US1841626A - Retort furnace - Google Patents

Description

A- MUSSO RETORT FURNACE Jan. 19, 1932.

W INVEN Filed March 20, 1929 uwmm i N. m3 @N g Q TN 3 mm 5 mm #3 ATTORNEY-5 Jan. 19, 1932. A. Musso RETORT FURNACE Filed March 20, 1929 3 Sheets-Sheet 2 INVENTOR 9' ATTORNEY A. MUSSO RETORT FURNACE Jan. 19, 1932.

Filed March 20, 1929 3 Sheets-Sheet 3 INVENTOR Y ATTORN EYS Patented Jan. 19, 1932 UNITED STATES PATENT OFFICE ALFRED MUSSO, OF EAST ORANGE, NEW JERSEY, ASSIGNOR 0F ONE-HALF TO WILLIAM P. DEPPE, OF NEW YORK, N. Y.

RETOR'I FURNACE Application filed March 20, 1929. Serial No. 348,379.

, This invention relates to furnaces and proc esses practised in connection therewith.

One object of the invention is to provide a device of the character described, including improved means for heating a chamber from the outside thereof.

Another object of the invention is to provide an improved device of the class specified including an eXterio-rly heated chamber, the charge in which, at any point of the chamber, is subject to heating by conduction and radiation at substantially the same temperature, although the difi'erent points of the chamber may be at the same .or at different temperatures as predetermined.

Another object of the invention is the provision of a device of the nature set forth hav ing improved means for movement through a furnace or retort chamber of the charge that is being heat treated therein.

Another object of the invention is to furnish a device of the type mentioned having a heating chamber which is divided into a plurality of compartments by improved means that restricts the flow of gases from one to another of the compartments and coacts for movement of the charge in the chamber through the successive compartments.

Another "object of the invention is to construct a device of the species alluded to, having a heating chamber through which is passed the charge that is being treated, which device includes improved means for separately removing from the chamber the gases in diflerent sections thereof. 1

Still another object of the invention is to provide a device of the character described having improved means to create a partial vacuum in a retort and to exhaust all gases generated inthe retort chamber in stages ac-.

cording to predetermined temperature or temperatures.

Still a further object of the invention is the provision of a heating device operating un der a co-ordinated temperature and pressure gradients, and an improved control to automatically maintain the requisitetemperatore-pressure relationship.

Other objects of the invention are the pro vision of an improved device of the nature set forth wherein a temperature gradient is maintained in an improved manner in the heating chamber; and wherein heat is imparted' to the chamber without causing oxidation of the same; and wherein the gases generated are removed'in one or more stages from the heating chamber without removal of the nongaseous ingredients that are being treated regardless of how fine the same may be; and wherein an. improved device controls and mixes the supply of air and gas.

Still further objects of the invention are to provide an improved process for heat treat ing a charge by conduction and radiation at opposite sides but at predetermined temperatures without contact with the products of combustion; also to provide an improved system of heating the charge by radiation under reduced pressure or partial vacuum.

Still further objects of the invention are the provision of an improved process for the heat treatment of materials, wherein the factors of temperature, pressure, and reaction velocity are co-ordinated for equilibrium conditions; and an improved apparatus for carrying out this process. v

This invention is particularly intended for use in my process of low temperature reduction of metals, Serial No. 325,713, filed December 13th, 1928, and aims to provide an eflicient apparatus therefor.

It must be kept clearly in mind by those skilled in the art, that since the process, more specifically disclosed in copending process application, Serial No. 325,713, filed December 13th, 1928, to which this apparatus is primarily directed includes a co-ordination of temperatures, pressures, and particular retort atmospheric conditions conducive to the chemical reactions involved, under the limitations and physical forces necessary for the effective practice of the process, that the combinations of the structural features of the apparatus in their physical and functional relationshipsmust also be co-ordinated in a corresponding sense; hence the apparatus illustrated involves some unusual interrelations which have never been heretofore devised.

It must be particularly noted that the apparatus suitable for this new process, illustrated in this disclosure employs for the first time, the principle of reducing iron ores with any kinds of coal in mass production conditions, in an air-tight retort, wherein is included the means for mechanically accelerating the substantially complete reduction of the materials being treated by means of solid carbon reduction. The gaseous reactions are substantially eliminated, through the continuous forcible exhaustion of all gases being liberated and formed in the process, at temperatures below the fusion points of material which eliminates melting, agglomeration, or sintering. The volatile constituents of coal and the maximum amount of CO available, continuously and forcibly withdrawn from the reducing ambient in this process, causes the novel result of the production of suflicient fuel gases to operate the system.

In this process, which is primarily devised for mass production conditions, particularly for the use of any kinds of iron ores, oxides, or carbonates, and any kinds of coal, in order to decrease the time for substantially complete reduction of the ores being treated, particularly iron ores, at lowered temperatures, it is essential to forcibly and continuously exhaust all gases in the retort as fast as formed, to practically eliminate the gaseous reaction conditions, and to maintain substantially solid carbon reaction, with chiefly CO produced, and little or no CO produced, and with lower temperatures permissible in the retort, but high enough to cause substantially complete reduction, and

- yet not high enough to cause fusion, thus eliminating melting, agglomeration, or sintering in the materials being treated. For example, the maximum temperature for reducing iron ores mixed with coal, is approximately 950 C.

Other objects and advantages of the invention will become apparent as the specification proceeds.

With the aforesaid objects in view, the invention consists in the novel combinations and arrangements of parts hereinafter described in their preferred embodiments, pointed out in the subjoined claims, and illustrated on the annexed drawings, wherein like parts are designated by the same reference characters throughout the several views.

In the drawings, which are submitted to show features of the invention, but not to limit the scope of the claims:

Figure 1 is a longitudinal view in vertical section of a device embodying the invention.

Fig. 2 is a cross sectional view takenon the line 2-2 of Fig. 1.

Fig. 3 is a similar view taken on line 33 of Fig. 1.

Fig. l is an enlarged fragmentary view of the exhaust pipes and a strainer, shown in Fig. 1.

Fig. 5 is a view in section taken on line 5-5 of Fig. 4.

Fig. 6 is a vertlcal sectional view taken on line 66 of Fig. 1.

Fig. 7 is a view in elevation of a heating means for a retort with parts in section.

Figs. 8 and 9 are sectional views taken on horizontal and vertical lines, respectively, on Fig. 7.

Fig. 10 is a view in section of the fuel control and mixing apparatus.

Fig. 11 is a cross sectional view thereof taken on line 1111 of Fig. 10.

Fig. 12 is a diagrammatic view of a coordinated temperature and pressure control.

Fig. 13 is a fragmentary view in vertical section taken on line 13-13 of Fig. 1.

Fig. 14 is a view in vertical section of a modified heating ring and furnace arrangement.

Fig. 15 is a view in vertical section of a. still further modification of a heating ring.

Fig. 16 is a vertical sectional view taken on line 16-16 of Fig. 15.

Fig. 17 is a diagrammatic view of a modified arrangement of the heating rings with respect tothe work or retort furnace.

Figs. 18 and 20 are fragmentary views in longitudinal vertical section of heating chambers with modified partition constructions.

Figs. 19 and 21 are transverse sectional views taken on the lines 1919 and 21 21 of the devices shown in Figs. 18 and 20, respectively.

The advantages of the invention as here outlined are best realized when all of its features and instrumentalities are combined in one and the same structures, but, useful devices may be produced embodying less than the whole.

It will be obvious to those skilled in the art to which this invention appertains, upon becoming conversant with the features thereof, that the same may be incorporated in several different constructions. The accompanying drawings, therefore, are submitted merely as showing the preferred exemplification of the invention. The underlying scientific theory, as well as the objects of the invention will determine its scope, as it is possible to produce other devices which will accomplish substantially the objects of the reaction is a function of the ratio of the pressure to the temperature. By my improved process, this function governs the reaction throughout, so that the reaction velocities are uniformly accelerated or retarded, as the case may be. A reaction whose velocity is a practice this can be but approximated in stages as hereinafter indicated.

As a specific example of the subject matter set forth in the preceding paragraph, I may mention that .in the process of mineral reduction, for instance, in that of ferric oxide J (Fe O bymeans ofthe fixed amorphous carbon of coal, we have two phases, -viz., solid iron (Fe) and gaseous carbon monoxide (CO) coexistent at all times, while the carbon (C) and the oxygen (0) which form the C0 are combining under equilibrium con-- ditions. To better explain the fundamental vtheory, in the case of iron reduction, I will set forth the chemical equation of the reduction, which-is x FBzbg-I-SCQZFB-l-iiCO This equation is to'be considered as the eiiect of the two simultaneous equilibria, viz.

2Fez0z24Fe-k30z (dissociation of ferric oxide) Oz+2C? 2CO (formation of carbon monoxide).

Ofthe two simultaneous equilibria, the first one tends to liberates the iron contained in combination with the'oxygen in the ferric, oxide, while the second equilibrium tends to eliminate the oxygen as such from the system byconverting it to carbonmonoxide. The

completion of the reaction, according to well' established principles of physical chemistry, is brought about by the elimination of the gaseous phase 00 from the system, by the exhaustion of the gases from the retort chamber as fast asthey are generated. In order to further avoid the possibility of a reversible "reaction, an excess of carbon is supplied and always present, conforming thus withthe well known principle of mobile equilibrium and the law of mass action. This brief discussion on the basic principles of my invention as applied to iron reduction, is general and applicable to all kinds of reversible reactions which canbe caused to occur in my apparatus: In all reactions, such as the reduction of iron above referred to, where gas is generated, and where the natural tendency would therefore be toward an increase of the total pressure of the system, any reduction of the total pressure, will favor the reaction.

on the other hand, there is for each pressure a corresponding .definite temperature, and vice versa. Thisjresults in thetheory that in any system contemplated by my inven- Tho'completeness of the 'reac- Q tion, where, during the course of a reaction, temperatures and pressures must be made to vary, in order to attain a completion of the equilibria involved, the course of the reaction is a function of the ratios of the pressure to the temperature. And this is the 'statement of the general process provided by my 'invention.

While for: the reduction of iron ore, the temperature is increasedrand the pressure dc creased, the invention is equally applicable tosuch reactions as require av decrease in temperature and simultaneous 1 increase in pressure; or an increase or decrease of both temperature and pressure; or where1n-one of these factors remains constant while the other alone changes, although 1t is contemplated that the best conditions are obtained by causing both temperature and pressure to harmonize for the reaction: in each case, the

rate of the change of these factors,or the rate of change of the ratio of the factors is sub stantially constant, as, forinstance, according to an arithmetic progression. It is preferred that the temperatures and pressures herein be taken onthe absolute scales, although other scales can also be used.

It is noted that, for certain reactions, successive changes of temperature and pressure may be such that the difl'ereuce'between the ratios is substantially zero.

Referring again to the reduction iron,

the increase-of temperature and decrease of pressure tends to promote the dissociation of the iron oxide. The decrease of pressure, however, mihtates agamst the formation of the carbon monoxide, but th1s'1s counteracted by several factors, among which are the in-,'

crease of temperature, the natural aflinity of oxygen for carbon, and the. presence of hydrogen which acts as a catalyst in the formation of carbon monoxide. In the last stages of.the reduction, hydrogen is evolved in rather considerable quantities from thev carbonaceous fuel which is used in the charge and acts effectively as above stated.

The term charge is intended to denote the ingredients in the'retort at any stage of the reaction, or any materials or articles that maybe advantageously heat treated in a fur-- nace embodying one or more; featuresof this invention, regardless of whether or not such heat treatment is accompanied by a chemical reaction.

Generally described, the inventionprovides an elongated heating chamber, which may be in themature of a cylindrical retort.

The same is rotatable about its axis, 'Wh-lCh is preferably inclined with the horizontal, to cause the charge introduced inthe retort to move therethrough. The end portions of the retort arev each formed with-a concentric series of conveyer pockets which rotates with the retort. Coacting with each series of pockets is a circular stationary closure member so arranged to. permit a lowermost pocket to receive a portion of the charge, but to close the filled pocket as it moves upward, and finally to permit the charge to be removedothrou h an opening in the member with which when the same reaches its uppermost position. The charge in the pockets thus acts as a seal and contributes to render the retort air tight. This system of conveyer pockets feeds the charge tobe treated int-o theretort at the upper end of theretort and feeds said charge from the retort after treatment at the lower end of the same. Dividing the retort into a plurality of successive compartments are transverse partitions which are of substantially gas tight construction. These partitions comprise the conveyer features that are provided at the ends of the retort, and thus cause the charge to be passed from one compartment to another. Extending centrally through the retort is a stationary shaft that supports the stationary circular members of the partition conveyer construction. Associated with the shaft are a plurality of pipes communicating individually with'the compartments, whereby the gases in the latter may be exhausted by pumps. A screen may serve to prevent finely divided ingredients in the retort from entering the pipes. A scraping blade or other similar device may keep the strainer clean. The retort is heated by radiation from the outside by means that are disposed between the retort and the wall of the furnace, the intraspace being closed so that air may not leak thereinto. Preferably the said means are in the nature of stationary rings concentric with the rotating retort and disposed therealong in spaced relation to each other; thus transverse sections of the retort are maintained at the same temperature along the peripheral surface of each section, so that the charge lying along the bottom of the retort is uniformly heated from its undersideby conduction and from above by radiation, the latter occurring with high efiiciency due to the exhaustion of the gases from the retort, and the consequent elimination of any gas film that would otherwise adhere to the interior surface ofthc retort wall. The said rings may consist of pieces of refractory material calcined with a suitable binder and having considerable voids to permit passages therethrough of the waste combustion gases, while the outside of each ring is glazed to render the same gas tight. Premixed gas and air in combining ratio are fed under pressure into each ring, and surface combustion occurs therein. To maintain a temperature gradient the spacing of the rings may be varied. An automatic control co-ordinates the temperature and pressure in the retort in the pocket comes into registry,

" For metallic reduction, an apparatus as above described is preferably employed, but for oil shales orsimilar materials, the retort may be maintained at constant temperature throughout the length thereof, and the subdivision of theretort into compartments with separate exhaustion of the same may be eliminated.

While the invention contemplates preferably the application of the same to the re duction of minerals, certain principles thereof are applicable to furnaces of heating chambers of Widely different types where uniform heating is desired, with ,or without the use of a retort, as, for example, in soaking furnaces; and also to different chemical or mechanical operations, as, for instance, roasting or driving off volatile constituents in materials other than mentioned, or treating substances under varying conditions of temperature and presthe heat so obtained may be generated in a central heating chamber and directly passed about the retort or through tubular devices capable of radiating their heat upon'the i'etort. Electrical heating can be employed also, although this may be considered as too expensive for ordinary commercial use, It suffices that a uniform temperature is obtained for the charge that is being treated, both by conduction and radiation, and especially when accompanied by a simultaneous rotation of the retort.

The end walls, or partitions, or both may assume different forms, depending, among other factors, upon the partial vacuum that is desired in the retort, and whether a pressure gradient is maintained in the same, or whether the" gases are exhausted in separate compartments or stages but at substantially the same pressure.

In the treatment of finely divided materials of any kind, as, for example, in the reduction of a mineral by a solid fuel, there is a known interstitial volume V and a known free volume V in the retort, the ratio of the volumes being a number larger than 1. Now, considering at any instant the pressure and temperature, and P being the pressure in the interstices,

and P the pressure in the heating chamber and because I P1 V =mV P =mP -o1' P2=E which may be even less than one atmosphere. In all cases, the value of P is less than if no exhaustion occurred, for then P would equal P that is, the pressure in the free space in the retort would equal the pressure in the interstices. Since is known can be maintained constant, for each condition of temperature in the retort. The electrothermal mechanical device disclosed herein renders it possible to automatically maintain the pressure-temperature ratio. Similarly, because the ratio of the volumes V and V is known or can be predetermined for any required pressure ratio the temperature to correspond to the initial required conditions can be readily obtained. Thus for any 'given conditions, and since the ratio of the volumes V and V is substantially constant throughout the retort, it is always possible to determine the ratio of the pressure P of the retort chamber to the temperature T of the same. From the preceding discussion, the value of the ratio P /T is obviously a function of the initial condition and therefore can be predetermined or modified as one of the two terms of said ratio may vary in the course of the reaction.

The rate at which the ingredients that are being treated undergo the' desired change, and more particularly the reaction velocity, as in reduction of a mineral, is fixed by the pressure-temperature ratio, which thus predetermines the time that is required for the complete reduction of the mineral. Accordingly, the time during which the ingredients are to remain in the retort, and consequently the proper rotational speed of the retort may be ascertained. By thus c o-ordinating temperature, pressure, and reaction yeloc'ity to assure proper equilibria at various points of the reactions, there results continuous performance with completeness of the reactions 'and purity of the metal. With the eliminafurnace, Serial No. 259,406, filed March 6th,

1928. The said device comprises a heating chamber or retort 21, made of any suitable material consistent with the temperature required. For the comparatively low temper atures used in my process, the retort may be made of steel with an inside and outside coating of chromium. For higher temperatures a chrome alloy steel may be found suitable. In general, any metallic alloy adapted to withstand high temperatures is employed, the use of metal permitting a more economical transfer of heat through the wall of the retort and also a lighter construction in the mounting thereof.

The retort 21 may be of cylindrical or other form rotatable about its axis which makes an angle with the horizontal to move the charge therein from the upper inlet end 22 to the loweroutlet end 23 thereof. The retort may also be differently arranged, particularly if a diiferentsystem is employed for moving the charge through the rotor.

The retort is mounted in a furnace 24 having an elongated chamber 25 to receive the same, which chamber is closed by stationary end plates 26, 27. The wall of the furnace may beconstructed of refractory brick or other like material and the end plates may be of metal of a heat resisting nature, properly insulated.

The end portions of the retort are enlarged' in diameter at 28, 29, and the free edges of the same are received in annular recesses in the end plates to form a tight connection. The member. 29 includes an oppositely projecting annular flange 31 that engages in a circular recess 32 in the furnace wall.

. Carried exteriorly by the member 29 is a gear 33, whereby the retort may be rotated at a predetermined speed by any suitable source of power, such as an electric motor. Suitable idlers, in the nature of pinions, whose teeth mesh with those of the gear 33, may serve to support theretort, but this arrangement being readily understood, has not been shown. At the other end of the retort, a circular band or rail 34 takes about the same, and rides on idlers 35 to support the retort. Similar band and idlers are prm vided at the center of the retort. To obtain access to the idlers, heat insulated plugs 35a maybe used.

The circular spaces within the members 28, 29 are divided by radialwalls 35 into a plurality of alined circular series of pockets 37, 38, which constitute conveyers. The radial walls terminate at 39 so as to'extend in the general direction of the lengtli' of the retort and also radially inward so as to terminate at 40 in spaced relation to the axis thereof. At 39, however, the conveyer pockets are closed by the stationary end plates 26, 27 with which the radial bucket partitions 36 have clearance. Closing all except the uppermost and lowermost pockets of the conveyers 37, 38 at their inner edges 40 are circular or substantially cylindrical drums or closure members 41, 42, respectively, the same being fastened to or integral with the end plates and are substantially equal in diameter and coaxial with the retort, but fixed with respect thereto, being mounted upon a stationary shaft 43 that extends centrally through the retort and is secured at 1ts ends in the hubs 44 of the said end plates. Each of the members or drums 41, 42 has a supporting disk portion 45 through which the shaft passes. At its upper part, the member 41 has an opening 46 communicating with a downwardly inclined chute 47 passing through the end plate 26, with the lower wall of the chute extending to the disk 45 to which it may be secured. The lower part of the member 41 has an opening 48 in the wall 45 thereof, there being a top entrance member 49 for said opening extending into proximity or fastened to the end plate 26.

The charge in the retort will tend to load: through the opening 48 into any lowermost pocket of the conveyer 37 and be carried upward with the rotation of the retort, about the circular closure member 41 until the pocket comes into registry with the opening 46 permitting the load therein to be discharged from the pocket into the chute 47 The member 42 at the inlet end of the retort has openings 50, 51 similar to those at 48 and 46, re-

spectively, so that charge may be carried from a hopper 52 down a chute 53 and thence though the opening 51 into any lowermost pocket of the conveyer 38, after which the charge is carried upward in the pocket about the member 42 and finally discharged through the opening 50 down an incline 54 into the retort.

The heating chamber or retort 21, is divided into a series of consecutive compartments 56 to 59 by-a plurality of transverse walls or partitions 55 comprising conveyers according to the principle of the conveyers 37 and 38. Each of the said partitions includes a ring plate 60 secured to the wall of the retort and having a circular series of radially extending blades 61 that have free edges 63 and 64, the former projecting toward the axis of the retort, and the latter toward the inlet end thereof. The said blades provide a circular series of conveyer pockets 55a concentric with the retort. /losing the said conveyer pocket at the edges 63, 64 thereof are circular closure members 65, each of which includes a disk 66 mounted on the stationary shaft 43 and coacting with the edges 64. Each of said disks carries a cylindrical drum 67 having closure coaction with the edges 63. At the upper part of the drum, the same has an opening 68 to register with an adjacent conveyer pocket. Now each disk has an inlet opening 69 disposed to one side of the vertical plane of the retort, according to the counter-clockwise direction of rotation of the same, which will cause the charge in the retort to pile toward the right side thereof. If the retort should move clockwise, the inlet 69 would beat the left side. Thecharge passes through an opening 69 into any lowermost pocket of the conveyer 55a, and as the retort rotates, the charge is carried upward over the closure member or drum 67, until, in the uppermost position of the pocket, the charge moves throu h the opening 68, down an incline '70 into t e next succeeding compartment.

Thus at the inlet and outlet of the retort, and at the partition '55, positive movement of the charge is assured, under conditions that substantially prevent leakage of air, or gas, or both. The finely divided ingredients of the charge serve to seal theclearance) spaces at the conveyers. Within the retort the charge may thus be caused to move at a positive uniform speed through the successive compartments 56 to 59, depending upon the speed of rotation of the retort and the consequent speed of the conveyers.

To obtain further air. tightness of the retort, the chutes 47 and 53 may be each provided with a plurality of spacedfly valves 71, 72 which are geared together in any suitable manner for simultaneous movement.

The valves are set so that when one of them is open, the other is closed, thus avoiding air leakage. The quantity of charge passing through a chute at any operation of the valves is determined by the space between the valves. Since the charge is in finely dividedcondition, practically no air will enter therewith.

Extending along the stationary shaft 43, are a plurality of pipes 73 to 76 Which enter the retort at the inlet side thereof, and each of which communicates with one of the c0mpartments 56 to 59 respectively. The shaft 43 may be grooved longitudinally as at 77 to receive the pipes, thus making for a highly compact construction. At the retort partitions 55, sleeves 78 are provided closely receiving the said pipes and having flanges '79 at the ends. of the sleeves, which may extend to the surface of the said pipes and of the shaft. The drums 65 are securely mounted on the collars, the flanges of which are on opposite sides of the drums.

Externallyof the retort, the pipes communicate individually with exhaust pumps 80 to. 83, that are of any suitable type or size according to the reduction of pressure desired in the retort and in the particular com- J partments thereof. By means of this artort. The wall of the retort is spaced from rangement, a pressure gradient can be mainthese areas any suitable distance consistent tained in the retort, with pressures which with economical heatin under-uniform radimay be considerably below atmospheric,varyation to the retort, an while this space as 'ing from one to another of the successive shown in the drawings, is preferably com- 70 compartments 56 to 59. v paratively close, it may be substantially vin- To preventfinel divided ingredients of creased to meet all operating conditions. the charge in the retort from being drawn Since the radiating zones are of ring form as .into an exhau pip ny Suitable means W 1 above stated, any compartment or transverse known in the art may be employed, whether section of a compartment is subject to uni- 75 electrical or mechanica t0 form temperature all around to impart uniby centrifugal action, or simple screens" 84 f h atin b nd tion and radiation to m y be Used? The e are yl ri al in form the charge in the retort. Since the retort I 110 urround the plp s and extend from is exhausted causing the rapid removal of to end of each compar men They y be inert gases from along the wall of the retort,

Secured to y shitahlemeahs, e for examthe radiation of heat onthe charge is imple the flanges 79, and similar flanges 85 proved 7 adjacent to the end Walls Of the P hu Each zone 90 may include a ring- 91 that is the gases exhausted y the 531d P P are set into the wall of the furnace or extends into thoroughly sel'eehede the large Screen the chamber 25 thereof as shown. The area, there is Practically he cloggihg'of the rings may all be of the same construction,

- SeI'eehS- Furthermore, the .sel'eehs e P being made of a porous mass of refractory Sitiohed remotely from t ch g in which is gas tight along the outside thereof. bottom ht e y, ahvehvleus Thus a refractory-consisting of pieces 92 of manner, be (imposed t hpp tether carborundum, zircon, or graphite may be Pe the retort, and efl y used enclosed in a gas tight refractory wall. Wlth the P p in e eehtml p t reo Preferably, the said pieces have been previ- The eeveralscreensmay be of varymg n ously mixed with a binder, as for'instalice, to Shlt the eempahtmehtsa n P y of -tar, then moulded into ring form, and cal screens y. he d p exterml'ly of each cined at a temperature above that to which other with the Screen of lehgeh mesh the ring will be subjected to volatilize all Side: t desired, a p h yl e e to hydrocarbons of the binder and lea'veastrong automatlcally clean the screens coincident b dy f refratory Th th id with the rotation of the retort. If desired atthe surfaces of the ring can be filled with y Suitable design of h t traps Q tar refractory to provideacomparatively smooth y Scrubbers y be lhehlded m the base. Finally, the outside surfaces of the hhe between the retort and the p p ring are glazed at the base thus formed to P p a plurality of arms 87 extend-from the may be glazed or permitted to remain unform hf Spaced eyhhdhiealhl'eas rings the surfaces 96 communicatingwith the burner uexternally or internally; More specifically, The cement 99 is intended to reenforce the so they provide a means of indirect heating of ring at the region where the maximum temue g h ga he fast as e provide a gas tight surface, but the surface To hl'aee theisheft 43 and the sald'exhahst 93 of the ring that contacts the furnace wall h h t retort and terminate hub 88 glazed and sealed with the furnace wall. 1 whlch the collars 78 Y rotatable r313" The latter is preferably also glazed to render tlohv it impervious to gases. The glazing mateheat the retort 7 lh h of spachd rial is any high temperature siliceous matehh h n l e m the fhrhace rial having a low coeiiicient of expansion, and chamber extendmg circularly about h Y can be carried out in a manner well known in tort. I .Heat may be supplied to the zones H]. ep y suitable t by e combustion: of The lower part of the refractory ring 93 is fuel, or elect ically. These zones are m the 0pm2 to id 3 5 having opposite width w h the p g y y to nozzles. 97. The latter discharge" premixed malhtelh y desued temPerCethTe g w as and air in' correct combining ratio However, regardless of the Specific m through the opposite portions 92a of the-said h t the Said zones, the Sa comprise ring. The said orifices may constitute-parts radiant refractory areas that heat the retort f a i l burner 98, To l th burner byradiation. \These areas are designed to be ith th refractory ri'ng,'a strong hi h m Pa ticular y adapted f if r radiation perature cement 99 may be used, supported ,of heat, whether the heat be suppliedthereto on ablock 100 which rests on a plate 101.

the retortby internally fired devices outside peratures may be obtained therein. It will of the retort which, on becoming hot, probe appreciated that the rings constitute strucv'ide large masses of radiating refractory. tural shapes that can be efficiently, supported body, and none of the gases of combustion by the furnace wall over alarge area ofthe needcome in contactwith the wall of the rerings.

To protect the orifices 97 against overheating, they may discharge into conical spaces 102. These spaces serve to convey the gases at high velocity to the surfaces 96. The

ring adjacent to the said surfaces may be thickened as shown at 103 to provide sulfi-v cient interstitial area at the surfaces mentioned for rapldly receiving the gases without excessive resistance. An upper portion 104 10 of the ring is unglazed to provide an opening for the escape of the burnt gases.

The fuel is consumed in theintcrstices of the pieces of refractory 92, with flameless or surface combustion, the principles whereof are well known. It is intended that the mass of the refractory rings be sufficiently great in proportion to the fuel consumed, that, after the furnace has been thoroughly heat soaked and at equilibrium, the temperature thereof be substantially uniform. It'will be evident to those skilled in the art, that the said refractory rings can, if necessary, be modified to suit different operating condition? ,and yet cause the temperature thereof at 5 the lower portion of the retort to be substan tially equal to that at the upper part thereof, regardless of whether this result he accomplished by providing a solid thick wall along the said ring adjacent to the wall of the retort, or providing a wall of this type of varying thickness.

WVith reference to surface combustion, it will suflice to briefly state that the gaseous fuel is completely consumed with little or no excess oxygen. When the charge of gas and air is ignited in contact with the surface of the refractory material, the heat developed is so intense that the refractory becomes rapidly incandescent. Due to radiation of heat from one piece of refractory to another, the entire mass of the porous refractory body becomes ultimately incandescent,'so that the entire ring becomes an efficient radiating medium. The glowlng refractory material acts as a 5 catalyst and causes an almost instantaneous combustion. The waste gases pass out through the interstices of the refractory material at any suitable point in the ring, and are utilized in heating the low temperature end of the retort.

0 bly fitted therein a hollow valve 112 having an opening 113 to communicate with the tube 110. Connected in any suitable manner to the valve 112 isa coaxial Venturi tube 114 to pass the mixture of gases intothe burner 98. Extending from the said valve is a spinor pulley 1120. Thus a belt connection may serve to regulate from a central point all of the said valves for the different combustion zones. Each valve may be set at any desired predetermined position with respect to the other valves, and each pulley may be of a different size so that the rate of opening or closing of the valves may be varied as among themselves.

After leaving the refractory rings, the gaseous products of combustion enter the openings 115 in the top wall of the furnace. These openings are positioned between adjacent refractory rings, and communicate with a by pass 116 in the said Wall. This by pass permits the products of combustion to pass to the inlet end portion of the retort where they are circulated spirally about the retort, since this portion of the furnace is not provided with the refractory rings. Thus a temperature gradient isobtained which is desirable in the reduction of minerals. The spiral travel of the gases may be obtained by. placin g spaced segmental plates 117 and 118 at the top' and bottom of the furnace chamber between the wall thereof and the retort. To prevent short'circuiting of the gases from the refractory rings to the spiral passages 119,

the retort'has a plurality of annular ribs or flanges 120 extending into corresponding recesses 121 in the furnace wall; and a similar flange 122 is provided at the inlet end of the retort to guard against leakage of air into the furnace chamber and prevent oxidation of the retort. From the spiral passages, the products of combustion enter an outlet 123.

To automatically regulate the temperatures and pressures in the retort, a central control 125 is provided. This includes thermocouples 126 and 127, the former of which may extend into the compartment 59 of the retort, through the end plate 26, while the latter may be disposed externally of the retort in proximity to the same compartment. A third thermocouple 128 is positioned outside of the retort adjacent to the wall of the retort compartment 57 Each of the thermocouples may be connected to suitable induction coil and magnets 129, 130, and 131a,

respectively. The latter operate a control means, as, for example, the corresponding valves 112 by any suitable means including levers 131 connected to the pulleys 116. Induction coils and magnets 132 to 135 are provided to control throttle valves 136 to 139 of the primer movers or vacuum pumps condevices 132 to 135 are connected in parallel.

The devices 129 to 131a may be in series with the circuit 140, 141 by means of wires 142,

and rheostats 143 may be provided forthe devices 129 to 131a. Power lines 144 supply I electricity to the several devices. The rheostats are operated by the induction magnets, and the relation of the two is such that the temperature pressure ratio may be kept constant, though one of these factors should accidently change.

In Fig. 14 is shown a modification of the invention, wherein the rings are arranged to discharge the waste gases at a point where the temperature of the gases has dropped sufficiently to be incapable of imparting heat to the ring. Thus the ring 91a has openings or is unglazed at 916 intermediate of the upper and lower ends of the ring. The waste gases that-leavethe rings at 91?) enter recesses or passfiges 24a in the wall of the furnace 24 and fiow upward exteriorly of the rings into the outlet 116. The said passages 24a may be closed by the rings themselves, and the waste gases will directly heat the upper side portions 24?) of the furnace, reducing the loss of heat by conduction through the furnace walls, and afiording a high degree of uniformity in the heating of the retort 21.

In Figs. 15 and 16 isshown a modified arrangement of the rings 91. This embodiment 145 is disposed circularly about. the heating chamber or retort 21, which it heats primarily by radiation, as above described, and may be similarly mounted within a furnace such as 24. It includes a tubular refractory member 146, that has been suitably moulded and baked. The lower portion of the said member is enlarged to constitute an enclosure 147 which is analogous to a combustion chamber. Theupper portion of the member is in the nature of a ring 148 that conducts the hot products of combustion from the chamber 147 around the retort to discharge the same through an opening 149, whence they flow through passages 115 into the by pass 116 as'hereinbefore described. The chamber 147 is open at its bottom at 150 to receive a hollow tile 151. The latter may be open at the bottom, but its upper closed end 152 is spaced from the inner wall 153 of the tubular member. Positioned in the said tile 151 is a burner 154, having a plurality of oppositely extending heads 155 lying in a plane at right angles to the axis of the tubular member 145. Each of the heads has a plurality of small orifices to discharge the premixed air and fuel through openings 156 in the coacting opposite walls of the tile. To protect the burner, refractory blocks 157,

- 158 are disposed thereabout, which also centrally position the same. Supporting the tile and also closing the bottom of the tubu; lar member 145 is a refractory member 159 which rests upona plate 159a. Preferably completely filling the'tubular member 145 .is a porous refractory material 160 that en closes the tile 151. This material may be in the nature of pieces of broken'refractory upon which the gas and air mixture enter afterpassing through *the openings 156 in the tile to burnwith surface combustion. The sizes of the pieces of refractory 160 is predetermined to permit the required speed of travel of the products of combustion through the what thick, itmay be perforated as shown at 163 to provide openings through which the incandescent refractory 160 may directly radiate-upon the retort. These radiant heat openings may also vary in size to afiord uniform heating of the retort. It is noted that the bottom portion 164 of the inner wall 153 is imperforate to guard against any possibility of undue transmission of heat to the retort at this point. That a portion of the products of combustion may be in direct contact with the retort may be of lesser importance since the material of the latter is well adapted to resist the action thereof. As the radiant heat acts between adjacent pieces of refractory in the ring, these pieces will all become incandescent ultimately, and thus afford the main source of heat for the retort. To ignite the fuel, removable plugs 164a may be provided, accessible at the bottom of the furnace 24.

' In Fig. 17 is shown a modified arrangement of the heating rings, which can be practised with either form of ring hereinbefore described, and now denoted as 165. These rings 165 are disposed along planes forming an acute angle with the retort, so that the effective heating zone of each ring is defined by its projected area 166. As the retort rotates a high degree of uniformity of heating may be'obtained. The said rings may be arranged to space the projected areas, or the angle of inclination or widths of the rin s may be varied-for the successive rings, to o tain a .temperature gradient.

In Figs. 18 and 19 is shown a modified rangement of a partition or wall 167 for a lower portion of the disc, the same is provided with an opening or passage 17 5 laterally positioned according to the surface 176 of the charge in the retort, that seals the said passage through which the charge passes due to the slope of the retort. In making the passage 175, an arcuate flange 177 may be formed to fill that portion of the groove adjacent to said passage.

In Figs. 20 and 21 is shown a further modificat-ion of the invention which includes a partition or wall 1'. 8 and having a passage 179 for the movement of charge that seals the same. A slight clearance may be observed at 180 between the edge of the partition and the wall of the retort.

It will be appreciated that the partitions 55 are adapted for a variable charge in the retort, while those shown at 167 and 178 require a definite minimum charge to seal the passages therein. Furthermore, the partitions 55 are adapted for a positive movement of the charge at any predetermined speed.

In conclusion, it is desired to point out that considerable space has been devoted herein to the exposition of various embodiments of the invention, in order to obtain a clear, full, and'operative disclosure; but it is not desired to convey the impression that the means shown are substantiallyuthe only ones that can be used. Thus while heating members of ring form have been shown, circular heating zones can be created in the furnace by other means, or burners well known in the art. Further, the retort, the conveying means for the charge, and the partitions'can all be changed, separately, and collectively, within the scope of the broad invention.

I claim:

1. An apparatus of the character described, including a chamber through which the charge therein is adapted to move, means to heat the chamber. means to divide the chamber into a plurality of compartments to prevent the fiow of gases from one to another of said compartments and to cause the charge to move through the successive compartments, and positive means for forcibly exhausting the gases from the retort compartments.

2. A device of the character described, including a rotary heating chamber, and relatively stationary means therein dividing the U same into a plurality of compartments and preventing a-free flow of gases from one to another of the same, said chamber making an angle with the horizontal to cause the charge to move therealong, said means having a restricted opening through which the charge passes in its movement aforesaid, and an annular series of pockets {rotating with the chamber, the pockets successively communieating with said opening in relativelvclose relation thereto.

3. Adevice of the character described, in-

charge on the lower wall thereof,.said chamber having means therein below its axis of rotation to receive a part of the charge,-said means coact-ing with the chamber to move therewith on rotation of the latter to a position above the said axis, and means coacting with the first mentioned means for sealing the charge therein and causing the same to be discharged back onto the lower wall at a point relatively in advance of that at which the charge was received.

4.. A device'of the character "described, including a retort, means to divide the same into a plurality of compartments-and restrict the flow of gases between the compartments, and means to receive and enclose successive batches of the charge to cause the'same to move from one to another of the compartments past the first mentioned means.

5. A device of the character described, including a retort divided into a plurality of compartments through which the charge is successively movable, means separately exhausting the gases from the compartments, and means heating the compartments to difjerent temperatures. v

6. A device of the character described, in-

cluding a plurality of compartments through which a charge is successively movable, means to heat the compartments at temperatures that increase from the first compartment to receive the charge, to the last compartment, and means to exhaust from the compartments the gases therein.

7. A device of the character described, including a retort divided into a plurality of compartments through which the charge is successively movable, means separately exhausting the gases from the compartments, means heating the compartments to different temperatures, moval of finely divided material from the compartments with the exhausted gases.

8. A device of the character described, including a rotatable retort, means therein dividing the same into a plurality of succesand means preventing the re- 9. A device ofthe character described, in-

cluding a heating chamber having a plurality of compartments, means for moving the charge through the successive compartments, means to heat the compartments to difi'erent temperatures, and means to separately remove from the compartments the gases there- 10. A device of the clqracter described, in-

. gas

eluding a heating chamber having a plurality of compartments, means for successively compartments to different temperatures, and

means to separately remove the gases from i the compartments.

11.'A device of the character described, including heating means having a plurality of compartments coacting for the movement of. the charge through said compartments, and means for maintaining different gas pressures in the difierent compartments.

12. A device of the character described, including a retort having aplura'lity of compartments, said retort having means for moving the charge successively through the compartments, and means for the separate removal of the gases in the compartments.

13. A device of the character described, including a plurality of closed compartmcnts, means for moving a charge through said compartments, heating means and gas exhausting means'for said compartments, separate control means for the heating and exhausting means, and a unitary means for automatically regulating both control means.

14. A device of the character described, including a plurality of compartments, means for moving a charge through the compartments, means to heat the compartments according to a temperature gradient for the compartmentsithat increases in the direction of movement of the charge, and means to maintain a pressure gradient for the compartments that decreases in the direction of movement of the charge.

15. A device of the character described, in-. cluding a heating chamber, means to vary the temperature therein, means to vary the pressure therein, and unitary means to automatically regulate the first and second mentioned means.

16. A device of the character described, including a closed heating chamber, and means for controlling the temperature therein, m'eans for exhausting the gases therefrom,

means forcontrolling the exhausting means,

and other means for simultaneously operating both controlling means so that an increase in temperature is accompanied by a decrease in pressure.

17 A device for the reduction of pulverized ores, mixed-with coal, including a rel tort, means for heating the retort from the outside, continuously fed through the retort, and means for forcibly exhausting from the retort the gases therein, the exhausting means ineluding separate tubular elements communicating with different parts of the retort for separately withdrawing the gases from the zones inwhichthey are generated.

means, for causing a charge to be 18. A device for the reduction of pulverized ores, including a closed retort, means for heating the same from the outside, the retort having means for continuously feeding a charge therethrough, means for forcibly continuously exhausting the gases in the retortand to produce a decreased pressure therein, and means coacting with the exhausting means to prevent the removal of finely divided solid materials with the exhausted gases.

19. A eluding a retort, the same having means ,for continuously feeding a charge therethrough, means for externally heating the retort according to a temperature gradient, and means for forcibly separately withdrawing the gases in the retort from the different-respective zones therein in which the gases are generated.

20. A device including an elongated retort, and means for heating the same from the outside, said means including a plurality of thin walled, internally fired elements extending around the retort for radiating heat thereon, said elements being of varying width with respect to each other for maintaining a temperature gradient in the retort.

device for the reduction of ores'in-

Images