US2676006A - Continuous furnace for converting material - Google Patents

Description

w. s. MARTIN 2,676,006r

CONTINUOUS FURNACEFOR CONVERTING MA'IlERItL 3 Sheets-Sh-eet 1 l April 2o, 1954 Filed Jan. 10, 1951 FIG. l.

April 20,v 1954 w. s. MARTIN CONTINUOUS FURNACE FOR CONVERTING MATERIAL Filed Jan. l0. 1951 5 ,Sheets-Sheet 5 FIG. 8,

n n M n INVENTOR WARREN S. MARTIN BY EZJ@ (f-mf:

LATTORNEY Patented Apr. 2f),A 1954 UNITED STATES EATENT OFFICE CONTINUUS FUR/NACE FOR GONVERTING MATERIAL Warren S. Martin, Massapequa,-N. Y.

Application January 10, 1951, Serial No. 205,264

(Cl. 26S- 26) 144 Claims. l

ment on my invention disclosed and claimed in issued Patent 2,471,882 granted to me May 31, 1949. The said patented invention shows in part a rotary hearth furnace of which the present invention includes improvements particularly ad vantageous tocontinuous operation and high temperature Work.

An important object of the invention is to provide a novel and advantageous form of furnace of the general character specified.

Another object of the invention is to provide a, rotatable-hearth furnace of the general character specified wherein air is supplied to the outer end of each rabble arm at one side of a partition, passes to the tip of the rabble and around the end of said partition and then passed at the other side of the partition to the outside of the furnace.

Still another object of the invention is to provide a furnace of the general character specified wherein the outer end of each rabble arm at the wall of the furnace is so mounted that the rabble arm can be released, picked up by suitable means and Withdrawn from the furnace to make Way for a replacement rabble arm.

Yet another obj ect of the invention is to provide a furnace of the character specified wherein the material to be treated is introduced near the periphery of the revolving hearth and is Withdrawn through the central part of the hearth and the current of gases flows concurrently with the material flow, from the periphery of the furnace to the center thereof and then upwardly through the top of the furnace.

A further object of the invention is to provide a furnace of the general character specified having a central opening in its roof for upward flow of gases, stationary rabble arms, a revolving hearth with a central projection beneath the opening in the roof and limiting the length of the rabble arms, a material inlet at one side of the roof opening anda material outlet at the periphery of the hearth.

A still further object of the invention is to prowith a .centralstationary pier surrounded by an annular rotary hearth, the material being fed to the annular hearth near its inner edge and rabbled, countercurrently to thegas flow, outwardly to the outer edge of the hearth where it is discharged.

In carrying out the invention, use is made of a furnace havinga low roof over a rotary hearth so as to assure contact of the hot gases with material on the hearth. According to one embodiment of the invention the rotary hearth has a central discharge opening and the material to be treated is fed to the rotary hearth near itsperiphery. As the hearthrotates the material is fed towards the central opening by means of inclined rabble blades on stationary rabble arms supported at their outer ends at the peripheral wall of the furnace. Each rabble arm is hollow and is divided into two parts by a longitudinal partition so that air supplied from a supply duct at the outside of the furnace to the rabble arm at one side of the partition will pass to the inner tip of the partition and back at the other side thereof to a discharge duct at the outside of the furnace. The connections between each rabble arm and supply and discharge ducts at the outside of the furnace are such that they can easily be disconnected after closing appropriate valves to prevent opening of said ducts to the outside air. The rabble arms can then be picked up by suitable means such as a truck having two projecting fingers to enter on opposite sides of the partition and means acting through said iingers to lift the rabble arm. The rabble armis then movedsidewise to a port having a door which has been opened for sidevvise movement of the rabble arm into the port preparatory to withdrawing the arm from thefurnace.

Another rabble arm may be placed in the position vacated by the arm thusr removed, and connected with the supply and discharge air ducts. The .opening around the outer end of the rabble arm may then be closed in any suitable manner.

According to a second embodiment of the invention the rabble arms are supported in the same manner as for the first form and at their inner ends are adjacent to a round pier or deadman on the rotatable hearth and occupying space beneath the gas outlet in the roof of the furnace. In this form the material to be treated is .supplied at the periphery of said pier and is gradually worked by the rabble arms to the periphery of the hearth where it is'discharged downwardly` and fed gradually through a gas seal to a discharge position. The central pier prevents movement-0f 3 the material to a central area from which it would not be removed.

According to a third form of the invention there is a stationary pier at the center of an annular rotary hearth and the rabble arms used for this form are not only mounted at the wall of the furnace as before but are also supported at their inner ends by said stationary pier.

Other objects, features and advantages will appear upon consideration of the following detailed description and of the furnace, in which:

Fig. l is a section taken along line I-I of Fig. 2;

Fig. 2 is a top plan view in which certain parts of the furnace roof are broken away (line 2--2 of Fig. 1);

Fig. 3 is a fragmentary View showing a port and gate at one side of the outer end of a rabble arm so that when the rabble arm is to be removed, the adjacent door is opened, the arm may be lifted, moved to one side into the port, and then be withdrawn from the furnace.

Fig. e is a vertical section of a modified form of the furnace shown in Fig. l, wherein there is a central projection from the upper surface of the hearth and the material is supplied to the hearth at the side of said central projection and is discharged at the periphery of the hearth.

Fig. 5 is a fragmentary plan view partly in section, of the furnace shown in Fig. l (line 5--5 of Fig. 4);

Fig. 6 is a vertical section of a third form of furnace wherein there is a central fixed support projecting upwardly through a central opening of the rotary hearth and the material is supplied near the center of the hearth and is fed outwardly by means of the rabble arms;

Fig. 7 is a fragmentary plan View of the structure shown in Fig. 6 (line I- of Fig. 6); and

Fig. 8 is a fragmentary view showing a modified form of the structure shown at the lower right in Fig. l.

Referring to the drawings, there is illustrated in Figs. 1, 2 and 3 a furnace I0 having a peripheral wall II of generally cylindrical form and a top I2 having a central opening I3 through which gases from the furnace are discharged upwardly through a duct isi. Said top is relatively low to assure contact to the hot gases with the material on a revolving hearth i5. Peripheral wall I I may be formed entirely of refractory material or may be made mainly of other material and lined with refractory material. Insulating material may be placed at the outside of said wall II and this insulating material may be enclosed by a casing i of metal, brick or other suitable material. The rotary hearth i5 has at its center a discharge duct It, preferably conical in shape from which the treated material may pass downwardly into a stationary discharge duct Il through a gas seal i8 including a downwardly extending flange I9 carried by the discharge duct I5 and a channel 2t secured to the top of the stationary duct Il'. Said channel 2c contains ashes or other suitable material into which said flange I9 projects.

Projecting inwardly from the wall I I are rabble arms 2i which extend to the periphery of the discharge duct Il. Each of these rabble arms 2I is provided with blades 22 so inclined that as the hearth I5 rotates in clockwise direction (Fig. 2), material fed to the outer edge of the rotary hearth through a duct 23 in the side Wall II, will be rabbled from the outer edge of the rotary hearth to the central discharge duct I 5. Obviously the inlet duct 23 might be replaced by a 4 duct passing through said roof I2. The flow of material through the duct 23 is controlled by a valve 24.

The outer end of each rabble arm extends through an opening in the wall I I and preferably is connected just outside the wall to an upright post 25 supported .by the base 26 of a leg 21 formed as a downward extension of wall I I of the furnacev and in turn supported by foundation 28. This arrangement relieves the wall Ill of the strain of supporting a heavy rabble arm entirely by connection with its outer end.

To provide such support for an arm 2| there is fixed on the post 25 a member 2g which has a semi-circular seat 3i) into which the reduced and rounded outer end of the rabble arm 2| nts. Said outer end of the rabble arm may be held in said semi-circular seat or recess 39 by means of an additional member or clamp 3i having a semicircular recess 31a receiving the opposite side of the rabble arrn from that engaged by the member 29, the two parts being clamped together by any suitable means such as bolts (not shown) At one side of the holding means for the outer end of the rabble arm there is a port comprising a doorway 32 to facilitate the insertion or removal of a rabble arm. This doorway is normally covered by a door 33 on hinges 35i and norarm. When there is a rabble arm in position adjacent said doorway and the furnace is in use, it is.

important to close the opening through the furnace wall at that point. A special piece of refractory material may be used for this purpose. When a rabble arm is to be removed, the special piece must be removed to enable sidewise movement of the arm to the adjacent special furnace door.

For cooling purposes, each rabble arm 2l is hollow and is divided into two parallel ducts by a partition 3,8 (Fig. 3) whose inner end is spaced from the inner end of the hollow portion of the rabble arm so that air or other cooling fluids may be passed into the rabble arm at one side of said partition and out of the arm at the opposite side of said partion. Cooling air may be supplied under pressure to each rabble arm ZI from a supply duct or pipe 39 extending around the furnace and after passing through the rabble arm with consequent rise in temperature may be discharged into a discharge duct or pipe di) extending around the furnace.

The supply duct 39 is connected to the rabble arm at one side of the partition 38 by means of a pipe section lli having a valve 42 therein, a'

flexible pipe section 43 and a pipe section d4 detachably connected to the rabble arm in any suit- In order to remove a rabble arm 2I from the furnace, the valves i2 and d6 may be closed' and the pipe sections M, and flV detached from the arm and then moved to' one side as permitted by the flexible pipe sections 43 and YM. will expose the end of the rabble arm 2l asshown in Fig. 3. Then the rabble arm may be engaged .by a suitable lifting device (not shown) having This fingers to insert into the passages on opposite sides of partition 38. Then after removing the sealing material in the extension of the door frame 32, opening the door 33, and removing the clamp member tI, the rabble armniay be lifted from its seat on member 29, shifted over into said doorway and then drawn out of the furnace. During this removal and substitution of another rabble arm, there will be a draft action and also generation of pressure to offset the draft effect. Consequently the furnace action will remain substantially the same as usual. The furnace will of course be provided with burners 59.

The hearth I5 comprises an upper part of refractory material supported by a metal frame 5I having a downwardly extending tubular part 52 resting upon ball bearings 53 carried by a cylindrical member 53 supported by said foundation 28. The upper ring t of said ball bearing 53 is formed like a worm gear and may be operated by a worm Ezi to turn the hearth I5.

, At its circumference the hearth I is provided with an upwardly extending rib 5% which lies beneath a downwardly facing shoulder 5l' of the inner face of the peripheral wall II. This arrangement tends to prevent material from the inlet duct 23 from escaping over the circumferential edge of the hearth. Flow of gases around the edge of the hearth is guarded against by a gas seal 58 comprising a trough 5s at the inner face of the wall II and a flange til projecting downwardly from the outer edge of the hearth into suitable material in the trough, such as sand, ashes, or any material escaping from the interior of the furnace over the edge of ie hearth. The feature of supporting the trough 59 on the wall i I at the inner face thereof enables the use of a wider trough 59 than could be used if the trough were fixed to the outer edge of the revolving hearth, unless of course the clearance between the edge of the revolving hearth I5 and the wall I I were increased as by reducing the radius of the revolving hearth.

The fiat arch top I2 of the furnace may be reinforced or supported in any suitable or well known manner.

In the apparatus of Figs. l, 2 and 3, the flow of the material is concurrent with that of the gases and the temperatures of the burning gases decrease and of the material increase toward the L.,

outlet.

A second embodiment of the invention is illustrated in Figs. 4 and 5. The surrounding wall Ila, the rabble arms 2id, the rabble arm supports and connections are substantially the same as the corresponding parts of Figs. 1, 2 and 3.

However, the hearth Iba turns in the opposite direction, that is counterclockwise and the treated material is discharged at the outer edge or circumference of the hearth. Consequently the material to be treated is supplied through a duct 23a close to the gas discharge duct #la at the center of furnace top I2. The ow of material through supply duct 23a is regulated by a valve 24a.

In this form of apparatus the hearth Isa is provided with a central upward projection Ea to restrain the flow of hot gases to the gas outlet and to prevent material falling from the duct 23a from collecting on a central portion of the top of the hearth ld where it could not be reached by the rabble arms. Preferably said central projection Ilia is of frusto-conical shape. In this form the now of the material is countercurrent to that of the burning gases.

lil

There is of course no attemptto prevent dis` charge of material yover the vouter edge of the hearth but there is a gas seal 58a comprising a flange 50a extending downwardly from the edge of the hearth into a trough 59a carried by the wall Il of the furnace and normally containing overflow material. Thel material is discharged at one sidey of the furnace through a duct lla. The flange Gila is preferably provided with a fin vfila to level off the material in the trough. In this form of apparatus, the support of the trough 59a from the wall I Ia, is particularly advantageous because material in the trough 59a can be discharged directly from the trough 5ta into the fixed duct I'Ia and maintain a minimum level ofmaterial in the peripheral running seal. Figure.

5 showsone rabble armpositioned directly in line with the discharge duct Ila and the rabble tooth or deiiector adjacent to the peripheral wall on this arm would be positioned to discharge the material from the peripheral discharge area `of the hearth directly to duct I'Ia. This arrangement minimizes the amount of material which might otherwise accumulate in the seal irte and facilitates withdrawing the material from the hearth directly to the discharge chute Vthus eliminating possibility of the material changing by the slow cooling it would receive if it first dropped into trough 59a. This design hearth also eliminates the necessity for a peripheral rib such as 5S shown in Figure 1. This contributes to a more durable furnace as such a rib is susceptible to frequent damage by use.

A third embodiment of `the invention is illustrated in Figs. 6 and 7. The hearth Ib is an*- nular and has an upwardly projecting rim I5c around its central opening. The central opening is occupied by circular head IBC of a stationary pier Ib and said head E60 has a top 56d overhanging said rim Ic and serving to support the inner ends of arms 2lb which are longer than the arms 2m of Fig. 4. The annular opening between the bottom of head ISCv and the inner surface of the central opening of hearth Ib is closed by a suitable seal ISb.

The hearth IED is rotated by substantially the same means as the hearths I5 and Isa of the other two forms.

Fig. 8 illustrates the manner in which a peripheral wall IIe can be supported on brackets 25d on posts 25o. for easy access to a gas seal 59e comprising an outwardly facing trough 59d attached to the outer edge of hearth I'd and a flange ild projecting downwardly from wall lid. This form of support and the corresponding seal may be applied to the furnace of Figs. 1, 2 and 3.

It will be evident that the various embodi ments of the invention, disclosed herein, have many important novel features. Of particular importance are the common features of using rabble arms extending inwardly from the pe-' ripheral wall, arrangements whereby said rabble armsmay readily be removed and inserted, and connections between said rabble arms and air supply and air discharge ducts or manifolds, including shut-off valves adjacent the manifolds and detachable connections with the rabble arms.

It should be understood that various changes can be made and that various features can be used without others, without departing from the true scope and spirit of the invention.

What is claimed is:

1. A. furnace comprising a peripheral wall, a

. bottom in the form of a rotary hearth, a gas seal This arrangement providesbetween the edge of the hearth and said Wall, a fixed roof having a central gas outlet, a fixed material inlet to supply and distribute material to an outer annular area of said hearth, burners directed inwardly through said peripheral wall, inwardly projecting fluid-cooled rabble arms to move material on said hearth inwardly toward the center thereof, a central outlet in said hearth to receive said material rabbled toward said center and comprising anlupper conical portion terminating in a vertical discharge pipe, a stationary pipe beneath said discharge pipe and coaxial therewith, and a gas seal between said discharge pipe and said vertical pipe and supporting means for said rotary hearth comprising an upper supporting tube coaxial with said central outlet and extending downwardly from said hearth, a foundation having a central opening around said vertical pipe, a lower supporting tube mounted on said foundation around said central opening therein, and a friction-reducing bearing between said upper and lower supporting tubes.

2. A furnace comprising a peripheral wall, a nxed roof having a central gas outlet, a rotary hearth, hearth-rotating means, burners directed inwardly through said peripheral wall, an annular trough carried by said peripheral wall and projecting beneath the edge of said hearth. a flange extending from the edge of said hearth into said trough to enter ne material therein and effect a gas seal, an outlet through said peripheral wall at the edge of said hearth, an outlet in the outer wall of said trough in register with the outlet in said peripheral wall, a blade projecting outwardly from said iiange into said trough to level the ne material and carry the excess around to said outlet, inwardly projecting stationary radial fluid-cooled rabble arms to work material on said hearth outwardly to fall into said outlet in said peripheral wall, and means to feed and distribute material to said hearth within the range of action of the inner ends of said rabble arms.

3. A furnace according to claim 2 wherein the range of action of the inner ends of said rabble arms is limited by a frusto-conical dead man mounted on said hearth under the central gas outlet in said roof and the means to feed material to said hearth comprises a duct emptying into said furnace through the roof just to one annular discharge area. a xed inlet to distribute material to said receiving area, a top with a central gas outlet, a gas seal at the edge of said rotary hearth, an outlet over said gas seal and through said peripheral wall, a central opening in said hearth, a round member in said central opening, a gas seal between said round member and said hearth, a cap on said member extending over said hearth around said opening, and fluid cooled rabbling arms projecting inwardly from said peripheral wall and with their inner ends` resting on said cap.

5. A continuous rabble furnace comprisingv a circular peripheral Wall, an enclosing roof having a gas outlet, a circular rotary hearth serving asv the furnace bottom having an annular receiving area and an annular discharge area, a xed inlet to supply and distribute material to said receiving area. a stationary rabble arm assembly projecting inwardly from outside said peripheral wall" and carrying rabbles to move the material radially on said hearth from said receiving area to said discharge area, a xed material outlet and a fixed deflector to move said material from said discharge area to said material outlet, means outside said peripheral wall for detachably supporting said rabble arm assembly, a passageway through said peripheral wall to accommodate said rabble arm and facilitate withdrawing and replacing said rabble arm assembly from Without said furnace, and separate means for closing the remaining passageway.

6. A continuous rabble furnace according to claim 5 including a running seal between said annular discharge area and said fixed material outlet to diminish air infiltration and escaping material.

7. A continuous rabble furnace according to claim 5 including a running seal between said peripheral wall and the correlative extremity of said hearth to reduce air infiltration.

8. A continuous rabble furnace according to claim 5 wherein said rabble arm is cooled by circulating cooling fluid through internal duct passages thereof communicating with cooling fluid supply and discharge ducts by detachable con-V necting joints provided at the outer end of said rabble arm.

9. A' continuous rabble furnace comprising a circular peripheral wall, an enclosing roof having a central gas outlet, a circular rotary hearth serving as the furnace bottom and having an outer annular receiving area and a central discharge port, a fixed inlet to supply and distribute material to said receiving area, a stationary rabble arm assembly projecting inwardly from outside said peripheral wall and carrying rabbles to move the material radially on said hearth from said receiving area to said discharge port, means outside said peripheral wall for detachably supporting said rabble arm assembly, a passageway through said peripheral wallvto accommodate said rabble arm and facilitate withdrawingl and replacing said rabble arm assembly from Without said furnace, and separate means fori culating cooling fluid through internal duct passages thereof communicating with cooling fluid supply and discharge ducts by detachable con` nesting joints provided at the outer end of said rabble arm.

l2. A continuous rabble furnace comprising aA circular peripheral Wall, an enclosing roof having a gas outlet, a circular rotary hearth serving as the furnace bottom having an inner annular receiving area and an outer annular discharging area, a fixed inlet to supply and distribute material to said receiving area,'a stationary rabble' arm assembly projecting inwardly from the out-f side peripheral wall and carrying rabbles to move the material radially on said hearth from said' receiving area to said discharge area, a fixed material outlet and a fixed deflector to move said material from said discharge area to said material outlet, means outside said peripheral wall for detachably supporting said rabble arm assembly, a passageway through said peripheral walll to accommodate said rabble arm and facilitatey withdrawing and replacing said rabble armassembly from without said furnace, and separate means for closing the remaining passageway.

13. A continuous rabble furnace according to 'claim 12 including a running seal between said peripheral wall and the correlative extremity of said hearth, and means to continuously maintain a minimum level of material in said running seal. 14. A continuous rabble furnace according to claim 12 wherein said rabble arm is cooled by circulating cooling fluid through internal duct 10 Number passages thereof communicating with cooling fluid supply and discharge ducts by detachable connecting joints provided at the outer end of said rabble arm.

References cited in the fue of this patent UNITED STATES PATENTS Nlunber Number Name Date 655,418 Schorr Aug. 7, 1900 1,465,417 Call et al Aug. 21, 1923 1,674,919 Pike June 26, 1928 2,332,387 Martin Oct. 19, 1943 2,471,882 Martin May 31, 1949 2,472,497 Stookey June 7, 1949 FOREIGN PATENTS Country Date 600,554 Germany July 25, 1934 15 naces, vol. II, second edition, copyright 1942, published by John Wiley and Sons, New York, New York.

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