US1867772A - Recuperative counterflow furnace - Google Patents

Description

July 19, 1932.

- E; SMALLEY RECUPERATIVE GOUNTERFLOW FURNACE 7 Sheets-Sheet 1 Filed June 5, 1929 J.E l

INVENTOR. Q0 dmaae/gg Jul 19, 1932; E. 1.. SMALLEY RECUPERATIVE COUNTERFLOW FURNACE Filed June 5, 1929 7 Sheets-Sheet 2 INVENTOR. SAMMLW 52 cy/wwafifizy,

' ATTOR EY July 19, 1932- E. L. sMALLEY" 1,867,772

RECUPERATIVE COUNTERFLOW FURNACE Filed June 5, 1929 7 Sheets-Sheet 3 ATTORNEY July 19, 1932. E, L, MALLEY 1,867,772

RECUPERATIVE COUNTERFLOW FURNACE Filed June 5, 1929 v '7 Sheets -Sheet 5 9 V a 994 3. 38 M;

- Qj ATTORNE July 19, 1932, E. LSMALLEY. 1,867,772 7 RECUPERATIVE CCUNTERFLOW FURNACE Filed Jude 5, 1929 7 Sheets-Sheet 6 II Em 5 I \l l L 2 w INVENTOR. I

BY d' vx ATTORNEY July 19, 1932. SMALLEY 1,867,772

RECUPERATIVE COUNTERFLOW FURNACE Filed June 5, 1929 7 Sheets-Sheet 7 INVENTOR.

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W mlzy I I E .70 SOURCZ'OF POM/1? Patented July 19, 1932 UNITED STATES PATENT oral-ca p EDWIN I. SMALLEY, F WHITEFISE BAY, WiSCONSIN, ASSIGNOB '10 HEVI DUTY ELEC- TRIC COMPANY, OF MILWAUKEE, WISCONSIN, A CORPORATION OF WISCONSIN BEOUPEBATIVE COUNTERFLOW FUENACE' Application filed June 5, 1929. Serial No. 868,846. I

v provide a construction of recuperative counter-flow furnace in which minimum floor area is necessary for the installation of the furnace for the heat treatment of materials.

Another object of my invention is to prom) vide a furnace structure in which the temperature of the articles or material to be heat treated may be uniformly raised by a preheating process, the article or material then subjected to a uniform heat treatment tem- E5 perature and thereafter the articles or material reduced in temperature at rate. I

Still another object of my invention is to provide a construction of heat treatment fura uniform nace with parts arranged to control the di rection of convection heat currents for the preheating, heat treatment and temperature reducing processes to which the material or article being passed? through the furnace may be subjected.

A further object of my invention is to provide a construction of recuperative counterflow furnace in which means are provided for moving articles through the furnace with antomatic means at one end of the furnace for imparting moving forces to the moving syster by which the articles are carried and means at the other end of the furnace for removing articles therefrom to allow the entry of articles to be subjected to heat treatment.

- A still further object of my invention is to provide a construction of recuperative counter-flow furnace having means for shifting material subjected to heat treatment from one chamber to another for the horizontal movement of the material through the chamber during the course of preheating, heat treatment and cooling processes.

Another object of my invention'is to provide a combined system of heat treatment and cooling chamber in a recuperative counterflow furnace system with means for controlling the passage of material through the chambers operating to mechanically shift material from one chamber to another during the process of heat treatment.

Still another object of my invention is to provide a'combined system of heat treatment and cooling chambers in a furnace where special means are provided for distributin the cooling currents which circulate throug the cooling chambers, in directions where the convection currents may be controlled to effect maximum cooling while maintaining temperature uniformity of the successive 'parts of the charges as they move through the cooling chambers.

A further object of my invention is to provide a mechanical system for loading a preheating chamber of the recu erative counterfiow furnace atone end w ile removing a.

charge in timed relation thereto at the opposite end of the furnace.

' Other and further objects of my invention reside in the construction of a recuperative counter-flow furnace of a type 1n whlch an elevator is employed for vertically shifting; a charge from one portion of the furnace to another portion thereof during the heat treatment process, as will be more fully pointed out in the specification hereinafter following by reference to the accompanying drawings, in which:

Figures 1 and 1a show a longitudinal section taken centrally through a recuperative counterflow furnace embodying the principles of my invention and showing the combined arrangement of the preheating, heat treatment and cooling chambers; Fig. 2 is a lateral cross-sectional view taken on line 22 through the cooling chambers of the recu erative counter-flow furnace illustrated n Fig. 1; Fig. 3 is a lateral cross-sectional view takenthrough the heat treatment chambers of the recuperative counterflow furnace on line 33 of Fig. 1a; Fig. 4 is a horizontal cross-sectional view through the recuperative counter-flow furnace taken on line 4-4 of preheat treatment chambers; Fig. 6 is a plan view of one of the trays which I provide for construction of the furnace illustrated on line 88 of Fig. 7 Fig. 9 is a cross-sectional view taken on line 99 of Fig. 7 showing the arrangement of the heat treatment chambers in the horizontal type of recuperative counter-flow fur11ace; Fig. 10 is a longitudinal cross-sectional view taken through the horizontal type of recuperative counter-flow furnace on line 1010 of Fig. 8; Fig. 11 is a plan view of the floor plate in the cooling and preheating chambers of the recuperative counter-flow furnace construction illustrated in Figs. 7-10; and Fig. 12 is a diagrammatic view explaining one manner of movin charges through the furnaces.

Referring to the drawings in detail, the furnace s stem of my invention'comprises a multiplicity of chambers disposed adjacent each other, one of the chambers comprising a preheating chamber, the next succeeding pair of chambers having heat treatment means therein, and the final chamber comprising a cooling chamber. In one form of my invention the chambers are aligned vertically one above another, while in a modified form of furnace the chambers are arranged in the same hor zontal plane one adjacent the other.

In Figs. 1a, 2, 3, and 4,- reference character 1 designates an upper heating chamber and numeral 2 designates a lower heating chamber which may be heated by fuel, or by electrical heating elements 8 as shown. Numeral 3 designates a preheating chamber located above cooling'chamber 4. All of the chambers are formed by walls 5 of any suitable material such as fire brick, surrounded by any suitable heat insulating material 6,

enclosed in furnace shell 7 supported by any suitable structure such as eye beams 9. Reference character 10 shows a vertically operated door opening upwardly in the direction indicated by arrow, and numeral 11 shows a door opening downwardly as indicated by the adjacent arrow. Reference character 12 indicates an elevator shaft in which is operated the elevator 13 which is used for conveying the charge from the upper to .the lower chamber, as will be hereinafter explained. Elevator 13 is provided with guide wheels 14 supported by yokes 15 with the guide wheels operating in channel shaped runways 16 at the opposite sides of the shaft (Fig. 4). Extending throughout the upper and lower tiers are rails 17 supported on the upper level in chamber 3 by means of double flanged lintels 18, the lintels being supported by lugs 18a in the opposite side walls of the furnace. Reference character 19 represents the charge conveying means in the form of trays. Rails 17 may have openings 17?; therein for the purpose of reduc ing the weight of the rails and to provide ports for circulating heated air, as hereinafter described. On the top of downwardly movable door 11 is preferably mounted ashort length of rail section 17 a so that when the door is in its lowered position, the top of such rail 17a comes in alignment with rails in the bottom chamber 4.

In operation the charge consisting of a continuous succession of trays, boxes or the like progresses through chambers 3 and 1, in the direction indicated by arrows 20, where successive portions of the charge are received intermittently by elevator 13, and lowered to the dotted outline position 35, and then progresses through the chambers 2 and 4 in a direction indicated by arrows 21. At the charging end 22 represents a mechanically operated plunger or pusher similar to 23. Pusher 23 at the heat treatment chamber end of the furnace is actuated through pinion or gear 25 engaging rack 24 on the plunger 23 which rolls on double flanged wheels 23a. 26 designates a gear transformer driven through gear 27 and pinion from suitable power means such as reversible motor 28.

The elevator is operated through suitable means such as rod 29 connected to rope 30, the rope 30 extending over suitable sheaves for insuring vertical movement of the elevator. Reference character 31 designates a reversible motor driving pinion 31a engaging gear 32, which actuates gear reducer 34 and driving pulley 33 which is a rope drum carrying rope 30 for controlling the movement of the elevator.

Reference character 36 designates a suitable structural steel frame work containing unloading and loading positions for charges. On the platform 7 O which serves as a loading platform I may provide suitable apparatus for carrying out the loading process, which apparatus I have represented more clearly in Fig. 12 as comprising the pusher 22 op erated by gear 71 which drives rack 72, which rolls on double flanged wheels 7 2a. The gear 71 is driven through suitable reduction mechanism by reversible motor 73 geared to the reduction mechanism as represented at '74. Motor 73 is connected to a source of power through line circuit 75 with a control switch 76 in the line circuit for starting and stopping the motor 73. Connected in parallel with motor 73 I provide line circuit 77 extending to the terminals 66 and 67 of winding 69a Comprising the solenoid system which nae-7,779

7 controls the operation of plunger 60. Plunger projects through the rear wall of the furnace immediately adjacent the loading position for elevator 13. A suitable bearing 61 is provided in the walls of the furnace to enable plunger 60 to slide axially under control of a toggle joint formed by members 62 and 63. The toggle member 62 is attached at one end to the plunger 60 and the toggle member 63 is attached at the opposite end to a suitable support such as bracket 64. The toggle arms 62 and 63 are mutually connected through pivotal means, and at the pivotal connection a connection is taken to solenoid 65 which is controlled by winding 69a. A suitable counterweight 65a may be provided to maintain the solenoid 65 in its lower position with plunger 60 moved out of contact with the elevator platform 13.

When the solenoid winding 69a is energized simultaneously with the starting of drive motor 73 by closing switch 76, solenoid 65 is drawn upwardly projecting plunger 60 horizontally, forcing the elevator platform 13 to the left, enabling the elevator platform 13 to engage the abutment 69 for maintaining the elevator platform in loading position while receiving a tray 19 from the heat treatment chamber. Because of the heated conditions under which elevator 13 operates there is preferably sufficient clearance between guide wheels 14 and the sides of lugs 15 and guides 16 to give suflicient freedom of movement to the elevator when the pusher 60 tends to swing the elevator to one,side.

When the plunger 22 at theloading end of the furnace has completed its forward act1o n 1n moving one tray into the furnace the driving motor 73 is stopped and simultaneously the winding 69a is deenergized. The toggles 62 and 63 thereby resume their downward positions and cause awithdrawal of pusher 60 which is facilitated by the grav'itational forces of counterweight 65a. This permits elevator platform 13 to swing clear of abutment 69 and allows the lowering of the loaded tray to the dotted line position 35 for the subsequent operation of the pusher 23' and the movement of a loaded tray into the heat treatment chamber 2, while a similar tray is being removed through the end of the cooling chamber 4 to a position on unloading platform 78. It will be seen that a tray is removed at one end of the first heat treatment chamber at thesame time that a tray is moved into the preheating chamber 3.

The entire system of successive operations may be interlocked by limit switches which may be closed as the elevator 13 reaches its upper limit or receiving position. Whilethe elevator is in intermediate positions the circuits may be arranged to prevent energy reaching the motor which drives pusher 22.

. Embedded in the side walls of thep'reheatmg and cooling chambers are flues 37 of any ing top ports 38 and bottom ports 39. The

flues may be formed with fire brick structure.

Reference character 40 shows the structure of hearth plate of either ceramic or metallic refractory which covers flues 39a with the plate preferably having graduated widths of slots 42 as shown in Fig. 5.-

In Fig. 6 I have shown a suitable tray 19 having graduated slots 43. In one form of tray, lugs 44 are provided, these lugs abutting each other end to end and separating the trays and thus forming air passageways. On the bottom of trays are guided lugs 46 for keeping the trays in alignment in their travel through the furnace.

I have found many advantages in preheating conditions by locating the ingoing work immediately above the hot outgoing work. Without return flues located in the side walls of the preheating and cooling chambers, the

preheating chamber, with such air then passing downward through the flues in the side -wall and passing across transverse flues 39a where 1t ism a sense siphoned upward to repeat its cycle of convection. For the purpose of adding to the control of direction of heat flow, I preferably provide openings 42 in the floor plate as shown in Fig. 5, such floor plate being symmetrical about the center line. The openings in the floor plate thusincrease the directional flow of aircurrents.

I provide a dividing wall 396 at the lower portion of the cooling chamber 4 which helps to control an equal flow of air in flues of the same transverse plane. In the above described oycle of operation it will be understood that the flow of convection currents preheats the ingoing work to a higher tempera- .ture and at the same time extracts more heat from the outgoing work than if the flue system were not used. By locating the preheating chamber 3 immediately above the cooling chamber 4 and dividing the cooling treatment portion of the furnace into the chambers 1 and 2, which are located one above the other, I not only increase the path of heat flow and secure better distribution of convection currents through the furnace, but also conserve the area required for the installation of the furnace. w

I may, however, obtain advantageous results by employing the principles of my invention in a furnace system where the preheating, heat treatment and cooling chambers are located in horizontal alignment as shown in Figs. 7-10 wheret-he heat treatment chambers are shown side by side at 47 and 48, one

cooling chamber 50a, and all with a central longitudinal division wall 80 between. All

' chambers are enclosed by suitable walls 51 having arched construction. On the interior of heat treatment chambers 47 and 48, I mount heating elements 8 in a manner similar to the arrangement of heating elements in the furnace structure of Fig. 3, although any method of heating may be employed. The walls of the furnace 51 are of suitable fire brick and heat insulating material and a furnace shell substantially as described in connection with the structures of Figs. 1-4. Pushing mechanisms, similar to those described, and as applied in Figs. 1 and 1a may be used for progressing the charges through the furnace on trays 19, similar to the trays employed in the furnace construction heretofore described and shown in Fig. 6. The cooling chambers are connected withadjacent preheating chambersby flues- 54, which receive convection currents through ports 52 of the cooling chambers 50 and 50a and conduct such convection currents through ports 53 in the arches of preheating chambers 49 and 490., where the charges on trays 19 in preheating chambers are preheated. The convection of air currents is downward through the ports 55 of ceramic or metallic refractory plates 56 forming the support for rails 17, then along horizontal fiues 57 and upwardly through the orts or openings 55 in plates 56 in the cooling chambers 50 and 50a. 7 The ports 55 in the plate 56, as shown more clearly in Fig. 11, are graduated, with the largest openings farthest from the cooling charge, to control the direction of flow of the air or gases. The convection currents,

shown by arrows in Fig. 9, are guided by ports 52, flue 54, ports 53, ports 55 and flue 57, in such manner as to fully distribute the cooling influence of the air on the charges in the cooling chambers 50 and 5011 while preheating the charges introduced in preheating chambers 49 and 49a. The paths of movements in reverse direction of the two charges passing through the furnace have been shown by arrows 59 and 59a, where each charge is gradually progressed through a preheating chamber to the heat treatment 1c)hamber, and then through a cooling cham- In tests to determine the efiicienc of the recuperative counter fiow furnace o my invention, I have compared results obtained both with and without flues interconnecting the preheating and cooling chambers. In an investigation conducted upon a furnace of the superimposed chamber type, two tests were run with the same weight of material heated to 1200"E, one test being conducted with the preheating and cooling chambers superimposed but without interconnecting lines and another test being conducted with the preheating and cooling chambers su erimposed and with the interconnecting ues. Without fiues a time interval of sixty minutes was required for the temperature in the preheating charge to start downward in temperature. That is to say, without the side wall flues, a whole hour was required for the temperature to start down in the preheating cycle. Under the same furnace conditions but with side wall flues interconnecting the preheating and cooling chambers, forty percent more temperature was obtained in the preheating charge in thirty-two and one-half minutes. The importance of arranging the flues between the preheating and cooling chambers can therefore be fully appreciated.

While I have described preferred embodiments of my invention, I desire that it be understood that modifications-may be made and that no limitations upon my invention are intended other than are imposed by the scope of the appended claims.

What I claim as new and desire to secure by Letters Patent of the United States is as follows:

1. In a recuperative coimter-fiow furnace, a multiplicity of chambers disposed in horizontal rows in superimposed relation, means for passing articles of a charge under heat treatment through said chambers for subjecting the articles to a process of heat treatment in certain of said chambers, while preheating and cooling others of said articles in other chambers adjacent to the heat treatment chambers, and flues interconnecting said cooling and preheating chambers in superimposed relation for establishing directed convection air currents through said cooling andpreheating chambers.

2. In a recuperative counter-flow furnace, a multiplicity of furnace chambers arranged inrows, one of the rows being superimposed on the other row, one of said chambers in the upper row being arranged to receive articles and subject the same to a process of preheating, a pair of superimposed and ad acent chambers being arranged to subject articles to a process of heat treatment, and another of said chambers immediately below said up-' per one of said chambers being positioned for reducing the temperature of articles from said heat treatment chambers, and means for subjecting the articles in said temperature reducing chamber and said preheating chamber to the effect of directed convection currents.

3. In a recuperative counter-flow furnace, a plurality of chambers comprising preheating, heating and cooling chambers, disposed in rows, one of said rows being superimposed on the other row and operating cyclically in a eanna cooling chambers, flues interconnecting said reheating chamber with said coollng' chamber for establishing directed convection air currents therebetween and through said perforated horizontal partition for reducing the temperature of charges subsequent to a heat treatment process and raisin the temperature of charges prior toa eat treatment process in the course of the passage of charges through said furnace.

4. In a recuperative counter-flow furnace, a multiplicity of separate chambers interconnected one with the other and disposed in rows, one of said rows being superimposed on the other row, heat treatment means disposed in selected chambers, a preheating chamber connected to one of said selected chambers, a cooling chamber immediately below said preheating chamber and connected with another of said selected chambers, and means for moving articles to be subjected to heat treatment through said chambers.

' 5. In a recuperative counter-flow furnace, a multiplicity of furnace chambers disposed adjacent each other in rows, one of said rows being superimposed on another row, selected chambers being rovided with heat treatment means, a pre eating chamber connected with one end of one of said selected chambers a cooling chamber connected with the end of another of said chambers containing heat treatment means, means for moving material to be subjected to heat treatment through all of said chambers, and means interconnecting adjacent ends of said selected chambers.

6. In a recuperative counter-flow furnace, a plurality. of chambers disposed adjacent each otherin rows, one of said rows being superimposed onanother row whereby said chambers are disposed on different levels, an open shaft adjacent one end of said furnace interconnecting the chambers on diiferent levels, means operative in said open shaft for transferring material from one level to another level for cyclically moving said material through said furnace, a preheating and cooling chamber disposed in su erimposed relation, and means for trans erring heat convection currents between said last mentioned chambers.

7. In a recuperative counter-flow furnace, a multiplicity of separate chambers connected end to end and disposed in rows, one of; said rows being superimposed on another row, heat treatment means in selected chambers, a shaft connecting the chambers immediately over each other adjacent one end of said furnace, an elevator operative in said shaft, and means for moving material to be subjected to'heat treatment through said chambers, said elevator operating to transfer the material under heat treatment from one chamber to another,

cooling chamber disposed in superimposed relation,

and means for directing the flow a preheating and of heat convection currents between said last mentioned chambers.

8. In a recuperative counter-flow furnace, a multiplicity of chambers arranged'in rows, one of said rows being superimposed on another row, heat treatment means in said chambers at one end of said furnace, a shaft interconnecting the chambers containing said heat treatment means, an elevator operative in said shaft for transferring material between said last mentioned chambers, a preheating chamber leading to one of said aforementioned chambers, a cooling chamber extending from the other of said chambers, a horizontally extending perforatedv partition separating the preheating and cooling chambers while allowing the circulation of heat convection currents therebetween, and means for moving material through said chambers.

9. In a recuperative counter-flow furnace,

a multiplicity of chambers. adjacent each other and disposed in levels one above an other, a shaft adjacent one end of said furnace interconnecting the chambers at the different levels, heat treatment means disposed in the chambers immediately adjacent said shaft, means for circulating convection currents through the chambers remote from said shaft for setting up a cooling effect in the chamber connecting with the exit of one of the chambers containing said heat treatment means and for establishing a preheating effect in the chamber leading to the first of said chambers including said heat treatment means and an elevator operative in said shaft for transferring charges of material between said heat treatment chambers at different levels.

- 10. In a furnace, a multiplicity of chambers arranged in rows, one of said rows being superimposed on another row, a vertically movable carrier disposed adjacent one a charge therefrom, means for. inserting a charge at the opposite end of the toprow of said chambers, means simultaneously operative upon the insertion of a charge into the end of the upper row of said chambers for securing the vertically movable carrier in receiving position to receive a chargefrom the opposite end of said upper row of said chant bers, and flues connecting selected chambers for efl'ecting the transfer of heat convection row and the intake end of the lower row of the furnace, a charging device located at the end of-said rows of chambers for. receiving inlet end of the furnace, means simultaneously operative with the operation of said charging device for positioning said movable carrier adjacent the delivery end of the upper row of said furnace chambers for receiving charges in the course of movement of said charges through said furnace, and flues interconnecting selected ones of said chambers for directing the flow of heat congection currents betweensaid selected chamers. 1

12. In a furnace, a plurality of chambers ar-, ranged in rows, one of said rows being superimposed on another row, trays for supporting charges arranged to be moved through said chambers, a. movable carrier for receiving an individual tray located at the delivery end of the upper row of said furnace chambers, a charging device for inserting a tray located at the inlet end of said furnace, means for positioning said movable carrier at the delivery end of the upper row of said furnace for receiving a tray simultaneously with the insertion of a tray under control of said charging device at the inlet end of said furnace said carrier operating to transfer the charge from the delivery end of said upper row to the intake end of the lower row for delivery through the discharge end of the lower row and flues interconnecting selected ones of said chambers for directing the flow of heat gonvection currents between selected chamers.

13. In a furnace, a multiplicity of chambers divided into preheating, heat treatment and cooling chambers, said cooling and preheating chambers having a multiplicity of flues interconnecting said cooling and preheating chambers, supporting plates forming the bottom of each of said cooling and pre heating chambers, each of said supportin plates being apertured for the circulation 0% convection currents through said last mentioned chambers and through the flues 'disposed in the walls thereof, and means for progressing charges through said chambers. 14. In a furnace, a plurality ofchambers disposed in superimposed relation, means for passing material to be heat treated through said chambers, certain of said chambers being separated by a horizontally extending perforated partition and being interconnected by flues at opposite sides thereof for the circulation of air currents between said chambers and through said flues and said perforated partition, for effecting an interchange of heat between articles of the charge passin through said chambers. 15. In a furnace system, a plurality of chambers comprising preheating, heating and cooling chambers arranged in rows, one of said rows being superimposed on another row for the passage of material to be subjected to heat treatment therethrough, plate members forming the bottom for each of said preheating and cooling chambers, said plate members being apertured for the passage of convection currents therethrough, and a multiplicity of flues interconnecting said preheating and cooling chambers adjacent selected plate members for directing convection currents between said chambers and through said plate members.

16. In a furnace, a multiplicity of chambers disposed in different horizontal planes, an apertured division wall between the upper and lower chambers for the passage of convection currents therethrough, an apertured supporting plate closing the bottom of said lower chamber for the passage of convection currents therethrough, and flues interconnecting the top of the upper chamber and the bottom of the lower chamber for establishing a directional path for the circulation of convection currents between said chambers, and means for moving articles in opposite directions through the upper and lower chambers.

In testimony whereof I afiix my signature.

EDWIN L. SMALLEY.

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