US2450013A - Apparatus for producing rock wool - Google Patents

Description

o. J. NELsoN `APPARATUS FOR PRODUCING ROCK 00D sept', 2s, 194s.

2 Sneaks-Shea Filed May 5, 1943 vFiled lay 5. 1943 sept. 2s, 194s. Q. J. NELSON 2,450,013

APPARATUS Fon Pnonucmeock woop 2 sheets-#sheath Patented Sept. 28, 1948 2,450,013 APPARATUS FOBPRODUCING ROCK WOOL Oliven' J; Nelson, Parsons, Kans., assigner to himself as trustee f Application May s. 1943. serial No. sans (ci. zes-21) l 15 Claims,

This invention relates to apparatus for producing molten slag for use in rock or mineral wool. It does not, however, contemplate the use of novel means for blowing the slag, its novelty being confined to means for melting and heat conditioning the material preparatory to blowing. l

The general object of the inventionV is to provide means for eillc'iently producing in a facile manner molten slag in a uniform condition suit' able for blowing.

A specific object of the invention is to provide apparatus employing a cupola and a method whereby such a slag may be producedv bygas firing. Heretofore a cupola has been used for the production of slag but only when a solid fuel, coke', was used, the fuel being mixed with the rock before or asv the cupola was charged. The -use of a gaseous or liquid'fuel has been proposed but no instance is known where success has attended any lprior attempts to use this type of fuel. The presence in some localities of large supplies of natural gas makes such ya. procedure desirable. P

While the novelty of theinvention is defined in the appended claims, it may be stated broadly that success ofthe apparatus has been obtained primarily by an arrangement in which an upper wall or arch is spaced above a lower wall or Weir leaving a space for the continuous flow of molten material over the Weir, with a flame directed into the cupola approximately from this space; all arranged in such a manner that the slag bleeds off without blocking the opening.-

The results have been obtained by the use of surface combustion. A combustible mixture of fuel and air are expelled from-the burners positioned at or proximate the exit, so that'they are projected upon the surrounding rock which forms a mantle therefor.

The exit from the cupola leads to a forehearth in which further heat is applied and where that heat can be closely regulated to pro` duce a slag of the exact consistency required.

Other novel arrangements are present, such as the introduction of the combustible mixture through the upper wall, or arch, which is water cooled, so that the fuel may be mixed with air before introduction to the burners.

Fig. 1 is a top plan view of a cupola or a furnace embodying this invention;

Fig. 2 is a front elevational view;

Fig. 3 is a side elevational view;

Fig. 4 is a section on line 4.4, Fig. 3;

Fig. 5 is a section on line 5 5, Fig. 2; and

Fig. 6 is a section on line 6 8, Fig. 3.

The furnace includes a cupola and a forewall 2, constructed of spaced metal'plates form' ing a water Jacket. These walls extend upwardly from the base of the furnace a distance, in a typical installation, of eightfeet. Above these walls there is a hood 3, constructed preferably of sheet metal and leadingto a stack 4. Charging doors! are positioned in the front of the hood I.

The front wall of the cupola is water cooled and has a top vertical section 6. but with the inner plate of this vertical section connected to an inclined plate 'I forming yan inclined wall above the outlet of the cupola. The lower end of this front wall forms an arch 8 which is spaced above a bottom water cooled wall or weir 9, thus forming a slot or opening I0 which communicates with the forehearth. The bottom of the cupola has a dump door Il.

The forehearth has masonry side walls I2, masonry arch or roof I3, and front wall I4. The

. weir 9 rests against a masonry wall I5 in the hearth. The furnace has side walls I and a rear forehearth. The Walls of the forehearth are surrounded by a water jacket. Slag notches I6 are positioned in the front of the forehearth, through which the molten slag is discharged for blowing. The bottom of the forehearth is provided with dump doors I1.

'I'he dump doorsl II andI1 are covered with a illl composed preferably of six inches of mineral wool I9 placed directly on top of the doors, and three inches of earth I9 on top of the mineral wool. This earth may be clay or soil existing at the plant location.

The Weir 9 is inclined forwardly from top to bottom at an angle of approximately while the` slope of the upper wall 'I is approximately 45. The burners 30 are directed downwardly and inwardly in such a way, and in such proximity, that the opening I0 is in a very hot zone. The water jacket of the walls is connected with the weir 9 as well as with the inclined upper front wall so that the entire system is interconnected and may be served by a water inlet 20 and an outlet 2I.` The heated water, or as much as is needed, may be used for boiler water to produce steam for blowing, and the remaining portion may be cooled by means of a spray pond. A pump for circulating the water and the spray pond are not shown, such means being well understood in the art.

in the jacket, thus protecting it from pre-ignif4 tion,

rality ofburners 23 projecting downwardly from the top wall or arch I3 of the forehearth, and are supplied from a manifold 24. Where it is desirable to eliminate some undesirable compounds. especially sulphur compounds, from the rock, an oxidizing flame may be employed by introducing an excess of air in the fuel mixture.

vIn the forehearth the bottom of the slag notches I6 is slightly above the bottom of the iorehearth, formed by the earthen layer I9, so that a body of molten slag is kept in the forehearth. This gives a better opportunity for controlling the viscosity of the slag at the outlet. An additional result is obtained by this arrangement, where the cupola is charged with more than one kind of material. Sometimes it ls necessary to use a mixture of two or more kindsv of materialwto make a satisfactory wool, or a particular type of wool. In such a case if a pool of molten material is maintained in the forehearth. the different materials have a time perlod for soaking and combining together before flowing through the outlet to the blowing nozzle.

The ffurnace may be supported in any convenient manner. Preferably it lls positioned on I-bea-ms beneath the walls, the I-beams being supported by pillars sufficiently above the floor to give satisfactory working conditions under the furnace for cleaning it out.

The following is, by way of illustration, a chemical analysis of a typical rock which has been used andfound satisfactory in the operation of Y the apparatus:

Calcium oxide 26.00 Iron alumina oxide 1.21 Silicon dioxide 45.55 Magnesium dioxide .4'7 Sulphur trioxide .41 arbon dioxide 20.36

The rock charged to the cupola is of a size from one to four inches, with a normal amount of fine material left from crushing and screening. The rock is charged to the cupola through the doors 5 in such a way that the sides are kept considerably higher than the center. This tends to con.- flne the heat to the center of the cupola, causing a minimu-m heat loss in the water jacket, and a maximum melting effect in the center. This center melts rapidly and caves down as the molten slag runs into the forehearth. As the center caves the hot calcined rock, which is high on the sides, slides into the caved center and additional rock is then charged to the sides to keep -feet from the burners, under the typical conditions here described, including la gas pressure of one point'per square inch at the nozzles.

It is found that the melting zone exists in an area about as indicated on Fig. 5. and extending rearwardly from the burners about twenty-four inches. and downwardly and upwardly from a vvertical line passing through the burner a maximum of twelve to fifteen inches. 'About this melting zone there exists a. preheating and calcining zone extendingupward'ly from the top of that zone about two feet, and above that zone the moisture is removed by evaporation.

It has been observed on dfumplngthat little change has taken place in the rock below the combustion or melting zone-,land slag does not tend to settle to the bottom of the cupola.

In starting up, the forehearth burners 23 are lighted and fuel f low gradually increased until slagging begins before the back burners are turned on. The cupola is first charged with rock to a height of about one foot above the back burners. As the rock shows color on the surface. additional rock is charged from time to time until the charge is about six inches from the top of the water walls. In charging the cupola the fresh charge is placed next to the shell and the rock is kept twelve inches or more higher at the shell than in the center. 'I'he center core caves down and fresh rock is periodically charged to the outside as described above.

After slagging begins, the back burners are turned on and fuel pressure gradually increased to maximum fire. Between three and four hours are required to start blowing from the time the hearth burners are lighted. The operation is, of course, lcontinuous thereafter until it is de sired to close down the furnace for servicing or for other reasons.

When shutting down the furnace the charging is stopped and the rock is melted down until the re from the back burners breaks through.r The back burners are then shut off. but the forehearth burners are left on until slaglging diminishes to a point unsuitable for blowing. If desired, the back and furnace burners can be shut olf with the cupola full of rock, |and the cupola dumped immediately, as there is very little slag in the cupola. The cupola dumps fairly clean, but there will be some scabs of slag along the inclined upper wall or arch, and along the upper part of the Weir.

The problem presented, and which has been solved by this invention, is 'to secure a flow of slag into the forehearth without the slag carrying with it any unmelted rock, and without the rock caving or the slag flowing out of control, to cut off the slag outlet into the forehearth. This is assisted by the inclination of the walls above and below the outlet I0. It has been found that a substantial variation in the size of the opening i0, or in the lateral positioning of the weir 0 with respect to the arch l, will ruin the results. A vertical distance of six inches, between the top of the weir 9 and the bottom of the arch 8, is correct for the size of rock and pressure of the fuel. A variation of these conditions might require a change in the size of opening. It is believed, however, that this distance is correct for ordinary operating conditions. Experience indicates that the top of the weir should be almost directly below the bottom of the arch 8. The inner surface of the lip of the Weir. as well as the slot or opening I0, must be in the region of intense heat.

Melting takes place seemingly only in the combustion zone, so that this melting is the result of surface combustion on the rock, and not to any great extent as a result of radiation and convection, although asindicated, the heat from the forehearth is suicient to start the slagging. It

- invention accomplishes -its is probable that heat from the forehearth assists materi ly in applying heat directly at the outlet in this way maintaining proper operat-K inl conditions at the outlet.

area to give a relatively high yield of slag.

The fact that the slag does not tend to vsettle to the bottom of the cupola, indicates that an unusual occurrence takes place. The viscous slag flowing over the weir tends to drag with it the molten material back out of the outlet and from below the top of the weir. The back burners apply an intense heat at these critical locations so that any rock entrainedwith -the slag is completely melted before it passes over the weir. The drag or pull of the slag passing over the weir and falling to the bottom of the forehearth is sumcient to elevate the molten slag back of the weir to such an extent as to prevent its passing to the bottom of the cupola.

The'slope of the walls above and below the opening Ill and their relative arrangement. with the arrangement of the back burner, is such as to prevent a collapse of the material in the cupola to the extent that it will block the exit, or to an extent that unmeited rock will ilow over the weir with the melted slag.

As the molten slag flows over the weir l and cascades to the bottom of the forehearth, its viscous character serves to drag with it slag from the bottom of the melting zone although that may be considerably below the top -oi? the weir. v'Ivhis dragging effect serves to bleed the molten material from the mixture of rock and slag throughout the fusion zone. While the compactness of ilcations of the burners, liquid or even pulverized fuel may be employed.

It will be seen from the foregoing that the objects. Various changes may be made in the details of construction, within the scope of the appended claims, without departing from the spirit of this invention. Parts of the invention may be used to advantage without the whole. and improvements may be added while retaining the benets of the invention. l

I claim:

1. A cupola for fusing material having an opening for the discharge of fused material, said opening being formed by an upper wallor arch spaced above a bottom wall or weir, the arch being hollow to hold water. and a burner in the cupola projecting. inwardlyl from the arch and connected through a shell of the arch to a manifold within the hollow of the arch and therein surrounded by water.

. 6 wardly from the opening. and a burner in the cupola at the opening. so positioned and directed that the area across, above and directly to the rear of the opening is a melting zone subject to heat sumciently high to readily fuse the material.

3. A cupola for fusing material having an opening for the discharge of fused material, said opening being formed by an upper wall or arch spaced above ya bottom wall or weir, the interior side of the upper wall being inclined upwardly and outwardly from the opening, the interior side of the lower wall being inclined inwardly and downwardly from the opening, and a burner in the cupola at the opening, so positioned and directed that the area across, above, below. and directly to the rear of the opening is a melting zoneosubjected -to heat sufficiently high to readily fuse the material.

4. Apparatus for fusing material comprising a cupola having an opening for the discharge of fused material, said opening being formed by an upper wall or arch spaced above'a bottom wall or weir, the interior side of the upper wall being inclined upwardly and outwardly from the opening, the interior side of the lower wall being inclned inwardly and downwardly from the openv ing, a burner in the cupola at the opening, so

positioned and directed that the area across. above, below, and directly to the rear of the opening is a melting zone subjected to heat sufflciently high to readily fuse the material, and a forehearth communicating with the cupola through said opening having independent burncrs, whereby the heat therein may be regulated to produce a desired consistency of the material before discharge therefrom.

5. A cupola for fusing material having an openlng for the discharge of fused material, said opening being formed by an upper wall or arch spaced above a bottom wall or weir, the interior side of the upper wall being inclined upwardly andI outwardly from the opening, the interior side` of the lower wall being inclined inwardly and downwardly from the opening, and a burner in the cupola at the opening, so positioned and directed that the area across, above, below, and directly to the rear of the opening is a melting zone subjected to heat suillciently high to readily fuse thematerial, the opening being of a height above a floor outside the cupola sufliciently great- I er than the depth of the melting zone belowthe opening that the flow of viscous molten material in passing through the opening and falling-to said floor will drag the molten material from the bottom of the melting zone.

6. In the method of fusing solid material, pro viding a body ofy raw material in a chamber. projecting a combustible mixture of air and fuel into a section of the chamber and burning they fuel upon the surface and in the interstices of the said material by surface combustion in a manner and extent to fuse progressively the material in said section, withdrawing fused material from said section and from the chamber as it is formed. thereby permitting said section to be fed with raw material by gravity, and conducting the combustion gases outwardly and up wardly from said section whereby the raw material about and above the section is preheated by convection and conduction.

7. In the method of fusing solid material. providing a body of raw material in a chamber, projectlng a combustible mixture o f air and fuel into a section of the chamber and burning the fuelupon the surface and in the interstices of the 7 said material by surface combustion in a manner and extent to fuse progressively the material in said section, withdrawing fused material from said section and from the chamber as itis formed, thereby permitting said section to be fed with raw material by gravity. conducting the combustion gases outwardly and upwardly from said section whereby the raw material about and above the section is preheated by convection and conduction, and then further conditioning the fused material Ato bring it to a desired temperature and consistency by subjecting it to applied heat in a second chamber.

8. In the method of fusing solid material, providing a body of raw materialin-a chamber, pro jecting a combustible mixture into a section of the chamber laterally to the rear of a restricted opening-in the chamber to cause surface combustion on the material insaid section in a manner and extent to fuse progressively the material in said section, bleeding fused material from said section through said opening as it is formed.

thereby permitting saidsection to be fed with' raw material by gravity, and conducting the com-v bustion gases outwardly and upwardly from said section whereby the raw material about and above the section is preheated by convection and conduction. y

9. In the method of fusing solid material, providing a body of raw material in a chamber, projecting a combustible mixture into a section of the chamber laterally to the rear of a restricted opening in the chamber to cause surface combustion on the material in said section in a manner and extent to fuse progressively the material in said section, bleeding fused material from said section through said opening as it is formed, thereby permitting said section to be fed with raw material by gravity, conducting the combustion gases outwardly and upwardly from said section whereby the raw material about and above the section is preheated by convection and conduction, and then further conditioning the fused material to bring it to a desired temperature and consistency by subjecting it to applied heat in a forehearth adjacent the fusion chamber.

10. Apparatus for fusing solid material comprising a fusion chamber adapted to be filled with raw material, a forehearth at one side of and communicating with the fusion chamber through an opening in a wall separating the fusion chamber from the forehearth, a fuel nozzle in the fusion chamber at and inwardly directed from the said opening whereby a mixture of fuel and air flowing under pressure through the nozzle will burn by surface combustion upon the surface and in the interstices of the material in the fusion chamber directly to the rear of the opening. and a separate burner in the forehearth.

11. Apparatus for fusing solid material comprising a fusion chamber adapted to be filled with raw material, a forehearth communicating with the fusion chamber through an opening in a wall separating the fusion chamber from the forehearth, a burner for heating the forehearth, a fuel nozzle in the fusion chamber at and inwardly directed from the said opening whereby a mixture of fuel and air flowing under pressure through the nozzle will burn by surface combusltion upon the surface and in the interstices of the material in a melting zone in the fusion chamber directly to the Arear of the opening, the

opening being approximately six inches in height and substantially above the bottom of the forehearth whereby flow of viscous molten material in flowing through the opening and falling to the noor of the forehearth will drag molten material from the melting zone in the fusion chamber'.

12. Apparatus for fusing solid material` comprising a fusion chamber adapted to b e filled with raw material. a heated forehearth communicating with the fusion chamber through an ,opening ln a wall separating the fusion chamber from the forehearth, and a fuel nozzle in the fusion chamber at and inwardly directed from the said opening whereby a mixture of fuel and air flowing under pressure through the nomic will burn by surface combustion upon the surface and in the interstices of the material in a melting zone in the fusion chamber directly to the rear of the opening, the opening being of a height above the forehearth sufilciently greater than the depth of the melting zone below the opening that the flow of viscous molten material in passing through the opening and falling to the bottom of the forehearth will drag the molten material form the bottom of the melting zone.

13. A cupola for fusing solid material having an opening for'the discharge of fused material, said opening being formed by an upper wall or arch spaced above a bottom wall or weir, and a fuel nozzle in the cupola at and inwardly directed from the said opening whereby a mixture of fuel and air flowing under pressure through the nozzle will burn by surface combustion upon the surface and in the interstices of the material in the cupola directly to the rear of the opening.

14. A cupolafor fusing material having an open'ing for the discharge of the fused material, saidL opening being formed by an upper wall or arch spaced above a bottom wall or weir, the interior side of the upper wall being inclined upwardly and outwardly from the opening, and a plurality of nozzles in the cupola at the opening for the introduction of a gaseous component of combustion, so positioned and directed that fuel in the area across, above and directly to the.

rear of the opening will burn in said zone at a heat sufficiently high to readily fuse the material.

15. A cupola for lfusing material having an opening for the discharge of the fused material, said opening being formed by an upper wall or arch spaced above a bottom wall or Weir, the interior side of the upper wall being inclined upwardly and outwardly from the opening, a gas line for carrying oxygen, and a plurality of nozzles connected with the gas line in the cupola at the opening for the introduction of a gaseous component of combustion, so positioned and directed that fuel in the area across, above and directly to the rear of the opening will burn in said zone at a heat sufficiently high to readily fuse the material.

OLIVER. J. NELSON.

REFERENCES CITED y The following 'references are of record in the file of this patent:

UNITED STATES PATENTS Number Name Date 1,032,745 Dow July 16, 1912 1,322,516 Barnes Nov. 25, 1919 1,656,828 Powell Jan. 17, 1928 2,057,393 Powell Oct. 12, 1936 2,165,242 Drill Julyll, 1939 2,311,870 Richardson Feb. 23, 1943 y

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