US3436063A - Blast furnace shroud - Google Patents

Description

April 1, 1969 W. J. WOODWORTH ETAL BLAST FURNACE SHROUD Sheet of2 Filed March 9, 1967 U.S. Cl. 263-50 13 Claims ABSTRACT F THE DISCLOSURE A protective shroud for covering a damaged bell of a blast furnace, said shroud preferably comprising top and bottom shroud members each having walls which slope downwardly and outwardly when the shroud is installed in a blast furnace.

This invention relates generally to the protection of worn or damaged bells located in blast furnaces and more particularly to providing a protective shroud for placement on top of the damaged bell.

Blast furnaces are conventionally provided with an upper charging chamber having top and bottom openings. The top opening constitutes an entry for the introduction of charging material into the chamber, whereas the bottom opening provides an exit for the discharge of the material from the charging chamber into the blast furnace proper.

A pair of closure members or bells are also conventionally provided, one for each of the openings. The bottom closure member is kept closed when the top closure member is opened for the introduction of charging material into the chamber; and the top closure member is closed when the bottom closure member is opened to discharge the material from the chamber into the blast furnace. The closure members commonly referred to as bells are provided with a bell-shaped configuration for peripherally deecting and distributing charging material descending through the adjacent opening.

Problems arise when, due to a wearing condition or the like, a bell is worn or even perforated. This is particularly hazardous when the hole lis located in the top, small bell, for the gases, under pressure in the blast furnace, escape through the opening in the bell thereby permitting the presence of hot and toxic gases in the area about the blast furnace. This problem is compounded when charging material is deposited upon the top of the small bell for the escaping gas blows charging material away from the bell and the blown material falls to the ground in the general area surrounding the furnace. The presence of the escaping gas and falling material are obvious hazards to the safety of personnel working in the region of the furnace.

The present procedure for rectifying this dangerous situation is to shut down the furnace in order that the damaged bell-shaped closure member be replaced or repaired. The shut down of the blast furnace generally required for replacing a bell is generally quite long and, in some instances, the shut down amounts to eight or more hours. A furnace shut down for this length of time is quite undesirable as this detracts substantially from the furnace output.

The shroud device disclosed and claimed herein serves to minimize the safety hazards and shut down problems presently caused by a blast furnace which has a worn or damaged bell. The protective shroud of the present invention can readily be placed over the `worn or perforated bell by a small crew.

Other features and advantages are inherent in the strucnited States Patent O 3,436,063 Patented Apr. 1, 1969 ture claimed and disclosed, as will become apparent to those skilled in the art from the following detailed description in conjunction with the accompanying drawings wherein:

FIGURE 1 is a diagrammatic vertical sectional view of the upper portion of a blast furnace charging chamber and associated protective shroud constructed in accordance with the present invention;

FIGURE 2 is a perspective view of an assembled protective shroud of the present invention;

FIGURE 3 is a sectional view of the assembled protective shroud according to the present invention taken along line 3-3 of FIGURE 1;

FIGURE 4 is a fragmentary sectional view taken along line 4-4 of FIGURE 1; and

FIGURE 5 is a vertical sectional view of a disassembled half of the protective shroud.

In the illustrative embodiment shown in FIGURE l of the drawings, there is shown the upper part of a blast furnace 10, which, inthe present embodiment, is of the double bell and hopper type. Blast furnace 10 includes closure means in the form of a small upper bell 11 which is adapted to move vertically into and out of seating c0ntact with yits associated distributing upper hopper 12. The small bell 11 is suitably mounted for vertical movement and is supported by a bell rod 13 which is connected at its upper end to a bell rod actuating means, not shown.

The large lower bell 16 is adapted to move into and out of seating Contact with its associated large lower hopper 17. Bell 16 is mounted for vertical movement and is supported by a bell rod 18 lwhich travels within bell rod 13. Rod 18 is connected to a bell rod actuating means, not shown. Abrasion rings 19 surround bell rod 13.

A blast charge is received from a chute, not shown, and enters into upper hopper 12, the charge as it enters hopper 12, falling on the top, frusto-conical shaped wall 21 of small bell or closure member 11. When bell 11 is moved out of seating contact with hopper 12, the charge is permitted to fall into large hopper 17. From hopper 17 the material is subsequently caused to fall directly into the remainder of the blast furnace when bell 16 is moved out of seating contact with large hopper 17.

It can be seen from FIGURE 1 that as charging material falls onto the top surface of wall 21 of bell 11, a wearing problem is created. It has been found that after a period of time, a groove or even a hole will appear on the top surface of wall 21. The adverse effects resulting from a hole in this closure member is apparent, for when bell 16 is opened in a charging operation, hot gases under pressure in furnace 10 rise upward and attempt to escape from the furnace through any opening available to them. The escaping gases will pass through a hole in wall 21 and, being under suflicient pressure, will blow charging materials piled on top of bell 11 up into the air where this material then falls to the ground in the area surrounding the blast furnace.

When such a hole appears or an inspection reveals that the bell 11 is severely worn or damaged, a protective shroud 22 can be installed, readily and economically, on top of surface 21 thereby eliminating deficiencies associated with the damaged bell. Shroud 22 comprises a bot-- tom shroud member 23, upper shroud member 24, and spacing plates 25. In the drawings, shroud 22 is shown constructed of two halves 27, 28 which are fastened together at the conveniently available holes 34 by suitable fastening means, e.g., bolts and nuts 29, 30.

Preferably, shroud member 23 has a frusto-conical shaped wall which substantially corresponds to the sloped or tapered shape of frusto-conical wall 21 of bell 11; however, the shape of this 'wall 31 could be varied, if desired. The length x of shroud member 23 is not critical, it only being necessary to make certain the worn or damaged area of bell 11 is covered to eliminate the gas leakage condition that prevails. Similarly, the shroud should be heavy enough to make certain that any escaping gases will not have sufficient pressure to cause movement of the shroud when it is installed.

The shroud can be fabricated or cast and a layer of hard surface weld 30 is preferably deposited on the top surface of wall 31 for a substantial portion .along the length of the wall as seen in FIGURES 2 and 5 and along the entire surface of wall 43 of upper shroud member 24.

-Ribs 33 are spaced circumferentially about the bottom surface of wall 31 to space shroud 22 from bell 11. The thickness of the ribs is not critical; however, it has been found that a rib thickness of about ll/z" is satisfactory.

Positioned above shroud member 23 is a second shroud member 24 having a frusto-conical shaped wall 43 which is shaped substantially like wall 31 although somewhat less in length. Shroud member 24 is maintained in a spaced position above shroud 22 by means of a plurality of plates 25. Each vertical plate 25 is fastened to the top surface of shroud member 23 and the bottom surface of shroud member 24.

As seen in FIGURES 2, 3 and 5, the smallest, inner circular openings 3S, 36 respectively of each of the shroud members is about the same, these openings in each of the shroud members being slightly larger than the outer diameter of abrasion rings 19 so that upon installation of shroud 22, a loose fit exists between the shroud members 23, 24 and abrasion rings 19 positioned about bell rod 13. Charging material falling about the bells will iill the space between the openings 35, 36 of the bells and rings 19 and the space between the bottom surface of shroud 22 and bell 11.

The length and slope of wall 43 of shroud member 24 is such that it will extend outward beyond cover plates 2S so that charging materials will not fall directly upon the shroud fastening means 29, `30. Additionally the charging materials will have a graduated fall upon upper shroud member 24 and lower shroud member 23 before it comes to rest against wall 21 of bell 11. This impedanceof the fall of charging materials into hopper 12 serves to increase the wear life of the bell 11.

If one desired, the top shroud member 24 could be eliminated; however, it is preferred that this member be retained as it prevents damage to the fastening means 29, 30 employed to connect shroud halves 27, 28` together.

The drawings in the instant application designate the shroud as comprising two halves 27, 218; however, it is appreciated shroud 22 could be made of a larger number of pieces. This would be especially true in the case where a protective shroud is employed with the large bell 16 in which case the shroud would be composed of three or four pieces which could be assembled together in installation.

The foregoing detailed description has been given for clearness of understanding only, and no unnecessary limitations should be understood therefrom, as modifications will be obvious to those skilled in the art.

What is claimed is:

1. A protective shroud for use with a bell in a blast furnace, said shroud comprising:

a shroud member having a wall adapted for seating engagement with said bell when said shroud is installed in said blast furnace and further including a second shroud member positioned above said first recited shroud member; and

spacing means disposed between and connected to the two shroud members.

2. A protective shroud in accordance rwith claim 1 wherein said rst recited shroud member has a frustoconical shaped Wall with a top and bottom surface which slopes outwardly and downwardly when said shroud is installed in said blast furnace.

3. A protective shroud in accordance with claim 2 further including a plurality of spacing means positioned circumferentially about the bottom surface of said wall.

4. A protective shroud for use with a bell in a blast furnace, said shroud comprising two halves, each of said halves comprising:

a first shroud member portion adapted for seating engagement with said bell when said protective shroud is installed in said blast furnace;

a second shroud member portion spaced above said first shroud member portion when said shroud is installed; and,

spacing means disposed between and connected to said first and second shroud member portions, said spacing means having openings therein.

S. In combination with a bell in a blast furnace, a protective shroud disposed on top of said bell, said shroud comprising:

a first shroud member comprising a wall which extends over at least a substantial portion of said bell;

a second shroud member disposed above said first shroud member, said second member comprising a wall with at least the top surface of said wall being sloped downwardly and outwardly;

said wall of said first shroud member having a top surface which slopes downwardly and outwardly and a bottom surface which conforms substantially to the top surface of said wall of said bell;

said second shroud member having a maximum width which is less than the maximum width of said first shroud member; and,

a plurality of spacing plates, each of said plates having two ends, one of said ends being fastened to said bottom surface of said wall of said second shroud member while said remaining end is connected to said top surface of said wall of said first shroud member, each of said plates being vertically positioned and located beneath said wall of said second shroud member; and,

means for fastening said plates together.

6. In combination with the |bell and protective shroud of claim 5, said protective shroud further including means located internally of said first shroud member for maintaining a space between the outer surface of the bell and the inside surface of said rst shroud member.

7. A protective shroud for use with a bell in a blast furnace, said shroud comprising:

a rst shroud member;

a second shroud member;

vertical spacing means for spacing said second shroud member vertically from said first shroud member; and

means on said second shroud member for protecting fastening means, which are located on said spacing means when said shroud is installed on said bell from abrasive materials caused by charging materials.

8. A protective shroud for use with a bell in a blast furnace, said shroud comprising:

a first shroud member having a frusto-conieal shaped Wall with a top and bottom surface, said wall tapering downwardly and outwardly when said shroud is installed;

a second, smaller shroud member positioned above said rst shroud member when said shroud is installed;

said second shroud member having a frusto-conical shaped wall with a top and bottom surface, said wall of said second member being sloped downwardly and outwardly when said shroud is installed;

said second shroud member having a maximum width which is less than the maximum width of said first shroud member; and

a plurality of spacing plates connected to said bottom surface of said second shroud member and said top surface of said first shroud member, said plates being entirely disposed vertically beneath said wall of said second shroud member when said shroud is installed in a blast furnace.

9. A protective shroud in accordance with claim 8, said shroud comprising two halves and said plates having openings therein for receiving fastening means for fastening said halves together when said shroud is installed in a fblast furnace.

10. A protective shroud for use with a bell in a blast furnace, said furnace lbeing adapted to receive falling charging materials that enter said furnace from a hopper positioned above said bell, said shroud comprising:

a frusto-conical shaped shroud wall having an external and internal surface and top and bottom openings; said top opening being substantially smaller than said bottom opening;

a spacing means located on said internal surface of said shroud wall for spacing said shroud from said bell when said shroud is installed upon said bell; and

said top opening of said shroud being sutli'ciently large to permit said charging materials to enter said top opening when said shroud is positioned upon said bell;

whereby said charging materials will become entrapped and packed inthe space between said internal surface of said shroud wall and said bell.

11. A protective shroud in accordance with claim 10, wherein said spacing means comprise a plurality of mem- 'bers spaced from each other and positioned circumferentially about said internal surface of said shroud wall.

12. A protective shroud in accordance with claim 11, wherein said plurality of members comprise ribs.

13. A protective shroud in accordance with claim 10, said shroud comprising two halves joined together.

References Cited UNITED STATES PATENTS 2,559,763 7/1951 Ginder et al. 263-50 3,070,242 12/ 1962 Berczynski 214-36 3,275,310 9/1966 Hanna 266-27 FREDERICK L. MATTESON, IR., Primary Examiner.

E. G. FAVORS, Assistant Examiner.

U.S. Cl. X.R. 214-36; 266-27

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