removed, passed through suitable heat exchange means, and reintroduced in a closed cycle to maintain temperature control of the reaction.
In the reducing regenerator conditions are controlled so that the gases produced during the reaction contain hydrogen and water vapor in a ratio of about 2.0 and carbon monoxide and carbon dioxide in a ratio of at least 3.0. Under a pressure of operation which may range from near atmospheric to a high as several hundred pounds per square inch and under the conditions of temperatures disclosed above the production of a gas containing the constituents recited in the ratios given insure a substantially complete conversion of coke and of the iron oxide introduced into the reducing regenerator to finely divided elemental iron. A stream consisting of iron and iron sulfide essentially, and also containing small quantities of iron oxide is continuously removed from the reducing regenerator and subjected to a magnetic separation wherein the iron and the other materials with high magnetic susceptibility are separated from the iron sulfide. The iron thus recovered is employed in the hydrogenation of the coker distillate.
The iron sulfide recovered from the magnetic separator is combined with air and continuously introduced into an oxidizing regenerator in which the oxidation of iron sulfide to iron oxide is conducted under conditions suitable for maintaining the solids in a state of hindered settling and at a temperature of from 1000 F. to as high as 2000 F. In the oxidizing regenerator a suspension of solids is maintained in which a level of liuidized soligds is present. In the upper portion of the oxidizing regenerator the gases produced in the oxidation reaction are passed through a centrifugal separator for the removal of suspended solid particles. Suspended solid-free gases are subsequently removed from the separator containing sul-fur dioxide or elemental sulfur depending upon the conditions of operation, Elemental sulfur in liquid or solid form may be produced in the system by operating with a minimum quantity of air required in the iron sulfide oxidation and by controlling the effluent gas temperature so that at least part of the iron sulfide is converted to iron oxide and sulfur. In this modification the iron oxide formed from the iron sulfide oxidation is continuously removed from the oxidizing regenerator, cooled, and combined with the hydrocarbon feed to be coked and is introduced therewith through the heater into the iiuidized coking vessel.
As indicated above, the stream of solids removed from the reducing regenerator is magnetically treated to recover a concentrate of elemental iron. This is mixed to form a slurry with at least part of the hydrocarbons obtained from the coker bubble tower and with water. The actual quantities of iron and water in relation to the amount of oil to be hydrogenated have been set forth above and are dependent upon the quantity of olefinic or comme .13 otherwise 'unsaturated:hydrocarbonswhichl are'. desirably converted to. paraiiinicorfsaturated compounds. Under the1conditions of-the` hydrogenation, iron'reacts'fwith Water withthe formationof iron oxide .and the liberation of hydrogen according to 'the following reactionn This reaction supplies-hydrogen required in the. hydrogenation reaction andis consumed substantially as it is formed. The quantity of iron and water is selected to .provide `sufficient hydrogen to1 effect the idesired degree of hydrogenation.
lt is desirable to assist the hydrogenation reaction and the hydrogen generation by the addition' tol the. slurry of halides of `ammonia or "various metals such .as iron, manganese, magnesium, calcium, and. the like, which function as accelerators.
The slurry, containing the .constituents above'described, is pumpedl through a .means for heating wherebyV temperatures from about500 F'. toiabout `1200.o `F-.or more are developedinthe system. The heatedoilis-Y introduced thereby into a hydrogenation reactor-at a pressure as high as about 15,000 poundssperrsquare inch. This'vessel is preferablycontinuously agitated to permit uniform suspension of thereactingsolids 'inf the liquid and to assist'temperature control. Water, heated and .under pressure, may be added separately fromthe oili'andiron, or the slurry maybe combined witha part of the yhot reactor eiiiuent and introduced intothe reactor.
In the hydrogenation reactor, sulfur-containing;hy drocarbon constituents are decomposed'presumably by destructive hydrogenationwiththe :formation of hydrogen suliideand the hydrocarbon remnant of the :sulfurcom pound. The hydrogen suliide ultimately reacts Witheither theiron or the iron oxides present forming iron sulfide in the system.. Nitrogen-containing hydrocarbon :compounds are similarly decomposed forming ammonia. The hydrogenator eiiuent containing the above indicated constituents is subsequently passed fromy the hydrogenation reactor to a means for effecting the separationof the various constituents. inthe preferred modification this means for separation may comprise a` distillation column from which gaseous hydrocarbons are removed together with hydrogenation hydrocarbon fractions, gas oil fractions and others. Provision is preferably made in .the distillation columnfor the removal of water containing dissolved ammonia which may be substantiallycompletely recovered by this means. Fromthe "lowest part of the distillation column .a hydrogenated residue of higher boiling hydrocarbons is-.removed which contains suspended `solids including iron oxide, iron sulde, and possibly some unreacted iron. This residuumi may be magnetically separatedfforthe recovery of solid particles, or in the preferred modication is. combined in its entirety with the heavy oil to be hydrogenated and is returned with that steam to the coking vessel for retreatment.
In accordance with this modification a high density oil -is'subjected to conditions of thermal pyrolysis and destructive hydrogenation wherebyv asubstantially complete conversion to .hydrocarbon fractions to more desirable boiling range is eifected. By-products, including ammonia, sulfur dioxide, sulfur, and possibly various suldes and oxides of iron may be produced. if desired. One outstanding feature of this process is the fact that a high pressure hydrogenation may be effected in the lcomplete .absence ofthe extensive gas compression facilities normally required in high pressure hydrogenation operations and also inthe absence of an expensive and often easily poisoned hydrogenation catalyst. Another advantage of this modification comprises the use of the magnetic separating means for the control of `iron sulde by separating this material continuously and converting it by oxidation to iron oxide. This eliminates recycling of iron sulfide uselessly through the process.
In an additional modification of the process according to this invention, a iiuidized Coker, a fluidized `oxidizing regenerator and a iiuidized reducing .regenerator are also employed. In this particular operation the heavyhydrocarbon stream to be treated is combined withl a hydrogenated residuum containing iron oxide and iron sulde and With a coker residuum and introduced viaa iired heater into 'the-coking vessel. The oxidizing regenerator is so positioned with respect toith'evcoker that iron oxide withdrawn from the oxidizing .regeneratoriwis combined with the .heated'hydrocarbon stream fromtthe heaterand '1?1 thezztwo :ares introduced: simultaneously into ..thef:cok"' g vessel. In this manner a substantial utilizationivof'the'` sensible'lheatV of .iron oxide 'from the oxidizingLrege'nerator is.'.utilized inicausing. .thermal pyrolysis. ofl the heavy oil beingcoked. Also in :this manner iront` oxideffromthe oxidizingi regenerator is passed. through the i cokingvessel and` alayer1of coke .is `depositedzuponV each particle.- The hydrocarbon stream from- 'theheater maybe vatautemperature of betweenaabout 700 F. and.. l200 F.v :and
' bubble tray typewhereinvarious hydrocarbon. fractions,
gaseous and liquid, are separated from one'. another. During coking, a certain .quantity'of'hydrogen suliide'is generally formedfrom. the decomposition of -sulfurfcontaining."hydrocarboniconstituents This materiallis removed-v together With the/hydrogen, C1 and C2 saturated andy unsaturated.hydrocarbons from the upper portion of the column. Infone modificationlof this invention, the gas thusproduce'd is subjectedito a-treatment adaptable-to removing the hydrogen. suld'e thus contained-such-as vby absorptionlin basically reacting adsorbentssuch as aqueous solutions of alkali metalf salts,A absorptionin solutions'of organic compounds'such as ethanola'mines, andthe like. The hydrogen sulfide-free hydrocarbon gases areintroduced into the reducing regenerator to-eifect the reduction of iron oxide to finely divided metallic iron as` 'sub sequently described.'
The normally lliquid `portion of the hydrocarbons `in the 'pyrolysis product are further fractionatedin'they coker bubble vtower to"producea coker distillate or coker gasolineeboiling from about F. to 400 F. anda coker gas oil boiling from about 350 F. to about 760 F. These individual vfractions may beproduced and sent'to storage, individuallyhydrogenated according to the process of this=invention,.or produced from the bubble tower'as a single coker distillate streamthe total quantity-ofwhich is' then hydrogenated. s
Fronrthe lowestportion of the coker bubble toweris removed a Coker residuum consisting ofthe higher boiling hydrocarbons whichmay be employed as fuel oil, road oil, in the preparationof asphaltic road-building material, and the like. This residuum inthe 'present invention is preferably combined with'the hydrogenated residuum and with the high density oil to be treated and the combined stream isintroduced into the coker for pyrolysis.
From the lower portion of the coking vessel is removed a stream of iinely divided solids comprising a mixture of iron oxide, iron sulde and coke. In this modiiication of the invention a minor portion such as from about 10% to 50% by weight of the stream is suspended in air orother oxygen-containing gas'and introduced at a temperature of about S50 F. into the oxidizing regenerator. Preferably aboutone-third of the stream Withdrawn from the Coker is thus treated.. Within the oxidizing regenerator, which may operate from .a temperatureof about 1000 F. to 2000 F. and preferably at about 1200" F. to l500 F. the coke is burned to carbon monoxide and carbon dioxider and the iron sulde is oxidized to form sulfur dioxide and the higher iron oxides. This reaction is conducted in the oxidizing regenerator in the presence of fluidized-solids whereby a level is maintained Within the Vessel. From below this level -and from that part occupied by the suspended solids is removed a continuous stream of solids consisting predominantly of the higher. iron oxides at a temperature of about l700 F. A portion of this-is combined with the higher iron oxide, iron sulfide and coke removed from the coking vessel and recirculated to the oxidizing regenerator to effect temperature control. The remaining quantity is introduced directly into thecoker Where a carbonaceousideposit of coke is laid down onthe particle yto permit ironoxide reduction and-aportionof which is converted to iron sulfide and treated as just above described.
The remaining portion of iron oxide, iron sulfide and coke removed from the coker comprises the major portion of the stream from about 50% to about 90% by weight is introduced into the reducing regenerator which may operate at a temperature of about 1400 F. and 1800 F. In transporting this fraction of solids removed from the coker to the reducing regenerator the solids may be suspended in a hydrocarbon gas or a producer gas and introduced as a fuidized system into the reducing regenerator. Within the reducing regenerator at a temperature of about l750 F. iron oxide is actively reduced to elemental iron by the action of hydrocarbon gas which may contain considerable quantities of methane and ethane and may, if desired, comprise desulfurized gas produced as the lightest product from the coker bubble tower as previously described. The operation of the reducing regenerator is preferably such that the gas produced therein contains carbon monoxide and carbon dioxide in a molar ratio of about 3.0 or more and hydrogen and water vapor in a ratio of preferably 2.0 or more. A level of fiuidized solids is maintained within the reducing regenerator from above which gases produced in the production reaction are withdrawn. From below this level is withdrawn a stream of solids comprising finely divided iron.
The gas removed from the upper portion of the reducing regenerator passes through a separator wherein it is free from suspended solids and the solid-free gas comprises a producer gas containing substantial quantities of carbon monoxide and hydrogen. This gas may be employed as fuel, as a source of hydrogen, or with a moderate amount of purification as a source of a mixture of carbon monoxide and hydrogen which may be employed as a synthesis in a catalytic carbon monoxide hydrogenation conversion for the production of synthetic organic chemicals and liquid fuels. Such catalytic conversions are typified by the l. G.Bergius process and the Fischer-Tropsch process.
A stream of finely divided iron containing some iron oxides is removed from the lower portion of the reducing regenerator and a part of this stream is recirculated with the material introduced into the reducing regenerator in order to maintain temperature control. The remaining portion is cooled such as by passing through a waste heat boiler and is subjected to a magnetic separation or other separatoin wherein a stream of substantially pure elemental iron particles is recovered. The nonmagnetic material may be returned to the process for retreatment since an appreciable quantity of this may comprise oxides and sulfides of iron of relatively lower magnetic susceptibility. The finely divided iron is introduced at a controlled rate into a mixer which is also added a controlled quantity of water and at least part of the coker distillate hydrocarbons obtained as products from the coker bubble tower. A slurry of this material is prepared in the mixer in which the ratio of iron to water is such that under conditions in the hydrogenation reaction iron will react with the water to produce a sufiicient quantity of hydrogen to hydrogenate to the desired extent the unsaturated olefinic and aromatic hydrocarbon constituents present in the coker distillate. This material is removed from the mixer by means of a high pressure pump and passed through a heater capable of quickly increasing the temperature of the slurry to between about 500 F. and 1200 F. depending upon the nature of the coker distillate and the type and severity of hydrogenation desired. Temperatures of the order of 700 F. to 850 F. are suitable for moderate hydrogenation of olefinic constituents while temperatures in the upper portion of the range such as from 850 F. to 1100 F. are well adapted to effect cracking in the presence of hydrogen in which case a thermal decomposition of the hydrocarbons in the coker distillate is effected accompanied by immediate hydrogenation of the hydrogen fragments formed.
The hydrogenation operation is preferably carried out at superatmospheric pressures which, for example, may be as high as 1000 atmospheres or 15,000 pounds per square inch. Suitable operating pressures for the hydrogenation reaction may run lower than this maximum such as between about 250 pounds per square inch and 7000 pounds per square inch. Under these conditions of pressure and temperature the hydrogenation not only saturates the unsaturated hydrocarbon constituents present, but also decomposes sulfur, nitrogen and oxygen derivatives of hydrocarbons with the formation of hydrogen suled, ammonia, and water, respectively. The hydrogen sulfide, at least in part, is found in the hydrogenation reactor efliuent as iron sulfide, While the ammonia formed accumulates in the unreacted water phase. The hydrogenation reactor is preferably provided with means for maintaining a continuous and eicient agitation of the contents of the vessel in order to insure uniform treatment and to prevent settling of the solids contained in the system.
The hydrogenation reactor effluent comprises a hydrogenated oil phase, unreacted water and solid particles comprising iron oxide, iron sulfide, and possibly some unreacted elemental iron. This entire material is introduced into a hydrogenated product bubble tower or other means of separation in which the hydrocarbon phase of the hydrogenator effluent is fractionated into portions having any desired boiling range. Depending upon the severity of the hydrogenation conditions, a variable quantity of gas containing saturated hydrocarbon gases may be produced. This gas is removed from the bubble tower as an overhead product, cooled, and the normally gaseous constituents are separated from the condensate. This condensate comprises a hydrodesulfurized gasoline, a portion of which is returned to the bubble tower as reflux while the rcmainder is produced from the column as a gasoline product. Also removed from the column is an aqueous phase containing ammonium hydroxide. A gas oil product may be also produced which may have a boiling range from about 400 F. to 800 F. The higher boiling hydrocarbon constituents are produced as a hydrogenated residuum from the lower part of the bubble tower and carry with it iron oxide and iron sulfide formed from the elemental iron during the hydrogenation reaction. This residuum is preferably treated to recover the iron compounds and may be combined with the heavy oil as feed stock to the process and returned therewith to the coking vessel.
This modification of the process, according to this invention permits a substantially complete conversion of low value high density oils to desirable hydrocarbon fractions uncontaminated by sulfur having lower boiling ranges and suitable for internal combustion engine fuels or as feed stock in the preparation of high quality lubricating oils and lubricating greases. The usual hydrogen compression facilities and the expensive sensitive catalyst together with some hydrogenation processes are hereby eliminated.
In the foregoing modifications of the process of this invention it has been found desirable, particularly in those cases when heavy or viscous hydrogenated residuums are formed which carry suspended solid particles, to convey a diluent oil into the hydrogenator bubble tower to assist in conveying this residuum. Recycling the coker bubble residuum as the hydrogenated residuum diluent has been found effective. Generally, the quantity of hydrogenated residuum is not large and not sufficient to carry the amount of solids present,
Another modification of the process of this invention exists in which a substantially complete vaporization of the hydrogenated effluent is effected to permit quick separation of the solid particles from the product.
A high density oil such as low A. P. I, gravity crude petroleum is combined with a coker bubble tower residue and with a hydrogenated residuum containing a small quantity of iron oxide particles and the mixture is heated to a temperature between about 700 F. and l200 F. and introduced into the coking reactor. Higher iron oxide such as FesO4 and FezOa produced from iron sulfide in the oxidizing regenerator is also introduced into the coking reactor in which the deposit of coke is laid down on the particles. Lower molecular weight unsaturated hydrocarbon fractions are simultaneously formed. The hydrocarbons thus produced are fractionated in a coker bubble tower with the production of gas, coker gasoline, and coker gas oil. The coker distillate is employed as feed stock to the hydrogenation unit and includes the gasoline, gas oil, and other fractions.
The coke-laden iron oxide passes from the coking vessel to the reducing regenerator into which air and part of the gas produced from the coker bubble tower are introduced. The reducing regenerator is a vessel in which a fluidized suspension of solids is maintained with the existence of a level of solids below which carbon oxidation and carbon reduction reactions are effected. A stream of iron particles substantially free of carbon and containing iron sulfide, ash and sodium chloride in minor amounts, is removed. The gas produced from the upper portion of the reducing regenerator contains a high concentration of carbon monoxide and also contains hydrogen and comprises a suitable producer gas which may be used as fuel or in the conversion of hydrogen sulfide or sulfur dioxide to elemental sulfur in a suitable reactor.
This stream of solid particles removed from the reducing regenerator is divided into two fractions, the major proportion of which is combined with the proper quantities of coker distillate and with water for introduction into the hydrogenation step of the process. The minor fraction is subjected to the action of the magnetic separator by means of which the ash and sodium chloride contents are separated from the iron compounds. The ash and salt-free matter obtained in the magnetic separator is combined with the major portion referred to previously and employed in the hydrogenation reaction.
A slurry is prepared containing coker distillate, water, and iron in the proper proportions so that the reaction of iron with water will produce a quantity of hydrogen sufficient to effect the desired degree of coker distillate hydrogenation. This slurry is picked up by a high pressure multistage pump and is passed together with additional water, if desired, at a controlled rate through a heater capable of raising the temperature of this mixture to between about 500 F. and about l200 F. For the hydrogenation of a coker distillate prepared from a low A. P. l. gravity crude petroleum such as that obtained from the Santa Maria Valley of California, a hydrogenation temperature of about 700 F. to 800 F. is desirable and a pressure of about 5000 to 7000 pounds per square inch although pressures as high as about 1000 atmospheres or 15,000 pounds per square inch may be used.
The heated mixture at superatmospheric pressure is passed from the heater into a hydrogenation reactor which preferably is provided with means for maintaining the liquid contents thoroughly agitated and the solid particles while suspended in the fluid. It is highly desirable to maintain a completely liquid phase hydrogenation. Within the hydrogenation vessel under conditions of temperature and pressure given above, water readily reacts with metallic iron with the evolution of hydrogen and the formation of iron oxide. The hydrogen reacts with the coker distillate to be hydrogenated before molecular hydrogen (Z-hydrogen atoms per molecule) is formed. The freshly formed hydrogen is known as atomic or nascent hydrogen. By consuming the hydrogen immediately and while it is in its atomic state, a highly efficient degree of coker distillate hydrogenation is effected. It is also possible in the hydrogenation reactor under temperatures above 800 F. to effect a destructive hydrogenation in which the boiling range of the hydrogenated product is lower than that of the coker distillate being hydrogenated and the hydrocarbon produced from the reactor may be readily vaporized.
A desulfurization reaction also occurs simultaneously with the hydrogenation whereby sulfur-containing hydrocarbon molecules are decomposed and the fragments hydrogenated with the formation of hydrogen sulfide and of hydrocarbons. At least a part of the hydrogen sulde thus formed reacts with the iron or the iron oxide to form iron sulfide which is removed with the hydrogenated hydrocarbons from the reactor. Oxygen and nitrogen derivatives of hydrocarbons are also decomposed with the formation of water and ammonia, respectively. The water thus formed may react with additional quantities of iron to form hydrogen while the ammonia dissolves in any excess water and may be recovered as an aqueous phase from the hydrogenated material.
The hydrogenated hydrocarbon stream passing from the hydrogenation reactor is suddenly depressured from the superatmospheric operating pressure through one or a plurality of expansion valves to a pressure at or near atmospheric pressure such as from about l to l00 pounds per square inch absolute. The material is subsequently passed through a coil in a heater and the combination of the expansion and the heating effects a substantially complete vaporization of the hydrogenated effiuent. The gaseous hydrocarbon stream thus produced carries with it suspended particles of iron which may be unreacted and with the iron oxide and iron sulfide. This vapor stream passes into a suitable separator which may comprise a cylindrical tower with a centrifugal separator disposed in the upper portion thereof. By means of the separator the suspended` solid matter is removed and passes over a series of baffles down through the tower countercurrent to a stripping gas such as steam which serves to rerixave remaining traces of liquids or gases from the so s.
The solids are removed from the lower part of the vessel, suspended in a stream of air and conveyed as a suspension into the oxidizing regenerator referred to above in which the oxidation of iron sulfide is effected in a fiuidized system. The combustion of iron sulfide to form iron oxide results in gases containing considerable quantities of sulfur dioxide. This gas may be chemically reduced by reaction with carbon dioxide by combining oxidizing regenerator effluent with the proper proportion of reducing regenerator effluent or producer gas so that the following reaction occurs:
A substantial liberation of heat results which may be employed in a waste heater boiler to depleted high steam and simultaneously cooling the sulfur-bearing gases to below about 250 F. to permit centrifugal or electrical precipitation of the solid sulfur particles.
Returning now to the hydrogenated efiiuent separator, a vapor stream comprising vapor phase hydrocarbon and water is removed from the separator and introduced into the hydrogenator bubble tower whereby a fractionation of the hydrogenated effluent is effected. Gases are produced from the upper portion of the tower as well as a hydrogenated and desulfurized gasoline gas oil and other hydrocarbon fractions of different boiling range. From one tray in the tower an aqueous phase containing ammonium hydroxide may be produced. The hydrogenated hydrocarbon fractions thus produced comprise suitable raw materials for the preparation of high grade internal combustion engine fuels, solids, lubricating oil and lubricating greases, etc. A small amount of residual material remains in the system and may be produced as a bottoms product from the hydrogenator bubble tower and is returned and combined with the feed stock to the system whereby it is recoked.
The fundamental advantage of this modification lies in the hydrogenation step wherein a substantially complete separation of the unreacted iron if any and the solid iron compounds is effected by expanding the hydrogenator efuent from its superatmospheric pressure to substantially completely vaporize the stream followed by a centrifugal separation of the solid products suspended in the gas. This modification of the operation is readily carried out particularly when the lower boiling products are desirable such as the gasoliues and gas oils.
In the modifications of the process of this invention as glven above the operating pressures in all cases except that of the hydrogenation are at or near atmospheric pressure. It is preferable to operate a uidized system at pressures somewhat in excess of that of the atmosphere to ald in effecting proper control of the operation. Consequently the preferred pressure range for the operat1on of. the fiuidized coker, the reducing regenerator and the oxidized regenerator is from about zero pounds to about pounds per square inch gauge, a pressure of about 30 pounds per square inch gauge being well suited to this particular operation. The operation of the coker bubble tower and the hydrogenated effluent bubble tower 1n which hydrogenation distillations are effected are preferably operated at pressures in the same approximate pressure range.
As previously stated, the hydrogenation operation may be carried out at superatmospheric pressures as high as about i000 atmospheres or aboutl 15,000 pounds per square mch. Operating pressures for the hydrogenation step m the range of from about 3000 to 10,000 pounds per square inch are well suited to effecting the desired results and operating pressures of from about 4000 to about 7500 pounds per square inch have been found suitable.
In each modification, hydrogen generation arises from the reaction of Water with a metal above hydrogen in the electromotive series, that is with a metal capable of replacing hydrogen from water forming a metal oxide reducible by carbon. In the modifications described above iron has been set forth as the metal. There are, however, other metals which are capable of effecting this reaction to the desired extent. Among these metals are zinc, cobalt, nickel, manganese, and the like. This includes the metals of atomic Nos. 25 through 30 of Il9 Mendeleefs'periodic' table of the' elements with thef exceptionof copper.-
In themoditication of thel process of this invention described above, a substantially complete desulfuriz'ation of a hydrocarbon fractidriiiiay' beeffected by hydrogenation; This'i's ataomplished in the lziydrogenationy reactor under the temperature and pressure and other conditions described' above. Another modification exists by means of which desulfurizationnfi'ay be at least partially effected inthe colcing reactor' inwhich atl leastl aI part of the elemental iron produced' from theA reducing regenerator is combined'. with the hydrocarbon feedstream passing into the' coker'. 'lhef presenceof.- elemental iron at coking temperatures sufficient to thermal-ly decompose sulfurcontaining hydrocarbon compounds permits the hydrogen sulfide thus liberated to readily convert part of the iron to iron sulfide. The immediate effect; of incorporating elemental1 iron with the hydrocarbon stream tothe coker is that ofreducii'ig thc'sultur content of the hydrocarbon fractions produced from the Coker bubble tower, and reducing the hydrogen contamination in' the hydrogenation step of the; combination process.
In the modificrationsv of the process of this invention described above, exclusive reference has' been made to the treating of heavy' gravity crude petroleums by' means of which these hydrocarbons are coked in4 the presence of iron oxide, the' coke-laden iron oxide is suitably treated to reduce the iron oxide to iron; and the iron is reacted with Water in the presence of at least' part' of the hydrocarbon' products obtained during the coking reaction to form hy'dr'ogenatedand desulfu'rized liquid and hydrocarbon fractions. It should not be understood that the process of this invention is exclusively applicable to the treating of petroleum hydrocarbons since similar desirable results may be brought about in employing the heavy gravity oils 'and tars obtained from coal distillation as feedstock. These tars and oils. are essentially aromatic in nature'co'n't'airi'ing high molecular weight condensed ring structures and include such materials as benzene, toluene, xylene, naphthalene, anthracene, phenanthr'ene, lirysene, picene, and other polynucleur aromatic as lwell as heter'ocyelic compounds'. Various condensedl struc-'tures such as ind'eneV and tiuorene, as well as the higher rnolecu'lar weight aromatic acids known as phenols andl the higher molecular weight aromatic bases of the pyridine type'l also occur. By employing such cal tar frac-'tions as feed stock in the process` of this invention; desirabl'y lower boiling hydrocarbon fractions may beobtaii'ied which may contain a variable quantity of residual aromatic hydrocarbons and may also containpv-rfible quantities of cyclic saturated hydrocarbons of the riaphthene-typeas Well* as parafiinic hydrocarbons depending upon the severityr of the coking and of the-hydrogeiiatio step. Highly desirable hydrocarbon fractions rn'y be readily obtained from this type of feedy stock.v
The process, according tothis invention may be further applied to the hydrogenation of normally solid carbonaceoiis materials of which examples are bituminous coal, lignite,- peat, brown coal, and the like. The process of this inventionis modified to the extent that the carbonaceous material or coal' to be treated is finely pulverized in a suitable grinding mill' and mixed with a tar recycle to form a paste-ora liquid suspension of coal solids in the oil. This tar recycle 'may be one obtained from the coker wherein the paste is coked with the liberation of further quantities of aromatic type coal tars or it may bea residual oil froml the hydrogenation effluent bubble tower which desirabl'yl is reprocessed. During the operationV of this modification of the process iron oxide produced from the oxidiiing regenerator is combined with the paste and introduced into the coker or it may be introduced into the Coker directly. The hydrocarbon oils liberated from the coal during coking are subsequently mixed with iron, for example, and water and hydrogenatedundr high pressure as previously described. Such materials as oil sand, tar sand, oilsoaked diatofnite may be treated in a manner similar to that described above for handling carbonaceous solids such as coal.
The process of the present invention described' in detail above permits the ready'c'tnivrsit'in` of' carbonaceous materials whether they are-solids' or liquids to desirable hydrocarbon fractions substantially free of' contaminating elements by a combined" operation of coking in the presence ofa metal. oxide depositing' a carbonaceous solid on the metal oxide, andlhydrogenating the` thermal pyrolysis product obtained during the coking operation by reacting the metalf with water under high pressure and temperature to produceA hydrogen. The process eliminates the disadvantages inherent in previous hydrogenation processes, namely, the requirement' for expensive and sensitive hydrogenation catalysts', the requirement for extensive hydrogen compression facilities, and others.
A particular embodiment of the present invention has been described in considerable detail by way of illustration. It should be understood that various other modifications and adaptationsl thereof may be made by those skilled in this particular art without departing from the spirit and scope of this invention as set forth' in the appended claims.
l. An apparatus for the refining of hydrocarbons which comprises a hydrocarbon pyrolysis vessel, an inlet conduit for hydrocarbon opening into the lower part thereof, an outlet conduit for pyrolysis product opening from the upper part thereof, a reducing vessel, a conduit for solids communicating said pyrolysis vessel with said reducing vessel, an inlet conduit for gas opening into the lower part thereof, an outlet for gas opening from the upper part thereof, an outlet for solids opening from the bottom thereof, a heating means, an inlet conduit thereto communicating with said outlet conduit for pyrolysis product opening from said pyrolysis vessel and with said outlet for solids opening from said reducing vessel, an elongated reactor vessel, a movable agitator means extending longitudinally throughout the entire length thereof, motive means for actuating said agitator means, a conduit communicating the outlet of said heating means with an inlet at one end of said reactor vessel, outlet means opening from the other end thereof, a pumping means, a first recycle conduit directly communicating said other end of lsaid reactor vessel through said pumping means with said heating means, hydrocarbon separator means communicating with said outlet means from said reactor vessel, an outlet for hydrocarbon product opening therefrom, and a second recycle conduit for hydrocarbon and solids communicating said separator means ultimately with said pyrolysis vessel.
2. An apparatus for the refining of hydrocarbons which comprises in combination a hydrocarbon coking vessel, a reducing vessel and an elongated reactor vessel, a first heating means, an inlet conduit for hydrocarbon opening thereinto, a conduit opening from said first heating means into the lower part of said coking vessel, an outlet conduit for coker distillate opening from the upper part of said Coking vessel, a conduit for solids communieating the lower part of said coking vessel with said reducing vessel, an inlet conduit for gas opening into the lower part thereof, an outlet conduit for gas from the upper part thereof, an outlet for solids opening from the bottom thereof, a second heating means, an. inlet conduit thereto communicating with said outlet conduit opening from the upper part of said coking vessel and with said o utlet for solids opening from the lower part of said reducing vessel, a conduit opening from the outlet of said second heating means and into the lower end of said reactor vessel, a movable agitator means extendinglongitudinally throughout thel entire length thereof motive means for actuating said agitator, a pumping means, a first recycle conduit communicating directly from said upper end of said reactor through said pumping means with the inlet conduit into said second heating means, a hydrocarbon distillation column, a conduit communicating the upper end of said reactor vesselwith said distillation column, means for removing hydrocarbon product therefrom, and a second recycle conduit communicating the lower end of said column with the inlet conduit to said first heating means.
3. apparatus f or the refining of hydrocarbons which comprises 1n combination a coking vessel, a reducing vessel, an oxidizing vessel and an elongated reactor vessel, an inlct conduit for hydrocarbon opening into the lower part of said coking vessel, anoutlet for coked hydrocarbons opening from the upper part thereof, a conduit for solids opening from the lower part of said coking vessel into said reducing vessel, an inlet conduit for gas opening into the lower part of` said reducing vessel, an outlet for gas opening from the upper part thereof, a solids fractionation means, a conduit for solids opening from the lower part of said reducing vessel into sald fractionation means, a rst conduit for solids therefrom opening into the lower part of said oxidizing vessel, means for introducing gas into the lower part thereof, an outlet conduit for gas from the upper part thereof, a conduit for solids opening from the lower part of said oxidizlng vessel into said reducing vessel, a second conduit for solids opening from said solids fractionation means, a solids and liquid mixing means communicating wlth said second conduit for solids and with said outlet from the upper part of said coking vessel, an inlet condult for water into said mixing means, a heating means, a conduit opening therento from said mixing means, a conduit opening therefrom into the bottom of said elongated reactor vessel, a movable agitator means extending longitudinally entirely through-said reactor vessel, motive means for actuating said agitator, a pumping means, a first recycle conduit communicating directly from the top of said reactor vessel ythrough said pumping means to the inlet to said heating means, a hydrocarbon fractionation means connected in hydrocarbonreceiving relation with the top of said reactor vessel, at least one outlet conduit from said fractionation means, and a second recycle conduit communicating said fractionation means with said coking vessel.
4. An apparatus for the refining of hydrocarbons which comprises in combniation a coking vessel, a reducing vessel, an oxidizing vessel, a vertical elongated reactor vessel, and a second reactor vessel, a lirst heating means, an inlet conduit thereto for hydrocarbon feed, an outlet conduit therefrom opening into the lower part of said colting vessel, an outlet for coked hydrocarbons opening from the upper part thereof, a conduit for solids opening from the lower part of said coking vessel into said reducing vessel, an inlet conduit for gas opening into the lower part of said reducing vessel, an outlet for gas opening from the upper part thereof into said second reactor vessel, a solids fractionation means, a conduit for soilds opening from the lower part of said reducing vessel into said fractionation means, a first conduit for solids opening from the lower part of said resad oxidizing vessel, means for introducing gas into the lower part thereof, an outlet conduit for gas from the upper part thereof opening into said second reactor vessel, a conduit for solids opening from the lower part of said oxidizing vessel into said reducing vessel, a cooling means, an outlet conduit from said second reactor vesse opening into said cooling means, a separator, a conduit opening thereinto from said cooling means, an outlet for gas from said separator, a second outlet for sulfur therefrom, a second conduit for solids opening from said solids fractionation means, a solids and liquid mixing means communicating with said second conduit for solids and with said outlet from the upper part of said coking vessel, an inlet conduit for water into said mixing means, a heating means, a conduit opening thereinto from said mixing means, a conduit opening therefrom into the bottom of said elongated reactor vessel, a movable agitator means extending longitudinally entirely through said reactor vessel, motive means for actuating said agltator, a pumping means, a first recycle conduit communieating directly from the top of said reactor vessel through said pumping means to the inlet to said heating means, a hydrocarbon fractionation means connected in hydrocarbon-receiving relation with the top of said reactor vessel, at least one outlet conduit from said fractionation means, and a second recycle conduit communicating said fractionation means with said coking vessel.
5. An apparatus according to claim 4 wherein said solids fractionation means comprises a continuous magnetic separator.
6. An apparatus according to claim 4 in combination with a solids-gas contacting means, an inlet conduit for solids opening into said contacting means at one end thereof from the lower portion of said reducing vessel, an inlet conduit for gas opening into one end of said contacting means from the outlet of said second reactor vessel, an outlet conduit for solids from the opposite end of said contacting means from said inlet conduit for solids opening thereinto and which communicates with the solids inlet to said oxidizing vessel, and an outlet for gases at the opposite end of said contacting means from said inlet conduit for gas opening thereinto.
7. An apparatus according to claim 4 wherein said hydrocarbon fractionation means comprises in combination a ash vaporizer means and a vapor-solids separator and a conduit opening therebetween, an outlet conduit for vapor from said separator, and an outlet conduit from the lower part thereof communicating with said second recycle conduit.
8. An apparatus according to claim 4 in combination with an auxiliary solids-gas contacting vessel, an inlet conduit for gas opening into the lower part thereof from the upper part of said reducing vessel, an inlet conduit for solids opening from the lower part of said yoxidizing vessel into the upper portion of said auxiliary vessel, an outlet conduit for gas opening from the upper part thereof, and an outlet conduit for solids opening from the lower part thereof and into said reducing vessel.
9. An apparatus according to claim 4 wherein said hydrocarbon fractionation means comprises a distillation column, at least one outlet conduit therefrom for distillates, and an outlet conduit from the bottom thereof which communicates with said second recycle conduit.
References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,266,161 Campbell et al Dec. 16, 1941 2,311,978 Conn Feb. 23, 1943 2,325,611 Keranen Aug. 3, 1943 2,379,027 Monro June 26, 1945 2,434,567 Jahnig et al. Jan. 13, 1948 2,483,512 Voorhies, Jr., et al. Oct. 4, 1949 2,540,706 Beck et al. Feb. 6, 1951