US2595365A

US2595365A - Carbonization of carbonizable solids

Info

Publication number: US2595365A
Application number: US754623A
Authority: US
Inventors: William W Odell; George L Matheson
Original assignee: Standard Oil Development Co
Current assignee: Standard Oil Development Co
Priority date: 1947-06-14
Filing date: 1947-06-14
Publication date: 1952-05-06
Anticipated expiration: 1969-05-06

Description

Patented May 6, 1952 UNITED STATES PATENT OFFICE CARBON IZABLE S William W. Odell, Washington, 1 0., and George .L.:Matheson, Union, N. J., assignors'to Stand- ,ard Oil Development. Company, a corporation of Delaware Application June 14, 1947, Serial -No. 7 5 fl';62 3

:Qiaims. (Cl. L292.6)

This invention relates tos-the.carbonizationof solid fuels. It has to do withzthe carbonization of solidcarhonizable materials :by subjecting them to an elevated "temperature while in a fine state of subdivision. More specifically it relates ,to the :carbonization of finely divided solid fuels and the production therefromof finelymdivided carbonized solids :by. passi'ng the said finely :di-

vided fuelas alstream while lconfinedwin :a ncarbonizer downwardly through .a :hot zone .ata controlled raterwhile promoting combustion in said zoneincontact with said solidsandwhile passing a gasiform :stream upwardly sthrough said downwardly :fiowing fuel lsolids :.at. -suc h .a

. velocity that therparticlesvof. solidfuel in process are maintained as a fluidized state in said rear bonizer. The invention relates to both. process and apparatus vvherebytthe finely dividedsolid iuel prepared foiflcarbonization is .in part doashed prior-to its passage through the hot zone.

- In ordinary practice in carbonizing solid. fuels, the employment of very finely divided fuels-:is avoided-usually because a stationary bed of .such solids iorms a heat.insulatingsmass.rvhichresults in prolonged duration of the-timelofucare ,boniz'ing. So-tar ets -we are aware :it has inot been economical .to treat finely divided solids "for the purpose of making,..a;finely' divided .carbonizedfsolid residue. vOur:experiments-show that a solid fuelcan be economically-carbonized:irna

fine state aof subdivision. provided :meansare supplied for fluidizing it landv:,passing-;ait LiIlFJthB fluidized :state in countercurrent: direction and in.contactwithmpwardly flowing :hotgases. :It

has also been i'ounddesirableto control the temperature'dn :therhot zonelof the fluidized fuel in :the; processand :to. :;control its rate =of=trave1 through theshotszone, vasawell-as :to .control,:ithe nature' of the hottgaseswwith =which ittiscontacted during processing.

..One 'Ejo'f. the, objects; of. this ;inyention is, to carbonize fine1y:;divided. solid, carbonizableziuels rapidly. Another object isto :control the dura- :tion .of. :the .zcarbonizing time, the temperature oiparbonization;xandathenature;ofcthmfiuidizing .gas, :streams .1emp1oyed sci-that.athexxproductuof .car'bonizationzis :hig'hly. weactive; and-:may: :be

nailed van activated .carbon. Another objectuis ;to recover gaseous. :and .yaporous:pmductsirom ;-the carbonization ;o,f {finely divided: tsolid :fiuel. still another-object vis ;.the::-reduction;of-, theash content ,of the :fuel; prior :toits :carbonization.

.Anothermbiect 15.2120 provide apparatus. inawhich the. aforementioned .obiects icansbe. accomplished economically. ".sstill other :obj ects. will; ;become .2 apparent from the disclosures hereinafter made. In the ,,carbonization of goal, it necessary :to take into consideration the condition ofthe coal other than: its state of ,fineness. Thecoal rank and amount of exposure of the coal to the atmosphere have much to do with coking properties of coal. Considerations.- are given to these factors in the operation of the process of this invention. It is well known that lignite. sub-bituminous coal, and certain bituminous c0als'do-no t have strong coking properties and. therefore, they can be readily carbonized in a fine state of division without appreciable agglomeration or building up of large size pieces by cementation. However when coals having, strong coking properties are ground to. fine sizes and are directly carbonized by exposure to heat, the coal passes through a plastic state .at a temperature of aDDroximatelyBOU .toiifii)? F, andv it is-necessary in order to obtain an end product, which is also in a line state of sub-division, to-prevent thev a glomerationof particles or to reduceuagglomerating action to. a minimum. We find that this can bestbe done when the par.- ticles .of coal in process are maintainedin the fluidized, condition during the heating period and particularly during. that period in which they pass through the plastic rangeoftemperature; By maintaining particles during carbonization in vibrant or ebullient. motion, itais found ,that .carbonizat-ion can .be so conducted thata-the solid residue isin a nnestate of s}1h..- division. Qur tests:also-.revealthatitis desir ble to i a n th a cl s o solid. fuel in yiolent state of ebullient :mot n inthe presence 0 =s milars lid$ whichnha e ready. een pe boniZfid, .zyvhile they pass through the plastic range of vtemperature. -When carbonization has once, taken place at. the chosen-temperature, say f ex WW @292 E ac ivati n-1:15 pr m e y as n s eamtth ouehct flu d i d bon d m ssusacti a ing andcqolin simultaneously. Means ior accon plishinga-these ends are vprovided in this invention .as will be- .come evident by reference, to the; .iigure.

The single figure .in the-,acompanyingjdrawing is a diagrammatic ,elevationjof Zone ior.m. of apparatus which can be i used ;in,the carbonization In the; figure the carbonizer i confines abed of fluidized solids having. a :top level L and it has packed zones 2 and 3, which zones containnon fluidized solids .of much-larger =siz than -the;par

ticles of fuel to be treated and which solids form a porous bed or mat, the interstices of which are channels for the passage of the finely divided particles of fuel downwardly therethrough and for the upward passage of gases therethrough. The carbonizer has a porous support l for the bed of fluidized solids, an outlet 5 with control valve 6 for the discharge of the fluidizing stream, and a dust separator 1.

Located adjacent to the top of the carbonizer I and connected thereto is a de-ashing unit I8. This unit is preferably identical in construction and mode of operation with that described in our co-pending application Serial No. 726,530, filed February 5, 1947, now abandoned and entitled Process and Apparatus for Separating Mixed Materials." A similar system is described and claimed for the production of activated carbon in our copending application Serial No. 754,624, filed June 14, 1947, and entitled Processing Carbonaceous Solids. For the purpose of this description it is sufficient to note that near its lower end, the de-ashing unit is provided with a porous grid or grate II below which is an inlet line controlled by valve 24 for introducing a fluidized gas which may be air or combustion gas or any othergas which is preferably not reactive with the solid material treated in this zone. The de-ashing unit is operated so as to maintain therein a level of fluidized solid LI, which is sufficiently high to cause the solid to overflow into the drawofl line 28 controlled by valve 29. This drawoff line terminates in the carbonizer I below the level L of the fluidized solid therein.

At the upper end, the de-ashing unit is provided with a line I2 for leading off the fluidizing gas. The flow of this line is controlled by a valve I3. Connected with line I2 is branch line I5 which may be used to conduct the fluidizing gas, where it is air, oxygen or other combustion supporting gas, to bustle pipe I6 which is connected to the carbonizer I between zones 2 and 3. The flow of gas in branch line I5 is controlled by valve I4. At an intermediate point the de-ashing unit is provided with inlet line 34 controlled by valve 33 through which the finely divided solid fuel to be treated is introduced into the unit. At its lower end, above the grid II the unit has a drawofi line 26 controlled by valve 21 for withdrawing ash from the unit.

' When reference is made to ash in connection with this de-ashing unit, there is contemplated those non-fuel materials with which the fuel matter is contaminated such as quartz, sand, shale, gypsum, pyrites and other mineral matter. This ash has a density greater than the fuel material whereby when the de-ashing unit is operated in'accordance with the teachings of our aforesaid'application, a fairly complete separation of the fuel constituents from the ash can be "realized with the fuel constituents leaving the unit near the top thereof and the ash leaving the unit from its bottom portion. 1

- Combustion supportinggas, which may be air, is supplied through conduit I8 and valve l9 to the combustion zone I! of the carbonizer, whereas said combustion supporting gas is supplied when desired also through conduit 20, valve 2I and inlet 23 to the base of the carbonizer. Steam is'introduced through valve 22 and intake 23. Means for withdrawing the treated solids, namely the carbonized finely divided solids, from the carbonizer, are indicated by offtake 3| and valve 32. Auxiliary means of supplying a gasiform stream to the carbonizer at an upper zone thereof is shown by conduit 9 and valve 8; the stream may be a combustion supporting fluid, steam, gas such as recycle gas, mixtures thereof, or other gaseous material, according to effect desired.

Referring to the figure, the operation, in general, is as follows: Finely divided solid fuel to be treated is charged into a middle portion of the re-ashing unit I0 through valve 33 and conduit 34 at a rate adapted to maintain the bed level LI in saidv unit. Air or other fluidizing gas is introduced through 24 and passes through porous member II, fluidizing the finely divided fuel in III, the gas stream passing out through I2, at least a portion of it being conducted through valve I4 and conduit I5 to carbonizer I, whereas the remainder, if any, is discharged through valve I3. The fuel thus fluidized in I0 separates from a portion of its ash content, the ash passing out through ofitake 26 and valve 21, whereas the de-ashed fuel is discharged substantially continuously through offtake 28 and valve 29 to the carbonizer I.

Steam is introduced into carbonizer I through valve 22 and conduit 23, and combustionis pro-. moted in the hot zone I1, after some of the fuel in this zone is ignited, by virtue of combustion supporting gas supplied through bustle pipe I6 to said hot zone. Valve 32 is opened sufficiently to. allow treated solids to pass out of carbonizer I through offtake 3| at a predetermined rate. The products of the combustion promoted in hot zone I'I, along with the gases resulting from passing steam up through the fluidized solids in the portion of the carbonizer below the hot zone, pass upwardly-through the packed zone 2 and the upper fluidized zone A at such a rate that the particles of said fuel are maintained in vibrant or ebullient motion throughout the bed. Some of the heat generated by the combustion in zone I! is imparted to the downwardly moving fluidized solid fuel of which the bed is comprised.

After operations are underway, it will be found that the steam entering through intake 23 absorbs heat from the solid fuel in the lower portion of the fluidized solids in carbonizer I and to some extent in cooling the carbonized product it reacts therewith forming hydrogen and carbon oxides, which gases further react in the combustion zone I1. Thus the finely divided solid fuel is heated to a temperature above the plastic range in the upper portion of the bed in carbonizer I and it then passes through a hotter zone in contact with the non-fluidized solids 2 and finally through the hottest zone I! of the bed wherein it reaches the chosen maximum temperature and then passes through packed zone 3 and zone C which are the steaming and activating zones, discharging as described through 3i and 32.

Thermocouples indicated by 38 and 39 are employed to aid in regulation of the operation. Sufficient combustion is promoted in combustion zone I! so that the gas stream passing up through the packed zone 2 and through the upper fluidized portion of the bed in zone A, has a temperature sufiiciently high to heat the fluidized particles in zone A to a temperature above the plastic limit so that clogging will not occur as these particles are drawn downwardly into the packed zone 2. Since it is usually desirable to maintain a given maximum temperature in the combustion zone Il, it is sometimes desirable to recirculate products of combustion or other diluent gasiformstream with the air supplied to carbonizer I through lfi inorder to prevent-en cessively -'high "temperature in'zone IT and in order to furnish a-suflicient volume of hot-gas to accomplish the-desired fiuidizingand heating eiiect in zone A.

Inma-king-active carbon, it isusually desirable thatthe particles of the carbonizable material treatedbe heated suddenly to a temperature of the order -of 900 to about 1 200 F., and thatthe product resulting from this heating-be subsequently heated to a higher 'temperatureand subsequently-steamed All of these are acccmplished-in the :operation of the carbonizer l of the=iigure=as described. The hot particlespassing fromzone llrdownwardly through thepacked zone 3,-contact steam rising through zones land 3 and form a given .amount of water gas, which gasris burned in zone -I 7. Thus. a iportionof :the heat required forconducting .the'process is furnished iby -theu'steaming whichis: essential making activatedcarbon. .The operation, with modifications .to suit special conditions, is 'applicable to theproduction of bone black. from crushed bones, to thev production of. a .carbonized fuel suitableior :use, in .makingbriquettes or in mixtunes with coking coal for coke-oven use and .for otherwisettreating materials whichrequire heating to .elevated temperatures and cooling.

example of :the production of. activated. carbon with yieldsobtained in asparticular caseare given :as .follows: Raw, lignite. is .usedas the raw material and-it is: crushed .to. a .size of .20. mesh with .tsomersmaller. sizes. .11. is .then passed through ;an ash separator .as shown at 18 .in .the figure, sand the ash. content. is reduced. During this .-.de-xashing.t.the lignite. is dried by passing .hot gases .upi throughrthede-ashing .unit. The warm partlyJde-ashed lignite in a finestateof division is substantially.continuously discharged from the unit I through ofitake 28 and valve 29 to :the.

carbonizer I into theifluidized bed of similar but hot partly carbonized iignite, which bed is at a temperature 01 .1200 F. This temperature is maintainedintheupper zone. A. Meanwhile the volatile: matter/and tarry vapors are discharged from above thehedthroughseparator l, offtake am! .valve 6. .gThe tarry vapors are condensed andz-separated-by known .means.

The solid particles of .lignite are carbonized in the fluidized state. and. are substantially continuouslyxpasseddownwardly from the :top zone :of thefbed'tto.isubstantially the bottom zone of the bed, inamely; from .zone A :to zone C. Combustionsismromoted in ;a:.middle zone ll. of the .car-

bonizer; :whereby'tthe. temperature is "maintained therein at;.J.-4'Z0;to.:1650 F... Thecombustion is promotedxin: zone I l 1 by passing .the air :used for .fluidizingzzthe solids in .de-zashing unit it? back through valve I4, conduit I5 and .bustle pipe it into thecarbonizer l. Throughout this operationsteam is introduced from beneath grid 4 through cvalve 22 and inlet 23. The solids resultingrirom.carbonization, which under these conditions is an-active carbon, is withdrawn substantially continuously through 'offtake 3i and valve :32.

The-temperature inthe upper "zone A of the fluidized bed in the carbonizer l preferably should be in therange 1000 to 1250 F. for the production Iof-carbon'for'use in removing sulfur froin'gases for example. The amount of combustion promoted in zone 11 is that which will prouidethe desired temperature in the upper zone hand at the same time raise the temperawture'of'tlieparticlespassing through. I 1 tea tem perature oi the order-10f "1450 "to 1'850' 'iE.xusua1iy.

The steampassingxthrough 22' and ..2:3 partly.

coolsthe 'carbon'in zones 3 *andJC, andsimnltaneously generates gas by. the. .waterigas reaction. The gas stream introduced into-lthe:car-

bonizer through pipe i6 is thexmajor 'fluidizingstream component, whereas in 1 the lower portion of the bed, namelyinzones 3 and .C. thesteamsisthe major fluidizing reactant.v :For the purpose of fine adjustment of temperature. someair can.

at will be introduced along withthe. steam. by opening valve 2| to e. desired extent Likewise other'fluidizing medium than the circulating .gas

can be introduced through 16. by :openingravalve l9.

The "raw l-ignite treated as above has-a :composition substantially asrfollows:

" f Percent by weight B. t. u. per pound i 7310 The composition after (drying. and .de-ashing;

The ash removed perton of raw coal 'used was 88 pounds or 52.3 per cent of. the ash originally present. The partly carbonized lignite as it leaves zone A and passes into the packed portion, zone 2, is largely carbon with 5 to 7 per cent of volatile matter, the remainder being ash. The yield at this point is a little more than'35 per cent of the total raw lignite treated. The calorific value is about 12,600 B. t. u. per pound. The tar evolved amounts to "about 5.6gallons 'per ton of raw coal treated. The specificgravity of the tar is about 0.98. The approximate gas yield perton of raw lignite'treated atthis parf ticular temperature, and separately determined, without dilution with other gases, is about 4470 cubic feet.- The 'yield of activated-carbon after passing through zones Band Cis approximately 29 per cent of the original ligniteused.

The-properties-qf carbon-made inthisima-nner vary according-to" the nature of the raw material initially cha-rged to the "rate of 'heating of the upperzone A, 'to'the final temperature attained in the hot/zone l1, and to-the --amount of steaming, as wellasithe temperature of the steam introduced through valve 22 and intake -23. These variables can beadjusted-to suit-anypar ticular case.

It is essentialthat the particles 'of :lignite-in' process be sufficiently fluidized so-that they-=will mix and will fiow downwardly through the packed zones as described. The factors relatingtovelom 'ity'of' flow for given size particlesis now-well known in the art but for the purpose of 'OIELI' -f ness'it may be stated thatwith particles having sizes as given in the foregoing example,-the

velocity of the fluidizing stream-as it leaves the,

bed of fluidized solids in carbonizer l should' be approximately 0.4 to 1.0 feet per second; finer size solids do not require as high a velocity-of the *fluidizing stream as large s'ize particles.

it is important that the size of the packing in zones .2 and 3 be sufficiently large so that the interstices are large enough for the particles of solids being treated to be fluidized therein and flow downwardly therethrough.

It will be understood that the temperature in zone I! may be controlled to suit conditions and may be as high as 2200 F., although it is commonly within a range of 1400 to 1800" F. It is also understood that the steam may be superheated as the occasion requires.

It is further understood that the gases removed through ofitake 5 and valve 6 from the carbonizer may .be used, after removing condensible matter therefrom, as fuel, and supplied to zone l I by means .not shown, or through conduit l8 and valve l9 when so-desired. Similarly the latter gas or gas passing out through valve [3 may also be introduced with the steam beneath grid 4 when desired.

When using strongly coking coals as the raw material to be carbonized, it has been found that the introduction of an auxiliary heating fluid in zone A of the bed above the packed zone 2 is sometimes beneficial. This not only has the effect of decreasing the bed density in zone'A but it permits the introduction of some oxygen, which may be in the form of air, with or without steam or recirculated gas; its use facilitates the heating of the particles in zone A and minimizes any tendency for particle agglomeration, although it does tend to reduce the amount of readily recoverable tar produced. When it is desirable to increase capacity to the maximum, air can be thus introduced through valve 8 and conduit 9, or air with recirculated hot gas may be used with steam as desired.

. Other modifications of operating procedurev may be conceived within the scope of this invention and likewise novel effects may be produced by a different arrangement of packing zones than those shown in the figure. A greater number of packed zones than two may be employed and the packing material used may be spheres, Berl saddles, or other shaped material which will resist exposure to heat and which will furnish satisfactory interstitial space for the flow of particles in process therethrough. The dura tion of the time of exposure of the carbonized particles in zones (land C to the action of steam is controllable by controlling the size of they chamber confining these zones, particularly the depth.

Referring to the figure, operating adjustments are made, after the rates of flowof feed-of fresh solids, discharge of treated solids and supply of fiuidizing medium are once set, as follows: To increase the completeness ofcarbonization of the solids flowing into zone B from zone 2 either decrease the rate of feed of solids by adjusting valve 29 and similarly adjusting valve 32, or increase the circulation of gases to the combustion zone by more completely closing valve i3 and opening valve 16 more fully, or by introducing an additional amount of combustion supporting gas by opening valve I9, or by combinations of these adjustments, or by heating the raw fuel in it) to a higher temperature bypromoting combustion reactions therein using more oxygen introduced through 24. Another adjustment for accomplishing a similar result is to supply a combustion supporting gas by opening valve 8. To decrease the completeness of carbonization of the solids at about the bottom of zone 2 the opposite adjustments are made. 1

In case the temperature of the solids being and the flow of solids in process regulated ac-- cording thereto or the flow of fluids, particularly the combustion supporting fluids should be adjusted in accordance therewith. I

For fiuidizing solids varying from very finesize in one case to very coarse in another case, the velocity of the fiuidizing gas stream measured as in an empty carbonizer will vary respectively from about 0.1 to 10.0 feet per second. The velocity referred to at this point, and at other points in the specification, is superficial velocity; that is, the velocity which would obtain in the enlarged zone or reactor with a given inlet and outlet velocity if the enlarged zone or reactor were empty. When operating at low carbonizer capacity it is sometimes necessary to use an appreciable amount of recirculated gas and only a small amount of combustion supporting gas. In this case gas passing out of the carbonizer through 5 and 6 is recirculated back to the carbonizer preferably after removing condensable product; it is compressed to the necessary pressure and is supplied through valve 31. Actually very little heat is required, when the fuel is sup-,-

plied dry, in addition to that carried away as.

sensible heat in the gas and solids, and it is pose-r sible to reduce these losses to small quantities. For example when zones C and 3 are deep, the solids may be discharged cool and steam at about 250 F. may be used. This effect is further facilitated by employing a deep zone C and incorporating another packed zone in it but spaced below zone 3.

Normally the pressure in the system is just sufficiently above atmospheric pressure to operate as described but with some carbonaceous solids the physical nature, porosity, density, etc. are appreciably affected by a change in pressure; hence this invention is not limited in this respect it may be operated at high or low pressures. The density of the product made at high pressure is greater than that made at low pressures.

Referring again to the figure, the zones Cand 3 are shown to have smaller diameter than A and B but this is not always necessary. The diameter is proportioned so that the velocity of the stream flow will fiuidize the solids in zones C and 3. Because the volume of gaseous fluids flowing upwardly is greater in zones A and B than that in C and 3 it is advisable that the latter zones be of smaller diameter than the former zones, in order to obtain best results.

The actual time required to carbonize a fuel when the particles are say 60 to 200 mesh size is a variable depending on the moisture content of the fuel, volatile matter initially present therein and its temperature as charged as well as the velocity of flow and temperature of the gases passing upwardly through the bed. With a temperature of 1200 F. in zone A coal can be carbonized in zones A and 2 in a matter of seconds, 10 to 30 seconds being usually ample. However, operating variables may be adjusted to provide longer or shorter time when desired. A conven ient rate of supply of dry coal to carbonizer l for carbonizing is 0.05 to 0.25 pounds per second per square foot of horizontal sectional area of zone A, varying with the depth of zone A and the temperature of the gas stream rising from zone 2 into zone A and the velocity of said stream. The overall duration of the carbonizing time (total time in the carbonizer) may be adjusted at will. Normally a convenient time is of the order of 20 to 60 seconds.

It will of course be understood that the carbonizer can be operated without the de-ashing unit when desired. In this event either chamber l0 can be considered as a reservoir or the feed for the fuel carbonizer can come directly from conduit 34 and through valve 33. In this case consider valve I4 closed and the gases for zone I! are supplied through valves l9 and 31.

One skilled in the art will recognize that the procedures outlined herein and modifications of them will be applicable in making low-temperature coke, high-temperature coke, in the pyrolysis of oil shale, and in general in heat-treating finely divided solids particularly carbonaceous solids. Magnesium carbonate gives up CO2 at 350 C. and calcium carbonate decomposes at 825 0.; these products may be calcined, in a fine state of division in this manner. In this case air would be used as the bottom fiuidizing agent and coolant and it would be preheated in traveling up through zones C and 3 and would be the combustion supporting fiuid in zone 11, the fuel could be introduced through valve 31.

Having described our invention so that one skilled in the art can practice it, either as described or with modifications, we claim:

1. The continuous process of carbonizing carbonizable solids which comprises forming a deep single substantially continuous downwardly moving bed of finely divided carbonized solid fuel in an upright carbonizer, continuously feeding the carbonizable solid in finely divided state to the upper part of said bed, maintaining said bed in a fluidized, condition by passing upwardly therethrough a stream of gas comprising, near the lower part of said bed, steam introduced at that point and, at a higher level in said bed, steam, combustion supporting gas and gaseous combustion residues, causing said bed in its downward travel to pass through the interstices of large size bodies maintained as a pack in two separate zones in the path of said bed, said packs preventing back-mixing of the finely divided solid upwardly through said zones into preceding portions of saidbed..introducing the combustion supporting gas into said bed between said zones, recovering from above said bed vaporous products of the carbonization of said carbonizable solid and recovering carbonized solid from the lower por-- tion of said bed below the point of introduction of steam into said bed, the flow of materials and the feed of steam and combustion supporting gases being so regulated that throughout the upper portion of the bed above the upper packed zone, the finely divided material is maintained at a carbonization temperature above the plastic range of said carbonizable solid and between 900-1400 E, in the next lower zone including the upper packed zone, the finely divided material is maintained at a temperature between about 1600-2000 F., and in the lowermost zone, including the lower packed zone, said material is quenched with steam.

2. In the process defined in claim 1, the step of introducing a small amount of a combustion supporting gas along with the steam.

3. The process as defined in claim 1, in which the solids are fuel selected from the class consisting of lignite, sub-bituminous coal, bituminous coal, semi-bituminous coal, and anthracite coal.

4. A method according to claim 1 in which the finely divided carbonizable solid fed to the carbonizing zone is subjected to a preliminary treatment for the removal therefrom of ash constituents.

5. A method according to claim 1 in which the combustion in said next lower zone is at least in part the combustion of combustible gases produced by the reaction between steam and hot carbon in the quenching zone.

WILLIAM W. ODELL., GEORGE L. MATHESON.

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

UNITED STATES PATENTS Number Name Date 1,639,356 Wallace Aug. 16, 1927 1,923,918 Davis Aug. 22, 1933 1,927,459 Krczil Sept. 19, 1933 1,955,025 Salbel et al Apr. 17, 1934 2,148,827 McFarland Feb. 28, 1939 2,162,763 Stuart June 20, 1939 2,444,990 Hemminger July 13, 1948 OTHER REFERENCES Bureau of Mines R. 1., 3,711, May, 1943. l

Claims

1. THE CONTINUOUS PROCESS OF CARBONIZING CARBONIZABLE SOLIDS WHICH COMPRISES FORMING A DEEP SINGLE SUBSTANTIALLY CONTINUOUS DOWNWARDLY MOVING BED OF FINELY DIVIDED CARBONIZED SOLID FUEL IN AN UPRIGHT CARBONIZER, CONTINUOUSLY FEEDING THE CARBONIZABLE SOLID IN FINELY DIVIDED STATE TO THE UPPER PART OF SAID BED, MAINTAINING SAID BED IN A FLUIDIZED CONDITION BY PASSING UPWARDLY THERETHROUGH A STREAM OF GAS COMPRISING, NEAR THE LOWER PART OF SAID BED, STEAM INTRODUCED AT THAT POINT AND, AT A HIGHER LEVEL IN SAID BED, STEAM, COMBUSTION SUPPORTING GAS AND GASEOUS COMBUSTION RESIDUES, CAUSING SAID BED IN ITS DOWNWARD TRAVEL TO PASS THROUGH THE INTERSTICES OF LARGE SIZE BODIES MAINTAINED AS A PACK IN TWO SEPARATE ZONES IN THE PATH OF SAID BED, SAID PACKS PREVENTING BACK-MIXING OF THE FINELY DIVIDED SOLID UPARDLY THROUGH SAID ZONES INTO PRECEDING PORTIONS OF SAID BED, INTRODUCING THE COMBUSTION SUPPORTING GAS INTO SAID BED BETWEEN SAID ZONES, RECOVERING FROM ABOVE SAID BED VAPOROUS PRODUCTS OF THE CARBONIZATION OF SAID CARBONIZABLE SOLID AND RECOVERING CARBONIZED SOLID FROM THE LOWER PORTION OF SAID BED BELOW THE POINT OF INTRODUCTION OF STEAM INTO SAID BED, THE FLOW OF MATERIALS AND THE FEED OF STEAM AND COMBUSTION SUPPORTING GASES BEING SO REGULATED THAT THROUGHOUT THE UPPER PORTION OF THE BED ABOVE THE UPPER PACKED ZONE, THE FINELY DIVIDED MATERIAL IS MAINTAINED AT A CARBONIZAION TEMPERATURE ABOVE THE PLASTIC RANGE OF SAID CARBONIZABLE SOLID AND BETWEEN 900-1400* F., IN THE NEXT LOWER ZONE INCLUDING THE UPPER PACKED ZONE, THE FINELY DIVIDED MATERIAL IS MAINTAINED AT A TEMPERATURE BETWEEN ABOUT 1600-2000* F., AND IN THE LOWERMOST ZONE, INCLUDING THE LOWER PACKED ZONE, SAID MATERIAL IS QUENCHED WITH STEAM.