US3502311A - Coolers for rotary kilns - Google Patents

Description

March 24, 1970 F. E. JENSEN 3,502,311

COOLERS FOR ROTARY KILNS Filed May 15, 1968 2 Sheets-Sheet 1 FIG. 1

INVENTOR FLEMMING EDVIN JENSEN ATTORNEYS United States Patent 3,502,311 COOLERS FOR ROTARY KILNS Flemming Edvin Jensen, Copenhagen-Valby, Denmark, assignor to F. L. Smidth & C0., New York, N.Y., a corporation of Delaware Filed May 15, 1968, Ser. No. 729,275 Claims priority, application Great Britain, May 17, 1967, 22,877/67 Int. Cl. F02m 37/ 00 US. Cl. 263-32 6 Claims ABSTRACT OF THE DISCLOSURE An improvement in rotary kilns of the type having a number of cylindrical cooler tubes mounted around the outlet end of the kiln with their axes generally parallel to the axis of the kiln. The inlet end of each tube is connected to an outlet of the rotary kiln by a supply chute through which material to be cooled enters the cooler tube. The improvement is in the inlet end of each supply chute which is formed by a sleeve having a heatresistant lining. The sleeve is inserted from the outside of the kiln into an outlet in the wall of the kiln and extends through the kiln shell to the interior surface of the kiln lining. This construction reduces wear on the supply chutes and permits ease of replacement of any Worn parts.

BACKGROUND OF THE INVENTION This invention relates to coolers for material burnt or sintered in a rotary kiln, specifically to that type of cooler with comprises a number of cooler tubes mounted around the outlet end of the kiln with their axes parallel or substantially parallel to the axis of the kiln. Each cooler tube has an inlet at one end of the tube and an outlet at the other end, the inlet end of each tube being connected to an outlet of the rotary kiln by a supply chute through which material to be cooled enters the cooler tube. Cooling air drawn or blown through each cooler tube passes as preheated secondary combustion air through the same chute to the interior of the kiln.

The cooler tubes are commonly arranged symmetrically around the kiln and may be parallel or inclined at. a slight angle to the axis of the kiln. To further the heat exchange in the cooler tubes and to assist in passing the material from the inlet of the cooler tube to its outlet, special devices, such as lifters, scoops, or chains, are often provided inside the cooler tubes. The cooler tubes may extend from their inlets either upwards towards the inlet end of the kiln or downwards away from the inlet end of the kiln.

During rotation of the kiln the material being burned or sintered lies mostly to one side of the central diametral plane, advancing in a rolling and sliding motion down through the kiln. The material passes out of the kiln through the outlet holes as the kiln rotates, and as each outlet hole comes to the bottom of the kiln. Due to the rotation of the kiln the material will not fall straight through the outlet holes but fill hit the wall of the supply chutes linking the kiln to the cooler tubes. Cement clinker, and similar materials processed in the kiln are very hard and tend to wear away the supply chutes and the cooler tubes. Furthermore as the material processed in the kiln is very hot when it leaves the kiln, the supply chutes to the cooler tubes are heated by the material to a high temperature, and this reduces their resistance to abrasion, thus increasing the rate of wear. For this reason the supply chutes have to be frequently replaced, and thus involves considerable loss of production during the shut-down of the kiln necessary for maintenance.

To reduce or prevent this wear it has previous y been 3,502,311 Patented Mar. 24, 1970 proposed to provide chutes having an inclination to the kiln shell corresponding to the direction of the stream of material falling through the outlet holes so that the material falls freely through the chutes without hitting the Walls. Although some reduction in wear can be achieved in this way, the reduction is only obtained when small amounts of material are being processed. When production is increased and larger kilns are used, it is ditficult to maintain and control a constant stream of material through the outlets and the material will then fall through the holes in random directions. In any case, inclined chutes are rather complicated to make and mount on the kiln.

It is the object of the present invention to provide a rotary kiln with a cooler in which the wear on the supply chutes is reduced to a minimum, and in which the construction of the chutes is such that it is possible to replace any worn parts simply and quickly.

SUMMARY OF THE INVENTION According to the invention, the inlet end of each supply chute is formed by a sleeve having a heat-resistant lining, the sleeve being inserted from the outside of the kiln into an outlet in the wall of the kiln and extending through the kiln shell to the interior surface of the kiln lining. The inlet sleeve may then be connected directly to the cooler tube, or there may be an intermediate sleeve also with a heat-resistant lining between the inlet sleeve, and the cooler tube. In such constructions, the inlet sleeve or the intermediate sleeve or both can easily be rep aced from the outside of the kiln.

The preferred form of heat resistant lining is one made of ceramic, since this is more resistant to wear at high temperatures than is a conventional brick refractory lining and can also be pro-formed and installed as a whole. Preferably the lining or linings are in the form of a monolithic tube of ceramic, and such linings are not only simple to replace, but also strengthen the sleeves they are lining; alternatively the linings may be made up from several parts, for example formed from ringlike sections packed one on top of another in the sleeves. Refractory linings, particularly those of ceramic, are brittle, especially at edges and corners, and the ends of the linings of the sleeves should thus preferably be protected by means of annular steel rings mounted in the sleeves at either end of the lining; such rings serve also to strengthen the sleeves and to locate and retain the linings in the sleeves.

The inlet sleeve should preferably be formed with one or more axial slits in its surface at the end which extends into the kiln; this will allow for expansion of the lining at the hot end of the inlet chute nearest the interior of the kiln.

Advantageously the inlet sleeve is conical, its diameter decreasing towards the interior of the kiln. In this way there is less danger of the sleeve becoming jammed in the kiln wall by processed material packing around it. Clearly one part of the lining will receive the most wear, and it is thus desirable that the inlet sleeve be mounted on the kiln in such a way that it can be rotated about its axis to a fresh position, this exposing unworn lining to the abrasion of the material falling from the kiln. In this Way the overall life of the lining can be prolonged. If the sleeve is conical, then such rotation is facilitated.

The cooler tubes are normally rigidly mounted on the kiln, and provision for heat expansion must therefore be made in the supply chutes. A suitable expansion joint must be made between the kiln and each cooler tube, or between the kiln and each intermediate sleeve, to allow for expansion of the chute in length as well as in diameter, designed in such away that no material may escape through it. This may be done by incorporating suitable heat resistant packings in the joint. Preferably the joint is provided between the kiln and the intermediate sleeve, where material does not accumulate; this is found to be more eflicient than forming the joint at the inlet end of the cooler tube itself.

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a view partly in side elevation and partly in central section of the discharge end of a combined rotary kiln and cooler combination.

FIG. 2 is a longitudinal section through part of a rotary kiln, showing an outlet of the kiln, the inlet end of a cooler tube and the chute connecting the outlet with the inlet end of the cooler tube, and

FIG. 3 is an enlargement of part of FIG. 2, showing in detail a longitudinal section through the mounting of the inlet sleeve, the connection between the sleeve and the kiln, and the expansion joint.

DESCRIPTION OF THE PREFERRED EMBODIMENT The discharge end of a combined rotary kiln and cooler apparatus is shown wherein a rotary kiln 11 comprises a shell 12 and a refractory brick lining 13. One outlet from the kiln is shown through a flanged pipe stud 14. The outlet through the pipe stud 14 leads to a cooler tube 15 through a supply chute 16, comprising an inlet sleeve 17 having a monolithic ceramic lining 18 and an intermediate sleeve 19 having a monolithic ceramic lining 20. The cooler tube 15 is provided with a refractory brick lining 21.

The ceramic lining 18 is held in position in the inlet sleeve 17 by means of annular steel rings 22 in the ends of the sleeve, these rings protecting the ends of the ceramic lining from impact on them of the material in the kiln. The sleeve 17 has a flange 23 (FIG. 3) and is held in position in the pipe stud 14 by a ring 24 bolted to the stud; it is also formed with longitudinal slits 26 to allow for expansion of the lining nearest the interior of the kiln. An expansion joint is provided by means of a sealing ring with grooves 27 and 28, in which heat resistant packing material 29 is embedded, thus allowing for longitudinal or diametric expansion of the intermediate sleeve.

When the pipe stud 14 is approximately in the position shown in the drawing, that is at its lowermost position, material processed in the kiln 11 will pass through it and the supply chute 16 to the interior of the cooler tube 15. As the kiln rotates the cooler tube rotates together with it, and the material is conveyed by gravity through the cooler tube from the inlet end to the out let end, the discharge end of the kiln shown in FIG. 1 being at a lower elevation than the opposite or infeed end for the raw material. Cooling air is drawn or blown through the cooler tube and passes into the kiln through the supply chute in countercurrent to the stream of material.

The material passing into the chute hits the walls of the chute, generally in one specific area, but the ceramic linings 18 and 20 resist the abrasive effect of the hot material.

As the inlet sleeve 17 recessed in the pipe stud 14 is tapered towards the interior of the kiln, it is easily detachable, even when the space between the sleeve and the brick lining 13 or between the sleeve and the pipe stud 14 is filled with dust. Consequently, the sleeve 17 may be loosened and turned about its own axis so that the wear on the lining 18 may be distributed over the whole of the circumference. The whole sleeve 17 with lining 18 may also be replaced completely in one operation. Such of the two rings 22 as are flush with the kiln lining 13 may be equipped with a transverse rib (not shown) serving to prevent clinker lumps too big from passing into the supply chute 16.

I claim:

1. In a rotary kiln of the type having a number of cylindrical cooler tubes mounted around the outlet end of the kiln with their axes parallel or substantially parallel to the axis of the kiln and the inlet end of each cooler tube connected to an outlet of the rotary kiln by a supply chute, the improvement in combination therewith comprising an inlet end of each supply chute formed by a flanged sleeve having a heat-resistant lining, the sleeve being inserted from the outside of the kiln into an outlet in the wall of the kiln and extending through the kiln shell to the interior surface of the kiln lining, the inlet sleeve being conical and the lining thereof being in the form of a monolithic conical tube of ceramic.

2. In a rotary kiln of the type having a number of cylindrical cooler tubes mounted around the outlet end of the kiln with their axes parallel or substantially parallel to the axis of the kiln and the inlet end of each cooler tube connected to an outlet of the rotary kiln by a supply chute, said supply chute comprising an inlet sleeve and an intermediate sleeve, each of said sleeves being of steel, the inlet sleeve being inserted from the outside of the kiln into an outlet in the wall of the kiln and extending through the kiln shell to the interior surface of the kiln lining, the lining for said supply chute being formed of several ring-like sections of ceramic packed one on top of another in the two sleeves.

3. A kiln according to claim 2 in which an expansion joint is provided between the kiln and the intermediate sleeve.

4. In a rotary kiln of the type having a number of cylindrical cooler tubes mounted around the outlet end of the kiln with their axes parallel or substantially parallel to the axis of the kiln and the inlet end of each cooler tube connected to an outlet of the rotary kiln by a supply chute, the improvement in combination therewith comprising an inlet end of each supply chute formed by a flanged sleeve having a heat-resistant lining, the sleeve being inserted from the outside of the kiln into an outlet in the wall of the kiln and extending through the kiln shell to the interior surface of the kiln lining, the sleeve lining being protected and located and retained in the sleeve by annular steel rings.

5. In a rotary kiln of the type having a number of cylindrical cooler tubes mounted around the outlet end of the kiln with their axes parallel or substantially parallel to the axis of the kiln and the inlet end of each cooler tube connected to an outlet of the rotary kiln by a supply chute, the improvement in combination therewith comprising an inlet end of each supply chute formed by a flanged sleeve having a heat-resistant lining, the sleeve being inserted from the outside of the kiln into an outlet in the wall of the kiln and extending through the kiln shell to the interior surface of the kiln lining, the sleeve being formed with one or more axial slits in its surface at the end which extends into the kiln.

6. In a rotary kiln of the type having a number of cylindrical cooler tubes mounted around the outlet end of the kiln with their axes parallel or substantially parallel to the axis of the kiln and the inlet end of each cooler tube connected to an outlet of the rotary kiln by a supply chute, the improvement in combination therewith comprising an inlet end of each supply chute formed by a flanged sleeve having a heat-resistant lining, the sleeve being inserted from the outside of the kiln into an outlet in the wall of the kiln and extending through the kiln shell to the interior surface of the kiln lining, the inlet sleeve being conical and so mounted in the kiln that it can be rotated about its axis to a fresh position.

References Cited UNITED STATES PATENTS 1,652,168 12/1927 Fasting 26332 1,653,050 12/1927 Lindhard 263-32 2,845,259 7/1958 Henrichsen 263-32 JOHN J. CAMBY, Primary Examiner

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