GB2150271A

GB2150271A - Rotary kiln and cooler lifters

Info

Publication number: GB2150271A
Application number: GB08428270A
Authority: GB
Inventors: Kenneth Ellis
Original assignee: Williamson Cliff Ltd
Current assignee: Williamson Cliff Ltd
Priority date: 1983-11-24
Filing date: 1984-11-08
Publication date: 1985-06-26
Also published as: IE843000L; DE3442698A1; GB8331386D0; GB8428270D0; IE55928B1; GB2150271B

Abstract

A lifter assembly for a rotary kiln or cooler comprises a block 10 of refractory material which tapers from its outer surface 12 to its inner surface 13, and a steel lifter 16 having a flange 17 attached to the block 10 by a bolt or bolts 20, a flange 18 for engagement with mineral being heated or cooled, and a strengthening rib or ribs extending between the flanges. The bolt 20 engages a nut 24 cast within the block 10 or located outside a shell 22 of the kiln or cooler. The shell 22 is cylindrical and holds a number of blocks 10 by dry joints with adjacent blocks owing to their taper. <IMAGE>

Description

SPECIFICATION Rotary kilns and coolers Field of invention The invention relates to rotary kilns and coolers which are suitable for the heating and cooling of particulate matter, for example minerals as part of the extraction of ores and in cement production.

Background art Rotary kilns generally comprise a cylindrical steel shell lined at least in the sections subject to high temperatures with refractory material. From the kiln, hot clinker may pass to a cooler or coolers of similar construction to the kiln. One of the problems is to ensure quick and efficient heat transfer to the materials entering the kiln in order to facilitate reaction and combination, and from materials passing from the kiln to the cooler(s) and thence to other parts of the manufacturing cycle.

It is known to provide lifters for the solid matter in the kiln and cooler(s) by shaping the refractory lining so that on rotation the solid matter is raised towards the upper part and then dropped to allow heat transfer between the solid matter and the air.

Complex sections are required for maximum thermal efficiency and refractory materials are not amenable to shaping in this way. Thus the normal refractory lifter is of compromise shape and simple section, giving some lifting effect which is reduced by wear. Repair in situ is not possible, and replacement costly.

It is also known to use steel lifters, but usually only in the lower temperature zones. Steel used in hotter areas has to be of massive section and highly alloyed.

The invention The invention can be regarded as a combination of the above two kinds of lifter which makes it possible for steel to be used in the hotter sections with consequent ease of maintanence and efficient heat transfer.

The invention provides a lifter assembly for a rotary kiln or cooler which comprises a block of refractory material, tapering down from a large outer surface to a small inner surface, a steel lifter, and means for attaching the lifter to the inner surface of the block.

The block is of relatively low thermal conductivity and reduces heat penetration to the steel of the kiln or cooler.

The block may be cast or formed in a single piece or may be made up from a number of pieces on laying. For example, two similar pieces may be provided with a groove across the middle of a face, and the grooves made to face each other and so generate a cylindrical hole when the pieces are laid. Alternatively, four similar pieces may each be formed with a groove, having as cross-sectional shape a quarter of a circle, along one corner so as to produce a similar hole when the corners of all four pieces are laid together. The inner surface may be shaped to cooperate with the lifter, and the outer surface may be radiused to fit the steel shell of the kiln or cooler.

The means for attaching the lifter may be a steel bolt passing through or nto the block. The bolt may engage a retainer nut or socket cast in the block, or outside the shell of the kiln or cooler, or in an internally -threadetl hole in an outer facing member for the block. Tne lifter may be fabricated or cast of heat-resistant steel and preferably comprises a flange for engagement with the attachment means, a flange fo engaging the mineral being heated or cooled, and a strengthening rib extending between the f anges. A number of slots or holes may be provided in the flange for engagement with bolts, and a number of strengthening ribs may be provided on each lifter. The lifter may be made integral with the attachment means, for example by welding or casting in one piece.Expansion allowances should be made where metal and refractory come intc contact, for example by means of Belville (Trade Mark) washers and/or suitably dimensioning the relevant components.

Lifter assemblies accoiding to the invention may be made of materials known to be suitable for withstanding the operating conditions inside kilns and coolers. The block may be cast of refractory concrete or formed by pressing a refractory mix followed by curing or firing. All re-entrant corners and edges should be radiused to avoid stress concentration.

Lifter assemblies according to the invention may be sold assembled or in their component parts for use in the building, re-lining or maintenance of rotary kilns and coolers. By unfastening the attachment means, a damaged or eroded lifter may be removed without touching the refractory block, and the attachment means and lifter can readily and inexpensively be replaced.

Drawings: Figures 1 and 2 are each a schematic section through an assembly according to the invention in a transverse or radial plane with respect of the kiln or cooler in which it may be laid; and Figure 3 is a plan vievv of a lifter as shown in Figure 1 or 2.

Best mode Each of the assemblies shown in the drawings comprises a block 10 of refractory material which tapers from a large outer surface 12 to a small inner surface 13. A steel lifter 16 comprises a flange 17 for engagement with an attachment bolt 20, a flange 18 for engagement with the mineral being heated or cooled, and a strengthening rib 19 extending between the flanges 17 and 18. The bolt 20 is of steel, and threadingly engages in a nut or socket 24 as indicated in each Figure. A number of blocks 10 are held by dry joints with adjacent blocks owing to their taper.

The assembly of Figure 1 has the bolt 20 extending right through the block 10 and a cylindrical steel shell 22 of the kiln or cooler to the nut 24 which is outside the shell 22. In the block of Figure 2, the bolt 20 only extends to the middle of the block 10, and the nut or socket 24 is in the form of an anchor cast therein.

The lifter shown in Figure 4 has three slots 28 each for engagement with a bolt 20 for attachment to a block 10, and there are four strengthening ribs 19. The number of slots 28, attachment means and strengthening ribs 19 is relatively unimportant and may be varied according to the particular circumstances required on site. The precise shape of the flange 18 and its angle of inclination may be similarly varied depending among other things upon the amount of lift desired for the particulate material being treated or cooled.

Claims

1. A lifter assembly for a rotary kiln or cooler which comprises a block of refractory material, tapering down from a large outer surface to a small inner surface,a steel lifter, and means for attaching the lifter to the inner surface of the block.

2. A lifter assembly according to claim 1 in which the means for attaching the lifter is a bolt passing through or into the block.

3. A lifter assembly according to claim 2 in which the bolt engages a retainer nut or socket cast in the block or outside a shell of the kiln or cooler.

4. A lifter assembly according to any preceding claim in which the lifter comprises a flange for engagement with the attachment means, a flange for engaging the mineral being heated or cooled, and a strengthening rib extending between the flanges.

5. A lifter assembly for a rotary kiln or cooler as herein described with reference to Figures 1 or 2 and 3 of the drawings.