US2474504A - Heating ingots - Google Patents

Description

c. H. WEST HEATING INGOTS June 28, 1949.

3 Sheets-Sheet 2 Filed Oct. 20, 1944 Car/H Wesf June 28, 1949. c. H. WEST 2,474,504

' HEATING INGOTS Fild Oct. 20, 1944 I 3 Sheets-Shet 3 Fig. 3.

INVENTOR {7 Car/ H Wes? Patented June 28,

Pica

HEATING mqo'rs cm fewest, St. cmmme, om, aesignor u 'Blaw-Knox Company, Pittsburgh, 2a., a eor poration. of New Jersey Application October 20, 1944, Serial No. 559,500

This invention relates to heating ingots and more particularly to imparting to ingots a uniform penetrant heat' prior to rolling the ingots in a'blooming mill. The invention further relates" recognized for many years but which have not,

heretofore been satisfactorily overcome. Among these disadvantages are the washing of ingots (the melting of scale on the ingots due to excessive heat in the heating chamber), the burning of localized portions of ingots due to hot spots" and the very high initial and upkeep cost of soaking pit furnaces.

Ingot washing is one of the greatest disad-' vantages of the conventional soaking pit and one which has never been satisfactorily overcome prior to my invention. It is due to the development in the heating chamber, of excessive temperatures-i. e., temperatures which are above the melting point of the scale formed on the ingots-resulting'in melting of the scale and consequent oxidizing of additional layers of the ingot, the ultimate result being substantial loss of tonnage. Moreover, the washed or melted scale runs downinto the furnace bottom where it seriously interferes with furnace operations and necessitates shutting down the furnace at intervals for cleaning and repair.

So far as I am aware the theory has heretofore been universally held among those skilled in the art of heating ingots in preparation for rolling that in order tosubject the ingots to a uniform penetrant heat it is necessary to burn the fuel in a combustion chamber separate from the heating chamber and conduct the more or less bumed gases into the heating chamber. The fact is, however, that this is exactly the wrong way of heating ingots for the purpose in question. It is difficult or impossible to avoid hot spotslocalized portions of the ingots which become overheated. It is dimcult to control the flame temperature and the temperature of the gases in the heating chamber. Apparently unburned particles of the fuel pass into the heating chamber where they ll invention will become apparent as the following 1 Claim. (Cl. 263-43) .are burned in intimate contact with the ingots under such conditions as to create undesirably high temperatures, resulting in washing of the in- I have discovered that, quite the opposite from heating ingots in conventional, soaking pits as has heretofore been considered necessary, the long existing problems can be solved and remarkably improved results obtained by heating the ingots by introducing unburned combustible material into the heating chamber wherein the ingots are disposed and burning the combustible material in said chamber in close proximity to the ingots. I preferably introduce unburned combustible material into the heating chamber through jets directed so as to deliver the'material alongside the ingots in said chamber and I provide for burning the thus introduced combustible material in the heatingchamber. Desirably the unburned combustible material is introduced in a plurality of streams directed so as to substantially uniformly distribute the combustible material about or among the ingots.

I flnd that the burning of the combustible material in the heating chamber in close proximity to the ingots results in avoiding the creation in the heating chamber of the high temperatures which cause ingot washing. While I do not limit myself to any theory of action, I believe that the reason for this is that the ingots absorb heat from. the flame before the flame can attain the undesirably high temperature which brings about washing. 1 I

By properly arranging the jets or burners I can produce in the heating chamber a much more uniform controlled heat than can be produced in a conventional soaking pit. The chemical composition of the gases and the flame temperature are thus maintained remarkably uniform with the result that the ingots are heated in a highly eflicient manner and at the same time more rapidly than is possible in a soaking pit.

I preferably introduce the fuel into the heating chamber through burners arranged in the furnace wall so that combustion of the fuel commences not earlier than approximatelyas the fuel enters the chamber. The fuel and air for supporting combustion may be mixed in the burnchamber and burned there.

. I 3 description of a present preferred embodiment thereof and a present preferred method of practicing the same proceeds.

In the accompanying drawings I have shown a present preferred embodiment of the invention and have illustrated a present preferred method of -.practicing the same, in which Figure 1 is a vertical longitudinal cross-- sectional view through an ingot heating furnace,

Figure 2 is a horizontal cross-sectional view through the furnace shown in'Figure '1,

opposed side walls 4 and opposed end walls 5.

The side and end walls form a substantially horizontally closed chamber for heating ingots disposed on the hearth 3. The furnace is closed by a cover 6.

The furnace shown differs from a conventional soaking pit in that there is no combustionchamber separate from the heating chamber and the furnace is not of the regenerative type. .The

fuel is introduced directly into the heating The products. of combustion pass out through an offtake I.

The burners are arranged in the side walls 4' as clearly shown in Figures 2 and 3. In the embodiment shown in the drawings each side wall has disposed alternately therealong series of three superposed burners 8 and single burners 8.

The burners 8 are directed straight inwardly of the wall. The burners 9 direct the fuel downwardly and inwardly. A burner 8 in one of the side walls 4 is opposite a burner 9 in the opposed side wall. n the other hand, it may be opposite a series of burners 8 in the opposed sidewall. The arrangement of all the burners is such that when fuel is admitted through them simulta neously and burned within the heating chamber a substantially uniform condition of temperature throughout the heating chamber is obtained.

Fuel is supplied to the burners in each side wall 4 through a pipe I 0 and air through a pipe ll. Branch pipes lead from the pipes III and 'II to the respective burners as clearlyshown in Figures 2, 3 and4.

Each of the burners is disposed and mounted within the wall 4 which carries it; The discharge end of each burner 8 is approximately at the inner surface of the wall, The burners '9 discharge the fuel downwardly into cavities 12' (Figure 3) in the walls, each such cavity having adownwardly and inwardly inclined bottom which directs the fuel toward the center of the furnace. In each burner 9 the fuel leaves the burner proper through a vertical duct l3 which discharges into the cavity l2 therebelow. There is provided an inspection and cleaning opening l4 closed by a sliding door l5.

I have not described the details of the furnace supporting structure, cover, I cover seal, cover operating means, etc,, because those details do not constitute the present invention. The furnace may take a variety of. forms so long as the fuel is introduced into and burned within, or largely within, the heating chamber.

conduit I6 which'is the subject of my copending 2,407,047. The cover is mounted on tracks I! and for present purposes may be considered as of conventional design.

Ingots are. as is customary in the art, charged into and discharged from the furnace by opening orrolling back the cover and introducing and withdrawing thev ingots by means of an overhead crane. They may. be arranged in any desired fashion on the hearth 8 within the heating chamber. The burners are so arranged that the ingots need not be disposed on the hearth in any particular pattern or relationship to one another. The streams of fuel issuing from the respective burners cooperate to produce a composite swirling flame in rather intimate contact withthe surfaces of the ingots and which results in uniform heating of the ingots throughout with little or no undesirable washing.

As indicated above, I have found that. the in- I 'troduction of the fuel directly into the heating chamber as described and the burning of it in intimate contactwiththe' ingots disposed in the heating chamber does not result ifi increased oxidation or washing; as might be supposed by those committed to the soaking pit theory, but on the' contrary results in decreased oxidation or washing. I believe this to be due, first, to the absorption of heat from the flame by the ingots themselves, as explained above, and, second, to the arrangement of the burners to create a uniform swirling flame about and among the ingots.

I can introduce fuel, and air virtually unmixed untilthey come together within the heating furnace and I find no excessive or harmful scale due to the action of the oxygen in the air on the ingots. On the contrary, a. relatively thin protective scale is formed which makes for high yield. It is desirable to have a substantial number of burners well distributed over the furnace walls so as to obtain a thorough intermixture of the gaseous streams issuin from the various burners. This largely eliminates individual streams impinging on localized portions of the ingots which might result in hot spots. In find that ingots can be'brought from a given initial tem- The cover 6 is sealed to the furnace by a water-cooled pipe or perature to a given final temperature in less time when heated by my process'and in my fur- I nace than has been possible previously in the use of soaking pits. This is true even without preheating the air used in my'furnace. With cold air I can obtain faster and better quality heating than can be obtained in a soaking pit with preheated air.

Another important advantage of my improved furnace, and which is incident to elimination of the combustion chamber or chambers heretofore considered necessary and always employed in soaking pits, is great simplification in furnace design resulting in a large saving in material and labor in construction and maintenance and in floor space. My furnace can be preconstructed and transported to the site of erection and placed on prepared foundations thus greatly reducing interruptions in mill operation due to installing the furnace. Of especial value in operation, construction and maintenance is the elimination of radial supportingbrick covers or thus eliminating dimculties incident to expanvariously embodied and practiced within the scope of the following claim.

I claim: In a soaking pit furnace for heating ferrous ingots, in combination, a rectangular heating 1 chamber having substantially vertical opposed walls, a plurality of burners positioned in a substantially regular pattern over a major portion of the surface of each of one pair of said opposed walls and adapted to constitute substantially the sole heating source for said furnace and to be in close proximity to said ingots, a majority of said burners on each of said pair of opposed walls being directed inwardly into said heating chamber in a direction normal to said apposed walls and adapted to project unburned combustible material about and among said ingots for combustion in said heating chamber, the remainder of said burners on each of said pair of opposed walls being directed downwardly and inwardly into said heating chamber in alternate relation to the burners in said majority of said burners, said burners on said pair'of opposed walls being arranged in successive spaced vertical planes substantially normal to said opposed walls, whereby ingots placed in said furnace in conventional manner are heated to uniform temperature in intimate contact with the flames from said combustion of said combustible material,

' CARL H. WEST.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Date copyright 1942, page 223, published by John Wiley 8: Sons, New York, N. Y.

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