US3559972A

US3559972A - Furnace apparatus

Info

Publication number: US3559972A
Application number: US778883*A
Authority: US
Inventors: Melvin J Greaves; Tage Werner
Original assignee: Arthur G McKee and Co
Current assignee: Arthur G McKee and Co
Priority date: 1966-01-17
Filing date: 1968-08-29
Publication date: 1971-02-02
Anticipated expiration: 1988-02-02

Abstract

Shaft furnace apparatus comprising an upstanding furnace shell, and a supporting structure comprising a frame surrounding and spaced from the shell including generally horizontally disposed frame members joined end to end and being of substantial depth and having sides facing the shell, spaced legs supporting the frame, and a plurality of connector means fixed to such sides of the frame members and to the shell to support the shell from the frame, and means connected to the members forming the frame to resist tilting of the frame members about generally horizontal axes during expansion of the shell on heating of the furnace. Preferably, at least 25 percent of the weight of the furnace above the bosh portion is at all times supported by the supporting structure. If desired, the hearth portion of the furnace may be suspended below the frame and be essentially unsupported from below.

Description

United States Patent 3,253,906 5/ 1966 Secord 266/25X 2,825,547 3/1958 Vaughan (220/15UX) 3,129,836 4/1964 Frevel 220/1 Primary Examiner-J. Spencer Overholser Assistant Examiner.l0hn E. Roethel Att0rneyBosworth, Sessions, Herrstrom and Cain ABSTRACT: Shaft furnace apparatus comprising an upstanding furnace shell, and a supporting structure comprising a frame surrounding and spaced from the shell including generally horizontally disposed frame members joined end to end and being of substantial depth and having sides facing the shell, spaced legs supporting the frame, and a plurality of connector means fixed to such sides of the frame members and to the shell to support the shell from the frame, and means connected to the members forming the frame to resist tilting of the frame members about generally horizontal axes during expansion of the shell on heating of the furnace. Preferably, at least 25 percent of the weight of the furnace above the bosh portion is at all times supported by the supporting structure. If desired, the hearth portion of the furnace may be suspended below the frame and be essentially unsupported from below.

PATENTEU FEB 2:971

SHEET 3 OF 6 l N V L N T0 R S PATENI EU FEB 2191:

sum s or 6 Hmmkcm ATI'OP/l/EYJ FURNACE APPARATUS (ROSS REFERENCE. TO RELATED APPLICATION This application is a division of applicants copending appli cation Scr No, 520.945, filed .Ian. 17. Who Pat. No 3.43 l ,fill

This invention relates to blast furnace structures and more particularly to improved means for supporting blast furnaces.

In the United States, blast furnace structures heretofore conventionally used generally have included a massive foundation set into the earth; the lower portion of the furnace including the hearth and bosh has been supported by this foundation. lhe upper portion of the furnace, including the shaft and furnace top including the bells, distributor and upper portions of the downcomer, has been supported by a mantle that, in turn, has been supported on the foundation by numerous columns surrounding the lower portion of the furnace in close proximity to each other and to the lower portion of the furnace.

Such furnace structures have certain advantages in that the upper part of the furnace including the shaft and top supported by the mantle have been free to expand thermally as a unit on heating of the furnace. The downcomer attached to the furnace top also becomes heated during operation of the furnace, so it also expands and contracts with the portion of the furnace above the mantle, thus minimizing difficulties that might otherwise arise from thermal expansion.

However, in such furnace structures there have been substantial difficulties arising from the differences in the thermal expansions of the supporting columns and the lower portion of the furnace below the mantle. The mantle-supporting columns themselves are not subjected to sufficient heat to cause them to expand appreciably, but the lower portion of the furnace is subjected to high temperature heat; therefore, the lower portion of the furnace tends to expand substantially on heating of the furnace until it bears substantially all of the weight of the furnace above the mantle and the apparatus supported by such portion of the furnace. On cooling, the lower portion of the furnace contracts and the entire load again is transferred to the columns. It, therefore, has necessarily been the practice to make the columns strong enough to support the upper portion of the furnace and apparatus supported thereby, and also to make the lower portion of the furnace strong enough to support the upper furnace portion and such apparatus; this has involved substantial added costs. Furthermore, the lining of the furnace in the vicinity of the mantle has been susceptible to excessive deterioration because of localized expansion and contraction arising from transfer of the load from the columns to the lower portion of the furnace and vice versa. The expansion joint often provided at this location to minimize this problem, itself has been a source of trouble.

In conventional European blast furnace structures, the lower portion of the furnace including the hearth and bosh, and the upper portion of the furnace including the shaft but not the furnace top, are supported from a massive foundation set into the earth. The furnace top, including the loading equipment and downcomers, is supported from this foundation by long posts or columns. This design tends to overcome the above described disadvantage of American-type structures, but introduces new problems. The bosh jacket is a structural element that supports the shaft of the furnace; consequently, a hot spot in the bosh can impair the support for the shaft; furthermore, the necessity for maintaining the bosh jacket as a structural supporting member increases the difficulties of relining the bosh. This design also makes it difficult to maintain a satisfactory tight joint between the furnace top and the portion of the furnace below the top, since the portion of the furnace below the top tends to expand on heating whereas the columns supporting the top do not expand appreciably if at all; this problem is accentuated when high top pressures are used according to modern practice. Other problems arise because the downcomer, supported from the columns, expands clue to heat while the columns themselves LII do not expand, and because a portion of the charge-distributing apparatus is usually supported by the furnace top and moves as the furnace expands, and a portion is supported from the posts and does not move from thermal expansion, so jamming of distributor parts or gas leakage at the distributor may occur.

In conventional American furnace structures. as well as in most European structures. the columns or posts that support the upper portions of the furnaces are so closely spaced in relation to the lower portions of the furnaces, as well as to each other, that they impair access to the lower portions of the furnaces for operations such as tapping, closing the tap holes and removing slag or spilled metal; they particularly impair access to these portions of the furnaces by automatic machinery for performing these functions. Moreover, since the legs are closely disposed relatively to the furnace, they can be damaged by molten metal in the event of breakouts. Furthermore, in both American and European furnace structure, it is very difficult, time-consuming and expensive to line the furnace, particularly the bosh and lower inwall portions which most frequently require lining, primarily because of the difficulties of access to the furnace caused by the closely spaced columns and by the constructions of the bosh and hearth portions which must act as supports for the upper furnace portions.

It is an object of the present invention to overcome as many of these problems and disadvantages as are desired. Another object is the provision of a blast furnace structure in which the portion of the furnace above the bosh, including the top, may be largely, or if desired entirely, supported by legs or columns at all times during heating and cooling of the furnace. This minimizes or eliminates disadvantages of American-type furnace structures such as those arising out of transfer of the support of the portion of the furnace above the mantle from the supporting columns to the lower portion of the furnace and vice versa; and also eliminates the disadvantages of Europeantype furnace structures such as those arising from the necessity to maintain the bosh jacket as a support for the shaft, from the difficulty of sealing the independently supported furnace top to the shaft. and from expansion of the downcomers and distributor parts relative to the nonexpanding supporting posts supporting the furnace top,

A further object is the provision of a blast furnace structure in which the portions of the furnace above the mantle location, as well as the furnace top if desired, are supported by widely spaced legs that permit greatly increased access to the furnace for operations and use of automated equipment and repair or replacement of lining, and that reduce possibilities of damage to the legs in the event of breakouts of molten metal. Another object is the provision of a furnace structure of the above type in which the hearth is suspended from the furnace shell and not supported from below, so that the entire furnace is supported at all times from legs and both the upper portion and the lower portion of the furnace can freely thermally ex pand and contract.

These and other objects of the invention will be apparent from the following description of several embodiments of the invention in connection with the accompanying drawings in which:

FIG. I is a perspective of a blast furnace structure embodying the invention and having a suspended hearth portion, parts not pertinent to the disclosure being omitted for clearness;

FIG. 2 is a vertical cross section, along line 2-2 of FIG. 1, parts being omitted for clearness;

FIG. 3 is a section along line 3-3 of FIG. 2 showing in plan the main supporting frame and lower centering means for the furnace, the scale being larger than in FIGS. 1 and 2; 1

FIG. 4 is an enlarged detail along line 4-4 of FIG. 1 showing one of the means connecting the surrounding frame of the supporting structure to the furnace shell;

FIG. 6 is a somewhat diagrammatic side elevation of the supporting structure. illustrating prestressing and preforming of the supporting structure before the load is applied.

Fl(i 7 is a vertical section to an enlarged scale of one of the supports for the legs.

HO. 8 is a section along line 8-8 of HG. 7.

FIG 9 is a detail of another embodiment of the invention in which the hearth is supported from the bottom but in which the remainder of the furnace structure is essentially the same as in FIGS 1-8. parts being omitted for clcarness'.

FIG. 10 is an enlarged detail. corresponding generally to H6. 4 in the location from which the section is taken. showing alternative means for connecting the surrounding frame to the furnace of HO. 9 and alternative cooling means; and

HG. H is an enlarged detail. also corresponding generally to FIG. 4 in the location of the section. of another embodi ment showing another means for connecting the furnace to a surrounding supporting frame.

ln the furnace structure of FIGS. 1 to 8. inclusive. the furnace l is supported entirely free of the ground by supporting structure 2. The furnace 1 comprises shaft 3. bosh 4 and hearth portion 5. all enclosed in a continuous steel shell 6 free of sharp bends below its connection to supporting structure 2 to provide adequate strength for the suspended portion of the furnace. shell 6 comprises shaft shell portion 7. bosh jacket 8 and hearth jacket 9. The furnace top is generally indicated as 10.

The supporting structure 2 comprises a frame 12. surrounding and spaced from the furnace l in the vicinity of the ring 13. which is preferably located in essentially the same vertical relationship to furnace shaft 3 as a mantle in a conventional furnace, Frame 12 is supported by four legs 14 from foundation members l set into the earth.

The furnace top of the illustrated structure is conventional and includes a large bell hopper 16 containing a large hell (not shown). a superposed rotatable distributor 17, the lower end of which is closed by a small hell (not shown). and a receiving hopper 18 above the distributor into which burden or charge material is charged. All of these parts are supported by the furnace from the top of the furnace shaft. Burden material may be conventionally charged into the receiving hopper by belts or skip cars traveling on a bridge (not shown).

Uptakes 21 are connected in conventional manner to the interior of the top portion of the furnace, and discharge into a downcomer 22 connected in the usual manner with a dust catcher. gas washer. stoves. etc.. not shown. These uptakes and the upper portion of the downcomer are also supported from the top of the shaft of furnace 1.

An auxiliary frame structure 23 is located above and rigidly supported from supporting structure 2; it comprises upstanding legs 24 connected to the supporting structure 2 and carrying a top working platform 25 and a lower working platform 26. the upper end of the skip or belt conveyor bridge. as well as superstructure 27 that supports the repair crane 28 and other parts usually associated with the top of a furnace.

The furnace also includes conventional bustle pipe 29 surrounding the bosh. tuyeres 31. and associated cooling-water collecting trough 32. A working or cast house floor 33 at the lower end of the furnace carries the iron runners 34 extending away from the iron notches 35 and a slag runner 36 extending away from the slag notch 37 in the furnace hearth. This floor is preferably supported independently of the legs 14 of the furnace structure.

In the supporting structure 2. the frame 12 of the illustrated apparatus is made up of four deep steel beams 38 that are welded or bolted at their ends to form a square in plan FIG. 3). Each of the illustrated beams. which may be about l0 feet deep, is an l-section girder having a wide vertical web or wall 39. top and

bottom flanges

40 and 41. and reinforcing stiffeners 42 (FIG. 1); it may be coventionally fabricated. as by welding. from steel plates. The four legs [4 are rigidly connected to frame 12 at the four corners thereof. as by welding or bolting.

At each of eight points of equal deflection on the frame 12. a connector member 43 connects the adjacent l-beam 38 to the blast furnace shell 6 in'the vicinity of the juncture of the shaft and bosh portions of the furnace. preferably at a location such that when the furnace is empty or filled the center of gravity of the furnace is below a horizontal plane containing the center of gravity of the frame 12.

Each of these connector members 43. as shown in FlGS. l to 4. comprises a flat member. preferably formed of thick steel plate. that extends inwardly from the web 39 of the associated l-beam 38 of the frame 12 to the shaft portion 7 of the furnace shell 6 and is rigidly fixed. as by welding or bolting to both the l-beam and the furnace shell. These members 43 are essentially located in spaced vertical planes that extend essentially radially of the furnace shell and pass through and are equiangularly spaced about a vertical axis A" that is essentially coincident with the vertical axis of the furnace of supporting structure 2. The lower portion of each member 43extends downwardly from the bottom of the l-beam 38 to a structural ring 13 located a substantial distance below the bottom. of beam 38 and fixed to the shell 6 of the furnace at the juncture of shaft shell portion and the bosh jacket 8. Preferably. as shown in FIG. 4. a structural ring 45 is fixed to the shell 6 and the inner edge of each member 43. at a location on the shell below the top of frame 12; ring 45 is made of a radially-extending web 46 that is welded or bolted to the shell and members 43. and a stiffening flange 47 that is welded to the web. Rings 13 and45 are also laterally stiffened by numerous reinforcing gussets 48a and 48b (FIGS. 1 and 4) welded to the shell and the rings. if desired. each connector member 43 can be made in two pieces 43a and 43b that are joined along line 50 to facilitate erection. Upper piece 43a can be fixed to supporting frame 12. and lower piece 43b can be attached to the furnace shell 6, after which these parts of each member 43 can be welded together in the field. Members 49 are also fixed, as by welding, to the outer edges of connector members 43 and aid in reinforcing them.

A compression ring member 51. shown in the illustrated embodiment as octagonal with sides of equal length and equal angles between the sides. is fixed. as by welding. to top flanges 40 of the l-beams 38 of the main frame 12. and has intemallyextending projecting portions 52 that are welded orotherwise rigidly fixed to the outer top edges of the connector members 43. This ring member 51 .resists tilting of the beams 38 about their longitudinal generally horizontal axes. from the weight of the furnace or from expansion of the furnace shell on heating. As the furnace heats and its shell increases in diameter, the lower ends of the connector members 43. which are deep enough so they themselves do not appreciably deflect. tend to move outwardly with the lower portion of the shaft shell portion 7 to which is affixed one generally vertical edge of each connector. This causes the upper ends of connectors 43 to tend to move inwardly. which tends to cause the beams 38, to which are fixed the other spaced. generally vertical edges of connectors. to twist about their longitudinal axes so their upper flanges 40 tend to move closer to the furnace than their lower flanges 41. However, any tendency of each l-beam thus to twist or tilt is resisted by the ring member 51 that is thus subjected to compressive forces. Reinforcing members 49. on each side of each connector member 43, also strengthen members 43 against buckling. Since the ring member is a symmetrical polygon with straight sides at the junctures of which the connectors are located. the member is exceptionally efficient in resisting the forces to which it is subjected.

There is a pair of divergent adjustable struts 53 connecting each of the four sides of the frame 12 to the shell (FIG. 3). These struts are turnbuckle-types adjustable as to length. The struts of each pair are pivotally connected to widely spaced lugs 54 on the furnace shell 6 essentially equidistant from the midpoint of the adjacent frame beam 38. and to lugs 55 on the web of such beam at locations closely adjacent to and essentially equidistant from its midpoint. preferably. nearer the top of the beam than the bottom; these struts are generally tangential to shell 6.

At the upper portion of the furnace pairs of divergent ad justable struts 56 similar to struts 53. extend between the top of the furnace shell and the auxiliary frame structure 23 (FIG 5 Struts 56 ofeach pair are pivotally connected to lugs 57 on the furnace shell 6 and to lugs 58 on the adjacent girder 59 forming the top of the auxiliary frame 23, which is made strong enough to resist substantial lateral forces.

Lugs

57 and 58 for each pair of struts are located essentially equidistantly from the center of the associated girder 59, below the top plat form 25, and each strut 56 is generally tangential to the furnace shell.

By suitable adjustments of the lengths of struts 53 and 56 it is possible to cause them to center the furnace in the supporting structure formed of structure 2 and its attached auxiliary frame structure 23, to prevent twisting of the furnace in such structure. and to restrain the furnace against lateral movement relative to such structure in the event of seismic or other shocks, all without preventing vertical movements of the furnace or portions thereof relative to such structure as might result from thermal expansion or contraction. The furnace is thus supported at all times by a strong, stable supporting structure.

ln this embodiment. the shaft of the furnace is cooled by generally horizontal conventional cooling plates 60, extending transversely around the circumference of the furnace in shaft inwall 61, through which plates water is circulated by conventional means. The bosh may be conventionally cooled by water applied to its exterior.

The bottom portion 62 (FIGS. 1 and 2) of the hearth jacket 9 portion of shell 6 preferably is essentially the shape of a hemiellipsoid having a circular cross section, and is lined with a suitable refractory material such as a substantially uniformly thick layer 63 of carbon; the carbon lining in this embodiment continues upwardly at 64 throughout the hearth portion and the bosh up to the shaft inwall 61. The lower portion of the hearth is filled with refractory material, such as carbon or high temperature refractory brick, to form a massive bottom 65. The hemiellipsoidal shape of this portion of the hearth jacket is such that downwardly-acting forces on body 65, resulting from the weights of the liquid metal and the charge material resting on the metal, cause substantially uniform outwardlydirected pressures on the

portions

63 and 64 of the lining and the portions of jacket 9 that enclose and support the body 65. THis hemiellipsoidal shape also minimizes distortion of the material of body 65 on heating and cooling.

Since the hearth portion of the furnace is suspended completely free of any bottom support, numerous advantages result. The hearth portion can be cooled more readily than in conventional furnaces because of the large additional cooling area of the exposed bottom. The vertical and horizontal principal stresses in the hearth and bosh jackets are both tension stresses, so that shear in the steel jackets and their refractory linings is low; this eliminates most if not all the premature lining failure that occurs at these locations in conventional furnaces, in which the hearth and bosh support upper portions of the furnace, from the substantial shear developed in the jackets and lining material because of large horizontal ring stresses. Moreover, the suspended hearth portion facilitates repairing or replacing the lining of the furnace, with considerable savings in labor and time, and considerable reduction in furnace downtime, because accessibility is considerably greater than in conventional furnaces, and it is not necessary to dismantle large amounts of auxiliary equipment at the lower portion of the furnace as is conventionally necessary. Thus, it is a relatively simple matter to cut an opening in the wall of the furnace at floor 33 and move in men and equipment, including highly automated equipment, for relining purposes. The suspended design provides particularly important advantages in relining the lower inwall, bosh and hearth portions that most often require repair or replacement of lining. lt is also possible to remove the entire lower hearth portion of the furnace, with the bosh portion if desired, and replace it with a prefabricated lined replacement portion by use of suitable jack-type dollies; it is merely necessary to attach such replacement portion to the furnace and reline a narrow belt of refractory material at the joint.

Added advantages in strength and stability of support are provided if, before loading, the supporting structure 2 is prestressed and preformed to cause it to be formed and deflected prior to loading so that there is little if any appreciable deflection visually apparent after the furnace structure is completed. Preferably the legs 14 and also the beams 38 of the structure 2 are thus prestressed, and each beam 38 is built with a calculated camber when unloaded, so that each leg has no moment when subjected to maximum loading, and so that each beam is essentially flat when subjected to maximum load- FIG. 6 shows diagrammatically the shapes of the beams 38 and legs 14 of a supporting structure 2 embodying the invention when the structure 2 is prestressed but not loaded, and when the structure 2'is loaded with the weight of the furnace and other structure carried by the furnace. The full lines show, with great exaggeration of curvature for the sake of clearness, the shape of the structure 2 from its side when the legs 14, fabricated to have straight axes, are prestressed and curved by having the lower ends of their outer legs forced outwardly radially from the axis A of the structure 2 and the furnace, to the positions they are calculated to assume under full load. The beams 38 are also shown in full lines as cambered upwardly when the legs are prestressed. Although it might be expected that each beam would be deflected downwardly at its central portion because of the forces exerted on the ends of the beam by the rigid connections of the tops of the legs 14 to the beam ends, in the illustrated embodiment each beam 38 is fabricated so it has an upward cambered curve essentially identical to the calculated deflection that will occur when the beam is loaded with its share of the weight of the furnace and other structure supported by beams 38; therefore the prestressing of the legs 14 will deflect the beam sufficiently to remove part, but not all, of the upward camber of beams 38. Beams 38 and legs 14 are preferably so designed, and the prestressing of the legs is such, that after the structure is fully loaded there is no visually appreciable deflection of the legs and beams so that, as shown by broken lines of FIG. 6, the legs and the beams are straight and can develop their maximum strength.

FIGS. 7 and 8 show means for moving the lower ends of the legs radially outwardly to prestress them as described above, and to hold the ends in such position while allowing the lower ends of said legs to rotate freely, without subjecting the lower ends of the legs to bending moments. This means comprises a metal base member 66, fixed as by bolting to each foundation member 15 set into the earth; the upper surface of this base member is normal to the axis B of the leg 14 when the leg is straight. An adjustable member 67 rests on member 66; it has an upwardly-open annular groove 68, against the bottom and inner wall 69 of which is fixed an annular bearing ring 71 of hardened metal providing an upwardly facing seat 72, spherical about point P. The outer wall 73 of the groove 68 extends upwardly to provide a raised guard and guide.

The lower end of each leg 14 is tapered at 74 as shown and terminates in a casting 75 of thick cross section in which is fixed a seat 76 of hardened metal and shaped to mate with spherical seat 72. Casting 75 has a flange 77 that extends into the groove 68 adjacent outer wall 73; consequently the lower end of the leg 14 is prevented from moving laterally off the seat 72 or jumping off the base in the event of seismic shock or other large disturbances.

To draw the lower end of each leg outwardly to the desired prestressing position, each member 67 is provided with two diametrically spaced lugs 78, each connected by a drawbolt 79 to a lug 81 fixed to the base. By tightening the nuts 82 on bolts 79 the desired amounts, each member 67 supporting the bottom of a leg 14, can be moved from an initial position shown in broken lines in FIG. 8 to its prestressing position shown in full lines in such figure without subjecting the leg to bending moment at its lower end, after which locking blocks 83 can be fixed. as by welding. to the base member 66 to hold the lower end of the leg in the desired prestressing position to provide the above described desirable results The furnace of FIG. 9 includes a supporting structure 2 like that of FIGS l3 including deep l-girders 38 joined at their ends to form a frame 12. that is square in plan configuration. that surrounds and is spaced from furnace 85, and that is supported from its corners by widely spaced legs 14 that. as in the previous embodiment. are prestressed during erection. This frame 12 is connected to the shell 86 of the furnace by radially-extending equiangularly spaced connector members 43 identical with. and fixed to the frame 12 and furnace shell by the same means as, connectors 43 of FIGS. 1-5. A compression ring member 51 and adjustable struts 53 at frame 12, and adjustable struts 56 are also provided to connect the top portion of the furnace to girders 59 of auxiliary frame structure 23. as in the previous embodiment. to perform the same or similar functions. in the embodiment of FIG. 9, however, the hearth portion 87 of the furnace is supported from beneath by a foundation 88 that is set into the earth. The hearth portion may be conventional in design. The remainder of the furnace structure of FIG. 9 may be identical with that of FIGS. 15, inclusive. and like parts bear like reference numerals. No further description is believed necessary.

FIG. shows to a larger scale alternative means for supporting furnace 85 of FIG. 9 from supporting structure 2, and alternative cooling means. The furnace shell 89 in this case is conventional and includes a shaft shell portion 91 and a bosh jacket 92 joined at a mantle ring 93. The square frame 12 of the furnace supporting structure 2 is identical with that of FIGS. 1-4, being made of deep section I-girders 38 that are connected together at their ends. This frame surrounds the furnace and is supported at the four corners by four legs 14, of which one is shown in FIG. 10. The frame is connected to the furnace shell by connector members 94 that, as in the previous embodiment, are equiangularly radially disposed about the shell in essentially vertical planes. These connectors are con nected to the beams 38 forming the frame 12 at points of equal deflection of the beams. Each connector member 94 is deep and stiff in a generally vertical direction, preferably formed of steel plate; it is fixed to the web 39 and the insides of the

flanges

40 and 41 of its associated I-beam 38, and to the furnace shell by being fixed to mantle 93, and to a radiallyprojecting lug or flange 95 fixed to shell 89 by a bolted joining strip 96. Stiffening lugs 97 are preferably fixed to the mantle for added strength. A ring member 98, preferably of equalsided, equiangular, octagonal plan shape like ring member 51 of FIGS. l-4, is fixed to the top flanges 40 of the beams 38 forming frame member 12 in the same manner and location as ring member 51. A similar ring member 99 is similarly fixed to and located on the bottom flanges 41 of the beams 38.

The furnace of FIG. 10 also has generally horizontally-extending conventional cooling plates 101 in the bosh section, through which plates water is circulated by conventional means. The shaft of the furnace is cooled by hollow cooling staves 102, 103, formed of iron or other suitable metal and extending transversely along the circumference of the furnace in the inwall 104; water is circulated through the staves by conventional means. The upper staves 102 are conventional in that they are of rectangular cross section; the lower staves 103 differ in that the upper portion 105 of each stave is considerably wider than its lower portion 106; preferably its exterior top width is about twice its exterior bottom width. This stave shape causes the load resulting from the weight of the brick work or other material forming the inwall 104 of the shaft to be carried down into the reentrant corner between the shaft shell portion 91 and the inwardly-extending portion of mantle 93; this occurs because the material forming the inwall bears on the inwardly-projecting wider upper portions of these lowermost staves to urge these staves downwardly into such comer to distribute the load through the lining material located outwardly of these staves, to the mantle and adjacent portion of the shell.

The design of FIG 10 permits independent assembly of the supporting structure 2 and connector members 94. independent assembly of the shell 89, and subsequent joining of the connector members 94 to the shell by strips 96. In this embodiment. moreover. the

ring members

98 and 99 at the tops and bottoms of beams 38 of the frame 12 resist tilting of the beams from the weight of the furnace or thermal expansion or contraction of the furnace shell on heating or cooling of the furnace. The remainder of the furnace structure illustrated by FIG. 10 may be like that of FIG. 9.

In the modification of FIG, 11 shown as applied to the furnace of FIG 9, the furnace'85 comprising shell 107 is supported from a supporting structure 2 identical with that of FIGS. 1-4, comprising a frame 12 that is supported by legs, not shown, like the widely spaced legs 14 of the previous embodiment. As in the previous embodiment. four deep I-girders 38 are joined aT their ends to define a frame 12 that is square in plan. At points of equal deflection on the frame 12 and equiangularly spaced around the furnace shell there are radially-extending deep, stiff, generally vertical connector members 108 formed of steel plate that are fixed to the webs 39 of the beams 38 of frame 12, as by welding or bolting, and that are rigidly connected to the furnace shell above the mantle by connector strips 109 bolted to members 108 and to radiallyextending lugs 111 fixed to the shell.

In the supporting structure, there is a ring member 112 which preferably is identical to member 51 of FIGS. l- -4, inclusive, and to member 98 of FIG. 9 in that it is of equal-sided, equiangular octagonal shape in plan, fixed to the tops of upper flanges 40 of the beams of the frame 12. Another preferably identical ring member 113 is similarly fixed to and located on the undersides of the bottom flanges 41 of the beams 38.

In this embodiment, conventional generally horizontally-extending cooling plates 114 are provided, through which cooling water is circulated in the usual manner.

The

ring members

112 and 113 stabilize the frame 2 and the furnace shell in the same manner as do corresponding members in the structure of FIG. 6 by preventing harmful tilting of beams 38 of frame 12. Preferably. adjustable struts are provided, of the type and location of struts 53 and 56 of the embodiment of FIGS. l5, to perform the same functions. The remainder of the apparatus, not shown, may be identical with the apparatus of FIG. 9. l

The furnace structures illustrated in each of FIGS. 9, 10 and 11 provide many of the advantages indicated above in connection with the furnace structure of FIGS. 1-8 as arising from improved accessibility to the lower portion of the furnace because of the widely spaced legs, although it does not provide the advantages arising from the suspended hearth, such as rapid replacement of the suspended hearth as a whole, unimpeded downward expansion, and increased cooling area. However, in the structures of FIGS. 9 to 11, the supporting structure 2 formed of the frame 12 and the legs 14 can be designed to be stiff enough to support the load of the furnace above the connector members connecting the frame 12 to the furnace shell, but limber enough so that if the portion of the furnace below the connectors contracts on cooling, the supporting structure can permit sufficient downward movement of the upper portion of the furnace to permit the lower and upper portions of the fumace wall in the vicinity of the'mantle to remain an essentially continuous wall, and thus eliminate the necessity for an expansion joint that is often located near the mantle in conventional furnaces, which expansion joint is often a source of trouble. i

In the embodiment of FIGS. 1 to 8, the entire weight of the furnace and structure supported by the furnace is supported by structure 2. This, therefore, completely avoids the previously discussed problems arising in conventional American and European furnaces because the portions of the furnace above the bosh must be supported by the hearth and bosh portions, since in this embodiment the hearth and bosh are not supporting elements.

In each of the embodiments of FIGS. 9 to II. inclusive, supporting structure 2 is so designed that at least about 25 percent. and preferably 50 percent or even more, of the weight of the furnace above the connections of the fumace above the bosh to frame I2 is at all times carried by the supporting structure 2. even when the furnace is hot and the hearth and bosh portions lengthen to positions where otherwise they would support the portion of the furnace above the bosh. Therefore. the hearth and bosh portions need not be designed to carry as much weight as in conventional American or European blast furnaces. and this substantially minimizes and can eliminate most if not all of the problems described above as arising in conventional furnaces because the hearth and bosh portions must support essentially all of the weight of the furnace and apparatus above the bosh.

Preferablyv in each of the previously described embodiments, the legs 14 of the supporting structure 2 are hollow and are filled with poured concrete introduced by conventional apparatus and methods through openings 120 (FIGS. 3, 4 and in the upper ends of the legs 14. Preferably the concrete 121 extends essentially from the bottom of each leg as shown in FIG. 7 to the upper end of each leg as shown in FIGS. 4 and 10, to insure that when hardened the concrete extends throughout at least the portion of each leg that is subject to deflection. If desired, as shown in FIGS. 7 and 8, reinforcing steel I22 may be embedded in the concrete I21. Preferably the concrete is of the type that does not shrink, or that may even expand slightly, on curing to insure permanent firm contact of the concrete with the inner walls of the legs Maximum benefits are provided when the hollow legs 14, while empty of concrete. are, prior to loading of supporting structure 2, first prestressed by having their lower ends moved outwardly from their initial unstressed position in a direction and by an amount essentially corresponding to the direction and amount that the lower end of each leg would move outwardly from its unstressed position if the supporting structure 2 of which the leg forms a part was subjected to a load corresponding to the furnace, so that the legs are deflected as indicated by the full lines in FIG. 6, the lower ends of the legs being then locked in such positions; structure 2 is then loaded with the furnace so the legs 14 assume positions in which they are essentially undeflected as shown in broken lines in FIG. 6 and in full lines in FIGS. 1, 2 and 9 in which the legs are shown straight; and the legs are thereafter filled with poured concrete which is then allowed to solidify.

The concrete. after it has hardened and cured, stiffens the legs 14 and acts to maintain them in their undeflected conditions, in which they have their maximum strength. This is particularly important since the frame structure as initially designed has deep, stiff cross beams 38 and legs 14 which, while strong enough to support the load of the furnace even before the addition of the concrete, are relatively limber since they are made of steel and capable of being deflected in the prestressing operation. Addition and curing of the concrete while the legs are in their straight or undeflected positions increases the stiffness of the legs and their resistance toward bending.

The concrete in the legs also adds substantial mass to the legs which are of relatively large cross section and considerable length; for example, if the legs are circular in cross section they may be as much as 5 feet or even more in diameter for a furnace of modern large capacity. This large added mass and the resistance of the concrete to compressive forces provides added protection against damage from impacts on the legs, such as might occur from a derailed railroad car, thus adding to the safety of the furnace structure. The added mass of the concrete also acts to substantially absorb and dissipate the energy of either steady or transient vibrations to which the legs 14 or the furnace structure as a whole may be subjected, thus damping out vibrations which could otherwise be harmful. Steady vibrations could occur from operation of sifting machinery or unbalanced equipment which could cause undesirable resonance; transient vibrations could occur from seismic shocks or passing railroad rolling stock. The damping action of the large mass of concrete in each leg prevents undesirable resonance or harm from such vibrations.

The concrete in each leg can also act as a high capacity heat sink that can absorb and transmit away from a point of localized exposure on the leg heat from hot metal. slag or coke that might approach or contact the legs in the event of a furnace breakout. The concrete thus provides added protection for the legs in this respect.

The above advantages of the concrete filling are provided if the legs are of circular cross section as shown. or of other hollow cross sections including polygonal cross sections such as a square cross section.

It is apparent that various modifications can be made in any of the furnace structures illustrated. For example. the furnace tops in FIGS. 1. 2 and 9 could be supported from the auxiliary supporting structure 23, instead of from the top of the furnace shaft, although when the top is supported on the furnace as in the illustrated embodiments advantages arise because the top can move upwardly and downwardly as the furnace shaft expands and contracts. The connector means of FIGS. 10 and I1 could be used in the structure of FIGS. 1-8, as well as in the structure of FIG. 9.

While four legs of circular cross section are shown, one each corner of a four-sided supporting frame, supporting frames of different shapes, preferably polygonal, supported by a different number of legs may be used, and the legs may be of circular or other, even polygonal, cross section. In any event the number and cross section of the legs should be such that adequate support and stability are provided. It appears that for most, if not all. uses four legs and a square-sided supporting frame are most advantageous from the standpoint of stability, adequate support, economy and cost. The legs in the illustrated embodiment are diagonally inclined, for increased stability of the furnace structure; however, they may be vertically disposed, if desired.

Other modifications will be apparent to those skilled in the art. It is intended that the patent shall cover, by suitable expression in the appended claims, whatever features of patentable novelty reside in the invention.

We claim:

1. Shaft furnace apparatus comprising a furnace shall having upstanding sidewall means, and a supporting structure for the furnace comprising a frame surrounding and spaced from said shell and said sidewall means and including generally horizontally disposed frame member means of substantial depth and having a side facing said shell, spaced legs supporting said frame, a plurality of connector means fixed to said side of said frame member means and to said upstanding sidewall means of said shell and extending through the space between said frame and said shell to support said shell from said frame, and means connected to said frame and not affixed to said shell to resist tilting of said frame member means about generally horizontal axes thereof.

2. The apparatus of claim I in which said connector means are fixed to said frame member means at locations of essentially equal deflection on said frame member means.

3. The apparatus of claim 1 in which said connector means extend essentially radially of said shell and are disposed essentially equiangularly around said shell.

4. The apparatus of claim 1 in which said means connected to said frame to resist tilting of said frame member means comprises ring means fixed to the upper portions of said frame member means above the locations at which said connector means are fixed to said frame member means.

5. The apparatus of claim 1 in which said means connected to said frame member means to resist tilting of said frame comprises first ring means fixed to the upper portion of said frame member means above the locations at which said connector means are fixed to said frame member means, and second ring means fixed to the lower portion of said frame member means below the locations at which said connector means are fixed to said frame member means.

6. The apparatus of claim 1 comprising members adjustable as to length connecting said furnace shell to said frame to assist in centering said shell relative to said frame.

7. The apparatus of claim 1 in which said connector means are fixed to said shell to support said furnace aboyc its center of gravity.

8. The apparatus of claim I in which the lower portions of said connector means where they are fixed to said frame are above the lower portions of said connector means where they are fixed to said shell sidewall means 9. The apparatus of claim 1 in which said supporting structure constitutes essentially the only support for said furnace and the lower end of said furnace is suspended from said supporting structure and unsupported from below.

10. THe apparatus of claim 9 in which the bottom of said furnace is essentially hemiellipsoidal.

H. The apparatus of claim 1 in which at least 25 percent of the weight of the furnace above the locations at which said connector means are fixed to said furnace shell is at all times supported by said supporting structure.

12. The apparatus of claim 1 in which said frame is formed of four beams each having a generally vertical wall of substantial depth, said beams being joined to form a frame that in plan is of essentially square configuration and that surrounds and is spaced from said shell. in which apparatus said legs support said frame at the corners of said frame, and in which apparatus said connector means comprises generally vertical members fixed to and extending essentially radially of said shell and fixed to said walls of said beams at points of essentially equal deflection of said beams.

13. The apparatus of claim 12 in which said means resisting tilting of said frame members comprises a ring member fixed to the upper portions of said walls of said beams.

14. The apparatus of claim 12 in which said means to resist tilting of said frame members comprises a ring member fixed to the upper portions of said walls of said beams and another ring member fixed to the lower portions of said walls of said beams.

15. Shaft furnace apparatus comprising a furnace having a hearth portion and a shell having a sidewall portion and a lower portion that encloses said hearth portion; supporting structure for the furnace comprising a generally horizontally disposed frame surrounding and spaced a substantial distance from said sidewall portion of said shell entirely around said shell, legs supporting said frame and spaced from said furnace and from each other, said legs being diagonally inclined relative to said furnace at substantial angles from the vertical with the bottoms of said legs spaced outwardly a substantial distance from the tops of said legs to provide substantial stability for said frame and said furnace, means spaced around said shell and connected to said sidewall portion of said shell and to said frame and extending between said frame and said shell for supporting said furnace from said frame so the hearth portion of said furnace is suspended below said frame and is essentially unsupported from below and so said spaced means supporting said furnace from said frame are connected to said sidewall portion of said furnace shell above the center of gravity of said furnace, and means, independent of said means for supporting said furnace from said frame, connected to said furnace and said frame for restraining said furnace against lateral movement relative to said frame.

16. The apparatus of claim 15 in which the bottom of said furnace is essentially hemiellipsoidal.

17. The apparatus of claim 15 in which the sidewall of the shell is essentially free of sharp bends that could substantially impair the strength of said sidewall for suspending the suspended portions of said furnace.

18. Apparatus of claim I in which said means connected to said frame to resist tilting of said frame member means com prises ring means that is polygonal in plan with straight side membersjoincd at the locations of essentially equal deflection on said frame member means. v

19. Apparatus of claim 2 in which said means connected to said frame to resist tilting of said frame member means comprises ring means that is polygonal in plan with straight side membersjoined at the locations ofessentially equal deflection on said frame member means.

20. Shaft furnace apparatus comprising an upwardly extending furnace, supporting structure for said furnace comprising an essentially rigid generally horizontally disposed frame surrounding and spaced from said furnace, means supporting said furnace from said frame, and means located between said frame and said furnace for restraining said furnace against lateral, movement relative to said supporting structure comprising tension members connected to said furnace and said frame and extending generally tangentially to said furnace.

21. The furnace of claim 20 in which said tension members are adjustable as to length.

22. Shaft furnace apparatus comprising an upwardly extending furnace, supporting structure for said furnace comprising an essentially rigid generally horizontally disposed frame surrounding and spaced from said furnace, said frame being made up of a plurality of beam members that are essentially equal in length and rigidly connected together to define in a plan a symmetrical polygon means supporting said furnace from said frame, and means located between said frame and said furnace for restraining said furnace against lateral movement relative to said supporting structure, saidrestraining means comprising two elongated members connected to each of said beam members and to said furnace shell and extending tangentially to said shell in generally .opposite directions.

23. Shaft furnace apparatus comprising an upwardly extending furnace, supporting structure for said furnace comprising an essentially rigid generally horizontally disposed frame surrounding and spaced from said fumace,said frame being made up of four members of generally equal length to form a frame that is essentially square in plan configuration, means supporting said furnace from said frame, and means located between said frame and said furnace for restraining said furnace against lateral movement relative to said supporting structure, said restraining means comprising tension members connected to said furnace shell and to each of said frame members at essentially the central portion thereof.

24. Shaft fumace'apparatus comprising an upwardly extending furnace, supporting structure for said furnace comprising an essentially rigid generally horizontally disposed frame surrounding and spaced from said furnace, means supporting said furnace'from said frame, means located between said frame and said furnace for restraining said furnace against lateral movement relative to said supporting structure, essentially rigid upper supporting structure surrounding and spaced from said furnace and extending from said first-mentioned supporting structure upwardly adjacent the upper portion of said furnace, and means located between said furnace and said upper supporting structure for restraining said furnace against lateral movement relative to said upper supporting structure comprising tensionmembers connected to said upper supporting structure and said furnace and extending generally tangentially to said furnace.

25. The apparatus of claim 24 in which said tension members are adjustable as to length.

Claims

2. The apparatus of claim 1 in which said connector means are fixed to said frame member means at locations of essentially equal deflection on said frame member means.

7. The apparatus of claim 1 in which said connector means are fixed to said shell to support said furnace above its center of gravity.

8. The apparatus of claim 1 in which the lower portions of said connector means where they are fixed to said frame are above the lower portions of said connector means where they are fixed to said shell sidewall means.

9. The apparatus of claim 1 in which said supporting structure constitutes essentially the only support for said furnace and the lower end of said furnace is suspended from said supporting structure and unsupported from below.

11. The apparatus of claim 1 in which at least 25 percent of the weight of the furnace above the locations at which said connector means are fixed to said furnace shell is at all times supported by said supporting structure.

12. The apparatus of claim 1 in which said frame is formed of four beams each having a generally vertical wall of substantial depth, said beams being joined to form a frame that in plan is of essentially square configuration and that surrounds and is spaced from said shell, in which apparatus said legs support said frame at the corners of said frame, and in which apparatus said connector means comprises generally vertical members fixed to and extending essentially radially of said shell and fixed to said walls of said beams at points of essentially equal deflection of said beams.

18. Apparatus of claim 1 in which said means connected to said frame to resist tilting of said frame member means comprises ring means that is polygonal in plan with straight side members joined at the locations of essentially equal deflection on said frame member means.

19. Apparatus of claim 2 in which said means connected to said frame to resist tilting of said frame member means comprises ring means that is polygonal in plan with straight side members joined at the locations of essentially equal deflection on said frame member means.

20. Shaft furnace apparatus comprising an upwardly extending furnace, supporting structure for said furnace comprising an essentially rigid generally horizontally disposed frame surrounding and spaced from said furnace, means supporting said furnace from said frame, and means located between said frame and said furnace for restraining said furnace against lateral movement relative to said supporting structure comprising tension members connected to said furnace and said frame and extending generally tangentially to said furnace.

22. Shaft furnace apparatus comprising an upwardly extending furnace, supporting structure for said furnace comprising an essentially rigid generally horizontally disposed frame surrounding and spaced from said furnace, said frame being made up of a plurality of beam members that are essentially equal in length and rigidly connected together to define in a plan a symmetrical polygon means supporting said furnace from said frame, and means located between said frame and said furnace for restraining said furnace against lateral movement relative to said supporting structure, said restraining means comprising two elongated members connected to each of said beam members and to said furnace shell and extending tangentially to said shell in generally opposite directions.

23. Shaft furnace apparatus comprising an upwardly extending furnace, supporting structure for said furnace comprising an essentially rigid generally horizontally disposed frame surrounding and spaced from said furnace, said frame being made up of four members of generally equal length to form a frame that is essentially square in plan configuration, means supporting said furnace from said frame, and means located between said frame and said furnace for restraining said furnace against lateral movement relative to said supporting structure, said restraining means comprising tension members connected to said furnace shell and to each of said frame members at essentially the central portion thereof.

24. Shaft furnace apparatus comprising an upwardly extending furnace, supporting structure for said furnace comprising an essentially rigid generally horizontally disposed frame surrounding and spaced from said furnace, means supporting said furnace from said frame, means located between said frame and said furnace for restraining said furnace against lateral movement relative to said supporting structure, essentially rigid upper supporting structure surrounding and spaced from said furnace and extending from said first-mentioned supporting structure upwardly adjacent the upper portion of said furnace, and means located between said furnace and said upper supporting structure for restraining said furnace against lateral movement relative to said upper supporting structure comprising tension members connected to said upper supporting structure and said furnace and extending generally tangentially to said furnace.