US2297289A - Furnace discharging device - Google Patents

Description

o. D. COLLIS ETAL FuRNAcE DISCHARGING DEVICE original Filed July 31,'1959 Sept. 29, 1942.

Vproduced Patented Sept. 29, 1942 2,297,289 FURNACE DISCHARGING DEVICE Oliver D. Collis, Eldred C. Brace, and Emery 0.

Thompson, Clinton, Iowa, assignors to The Collis Company, Clinton,

Iowa

287,476, now December 16,

Iowa, a corporation of original application July 31, 1939, serial No. Patent No.

1941. Divided and this applica- 2,266,005, dated tion June 9,1941, Serial No. 397,280

2 Claims.

This case is a division of our application liled July 31, 1939, under Serial No. 287,476, now Patent No. 2,266,005. f

The apparatus of our invention which is adaptable for the heat treatment of various loose materials, such for example as the roasting of raw ores, is essentially a circular rotary hearth furnace in which the hearth rotates in an annular tunnel constructed of insulating material. While the advantages and objects of Vthe present furnace are many, the features with which this application are particularly concerned relate largely to the means by which the treated material may be removed from the furnace hearth.

A mechanism containing a suggestive embodiment of our invention is `illustrated in the accompanying drawing in the manner following:

Figure 1 is a fragmentary top plan view of the annular roof broken away to'exhibit therebelow a rotary hearth with which is associated the present unloading mechanism;

Fig. 2 is a transverse section, on an enlarged scale, through the hearth and roof therefor, taken on line 2--2 of Fig. 1; and

Fig. 3 is a detailin perspective of the delivery end of the unloading screw shown in Fig. 2.

While reference throughout the specification is made to'an ore roaster, as a specific application of our invention,'it should be understood that it may be applied to the heat treatment of any loose materials under controlled conditions, or simply to the heating, or even the drying (with or without heat) of such materials, as a continuous process wherein the material, while disposed upon a hearth, is subjected to repeated stirring, turning over, and exposure of fresh portions of its mass, during the treating period, and (optionally) previous and subsequent thereto.

Referring particularly to Figs. 1 and 2, the annular hearth comprises a ring-shaped floor I bordered adjacent its inner and outer rims by low walls II and I2, respectively, all desirably from suitable refractory materials, and carried upon a metallic base plate I3 supported upon ledges which are extended laterally. from aprons I4 and I5 adjacent the inner and outer walls, respectively. The hearth base plate is supported upon and reinforced by cross beams I6 which are rested upon inner and outer circular beams I'I and I8, respectively. Circular flanged tracks I9 and 20 are fltted to the underside of the inner and outer circular beams I'I and I8, respectively, each track being ladapted to ride u-pon the upper face of a plurality of rollers 2 The depending aprons I4 and I5 are positioned within circular troughs 30 and 3|, respectively, containing a suitable uid material (water, sand, etc.) to a level 32 which is above the lower edge of the apron, whereby to provide a seal `therewith. Each trough is supported upon a plurality of circularly arranged piers, the inner ones being designated as 33 and the outer ones as 34, the space between these piers and below the hearth being open or closed according as may be desired. Any suitable drive (not shown) may be provided, by which the hearth is slowly revolved upon the several wheels whereon the rails are adapted to travel.

Extended vertically from suitable foundations to the outside of the lpiers 33 and 34, are supporting beams 50, spaced at suitable intervals and interconnected with each other and certain radially extending overhead beams 5I. The vertical beams support an annular roof which surmounts the hearth in spaced relation thereto. As shown, the troughs 30 and 3l are each formed withran outwardly extended bracket 52 supporting a ledge 53 from which rises a retaining plate 54 connected at intervals with the vertical supports 50 so as to be sustained thereby. -Bllilt upon each ledge and extending upwardly -along the inner face ofA each retaining plate is a wall 55 supporting at its upper end the opposite edges of an arched annular roof 56, the walls 55 and the roof supported thereon being desirably made, in whole'or in part, of a suitable refractory material. Also we provide through the inner and outer Walls 55 a plurality of draft openings 58, positioned, if desired, so that their lower edges are about opposite the upper edge of the inner low wall II of the hearth. Each such opening may be closed, in whole or in part, by a suitable door (not shown). Through the outer wall 55 is an o-pening with a surrounding lining 59 of refractory material, a burner 60 being tted into such opening where it is surrounded by the refractory material through which is a central passageway 6I forming a discharge orifice for flames which are projected from the burner into the annular space between the hearth and roof. The burner is connected with a conduit 62 leading to a source of fuel supply, preferably oil or gas. It will be understood that a number of such burners are located adjacent an outer wall of the annular hearth, the positioning and spacing of such burners being preferably'according to some such plan as will hereinafter be explained.

Extending through the roof is a chute leading downwardly from an overhead bin or hopper 86 wherein is maintained a supply of loose material to be treated. As by means of suitable valve mechanism (not shown) the gravity iiow of the material through the chute may be controlled so that it will be deposited upon the hearth continuously at a rate which may be handled to best advantage. As shown, the lower end of the chute is connected to a neck 81 extending upwardly from a distributing hood 88 which extends transversely across the hearth, there being baffles or other walls arranged within the hood to deflect and guide a portion of the material to points adjacent the opposite rims of the hearth. The Ibottom side of the hood which is open may be positioned close to the iloor of the hearth. The hood is adjustably supported as -by a pair of bolts 9| each equipped with a turn buckle 92 by which to vary the height at which the hood is supported-a desirable objective in view of the diversities of the materials and conditions to be dealt with. Adjacent the hood and extending upwardly from a point close to the hearth is a conduit |00 which passes out through the housing to a scrubber, or directly into a stack, for discharge of gasses or products of combustion into the atmosphere.

For a rabble mechanism we may employ a plurality of spiral blades |55 each extending continuously along a shaft |56 which is disposed transversely over the hearth, the blades at their lowermost points lying close to the hearth iioor so as to engage with the layer of loose material that rests thereon. Opposite ends of each shaft are journaled for rotation in suitable bearings, the shaft being extended beyond the inner bearing to carry a sprocket wheel |58 over which are trained chains connecting with a power transmission (not shown). By suitable connections, a number of spiral blades, each extended transversely across the hearth, may be driven in unison so that the material which is moved along with the hearth is constantly turned over and stirred. The pitch of the blades on alternate rabbles may be reversed so that stirring of the ore is equalized in the direction of its opposite rims.

Referring now to Figs. 2 and 3, we have shown an unloader comprising a shaft |10 mounted to rotate transversely over the hearth at substantially the point where the treated material is to be removed therefrom, and equipped with a sprocket wheel |1| (or two, if desired) by which power may be conveniently transmitted thereto. Carried upon this shaft is a hub |12 mounting a large diameter screw |13 having the lower portion of each convolution in close proximity to the hearth so that, when operated, the loose material will be engaged thereby to be shifted transversely towards the outer hearth rim. At the outer end of the screw we have affixed a radial ange |14 extending outwardly close to the proximate rim of the hearth, adapted to act upon the loose material which may have collected at that point, first raising and then dropping the material upon a ledge |15 from which it descends along an inclined chute |16 to a dis-charge station (not shown).

The material to be treated is conveyed to the hopper'or bin from which it is released for a controlled discharge into the distributing hood immediately over the hearth. As the hearth rotates it carries the material with it concentrically.

It advances along with the hearth through nearly 360 of movement, returning to approximately its point of introduction. The material may remain on the hearth for one or more revolutions, the desirability of this depending upon various factors, such as temperature, nature of material, speed of rotation, etc. stirring of the ore is accomplished by the several spiral rabbles which are spaced apart, as desired, each revolving about a horizontal axis which remains stationary. The combination of the rotating hearth traveling against the rotating rabbles produces a slow, persistent turning over of the material on the hearth bed.

In conclusion we would have it noted that in the` present mechanism there is a positive movement of all the material, as it advances along upon the hearth bed, the material being iinally returned to its original point of entry; and there is a thorough stirring of the material due to the unique movement occasioned by the rotatable advance of the hearth while continuous rotary movement of the several spiral rabbles proceeds. Such a hearth, which advances through a rotary path, permits an absolute control of such factors as time, temperature, zoning and movement of the material particles.

l. A treating mechanism in which is comprised an annular hearth mounted for rotation about a iixed axis, a stationary annular roof supported above the hearth, means for delivering loose material upon the hearthl and means for removing the loose material from the hearth at a xed point in the rotation of the latter comprising a screw mounted for rotation about .a horizontal axis extending radially of the hearth at an elevation thereabove such that the lower portion of each convolution of the screw engages within the bed of loose material upon the hearth, a discharge chute adjacent one end of the screw, and means carried by the screw convolution at the outer end thereof proximate to the chute for lifting material from the hearth to a point of gravity discharge through the chute. an elevated unobstructed lateral passageway to the chute being arranged to receive material from the material elevating means of the conveyor when such means is in an elevated position.

2. A treating mechanism in which is comprised a hearth movable through a fixed path, and means for removing loose material from the hearth at a xed point in its movement path comprising a screw mounted for rotation about a substantially horizontal axis extending over the hearth at an elevation thereabove such that the lower portion of each convolution of the screw engages within the bed of loose material to advance the engaged material along the hearth in a direction axially of the screw, a discharge chute adjacent the delivery end of the screw, and means proximate to the Vchute connected for rotation with the screw adapted to engage and lift the advanced material from the hearth to a point of gravity discharge through the chute, an elevated unobstructed lateral passageway to the chute being arranged to receive material from the material elevating means of the conveyor when such means isin an elevated position.

OLIVER D. COLLIS. ELDRED C. BRACE. EMERY O. THOMPSON.

Images