US2215887A - Method of operating mineral wool furnace - Google Patents

Description

- STEEL SHELL Sept. 24, 1940. w R sElGLE AL 2,215,887

METHOD OF OPERATING MINERAL WOOL FURNACE Original Filed May 4, 193': 2 Sheets-Shed 1 CHARGING DUDE 5M6, ROCK OR OTHER RAW MATERIAL FIRE BRICK WATER JACKET LINING SHELF WATE R TUYERES WATER.

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Patentedsept. 24, 1940 UNITED STATES METHOD OF OPERATING MINERAL WOOL FURNACE William R. Seigle, Mamaroneck, N. Y., and Howard J. OBrien, Plainfield, and George S. Smith, Bound Brook, N. J., assignors to Johnsporat'ion of New York Manville Corporation, New York, N. Y., a cor- Application May 4, 1937, Serial No. 140,640

. Renewed March 1, 1940 13 Claims. (01. 263-52) The present invention relates to a method of operating a melting furnace and more particularly, this invention relates to amethod of charging and operating acupola in the manufacture of mineral wool.

It is an object of this invention to provide a methodof charging and operating a melting furnace to produce-a superior grade of mineral wool on an economical basis, and without rapidly de- 10 teriorating the furnace or cupola.

Other objects of the invention, if not specifically pointed out, will be apparent to those skilled in the artfrom the following detailed descriptions of what are now considered to be the preferred l5 embodiments of the invention.

25 a metallic shell 2 positioned within a water jacket 4. The shell 2 and water jacket 4 comprise the skeleton structure of the cupola, and in the present showing, the water jacket extends from the bottom of the cupola to a point flush with the hot- 30 tom of the charging door 6. The upper limit for the water jacket 4, however, maybe positioned at any point along the shell 2 that may be desired, depending upon the operating temperatures desired within the particular cupola, the tempera- 35 ture of the cooling water desired, and the type of refractory material employed as a lining for the cupola. a

The cupola is provided with bottom doors 8 and a built-up hearth I ther'eabove, both of which 40 may be of conventional design. A conventional notch or outlet l2 (shown in dotted lines) is provided at any desired point in the side wall of the cupola. The cupola wall above the water jacketed area is formed of fire bricks l4, and a cap I6 lead- 5 ing to a suitable stack I8 is carried by the brick wall.

A shelf or supporting member 20 is riveted, welded or otherwise fastened around the interior of the shell 2 at a point which is preferably flush to with, just above or slightly below the upper limit of the combustion zone, within the combustion chamber of the cupola. lower end of the shell 2 define the combustion chamber. The limits of the combustion zone, 55 within the combustion chamber, will vary with The hearth l0 and the the size of the cupola, the air pressure employed for the forced draft, the type of fuel and raw material employed, and other factors generally present in cupola or melting furnace practice. The limits of the combustion zone can be definite- 5 1y determined for any given cupola by controlling these factors, or may be determined by trial with sufficient accuracy to .establish a proper position for the shelf 20.

A lining of fire brick 22 is placed around the 10 inside of the shell 2, supported on the shelf 20, and terminated at any desired point below the charging door 6. A cement cap 24 is usually placed around the top of the lining 22 to provide mechanical protection for the same.

The shelf is preferably welded to the shell so as to establish good contact between the two to insure rapid heat exchange, and to provide a seal between the shelf and shell to prevent gases from entering therebetween.

Tuyeres 26 extend through the water jacket 4 and the shell 22 below supporting member or shelf 20 and adjacent the combustion zone. Any desired number of tuyeres 26 may be employed. The shell 2 around each tuyre 26 may be extended inwardly, as shown at 28, and fit tightly around the end or near the end of the tuyre to provide a water jacket around at least a portion of that part of each tuyre which projects in wardly beyond the major portion of the shell 2. 30

In charging the furnace, or cupola, raw material, which may be slag, rock, or other desired .material, and the fuel, which may be coke, are

charged into the furnace in alternate layers. The fuel in each layer is placed predominantly direct- 1y over the combustion zone, which is usually near the center of the furnace, but extends in most instances generally over the charging area, as shown in Fig. 1. 4

The slag or other raw material is charged into the furnace or cupola with the major portion thereof away from the area directly above the central-portion of the combustion zone, which is usually near the center of the cupola, but extending in, each layer generally over the coke layer, as shown in Fig. 1.

There have been various methods of charging furnaces or cupolas generally used heretofore for melting mineral wool raw material. One of these methods consists in charging the raw material and fuel into the furnace or cupola, whichis lined all the way to the bottom, in alternate layers of substantially uniform thickness measured vertically. Another method heretofore employed consists in charging fuel and raw material into a cupola or furnace, lined all the way to the bottom or hearth, with the fuel in a definite central column and surrounded by the raw material. The present method of charging overcomes inherent weaknesses in all known prior cupola practices. According to the present invention a maximum of surface contact between the raw material and fuel is obtained because of the arcuate surfaces between the layers and the multiplicity of layers present. Also, the majority of the coke is in a position to pass directly into the combustion zone, yet a sufficient amount of the coke or other fuel is dispersed throughout the raw material near the combustion zone to prevent banking or scaifolding of the charge in the cupola above the combustion zone. The gases passing up through the cupola are forced to traverse fuel and raw material alternately and thereby impart sensible heat to the raw material as well as preheat the fuel. In addition, when the fuel and raw material pass into the combustion zone in the present method of charging, there is sufficient fuel intermixed with the raw material to cause efiicient metling of the raw material over a relatively large area, and the wide combustion zone thereby formed causes a large, relatively deep pool H of molten material to be formed at the bottom of the cupola. All of these factors cooperate to produce a clear, free running melt which can be easily controlled and utilized to maximum advantage throughout the remainder of the wool formation operations which may be conventional and need not be described in detail.

By terminating the lining nearthe upper limit of the combustion zone, the expansion which takes place as the charge passes by the lower terminus of the lining causes the charge in and around the combustion zone to be materially loosened and thereby enables air to freely pass through the material of the charge into the combustion area. Since there is very little vertical pressure on the material directly below the lining, the material is very loose at this point and enables air to be passed into the combustion zone by tuyres which terminate without the combustion zone and rapid destruction of the tuyres is thereby prevented. Any air which is deflected vertically by the charge strikes the under side of the lining support 20 and. is further deflected into the combustion zone.

The furnace or cupola illustrated in Fig. 2 is similar to that illustrated in Fig. 1 with the exception of the tuyeres. The tuyres 26' employed in this construction, are separate from the shell of the cupola, and each comprises an air tube 30 surrounded by a water jacket 32 having water inlet and outlet pipes 34 and 36, respectively. Each of the tuyres 26, passes through an opening 38 formed in the shell 2 and water jacket 4, and is sealed by any suitable refractory cement 40, placed between the tuyere 26' and the opening 38.

By this construction adjustable tuyeres are provided which can be made to project into the cupola to any extent desired, and positioned at various points to accommodate particular operations. One of the many positions in which the tuyeres 26' may be placed is indicated in dotted lines for the tuyre on the right hand side of Fig. 2.

When a particularly large cupola or furnace is employed, as shown in Fig. 2, the charging method employed is generally the same as that explained before, except that the coke or other fuel will usually not cover as much of the under-.

lying layer of raw material, but will be pocketed between successive layers of raw material, as shown in this figure.

The method of operation of the cupola shown in Fig. 2, is generally the same as that shown in Fig. 1 and need not be separately discussed.

The foregoing details have been given for the purpose of describing the invention and are not to be considered as limitative, since various modifications may be made therein, all of which fall within the scope of the following claims.

What we claim is:

1. A method of charging a melting furnace, comprising placing alternate layers of fuel and raw material into said furnace with the fuel predominantly above the center of the combustion zone in the furnace but extending to the walls thereof, and with the raw material predominantly around the walls of the furnace but generally covering the fuel.

2. A method of operating a melting furnace comprising forming in said furnace a column including alternate layers of fuel and raw material, with the fuel predominantly above the center of the combustion zone in the furnace but extending to the walls of furnace, and with the raw material predominantly around the walls but extending towards the main 'body of the fuel, abruptly increasing the cross-sectional area of said column near the combustion zone, and circulating air through the charge subsequently to increasing the cross-sectional area thereof.

3. A method of operating a melting furnace comprising charging alternate layers of fuel and raw material into said furnace to form a column, with the fuel predominantly in the center but extending outwardly therefrom, and with the raw material predominantly around the walls but generally covering the fuel, and causing'the crosssectional area of the stratified charge to abruptly increase to loosen the same and inter-mix the fuel and raw material as the column moves through the furnace.

4. A method of operating a melting furnace comprising charging alternate layers of fuel and raw material into the furnace to form a column, with the fuel predominantly near the central axis of the combustion zone in the furnace but extending outwardly therefrom, and with the raw material predominantly around the walls but generally covering the fuel, abruptly increasing the cross-sectional area of the charge to loosen the same and intermix the fuel and raw material, and projecting air into the loose charge subsequently to increasing the cross-sectional area thereof.

5. A method of operating a melting furnace comprising creating a combustion zone near the bottom of the furnace, charging alternate layers of fuel and raw material into the furnace to form a column, with the fuel disposed predominantly above the center of the combustion zone but extending outwardly therefrom, and with the raw material predominantly around the wall but generally covering the fuel, abruptly increasing the cross-sectional area of the columnized charge just above the combustion zone, and projecting air into the loose charge subsequently to increasing the cross-sectional area thereof.

6. A method of operating a melting furnace comprising charging alternate layers of fuel and raw material into the furnace to form a column, with the fuel predominantly in the center and extending outwardly therefrom, and with the raw material predominantly around the walls but completely covering the fuel.

'7. A method of operating a melting furnace comprising charging alternate layers of fuel and raw material intothe. furnace to form a column, with the fuel predominantly in the center and extending outwardly therefrom, and with the raw material predominantly around the walls.

8. A method of operating a melting furnace in the manufacture of mineral wool fibres comprising forming in said furnace a column including alternate layers of fuel and mineral wool forming raw material, with the fuel predominantly above the center of the combustion zone in the furnace but extending outwardly therefrom in tapering configuration, and with the raw material predominantly around the walls but extending towards the main body of the fuel in tapering configuration, and abruptly increasing the cross sectional area of the column as it nears the combustion zone.

9. Acharged mineral wool melting furnace comprising a charging zone and a combustion zone, said charging zone containing alternate layers of fuel and raw material, with the fuel predominantly above the center of the combustion zone but extending to the furnace walls, and with the raw material predominantly around the walls of the. furnace but generally covering the fuel.

10.A charged mineral wool melting furnace comprising a charging zone and a combustion zone containing alternate layers of fuel and raw material, with the fuel predominantly in the center and extending outwardly therefrom, and

with the raw material predominantly around .the furnace walls but completely covering the. fuel.

11. A charged mineral wool melting furnace comprising a charging zone and a combustion zone, said charging zone containing alternate layers of fuel and raw material, with the fuel predominantly in the center and extending outwardly therefrom, and with the raw material predominantly around the walls.

12. A charged mineral wooLmelting furnace comprising a charging zone and a combustion zone of greater diameter than said charging zone,

said charging zone containing alternate layers of fuel and raw material, with the fuel predominantly in the center and extending outwardly therefrom, and with the raw material predominantly around the furnace walls.

13. A method of operating a melting furnace comprising charging alternate layers of fuel and raw material into the furnace to form a column, with the fuel predominantly in the center and extending outwardly therefrom, and with the raw material predominantly around the walls, permitting said charge to fall into a combustion zone, and projecting air into the charge in the combustion zone at adjusted locations inwardly of the walls thereof.

WILLIAM R. SEIGLE. HOWARD J. O'BRIEN. GEORGE S. SMITH.

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