US2975734A - Furnace roof construction - Google Patents

Description

W- A. VOGT FURNACE ROOF CONSTRUCTION March 2l, 1961 Filed May 26, 1958 INVENTOR. l/V//l/'am A. l/og llll amount of plantoor space in'wh'ich .to function.

United StaleS Pfit 2,915,134 FURNACE Roon coisrsrnuc'rrols william A. Vogt, 71zQM0raganoad, Lafayette, Calif.

Filed May 2,6, 1958,1Ser. No. 737,787

z claims. arci.- iiowsia v; iA l This 'invention relates tolindustria'l furnaces, andk more particularly tofurnaces `of the yopen hearth type usedV 'in the refining of steel.

Since its inception, the-.openphearrth furnacefhas 'been chargedthrough spaced openings or doors in the front wall, this being necessary on account of the limitations imposed bythe compromise 'between maximum furnace capacity ,and theabsence of ilexibility `in presently utilized charging methods and equipment. 'This charging equipment comprises, heavy, cumbersome and relatively costly machines, which are .not only slow and time consuming in their operation, but require `an unduly large The machines are inherently limited in their capacity, due tortherestrictions imposed by the limited size of Vthe door openings and the relativelylsrnall .space `in which they .are required to operate. Due to .these limitations, the vnumber .of charging lboxes. which `must Ibe handled duringacharging Yoperation is such that a .great deal of time is consumed by A.the large number of .charging machine operational cyclesrequired. While the time `required to charge an open hearth furnace rvaries fromone plant to another, on account .of local facilities and `individual `furnace capacities, it is a matter of record that a modern .open hearth furnace, of approximately 225tons capacity, requires achargng time of from .twoptofour hours. 'A

VAIncidental .to .the fact that .the vcharging operation extends over a relatively long period of time, is the further fact that thecharging doors, 'in the front wall of the furnace, must .of Anecessity remain open to accommodate this operation. 'It is obvious that these openings located as ztheyare,below -thealevel of the underside-'of the furnace lroof, `.permit 4infiltration -of .cold air in such quantitles asto lower vconsiderably fthe thermal efficiency of the furnace. Also, the cooling effect of this air, irnpinging upon the furnace walls, is especially detrimental to the silica brick which forms part of the furnace lining, and definitely curtails the life of this refractory material. The use of the presently accepted furnace charging equipment has influenced furnace design, the trend being toward a construction which would contribute to more efficient charging operations. While this is unquestionably a desirable advance with regard to charging simplication, unfortunately these changes have an adverse elfect upon bath area, gas and air volume ratios, flame location, and, further, complicate furnace construction.

A closer approach to a more uniform placing or spreading of the charging material by presently accepted methods is not possible without unduly increasing the number of charging openings, in fact it has even been suggested that the entire side of the furnace should be removable. Of course, the tremendous heat loss involved, and the obvious structural problems which would be created by such a construction, render it entirely impractical..

While the foregoing disadvantages have long been apparent, up to the present time no'practical solution has been made available either to appreciably simplify the 2 charging operation, or shorten 'the time necessary for its performance. It has been recognized that a furnace which could be charged through the roof lwould not only render the use vof `expensive and :elaborate charging equipment entirely unnecessary, but would afford a substantial reduction in the furnace charging time. With the use of large capacity, bottom dumping buckets, charging scrap, which constitutes approximately sixty per cent of the. charge, und with these` buckets being handled by Va conventional overhead traveling crane, the chargv time could be reduced to a maximum of `approxiinately thirty minutes regardless of the furnace capacity,

and the space presently required by the. charging machines now in use could be utilized' to better` advantage.

.A further advantage whichwould accrue Afrom such an arrangement, lresides in the fact that the air infiltration which now takes place while the charging openings are uncovered, would be entirely eliminated in a roof charged furnace, as no circulation would take place through the top openings. v

A furnace-constructed with a plurality of longitudinally aligned openings in the roof would permit of a more uniform distribution of the charged material as each charge, being dropped vertically in a preselected and centrally disposed location, would spread out radially in all directions. This method -of charging would preclude any advantages that may have `existed in furnaces of asymmetrical .cross-sectional configuration, and the departure from Vstraight vertical walls with its attendant complicated ,construction would-no longer be necessary.

More `.or less radical and unrealistic approaches to the foregoing have been made 4in an vattempt Vto improve open hearth furnace operations. Suggestion has been made for providing -a roof which could be entirely removed' for charging purposes. A further suggestion covers the provision of a roof which being pivotally mounted along one edge'could be swung upwardly and outwardly, simulating the action of a hinged cover or lid of a box. Obviously, the .structural difiiculties and mechanical problems which would be encountered in an attempt to reduce these ideas to a practical basis can be considered as being unsurmountable. Also a means of controlling the enormous amount of heat which would be released by the removal of such roofconstruction would present a problem the solution to which would be virtually limpossible to attain.

It is the principal object ofthe present 'invention to provide a furnace .with a greatly reduced charging time as compared to present Yday standards.

A further object of the invention is the provision of a furnace having a relatively high thermal eliciency.

Another object of the invention is the provision of a furnace which can be charged without the use of special equipment, and which will result in a more economical utilization of plant lloor space.

Another object of the invention is the provision of a furnace which will permit of a more uniform distribution of charged material. I

A still further object of the invention is the provision of a furnace which will be relatively easy to maintain.

These and other objects will become apparent during the course of the following description and' appended claims,4 taken in connection with the accompanying drawing forming a part hereof.

On the drawing:

-Figure 1 is fragmentary plan View of a prefer-redembodiment of my invention showing a typical charging opening.

Figure 2 is a longitudinal vertical cross section taken on line 2--2 of Figure l showing the cover in place.

Figure 3 is a transverse vertical cross section taken on line 3 3 of Figure 1 showing the cover in place.

Referring to the drawings in detail:

The roof of an open hearth furnace is provided in spaced alignment, along a longitudinal median line, with -a plurality of -circular charging openings 11 communicating with the interior'of the furnace F. The number of openings provided will be governed by the furnace hearth proportions, the relationship between the length and the width being of especial significance. Generally speaking, the portion of the hearth bath served by each opening will be substantially square in area, relative to a horizontal plane.

It will be noted that the roof 10 is of a sectionalized design and is a combination of substantially identical type through the roof.

sprung arch and suspended-roof construction..- The-n'- dividual units 13 of the beam 12 are suspended in the conventional manner from a superstructure S as indicated by hanger rods 14.

The exterior sides 15 of the individual outer units 13 are formed in downwardly diverging relationship forming in effect, in longitudinal vertical section relative to the furnace proper, confronting faces of adjacent beams 12 which, acting as skewbacks, support the segments 16 of the polygonal structure 17 surrounding the opening 11. This method of construction will be clearly understood by reference to Figure 2. t

The polygonal structure 17, which in the preferred embodiment is illustrated as being octagonal in form, will follow the general contour of the roof 11. The individual refractory units forming the sides of the polygonalV Vstructure are all formed with downwardly converging faces 18, as illustrated in section on Figures 2 and 3, and as further indicated by broken lines on the plan view Figure 1.

Except for the fact that all the bricks in the roof 10 which are contiguous with faces 118 have their contacting surfaces complimentary thereto, the remainder of the roof 10 follows the conventional pattern for this type of structure, the main arch being supported by skewbacks 19 held in place and stayed in the usual manner.

The circular opening 11 centrally located in the polygonal structure 17 has sides 20 which converge downwardly and are adapted to receive an annular member 21 having a depending skirt 22. This skirt has a tapered form complementary to the sides of the opening 11, it will be apparent therefore, that when the depending skirt 22 of the annular member 21 is firmly set in place in the opening, the wedging action set up thereby, acting radially in all directions, will positively lock all of the units forming the individual panels of the roof 10, firmly lin place.

The annular member 21 fis provided with an upper outstanding ange 23 having a concentric groove in its top side whereby a sand seal can be formed for the reception of a cover 24 as indicated on Figure 2. The annular member 21 ispreferably cooled by means of circulated saturated steam, however, as this construction of cover, seal and cooling method follows conventional practice, it will notv be further described herein.

From the foregoingl it will be apparent that I have disclosed a novel method of roof construction which will make it possible to charge a furnace of the open hearth It will also be obvious that all the operations, ordinarily pertormed during the charging of the furnace, can be accomplished by standard overhead material handling equipment. closed a preferred embodiment of my invention, it will be understood that modifications maybe made within the spirit and scope of the appended claims.

I claim: p

1. A furnace roof construction comprising a plurality of suspended transverse beams, said beams being in spaced and parallel relationship, the confronting faces of adjacent beams being adapted to form opposing skewbacks, a panel of bricks interposed in the space between each pair of adjacent beams and being supported thereby, said panel being of arcuate form relative to its transverse vertical cross-section, substantially straight relative to its longitudinal vertical cross-section and having its transverse edges sloping inwardly and downwardly complementary to the confronting faces of said beams, an annular member set into said panel and being adapted to form a charg ing opening therein, a depending skirt extending from References Cited in the le of this patent UNITED STATES PATENTS 1,500,504 Lenk July s, 1924 2,159,844 Dean May 23, 1939 2,742,023 Reintjes Apr. 17, 1956 While I have dis-

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