GB2233079A - Refractory lining of furnaces - Google Patents

Abstract

So that the refractory elements (22) in the shell (18) of a rotary kiln or cooler can be sintered before use, the retaining means comprise a plurality of, preferably symmetrically paired or bifurcated metal clamping members (26) each adapted for location in a slot (24) in a refractory element (22) such that, as a nut (32) is tightened on a bolt or stud (28) the or each inwardly extending arm of the member (26) is deformed by tapering walls of the slot (24). <IMAGE>

Description

Refractory lining of furnaces.

The invention relates to the refractory lining of kilns and furnaces, in particular of rotary kilns of the kind used in cement production.

It is known to line a kiln, cooler or parts thereof by the use of pre-fabricated refractory anchoring elements, metal ancbg i,g inettlbers being cast into said refractory elements and acting to hold said refractory elements against the interior surface of the metal shell of the kiln. When said refractory anchoring elements have been fixed in position, a monolithic mass of refractory material has been applied to fill the spaces between said elements.

This known metnod of lining works reasonably well but suffers from one particular disadvantage, this being that since the metal clamping members are cast into the refractory elements the latter cannot be sintered before being used because firing at high temperature would destroy the metal clamping members.

The invention has for its object to provide a means for retaining pre-shaped refractory anchoring elements in a rotary furnace whereby said refractory elements can be sintered before use.

According to the invention, there is provided a means for retaining pre-shaped and fired refractory anchoring elements in the shell of a rotary kiln or cooler, said means comprising a plurality of bifurcated metal clamping members each adapted for location within a rectangular section slot in a respective anchoring element, the form of each bifurcated metal clamping member being such that as a respective nut at the exterior of the furnace is tightened on the protruding end of a bolt or stud extending through an apertured cross piece of the clamping member, said cross piece is drawn down to abut the inner surface of the steel shell of the kiln, the inwardly extending arms of the member being inwardly deformed by the tapering walls of the slot in the. refractory anchoring element concerned, the arrangement being such that an excessive tightening of the nut will merely result in the apertured cross piece being clamped even tighter against the interior surface of the steel shell of the furnace and no excessive stress will be imposed on the mass of refractory material of the anchoring element. The rectangular section slot in each anchoring element may extend completely through the element or may be in the form of a slot extending across the surface which is to abut the inner surface of the steel shell. Each bifurcated metal clamping member may be made from a single length of metal strip or may be constituted by a pair of clamping members nested one on the other.

If each bifurcated metal clamping member is constituted by a pair of one armed clamping members nested one on the other, a metal washer may overlie tY'L clamping membev.c to a=.ly pressure thereto to cause their upwardly extending arms to apply pressure to the anchoring element in which they are located. Alternatively, a pair of eccentric elements may be provided for rotation on the bolt or stud concerned, the arrangement being such that having been placed on the bolt or stud in a relatively narrow condition the pair of eccentric elements can be moved relative to each other to fill the available space between the arms of the pair of clamping members.In this latter case, resilient means may be provided for moving the eccentric elements relative to each other to fill the available space between the arms of the pair of clamping members. A 'Belville' spring washer will preferably be provided beneath a nut which engages each bolt or stud. A lifter may be associated with at least some of the pre-shaped refractory anchoring elements, each lifter being a heat resisting steel lifter comprising a flange for abutment with the anchoring element, a further flange for engaging the pieces of solid matter being progressed through the kiln, and a strengthening rib extending between the two flanges.In this case, a connector for attaching the lifter to the .refractory lining may be a bolt passing through a hole in the flange which abuts against the refractory anchoring element, the bolt engaging a screwthreaded sleeve which is connected to a screwthreaded stud forming part of the clamping arrangement- by means of which the anchoring element is clamped in position against the interior surface of the steel shell of the kiln.

In order that the invention may be fully understood and readily carried into effect, the same will now be described, by way of example only, with reference to the accompanying drawings, of which: - Figure 1 is a part sectional view of a cement rotary kiln, Figure 2 is a view drawn to a somewhat larger scale than Figure 1, on the line 2-2 in Figure 1, of a portion of one of a number of coolers leading from the kiln, Figure 3 is a sectional view through a pre-shaped and fired refractory anchoring element and clamping arrangement embodying the invention, Figure 4 is a view in the direction of arrow 4 in Figure 3, and Figures 5 to 16 are views which illustrate various possible modifications.

Referring now to Figure 1, the cement rotary k@@n there illustrated has a quantity of planetary or satellite coolers 12, into which falls hot clinker from the process through outlet ports 14 via cooler elbows 16. The coolers 12 each consist of a sheet steel shell 18 with, at the hottest section, a refractory lining generally indicated 20.

The refractory lining in this zone of the cooler is conventionally- lined with pre-shaped pieces which may be cured or fired and differing shapes may be combined to form cam linings to aid in heat transfer between hot exiting clinker and cool entering air for the process.

In sections of the cooler where less regular contours are encountered such as the elbows or bends themselves the conventional lining technique involves the use of heat resisting metal anchoring shapes, for example of Y or V section which are welded in position and cast, poured or tamped refractory installed around the anchors. The whole is returned to service after time has been allowed for drying and setting or curing of the monolithic lining.

Fairly satisfactory performances have been achieved with this type of lining as the technology of monolithic refractories improves. However, in cases where preferential wear takes place, for example where clinker exiting the kiln continually impacts upon one confined area of a cooler lining commonly called a target area, excess wear occurs and the refractory in this relatively small area may be lost. Since repair with this technique is difficult, it is usually necessary to replace the whole of the lining.

In carrying out this invention, as indicated in Figure 2, the refractory lining includes a plurality of pre-shaped and cured or fired refractory anchoring elements 22 which in those parts of the structure which are of irregular contour there is used a cast poured or tamped refractory placed between the anchoring elements.

In this situation the general shape of the refractory anchoring element used is as indicated in Figures 3 and 4, a laterally stretched frustoconical block adapted to be clamped in position with its smaller end surface in contact with the inner surface of the steel shell. A tapering rectangular section slot 24 extends completely through the anchoring element as shown.

In other parts where the section is regular or substantially regular in contour the refractory lining can be constituted from pre-shaped and cured or fired pieces which f s; toc,ez.her and support 3a > h other, the metal clamping members being bolted in position to complete the support adjacent to a particular area, such as one referred to earlier as a target area; this relatively small area can be removed when worn and replaced quickly without disturbing the remainder of the lining in any way.

Where a change in section occurs in a generally regular structure, clamping members are bolted in position to support adjacent prefired or cured shapes and the clamping members when set in position are protected against the furnace environment when in service by the installation of in-situ cast, poured or tamped refractory around them.

The clamping arrangement by means of which the anchoring element is clamped in position against the interior surface of the steel shell, or by means of which adjacent pre-fired or cured shapes are supported in position is constituted by a bifurcated metal clamping member 26 which is located within the rectangular section slot 24 of the anchoring element, or is bolted in position adjacent to pre-fired or cured refractory shapes.

An apertured cross piece of the clamping member is tightly clamped against the interior surface of the steel shell by means of a bolt 28 which extends through a hole in the shell and which is provided on the exterior of the shell with a 'Belville' spring washer 30 and nut 32. The form of the bifurcated metal clamping member is such that as the nut 32 is tightened so that the apertured cross piece of the member is drawn down to abut the interior surface of the steel shell, the upwardly extending arms of the member are inwardly deformed by the walls of the slot in the anchoring element.

It will thus be understood that an excessive tightening of the nut will merely result in the apertured cross piece being clamped even tighter against the interior surface of the steel shell, and no excessive stress will be imposed on the mass of refractory material of the anchoring element.

The clamping arrangement will be set in position, and protected against the furnace temperature when in service, by the application of in-situ cast, poured or tamped refractory material to fill the slot 24 in the anchoring element.

It will be understood that since the refractory anchoring elements are manufactured quite separately from the metal clamping members, it is possible to fire the refractory anchoring elements so that they become sintered before use. This is advantageolls R because a rc-sintered refractory anchoring element will not change its shape or crack as the kiln lining of which it forms a part is brought up to the required operating temperature.

In Figures 5 to 9 there is illustrated a modification of the clamping arrangement just described, the modification residing in the fact bhat the bifurcated fil.!t.ping member thus been replaced by a pair of one armed clamping members 34 and 36 nested one on the other, as shown. A large metal washer 38 overlies the clamping members to apply the clamping pressure thereto and to cause their upwardly extending arms to apply pressure to the anchoring element in which they are located or exactly to fit within the tapering rectangular slot 24, whilst applying the desired proportion of clamping pressure to the upwardly extending arms 34 and 36.It will also be clear that either member of the clamping pair can be used alone along with an overlying washer, bolt, nut and "Belville" washer for use as anchors to fix tapering, preshaped and fired, or cured pieces in position, supporting neighbouring shapes which thus support each other in substantially regularly contoured areas, where target areas occur, or where sharp changes of section occur in generally regular structures. As in the case of the previously described embodiment, after being tightened in position, the clamping arrangement will be set in that position, and protected against the furnace environment when in service, by the application of in-situ cast, poured or tamped refractory to fill the slot 24 in the anchoring element or to cover over upwardly extending arms 34 or 36, or both of them as shown in Figures 5 and 6.Here again the arrangement is such that the refractory anchoring elements have been able to be completely dried and sintered by firing before having been secured in position in the kiln concerned.

A selection of the large metal washers 38 referred to above may be provided, varying in their width so that they can be used selectively according to the width of the slot in the preshaped refractory anchoring element concerned or according to the amount of clamping force it is desired to apply to the single member of the clamping pair acting against an endmost one of a number of refractory shapes.

In Figures 10 ,and 11 there is illustrated another possible clamping arrangement which in this instance is constituted by a pair of eccentric elements 56 pd 58 whizz ere positioned or the bolt 28, one overlying the other. The eccentric elements could be of flat plate form but in the drawings are shown to be provided with peripheral flange portions 57 and 59 respectively which can seat more effectively against the opposed surfaces of the pair of clamping members 34 and 36. The arrangement is such that, having been placed on the bolt in the condition shown in fuil lix.~s il Figure 11, the eccentric elements can be rotated in opposite direction to increase the effective overall width of the pair of elements. the eccentric shape of said elements produces a wedging action between their upstanding flange portions and the surfaces of the pair of clamping members 34 and 36. The bolt 28 can then be tightened to secure the elements in position. After being tightened, the clamping arrangement will of course be set in position, and protected against the furnace environment when in service, by the application of in-situ cast, poured or tamped refractory.

A further variation of the clamping arrangement just described could involve the provision of resilient means, for example a coil spring, for urging the eccentric members towards their widest setting. The pair.of elements could then be placed on the bolt in their narrowest setting so that when released they will spring outwards to the fullest extent allowed by the spacing of the clamping members 34 and 36.

Referring now to Figure 12, the further modification there illustrated is the addition of a lifter assembly, generally indicated 40, to one of the plurality- of pre-shaped refractory anchoring elements.

It is known to provide lifters for the solid matter in a rotary kiln by shaping the refractory lining so that on rotation of the kiln the solid matter is raised and then dropped to promote heat transfer between the solid matter and the air.

However, the lifter in the present case is a steel lifter 42 comprising a flange 44 for abutment with the pre-shaped refractory anchoring element, a further flange 46 for engaging the pieces of solid matter being progressed through the kiln, and a strengthening rib 48 extending between the two flanges. A connector for attaching the lifter to the refractory lining is a bolt 50 passing through a hole in the flange 44 and engaging a screwthreaded sleeve 52 which is connected to a screwthreaded stud 54 forming part of the clamping arrangement by means of which the anchoring element has b clamped in position against the interior surface of the steel shell of the kiln.

It will be understood that the number of lifters provided in the complete kiln can be varied. Only a selected number of the pre-shaped refractory anchoring elements may be provided with such lifters. It will also be understood that the precise shape of each lifter may be varied.

Various other modifications may be provided. For example, in Figure 13, there is illustrated an arrangement in which a plurality of the pre-formed and fired anchoring elements provided with bifurcated metal clamping members have tongue and groove engagement with other pre-shaped pieces located between them.

Figure 14 illustrates the way in which the metal clamping members can be used to abut the endmost pre-shaped and fired refractory elements in those regions which are not cylindrical. When the clamping members have been tightened, the spaces in which they are located can be filled with a cast, poured or tamped refractory material.

Referring now to Figures 15 and 16, these illustrate a modified form of pre-shaped refractory anchoring element. As shown, the exterior shape of the element is still that of a laterally stretched frusto-conical block. However, the tapering rectangular section slot 124 which is formed therein does not extend through the element as in the element illustrated in Figures 3 and 4 but extends across the smaller end surface which in use of the element is to contact the interior surface of the steel shell. The bifurcated metal clamping member 26 (or pair of clamping members 34 and 36 substantially as shown in Figures 5 to 11) is in this case located within the slot, substantially centrally of the pre-shaped element where the slot is locally widened, by sliding it along the slot from one end, as shown.

This modified form of pre-shaped refractory anchoring element may be particularly advantageous in certain situations, for example where the part of the steel shell to be lined is vertical or substantially vertical. In this case the anchoring element can be installed as shown in Figures 15 and 16 so that, when the metal clamping member has been tightened, refractory material can be poured into the upper end of the slot in the element.

A further possible modification of the refractory anchoring element illustrated in Figures 15 and 16 would be to blank off one end of the slot 124. In other words, in use of the element, the upper end on).y of ti? slot would be open for vh.2 pouring of refractory material thereinto.

Thus there is provided a means whereby a rotary kiln can be lined in a very convenient manner and whereby any re-lining or repair can very easily be carried out. When an area of the lining needs to be repaired, the damaged lining in that region can quite simply be removed by loosening the nuts 32 from the bolts or studs which secure the preshaped refractory anchoring elements in that region and then imparting heavy impacts to the projecting bolts or studs. The lining is thereby ruptured along lines which lie between those anchoring elements and other anchoring elements in undamaged parts of the lining.

Claims (10)

CLAIMS:

1. Means for retaining pre-shaped and fired refractory anchoring elements in the shell of a rotary kiln or cooler, said means comprising a plurality of bifurcated metal clamping members each adapted for location within a rectangular section slot in a respective anchoring element, the form of each bifurcated metal clamping member being such that as a respective nut at the exterior of the furnace is tightened on the protruding end of a bolt or stud extending through an apertured cross piece of the clamping member, said cross piece is drawn down to abut the inner surface of the steel shell of the kiln, the inwardly extending arms of the member being inwardly deformed by the tapering walls of the slot in the refractory anchoring element concerned, the arrangement being such that an excessive tightening of the nut will merely result in the apertured cross piece being clamped even tighter against the interior surface of the steel shell of the furnace and no excessive stress will be imposed on the mass of refractory material of the anchoring element.

2. Means according to claim 1, in which the rectangular section slot in each anchoring element is in the form of a slot extending across the surface which is to abut the inner surface of the steel shell.

3. Means according to either one of the preceding claims, in which each bifurcated metal clamping member is made from a single length of metal strip or is constituted by a pair of clamping members nested -one on ^ he the

4. Means according to claim 3, in which each bifurcated metal clamping member is constituted by a pair of one armed clamping members nested one on the other, a metal washer overlying the clamping members to apply pressure thereto to cause their upwardly extending arms to apply pressure to the anchoring element in which they are located.

5. Means according to claim 3, in which each bifurcated metal clamping member is constituted by a pair of one armed clamping members nested one on the other, a pair of eccentric elements being provided for rotation on the bolt or stud concerned, the arrangement being such that having been placed on the bolt or stud in a relatively narrow condition the pair of eccentric elements can be moved relative to each other to fill the available space between the arms of the pair of clamping members.

6. Means according to claim 5, in which resilient means are provided for moving the eccentric elements relative to each other to fill the available space between the arms of the pair of clamping members.

7. Means according to any one of the preceding claims, in which a 1Belville' spring washer is provided beneath a nut which engages each bolt or stud.

8. Means according to.any one of the preceding claims, in which a lifter is associated with at least some of the pre-shaped refractory anchoring elements, each lifter being a heat resisting steel lifter comprising a flange for abutment with the anchoring element, a further flange for engaging the pieces of solid matter being progressed through the kiln, and a strengthening rib extending between the two flanges.

9. Means according to claim 8, in which a connector for attaching the lifter to the refractory lining is a bolt passing through a hole in the flange which abuts against the refractory anchoring element, the bolt engaging a screwthreaded sleeve which. is' connected to a screwthreaded stud forming part of the clamping arrangement by means of which the anchoring element is clamped in position against the interior surface of the steel shell of the kiln.

10. Means for retaining pre-shaped and fired refractory anchoring element in the shell of a rotary kiln or cooler, said means being constructed, arranged and adapted to be used substantially as hereinbefore described with reference to and as illustrated by the ccoman'7ing drawings.