US1953856A - Rotary internally fired kiln - Google Patents

Description

A. w. HEYMAN ROTARY INTERNALLY FIRED KILN Filed May 27. 1951 April 3, 1934.

2 Sheets-Sheet 1 April 3, 1934. A. w. HEYMAN ROTARY INTERNALLY FIRED KILN 1931 2 Sheets-Sheet 2 Filed May 27 Patented Apr. 3, 1934 UNITED STATES PATENT, OFFICE 6 Claims.

The present invention is concerned with improvements in rotary internally fired kilns, particularly with the provision of means for improving the lining of the kilns.

The 01 dinary method of lining kilns is to place a series of refractory bricks or blocks against the interior of the cylindrical steel shell so that the shell is completely covered with refractory material and protected from the direct heat of the flame in the interior of the kiln.

Kilns of this type have proven highly. satisfactory for many classes of work, but it has been found, however, that they are inherently defective when used for melting materials or for reducing them to a semi-molten state. The extreme heat necessary to actually melt the materials being treated acts to corrode and fuse the fire brick or other refractory material. The inner surfaces of the brick are gradually corroded and melted away until the lining becomes uniformly very thin, so thin in fact, that it will no longer sustain the arch which collapses and exposes the kiln shell to the direct heat of the flame.

The present invention aims to overcome this difficulty by so lining a kiln throughout at least that portion of its length which constitutes the fusion zone, that the uniform thinning of the lining and subsequent breaking down of the arch will be eliminated.

A preferred embodiment of the invention involves the use of lining material of the usual heat conductivity alternated with sections of carborundum or magnesite, but preferably with sections of aluminate cement. The kilns are ordinarily externally cooled either by air or by water and in consequence that portion of the inner surface of the kiln lining adjacent the cooling means employed will be maintained considerably cooler than the portion which is further removed. The

fire brick surfaces will still fuse and corrode to a certain extent but the slag which is melted off the fire brick surfaces will be built up on certain surfaces due to the fact that they are sufficiently cool to cause freezing of the slag and solidification of the material which is eaten away from the bricks.

The object of the present invention is to provide a kiln having cooling means which make it possible to completely fuse the raw materials which previously has been impractical on account of the severe attack on the kiln lining, causing it at times to burn through in only a few hours if the raw material was completely fused. The cooling elements break up the lining into small sections or arches and also make it possible to recoat and build up the lining to any desired thickness with fused material in the kiln.

Thus when the kiln is in operation the fusion zone thereof will present a corrugated or bumpy appearance having depressions at the points 30 where the fire bricks have been corroded and inwardly directed projections at the points where the material forming the lining is adjacent the cooling means. The general corrugated or uneven kiln' lining which is the result of melting slag in the kiln does not readily collapse or fail, even though the. bricks be appreciably melted down. In other words, the material Which-is fused from the brick and the slag from the materials being acted on in the kiln will for the most part be built up on those sections which are externally cooled and the inherent strength of the arch will not be materially decreased.

With these and various other objects in view, the invention may consist of certain novel features of construction and operation, as will be more fully described and particularly pointed out in the specification, drawings and claims appended hereto.

In the drawings, which illustrate an embodiment of the device and wherein like reference characters are used to designate like parts- Figure l is a longitudinal sectional view through the fusion zone of a kiln equipped with the improved lining and provided with the structural features of the present invention;

Figure 2 is a transverse sectional view taken on line 2--2 of Figure 1;

Figure 3 is a transverse sectional view taken on line 33 of Figure 1;

Figure 4 is an enlarged sectional detail view of the cooling element, as secured to the shell of the kiln;

Figure 5 is a fragmentary transverse sectional view through a modified type of kiln;

Figure 6 is a longitudinal sectional view of the same; I

Figure 7 is a fragmentary transverse sectional view through another modified form of kiln; and

Figure 8 is a longitudinal sectional view of the same.

In Figures 1, 2 and 3 of the drawings there is illustrated one form of kiln embodying the present invention which includes a cylindrical steel shell 10 having secured thereto, preferably centrally, operating means for causing rotation of the kiln including annular strips 11 and an annular ring 12 mounted thereon to which is secured a circular gear 13. The gear is adapted to have meshing engagement with any suitable positively driven gear for rotating the kiln at desired speed. At other points in the length of the kiln there are secured in a similar manner an annular ring 14 which forms a track for engaging a plurality of rotatably mounted rollers by means of which the kiln is mounted for rotary movement.

An important feature of the invention is the provision of cooling means, Figure 4, which include U-shaped elements or trough-like members 15, welded or otherwise suitably secured to the inner surface of the kiln shell and positioned with respect to openings 16 provided in the shell so that one inner wall of the element is in alignment with one side of the openings. Secured to the exterior of the shell are a plurality of bailie plates 17 which are positioned so as to extend over the opening 16 in the shell for purposes which will be presently described. The cooling elements 15 are provided with end walls 18 and certain of the elements are provided with dividing walls 20 which divide the element into two equal compartments and each compartment having associated therewith one or two of the openings 16.

The length of the cooling elements 15 vary, as clearly shown in Figure 1, the sections, however, extending the complete circumference of the shell.

It has also been found desirable to stagger the cooling elements at one section with those of another section so that the interior surface of the kiln is broken up into a number of smaller sections or arches.

The lining for the kiln comprises fire brick 21 of the general shape as shown in Figures 2 and 3 and which are positioned with their greatest height adjacent the cooling elements 15 and with the reduced end of one fire brick adjacent the reduced end of the adjacent fire brick. The fire bricks 21 are of a relatively narrow width and are positioned in a direction at right angles to the length of the cooling elements 15. The space directly over the cooling elements is filled with aluminate cement 22, as is also the space between the reduced end of the fire brick. In addition to the cement any plastic refractory material may be used to form a binding agent for holding the fire bricks 21 in position between the cooling elements.

In the operation of the kilns a cooling medium, such as water, is adapted to be sprayed on the outside of the shell 10, and as the kiln rotates, quantities of the water will be collected by the battle 1'? and directed into the U-shaped members 15 through openings 16 forming cooling means. Upon the kiln rotating a half revolution from the point where the cooling fluid entered the elements, the same will be in a position to discharge a portion of the fiuid, but, by reason of the positioning of the opening 16, all of the cooling fluid will not be discharged until the kiln has rotated another quarter of a revolution. The extreme heat necessary to actually fuse the materials being treated, acts to corrode and fuse fire brick or other refractory material used, which is eaten away from a point indicated by dotted lines 23, Figure 2. Due to the fact that the cooling elements 15 are employed, the slag which necessarily must form on the inner surface of the lining is solidified or freezes and it has been found that this coating of slag will build up on the, lining to a point indicatcd by line 24, Figure 3. In this manner the refractory lining of the kiln has protection and the uniform corroding of the lining and subsequent break-down of the arch is eliminated. Also, by reason of the cooling elements the lining is broken up into'a number of small sections, each section being confined between a pair of cooling elements which thus form supporting means for the same.

In Figures 5 and 6 there is illustrated a modification in which ordinary fire brick 25 is alternated with longitudinally extending rails or strips 26 of metal or other highly conductive material. In this form of kiln the same action described above takes place, the fire brick being corroded and the slag solidifying on the rails 26 to produce a generally corrugated lining structure.

In Figures 7 and 8 there is illustrated a modification in which a series of spines 28 project radially inwardly from the shell 10, the spines 28 being in the nature of capped metal pipe sections. The interspaces between the spines are preferably filled either with the molten material being treated or with a lining of plastic refractory material 30. The metal pipes 28 open on the exterior surface of the shell 10 and thus function as cooling means since the water sprayed upon the shell will be alternately collected and discharged from the tubular pipes. The same result is accomplished as above, the material building up on the inner ends or"- the spines and being corroded intermediate the same, so that an arch of substantial strength is produced.

It is to be understood that I do not wish to be limited by the exact embodiment of the device shown, which is merely by way of illustration and not limitation, as various and other forms of the device will of course be apparent to those skilled in the art without departing from the spirit of the invention or the scope of the claims.

I claim:

1. A rotary internally fired kiln including a shell, a plurality of cooling means secured to the interior surface of the kiln and arranged in staggered relationship, refractory bricks positioned on the interior surface of the kiln in the spaces formed by the cooling means, whereby portions of the brick adjacent the cooling means are cooled.

2. A rotary internally fired kiln including a shell, a plurality of cooling elements secured to.

the interior surface of the kiln, openings in the kiln shell in alignment with the elements, said elements being hollow and adapted to be supplied with a cooling fluid through the openings, and refractory bricks lining the shell in those spaces formed by the elements.

3. A rotary internally fired kiln including a shell, a plurality of cooling elements secured to the interior surface of the kiln, openings in the kiln shell in alignment with the elements, said elements being hollow and adapted to be supplied with a cooling fluid through the openings, said cooling elements being arranged in staggered relationship, and refractory bricks lining the shell in those spaces formed by the elements.

4. A rotary internally fired kiln including a shell, a plurality of cooling elements secured to the interior surface of the kiln, openings in the kiln shell in alignment with the elements, said elements being hollow and adapted to be supplied with a cooling fluid through the openings, bafiie plates secured to the exterior of the shell for directing the cooling fluid into the openings, and a refractory lining for the interior surface of the shell, said lining being coated by the material being treated.

5. A rotary internally fired kiln including a shell, a plurality of cooling elements secured to the interior surface of the kiln, openings in the kiln shell in alignment with the elements, said elements being hollow and adapted to be supplied with a cooling fluid through the openings, and a refractory lining for the interior surface of the shell, the lining covering the elements being of a dissimilar material from the remainder of the lining.

6. A rotary internally fired kiln including shell, a plurality of cooling elements secured to the interior surface of the kiln, openings in the

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