US2527575A

US2527575A - Method for handling fuels

Info

Publication number: US2527575A
Application number: US632767A
Authority: US
Inventors: Bruno E Roetheli
Original assignee: Standard Oil Development Co
Current assignee: Standard Oil Development Co
Priority date: 1945-12-04
Filing date: 1945-12-04
Publication date: 1950-10-31
Anticipated expiration: 1967-10-31

Description

2 Sheets-Sheet 1 Snverztor Gbbo rn q unnu 0001.00 u a Bruno E'. Poetkezz' c0300 quunnu Oct. 31, 1950 Filed Dec. 4, 1945 .i m oe nmrws Bruno. E. Roetheli; Cranford, N. J., assignor to fl Standard: Oil Development Company; acorpo-v a ration ofDelaware v *Application'Decennber 4, 19 i5;'Seria l N o. 632,7 1

The present invention relates to improvements in the art of treating hydrocarbons and more particularly lt'relates to-a method of'coking'hea-vy residual hydrocarbon oils, such as topped'o'r re duced crude rnineral'oils, toproduce liquidhydrocarbon oils of'lower boiling'rangei, some normally gaseous hydrocarbon products, coke an'dvaluable fuel gases comprising carbon 'monoxide and by drogenr f j A great deal of experimentationhas been di'-' rected toward developing continuou'sprocesses-for coking 'heavy'h'ydrocarbon ens." Asis well known in the art, most of the coking operations atpresf ent applied are of the intermittent type; In these" operations the oil is heated 'to' coking 'ternper'atures, subjected-to coking conditions in a heat insulated drain toyield; considerable quantitiesfof hard, adherent coke which *c'lin'g's ten'aciouslyio' the-walls andmustbe rem'oved at intervals of two or three days. EThis decoking procedure which prevents continuous 'oper'ation is time-consum ng and expensive; i Numerous" attempts have been" made "to'produ'ce the coke in such'a forni ascould 1 GClalmsa um-s51 ou's'and integrated process.

12 drocarbon oils substantially completely'into more fiielfg'a'ses-"by a continuousintegratedcoking proof be 'continuou'sly removed frorn' 'the drum' without substantial dep'osit therein so as to-arrive at fully continuous operation} Forinstance; a process: has been suggested which involves 'dischargingthe oil preheated to' coking: temperature into a drum containing rpowdered or granular coke *inthe forni 017a :semi suspended fluid';: turbu1entm'ass,"con tlnuously withdrawing the added coke together with the formed coke'; passing {the total cokeiinto another zone where 5lt'-' iS driedj' har'dened and' highly heated while undergoing partial i combus tion, and returning the hot c'oketo .the'fcoki'ng zone to supply at least a 'portlon of'the hea't required' for coking'i e This procedure' which "applies the so-called fluid sollds'technique lprovidesan operativefcontinuous coking process=afiording goodyields-ofmore valuable liquid and fgaseous "hydrocarb'on'i products However, the process is not "entirely satisfactory for various reasons; In the coklng of low-grade residues'from-crudes or"pitch"stills; etci, the per'." centage of coke-formedmay range as high-as 40 to 45%' on the charge; This amount of' colnbus tibles is-far' in excess of that required to maintain the heatb'alance of the"cokingrea'ctionby partial combustion of the heat-carrying ciroulating' coke';

This situation presents the problern ofdise'arding solid coke'from theoperationx Handling ofsollds in general is cumbersome and entails transporta tlon' problems} briqnetting or other additional workforthe'di'spo'sal or-furtherus'e'of'the coke's The broad object of the present invention is to valuable" liquid and 'gaSeous hydrocarbons and ess q erated by thejfluid 'solids technique-' a Other and further objects and advantages *of th'pre'sentinvention m be a'ppareray-rm' the following: description and -claims readw'ith ef= erence to the accompanying drawing? 1 aa thaveg'found thatthese objects maybe accomplishedlargelyby:new =adaptationsgand improvee i: rnents-ofthe principlesdisclosed inlmyco pending application se'rial-No.' 609:,662', filed A'ugust 8 1 945,;which==is arcontinuation-in-part of my 430-: pendingzapplication Serial No. 487,187; :fil'edxMay 15; 1943; andzwhich deals :with a continuous prociess foriiconverting solid. 'carbonaceous' materials containing: distillable constituents into valuable vol'atilefnels bypassingafluidizedstreamof finelyr-vdivided' starting material through suitable conversion zones; such as carbonizatio'n and/or gasification; zones, and using heat of combustion 'to supply .the :heat required inithe conversionrzo'nes.

The present application'is a continuation in par't ofv-said co-pending application Serial No." 609,662,"

filed Au'gust 8y1945',and adaptsthe process of said cm'riending application- 'to :them c'oking'x: of 'heavy l mineralioil residues by means'of variouszmodifications and improvementsiwhich willlappeai more a clearlyihereinafter; '5 w in In accordance with-one embodiment of v my present -inventionpheavy" hydrocarbon' 'oil resi duesiarecharge'd; preferably continuously; 'to' a fluidized solids reactiohvessel containing a fluid-' ized bed' of *finely divided solids such" as coke) preheated-sufiicientlytosupply the heat req'uired for coking. Volatile coking products and highly reactive coke are separately and preferably continuously withdrawn and the coke is subjected in a second reaction zone to a gasification reaction producing valuable fuel gases and proceeding at a temperature substantially higher than that of the coking zone. Fuel gases are recovered from said second zone and solid gasification residue is preferably continuously returned at or at about the gasification temperature to the coking zone in amounts sufiicient to supply at least a substantial part of the heat required for coking.

Steam, inert gas, water gas, natural gas, flue gases or the like may be used to fluidize the solids in the coking zone which may be maintained at temperatures varying from 800 to about 1200 F. If desired, a portion of the heat required in the coking zone may be supplied by partial combustion within the coking zone. An oxidizing gas, such as air or oxygen or mixtures thereof, may replace part or all of the fiuidizing gas for this purpose.

The gasification zone may be operated to produce water gas, producer gas, mixtures of carbon monoxide and hydrogen suitable for the catalytic synthesis of liquid hydrocarbons or fuel gases rich in carbon monoxide or the like at temperatures falling within the approximate range of 1200 to 2500 F. For the production of water gas or synthesis gas, steam and sufiicient oxygen to support the combustion needed for the heat balance requirements in the gasification and coking zones are supplied preferably simultaneously. When the generation of producer gas or another fuel gas rich in carbon monoxide is desired, mixtures of steam and air or air or oxygen alone or suitable mixtures thereof are supplied to the gasification zone in the proper proportions to generate the heat required to raise the burned coke to the temperature necessary for heat balance in the coking zone and to support the desired gasification reaction.

In a more specific modification of this embodiment of my invention just enough air is supplied to the gasification zone to raise the temperature therein to 1600-l800 F., or higher. Under these conditions the gas leaving the gasification zone contains up to about -35% of carbon monoxide and may, after dust separation and desulfurization, be utilized as fuel gas for heatin purposes or as fuel for gas turbines or blowing engines.

Independent of the type of fuel gas produced,

the gasification zone is preferably so operated that an amount of coke, roughly corresponding to that newly formed in the coking zone, is gasified so that the amount of circulating solids may be maintained at a substantially constant level by merely bleeding off a small amount of ashy or other non-combustible solid constituents which may in turn be used to preheat the oxidizing gas and/or steam required for gasification.

Another embodiment of my invention involves the use of a separate zone for conducting the combustion to supply the heat required for oilcoking and coke-gasification. In accordance with this embodiment of my invention, coke from the oil-coking and/or a fuel gas generating zone is passed, preferably continuously, to a third fluidized solids zone wherein the coke is subjected to combustion with an oxidizing gas, such as air and/or oxygen, at temperatures ranging from 1600 to 2500 F. if desired in the presence of steam or other auxiliary gas which may also aid in the iiuidization of the coke. Solid combustion residue and/or other noncombustible solid is returned, preferably continuously, to both the oil-coking and fuel gas generating zones to supply at least a portion of the heat required therein. If desired, additional heat may be generated within the coking and/or gasification zone by supplying air and/or oxygen directly to said latter zones.

A.more specific modification of this latter embodiment of my invention provides for adjusting the amount of oxidizing gas in the com bustion zone so as to produce a gas of relatively high carbon dioxide content at temperatures ranging from 1700 to 2500 F. and returning this gas, preferably continuously, together with steam to the gasification zone operated at about l600-2400 F. This results in the reduction of carbon dioxide to carbon monoxide by the highly heated coke present in the gas ification zone and the conversion of steam to carbon monoxide and hydrogen. The composition of the fuel gas produced in the gasification-reduction zone may be varied by varying the proportions of steam and coke, by charging additional coke or coal or carbureting oil or by similar means. An amount of solid residue approximating the ash content of the residual oil charge may be purged from the system and used for heat exchange purposes, as indicated above. When oxygen alone is used as the oxidizing gas in the combustion zone, the combustion gas may be charged to the reducinggasification zone directly. When air is used, it may be desirable to concentrate carbon dioxide by scrubbing to eliminate part or all of the nitrogen and to return the concentrated carbon dioxide to the reducing-gasification zone after suitable preheating.

From the foregoing, it will be readily understood that my invention provides a continuous oil-coking process which, in addition to more valuable hydrocarbon coking products, affords full utilization of the carbonaceous matter charged in the form of highly valuable fuel gases while confining the disposal of non-process solids to relatively minor quantities.

Having set forth the general nature and ob- J'ects, the invention will be best understood from the more detailed description hereinafter, in which reference will be made to the accompanying drawing wherein Fig. 1 is a semi-diagrammatic view in sectional elevation of an apparatus for carrying out the present process in two separate zones, and

Fig. 2 is a semi-diagrammatic view in sectional elevation of an apparatus for carrying out the present process in three separate zones.

Referring now to Fig. 1, numeral I denotes the coking chamber or coker which is in the form of a cylindrical vessel fitted with a conical base 2 separated from the cylindrical section by a distributing grid 4. To start the process, the cylindrical section of coker I is filled to about one-third to one-half of its height with a finelydivided solid material supplied by any suitable means, for instance by a screw conveyor 6, as shown in the drawing. The finely-divided solid material should have a particle size of the order of below 50 mesh, or even less than mesh, although even small lumps up to A" or /2" size may be used. Coke, preferably oil coke, of the proper size is normally used although any noncombustible solid material, such as sand, ash, catalyst, etc., may take the place of coke in this stage of the process. A fiuidizing gas, such as steam, inert gas, water gas, natural gas, flue gases or the like preheated in heater 8 to about 3 than: ,n m ir mr ss ns m t h wm-e. vsolid s m ca r. ldue isfw thd ewairamse man rove: sa l b werdl hml sh e; s male? 1mm; 91 th ms eue s tn m f ab at t g n n o v v r k H the temp t e b h s fl gnrzane wellgdefin'edfupper leyg s isimultjainebuslyg h throu n .3 9k f p e rab1y a .a.- point fluidized mas of solids is? pr h ate y the! l abo e we landl meun s w l -flank? s p gas '.the'fi" desired jc'okin tem erature. of the heat required by the coking reactionin coker 8O01200 F.',"jor slightly v@Glals.volumes m I, A considerably smaller portion of solidgasiflof 100110: 1006; cu; ft, per hour; and ca; regor cation -residue, approximately corresponding to coker space arenormall'y' adequate for thisfpu'r the ash and otherwise introduced non-, combustible pose, althoughthesevalues may vary according solids content of the charge, is passed through line to the naturejandsize'of. thesolidscirculated. 44 to steam preheater 46 which may have acon When'the fluidized mass h sreaclied asu'itable: struction similar to that ofvessels l-: and 2.2; coking temperature, a heavy hydrocarbon resi- Steam or a mixture of steam and oxidizing-gas due, such as reduced crude which aylorfmayenters preheater 46 through line 41, the conical not be preheated;isfintroducedithrough line I2 bottomsection and distributing grid lltobe into coker 'l',,preferably.oat a .pointabovegridL preheated to the; desired temperaturebydirect The oil is quickly distributed jthrough out the heat-exchange with the non-combustible gasificawhighly-heated fluidized mass of solids and subtion residue forming a fluidizedmass withalevel ject' to the coking reaction. It .may'beldes irable 50 in vpreheater 46. Preheated steam A'orsteame to add an oxidizing gas; such as air and/or oxidizing gas mixture is passed through lines 6|; y to he; flu d n ga to upply addi and 28 to generator 22. Solid residue is withdrawn tional heat by partial' combustion particularly- 2;; downwardly frompreheater'IG-thmughyline 52 during the startingupperiod," H H o w I and may be-passed either through line 53 to dis- Volatile'coking' products, such as gas oil, 89-509 posalqmeans 54,0r through line 56 -.to line '9 to line and gaseous] hydrocarbons together with preheat the fiuidizing gas for coker l bythe refluidizing.gasarewithdrawriouerhead h'om cg'llrer. mainingsensible heat of theinonecombustible I and passedthroug'hgas-solids separator l'i and 3 solid' residue. g I I I line N 1111,5113! conventional sy tem I iot the re- 1 When the temperature in generator 22 covery ofthesehydrocarbons (not shown). t ficiently hightomakeavailablerthe heat required o d'fiuidiz d' coke is withdrawn downwardly in the coker land the steampreheater 46;:the from a'jpoint' above grid} thrqughlineli to dis a processwill beself-supporting-with-respect.to. persing chamber l8, neared; the flow of the heat balance, the total heat requiredubeingsupcokethroug'h'line I6 may be facilitated by thei plied by theexothermic. combustion reactionein addition of small; amounts of; iluidizing gas generator 22.; Fromthis time -on;;f luidizingagas through mesgm Indispersing chamber 18 the; heater land oxidizing gaslheaterpil may belbyev coke'is converted into asuspension of lesser denv passed throughlines -IBand;IlrespectivelyriThe sity by the addition pfagas zpreferably an-oxidiz 4}! process may b v c p t y balanced a d :v ing gass h as airor-Qxygen to' whichsteam fully-con nu us- Q- nt OHingthe gasiflcae may be added; and whichris supplied through line n a co st g eac ons in eneratorwlla I9 "The suspensionvf orrnedjs' passed thrqugh that-approximatelythe same amountot cokeis; line ztl junderIthe pseudov hydrostaticpressure\or nv ed into a e s ts ss rme in the flfluidized coke column in line 1st and enters, 4: k ..fluidi d coke being o tinu u y-c m 1 ri a iue as sener onill througha: etsdthmwh he tsystemas a hea a m er nd: conicalbase; Hand-distributing grid tohform" res ue b ng: on u y .fedl opo era above grid 'u a dense, fluidized; turbulent 'mass ThQfi Q iWxQI- e m sii om n a o similar to that in coker l; and having; a well-de,-.- l l qer l, d p d qs ext nt on the ten--- fined upper level 25. An oxidizing gas such: as? 50 e u ea y r c r-n we ne at 4 1 3 291,

r y en, a d/ r am; :Which during the coki" L n t ai e tia r h -b 1 s ue starting period maybepartiallyror completely rel-i; z k d 11 s coke! 'lf flf fl l fg ,n placedby fiue;gas-,and preheated in theater -21 ene a i z n '1 90 1.1 2 2. 9;

to temperaturesnf thetorder of :1600-;-2500 r1,-

h bpor ot of o z n s,sun l tvari are -suppliedthrough line'28,ac0nical' base 2: and A in accordance t he m to pr h a m,-

grid 14' rto generatoriizl in proportions; and o e rhut will n el 1 ab9u 10- Q-.35 Pi amounts; togetherwithgas suppliedthrough line. i t T Q o v a qn t 9 4 It- QIC -kH l9, adapted. to convert :asubstantial portion "or Q d en a t. f theh ii9 the coke into a; fuel gas, comprising mixtures of carbon monoxide and" hydrogen, and to su y;- sufllcient heatby combustion of coke to support the endothermic gasi'fication eg t m q tent oi -the gas generated is, of no significanee-ias or nst nc w env p qd r e sv r r r de: i ed. th pro ort n 0 st m I in rodu d w h-i e i le r a b on yl eet re u r dtto fluidizing or other. physical considerations. 1 It? Fuel gas ls'w'ithdrawnovrhead from generator higher at 1'v hydrogen are;required,,;steaml l n fi femij firis de s e ts!!! must .be ,added, as for instance in preparing; which a b ,aent liu lprsele tt q t v .9 water gas having a HzZCO lratioyof' 2:1 yfortuse rator and [whichmeturns iseparated solidfj'nnes" through line '33 to gener v M as feed gas for hydrocarbon synthesis when as Fuel g s-Su much-as 1,5 -2.0--cu. .ft. -(0;07-0-.10;pounds), 01,;

mm m s l e iee ses thie e effl te m. e t or '='+co r e it 11.1 fi e d Pmheater. wh r rm rive 7 n rs o h mand; o di i g-casein ofl some of its heat to the, educed crude feed stead ofrb eing supplied simultaneously d to,gen

81 1 n lthrbi sh li 5 nd Pas te: may i d edbelied 1 petl 5j through line 12 to colrer .I, If desired, part or all sulting in a make andiblows operation of gen o! the reduced crude feed mayIbYsP SSPIE QY: t 2 whenever ea esp o aitmzen;,q er= a through line 39. 'The fuelgas leaving pretent, such as'hydrocarbon-synthesis gas, are'desired oxygen is used as the oxidizing gas. The B. t. u. content of the fuel gas produced may be increased by the addition of a carbureting oil admitted through line 68 to generator 22. The entire system or either one of the reaction zones may be operated at slightly reduced, atmospheric or somewhat elevated pressures, ranging preferably from 25-125 lbs. per sq. in. gauge.

In the embodiment of my invention illustrated in Fig. 2 the heat required in the coking and gasification zones described in connection with Fig. 1 may be generated in a separate combustion zone and the carbon dioxide content of the combustion gases converted to additional amounts of fuel gas. Referring now to Fig. 2, the process is started up in a manner similar to that outlined in connection with Fig. 1. That is to say, coker 20! is charged with a limited amount of finely-divided, if desired non-combustible, solids through screw feeder 206 and a fluidized solids bed is formed in 20! by means of a fluidizing gas preheated in 208 and supplied through line 209 to the conical base 202 below grid 204 in coker 201. Oil residue, such as reduced crude, is fed through line M2 and coked by the heat of the fluidized solids bed. Volatile coking products are taken overhead through separator 2 l3 and line 214 and coke is withdrawn downwardly through line 2 i 6 to dispersing chamber 2i. where it is dispersed in combustion gases rich in carbon dioxide and steam recovered from the system, as will appear more clearly hereinafter. During the starting period until there is sufllcient combustion gas available an auxiliary fluidizing gas from any convenient source preheated in heater 221 may be supplied through line 2i6a to dispersing chamber 2l8.

The coke dispersion formed in H8 is passed through line 220 to the conical base 223 below distributing grid 224 of gas generator 222 wherein it forms a dense, turbulent, fluidized mass having a level 225. Temperatures within the range of 1600-2400 F. and relative proportions of carbon dioxide, steam and coke in generator 222 are so controlled as to reduce the carbon dioxide to carbon monoxide and to convert the steam and a substantial portion of the coke into carbon monoxide and hydrogen. Fuel gases are taken overhead through gas-solids separator 232 and line 234 and passed to storage or further processing through reduced crude preheater 236 which may receive the fresh reduced crude feed from pump 231 through line 238 or which may be bypassed lry the reduced crude through line 239. The reduced crude feed wholly or partly preheated reaches coker 20] through line 2i2.

A major portion of the hot fluidized solid gasification residue is withdrawn downwardly from generator-reducer 222 at a point above grid 224 and passed to dispersing chamber 2 through line 242. An oxidizinggas, such as air and/or oxygen, which during the starting period may be preheated in heater 221 on line 226, is supplied from gas feed line 241 through preheater 246 where it is in heat exchange with a minor portion of solid gasification residue or otherwise introduced non-combustible solid, as outlined in connection with preheater 46 of Fig. 1, and from there through line 228 to dispersing chamber 24 l. The coke dispersion which now has a temperature of between 1600 and 2500" F. is passed under the pseudo-hydrostatic pressure of the fluidized solids column in 242, through line 243 into the conical bas 266 el d 2'il of th cylin r cal combustion chamber or burner 262 wherein it forms a dense, fluidized mass of solids having an upper level 264.

A minor proportion of fluidized solid gasification residue or otherwise introduced non-combustible solid, roughly corresponding to the noncombustible solids content of the charge, is withdrawn from generator-reducer 222 through line 244 and passed in heat exchange with oxidizing gas through preheater 246, as outlined before. Solid non-combustible residue is removed from the system via line 263 and disposal means 254. The solid may be recycled to the preheater as desired.

In burner 262 the coke is subjected to combustion at temperatures falling within the range 01' 1700-2500 F. and under conditions favoring the formation of high proportion of carbon dioxide. For instance, temperatures of 1900 F. at a ratio of cu. ft. of air per pound of carbon content of all fluidized solids entering burner 262 may be advantageously employed.

Hot combustion gases rich in carbon dioxide are withdrawn overhead from burner 262 through gas-solids separator 266 from which separated solids are returned to burner 262 through line 265. The hot combustion gas substantially free of solids passes through line 268 to waste heat boiler 21l in which superheated steam is produced from water supplied through 269; steam is withdrawn through line 210 and mixed with the combustion gases in line 2l9 leading to dispersing chamber 2I8 via compressor 212. If desired, inert gases, such as nitrogen, may be removed from combustion gases in a carbon dioxide concentration system 214 arranged in by-pass line 215, and reheated in heater 216 prior to their admixture with steam in line 2 I 9.

A major portion of the mixture of fluidized solid combustion residue and otherwise introduced non-combustible solid is withdrawn at the burner temperature from burner 262 at a point above grid 26! and passed through line 218 to generator-reducer 222, preferably at a point above grid 224 and in amounts sufficient to supply the heat required by the gasification-reduction reaction in chamber 222. A minor portion of the solid fluidized combustion residue is withdrawn from burner 262 in a similar manner through line 280 and passed to coker 20l in amounts suilicient to supply the heat required by the coking reaction.

When the temperature in burner 262 is willciently high to make available the heat required in coker 2M and generator-reduce 222 through recirculated hot solid, the process will be selfsupporting with respect to heat balance, the total heat required being supplied by the exothermic combustion reaction in burner 262. At the same time the operation of heaters 206 and 221 may be discontinued and the gases by-passed through lines 2"] and 228, respectively. The gasification of coke in 222 and the combustion of coke in 262 are preferably so controlled that the amount of coke converted into gas corresponds roughly to that formed in coter 20 I. Thus, the process may be balanced and made fully continuous by continuously feeding heavy oil residue to coker 2M, continuously circulating hot solid composed largely of coke as heat carrier through the system and continuously withdrawing volatile products and small amounts of ashy or other noncombusti le solid constituents from the system. In this manner, the carbonaceous constituents of the charging stock are practically completelv converted into valuable volatile fuels with only minor quantities of non-combustible solid residues to be disposed of.

The absolute and relative amounts of solids circulated to and from burner 262 depend within fairly wide limits on the temperature difference between burner 262 and the other conversionzones, the reaction desired in generator reducer' 222 and the characteristics of the original charging stock. In general; operative conditionsfall considerations apply to. the proportions of 'reacting gases supplied to burner 262 and.generator-,

reducer 222. However, gas ratios. oif,0.2 cu.ft'. to

0.4 cu. ft. o f'oxygenfed to burner 262. and 0,5 cu.v

ft. to 1.0 cu. ft. of carbondioxide plussteam (measured at 60 Hand 1 atm. abs. pressure, whence 2 lbs. of steam:2l cu. ft.) fed to generator-reducer 222 per cu. ft. of CO-l-Hz formed will in general be operative. Preferred ratios are 025 cu. ft. of oxygen (e. g., inair) and 0.60 cu.-

ft. of carbon dioxideplus steam- It is pointed out that this embodiment ofmy invention permits of manyQmodificationsv Forv example, an oxidizing gas may bejifed to coker. 20I and/or generator-reducer. 222 continuously.

or periodically. to-supply additional heat by combus'tion within said zones or to modify the composition of the volatile products. The fuel gas prduced in generator-reducer 222 may be enriched in heating value by injecting 'a carbureting oil, such as a gas oil, through line "258. Hot solid fluidized gasification residue'lfrom line 242 may be returned through line.282 and dispersing chamber 284 to the fiuidizing gas line209 of coker 20| in order to supplyadditionalheat to the fluidizin-g gas and the coker. On the other hand, part .or all of the coke withdrawn ffrom coker 20l through line 2l6 may bepassedthrough line 286 to adispersing chamber 288, andtpicked up by oxidizing gas coming from; line 228 through line 290, and then'passed asa' dispersion through line 292 directly to burner-262. If .desiredgoy in case the ash constituents of the reduced crude charged should be insuflicient to supply sufllcient heat to preheater 246, suitable amounts of extraneous inert solids, such as sand, ash and the like, may be fed to coker 20I and/or burner 262, for instance suspended in the gases supplied to these zones, and circulated through the system with the coke as additional heat carrier. The process may be operated at slightly reduced, atmospheric or slightly elevated pressures, prefererably ranging from to 125 lbs. per sq. in. Also, it will be understood that generator 222 may be operated to produce merely carbon monoxide and hydrogen from steam and coke by omitting the carbon dioxide feed from burner 262. Through any or all of these modifications the process become extremely flexible and may be easily adapted to all types of charging stock and I volatile fuels desired.

action zones is smooth and proceeds without difflculty. The upward gas velocity should be of the order of 0.5-3 ft. per second where the solid. is, say, -200 mesh, and progressively higher. with larger sizes, say 10-20 ft. per second want lumps /2 inch. Thesevelocities are .suflicientl to prevent the settling of the solid. into compact masses and the reactions occur, very. rapidly when carried out while the solid is. his fluidized condition. More over, temperature control ex-"- tremely accurate. The minimum velocityot the.

gas required for maintaining a, fluidized condition varies somewhat with gthe.;nature an'dsize.

of the solid particles, and the particular ifluidizlng I gas but in general the variation is not-wideand the minimum amount is oftheorder of- 0.0l-0.10 cu.'ft. per lb.-; it mayconsist of gas,associated with thesolid as withdrawn from a zone o1. great er gas concentration, without the necessity for adding, other fiuidizir1g .gas. When 'fluidizin with such a small amount of gas, a very dense.

suspension, or stream results andthe effect =j0f addingv additional gas to the fluidized streamis the ,reduction' of the. density of the: suspension. Advantage is taken :of this property of the fluidized stream in order to efiecttherlowof thema terial fromzone to zone; 'Jlhus, in- Fig. ,1. the stream is caused to flowdownthe pipe .16 and up the pipe 20 by the addition; of .gas at the point l8.v The density ofthe .fiuidizedstream in-,-the

pipe l6 ismuch greater than in the pipe 20 and a pressure difierentialisthus generated,.which isequal to the product of theheight of the column in pipe li multiplied by-the densitytherein, minus the product height [of v the column20 multiplied by the density of r the stream flowing. therein The equipment should be. carefull designed throughout so v that the pressure'Qdiffer; ential is sufiicient to overcome the loss due, to friction. Small amounts ofgas may. beadded to pipes and chambers at various point ssofasto. maintain the fiuidizationg. This islparticularly important, wherefa fluidized stream is flowing downw.ardly.l ;-tlirough. a pipe wherein the ratio of,increaseinabsolute pressure i p fj the rder Oriana-restatemorer l l My. inventon will be furtherillustrate d by the following specific example which'g is not be construed as limiting the scope of my invention in any respect whatever.

Example Referring to Fig. 2, a charge consisting of about 100 lbs. of reduced crude is fed in continuous fashion to vessel 20l containing fluidized non-combustible solids at a temperature of approximately 900 F. The oil is coked to produce approximately 45% by weight of gas oil, 16% gasoline and 10% gas. The solid coke is present in the form of a finely-dispersed suspension. During the same time interval, to lbs. of coke or mixtures of coke and non-combustible solids are introduced at a temperature of about 2200 F. Approximately lbs. of solid material withdrawn from the bottom of vessel 20! through standpipe 216 is fluidized by means of air or oxygen-enriched air.

The mixture of air and solid is injected into the combustion chamber 262 in which enough of the combustible in the solid is burned to produce a temperature of 2200 F., approximately 700 cu. ft. of air being required for the purpose of producing the desired temperature level. About 100 lbs. of solid material (combustion residue) are drawn off from combustion chamber I" and returned to the coking vessel ill. Approximately 30 lbs. are charged to the gaslflcation vessel 222 in which a substantial portion of the residual carbonaceous material is converted to a gas rich in carbon monoxide when blown with air or oxygen at a temperature of 1810 F. or higher. When operating the gasiflcation chamber 222 with a superficial gas velocity of about 0.8 it. per second, a producer gas containing 34% CO was manufactured when using air as the oxidizing gas.

Many modifications of my invention will be apparent to those skilled in the art without departing from the spirit of my invention.

I claim:

1. In the method of coking heavy residual hydrocarbon oils wherein subdivided product coke is circulated in a fluidized system comprising a combustion zone and a coking zone and heated substantially above coking temperature while circulating through said system, the improvement which comprises intimately contacting an oil residue of the character of reduced crude at coking temperatures substantially above 800 F. and up to about 1200 F. with a dense fluidized bed of finely dividedsolid materials substantially free of distillable constituents and comprising non-combustibles to coke said oils, recovering volatile coking products from said coking zone, withdrawing fluidized coke from said coking zone, passing at least a portion of the coke so withdrawn directly to a separate gasification zone, reacting said coke with steam in said gasification zone in the form of a dense fluidized mass of solids at a temperature higher than said coking temperatures to produce a fuel gas, recovering said fuel gas separately from said volatile products, passing ungasifled coke from said gasiflcation zone to a separate combustion zone, subjecting said ungasified coke in said combustion zone to combustion in the form of a dense fluidized mass of solids to produce a combustion gas and solid residue heated to a temperature higher than said gasiflcation temperature, withdrawing said combustion gas separately from said fuel gas and said volatile products, controlling said gasification and combustion so as to convert to gas an amount of coke corresponding approximately to the amount of coke formed in said coking zone, passing solids at about the temperature of said combustion from said combustion zone to said gasiflcation zone in amounts sumcient to supply at least a portion of the heat required in said gasiflcation zone, and returning solids heated in said system to a temperature higher than said coking temperature to said coking zone in amounts sufllcient to supply at least a portion of the heat required in said coking zone.

2. The method of claim 1 in which at least a portion of said solids returned to said coking zone is withdrawn from said combustion zone.

3. The method of claim 1 in which at least a portion of said solids returned to said coking zone is withdrawn from said gasification zone.

4. The method of claim 1 in which carbon dioxide contained in said combustion gases is supplied to said gasification zone and reduced to carbon monoxide by the coke present in said gasiflcation zone.

5. The method as claimed in claim 1 in which extraneous solids are added to said fluidized solids passed from zone to zone.

6. The method as claimed in claim 1 in which an amount of fluidized non-combustible solids approximately corresponding to the amount of non-combustibles charged to the system is withdrawn from the system.

BRUNO E. ROETHELI.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,899,887 Thiele Feb. 28, 1933 1,984,380 Odell Dec. 18, 1934 2,400,075 Claussen May 14, 1946 2,436,160 Blanding Feb. 17, 1948 2,436,938 Soharmann et a1. Mar. 2, 1948 2,445,328 Keith July 20, 1948 OTHER REFERENCES Haslam et al.: Fuels and Their Combustion," pages 546-547.

Claims

1. IN THE METHOD OF COKING HEAVY RESIDUAL HYDROCARBON OILS WHEREIN SUBDIVIDED PRODUCT COKE IS CIRCULATED IN A FLUIDIZED SYTEM COMPRISING A COMBUSTION ZONE AND A COKING ZONE AND HEATED SUBSTANTIALLY ABOVE COKING TEMPERATURE WHILE CIRCULATING THROUGH SAID SYSTEM, THE IMPROVEMENT WHICH COMPRISES INTIMATELY CONTACTING AN OIL RESIDUE OF THE CHARACTER OF REDUCED CRUDE AT COKING TEMPERATURES SUBSTANTIALLY ABOVE 800*F. AND UP TO ABOUT 1200*F. WITH A DENSE FLUIDIZED BED OF FINELY DIVIDED SOLID MATERIALS SUBSTANTIALLY FREE OF DISTILLABLE CONSTITUENTS AND COMPRISING NON-COMBUSTIBLES TO COKE SAID OILS, RECOVERING VOLATILE COKING PRODUCTS FROM SAID COKING ZONE, WITHDRAWING FLUIDIZED COKE FROM SAID COKING ZONE, PASSING AT LEAST A PORTION OF THE COKE SO WITHDRAWN DIRECTLY TO A SEPARATE GASIFICATION ZONE, REACTING SAID COKE WITH STEAM IN SAID GASIFICATION ZONE IN THE FORM OF A DENSE FLUIDIZED MASS OF SOLIDS AT A TEMPERATURE HIGHER THAN SAID COKING TEMPERATURES TO PRODUCE A FUEL GAS, RECOVERING SAID FUEL GAS SEPARATELY FROM SAID VOLATILE PRODUCTS, PASSING UNGASIFIED COKE FROM SAID GASIFICATION ZONE TO A SEPARATE COMBUSTION ZONE, SUBJECTING SAID UNGASIFIED COKE IN SAID COMBUSTION ZONE TO COMBUSTION IN THE FORM OF A DENSE FLUIDIZED MASS OF SOLIDS TO PRODUCE A COMBUSTION GAS AND SOLID RESIDUE HEATED TO A TEMPERATURE HIGHER THAN SAID GASIFICATION TEMPERATURE, WITHDRAWING SAID COMBUSTION GAS SEPARATELY FROM SAID FUEL GAS AND SAID VOLATILE PRODUCTS, CONTROLLING SAID GASIFICATION AND COMBUSTION SO AS TO CONVERT TO GAS AN AMOUNT OF COKE CORRESPONDING APPROXIMATELY TO THE AMOUNT OF COKE FORMED IN SAID COKING ZONE, PASSING SOLIDS AT ABOUT THE TEMPERATURE OF SAID COMBUSTION FROM SAID COMBUSTION ZONE TO SAID GASIFICATION ZONE IN AMOUNTS SUFFICIENT TO SUPPLY AT LEAST A PROTION OF THE HEAT REQUIRED IN SAID GASIFICATION ZONE, AND RETURNING SOLIDS HEATED IN SAID SYSTEM TO A TEMPERATURE HIGHER THAN SAID COKING TEMPERATURE TO SAID COKING ZONE IN AMOUNTS SUFFICIENT TO SUPPLY AT LEAST A PORTION OF THE HEAT REQUIRED IN SAID COKING ZONE.