US1963846A - Furnace - Google Patents

Description

June 19, 1934. c. L. IPSEN ET AL FURNACE Filed Feb. 26. 1932 I (I i i/1111111111 Invenimrs;

L sens Ralph Ej cox,

Their Atto-r'neg.

Patented June 19, 1934 UNITED STATES PATENT OFFICE FURNACE Carl L. Ipsen and Ralph E. Schenectady, N. Y., assignors to General Electric Company, a corporation of New York I Application February 26, 1932, Serial No. 595,310 1': Claims. (Cl. 263-28) Our invention relates to furnaces and has for interposed between the hearth and the frameits object the provision of improved means for work is a quantity of comparatively light thermal conveying a charge or load into the furnace and insulating material, such as powdered diatomafor supporting the charge within the furnace ceous earth. The columns will be sufllciently 5 while it is operating. long to support the hearth plate in proper posi- 00 Our invention has particular application to tion within the heating-chamber when the car electric furnaces of the larger types designed for has been moved to insert the charge, and to perheating relatively large quantities of material mit the insertion of an ample amount of the inat one time. It is usual to provide furnaces of sulating material beneath the hearth.

this type with a hearth or floor mounted upon For a more complete understanding of our in- 65 a car or other supporting device which is arvention, reference should be had to the accomranged to be moved through an opening provided panying drawing in which Fig. 1 is an elevation for it in the furnace for the purpose of chargin section of an elevator type electric furnace 118 t furnace n Subsequently Withdr wing provided with a furnace or charging car embodythe treated charge. While the furnace is in oping our invention; Fig. 2 is a plan view of the 70 eration, the hearth or floor serves both to supcar shown in Fig. 1, portions being broken away port he c ar e and to close and thermally seal so as to illustrate certain structural details; and e furnace t0 Prevent the e ape of heat thr u h Fig. 3 is a vertical longitudinal sectional view of or by the hearth plate. a portion of the car shown in Fig. 2.

T e upp rt ca etof re e erally u ed Referring to the drawing, we have shown our is comprised a metallic frame supporting a lay r invention as applied to an electrically heated eleof th rm lly insulating brick-Work and n this vator type furnace intended to be used for anlay r e e t p te o fl tse wa urnorthealing sheet steel, malleable iron and the like. ed. Because the carisutilized to close and ther- It is t b underst od, ho ever, that we have S the furnace t -W ay 18 shown a car used in connection with a furnace so made of relatively thick and massive proportions. of t t merely for t purpose of m oftentimes this layer was made as thick or even t and t t t may he d in nn t o thicker than the walls deflninl he h in with a tunnel and similar type of furnace wherechamber. in charging cars are used as well as with the ele- Cars of this type H several objectionable to;- type furnace h n in the drawing. characteristics. In loading the car with the As hown, the elevator furnace comprises a char e. it is nerally n e sary to work w t pair of spaced side walls 10 and a top wall 11 the car cold or a room p r ur when the, defining a heating chamber 12 provided with a comparatively cold carisinserted in the furbottom charging opening 12a. It will be under- 86 pace the massive brick-work lining absorbs a stood that these walls forming the heating cham- 90 considerable quantity of heat. This is obiecher will be heat insulated. Thus, the walls will tionable because it results bothin a waste of elecbe provided with inner linings 14 constructed or trical energy and of time: more electrical energy some suitable high refractory and mechanically is required because of heat absorption, and bestrong heat insulating material, such as clay me- 40 cause this absorption robs the heating chamber brick, and with an outer lining or layer 15 conof heat more time is required to heat the charge. structed of bricks formed from a suitable insulat- In addition, the lining because of its great ing material, such as diatomaceous earth. Prefweight requires rather powerful apparatus to erably, the walls will be provided with an outer move the car into and out of the furnace. metallic lining l6.

45 It is an important object of our invention to As shown in Fig. 1, these walls are supported provide a furnace car having a comparatively in an elevated position by means of suitable small heat storage capacity, but yet having good columns 17. 7 thermal insulating characteristics, and further, Heating units 20, preferably of the resistor one having afrelativelylight andgmechanically type, are suitably mounted upon the inner sur- 50 strong construction: f faces of the side walls 10 for heating the cham- 1 5 In accordance with our invention we support her 12. the hearth or door of the car by means of a plu- It is usual to provide elevators of this type rality of relatively small, but yet mechanically with a car or some similar means on which the strong pillars or columns, which in turn are supfurnace charge 21 is loaded. Usually the charge as ported upon a suitable uctu al framework. is loaded on the car at some convenient point in the work or furnace room, after which the car is run to a position vertically beneath the opening 12a. A suitable mechanism, such as an elevator, is provided to elevate the car with the loaded charge to the heating chamber.

As has been pointed out above, it is an important object of our invention to provide an improved car or conveying means for the furnace charge.

The car comprises a suitable base or structural foundation 22 carried upon wheels 23. As shown, the structural framework constituting the foundation 22 comprises two pairs of spaced longitudinally arranged girders 24 and 24a. Each pair of these girders 24, 24a are spaced apart a suflicient distance to receive a pair of the wheels 23 on one side of the car between them, as clearly shown in Fig. 2. It will be understood that suitable bearings (not shown) for receiving the journals of the wheels 23 will be provided in the longitudinal members 24, 24a. The two girders of each set are secured together along their bottom edges by means of transversely arranged straps 25 which will be welded or otherwise suitably secured to the girders. The upper edges of the girders of each pair and of both pairs are secured together by means of transversely arranged beams 26, which likewise will be welded or otherwise suitably secured to the girders. While the girders 24, 2411 are shown to be of channel.

cross-section and the beams 26 of I-section, it will be understood that girders and beams having any suitable sections may be used.

Resting upon the beams 26 is a suitable floor 27 which preferably will be formed of suitable steel plates welded or otherwise suitably secured to the beams.

This floor serves to support a suitable hearth plate or floor 30 in an elevated position by means of pillars or columns 31. These columns are secured to longitudinally arranged beams 32 which rest directly upon the floor 27 and are secured thereto in any suitable fashion as by means of welding. These. beams, as shown, are spaced at substantially uniform intervals crosswise of the floor.

The columns, as shown more clearly in Figs. 2 and 3, are provided at their lower ends with flanges 33 which are secured to the beams 32 by means of bolts 34. As shown, the beams 32 have an I-section, and the column flanges 33 are so arranged that the bolts 34 securing them may be passed through the flanges of the beams on opposite sides of the beam webs.

The hearth plate or floor 30 preferably will be formed of a plurality of rectangular sections. As shown more clearly in Fig. 2, each section is supported on a plurality of the columns 31. [n the particular embodiment illustrated each plate rests on six columns.

The columns 31 preferably will be formed of hollow sections, and each plate 30 will be provided with downwardly projecting protuberances or stud-like members 35 which are received in the hollow columns to prevent lateral displacement of the hearth.

Interposed between the hearth plate 30 and the structural foundation 22, that is, interposed between the hearth plate and the floor 27 is a suitable thermal insulating material 36 filling the spaces all around and about the columns 31. This insulating material will be formed of a relatively light substance having a relatively low heat capacity and a relatively low heat conductivity, such as powdered diatomaceous earth.

This material has a weight of approximtely 16-17 pounds per cubic foot, a specific heat of approximately .22 and a thermal conductivity of approximately .5-l.0. The thermal conductivity approaches the higher value as the furnace temperhearth plate, whereby when the space defined by.

the retaining wall has been filled with the powdered insulating material 36, the upper surface of this material will be brought to a plane slightly below the plate 30.

Preferably, and as shown, the hollow columns 31 also will be substantially filled with the diatomaceous earth 36.

For the purpose of directing the car to a posi tion vertically beneath the furnace opening 12a (shown in dotted lines in Fig. 1), we have provided suitable supporting guide rails 40, the wheels 23, as shown, being flanged to retain the car on the guide rails. It will be understood that any suitable means may be used to elevate the car from this dotted line position to its working position (shown in solid lines in Fig. 1) for this purpose, a suitable hydraulically operated elevator (not shown), provided with a plunger 41 for engaging and supporting the car, may be used.

The car is provided with a trough 42 surrounding the base portion of the wall 37 for receiving a quantity of sand 43 or some similar sealing medium. The furnace is provided with a depending flange 44 surrounding the opening 12a, this flange dipping into the sand 43 when the furnace car is raised to bring the charge 21 into the heating chamber. By reason of this arrangement, when the furnace car is moved into its elevated position, shown in Fig. 1, the space between the car and the walls defining the opening 120. will be sealed.

In the operation of the furnace, it will be understood that the charge 21 will be loaded on the car at some suitable place usually removed from the supporting columns 1'7 and then moved to a position vertically beneaththe furnace charging opening 12a, from which position it is elevated by the plunger 41 to carry the charge into the heating chamber. The car is supported in its elevated position until the charge has been satisfactorily treated whereupon the car is lowered to its rails 40 and run to a convenient position for unloading. While the car is in its elevated position, shown in Fig. 1, the insulation 36 and the sand seal 43, 44 prevent the escape of heat from the chamber 12 through the charging opening 12a.

It will be observed that the hearth plate 30 which serves to support the furnace charge 21 is supported from the structural steel foundation 22 by means of a plurality of pillars 31 which are relatively small in width as compared to their length, and which at the most contact with but a relatively small area of the under surface of the hearth plate. Consequently, there is little opportunity for escape of heat from the chamber 12 by way or the columns 31., In addition to this, the columns 31 preferably w ll be formed of hollow sections both because such sections give greater strength for a given cross sectional area, and for a. given strength requirement reduce the area of contact between the columns and the hearth plate to a minimum.

It is to be noted also that the insulating material 36 which fills the hollow columns 31 and the space around and about the columns, and which substantially fills the vertical space between the hearth plate and the fioor 27 completely thermally insulates the furnace car; when the furnace is operating to support the charge 21 in the heating chamber, the upper ends only of the columns 31 are exposed to the heat with the result that but a very small quantity of heat will be transmitted through the columns to the structural framework which supports them.

In addition to the fact that the columns are very small in cross sectional area and by reason of this will conduct very little heat through them, it will be observed that these members and their insulating medium 36 have a very small heat capacity and consequently will absorb but a small quantity of heat from the heating chamber when the furnace charge is inserted in the chamber. This is a very important feature of our invention because, as has been pointed out above, it is usually necessary that the car be loaded when the temperature of the car is either cold or at room temperature, and so, if the combined masses of the pillars and of the hearth plate 30 were considerable, a large amount of heat absorption would take place when the car'is inserted in the heating chamber. In our invention, there is practically no heat absorption because the relatively light powdered diatomaceous earth 36 constitutes the major portion of the bulk of the car.

The advantages of my arrangements are apparent; in view of the fact that there is practically no heat absorption by the car when the charge is inserted, the charge will be brought up to heat more quickly with the result that there is a saving both of electricity and of time.

In addition; it will be noted that our car is relatively light in weight as compared with the cars heretofore generally used wherein a very thicklayer of insulating brick is used to support the furnace charge, with the result that the elevating mechanism required to raise and lower our car need have but a fraction of the power required to elevate those heretofore used.

While we have shown a particular embodiment of our invention, it will be understood, of course, that we do not wish to be limited thereto since many modifications may be made, and we, therefore, contemplate by the appended claims to cover any such modifications as fall within the true spirit and scope of our invention.

What we claim as new and desire to secure b Letters Patent of the United States, is,-

1. A furnace comprising walls defining a heating chamber provided with a charging and discharging opening and means for conveying a charge into and from said chamber through said .opening comprising a fioor for receiving said charge, a base, pillars on said base supporting said floor in spaced relation with said base, and thermal insulating material having a thermal conductivity of approximately .5-1.0 and a specific heat of approximately .22 interposed between said base and said floor.

2. A furnace car comprising a foundation,

' means movably mounting said foundation, load supporting pillars mounted on said foundation, a charge receiving hearth supported on said pillars and thermal insulating material surrounding said pillars having a weight of approximately 16-17 pounds per cubic foot, a thermal conductivity of approximately 5-1.0 and a specific heat of approximately .22.

3. A car for conveying charges into and out of a furnace and the like compring a base, a charge supporting floor in spaced relation with said base, thermal insulating material having a thermal conductivity of approximately .5-l.0 and a specific heat of approximately .22 interposed between said base and said floor and means supporting said floor on said base independently of said insulating material.

4. In combination with a furnace, a car comprising a structural foundation, means movably mounting said foundation, a plurality of columns relatively narrow as compared with their height secured at their lower ends to said foundation, members constituting a hearth supported on said columns and thermal insulating material having a weight of approximately 16-17 pounds per cubic foot, a thermal conductivity of approximately .5-1.0 and aspecific heat of approximately .22 interposed between said hearth and said foundation and filling the spaces between said columns.

- 5. In an electric furnace, a car for conveying charges into and out of said furnace comprising a structural metallic body, supporting wheels secured to said body, metallic columns supported on and secured to said body, metallic plates resting on said columns anddefining a hearth and a layer of powdered insulating earth having a thermal conductivity of approximately .5-1.0 and a specific heat of approximately .22 filling the spaces between said columns.

6. An electric furnace comprising walls defining a heating chamber, a hearth in the bottom of said chamber, columns supporting said hearth, a car structure securing and supporting said columns, means thermally insulating said hearth from said car structure having a weight of approximately 16-17 pounds per cubic foot and having a thermal conductivity of approximately .22, and means for moving said car structure into and out of said heating chamber.

7. In an electric furnace of the elevator type comprising a. heating chamber provided with a bottom opening therein, a furnace car adapted to be elevated into and to be lowered from said bottom opening and to close said opening when said furnace is operating comprising a base provided with wheels constituting a carriage, a hearth, a plurality of columns mounted on said base and supporting said hearth in spaced relation with said base, said columns engaging but a relatively small portion of the area of said hearth and a layer of powdered thermal insulating material having a weight of approximately 16-17 pounds per cubic foot, a thermal conductivity of approximately .5-1.0 and a specific heat of approximately .22 interposed between said heart and said base.

8. In an electric furnace, a car for conveying charges into and out of said furnace comprising a structural framework, a floor supported by said framework, longitudinally arranged beams on said fioor', a plurality of columns supported by and secured to said beams, a hearth resting on and supported by said columns, powdered insulating material interposed between said floor and said hearth and filling the spaces around and about said columns and walls mounted on said structural framework retaining said insulating material.

9. A furnace car comprising a structural base, wheels mounting said base, a hearth floor, cola I) u turms secured to said base and. arranged to support said hearth floor in spac elation with said base, said columns being v narrow as compared with their height and lining outwardly at their upper ends but engaging but a corn' pairatively small area of said hearth and a layer of diatomaceous earth between said hearth and said base.

10. A furnace car comprising a metallic structural base, a metallic floor on said base, a plurality of tubular metallic colu on said base, a second metallic floor suppor on said columns, a wall on said base siu'roui g said columns, powdered diatomaceous ear 1 arranged around and about said columns supported by said first floor and retained by said wall and powdered diatomaceous earth substantially filling said tubular metallic columns.

ii. In combination with an electrical furnace provided with walls defining a heating chamber having a bottom opening therein through wl-ch charges are carried into and out of said heating chamber and means supporting said he chamber in an elevated position, a car for p-- orting the furnace charges comprising a structural base, a plurality of columns mounted on base, a hearth supported by said columns, powdered insulating material filling a t-ial portion of the space between said base and said hearth plate, said powdered insulating material having a thermal conductivity of approximately 5-1.0 and a specific heat of approx "lately .22, a wall on said base surrounding said columns for retaining said insulating material, and means providing a thermal seal between the pe- 1 portions of said base and the mouth of ding. it furnace car comprising a base, a pluof load supporting columns on said base i. o hearth floor supported on said columns consisting of a, plurality of separated metallic plates of relatively small area as compared with the total area of said floor and providing an unbroken loading area.

13. A furnace car comprising a base, a plurality of load supporting columns on said base, a plurality of separated metallic plates supported on said columns so as to establish an unbroken loading area, each plate having a relatively small area as compared with the total loading area, and locking means between said plates and said columns preventing lateral displacement of said plates.

said

14. A car for conveying a charge consisting of relatively large flat plate-like members into and out of a high temperature furnace comprising a base, a plurality of tubular load supporting columns on said base, a plurality of separated metallic plates supported on said columns so as to establish an unbroken loading area, each plate having a relatively small area as compared with the total loading area, and an insulating material havlng a relatively low heat conductivity and heat capacity interposed between said plates and said base and filling the spaces between said columns.

15. In an electric furnace, a car for conveying charges into and out of said furnace comprising a structural metallic base, a plurality of longitudinally arranged metallic beams spaced at intervals crosswise of said base, a plurality of columns supported on each of said beams spaced at intervals longitudinally thereof, metallic plates resting on said columns and constituting loading area, and insulating material filling the spaces between said columns.

16. A furnace car comprising a structural metallic base, a floor of said base, a plurality of longitudinally arranged metallic beams spaced at intervals crosswise of said floor, a plurality of columns supported on each of said longitudinally arranged beams spaced at intervals longitudinally thereof, a hearth floor resting on said columns, and insulating material filling the spaces between said longitudinally arranged beams and between said columns.

17. Afurnace car comprising longitudinally arranged girders, supporting wheels provided with bearings mounted in said girders, a plurality of metallic beams arranged crosswise of said girders and supported thereon spaced at intervals longitudinally thereof, a floor supported by said beams, a plurality of beams arranged longitudinally of said floor and spaced at intervals crosswise thereof, a plurality of columns resting on each of said last named beams spaced at intervals longitudinally thereof, means securing said columns to said last named beams, a plurality of separated metallic plates resting on said columns constituting a loading area and insulating material having a relatively low heat conductivity and a relatively small heat capacity filling the spaces between said last-named longitudinally arranged beams and said columns.

CARL L. IPSEN. RALPH E. COX.

Images