US2084241A - Metallurgical furnace - Google Patents

Description

June 15, 1937. c pp 1 2,084,241

METALLURGICAL FURNACE I Filed July 3, 1955 2 Sheets-Sheet l Lhlcnam; 6 v

June 15, 1937. A. M. CAPPER 2,084,241

METALLURGICAL FURNACE Filed July '3, '1935 2 Sheets-Sheet 2 Cs 1 Cw Patented June 15, 1937 UNITED STATES PATENT OFFICE wait: Serial l Vo 29,726

This invention relates to improvements in metallurgical furnaces and more particularly to such a furnace of the bell type and which is heated by direct fire.

5 Metallurgical furnaces are used for heat treating or annealing metal sheets, coils, strips, castings and the like and there is nothing broadly new in a metallurgical furnace per se, but the 7 present invention constitutes a furnace which is 10 much improved over those such as are now known and in use. f

The particular construction and the particular features which constitute the present improvement will appear in more detailhereinafter, it being suilice to say at this time that one of the primary objects of the invention is the provision of a direct fired metallurgical furnace.

Another object of the invention is the provision of a metallurgical furnace in which the material maybe efliciently heated or treated tion is to provide a furnace of the type described in which the material to be treated can be placed in and removed from the furnace without the use of doors or cars such as has been the practice 35 in the past, and which practice is undesirable in that the heat within furnaces so loaded is not equal in all of its parts and the cost of attaining and maintaining heat within such types of furnaces is extremely great.

40 Another and further and important object of the invention is the provision of 'an improved furnace wherein silicon plates may be successfullytreated;

Other specific objects, novel features of con- 4 struction and improved results will app ar in the line 66 of Fig. 2 looking in the direction indicated by arrows.

Having reference now to the drawings in which like parts are designated by similar reference numerals throughout the description, I repre- 5 sents a base or hearth composed preferably of some insulating or refractory material and maybe ermanently or portably located at approximat floor level on a suitable supportsuch as beams the like. This hearth is supported 10 upon a suitable base plate 20 and is held in po-- sition thereupon by suitable angle or end members 4.

The burner chamber is formed by a portable bell designated as an entirety by A and is made 15 up of side walls, end walls and a cover or top.

These walls and top are composed of insulating or refractory material and supported and constructed within a suitable metallic frame II which at its upper endis provided with a plurality 0 of suitable eye bolts 1'4 by means of which the cover can be lifted from the hearth by a hoist or the like, thus enabling the furnace chamber to be loaded and unloaded.

Centrally and longitudinally disposed at the under side of the hearth and its supporting plate there is positioned a duct or channelway I which communicates with a plurality of exhaust outlet flues 8 arranged in longitudinal separated alignment of the hearth. This flue outlet passage 1 is provided with a communicating stack 9 for conveying the products of combustion outwardly to atmosphere from the building in 'which the furnace is located.

For the purpose of guiding and partly positionmg the cover A onto the hearth the front and rearwalls of the cover are provided adjacent their lower edges with eyes or loops l4 which are adapted to receive suitable vertically extend-' ing pins l3 mounted upon the base. 40

In using the furnace the material to be treated is usually and preferably placed upon a suitable tray l5 which is supported in separated relationship to the hearth by balls l6 andthe material is then covered with a suitable box 14, commonly referred to as an annealing box. When the material to be treated is so positioned within the furnace the cover A is of course lowered' and the fuel is turned on to the burners and ignited.

Although I have -describedthe material to be treated as being contained within a cover or annealing box lHt is to be understood that the use of this box is not absolutely essential and that 5 This particular furnace has been conceived for the treatment of silicon plates. The general use to which silicon plates are put is such as to make it necessary that they be absolutely flat when treatment of them is completed. These plates must not have any wrinkles or bends in them. If silicon plates are not subjected to practically an absolutely -even heat treatment wavy or crinkled plates result and it is therefore to overcome this undesirable result that this particular type of furnace has been conceived.

The burners are arranged at 28 and 29 in the side walls of the cover as is illustrated in Figure 2 of the drawings and the combustible mixture passes into the burner chamber 24 through the openings 30 and 3|.

To prevent direct impingement of flame against the side walls of the annealing box, which would result in an uneven heating of the silicon plates with the heretofore explained undesirable results, a baflle is positioned between the burner outlet openings 30 and 3| and the side walls of the annealing box. This baiiie is in the form of a U shaped member having a side wall 32 and end walls 33,which abut the side walls of the box I! with the result that the products of combustion travel upwardly along the outer face of the shield or baflle as indicated by arrows in Figure 2 of the drawings, and the products ofcombustion will pass downwardly through the open tops 34 of the shields and along the side walls of the annealing box and under the box into the outlet flue I, all of which is clearly indicated by arrows.

Thus it will be seen that the furnace chamber is heated by direct fire.. This type of heatingcan be called luminous and has been found to be highly eflicient for obtaining the results desired.

As the gas and air pass into the furnace chamber the carbon within'the mixture is progressively freed which tends to cause an even temperature and distribution of heat throughout the entire furnace chamber.

The construction just described is such that in actual use it has been found that even with a direct fired furnace even and smooth heat distribution has been sufficiently well obtained as to permit successful treatment of silicon plates.

- It is of course to be understood that the furnace need not be constructed in every detail exactly as described and that departures could be made.without departing from the spirit of the invention.

By the combination of a bell type furnace heated by directfire several advantages are obtained and several disadvantages of furnaces as now known and used are obviated.

Furnaces as now in common use in most instances are charged with the material to be treated through doors or the like and the material to be treated is, in the majority of instances,

transported in cars or similar conveyances. The doors in themselves are objectionable in that there is of necessity certain air or atmospheric leakage around them thus making it diflicult and expensive, to maintain the heat evenly at the desired temperature and additionally these doors inherently tend to make that end or side of the furnace where they are located cooler than the remaining part of the furnace chamber due to radiation from the doors themselves.

In addition to this disadvantage furnaces of the particular type being now discussed are also more costly to build, operate and maintain by reason of the additional necessary equipment and the upkeep of that equipment, it being quite evident that in a furnace of my type the load can be charged or placed in the furnace chamber with the minimum equipment.

By heating the furnace chamber by a direct flre and introducing the combustible mixture in the specific manner or a manner equivalent to I that heretofore described I obtain the advantage of a complete permeation of the atmosphere within the furnace chamber of a free carbon which acts as a medium of heat transference to the work being treated. This is true irrespective of whether or not an annealing box is used as a cover for the work.

I am aware that in the past metallurgical furnaces have been constructed and patented wherein heat transference tubes and similar devices have been used within the furnace chamber as the heating medium. These devices are objectionable not only because of their excessive primary cost but because of their high maintenance cost due to necessary replacement of the heating tubes or the other particular heating elements utilized within the heating chamber of the furnace. My device constitutes a vast improvement over devices of this nature.

I claim:

1. In a metallurgical furnace, a hearth, a cover for said hearth for forming a closed furnace chamber, a series of flue outlet openings centrally arranged in said hearth and having communication with an outlet stack, a closed box for containing the material to be treated within the furnace, means supporting said box above said hearth bottom and the outlet flue openings thereof, vertically extending bafiles paralleling each side of the box and the side walls of the furnace cover, said bailles provided with end walls extending towards and engaging the side walls of the box at a point adjacent the box ends, the upper ends of said baflles terminating in approximately the same horizontal plane as the top of said box and forming between themselves-and the box closed flue passageways, burners in the furnace chamber, for the purpose described.

2. In a metallurgical furnace, a hearth, a cover for said hearth for forming .a closed furnace chamber, a closed box centrally supported within said chamber and above the'hearth thereof and containing the material to be treated within the furnace chamber, the side walls of said cover paralleling the side walls of the box and in separated relation therewith, a series of burners disposed in a, horizontal row adjacent the bottoms of each of said cover side walls, a second series of burners disposed in a horizontal row in each of the side walls of said cover at a point in a plane slightly below the plane of the top of said-box, a baifle at each side of said box and extending from the hearth upwardly to a point above the upper rows of burners, said baiiies paralleling the side let opening in said hearth at a point under said box, and said openings having communication walls of the cover and the side walls of the box vunder the box and outwardly from the furnace chamber through the aforementioned hearth flue outlet opening.

3. In a metallurgical furnace, a hearth, a cover for said hearth for forming a closed furnace chamber, a flue outlet opening arranged in'said hearth and having communication with an outlet stack, a support for the'sheet material to be treated within the furnace, said support being positioned above said hearth bottom and the flue outlet opening thereof, vertically extending baf-v fies paralleling each side of. the sheets and the side walls of the furnace cover and in spaced relationship to each, said baflies provided with end walls extending towards the sheets at a point adjacent their ends, the upper ends of the baflles terminating in approximately the same horizontal plane as the top-most work sheet and forming between themselves and the sheets flue passageways, burners in the opposite side walls of said furnace cover for directing flames against said baflles, and said stack and hearth flue outlet opening creating a down draft in said furnace chamber, for the purpose described.

ARTHUR M. CAPPER.

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