US2673081A - Heat processing system and furnace - Google Patents

Description

March 23, 1954 H. M. FAY ET AL 2,673,081

HEAT PROCESSING SYSTEM AND FURNACE Filed Sept. 26, 1950 2 Sheets-Sheet 1.

FIG. FIG. .2.

|e 25a 28 H 33 23a INLET- /E 22 4 2 70 *9 Z'mventorS:

HERBERT M. FAY,

MYRON RJGILLETTE,

' March 23, 1954 H. M. FAY ET AL 2,673,081

HEAT PROCESSING SYSTEM AND FURNACE Filed Sept. 26, 1950 2 Sheets-Sheet 2 30 O I 530 i0 H 3nventor5; HERBERT M. FAY, MYRON R. GILLETTE,

Patented Mar. 23, 1954 HEAT PROCESSING SYSTEM AND FURNACE Herbert M. Fay and Myron R. Gillette, Salt Lake City, Utah Application September 26, 1950, Serial No. 186,769

14 Claims. 1

This invention relates to a heat processing system and furnace.

Principal objects of the invention are:

To provide a multiple-zone furnace structure wherein greatly varying requirements in the heat treatment of certain substances are controlled step by step so as to achieve complete processing in a single pass through the furnace.

To economize fuel by making efiicient use of the generated heat.

To be adaptable to the efficient production of finished materials of many different kinds.

To attain a high degree of precision and uniformity in meeting given material specifications.

To attain simplicity, convenience and durability in the furnace structure.

Other objects will become evident hereinafter.

A feature of the invention is that it is especially adapted to the processing of all kinds of raw materials that require heating in successively increasing temperature stages. In the successful treatment of many different kinds of substances We have found that it is highly advantageous as a first step of processing, to remove the film of moisture which, in the natural condition, surrounds the individual particles of the material. We accomplish the removal of the moisture film immediately after the raw material enters the furnace, by subjecting the particles simultaneously to moderate degrees of agitation and of heat. Furthermore, the successive stages or steps of a process are accomplished in a single pass of the material through the furnace.

some of the peculiar conditions encountered in the processing of discrete raw materials such as ores, earths, minerals and so on, are that different specimens vary greatly in composition. In the sizing of such materials it is practicallyimpossible to bring about any substantial uniformity in the actual dimensions of the individual particles. Obviously, large particles require a longer time to reach a critical processing temperature than is the case with small particles.

It is a further feature of the invention that various zones are provided in which the temperature and other processing conditions are graduated and are selectively regulable according to the varying compositions and sizes of the particles passing through those zones.

- some materials are most efficiently and economically processed when exposed to the direct action of a flame obtained from the combustion of natural gas, artificial gas or oil. The elapsed time interval of exposure of a material to the action of a flame to effect the desired degree of treatment, will vary with the size of the particle.

As a means of controlling the elapsed time interval required, an adjustable device is provided whereby the length of time particles are suspended or held in the flame, can be sensibly varied.

It happens, too, that in cases where large ore particles are exposed to the sustained action of a flame for the length of time required to raise the center portions of the particles to the required critical temperature, fracturing occurs.- Fracturing is not desirable since many commercial products require the utilization intact of the larger particles.

Therefore, as soon as an ore particle has approached the critical point, it must be coincidentally cooled to avoid over-treatment. For this purpose, cooled air is introduced into a cooling chamber which is a part of the exhaust system provided for each burner unit of the multiple burner feature of the furnace. An adjustable device is also provided to enable an operator to control the volume of cool air necessary to quench the particles.

Since the density of a material greatly affects its capacity for heat absorption, and since proper dispersion of the particles in a mass affects the extent of exposure to heat absorption, the selective control of these factors afforded by the invention is important.

In the furnace of the invention it is advantageous to arrange the successive treatment zones vertically in the form of a stack or shaft. In a preferred arrangement, the first or moderate heating zone is at the top and in proximity to the point where the raw material enters. Thus, all portions of the raw material are first subjected to a light processing heat for removal of surface moisture. After such removal of surface moisture, those particles which require only a moderate temperature, are removed after passing into or through the second zone. In the subsequent lower zones, those particles which are not susceptible of complete treatment in the preceding zones, automatically determine their own zones of process completion and ejection from the furnace.

In the accompanying drawings, which illustrate one embodiment of the apparatus of the invention:

1 represents a side elevation largely in section taken on the line l--l in Fig. 2;

r Fig, 2. a rear elevation largely in section taken on the line 2-2 in Fig. 1;

Fig. 3, afront elevation;

24, 25, 26, 27. Processing commences in the upper:

zone 24 and is continued in the successive zones 25 to 21. Rotatably disposed in the upper zone 24 is a tubular feeder and drier 28. The feeder for illustration, is supported by trunnions 29 and 3D. The tube 28 is driven by any suitable means, in this instance, by an annular sprocket wheel 3| fixed on the tube. In turn the sprocket wheel may be driven by any suitable means, for example, a sprocket chain 32 that extends to an electric 'motor" (not shown). The'front" portion ofthe tube 28' is retained in'place by means of an'annular thrust collar' 28a that bears against a thrustroller'33; while the 'rear'portion ofthe tube is subject to the guard rollers'e l. At35 is a hopper disposed to receive raw material which flowsfrom the spout 35, the latter being extended into the tube 28: The "tube can be rotated -in either direction, the action upon the material passing through the tube-being the same in both cases. The'tube 28 is particularly well adapted for use with thepresentinvention, for the reason that in rotating, the material passing through the tube tends to be carried upwardly becauseof itsfric'tional cohesion to the inner surface of the tube, until gravity acts to pull the material back. Thus thepath describedby the material with reference to the inner surface of the tube, as it slides back in successive steps, islargely zigzag. This zigzag motion constantly distributes and redistribute-s the passing material, thereby exposing fresh particles to bothcontact with the tubular shell and to a current of air thatenters through a pipe 3'! at the lower end of the tube. As will subsequently appear; the tube is heated largely by the hot gases which ascendfrom the lower zones of the furnace. In thegradual descent of the materialthrough the tube, it" is constantly exposed to the current of air coming in through the pipe 31, whichcurrent assists to eificiently dry thev raw material; The upper end of the tube 28' is open so that there is no obstruction to the: passage of the airand" vapor through the tube, which is inclined;

baflles 3'9 and 40 into a hopper 4| forming part of a traveling material distributer 42'. This distributer 42 includes the upper, or head section 43 and the lower trough sectionM, these sections being held together by exterior bands 55' which are'welded'or otherwise connected to the respective sections. The upper section 43' is. rigidlyconnected to the hopper 4| by means of welding or'otherwise, and the hopper in turn is rigidly connected to two guide bars 46. These guide bars are movable longitudinally on a supporting beam 47f and in a guide bearing 48, the latter being attached to the wall 2|. The beam 41 is preferably stationary and extends rigidly from side to side of the housing 20.

Substantially concentric axially with the distributer 42 and extending'into the space between the hood 43 and trough 44 is a burner which includes a fuel tube 50. Fluid fuel such as gas,

enters through the tube under pressure and after ignition tends to create a blast somewhat after the manner as indicated at 5|. The blast is composed largely of products of combustion and carries forward and distributes the stream of material that drops from the drier 28 into and through the hopper 4|. The fluid current 5| is designedv to be selectively controlledby suitable valve means, not shown, to effect the proper conditions demanded by the dried material which drops into the current in a further processing step. Such particles of the material as have been susceptible to light treatment, are carried upwardly as indicated at 52, into and through an outlet pipe 53 which leads to a suitable point of disposal (not shown). This lightly treated, discharged material constitutes as a rule, a finished product ready for market. Such portions of the material which require a greater degree of treatment, are discharged from the distributer approximately asindicated at 54.

The greater portion of the particles rejected along the lines 5s drop into a chute 55 which-in this instance, is composed of the side plates-56 and a slidable bottom plate 5?. The side plates 56 are inclined inwardly and'are spaced apart so as to accommodate the slide El, as indicated in Fig. 6. The side plates 56 are flanged at 58- and are'rigidly connected to each other by means of cross bars 59, the latter being welded 'or'otherwise attached to flanges 58. The upper portions of the sideplates as may be suitably attached to supporting angles 5%, which in turn are connected to the respective walls 2 I. The rejected material from the distributer 42'descendsby gravity along slide 5? which may beadjusted soas to'drop. the material into a traveling'hopper Ma that constitutes part of a second traveling distributer 42a.

The second distributer preferably is similar "to the one at 42' which has previously. been described in detail. This second distributer 42a is provided with a burner 49a, served by a fuel tube 5011, these. being similar to the burner49 andfuel tube 50 previously described. The products. of combustion which are discharged throughthe burner 49a act along the lines 5m in a manner similar to thatdescribed inzconnection with the lines 5|. It will be understood that the rejected material 54 which gravitates alongther slide 5l.is' discharged into and passes through the hopper Ma and in turn encounters'the second current 5100 of combustion gases. In the current 5|a,'. those particles which have been incompletelyprocessed, are here subjected to such selectively changed processing conditions'as may seem desirable. Some of the particleswhich are discharged from the distributer 42a, and more especially the lighter portions thereof, may travel upwardly as indicatedby the lines 52a, andpass into the discharge pipe 53a. The heavi'erand less completely treatedparticles are deposited in a chute 55a, which is similar in:construction and, operation to' chute 55 hereinbefore described; The chute 55a is provided with'a slide S'Iwwhih is manipulatedin a manner'similartoithat shown: at 51. The result is that those particles of the material which require's'till other processing. conditions, are discharged'from the. distributerifla' substantially along linesiindicatedat" 54a: These particles gravitate along the slide 51d and are discharged somewhat as indicatedat 6|. "The" particles at Glare subjected':to aablast 62of combustion gases coming through; a burner? 63'; which is served'by afuel'tube 64. 'The.-li'ghterf of the particles at 6| are. carried iforwardirbyrthe-i blast along the lines 65 and pass directly out of the furnace through the pipe 66. The heavier of the particles at 6| pass along and out from a trough 61 with a tendency to settle on the inclined plate 68 which is slidable on supporting angles 14, the latter being fast on the housing wall.

At 69 is located an adjustable cold air inlet and at 10 is an inspection opening normally covered by a plate 1|. A removable end plate 12 is providedfor access to the interior of the furnace.

Connected to the discharge pipes 53 and 53a, respectively, are adjustable cold air inlets 13 and 13a which function as suction controls for the purpose-of regulating the current of finished material passing through pipes 53 and 53a respectively.

The slides 51 and 51a, as well as the inclined plate 68, protrude from the housing so as to be easily manipulated by an operator to the required adjusted position for any particular purpose. Similarly, the guide bars 46 and 46a protrude for adjustment or other purposes.

The pipe 31 has a branch 15, and the tubes 50 and 50a, the respective branches 15 and 16a. These branches are largely for the purpose of introducing reagents, for example, in the form of gases or vapors in the treatment of the materials passing through drier 28, and through the distributers 42 and 42a.

The zones 24 to 21 are not sharply defined, but have more or less variable limits that are brought into being by the selective manipulation of the operative devices provided in the respective zones.

The apparatus of the invention is peculiarly suited to practice a system of heat manipulation based on the principle of a thermal interval. This term we choose to define as the time intervening between recurrences of similar processing states. In other Words, it makes positive heat exchange or heat transfer at any given or required period of time in recurring or multiple states or stages. This system has many advantages over the prolonged or sustained method of heat application and heat transfer.

Employment of the thermal interval principle permits diffusion of heat throughout the absorbing mass thus maintaining greater uniformity of temperature and avoiding extreme contrasts between the outer or exposed surfaces and the interior or center of the mass.

Each terminal interval may be one of high or low degree of temperature as required.

The number of superposed zones of processing can be indefinitely increased depending upon the nature of the thermal intervals employed. Each additional zone means the repetition of the mechanical determinants.

The apparatus may be used for dehydrating, calcining, sintering, nodulizing or other process where uniform heat diffusion is required or desired.

In the invention, an important difference is recognized between merely removing the surface film of natural moisture from discrete material, as mentioned earlier herein, and dehydration. Dehydration, as that term is herein used, means largely the handling of the combined water of a substance, such as the water of crystallization, in a way or ways that a predetermined result is advantageously reached. For illustration, in some materials as found in nature, if the water of crystallization is removed gradually, either in a single step or in multiple steps, the end product may have certain characteristics. But if, on the contrary, the same water of crystallization is subjected to heat gradations that are speeded up, an end product having far different physical or chemical characteristics may be inevitable.

The manner of applying the requisite heat selectively by means of the adjustable distributers 42 and 42a and the respective burners and appurtenances, appear to make results possible which have heretofore been unattained. The superposed arrangement alone of these distributors and the intercombined feed chutes eifects an economy in fuel consumption and in heat distribution that are distinctly new.

What is claimed is: l

l. A multiple-stage processing furnace comprising a furnace structure enclosing a plurality of successive processing zones superposed one upon another, each zone being nominally defined by means of a blast-generating burner directed transversely of the furnace; means operative to selectively control each blast-generating burner; distributer means associated with each burner for receiving and disseminating within it the blast of the burner; each said distributer means after the first zone including a longitudinally extending trough; an inverted trough in opposition to, and spaced longitudinally apart from, the firstmentioned trough, to provide longitudinal openings between the troughs for causing the furnace atmosphere and the blast to blend with each other; and means for delivering comminuted material to each distributer means.

2. A processing furnace according to claim 1, wherein each longitudinally extending trough is a channel having in cross-section approximately the shape of a crescent with upstanding horns; wherein each inverted trough is a channel having in cross-section approximately the shape of a crescent with downstanding horns; and wherein each distributer means after the first zone includes a material-receiving traveling means from which comminuted material from a previous zone passes into the correspondin distributer means.

3. A processing furnace according to claim 2, wherein each distributer means after the first zone includes guide means along which it is selectively movable with respect to the burner.

4. A processing furnace according to claim 1 wherein the distributer means of the first zone consists of an inclined, rotatable, tubular conduit extending across, and substantially defines, the uppermost of said processing zones.

5. A processing furnace according to claim 4 wherein is included nozzle means disposed to selectively direct draft fluid into and through said rotatable, tubular conduit.

6. A processing furnace according to claim 5 wherein is included a source of fluid reagent; and means operative to selectively dispense fluid reagent into and through said nozzle means.

7. A multiple-stage processing furnace comprising a plurality of superposed processing zones, the uppermost of said zones bein equipped with mechanism operative to convey material to be processed, transversely through said uppermost zone; means operative to heat and dry said material in its passage through said conveying mechanism; traveling hopper means operative to direct material from the conveying mechanism down through the lower zones; and means disposed to feed material into said conveying mechanism.

8. A multiple-stage heat processing furnace comprising a plurality of superposed zones, the uppermost of said zones containing heating and drying equipment disposed to conduct material across-such uppermost zone and to discharge the;

material attone endfthereof; a traveling processing unit/disposed to receive the material from thezone; said traveling processin unitbeing adapted toast. least partially define a blast dominated space; a burner adapted to direct a processing blastinto and through said space and to propel at least considerable portions of the dispersed material upwardly in a stream; suction means disposed to conduct such considerable portions away for disposal; and a source of raw material feeding into the heating and drying equipment.

"9. A processing furnace comprising a shafttype-vertically disposed structure having enclosingiwalls that define a multiple-zone processing space; an inclined tubular feeder located transversely in the upper portionof the shaft structure, said tubular ieeder having a material intake terminal outside and a material discharge terminal inside said shaft structure; a source of material; nozzle pipe disposed to direct a fluid current into the tubular feeder so as to pass from thematerial discharge terminal out through the intake terminal; actuating means disposed to rotate the tubular feeder; a traveling processing unit disposedto receive material falling from the tubularfeeder; blast means disposed to selectively direct ajfluid blast into said processing unit so as to engage material passing therethrough and to discharge the same so as to cause the discharging material to be divided into a fully processed portion: and a, partially processed portion; means disposed to receive and to conduct away, the fully processed portion; chute means disposed to receive the vpartially processed portionand to convey the same by gravity into a succeeding processing unit; another chute means disposed to convey the material from said succeeding processing, unitfor delivery into the lower part of the shaft; and means operative to remove the delivered material out of said shaft.

' v 10. A processing; furnace according to claim-,9?

wherein each of the said traveling processing units comprises a hopper mounted on longie tudinally adjustable guides; a hood depending;

from said hopper; a trough depending from said, hood; and blast-generating means disposedto selectively direct a fluid current through the space'included between said hoods and said-idepending trough.-

11.- A processing furnace according to claim 9;

wherein each of thechute means includes transversely; inclined side portions spacedapart from each other; and a longitudinal slide disposed to;

be moved back or forth and to variably cover the space included between said side portions. 7

12. A processing furnace, accordingto claim :9, wherein said removing means for delivered mate-- rial comprises fluid blast means; and outlet means extending from thefiuid blast means through a Wall portion of said shaft structure.

13. A processing furnace according to claim:12 wherein said outlet means includes an inclined plane located below and between the blast means. and said. wall portion.

14. A processing furnace according to claim 13, wherein said inclined plane is slidabl'y adjustable along the length thereof; and wherein a coldair inlet leads into the space below said 7 inclined plane.

HERBERT M.v FAY. MYRON R.- GILLETTE;

References Cited in the file of; this patent UNITED STATES PATENTS Number Name Date 241,108 Wieseb'rock May 3 1881' 290,115 Russel Dec. 11, 1883 371,715 Sonnet Oct. 18; 1887 702,004 Hopper June 10,: 1902 789,952 Anker etal. May 16, 1905 1,82%);270 Anderson Oct; 20, 1931 2,066,358 Musso Jan. 5, 1937 2529 1366 Bauer Nov. 7, 1950 Lu T anh.

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