US3149827A

US3149827A - Charge support and diffuser assembly

Info

Publication number: US3149827A
Application number: US273630A
Authority: US
Inventors: James L Whitten
Original assignee: Alloy Engineering Co
Current assignee: Alloy Engineering Co
Priority date: 1963-04-17
Filing date: 1963-04-17
Publication date: 1964-09-22
Anticipated expiration: 1981-09-22

Description

Sept. 22, 1964 J. WHlTTEN 3,149,827

CHARGE SUPPORT AND DIFFUSER ASSEMBLY Filed April 17, 1965 2 Sheets-Sheet 1 INVENTOR James L. WHITTEN ATTORNEYS.

Sept. 22, 1964 WHITTEN CHARGE SUPPORT AND DIFFUSER ASSEMBLY 2 Sheets-Sheet 2 Filed April 17, 1963 N TOR.

1 V James L. MZ-l/TTEN 4 TTOENEYS United States Patent 3,149,827 CHARGE SUPPORT AND DIFFUSER ASSEMBLY James L. Whitten, Lakewood, Ghio, assiguor to The Alloy Engineering Company Filed Apr. 17, 1963, Ser. No. 273,630 12 Uaims. (Cl. 263-47) This invention relates generally to heat treating apparatus, and more specifically to a new and improved charge support and diffuser assembly for use in annealing furnaces.

In heat treating coiled metal stock, particularly in bell-type furnaces, it is the practice to support the coils vertically in stacks. The heating of the stacked coils is accomplished largely by convection and, to this end, a suitable fan is provided in the charge supporting structure for circulating a non-oxidizing atmosphere within a mufile or cover which encloses the charge. With this arrangement, the atmosphere flows downwardly through the center of the stack of coils into the fan and is discharged through the supporting structure around the bottom of the charge.

In order to promote optimum efficiency in the circulation of the atmosphere and to reduce unequal heating of the coils and other disadvantages due to turbulent movement of the gases, it is recognized as being desirable to provide a vaned diffuser which will convert the high velocity pressure created by the fan to static pressure. Various attempts have been made prior to this invention to provide a difiuser which will handle the gases efiiciently and which, at the same time, has an economical construction strong enough to withstand the weight of the charge.

One widely known prior art diffuser is comprised of vane assemblies formed of light bars welded together. The welded vane assemblies cooperate to define outwardly diverging gas passages which have inner ends extending spirally from a central opening in the diffuser and enlarged outer ends extending substantially radially. Although this conventional construction is efficient from the standpoint of handling the gases, the bars making up the vanes tend to distort in use and fail to support the weight of the charge. Moreover, the welded vane construction is expensive and difficult to repair.

The present invention overcomes the foregoing and other disadvantages of the prior art, and provides a charge support and diffuser assembly adapted efiiciently to promote good circulation of the atmosphere in furnaces such as described above. In particular, the new and improved diifuser of this invention is adapted to make the best use of gas flow by converting the velocity pressure created by the fan to static pressure, and to reduce turbulence in the gas flow to a minimum by providing for uniform discharge of gas at the periphery of the diffuser. At the same time, the novel diffuser is economically constructed and is designed to provide good support for the heavy furnace charges without Warping or distorting under the high temperature conditions which are encountered. Another feature of the preferred embodiment of the invention is the invention is that those parts of the charge support and diffuser assembly which may be damaged or broken in any way can be replaced and easily repaired.

Other features and advantages of the invention will be apparent from the following detailed description when taken in conjunction with the accompanying drawings.

In the drawings:

FIGURE 1 is a vertical cross-sectional view of a heat treating assembly incorporating the novel charge support and diffuser assembly of this invention;

FIGURE 2 is a top plan view, with portions broken away, of the charge support and diffuser assembly;

3,149,827v Fatented Sept. 22, 1964 FIGURE 3 is a cross-sectional view taken on the line 3-3 of FIG. 2;

FIGURE 4 is a top plan view, with portions broken away and in cross-section of part of the assembly comprising the invention; and

FIGURE 5 is a cross-sectional view taken on the line 5-5 of FIG. 4.

Referring now to the drawings, and to FIG. 1 in particular, the illustrated heat treating assembly includes a charge formed by vertically stacked coils 10 disposed within a mufile 11 which is used to maintain a desired non-oxidizing atmosphere and to promote rapid heating of the charge. The mufile 11 forms part of a conventional bell-type furnace which will be understood to include a surrounding wall 12 that defines a heating chamber. This chamber is usually heated by gas-first radiant tubes (not shown) which may be disposed in the chamher along the sides of the wall 12.

As shown, the furnace also has a steel support base 13 which is surrounded by a ledge 14. The rnufile 11 is supported on the ledge and a seal 15 of suitable material, such as a granular refractory, is formed around the base of the mufile to reduce leakage of the non-oxidizing atmosphere. The furnace base also includes a hole 16 through which extends the shaft of an impeller-type blower fan 17. The fan is disposed below the center opening 18 of the charge and is rotated by a suitable motor (not shown) mounted beneath the base 13.

The new and improved charge support and ditfuser assembly of the invention is indicated generally by reference numeral 25. The fan 17 is positioned centrally within the assembly 25 which rests on the furnace base 13, and, in turn, supports the stack of coils 10. As generally described above, the non oxidizing atmosphere in the muflie flows upwardly along the outside of the coils and downwardly through the center opening 18 to enter the top of the fan. The atmosphere drawn into the rotating fan is then discharged substantially tangentially at a high velocity pressure into the assembly 25 which, as will hereinafter be described in detail, is adapted to convert the high velocity pressure to static pressure, while substantially eliminating turbulent gas fiow.

In order to improve the circulation of the atmosphere and effect substantially uniform heating of the charge, separator or convector plates 26 are provided between the coils 10 and between the lower coil of the charge and the assembly 25. As shown in FIG. 1, each of these separator plates 26 defines radially extending gas channels opening alternately upwardly and downwardly, thus providing large areas of gas contact with the edges of each coil. While other forms of separator plates can be used, the illustrated construction obtains maximum heat transfer to the coil edges, as well as good coil support. As is also shown in FIG. 1, an annular plate 27 having a reduced diameter is placed on the top coil over the opening 18 in order to promote flow of the atmosphere inwardly through the separator plates.

Referring now to FIGS. 2 and 3, the improved charge support and difiuser assembly 25 is shown to comprise an annular base plate 30 to the perimeter of which is secured an upstanding wrapper or rim 31. A plurality of spaced diffuser vanes 32 are secured to the surface of the base plate around its center opening 33. Each of the vanes 32 is generally triangular in the plane of the base plate 30 and has a tapered outer end 34 spaced inwardly of the wrapper, a truncated inner end 35 at the edge of the opening 33, and an apex 36 lying on a circle between the inner and outer edges of the base plate.

In accordance with the preferred form of the invention, the vanes 32 are solid, one-piece members cut from a thick plate. The maximum width of each vane at its apex 36 is preferably greater than one-half its height amass? above the base plate. Because of this construction, the vanes 32 provide a strong, stable support for the coils to be annealed and will not buckle or distort under the load of the charge.

In addition to the val es 32, a plurality of smaller, vane separator members 42 are secured to the base plate at its outer edge between the tapered outer end portions 34 of adjacent vanes. As shown, each vane separator has inwardly converging sides 43 and 44- of unequal length, and an inner end surface The longer side 43 and the end surface 45 are respectively parallel to the confronting sides of adjacent vanes 32. The vanes 32 and the vane separators cooperate to define outwardly diverging gas channels 46 extending at an angle to the radius of the base plate and having outer bifurcated portions 46' and 46". The

branches

46 and 46 extend at an angle to each other and the width of the branches 46 preferably is slightly less than the branch 46.

The illustrated form of the support and diffuser assembly includes holes 4-7 which are formed through the base plate near its outer edge and which are spaced 180 apart. Each hole 47 communicates through the wrapper 31 by means of a pipe 43. One hole is disposed in communication with a gas inlet pipe (not shown) in the furnace base 13 so that the non-oxidizing gas is introduced into the muffle 11 through the sides of the assembly 25. The other hole and the connecting pipe 48 is disposed in communication with a gas outlet pipe in the furnace base (also not shown) and serve as an exhaust outlet for the atmosphere. At the location of the holes 47, the vanes 32 are separated by trianguloid members 49 which are preferably used in place of the vane separators 32.

The preferred construction of the charge support and diffuser assembly of this invention further includes a vane tip assembly 55 which is removably mounted within the center opening 33 of the base plate. As most clearly shown in FiGS. 4 and 5, this vane tip assembly comprises a top ring 56 lying in the plane of the upper surfaces of the vanes 32, a bottom ring 57, and a plurality of vane tips 58. The vane tips are preferably steel castings which are welded between the rings in a symmetrical arrangement.

Each vane tip 53 forms a continuation of the truncated end 35 of one of the vanes 32 and has inwardly converging sides 59, 6%, and a tipped inner portion 61 at the inner edges of the rings d, 57. Thus arranged, the vane tips form throat portions for the gas channels 46, whereby the high velocity pressure atmosphere is discharged from the fan tangentially into the diffuser. As will be apparent from FIGS. 2 and 3, the assembly of the

rings

56, 57 and the vane tips 53 is inwardly spaced from the inner edge of the base plate 3% and the truncated ends of the vanes 32. In order to locate the assembly so that the outer ends of the vane tips are adjacent the truncated ends of the vanes 32, the outer ends of four equally spaced vane tips are provided with projections 61 which are engageable in channels 62 formed in the adjacent truncated vane ends 35.

Referring again to FIGS. 2 and 3, it will be seen that an annular spacer plate as is positioned within the bottom ring 57. The shaft of the fan 17 extends upwardly through the spacer plate and, if desired, an orifice plate 66 may be welded within the spacer plate to receive the shaft. The assembly 25 is completed by an annular support plate 67 which rests on the vanes 32 and the vane tip assembly 55. The center opening of this support plate 67 forms a gas flow inlet to the fan 1'7. The perimeter of the support plate is spaced inwardly of the wrapper 31 to provide an outlet opening 68 for the discharge of the atmosphere from the diffuser around the charge.

The divergence of the gas flow channels 46 from the tangential openings or throat portions defined by the vane tips to the outlet opening 68 of the difiuser assembly and the division of each outwardly diverging channel into angular related branches 46' and 46 is such as to uniformly discharge the gas around the periphery of the diffuser assembly and thereby convert the high velocity gas pressure to static pressure with maximum efiiciency and substantially to eliminate turbulent gas flow. One important feature of the invention is that this efficient handling of the gas is effected by using solid vane formations. As explained above, this construction of the vanes provides optimum support for the weight of the charge and resists distortion when subjected to the high temperature conditions of the furnace. At the same time, the diffuser assembly is more economical and easier to construct than the welded vane assembly diffusers of the prior art.

Still another feature of the invention is that the vane tip assembly 55 can be removed from the furnace independently of the base plate and the main vane bodies 32. This separable construction allows the vane tips easily and quickly to be repaired and replaced should they be damaged in any way without necessitating removal and handling of the entire diffuser assembly.

Many modifications and variations of the invention will be apparent to those skilled in the art in view of the foregoing detailed description. Therefore, it is to be understood that, within the scope of the appended claims, the invention can be practiced otherwise than as specifically shown and described.

What is claimed is:

l. In a diffuser construction, a vane tip assembly comprisin flat top and bottom rings, and a plurality of spaced vane tip formations secured between said rings, each of the vane formations including a base adjacent the outer edges of said rings, inwardly converging sides, and a tip adjacent the inner edges of said rings, said vane tip formations being symmetrically arranged to define outwardly diverging gas passages.

2. In a diffuser assembly, the structure comprising a base plate having a central opening, a plurality of solid, one-piece vanes disposed on said plate and spaced around said opening, said vanes being generally triangular in the plane of said plate and having tapered inner and outer ends, the maximum width of each vane between its ends being at least equal to one-half of its height, and a plurality of vane separators around the outer edge of said base plate and extending between said vanes, said vanes and vane separators cooperating to define outwardly converging gas channels.

3. A charge support and diffuser assembly comprising a plurality of circumferentially spaced vanes having inner ends, said spaced vanes being arranged to form gas channels diverging outwardly from the center of said charge support and diffuser assembly, a centrally disposed, unitarily removable assembly of spaced vane tips, each of said vane tips forming a continuation of the inner end of one of said vanes and being spaced therefrom, said tips cooperating to define throat portions for said gas channels, and said vane tip assembly having a central opening so that a fan can be centrally posi ioned within said charge support and diffuser assembly.

4. The assembly as claimed in claim 3 wherein said vanes and vane tips have side surfaces, and wherein the outer end of each vane tip has a transverse dimension equal to the distance between inward projections of said side surfaces of the adjacent vane so that said side surfaces of said vane tips form continuations of said side surfaces of said vanes.

5. The structure as claimed in claim 3 wherein said vanes include tapered outer ends, and wherein each vane has a maximum width between its ends which is at least one-half of its height.

6. A charge support and difiuser assembly comprising a base plate having an inner edge forming a central opening, a plurality of spaced vanes disposed on said base plate and having inner ends arranged around said open ing, a removable vane tip assembly within said opening,

said tip assembly including a plurality of spaced vane tips each forming a continuation of the inner end of one of said vanes, means securing said tips together as a unitary assembly, the assembly of said tips and securing means being inwardly spaced from the surrounding portions of said base plate and said vanes, and locating means engaging said tip assembly to hold said vane tips adjacent the inner ends of said vanes.

7. A charge support and diffuser assembly comprising in combination:

(a) a base plate,

(b) a plurality of circumferentially spaced vanes arranged on said base plate, each of said vanes being triangular in the plane of said base plate and including a tapered outer end adjacent the outer edge of said base plate, a truncated inner end, and an apex between said ends, and

(c) a removable vane tip assembly disposed centrally of said bottom plate,

(d) said vane tip assembly including a plurality of spaced vane tips each forming a continuation of a truncated end of one of said vanes.

8. A charge support and diffuser assembly comprising in combination:

(a) an annular base plate,

(b) a plurality of solid, one-piece vanes disposed on said base plate in symmetrical, spaced arrangement,

(0) said vanes being generally triangular in the plane of said base plate and including truncated ends at the inner edge of said base plate, outer ends adjacent the outer edge of said base plate, and apexes lying on a circle between the edges of said base plate,

(d) vane separator members disposed around the outer edge of said base plate between the outer end portions of said vanes, said members including inwardly converging surfaces parallel to the confronting side surfaces of said vanes,

(e) a removable vane tip assembly disposed within the center of said base plate,

(f) said tip assembly including a top ring, a bottom ring, and a plurality of vane tips between said rings,

(g) each of said vane tips forming a continuation of the truncated end of one of said vanes and having an outer end at the outer edges of said rings, inwardly converging sides, and a tipped portion at the inner edges of said rings, and

(h) annular spacer means disposed within said bottom ring.

9. A charge support and diffuser assembly comprising in combination:

(a) an annular base plate,

(b)a circumferential wrapper adjacent the periphery of said base plate,

(0) a plurality of solid, one-piece vanes disposed on said base plate in symmetrical, spaced arrangement to define outwardly diverging gas passages,

(11) said vanes being generally triangular in the plane of said base plate and including truncated ends at the inner edge of said base plate, outer ends adjacent said wrapper, and apexes lying on a circle between the inner and outer edges of said base plate,

(e) vane separator members disposed around the outer edge of said base plate between the outer end portions of adjacent vanes,

(7) each of said separator members having inwardly converging side surfaces of unequal length and an inner end surface, said inner end surface and the longer of said side surfaces being parallel to the adjacent surface of said vanes, and

(g) a removable vane tip assembly disposed within the center of said base plate,

(h) said vane tip assembly including a top ring in the plane of the upper surfaces of said vanes, a bottom ring lying in the plane of said bottom plate, and a plurality of vane tips each forming a continuation of the truncated end of one of said vanes,

(1') each of said vane tips having an end at the outer edges of said rings, inwardly converging sides, and a tipped, inner end at the inner edges of said rings, said vane tips being symmetrically arranged to define throat portions of said gas passages.

10. The combination as claimed in claim 9 including an annular spacer plate disposed within said bottom ring.

11. The combination as claimed in claim 10 including indexing means for locating the outer ends of said vane tips adjacent said truncated ends of said vanes.

12. A charge support and diffuser assembly comprising in combination:

(a) an annular base plate,

(b) a plurality of vanes disposed on said base plate in symmetrical, spaced arrangement,

(c) said vanes having inner ends adjacent the inner edge of said base plate and outer ends adjacent the outer edge of said base plate,

(d) a plurality of members disposed on said base plate, said members extending from adjacent the outer edge of said base plate inwardly between said vanes and cooperating therewith to define gas channels, and

(e) a removable vane tip assembly within the center of said base plate, said vane tip assembly being spaced inwardly from the surrounding portions of said base plate and said vanes,

( said tip assembly including a top ring, a bottom ring, and a plurality of spaced vane tips secured between said rings,

(g) each of said vane tips forming a continuation of the inner end of one of said vanes and having an outer end, inwardly converging sides, and a tip portion, whereby said tips cooperate to define throat portions for said gas channels.

References Cited in the file of this patent UNITED STATES PATENTS 2,731,2154 Campbell et al. Jan. 17, 1952 2,815,197 Blackman Dec. 3, 1957 3,039,754 Jones June 19, 1962 3,100,634 Rubrecht et al. Aug. 13, 1963 FOREIGN PATENTS 1,197,727 France Dec. 2, 1959

Claims

1. IN A DIFFUSER CONSTRUCTION, A VANE TIP ASSEMBLY COMPRISING FLAT TOP AND BOTTOM RINGS, AND A PLURALITY OF SPACED VANE TIP FORMATIONS SECURED BETWEEN SAID RINGS, EACH OF THE VANE FORMATIONS INCLUDING A BASE ADJACENT THE OUTER EDGES OF SAID RINGS, INWARDLY CONVERGING SIDES, AND A TIP