GB2128172A

GB2128172A - Ceramic tile duct linings

Info

Publication number: GB2128172A
Application number: GB08323841A
Authority: GB
Inventors: Edward Hughes
Original assignee: Anderman & Ryder Ltd
Current assignee: Anderman & Ryder Ltd
Priority date: 1982-09-08
Filing date: 1983-09-06
Publication date: 1984-04-26
Also published as: GB2128172B; GB8323841D0

Abstract

A cylindrical duct having a steel wall 10 is lined with ceramic tiles 11, which are threaded onto rods 12 to form sub-assemblies which are slid into position axially of the housing and interlock by ribs 13 and grooves 14. The rod 12 of each sub-assembly is fastened to the wall 10 by a pair of brackets which are welded to the wall after the sub-assembly has been placed in position. <IMAGE>

Description

SPECIFICATION Ceramic tile linings The present invention relates to ceramic tile linings. It is well known that certain sintered oxide ceramics such as alumina can be used in the form of tiles to produce wear-resistant linings for metal surfaces. It is common practice to glue the tiles to the surface by means of an epoxy adhesive or the like. This is not always satisfactory when the lining is to be used at elevated temperatures since the adhesive has less heat resistance than the material of the tiles.

Another difficulty is that it is very difficult to fabricate large bodies of sintered ceramic with accurate shape and dimensions. Consequently it is necessary to use large numbers of relatively small tiles. This increases the labour required in constructing the lining and where the shape and disposition of the surface being lined imposes limitations of access the placing of the individual tiles may be slow and difficult.

When the shape of the lining is such that the tiles, once assembled, are self-supporting, for example in a lining for a segment of pipe, the necessity for a strong adhesive to hold the tiles in place is less but the reliability of the assembly is reduced. This is because the fracture of a single tile will allow it to fall out and the adjacent tiles will then not be fully supported.

In accordance with the present invention there is provided a ceramic tile lining composed of sub-assemblies each of which comprises a rod carrying a row of tiles with the rod passing through a passage in each of the tiles which lies close to the rear face of the tile.

In such a lining the loss of one tile (which is less likely because a fractured tile can still be held by the rod) does not affect the stability of the whole lining because the other tiles are still supported through the rods which couple them together. The tiles can be glued together side by side to hold them in position in the sub-assembly.

Preferably each rod is mechanically fastened to the wall at spaced points along its length. This is essential where the lining is not self-supporting and is not otherwise secured to the wall. When mechanical attachment of the sub-assembly is used this may be supplemented by the application of adhesive between the tiles and the wall.

The fastening of the rod to the wall can conveniently be effected by brackets each of which has a foot welded to the wall and a leg formed with an opening through which the rod passes. Preferably two brackets are placed close to the ends of a rod and the free ends of the rod, which project beyond the brackets are accommodated in passages in two end tiles. These end tiles may be recessed to fit around both the welded foot and the leg of the brackets. They may also be specially shaped to form a junction with the end of a further sub-assembly where the wall changes direction or is shaped to require a change in the direction of the tiling.

The invention is particularly advantageous for lining ducting where the overall dimensions of the ducting impose severe limits on access. For example a cylindrical pipe or duct, with a diameter of less than one metre, especially one which changes direction along its length, would be extremely difficult to line by the placing of individual tiles. However the use of sub-assemblies in accordance with the invention with the rods running parallel to the axis of the duct makes it possible to line each section of a duct with a number of subassemblies which are of the same length as the duct.

The invention will now be described in more detail with the aid of an example illustrated in the accompanying drawings, in which Figure 1 is a perspective view of a duct lining in accordance with the invention with parts removed to show details of the construction, Figure 2 is a perspective view of a subassembly used in the lining of Fig. 1, Figure 3 is a plan view of a sub-assembly similar to that of Fig. 2 on an enlarged scale, and Figure 4 is a perspective view of a single tile.

Referring first to Fig. 1, the lining shown is for a length of ducting having a cylindrical steel wall 10. The lining is made up of a multiplicity of individual ceramic tiles 11 but these are grouped into sub-assemblies each consisting of a number of tiles 11 threaded onto a rod 12. The rods 12 extend parallel to the axis of the ducting and are conveniently of a length corresponding to that of a straight section of the ducting. The sub-assemblies can be inserted in the ducting by sliding them in axially and they interlock by virtue of each tile having radial side faces which are formed with a rib 13 on one side and a mating groove 14 on the other side. After a subassembly has been placed in position its rod 12 is secured to the wall 10 by welding brackets to the wall.

Figs. 2 and 3 show a single sub-assembly consisting of a rod 12 with tiles 11 and two brackets 15 and 16 each of which is an angle bracket with an aperture 17 in one limb to fit over the rod 12 and an aperture 18 in the other limb to facilitate welding of the bracket to the wall 10. As seen in Fig. 4 each of the tiles 11 is conveniently of the same shape with a passage 19 for the rod 12 which lie close to the rear face 20 of the tile, being the face which lies adjacent the wall 10. The rib 13 and groove 14 are formed in side faces of the tile and the end faces of each tile are those which lie against the end faces of adjacent tiles. It will be noted that the passage 19 is formed in a block 21 integral with the tile which is recessed below the rear face 20 and the two end faces of the tile to accommodate a bracket 15 or 16 when the tile is adjacent one of these brackets.

In constructing each sub-assembly the tiles 11 are placed on the rod 12 and their end faces are secured to one another with adhesive to ensure the correct orientation. The brackets 15 and 16 are placed on the ends of the rod before the end tiles are placed in position, though of course other brackets may be inserted between tiles at intervals along the rod 12 if required. As shown in Fig. 3 the end tiles 22 and 23 have inclined end faces 24 and 25, respectively, to enable them to engage the end tiles of a further section of lining whose axis is not aligned with that of the section shown. In this way changes in the direction of the ducting can be accommodated.

In a specific example of the lining of a duct with a lining constructed in accordance with the invention each of a row of tiles forming the sub-assembly has an inner radius of 270 mm, corresponding to the size of the flow cross-section within the completed lining, and an outer radius of 295 mm. The axial thickness of each tile is 30 mm and the end faces are parallel to each other. The side faces of each tile are radial and thus inclined to each other at 12 making the rear or outer face of the tile (which lies against the wall of the duct) wider than the front or inner face.

A bore of 8 mm diameter runs parallel to the axis of the duct with its centre spaced 18 mm from the front face of the tile and located centrally between the side faces. The rear face of the tile has in alignment with the bore a shallow groove of about 1 mm depth and 12 mm width.

A number of such individual tiles, for example nine tiles, are mounted on a steel rod which fits in the bores of the tiles and projects at each end. The end faces of the tiles are glued together with an epoxy resin adhesive to hold them in the correct relative positions.

At each end of the sub-assembly an angle bracket having a hole in one limb of 8 mm diameter is fitted over the end of the rod. The end faces of the tiles are recessed to accommodate this limb of the bracket. The other limb of each bracket is welded to the steel wall of the duct after the sub-assembly has been placed in position. Thirty of such subassemblies are placed parallel to one another around the periphery of the duct so that in addition to the brackets which hold the individual sub-assemblies the complete assembly is wedged in position and no tile can fall inwards.

The ends of the rod project beyond the mounting brackets and are received in bores in end tiles which are subsequently glued in position. Whereas the other tiles in the row can be of identical shape, the end tiles are in the first place recessed to fit around the limb of the bracket which is welded to the wall. In the second place, where the duct changes direction the outer end face of the end tile may be inclined to form a corner with the lining of the adjacent portion of the duct. For this purpose a complex curvature of the end face may be required.

The above example of a lining is designed for use in steel ducting in power station construction where the inside of the duct is exposed to erosion by coal and coal dust passing through the duct. The steel of the duct wall would be rapidly worn away under these conditions but an alumina ceramic of 97.5% purity with a density of not less than 3780 Kg/m-3 (sold under the trade name DERANOX) provides good wear resistance.

Claims

1. A ceramic tile lining composed of subassemblies each of which comprises a rod carrying a row of tiles with the rod passing through a passage in each of the tiles which lies close to the rear face of the tile.

2. A lining as claimed in claim 1 in which the rod is mechanically fastened to the wall at spaced points along its length.

3. A lining as claimed in claim 2 in which the mechanical fastening of the rod to the wall is effected by brackets which are welded to the wall, each bracket having an aperture for the passage of the rod.

4. A lining as claimed in claim 3 in which each sub-assembly has a bracket close to each end extending between the end tile and the adjacent tile.

5. A lining as claimed in any of the preceding claims in which the tiles in each subassembly have their end faces glued to the end faces of adjacent tiles of the sub-assembly.

6. A lining as claimed in any of the preceding claims in which the tiles are secured to the wall by adhesive.

7. A lining as claimed in any of the preceding claims in which the side faces of the tiles, which form the sides of each sub-assembly, have a rib on one side face and a mating groove on the other side face to enable the sides of the sub-assembly to be interlocked.

8. A lining as claimed in any of the preceding claims formed as a lining for a length of ducting.