US2603476A

US2603476A - Circular open hearth melting furnace

Info

Publication number: US2603476A
Application number: US116340A
Authority: US
Inventors: Howard C Whiston
Original assignee: Individual
Current assignee: Individual
Priority date: 1949-09-17
Filing date: 1949-09-17
Publication date: 1952-07-15
Anticipated expiration: 1969-07-15

Description

July 1s, 1952 Filed Sept. 1'7, 1949 H. C. WHISTON CIRCULAR OPEN HEARTH MELTING FURNACE 5 Sheets-Sheet 1 INVENTOR.

HOWARD C. WHISTON.

BY M, Mae/M ATTDRNE YS.

July 15, 1952 H. c. wHlsToN 2,603,476

CIRCULAR OPEN HEARTH MEL-'FING FURNACE Filed Sept. 17, 1949 3 Sheets-Sheet 2 JNVENTOR. HOWARD C.WH|STON.

ATTORNEYS.

July 15, 1952 H. c. wHlsToN 2,603,476

` CIRCULAR OPEN HEARTH MELTING FURNACE Filed Sept. 17, 1949 5 Sheets-Sheet 5 INVENTOR. A -HowARo c. wHlsToN.

ATTORNEYS.

d ll Miel Patented July 15, 1952 Howard C. Whiston, Clairton, Pa."

Application This invention relates, `as indicated, to an openhearth furnace, andrv more particularly,- to an open-hearth `furnace 'of circular shape having parts which provide -improvements from the standpoint of charging, production, and construction.

In conventional practice, open-hearthfurnaces are commonly elongated rectangular structures having end wallsqand side Walls supported by buckstays bound together by stays and tie rods.

-The Aopen-hearth :bath is--of rectangular shape positioned centrally 'ofi the furnace which is provided withreduced throats 'at its open ends providing .gas portsconnecting the furnace with a complicated brick` Achecker-Work arrangement or regeneratoi' whichrecovers heat from the exhaust gases. Slag'pockets .are formed at the base of the regenerator structure in the ends of the furnace. Cold air and gas is admitted at one end of the furnace, burned in the furnace, and the products of combustion are exhausted at the other end." The gasgproducts of combustion being exhaustedlfrom the r'other end of the furnace by reason ofthe necessity of reversing the flow of lthe products of .combustion through the furnace. Another ,clisadvantageof such furnaces is the fact that the slag Ytends to build up on the surface of the metal .bath adjacent the end of the furnace .from whichv the products of combustion are being exhausted, this surface slag operating as an insulating blanket interfering with the refining of the metal in the bath. Moreover, upon reversal of the .flow of products of combustion through the furnace, the slag contained in the pocket at theend of the furnace through which the gases vwere being exhausted is chilled and solidified by the relatively cold air contacting therewith. f

One of the principalobjects of this invention is to provide an improvedform of open-hearth .furnace which will reduce the rvarea required for a'furnace of a given refining/capacity, which will september 17, 1949, serialNo. 116,340 1o Cnims. (ci. ,zeep- 34) 2l Y eliminate the necessity of reversing the flow of products of combustion through the furnace, which will eliminate the formation of an insulating blanket `of vslag on the Ysurface of the bath within thefurnace, which will eliminate the chilling of slag in a pocket at the base of the chamber through ywhich the exhaust gases are vconducted, and Vwhich will simplify and reduce the cost of construction of the furnace. 'Iothese 'and related ends, the open-hearth fur'nacebf this in" vention is circular-in shape and provides an annular or ring-shaped'trough for 'containing'the bath of metal to be refined. The products of combustion are fed to the furnace 'inla direction generally tangenti'ally.` of the containerV or trough holding the metal to berened and arel exhausted downwardly througha flue opening positioned centrally of the .trough..The combi-nedl action of the burners in'feed'in'g .the 'gasestangentially to the furnace and of the central exhaust flue is effective to move the products of lcombustion aroundV the furnace in a circulanhelical or toroidal pathin a manner to be described. The movement `of the gas in'this .manner causes them to scrub the surfacev of the metal being refined to thereby prevent an accumulation .of slag on the surface of the metal which would .be eective to interfere with the refining of -`the metal in the bath;V In addition, a heat4 transfer device is located in thefexhaust passage or flueforithe furnace and is `operativetogcontinuouslytransfer heat to air being :fed to the furnace and the necessity of reversing the fiow'of gas through .the furnace 'is eliminated. -The top ofV theV furnace is Vremovable so that the'fur-nace may be chargedl with material fromabovelrather than through openings in the side aswheretofore vnecessary in conventional open-hearthfurnaces.

Other objects and advantages ofthe invention will become apparentfromfthe following description. A y n In the drawings there is shown a-preferred ernbodimentofA the invention. In this showing:

Fig. 1 isl a vertical sectional View of an openhearth furnace constructed in raccordance with i the principlesof this invention; l

Fig. 2 is a fragmentary sectional view of apart of the structure shown-in .I ig.,v 1 illustrating in section a stopper VVstructure; for closing r.the exhaust flue opening when the furnace is being charged;r A 4 y Fig. 3 Ais a sectional view `taxen substantially along the lines AIII-III of Fig. 1; and.

Fig. 4 is a'topplan view. Y

Inthe drawings, the --numeral'l designates'an `transversely extending tie rods and channels.

an annular trough or chamber 8 for holding a bath of metal 9 to be refined. The walls 3 and 4 and the base 2 are so formed that the bottom portion of the trough 8 has an approximately semi-circular surface in any vertical diametrical plane of the furnace. By giving the base of the trough 8 this shape, the maximum pressure of the metal in the bath against the walls 3 and 4 is maintainedV at a minimum. It is thus possible to reinforce the side walls 3 with circular straps I thereby eliminating the stays and tie rods. or channels heretofore required for supporting buckstays in position on conventional furnace structures. The inside of the walls 3 and 4 adjacent to the bath, 9 may also be sloped or have any desired contour. vThe structure thus far described will be found to lessen the cost of construction of an open-hearth furnace as compared to conventional rectangular furnaces having end and side. buckstays supported Vin position by In addition, the circular shape of the trough 8 provides 'a surface on the molten bath which is relatively long for a given furnace area. The cost of constructing the furnace is thereby materially reduced. VThe furnace parts 2 through 9 are fabricatedv from refractory material and cooling pipes (not shown) may be provided therein where necessary.

The furnace is provided with a removable roof Y, II of circular shape comprising a circular Ydisk of refractory material I2 supported from roof members (not shown) extending transversely of reinforcing rings I3. fiat supported typeas shown or. may be of selfsupporting archeddome construction. This roof may be quickly removed and replaced when necessary thus savingvaluable refining time in a mannernot possibleV with present conventional furnaces.

The reinforcing Arings I3 are supported on bracket members I4 mounted at spaced points around the edge of the furnace. Jack screws I5 are provided for initially jackingV the cover II upwardly with respect to the furnace I. The roof II may then be removed from the furnace by a crane lto` render its interior accessible for placingV therein a charge to be refined. When the roof I I is removed from the furnace for charging, a stopper member I6 is lowered into position the brackets I4 and is providedwith a plurality of downwardly extending air supply conduitsv I8 connected at their lower ends with burner nozzles I9 extending through the side wallsY 3 and terminating at positions adjacent the inner surface of the side wall 3. As best shown in Fig. 3, the nozzles I 9 project angularly into the furnace for The roof II may be either a delivering products of combustion into the furnace in a direction which may be described as being generally tangentialof Vthe trough 8. More specifically, each of the nozzles I9 project in a direction which is tangential to a circle lying between the walls 3 and 4 but closer to the wall 4 than to the wall 3 as shown in Fig. 3. Fuel, solid, liquid, or gas, is supplied to the burner nozzles I9 throughout conduits 20 connected with a circular fuel supply'bustle 2| mounted on the supports I4. Valves 22 are provided for adjusting the fuel flow feed to the burner nozzles I9 through the conduits 20. A damper 23 is provided in each of the air supply conduits I8 for adjusting the quantity of air fed therethrough. The burners may be operated with or without additional oxygen or compressed air together with any standard type of fuel-air ratio control to obtain the proper refining flame.

By reason of the tangential direction in which the angularly positioned nozzles I9 feed a combustible mixture of gases to the furnace 8,'itwil1 be seen that the burning products of combustion will be moved about the surface of .thev trough 8 in a generally circular'path. That is, Vthe burning products of combustion will move toward the inner surface of the outer side wall 3 and will be deflected by and moved around the furnace in a circular path about such inner surface. Referring to Fig. 3, it will be noted that the extended axis of each of the burner nozzles I9 intersects withthe outer side wall adjacent the next succeeding burner nozzle. By locating the nozzles in this manner, gas forced out of one of the burner nozzles will pick up and impel burning gases from the previous burner nozzle around the furnace. That is, the action of each of the nozzles I9 tends to keep the burning products of combustion already in the furnace moving in a circular path. f

As explained above, Vthe products of combustion are exhausted from the furnace downwardly through the circular flue opening 1. By exhausting the products (3f-combustion in this manner, thegases tendlto rotatein a circular path ina clockwise direction as indicated by the arrows in Fig. 1 as theymove in a circular path in a clockwise direction as .indicated bythe arrows'in Fig. 3. If desired, the-gases vmay also be directed in a counterclockwise path andthe burner nozzles I9 may be set at any angle desired by the furnace operator. The products of combustion thus tend to move in each of two different circular'paths, and thus will move in a circular helical or toroidal path around ther trough 8. The burning products of combustion will thus scrub all points on the surface of the bath 9 in the trough 8, and slag will be prevented from building up on any given area of the surface of the metal in the bath 9. Accordingly, it will be apparent .that this action will be effective to'prevent the formationl of an insulating blanket of slag onthe surface of the metal bath which would otherwise be effective to interfere with therefining of the metal in the bath.

In order to'accelerate the renement of the metal in the bath 9, a4 plurality of air nozzles or tuyres 25 are provided for blowing compressed air into the bath. The tuyres 25, in accordance with conventional practice, may be provided ,with water cooling pipes. As illustrated, the nozzles 25 project angularly downwardly and are connected with conduits 26 which supply air to the nozzles 25 from a circular bustle 21 mounted on supporting members 28 positioned about the periphery of the furnace. The provision of the metal from the furnace.

la Bessemer effect, and will cooperate with the action of the nozzles v[fito accelerate the refining of the metal `in the bath. A mixture of compressed air V and 'oxygenjor any other desirable gases, liquids,l orfso li ds;, with or without air may be blown in through the nozzles or tuyres 25.Y i y The furnace .is provided with one or more ports or openings 30 communicating :with the` `lowermost portion of the trough 8 for tapping 'refined One or more openings 3|l are provided at an upper vlevel for the surface of the metal nozzles V2? gives or ports tapping off 'slagv from in the furnace.

Although the furnace 'is charged from the top after removal of the cover Il asiexplained above, openings 32 are formed in the side walls 3 through which molten metal or .other materials may .be charged into the furnacev Vas required without removal of thefto'p Il or requiring stoppage of the refining operation ofthemetal in the bath. v l

As best shown in Fig. l, the'vertically d0wnwardly extending flue 1 connects at its base with a cross passage 34 which isconnectedwith an exhaust stack 35 having a damper 3S therein for controlling `the draft on the furnace.' The transverse passage 311i is provided with ,a depressed portion 37 providing a pocket at the base of the flue 1 in 4which molten slag maycollect. "l'rhe I molten slag may be tapped off from the depressed portion or pocket 31 as required throughV any suitable opening (not shown).

As shown in Figs. 3 and 4.the lbustle Il .is

provided with a downwardlyextending connection 39 to an air supply conduit 4S, having a conu nection with a heat transfer unit or recuperator indicated as a whole` and diagrammatically by the numeral 4i. The .recuperator llll may be any suitable heat transfer structure adapted to absorb heat from the products of combusti-on passing through the passage 34 and Vfortransferring such heat to air being delivered to the conduit 40. Since this invention is not concerned per se with the structure of the recuperator 4| `and any suitable heat transfer device may be employed for its purpose, the structure of the recuperator il has been illustrated diagrammatically only. An opening 38 is provided in the transverse passage 34 for the reception Iof the heat transfer. unit lli. The ,numerals i2 and 43 respectively indicate diagrammatically a fan `and operating lmotor therefore for forcing airto be heated through the recuperator 4|. The recuperator di delivers heated air to the conduit 40 which delivers the heated air through the connection 39 to. the bustle I1. From the bustle I1,.the heated air is fed to the nozzles, I9 as explained above...A In this arrangement, it will 4hefnoted that heated air is fed continuously to the bustle il without any complicated reversing process as required in conventional open-hearth furnaces. In this manner,

.the products of combustion flow. continuously through the exhaust flue 'Land slag collecting in the pocket 31 is never chilled by being subjected to ablast of relatively cold vair passing over the surface thereof. The slag in the pocket 31 is thus maintained in a molten condition and may be 'tapped off at any timev during the operation of the furnace. The furnace may also beY constructed Vand operated if vdesired without the use of-the recuperator 4l and the fan '42.' The burner nozzles i9 may also be any type of fuel burners now used in every-day practice.

From the foregoing, it Will be apparent that 6 this invention provides a novel form vof circular open-hearth furnace having therein an annular trough for containing the metal bath to be refined. Attention is particularly directed to the fact that the novel cooperationt of the burners in feeding a mixture of combustible 'gas in adirection tangentially of the trough @with the centrally located flue 'lis effective to' move the products of combustion over the surfaceof the metal bath in a toroidal path. Theentire surface of the metal bath is thus subjected to a scrubbing action by the products of combustion to facilitate andexpedite the refining 'of the metal in the bath. Attention is also particularly directed to the fact that the provision of an annular trough 8 provides a trough of considerable length within a comparatively small area'as compared to the area required for open-hearth furnaces of conventional construction, and the cost of constructing a furnace having a givenv capacity is reduced in comparison to conventional open-hearth furnaces. Attention is further directed to the factl tration, and that various'changes'and modificaf tions may be made therein Withinthe ccnte1n plation of my invention and vunder-the scope of the following claims. l u" Y* y I claim: 1 v i. In an open-hearthfurnace, the combination comprising a circular trough 'for' containing a l bath of metal to be refined, a 'fuel-burner' for lintroducing burning gases "into Vthe furnace in a direction generally tangential to a circle lying between the edges of the trough, and an exhaust fiue positioned centralfly'of said 'troughfor exhausting the gases from the furnace in a vertical- 1y ydownward direction, the motion imparted to the gases by said burner and said flue being effective to swirl the gases aroundthe trough in a toroidal path to thereby subject the surface of the metal bath in thev trough to a scrubbing actionby said gases.

2. En ran open-hearth furnace, the combination comprising acircular furnace base having a circular side wall about 'its periphery and a circular elevated projection at its center but of 'less .height than the wall and an opening centrally'of said projection, said side wall and projection cooperating to define a circular trough for containing a bath of metal to be refined a plurality of burners atspaced intervals about the furnace for introducing burning gases in a 'direction generally tangentialto a circle lying between the edges of the trough, and 'an exhaust Hue in cornl munication with saidl projection opening from the base of the furnacesaidburners and flue having a combinedaction eifectiveto -move the burn' irljsf gases in a toroidal path over'the Vsurface of vthe metal bath insaid trough fout of rthetrough by the scrubbing action ofthe products oi' `combustion on the 14 surface of the metalbatnV f 4. In :an open-hearth furnace, -thecombination comprising a circular .furnace base lhaving' a circular side Wall about its periphery and a circular elevated projection at its center -but of less height than the wall and an opening centrally of said projection, said side Wall-and projection cooperatingvtoedefine an approximately circular trough for containing abath of metal to be refined, an exhaust flue in communication with and extendingin a downward direction from said projectionV opening, a roof mounted for removal from the furnace to render said trough accessible from above for quickly charging the furnace with metal to be refined, and a stopper for mounting temporarily on said projection to cover said opening and prevent metal being charged into said trough from` entering said fiue.

5. In an open-hearth furnace, the combination comprisingra circular furnace base having a circular side wall about its periphery and a circular elevated projection at its center and an opening centrally of said projection, said side wall and projection cooperating to define a circular trough for containing a bath of metal to be refined, the portion of said base defining the bottom of said trough having a surface with a semi-circular shape in any plane extending transversely of said projection and side walls, an exhaust fiue in communication with and extending in a downward direction from said projection opening, burner means for subjecting the surface of the bath to the action of burning products of combustion to thereby provide an open-hearth refining action, and a plurality of tuyres respectively projecting at a radial and downward angle with respect to said trough for introducing air, gases, or any fluid or solid into the bath to provide an additional refining action of the Bessemer type.

6. In an open-hearth furnace, the combination comprising a circular furnace base having a circular side wall about its periphery and a circular elevated projection at its center but of less height than the wall and an opening centrally of said projection, said side wall and projection cooperating to define a circular trough for containing a bath 'of metal to be refined, a plurality of burners at spaced intervals about the furnace for introducing burning gases in a Vdirection generally tangential to a circle lying between the edges of the trough, an exhaust fiue in communication with and extending in a downward direction from said projection opening, said burners and flue having a combined action effective to move f the burning gases in a toroidal path over the surface of the metal bath in said trough, a roof mounted for removal from the furnace to render said trough accessible from above for charging the furnace with metal -to be refined, and a stopper for mounting temporarily on said projection to cover said opening and prevent metal being charged into said trough from'entering said fiue.

7. In an open-hearth furnace, the combination comprising a circular furnace base having a circular side wall about its periphery and a circular trough within said sidewall for containing f a bath of metal to be refined, a fuel burner for introducing burning gases into the furnace in a direction generally tangential to a circle lying between the edges of the trough, and an exhaust Vfiue positioned centrally of said trough for exhausting the lgases from the furnace in a vertically downward direction, the motion .imparted to the gases by said burner and said flue being effective to swirl the gases around thetrough in a toroidal path to thereby subject the surface of `tliemetal bath in the trough to a scrubbing 8. `In an open-hearth furnace, the combination comprising a circular furnace base having a circular side wall about its periphery and a circular trough within said side wall for containing a bath of metal to be refined, a fuel burner for introducing burning gases into the furnace in a direction generally tangential to a circle lying between the edges of the trough, and an exhaust flue positioned centrally of said trough for exhausting the gases from the furnace in a vertically downward direction, the motion imparted to the gases by said burner and said fiue being effective to swirl the gases around the trough in a toroidal path to thereby subject the surface of the Vmetal bath in the trough to a scrubbing action by said gases, a roof mounted on said side wall for removal from the furnace to render said trough accessible from above for quickly charging the furnace with metal to be refined, and a stopper for temporarily covering said exhaust ue to prevent metal being charged into the trough from entering the fiue.

9. In an open-hearth furnace, the combination comprising a circular furnace base having a oircular side wall about its periphery and a circular trough within said side wall for containing a bath of metal to be refined, a fuel Iburner for introducing burning gases into the furnace in a direction generally tangential to a circle lying between the edges of the trough, and an exhaust flue positioned centrallyv of said trough for exhausting the gases from the furnace in a vertically downward direction, the motion imparted to the gases by said burner and said flue being effective to swirl the gases around the trough in a toroidal path to thereby subject the surface of the metal bath in the trough to a scrubbing action by said gases, and a stopper for mounting temporarily on said exhaust flue to prevent metal being charged into the trough from entering the flue.

10. In an open-hearth furnace, the combination comprising a circular furnace base having a circular side wall about its periphery and a circular elevated projection at itsv center but of less height than the wall and an opening centrally of said projection, said side wall and projection cooperating to define a circular trough for containing a bath of metal to be refined, a plurality of burners atspaced intervals about the furnace for introducing burning gases in a direction such that said gases move in a generallyhorizontal annular path above said trough, and an exhaust flue in communication with said projection opening for exhausting thel gases from the furnace in a vertically downward direction.

HOWARD Ci. WHISTON.

REFERENCES CITE The following references areof record in the file of this patent:

Y UNITED STTES PA'IENTS Number Nissim Oct. 9, 1945