US2639263A - Method for distilling solid hydrocarbonaceous material - Google Patents

Description

F. W. LEFFER May 19, 1953- 2,639,263 l METHOD FOR DISTILLING SOLID HYDROCARBONACEOUS MATERIAL Filed 00T.. 5. 1948 @A a www w 5 ,j C? 4 Il f 2 6 6 f A .-.-v w Huwuwwwmmmm. ly f 4 .mw

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withdrawing distilled solid particles f from the lower portion thereof into a vertically upwardly flowing stream of hot combustion gases, obtained as set forth below, passing the resultant mixture in a conned vertical straight line path upwardly through said distillation zone to the top portion of a downwardly moving bed of solid particles within a burning zone superimposed above the distillation zone, introducing a free oxygen-containing gas stream'to the lower portion of the burning zone and thereby burning substantially the residual carbonacecus content from the solid particles and heating the residue, removing combustion gases formed in the burning step from the upper portion of the burning zone while transferring heated residual solid particles from the lower portion thereof into direct contact with water in a confined cooling zone whereby the residual particles in the latter zone are cooled and high temperature steam is generated, and subsequently introducing a stream or the steam thus generated to the lower portion of the distillation zone as the aforesaid high temperature steam.

`-It is also a particular feature of the present process to supply free oxygen-containing gas to the stream of solid particles being passed up Wardly in the straight line path and `thus employ` two distinct stages of burning carbonacecus material from the distillation residue, incomplete combustion of the carbonacecus content of the solid material being effected in the confined straight line path or riser conduit during the.

upward concurrent flow of gas and distilled solid particles from the lower portion 'of the distilling zone to the upper portion of the elevated burning zone while the combustion of the carbonaceous residue from the solid particles is completed in the elevated burning zone during countercurrent contact of the downwardly moving solid particles therein with a second oxidizing gas stream. The path of the rising material in the riser conduit or first combustion zone,pro

Vides a means for transferring heat indirectly to the distillation zone. The riser conduit defining a conned straight line path of shortest distance between the bottom portion of the distillation zone and the upper portion of the elevated enlarged burningzone provides structurally a passageway adapted to reduce erosion and iiow resistance to a minimum. After the combustion in the enlarged burning zone, the hot substantially incombustible material is readily utilizable as a means for generating steam and in a preferred mode of operation is therefore passed to a confined cooling or steam generating zone wherein it is contacted with water so that it is cooled prior to its discharge from the unit and thereby generates steam which is utilized in the distillation.

A more specific embodiment of the present invention comprises continuously passing solid hydrocarbonaceous material in a finely divided form to an elevated portion of a confined distillation zone and introducing high temperature super-heated steam to the lower portion of this zone in an amount and at a velocity sufficient to fluidize the solid material therein, discharging mixed vaporous distillation products and steam from the 'upper portion of the distillation zone, withdrawing distilled solid particles from the lower end of the distillation zone in a rst annular column and commingling the thus withdrawn particles with a vertically upwardly flowing gasstream,.comprising hot combustion gases. obtained as'- hereinafter set forth, passing the resultant mixtureupwarclly through a coniined vertical-'straight line path extending through said distillation'zone and to the upper portion of a burning zone maintained vertically above the distillationv zone and discharging the solid particles of the mixture from the vertical path onto the top portion of a descending bed of solid particles in the burning zone, passing a free oxygen-containing gas stream upwardly through the solid particles' in the burning zone and effecting the substantially complete burning of the carbon aceous content from the solid particles while maintaining the descending bed in a fluidized state, continuously discharging hot combustiony gases formed in the burning step from the upper portion of the burning zone and the hot residual solid particles from the lower portion thereof in a second annular column, supplying a stream of the aforesaid hot combustion gases to the dis,-

tilled solid particles issuingV fromwthe first an` nular column, passing a stream of the hot resi-- dual particles issuing from the second annular column into direct contact with water in a con? fined cooling and steam generating zone to quench the hot solid particles vand simultaneously produce high temperature steam, and passing a stream of the thus4 produced steam'tol the distillation zone as the aforesaid :high tempera' ture s team.

In still another specic embodiment of the invention, hot combustion gases from the burningzone are passe'din indirect heat exchange relationship with steam produced in the aforementioned cooling or steam generatingzone in a manner to highly superheat the steam prior to its introduction to the distillation zone.` It is also contemplated that a portion of the hot combustion gases from the burning zone may be mixed in controlled proportions with air or free oxygen-containing gas stream and the resultant gas mixture utilized to transport the distilled solid material from the lower portion of the dis tillation zone to the upper portion of the elevated burning zone, whereby this transport is effected by a transporting gas stream which has an elevated temperature and a controlled free oxygenv content less than that of airn and adapted to regulate the amount of burning in the riser conduit, while the transporting gas stream is atthe same time made available in the proper amount required for continuously transferring the distilled solid particles. y Y

A particular advantage resides in the improved operation utilizing the two stageburning of the carbonacecus material remaining on the distillation residue and the ow ofthe hot material in a vertical coniined path upwardly through the distillation zone in a manner providing heat transfer indirectly to the distillation zone. Another advantageous feature` ofthe present operation is the use of a portion ofthe hotburned ash from the burning zone to mix with "the bonaceous material and to thereby dilute and preheat the latter at the upper portion of the distillation zone and aid in-maintaining it in nely divided and freely owing state. Still another. feature of a preferred embodiment of the invention is the maintenance of a continuously replenished body of water in the lower portion of the residue cooling or steam generating zone in order that the -incornbustible solid residue of the shale, or other carbonaceous material, may be cooled by direct quenching and then discharged as a slurry while simultaneously a portion of the water is vaporized and passed upwardly through the steam generating zone countercurrently to the hot subdivided solid ash or residue descending therethrough.

In a preferred embodiment of this distillation method, superheated steam is used as the gasiform heating medium in the distillation zone, fractionation of the vaporous and gaseous products removed from the distillation zone being.

greatly facilitated thereby. Without, however, departing from the principal objects and features of this distillation method it is also contemplated as one mode of operation thereof to employ a gasiforrn heating medium other than steam, provided such medium is substantially de'- void of free oxygen at the time of itsintroduction to the distlling zone. Thus, a hydrocarbon gas from an extraneous source or preferably a light gas fraction, which has been separated from the fluid distillation products removed from the distillation zone and usually contains light hydrocarbons such as methane, may be..

heated to asuitably elevated temperature, gen erally substantially above the average temperature prevailing in the distillation zone, and thensupplied to the lower portion of the latter as the gasiform heating medium. The hydrocarbon gas, when used in this manner, may be heatedv the manner herein provided, hot combustion -f gases substantially devoid of free oxygen are readily obtained by effecting the burning in the downwardly moving relatively compact bed of solid particles in the elevated burning zone and medium to the lower. portion of the distillation zone and into direct contact with the finely di*` 0 vided charge undergoing distillation therein.

This mode of operation permits dispensing with theindirect heat exchange between hot combusgasiform heatingv media and tion gases and other when this mode of operation. is used', at least -enters the distillation zone.

portion -`of the heat contained-fin 'the highly heated residual solid particles issuing from the burning zone may be recovered in the form ofhigh temperature steam obtainable in the aforementioned steam generating zone and utilizable for effecting the fractionation of the mixed fluid :distillation products and combustion gases dis-- charged from the distillation zone; Thereby,

the heat requirements of both the distillationand the fractionation of the distillation products can be satisfied entirely by the heat generation in the burning operation of the present method.V

In some instances it may be desirable to mix a stream of high temperature steam with a stream of the hot, substantially oxygen-free combustion gases and introduce the mixed streams as the gasiform heating medium to the .distillation zone.

In all of the herein described modes of operation a stream of the highly heated residual solid particles withdrawn from the burning zone may be supplied to the distillation zone in proximity to the point of introduction of the finely divided solid hydrocarbonaceous material to the latter zone. vSuch stream of the highly heated particles may be introduced directly into the upper portion of the bed of solid particles in the distillation zone or, preferably, into the stream of the solid fresh charge immediately before the latter One advantage of utilizing hot residual particles substantially at the temperature of their discharge from the.

burning Zone in this manner resides in the rapid heating of the solid charge particles through a temperature range within which they ordinarily zone, the heat supplied thereto by the hot.

,residual particles constituting, in general, a

-minor but` readily variable and controllable portion of the total heat requirement of the distillation, a major portion of which is preferably supplied by the gasiform heating medium in all of the aforesaid modes ofoperation. It is understood, of course, that another minor portion of said heat requirement may be furnished to the bed of solid particles in the distillation zone by indirect heat transfer thereto from the vertical :straight line path or riser conduit, more particularly when effecting a partial combustion of the carbonaceous components from the distilled solid particlesI in the riser conduit.

An important advantage of the present. dis-l tillation method resides in the elevational coordination of the principal processing zones. which permits .the handling of the hottest solid particles without any conveying means in the form of mechanically moving parts or gas lifts y and thereby assures greatest possible life of the apparatus parts coming in contact with these particles and greatest possible heat conservation. Thus, and because. of the finely divided state in which thev hot residual particles are obtained under the processing conditions of the present method, these highly heated particles can be directedby their own gravitational iow in a genorally downward direction fromfthe lower pori tion of the elevated burning. zone into the coolf ing zione or" steam generator, or in .controlled streams both into the cooling zoneA and the upper 'portion of the distillation zone, through conduits of minimum dimensions. When passing hot residual particles from the burning zone both to the cooling zone and the distillation zone, the portion supplied to the latter is preferably smaller than that directed to the former in the present distillation method. The elevational coordination herein described also has the advantage of permitting the greater portion of the apparatus requirements to be grouped in a compact processing area on ground level with a minimum of structural framework for the support of elevated equipment.

Additional advantages and features of the present improved distillation operation will become more apparent upon reference to the accompanying drawing diagrammatically illustrating one form of apparatus suitable for practicing the invention and the following description thereof. While the treatment of oil shale is generally referred to in the following description it isto be understood that other hydrocarbonaceous materials such as coals, torbanite and tar sand, and in general hydrocarbonaceous solids of the kind yielding a carbonized residue upon dry distillation and an incombustible residue upon combustion may be treated in the present process in a manner analogous to that herein described for oil shale. y

Referring now to the drawing, there are indicated hoppers I suitable to store raw or dried comminutated shale or other solid hydrocarbonaceous material. Each of the hoppers I has an outlet conduit 2 with a, feeder or control valve 3,' suitable to regulate the 'ow of the solid material and assure its continuous feeding into the line 4. Conduit 4 connects with the side of a distillation chamber 5 at an elevated portion thereof, to which the finely divided material is charged and wherein it travels downwardly in a relatively compact or fiuidized bed while being contacted with high temperature steam introduced to the lower end thereof by way of line An aeration line 1 with a control valve 8, connects with the feed conduit 4 and is available to supply steam to the finely divided material prior to its entrance into the distillation chamber 5. The steam supplied through line l may preheat the solid material, but is desirable primarily for maintaining the material in lines 4 and 2 in a movable state and insuring that it readily iiow into the distillation zone. Instead of steam, another substantially inert gas, such as :for example a stream of the combustion or nue gas issuing from the heat exchanger 40, described below, may be supplied to line 1 for the same purpose.

High' temperature steam or other gasiform heating medium is charged to the lower end of the distillation chamber 5, through line 6, at a temperature of the order of from 450 C. to 750? C. and in the case of most shales preferably at about 50G-650 C. and is passed countercurrently to the descending solid material in this chamber in an amount suflicient to maintain the bed of solid material in a freely owing state and preclude agg-lorgneration of solid particles.

Fluid distillation products, substantially in a vaporous state, accumulate in admixture with the used gasiform heating medium in the upper portion of the distillation( chamber and this mixtureV is passed through particlel separator 9 to be discharged through the outlet conduitv I0 and a'pressure regulating valve therein to a suitable fractionating and recovery systeml notI shown in the drawing'. Retained solid particles are returned from the lower end of the separator 9, through dipleg I I to the bed of solid material in the lower portion of the chamber '5.

The distilled shale particles are withdrawn from the lower portion of the chamber 5 through the lower leg I2 in an annular column around a centrally positioned conduit I3, at thelower end of which the particles are caused to change their direction of flow to then pass upwardly through the riser conduit I3 to an upper contacting or burningI zone within chamber I4, Which is hereinafter referred as burning chamber and which is superimposed above the lower chamber or distilling retort 5. At the bottom end of the withdrawal leg I2, a line l5 projects into the interior thereof and terminates at the lower end of the internal riser conduit I2. Line I5 is provided for introducing a gas stream into the lower end of the riser conduit to entrain or commingle with the finely divided distillation residue and to transport it to the upper portion of chamber M. Hot combustion gases, obtained as subsequently described, or when desired a free oxygencontaining gas stream, such as a mixture of air and hot combustion gases, is passed through line i5 into the riser conduit I3. A valve I6 in the line I5 provides means for controlling the amount of free oxygen-containing gas entering the riser conduit from an external source. A valve 65 in line 56 serves to control the supply of recirculated hot combustion gases through line I5 to the riser conduit, as more fully described below. Y

The regulation of the total amount of gas passing through line I5 into the riser conduit affords, in conjunction with the valves 3, a means for controlling the quantity of solid particles `present in the distilling retort.

In the usual oil shale distillation operation there is a certain amount of carbonaceous material still persent in the distilled particles, such that by the addition of air or oxygen to the hot distillation residue an oxidizing and burning operation takes place. In the operation of the present process either no burning or only a partial oxidation and removal of this carbonaceous content is effected in the vertical riser conduit and accordingly, when partial oxidation is to be effected, the freeoxygen content of the gas supplied through line I5 is controlled and generally is maintained at less than that of air. The complete removal of the carbonaceous content is effected in the burning chamber I4, where the nal temperature of the particles can be controlled readily and closely. A free oxygen-containing gas stream, preferably air, is supplied to the lower end of the burning chamber I4 through line Il, having a control valve I 8, and passes upward- Y During the partial burningstep in the riser conduit I3, the solid particles are carried in suspension in the ascending gas stream of controlled, relatively low concentration of free oxy- .Whenever the carbohacbus 'matter on the solid 1l een. tri. .en lt,..th sono parliuoie's aerei corvo arci-y bea of substantially 'greater cnpactss, density, or solids Concencontrasting conditions and oy'gen coh- 'oenti'atons in the t'vo .steps applied in one of the embodiments or the-present invention -fgatio of 'the tree. oxygen content in yeach of the .gasst'ams 'Supplied to the two hui-ning steps "with 'formation of v.combi's'tic''ngases o? minimum vc'fitent f'eces's oiiy'gl and haimurn'content or heeft m conjuro. ionivit'h'substantaiiy oomn vplete combustion o' the carbonaceous content of `the distillation residue; fmOrem/er, the-combusjtion gasell disengag frornfthe suspen'sion upon Aits discharge from the riser conduit 'i3 into the flipper portion of the 'chamberi on the one hand one 'non the tooo'f ine been; this chamber on the other at substantially equal temperatures .one o balan'oetumiog .operation of high efficiency is securedyiith avfminimu'm .of apparav: requirements.

'particles 'issuing fronthe lower end ofthe vdis- Stilling .retort 5 is AnsufI'c'ient yfor furnishing, b y the burng 'thereontheheat requirements of theprocess, additional heat maybe generated by the bluni'ng fof fuel from -an external source .of l

:supply in the burning `'ope`ration already def'scrib'e'd. For this purpose, burner port I9 is ,provided at a sit'able poiht of the lower periphery of the burning'. chamber 14, and `if so dosired ltito or "more 'of suchjourner p r`J`1 ts -ir1ay be spaced at ,suitable .points of the wall of chamber :IML The burherport s rendered .pressure-tight, Lrelatively'to the v"atrio'splfrere surrounding the chamber I4, ,and uel or loothr fuel and airare supplied .to thetuioerjport la through .vaivectroll'ed lines 2`D 2] respectively, according t requirements. supplying only7 fuel through theblzrn'er.Y rt I9', oxygen for its com I`9 `so 'as to 'rndr'th operation self-supporting.

The tornei-:port it, moreover., fof oaruoular ouvaotogo'in ,storting 'ure operation or .the ign-o oT ess'. [For thisuroosefsubotannany Linoomusubio solid particles 'are circulated through the system comprising chamber .5. lse'r conduit I 3 and chamber 'f4 with the ald o line "2i and valve and with ircnatibn- .of 'gas "through xthe reoirculating ripeta "and valv 553 inbre'riihy described below). Wil-ele th'rli "IS 2U 'd' is effected, at leas-t in aforesaid oitmooosfoei to rhodburoor port meteor lli) the circulating materials obtain' aA sufficient temperature to permit feeding of comminuted oil shale or the like charge through line 4 to the retort 5 at a .gradually increasing rate, with commensuratel'y increasing removal of solid particles thro-ugh line 2li, kdepending on the nature .ofthe charge and the -distilled particles, Whereafter the system is kept on stream Vfor an extended ,period .of time, which .may amount to many months and is determined primarily by factors of safety in sp'ectionand repairs necessitated -by ordinary 'wear of the equipment. Combustion in the start- ',ing-upoperat'ion may be initiated in the .burner port fill by suitable ignitingmeans, not show-n in thedrawingyorby chemical ignition. v

v Referring again to the normal operation of the process,A the ashor residual, incombustible solid material obtained upon the complete oxidation .an-dneating .to the required temperature is withdrawn as a downwardly -rnoving annular column .from the lower end of chamber Ill through the leg 2.2 which surrounds the internal riser condui-t 'i3 and which has outlet conduits l23 andf24 connecting therewith. l A major portion of' the hot shale ash obtained in chamberll is transferred to a cooling vcharnber 2755 through line 23 VIhaving control valve 12-5, and in this latter chamber the shale; ashis contacted and quenched with an inert fluid, `suchjas a light hydrocarbon gas or Water supplied at the lower end thereof. Where a gasiiorm heating medium, other than steam is to be utilized for supplying heat for the shale distillation, the Ine-.- dium is introduced to the heating chamber 2,5 through Aline $3, having Valve 64. For example, a .hydrocarbon gas as here'inbefore referred to,or alight gas fraction separated from the fluid distillation products of the present process may thus be supplied through line $3. `-In the embodiment illustrated, Where water Ais `used as the quenching medium and a source of high temperature steam, Water is supplied through line 2l to the lowerend of the .chamber 25. .An outlet-leg 28 and a dischargernechanism or outlet valve 2Q passes the residual material, usually at -a temperature not exceeding [100 C., into -a body of yWater main? tained Within the chamber il. The quenched and cooled shale :ash Yis further cooled in this body of Water, being. discharged -from the tank by vmeans of a conveyor 3l. In a preferredmode of operation, Water ispassed tothe interior lof tank or chamber Sli through Yline 32 and .thecontrol valve and is Withdrawn from thefupper end 'thereo'll through Aline 31B .having .valvev 35, being subsequently passed through circulating pump BE to line 2l, Which supplies Water tothe lower end of the 'chamber f2.5. Thus, the now of the Water `stre'a'n'i is such that itis gradually raised 'in temperature prior to its Yreachingchaine ber 25,; thereafter, and as it passes upwardly cot'intercil'rrently to theshale ash and. residue descendingin chamber 25,4 the "Water is vapori'zed andthe temperature of the resulting steam finally approaches that ol. the high temperature solid material entering the upperportion. of .the zone. In 'order 'to preventfthe carrying away, of shale ash with the steam, a particle separator v3l is placed Within'the 'upper ,portion of. the .chamber 2 5. and serves to` return the solid particles through dropleg '38 tothe downwardly moving bed of material, and a stream of high temperature steam substantially free of solid particles is discharged from the upper end of the chamber through line 39.

A heat exchanger is provided to add superheating to the steam or other gasiform heating medium prior to its being introduced through line 6 to the distillation retort` I-Iot combustion or flue gases from the burning chamber I4 are transferred by way of conduit 4 I, having control valve 42, to the heat exchanger 40. As in the chamber 5,\a particle separating apparatus 43 is placed within the upper portion of the burning chamber I4 in order that the ue gases may be discharged -from the upper end of that zone substantially free of solid particles, while recovered and collected 'particles are returned to the downwardly moving bed within the chamber I4 by Way of dipleg 44. The hot flue gases passing through the heat exchanger 40 in indirect heat exchange relationcharged with the hot combustion gases from the burning chamber I4. In this embodiment a regulating valve 45 is placed in line 6 at a point just beyond the heat exchanger 40, and in addition a line 51 with valve 58, is connected to line 6 to provide means for withdrawing excess heating medium from the unit, or for supplying superheated steam to the fractionation system for the iiuid distillation products, as hereinbefore described, and to various points of the system where high temperature steam is desired as aeration or stripping medium.

As is customary with moving bed and iiuidized processing operations, it is desirable to provide stripping steam, or other inert gaseous medium, at each of the solids Withdrawal zones for each of the contacting chambers. At the bottom of thedistillation zone is a line 46, having a control valve 41, connected to the withdrawal leg I2 so that steam from line 5l or other inert stripping medium may be introduced to thel withdrawal leg to prevent the entrainment of valuable uid distillation products by the distilled solid particles. Likewise, steam is also passed to the Withdrawal leg 22 which passes heated particles from the lower end of the burning chamber I4 to the steam generating zone 25. Preferably, and as illustrated in the drawing, superheated steam is supplied to the Withdrawal leg 22 by way of line 48 having control valve 49, the line 48 being connected to and supplied with steam from line 5 Y just beyond the heat exchanger 40. Thus, high temperature superheated steam is utilized at this point for the dual purpose of both precluding entrainment of oxygen in the solid particles passing to the steam generating zone, and preventing undue cooling of these particles. For analogous purposes, and for the purpose of assuring ready flow of the solid particles, superheated steam may also be introduced through suitable connections (not shown in the drawing) from line 51 into line 24 (more fully referred to below) at a point in proximity of the valve 52 on the upstream side of the latter. A line 5I] with valve 5I is also provided at the conduit 23 for the supply of a hot gasiform aerating medium, such as steam from line 5l', in order that the solid material may if necessary be aerated and its gravitational flow facilitated as it passes from the burning zone into the cooling or steam generating zone 2'5.

A desirable feature of the improved shale procing the stripping zones `I2 and 22 of an annular shape and positioned uniformly around the central riser conduitI I3 in heat exchange relationship therewith, since the higher the temperature, the more efficient'is the stripping. Though not indicated in the drawingit is contemplated that if desired, flow distributing 'grids or vertically spaced horizontal perforated plates may be positioned around the riser conduit in each of the stripping zones I2 and 22. 'A y v Referring now tothe line 24 having valve 52, it may be desirable during'the normal operation of the process to continuously'pass a portion, generally a minor portion, of the heated particles issuing from the lower endof the burning chamber I4 into the feed conduit '4 in order that the hot shale ash may commingle with the fresh comminuted shale charge vand preh'eat the latter immediately prior to its entrance into the distillation zone of chamber 5. This method of operation also permits a given quantity of hot `ashlike material to be present within the moving or iiuidized bed-of chamber 5, whereby a dilution effect is obtained counteracting the baking tendency of the'fresh'shale particles particularly during an early stage of their'distillation'.

One of the important features in the ,operation of the present process' is the recycling of a portion o f the hot flue gas streamsubstantially at its temperature of discharge from the burning chamber I4 through line 4| tothe line I5 which enters the withdrawal leg I2 'atthe bottom of the distillation zone and chamber 5.v Conduit 53, with valve 54, serves to connect the line 4I with pump or blower 55 and the line 56 which in turn discharges through control valve into line I6 whereby flue gas may be used as' the medium for transporting the particles through riser I3 to the burning'chamber -I,4,or, alternately, for both this purpose and as a diluent to mix with air or other oxygen-containing` gas'lstrelam entering the lower end of the verticalriser conduit I3: The supply of a portion of hot spent or substantially oxygen-free combustion gases from the top -of burning zonenI4l'through'thelinej53, `thus provides an advantageous means for not Vonly precluding the loss of sensiblei heat', from the "distilled solid particles duringtheir transfer, lto the burning chamber, 4but actually' increasing 'the temperature of this'stream of solid particlesjand it alsoprovides an advantageousmeans for obtaining, upon admixturev with air supplied through line I5 and valve I6, a preheated gas stream of controlled oxygen content lower than that of air. The connecting line 59- and valve 60 provide means for passinghot combustion gases, substantially devoid of'free oxygen, from the line 56 to line 6, whereby thev combustion gases may serve as gasiform heat-supplying I nedium being charged to the distillation chamber 5. It should be understood from the foregoing, however, that in the preferred mode `ofoperation, lthe recirculated combustion gases jare'not passed into the distillation retort itselfor into contact with the distillation charge and that in Iany event the recirculated hot gases provide 'a desirable transporting medium or a diluent for the air entering line I6, and a hot gas stream adequate in quantity for transporting the distilled particles through the conduit I3 to the burning ychamber I4. A line 6I with valve 62, connects with` line 4I near the top of the combustion lchamber I4 and provides means for venting the air 'system at the starting-up'-and 'termination o f an operation as een for withdrawing not complici-,ion gases in such amounts as are not required within the illus= trated systei'n during its operation,

In` the process as describdf the iolintei'cuil low ol' gaseous hea-ting medium anti liely divided solid in the distillation acne materially benefits ine'- valuable hydrocarbon cil fractions desired as priinaiy products oi the process and reduces to a minimun the undesirable cracking or pyrolytic decomposition reactions which would result inv excessive gas formation. Crack-ing will take place rto seine extent in the lower hotter porn tion of the distilling chamber S while primarily a noni-destructive distillation takes place in the upper or relatively cool portion thereof;

in carrying outthe process, .the temperature distributionin the d'stilling Zone 'or retort 5 will depend' largely on the initial composition. oi the solid. chargeand to some extent also 'on the exs tent ofturbulency which will be greater in a well nuidized bed relative to a more coinpact bed, but in either case' such temperature distribution is suicient to carbonize tarry components 'of the solid particles so as to permit the 'distillation resi-Y dueto .remain in a finely divided state for its l.

transfer into the riser conduit i3 and there through to the upper portion oi chamber I4 the combustion zone inthe latter. Most oi the commonly available oil shares are distill'able in thepresent process at temperatures of the solid particles of. from about 425. to about 500 C., and the maximum temperature of the solid material in the distillation chamber 5 is seldom required to exceed about 550 C. As a rule, a temperature substantially above the average temperature pre; f

vailing in the retort 5 andA less than 750 C.,- and more particularly of from 500 to 650 C. will be ample for the steam or other gasiform heating medium to effect the distillation of mostkinds of oil shale anrl torbanite at a suitable ratio vof sol-id material to gasiform heating medium* A relatively low heating medium temperature and ayhigh ratio of the medium to solid vcharge are desirable for a maximum recovery of hydrocarbon oils, whereas the higher temperatures andV rela tively lower ratios of gasiforrn heating medium to solid charge may `beernployed. when it is pre-'- ferred to -sacriceototal yield of oilxin` order to obtain primarily vlow boiling hydrocarbon oil fractions. In the latter -case the solid particles will movey essentially as acompact bed down wardly through retort -5 countercurrently to suf"- ficient gasiform heating medium to preclude kbaking or agglomerating of the vshale particles and the highest boiling volatilizable components of the oil shale, or other bituminous solids, will be retaineolin the distilling retort and will'eventually be cracked into `lower boiling k'components and carbonace'ous or non-volatilizable residue. High temperatures of the vsteam or other gasifornl heating medium and high ratios of the medium toi solid charge, that is to say ratios of gasiform medium to so-lid particles ysuch that the descendnig nedy in the distan-ng retort is maintained in a well fluidiae'd dense phase and a -dilute phase ofconsiderably lower concentration of solid particles is maintained above the bed, are generally preferred for optimum recovery of normally liquid hydrocarbonaceous distillation products.

The process may be operated under any suitable pressure and normally will be carried out atabout atmospheric or a moderate Isupere-atmospheric presslrrmup to yabout atmospheres, although it jniay in some 4cases be desi-red to operate meer his'gerrprssure iso, to permit relatively sinall diniensioning ci the apparatus for a given tin "ughput of materialani-to permit obtaining 'steam under relatively high pressure. Slight pressure differentials will ot cou-rse exist between the different .zones-ori the in order that adequate oW o materials may be made from one sone to anoniem` In the apparatus illustrated in the drawing continuousI new of the solids and particularly gravitational new oi the hot residua-l material from the burning zone isgifeatly facilia taies by the @inerenti elevations of the elements l, 5, l l and i5; relative to other The neness to which fresh shale is pulverizea ground 'will depend somewhat on economic considerations andas to 'the exact contem-plated operation or the Particle airain-. 'eters or greater than 5 millimeters are generally unclesiredin the present method., Where a fluid, izeadense phase operation Vis desired the uis. till'ation zone or the b 'ng' chamber or in both, a particle size of; approiriniateiy trein c 'l to 0.8 millimeter in diameter is preferred for the hyere-V earbonaceous charge; .however with a moving: bed type of operation, a particle size or from approio imately n.1 to about 3io rnillinietersfin diameter is generally utilizable, and with su'iiiolent` transporting gas the resultant distilledparticles may in either 'case be napster-'red without' diiliculty from thek lower end of the distillation. retort E to the upper portion oi the burning 'chamber t4.

When itt is desi-red to produce a maximum amount of` high temperature steam within kthe residue cooling or steam generating' zone 25, a relatively high temperature should. be maintained in the upper buming zone within chamber it. Normally, the residual solid particles may be heated to a temperature oil theorder of. 600-'7'50 without sinterine some-oil Ashales yield residues which permit heating tuv temperatures of the order of 800 C'.. without 'sinte'ring However, the highest temperature in chamber I4 should always be- `kept a sufficient amount, that is vat least about 25 C1.,.below the temperature at which the ash-like residue tends toz-sinter yor clinker, and such temperature depends on the particular hydrecarhonaceous charge treated: and.. can be determined i-'ea-dily :by laboratory tests on a sample Aof such: oh-argeprior' to treatment "or the latter inv the present process .ns hereinbeiore noted, where the distillation resi-dueI in the chainsber lil has insuificient carbonaceous content t0 burn and raise the mater-rail at least to the prefferr'ecl temperature which is of theorder of 600 to 675 C., vor., if sodesiredz, tov-a1 higher :permissible temperature to about Aor 800 C. then ad ditional heat may begeneiiated bytsupplying sufnoi-enteXtraneousruel-or combustible-byeprodocts of the process to the bur-ner port itil, so ithat lthe heat and steam lrequirernents oil the process will be met. The heateconoiny of. fthisfprocessis inaterially enhanced ythcrolli-lilly insulating @the retort 5,- the combustion chamber i4, the residue cooling chamber 25, and the variousfconnectihg conduits external -to these-chambers and carrying high VVtemperatin-.e-strearnsvso as elio-limit loss oi heat le-y vradiation toa minimum. v'li-lieattransu ier from the-central riser'lconfduit t3 may be in creased-by providing. it Aon :itsoufter wallalong -the portion Athereof `w-itl'iin the 'retort 15', and, more particularly the ,portionicominginto contact vwith the descending leed in ythis retort, withpreferably longitudinal yfins yof =metallic material, 'and heat equalization between' Ithe lupper iportion ioioontl-uit i3 andI the bed -surromjiding itchamber Heiney; @similari-y; iosterediibil longitudinal ruis along the. latterportion. Heat contained in the combustion gases withdrawn from the system through lines 6I and/'or discharged at lowered temperature from heat exchanger 4B may be utilized with considerable advantage in the drying of the shale charge prior to supplying the latter to the distillation retort 5. Such drying may be effected after comminution of the solid material, if so desired, and in any event should be carried out in a manner assuring the maintenance of the solid charge at temperatures below about 200 C. duringV the drying operation.

I claim as my invention:

l. A method for distilling solid hydrocarbonaceous material which comprises continuously -passing said material in finely divided form downwardly through a conned distillation zone and therein contacting said material with an upwardly ilowing gasiform heating medium substantially devoid of free oxygen, discharging mixed iiuid distillation products and heating medium from the upper portion of said distillation zone and withdrawing a stream of distilled solid particles from the lower portion thereof into a vertically upwardly iiowing gas stream comprising hot combustion gases, obtained as hereinafter set forth, passing the resultant mixture in a confined vertical straight line path upwardly to the top 4portion of a downwardly moving bed of solidjparticles. maintained in a confined burning zone superimposed above said distillation zone, said conned straight line path extending through and in indirect heat exchange with said material in the distillation zone and said bed of solid particles in the burning zone, introducing a free oxygen-containing gas stream to the lower portion of said burning zone and thereby burning substantially the residual carbonaceous content from the solid particles in said downwardly moving bed, continuously removing hot combustion gases formed in the burning step from the upper portion of said burning zone and hot' residual solid particles from the lower portion thereof and supplying a portion of said hot gases to said stream of distilled solid particles withdrawn from the distillation zone, passing a stream of the hot residual solid particles withdrawn from the burning zone in a generally downward direction substantially by its own gravity and at its temperature of discharge from said burning zone into a cooling zone and therein contacting the same with water so that said stream of residual particles is cooled and high temperature steam is generated, passing steam thus obtained into indirect heat exchange with a second portion of the hot combustion gases removed from the burning zone and thereby superheating the steam to a temperature substantially above that prevailing in the distillation zone, and introducing a stream of the thus superheated steam as said gasiform heating medium to the lower portion of said distillation zone. Y 2. A method for distilling solid hydrocarbonaceous material which comprises continuously passing a stream of said material in finely divided form downwardly through a conned distillation zone and therein contacting said material with an upwardlyiiowing gasiform heating medium substantially devoid of free oxygen, discharging mixed fluid distillation products and heating medium from the upper portion of said distillation zone and withdrawing a stream of distilled solid particles from the lower portion thereof into .a vvertically :upwardly iiowing free 16 oxygen-containing gas stream, partially burning carbonaceous components from the distilled solid particles while passing them in admixture with said oxygen-containing gas stream in aconiined vertical straight line path upwardly to the top portion of a downwardly moving bed of solid particles maintained in a confined burning zone superimposed above said distillation zone, said coniined straight line path extending through and in indirect heat exchange with said material in the distillation zone and said bed of solid particles in the burning zone, introducing another free oxygen-containing gas stream to the lower portion of said burning zone and thereby burning substantially the residual carbonaceous content from the solid particles in said downwardly moving bed, continuously removing hot combustion gases formed in the two burning steps from the upper portion of said burning zone and hot residual solid particles from the lower portion thereof, passing a stream of the hot residual solid particles withdrawn from the burning zone in a generally downward direction and substantially by its gravity and at its temperature of discharge from said burning zone into a cooling zone and therein contacting the same with water so that said stream of residual particles is cooled and high temperature steam is generated, passing steam thus obtained into indirect heat exchange with a stream of hot com-v bustion gases removed from the burning zone and thereby superheating the stream to a temperature substantially above that prevailing in the distillation zone, and introducing a stream of the thus superheated steam as said gasiform heating medium to the lower portion of said distillation zone.

3. A process which comprises contacting iinely divided solid hydrocarbonaceous material with superheated steam in a distillation zone, removing residual solid particles from said zone and suspending the same in a gaseous transporting medium, transporting said residual particles in suspension in said gaseous medium to a burning zone, burning carbonaceous matter from the residual particles in the last-named zone, removing the resultant combustion gases from the burning zone and utilizing a portion thereof as at least a part of said transporting medium, withdrawing hot solid particles from the burning zone and discharging the same into a body of water, thereby generating steam, passing the latter in indirect heat exchange with another portion of said combustion gases to superheat the steam, and introducing the superheated steam to said distillation zone. 4. The process of claim 3 further characterized in that said gaseous transporting medium contains oxygen and in that sai-d residual particles are subjected to partial combustion while in transit from the distillation zone to the burnmg zone,

5. A process which comprises contacting iinely divided solid hydrocarbonaceous material in a confined distillation zone at a distilling and carbonizing temperature with upwardly iiowing combustion gases produced as hereinafter set forth, discharging mixed gases and vaporous -distillation products from the upper portion of said distillation zone, removing carbonized solid particles continuously from the lower portion of said distillation zone and suspending them in a gaseous transporting medium, transporting said carbonized particles in suspension in said gaseous medium to-a Separate conned burning zone andyfrom the lower portion of said burning zone and said combustion gases from the upper portion thereof and utilizing a portion of said combustion gases as at least a part of said transporting medium, commingling said hydrocarbonaceous material with a stream of said withdrawn hot residual particles at substantially the temperature of their removal from the burning zone and at a rate at which only a portion of the heat requirements for the distilling and carbonizing of said hydrocarbonaceous material is supplied by said stream of residual particles to said distillation zone, and introducing another portion of said combustion gases substantially at their temperature of withdrawal from said burning zone into the lower portion f said distillation zone at a rate sufcient to introduce thereto the remaining portion of said heat requirements.

6. A process which comprises continuously passing finely divided solid hydrocarbonaceous material downwardly through a confined distillation zone and therein contacting the same at a distilling and carbonizing temperature with upwardly flowing combustion gases produced as hereinafter set forth, discharging mixed gases and vaporous distillation products from the upper portion of said distillation zone, withdrawing distilled and carbonized solid particles continuously from the lower portion of said distillation zone and passing them in a restricted stream into an elevated portion of a separate confined burning zone, supplying an oxidizing gas to the lower portion of said burning zone and therein burning residual carbonaceous matter from the particles so that combustion gases practically devoid of free oxygen and having a substantially higher temperature than said distilling and carbonizing temperature are formed, continuously discharging said combustion gases from the upper portion of said burning zone and hot residual particles from the lowerp0rtion thereof, commingling said hydrocarbonaceous material with a stream of said withdrawn hot residual particles at substantially the temperature of their removal from the burning zone and at a rate at which only a portion of the heat requirements for the distilling and carbonizing of said hydrocarbonaceous material is supplied by said stream of residual particles to said distillation zone, and introducing a stream of said combustion gases substantially at their ternperature of withdrawal from said burning zone into the lower portion of said distillation zone at a rate sucient to introduce thereto the remaining portion of said heat requirements.

7. A process which comprises contacting finely divided solid hydrocarbonaceous material in a confined distillation zone at a distilling and carbonizing temperature with an upwardly flowing stream of combustion gases produced as hereinafter set forth, discharging mixed gases and Vaporous distillation products from the upper portion of said distillation zone and withdrawing distilled and carbonized solid particles continuously from the lower portion thereof into a transporting gas to form a suspension of carbonized particles in said transporting gas, passing said suspension in a restricted stream upwardly through an elongated passageway to the top pori8 tion of adown'wardly moving bed of lsolid particles maintained in a confined burning zone .of higher elevation than that of said distillation zone, introducing a free oxygen-containing gas stream into the lower portion of said burning zone and regulating its rate of supply to said downwardly moving bed so that carbonaceous material is.. burned from the particles therein with .the formation of combustion gases practically devoid of free oxygen and having a substantially higher temperature than said distilling andv `carbonizingtemperature, continuously removing the resultant hot combustion gases from the upper portion of said burning zone and commingling a stream thereof as at least a major portion of the aforesaid transporting gas with said particles being withdrawn from the distillation zone, flowing a restricted stream of hot residual particles in a generally downward direction from the lower portion of said burning zone substantially by gravity and substantially at `its temperature of discharge from said burning zone into said nely divided hydrocarbonaceous material, maintaining the flow of said stream of residual particles at a rate to furnish only a portion of the heat requirements for the distilling and carbonizing in said distillation zone, and introducing another stream of said hot combustion gases substantially at their temperature of withdrawal from said burning zone into the lower portion of said distillation zone at a rate sufficient to introduce thereto the remaining portion of said heat requirements.

8. A process which comprises contacting finely divided solid hydrocarbonaceous material with a superheated gasiform distilling medium in a distillation zone, removing residual solid particles from said zone and suspending the same in a gaseous transporting medium, transporting said residual particles in suspension in said gaseous transporting medium to a burning zone, burning carbonaceous matter from the residual particles in the last-named zone, removing the resultant combustion gases from the burning zone and utilizing a portion thereof as at least a part of said transporting medium, withdrawing hot solid particles from the burning zone and discharging the same into a particle cooling zone and into direct contact therein with a fluid distilling medium and thereby transforming the latter into a heated gasiform distilling medium, passing the latter in indirect heat exchange with another portion of said combustion gases to superheat said heated distilling medium, and introducing thus superheated gasiform distilling medium to said distillation zone.

9. The process of claim 8 further characterized in that fluid distillation products are removed from said distillation zone and a hydrocarbon-containing light gas fraction is separated from said distillation products and introduced as said fluid distilling medium in contact with the solid particles in said particle cooling zone.

FREDERICK W. LEFFER.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 1,524,784 Bartolomeis Feb. 3, 1925 1,983,943 Odell Dec. 11, 1934 1,984,380 Odell Dec. 18, 1934 2,327,175 Conn Aug. 17, 1943 (Additional references on following page) 301,975 Great Britain Dec. 13, 1928

Claims (1)

1. A METHOD FOR DISTILLING SOLID HYDROCARBONACEOUS MATERIAL WHICH COMPRISES CONTINUOUSLY PASSING SAID MATERIAL IN FINELY DIVIDED FORM DOWNWARDLY THROUGH A CONFINED DISTILLATION ZONE AND THEREIN CONTACTING SAID MATERIAL WITH AN UPWARDLY FLOWING GASIFORM HEATING MEDIUM SUBSTANTIALLY DEVOID OF FREE OXYGEN, DISCHARGING MIXED FLUID DISTILLATION PRODUCTS AND HEATING MEDIUM FROM THE UPPER PORTION OF SAID DISTILLATION ZONE AND WITHDRAWING A STREAM OF DISTILLED SOLID PARTICLES FROM THE LOWER PORTION THEREOF INTO A VERTICALLY UPWARDLY FLOWING GAS STREAM COMPRISING HOT COMBUSTION GASES, OBTAINED AS HEREINAFTER SET FORTH, PASING THE RESULTANT MIXTURE IN A CONFINED VERTICAL STRAIGHT LINE PATH UPWARDLY TO THE TOP PORTION OF A DOWNWARDLY MOVING BED OF SOLID PARTICLES MAINTAINED IN A CONFINED BURNING ZONE SUPERIMPOSED ABOVE SAID DISTILLATION ZONE, SAID CONFINED STRAIGTH LINE PATH EX TENDING THROUGH AND IN INDIRECT HEAT EXCHANGE WITH SAID MATERIAL IN THE DISTILLATION ZONE AND SAID BED OF SOLID PARTICLES IN BURNING ZONE, INTRODUCING A FREE OXYGEN-CONTAINING GAS STREAM TO THE LOWER PORTION OF SAID BURNING ZONE AND THEREBY BURNING SUBSTANTIALLY THE RESIDUAL CARBONACEOUS CONTENT FROM THE SOLID PARTICLES IN SAID DOWNWARDLY MOVING BED, CONTINUOUSLY REMOVING HOT COMBUSTION GASES FORMED IN THE BURNING STEP FROM THE UPPER PORTION OF SAID BURNING ZONE AND HOT RESIDUAL SOLID PARTICLES FROM THE LOWER PORTION THEREOF AND SUPPLYING A PORTION OF SAID HOT GASES TO SAID STREAM OF DISTILLED SOLID PARTICLES WITHDRAWN FROM THE DISTILLATION ZONE, PASSING A STREAM OF THE HOT RESIDUAL SOLID PARTICLES WITHDRAWN FROM THE BURNING ZONE IN A GENERALLY DOWNWARD DIRECTION SUBSTANTIALLY BY ITS OWN GRAVITY AND AT ITS TEMPERATURE OF DISCHARGE FROM SAID BURNING ZONE INTO A COOLING ZONE AND THEREIN CONTACTING THE SAME WITH WATER SO THAT SAID STREAM OF RESIDUAL PARTICLES IS COOLED AND HIGH TEMPERATURE STEAM IS GENERATED, PASSING STEAM THUS OBTAINED INTO INDIRECT HEAT EXCHANGE WITH A SECOND PORTION OF THE HOT COMBUSTION GASES REMOVED FROM THE BURNING ZONE AND THEREBY SUPERHEATING THE STEAM TO A TEMPERATURE SUBSTANTIALLY ABOVE THAT PREVAILING IN THE DISTILLATION ZONE, AND INTRODUCING A STREAM OF THE THUS SUPERHEATED STEAM AS SAID GASIFORM HEATING MEDIUM TO THE LOWER PORTION OF SAID DISTILLATION ZONE.

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