US1515511A - Electrically-heated furnace or leer - Google Patents

Description

1 1,515,511. E. E. MIL,NER

ELECTRICALLY HEATED FURNACE OR LEER Filed Feb. i, 1922 5 Sheets-Sheet 1 NOV- 924,

FA b INVENTOR Nov. 1924. 1.515511 E. E. MILNER -ELECTRICALL1 HEATED FURNACE OR LEER Filed Feb. 1, 1922 5 SheetaF-Shoef. 3 1 4.

29'; 29 4 21 22 5 V 1 I ['1 I! 1' l mu u u Iil I g INVENTOR Nair. l

E. E. MILNER ELECTRICALLY HEATED FURNACE 0R LEER 5 Sheets-Sheet 4 Filed Feb. 1

INVENTQR I flunk a E. E'." MILNER ELBCTRICALLY HEATED FURNACE on LEER Filed Feb 1, 1922 s Sheets-Sheet 5 5M i? flwm 4 7 1 WW Patented Nov. 11, 1924. a UNITED STATES PATENT OFFICE.

EDWIN E. MILNER, OF SCOTT TOWNSHIP, ALLEGHENY COUNTY, PENNSYLVANIA, AS- SIGNOB TO B. L. DIXON COMPANY, OF CARNEGIE, PENNSYLVANIA, A CORPORA- Q'Figure 3 1s a plan view TION OF PENNSYLVANIA.

ELECTRICALLY-HEATED FURNACE OB LEEB.

Application filed February 1, 1922. Serial in). 533,484.

To all whom it may concern:

Be it known that I, EDWIN E. MILNER, a citizen of the United States, residing in Scott Township, in the county of Allegheny, State of Pennsylvania, have invented a new and useful Improvement in Electrically Heated Furnaces or Leers, of which the following is a full, clear, and exact description.

My invention relates to furnaces or leers and "articularly to such furnaces or leers which are heated by electricity.

Heretofore attempts have been made to electrically heat furnaces or leers but such attempts have been unsuccessful commercially because of cost of installation and ineflicient heating.

I have devised means whereby the cost of the equipment is not abnormal and by which the energy supplied thereto is eflicientl transformed and the heating chamher 0 the furnace or leer is properly heated. Means are also provided by which the temperature may be controlled so as to produce suitable zones or regions in the heating chamber when such zones or regions are necessary as, for instance, in annealing leers for treatment of glass ware.

By the use of electric heat the expensive muffle construction is avoided when the furnace or leer is to be used in the treatment of lass ware or other articles which might be damaged by products of combustion.

I have used an annealing leer. to illustrate a furnace structure embodying my invention, but my invention is not limited to leers as the principles of my invention may be used in many kinds of structures.

My invention will be better understood by reading the following description taken in connection with the accompanying drawings forming a part thereof and in which,

Figure 1 is a longitudinal vertical section of an annealing leer embodying my invention;

Figure 2 is a cross-section .on the line II-II of Figure 1; 7

shown in Figure 1; a

Figure 4 is a longitudinal vertical section of a part of a leer showing a modified form of my invention;

Figure 5 is a cross-section of one-half of the leer of Figure 4 on line V-V;

Figure 6 is a vertical longitudinal section of the device j of the leer showing a further modification of my invention;

Figure 7 is a cross-section of one-half a leer shown in Figure 6 on line VIIVII; Figure 8 is a cross-section of a leer similar in construction to that shown in Figure 1, but having the heating units arranged longitudinally of the heating chamber;

Figure 9 shows a detail of construction of a reflectorand its location in the leer. This view is on a larger scale than the. other vlews; l

Figure 10 shows a diagram of the electrical circuits for the type of leer shown in Figures 1 to 8 inclusive;

Figure 11 shows .a diagram of electrical circuits of the leer as shown in Figure 8;

Figure 12 shows a detail of the supporting means for the heatin units.

Referring to the rawings, the numeral 1 designates the heating chamber. The walls of this chamber may be of any suitable and standard'construction. The side walls may be made of the brick 2, on the outside of which is placed a wall 3 of insulating material, such as kieselguhr brick or any other similar material. The roof wall of the chamberis made up of a series of reflectors 4. The reflectors may take any desired form, but those represented in the drawings are parabolic for reasons which will be given later. The reflectors 4 extend transversely across the roof of the heating chamber as shown in Figure 1 and are supported in position by key blocks 5 having the general shape of I-beams. The key blocks 5 are provided at their lower ends with flanges 6 against which the edges of the reflectors 4 rest, as shown in detail in Figure 9. The key blocks 5 are provided at their ends with vertical recesses 7 as shown in Figure 1. Hanger bolts 8 pass through these recesses and support the key blocks in place. The hanger bolts are supported by transverse channels 9 which pass over the outside of .the roof of the heating chamber. From the foregoing, it will be evident that the reflectors are supported in position by the frame work of the heatin chamber.

As will be noted rom Figure 1 the reflectors are curved so that a corrugated or reentrant surface is produced by the reflectors along the roof of the the heating chamber. The top of the roof is leveled byfilling ico in with a powder or sand 10 as shown in Figure 1. A suitable material for this is kieselguhr. This material forms a good in-- sulator on the back of the reflectors. On top of the material 10 are placed insulating brick 11, such as kieselguhr brick or other. suitable material.

The side walls of the heating chamber are held together by the usual side buck sta s '13 and tie rods 14. The end walls are he (1 together in the usual manner by the buck stays 15 and tie rods16. Longitudinal members 17 are connected to the supporting channels 9 so as to strengthen the frame structure.

The front wall of the heating chamber may be constructed or any suitable material such as fire brick. This front wall is provided with one or more openings 18 through which the material to be annealed or otherwise treated is introduced to the heating chamber. These openings are provided with anysuitable closure 19. The heating chamber is provided with any desired type of conveyor 20 for the well known purpose of conveying the material through the leer.

That portion of the heating chamber underneath the conveyor may be constructed of any desired material usually used in the construction of leers. In Figure 1 this construction is of fire brick 21 having a chamber therein filled with insulating material 22, such as kieselguhr.

Connecting with the heating chamber 1 is a tunnel 23. The tunnel 23 may be of any suitable length and construction desired. The tunnel 23 is provided with insulating layers 24, the number of which decreases in the direction away from the heating chamher. The decreasing of the thickness of the insulating material allows the tunnel to become cooler and the material is therefore gradually cooled as it is moved away from the heating chamber. This construction and action are well known to those skilled in the art.

The chamber 1 is heated by a series of electrical heating units 25, 26 and 27 which are arranged in the roof wall of the heatin chamber, one of said units being supports in operative relation to each of the reflectors 4. In the construction shown in Figure 1 a heating unit 28 is provided in the front wall and four heating units 29 are provided in the base of the heating chamber underneath the conveyor. A covering 29 of silicon carbide tile is placed over the units 29 to protect the units from bits of glass that might fall thereon from the conveyor 20. These tiles are ood heat conductors. In the structure of Figure l the heating elements do not extend down the side walls of the chamber but extend only across the roof, end wall and base of the chamber. The heating units are made up of non-conductor core 30 shown in detail in Figures 9 and 12 around which is wrapped or coiled a resistance wire 31 of any suitable material. The units are supported b the arrangement shown in Figure 12. This construction comprises a sleeve 32 which has an opening into which reduced end portions 33 of the adjacent cores 30 enter. The sleeve is provided with an extension 34 which passes through the reflector 4 and is held in place by a Washer 35 and nut 36. Any other suitable means may be used for supporting the heating units in place. The cores 30 may be of any desired length. A spacing member 37 surrounds the projection 34 and accurately spaces the sleeve 32 from the face of the reflector.

Figures 4 and 5 illustrate a modification of the invention differing from the construction of Figures 1 and 2 in that the heating units 25, 26 and 27 extend across the roof of the heating chamber and down the sides thereof. There is only one of the units 29 in the base of the heating chamber, whereas there are four in the construction of Figure 1.

The construction shown in Figures 6 and 7 differs slightly from those previously described in that this construction is provided with a heating unit 38 which extendslongitudinally of the heatin chamber along the side walls near the roo Figure 8 shows a still farther modification in which heating units 39 extend longitudinally of the heating chamber in the roof. This construction also has a heating unit 29 in the same relative position as the constructions heretofore de scribed.

Figures 10 and 11 illustrate diagrammatically the circuits of the heating units. The units are supplied from any suitable source of electrical energy, such as the generator 40. The unit 25 has an adjustable rheostat 41 in series therewith and is also provided with a switch 42.

The units 26 are connected in parallel between the busses 43 and 44. These three units have an adjustable rheostat 45 in series therewith and they are each provided with a switch 46.

Each of the units 27 is provided with an adjustable rheostat 47 and also with a switch 48.

The purpose of the foregoing arrangement of electrical circuits is to permit of accurate control of the temperature inside the heating chamber. By reason of the arrangement illustrated any one'of the units may be cut out of operation by opening the corresponding switch. The heat generated by any particular unit may also be varied by the proper adjustment of the rheostats in series with the units. The arrangement is such that the chamber 1 may be divided into zones or regions of varying temperature as is necessary in some instances in the treatment of various articles.

Figure 11 illustrates one unit used in the type of furnace shown in -Figure:8, that is to say, wherein the units extend longitudinally in the roof of the heating chambr. The units are so wound with the re sistance wire as to generate moreheat per unit of length in someportions thereofthan in others. The portion 49 has the greatest number of turns thereon and therefore generates a greater heat for a given length than the portion 50. The portion 50 generates I more heat per unit of length than does the portion 51 and the portion 51 likewise generates more heat per unit of length than does the portion 52. That is to say, the resistance wire is wound closer and closer together throughout the length of the unit from right to left as viewed in Figure 11. Connected to the'resistance wire are leads 53 and 54. These leads are'connected together by a wirefl55 in which is placed an adjustable resistance 56. These wires and leads constitute a shunt around the portion 49 of the unit. By varying the resistance 56, any desired amount of energy may be shunted around the portion 49 so as to con- I trolits temperature. The shunt circuit may be opened by moving the inter-off of the resistance, thus allowing al 'of the current to pass through the portion 49.

The portions 50, 51 and 52 are likewise provided with adjustable shunt resistances 57, 58 and 59, respectively, so that the temperature of those portions may be likewise controlled by controlling the amount of resistance in shunt therewith. Each of the units is provided with these regulating means so that they may be individually or collectively regulated so as to produce zones or regions differing in temperatures in the heating chamber. of the leer. The source of current is connected at the points marked plus and minus on Fi re 11.

In order that the heat which is emltted by the heating units may be more efficiently applied to the heating chamber, the surface of the reflectors indicatedby the heavy line 60 of Fig.9 may be glazed by any desired method or this surface may be painted or coated or otherwise treated so that it will act as a more eflicientreflector than would be the case if that surface were dull. The full lines 61 in Figure 9 illustrate the lines of direct radiation of heat. from the resistance coils in all directions and the dotted lines 62 illustrate the reflected rays coming from the reflector. By reason of the parabolic form of the reflector surface it Will be noted that the reflected lines 62 are parallel with each' other, whereas the lines of direct radiation radiate in all directions from the heating unit.- Any desired form or shape may be given to the reflect- .ing surface and the reflectors may be made of any suitable material. Due to the high temperature employed, howeyer, it will be necessary that the these reflectors be constructed of material capable of Withstanding the temperatures and any material may therefore be used which will meet this requirement.

My invention has many advantages; among which may be mentioned that the heating units are simple in construction and are placed entirely within the heating cham r so that fullefi'ect is given to the heat radiated therefrom; the units are inset in the walls of the heating chamber so that they are protected by the ridges produced by the lower ends of the key blocks 5; the inset portionsxwhich receive the units act as reflectors so that the heat emitted from the units is efliciently reflected into the heating chamber; the heating chamber is free from products. of combustion and drafts caused by such combustion; all the advantages of a 'Inuflle leeror furnace are secured with a construction which is much less expensive; means are provided for controlling the temperature of the heatingchamber so as to divide the same into zones or regions of different temperatures; heating units are provided in the base and front Wall of the heating chamber to preheat the conveyor before the articles are placed thereon; by reason of 'the simple construction of the heating units and the walls of the heating chamber, the construction of the leer is simplified andthe cost thereof much reduced; by reason of theprovision of reflecting surfaces in the Walls of the heating chamber, thereis less tendency through the walls. will be apparent to I claim: I

1. In an electric furnace, the combination of a chamber to be heated, a plurality of electrical heating elementsiin said chamber, reentrant heat reflecting surfaces in the Many other advantages those skilled in the art.

for the escape of heat Cal walls of said chamber, means for support- .7

ing one of said elements in each of said reentrant surfaces in spaced relation thereto to permit free radiation of heat from substantially the entire area of each surface, and

means for varying the effective heat in zones either transversely-or longitudinally of the,

furnace, substantially as described.

2. In an electric furnace, the combination of a chamberto be heated, a plurality of.

heat reflectors forming a part of at least one 6 means-for varyingthe said chamber, and an electric heating element supported in operative relation to each of sald reflecting surfaces, substantially as de- 'scribed.

- 5. In an electric furnace, the combination of a chamber to be heated, a plurality of inset heat reflectors arranged in continuous side-by-side relationship and constituting partof the wall of said chambenand a heating element for; each of said reflectors, substantially as described.

6. In an electric furnace, the combination of a chamber to be heated, a plurality of removable reflectors inset in the wall of said chamber and adapted to freely directheat rays into the chamber and a heatin-g'element for each of saidireflectors, substantially as described. y

7 In an electric furnace, the combination of a chamber to be heated, reflectors therein, an electric heating unit supported in heatradiating position in each of said reflectors,

means regulating the generation of heat by said units, afurnace frame, and means su porting saidrefle'ctors directly from said frame, substantially as described. 8. In an electric furnace, the combination of a chamber to be heated and a plurality of electric heating units supported in heat radiating offset portions of the walls of said chamber, and means regulating the 'generation of heat in said units to produce zones of varying temperature in said chamber, substantially as described,

9. In an electric furnace, the combination of a chamber to be heated, a pluralit of electric heating units supported in 0 set" portions of the walls of said chamber, a conveyor in .said chamber, and an independent electrical heating unit in the bottom of said chamber below the conveyor, substantially as described.

10. In an electric furnace, a to wall having a series ofkey block's, heat re ectors supported by said blocks and a heati ng element in each of said reflectors,-substantia1ly as described; I 11. In an electric. furnace, a top wall havmg a series of transversely extending key blocks, transversely extending "heat reflectors supported by said key blocks, and a heating element in each of said reflectors,

substantially as described.

12. In an electric furnace, a top wall havmg a series of key blocks, heat reflectors supported by said key blocks, a heating element in each of said reflectors, an' endless conveyor in said furnace, and an electric heating means for heating the lower'run of said conveyor, substantially as described. 13. In an electric furnace, a to wall havmg a serles of key blocks, heat re ectors supported by said key blo ks, a heating element in each of said reflectors, and means for reg.- ulating the heat generated in said elements, substantially as described.

.In testimony wherof I have hereunto set my hand.

EDWIN E. MILNER.

. Certificate of Correction.

It is hereby Count Pennsyl vania,

[SEAL.]

certified that in Letters Patent No. 1,515,511, 1924, upon the application .of Edwin E. lihliier, of Scott for an m aovemeit greq Leers, errors appear in. the-print specl ca on 1 u iemacnhg Page 4, lines 7 and 8, claim 4, strike out zvgi'gsmfafier the word of insert the said Letters that'the same may conform, to

this 26th day of May,

anted November 11, flownship, Allegheny Electrically-Heated- Furnaces or correction as follows: of said chambers and Patent should be read with these 7 the record of the case in the .KARL FENNING, Acting Commissioner 0; Patents.

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