GB2145213A - Improvements in or relating to heat regenerators - Google Patents

Abstract

A refractory checkerwork in a heat regenerator is formed of a plurality of similar bricks arranged in arrays of intersecting co-planar rows, each brick having a body with outwardly projecting tongues on two opposite ends interlocking with adjacent bricks. The body has a width (b) between the other two sides and a thickness (c). The length of projection (d) of each of the tongues is between one-quarter and three-quarters the thickness (c) of the body and each of the tongues is spaced from one of said other sides of the body by a distance (f) at least as great as the dimension (e) of the tongue in the direction of the width (b). <IMAGE>

Description

SPECIFICATION Improvements in or relating to heat regenerators The invention relates to heat regenerators and in particular to regenerators incorporating a brick checkerwork through which hot gases may be passed on one cycle in order to heat the checkerwork and on a subsequent cycle air or other gas is heated by the checkerwork.

Heat regenerators of this type have commonly incorporated a checkerwork formed of refractory bricks. The bricks have been arranged in various ways and the accompanying Figure 2 illustrates one prior art arrangement to provide smooth plain packing of bricks. The checkerwork is arranged to provide a plurality of gas passages through the checkerwork and these passages may extend in a vertical direction or a horizontal direction. In addition to the smooth packing arrangement shown in Figure 2, various brickwork arrays have been used including staggered arrangements of bricks as well as basketweave packing. In some arrangements bricks are spaced from adjacent bricks in the direction along their length so as to allow for expansion.

However, a number of problems arise in the use of checkerwork brick structures in heat recovery generators. For example, when using such heat regenerators in conjunction with glass melting tanks, the brickwork can become coated with dust deposits associated with batch material used for forming glass or the fuels used. These gases and deposits may react with the refractory bricks used in the checkerwork structure and this can cause distortion or collapse of the brickwork. Also condensation of alkali salts within the checkerwork passages can result in blockages, reducing regenerator efficiency and furnace life. In operation of such checkerwork structures regular cleaning may become necessary and this may involve blowing compressed air through the passages, heating the regenerator or, sometimes, mechanical scraping.

It is an object of the present invention to provide an improved refractory brick checkerwork structure and more particularly one in which uniform bricks may be used to provide greater stability of checkerwork structure. Additionally, such improvements in stability allows the use of bricks of reduced thickness giving fuel savings without prejudice to checkerwork stability or life. Furthermore the checkerwork may be arranged to provide gas passageways with reduced likelihood of dust collection.

The present invention provides a brick checkerwork for a heat regenerator. which checkerwork comprises a plurality of rows of interlocking bricks forming a stack extending horizontally and vertically, the stack having a plurality of planar arrays of bricks each planar array comprising intersecting rows of bricks extending perpendicular to each other, characterised in that the bricks in each row are all similar and arranged end to end in straight alignment with, and with the same orientation as, the other bricks in that row, each of said bricks being formed with projecting tongues at opposite ends so that the bricks in one row form interlocking joints with mating tongues of bricks in an intersecting row, the bricks in the intersecting rows of a planar array. being co-planar so that the bricks of all the rows in the array provide a flat surface for engaging an adjacent array.

Preferably a plurality of planar arrays of bricks are stacked together with the rows in one array aligned with the rows in the next array and said flat surfaces of one array abuts a similar flat surface of an adjacent array, whereby a plurality of straight gas passageways of rectangular cross section are provided through the stack each passageway being continuously bounded throughout its length by bricks of successive arrays.

Preferably the bricks each have a body with outwardly projecting tongues on two opposite ends of the brick for use in interlocking with adjacent bricks in a checkerwork, said body having a width (b) between two sides and a thickness (c), the length of projection (d) of each of said tongues being between one-quarter and three-quarters the said thickness (c) of the body and each of said tongues being spaced from one of said sides of the body by a distance (f) at least as great as the dimension (e) of the tongue in the direction of the width (b). The said two ends of the body may be parallel so that the body is of rectangular form. Alternatively the body may have faces at said ends which are tapered inwardly so that the length of the body adjacent the tongues is greater than the length of the body along the side remote from the tongues.The faces at the ends of the body may be inclined at an angle 8 to an adjacent face of a projecting tongue, wherein the angle 8 is greater than 90".

Preferably the said tongues are located adjacent one of the said sides of the body so that the brick is generally T-shaped.

Preferably both tongues are each of the same shape and size and each have the same thickness (c) as the body.

Preferably the projection (d) of each tongue is not greater than half and preferably equals substantially half, the said thickness (c) of the body of the brick. Preferably the dimension (e) of each tongue in the direction of the width (b) is substantially half the width (b) between the said other two sides of the body.

Preferably the brick has plain flat faces.

By provision of a checkerwork as aforesaid, the bricks may be interlocked giving improved stability to the checkerwork. This may result in increased regenerator life by reducing the likelihood of bricks moving out of alignment by twisting or in extreme cases falling out of position so that the packing collapses. By improving stability bricks of reduced thickness may be used safely, improving regenerator efficiency and reducing fuel usage.

An embodiment of the invention will now be described by way of example and with reference to the accompanying drawings in which: Figure 1 is a section through one type of a heat regenerator coupled to a glass melting tank; Figure 2 shows a typical prior art brick checkerwork structure of use in a heat regenerator; Figures 3 and 3A are perspective views of checkerwork structures in accordance with the present invention; Figure 4 is a perspective side view of a refractory brick for use in a checkerwork in accordance with the present invention; Figure 5 is a further perspective view of the brick shown in Figure 4; and Figure 6 shows a plan view of four intersections of bricks arranged in a horizontal array in a checkerwork in accordance with the present invention.

In the arrangement shown in Figure 1, a glass melting tank 11, containing molten glass 12, is connected to a heat regenerator 13 via a plurality of connecting ducts 14. The ducts 14 are spaced along the length of the glass melting tank 11 and interconnect the upper region 15 of the regenerator with ports 16 in the side wall of the glass melting tank. Fuel burners 17 are also located adjacent the ports 16. The regenerator 13 incorporates an array of refractory bricks forming a checkerwork 18 which extends through a substantial part of the height of the regenerator 13 above inlet and outlet ducts 19 at the base of the regenerator and the space 15 at the upper end of the regenerator. In use, gas flow through the regenerator is reversed in a cyclic manner.During one cycle, hot exhaust gases from the glass melting tank 11 are passed through the duct 14 into the upper part of the regenerator 13. The hot gas is passed downwardly through the checkerwork 18 heating up the refractory bricks and is then exhausted through the ducts 19 at the base of the regenerator. In a subsequent cycle, air is allowed to enter the regenerator through the ports 19 so that it passes upwardly through the checkerwork 18 where it is preheated by the hot brickwork and then passes from the space 15 through the ports 16 where it is used for combustion with fuel supplied through the burners 17 so as to heat the contents of the glass melting tank.

This invention is concerned with the refractory bricks and checkerwork used in the heat regenerator 13.

Various packing arrangements of refractory bricks have previously been used in heat regenerators and Figure 2 shows an example of a prior art arrangement. In Figure 2, a smooth plain packing array is shown in which the bricks lie in rows in three mutually perpendicular directions, the bricks in each row being aligned with the remaining bricks in that row so that straight gas passages are provided through the checkerwork. These passages are bounded by smooth brick faces. The checkerwork 18 and bricks used for the present invention are shown more clearly in Figures 3, 3A, 4, 5 and 6. In this checkerwork 18, the bricks are arranged in straight rows lying in three directions mutually perpendicular to each other. As shown in Figure 3, the array is such as to form straight vertically extending gas passageways through the checkerwork.The bricks are all smooth and plain faced so as to provide smooth plain faces bordering the gas passages through the checkerwork. The shape and size of each refractory brick used in the checkerwork is the same and is shown more clearly in Figures 4 and 5. Each refractory brick 20 comprises a rectangular body 21 having outwardly projecting tongues 22 and 23, each of rectangular cross-section, on two opposite ends of the brick. The shape of each brick is symmetrical at both ends. These tongues are for use in interlocking with adjacent bricks in the checkerwork as will be described below. As is shown in Figure 4, the overall length of the brick from the extremities of the tongues 22 and 23 is marked (a). The width of the brick between the other two sides not carrying the tongues is marked (b). The thickness of the brick is marked (c).The length of projection of each of the tongues in the direction of the dimension (a) is marked (d).

The dimension of each tongue 22,23 in the direction of the width (b) is marked (e). Each tongue 22 and 23 is spaced a distance (f) from the side 24 of the brick. In this case each of the tongues 22 and 23 is located flush with the side 25 of the brick so that the brick has a T-shape. The angle 8 between the end face of the brick and the adjacent face of the tongue as shown in Figure 4 is 90 but this may be increased to produce shapes which are easier to construct into a checkerwork as shown in Figure 3A. In such a case each tongue may remain of rectangular shape while the ends of the body 21 taper inwardly on moving towards the side 24 of the brick.

Such bricks 20 are simple to manufacture in basic high alumina and firebrick refractory material and furthermore the bricks are quick and easy to lay in an interlocked design as shown in Figure 3 which provides much greater stability of checkerwork structure. This can increase life of the regenerators in that it avoids twisting of the bricks and reduces the risk of their moving out of alignment and possibly falling out of position. Longer life of the regenerator 13 can result in longer life of the glass tank 11 without the need to shut down the tank. This improved stability further allows the use of narrower bricks with benefit in reduced costs and lower fuel consumption.

The interlocked array is shown most clearly in Figures 3, 3A and 6. The bricks are arranged so that their length along the dimension (a) extends in a number of spaced horizontal rows 26 intersecting with other horizontal rows 27 arranged perpendicular to the rows 26. The bricks are each orientated so that the tongues 22 and 23 project along the horizontal rows. As shown in Figure 3, the horizontal rows 26 are arranged so that the tongues occupy the upper half of each intersection whereas the bricks in the other horizontal rows 27 have the tongues forming the lower half of each intersection. The tongue of each brick at an intersection extends into the thickness of the brick with which it intersects. In this way, the tongues of adjacent bricks in the same row 26 or 27 abut end to end. In this way, each intersection involves end to end placement of four bricks forming the intersection, two from one row 26 and two from one row 27.

This forms an interlocked arrangement in which the upper and lower faces of the bricks in the rows 26 lie flush and co-planar with the respective upper and lower faces of the br1cks in the rows 27 thereby providing a flat plain surface on each planar array of intersecting rows as can be seen from Figure 3 on which a further array of bricks may be positioned. Such arrays are repeated as required to provide a vertical stack of the desired height in the regenerator 13. As can be seen from Figures 3 and 6, such an array provides smooth rectangular gas ducts 29 of square cross-section.

These ducts are continuously bounded by smooth brick faces throughout the height of the stack and the area of the duct is g x g as shown in Figure 6.

Such smooth and continuously bounded gas ducts reduce the possibility of horizontal surfaces on which dust may collect within the regenerator.

In order to achieve the stacking array shown in Figure 3, the length of projection (d) of each tongue 22 and 23 should preferably not exceed one half the thickness (c) of the brick 20. Furthermore, the spacing (f) between each tongue 22 and 23 and the side 24 of the brick 20 should be at least as great as the dimension (e) of each tongue 22,23. In the preferred construction shown in Figure 4, the projection (d) of each tongue 22 and 23 equals substantially half the thickness (c) of the brick 20. F.urthermore the spacing (f) equals the dimension (e) of each tongue 22 and 23. It is therefore apparent that in Figure 4 (e) and (f) are both equal to half (b).

It will be appreciated that in the arrangement described above, all the bricks 20 which are interlocked to form the checkerwork are of the same shape and size. The regenerator may of course incorporate other bricks which are not forming part of the checkerwork in accordance with the invention.

It will be seen that each of the above described bricks basically consists of a rectangular body with plane flat sides, with opposite faces being parallel to each other, each brick having substantially (rectangular cut-away portions at each end of the brick but adjacent one side of the brick only and the cutaway portions extending through the full thickness of the brick. Such cut-away portions thereby provide projecting tongues for interlocking of adjacent bricks in the checkerwork. The cut-away portions may be rectangular or include an angle greater than 90 so as to provide tapered projections for assisting in fitting adjacent bricks into an interlocked array. The checkerwork consists of one or more planar arrays of bricks, each planar array consisting of rows of interlocked bricks, extending in two mutually perpendicular directions, all the bricks in each of said rows being of the same shape and forming interlocked junctions with adjacent bricks in the same row as well as adjacent bricks in the intersecting perpendicular row. All the bricks in the intersecting rows of one planar array lie in the same plane and are not offset perpendicular to the plane so that all the bricks in the planar array provide flat co-planar surfaces on which an adjacent array may be located.

Claims (13)

1. A brick checkerwork for a heat regenerator.

which checkerwork comprises a plurality of rows of interlocking bricks forming a stack extending horizontally and vertically, the stack having a plurality of planar arrays of bricks each planar array comprising intersecting rows of bricks extending perpendicular to each other, characterised in that the bricks in each row are all similar and arranged end to end in straight alignment with, and with the same orientation as, the other bricks in that row, each of said bricks being formed with projecting tongues at opposite ends so that the bricks in one row form interlocking joints with mating tongues of bricks in an intersecting row, the bricks in the intersecting rows of a planar array being co-planar so that the bricks of all the rows in the array provide a flat surface for engaging an adjacent array.

2. A checkerwork according to claim 1 in which plurality of planar arrays of bricks are stacked together with the rows in one array aligned with the rows in the next array and said flat surface of one array abuts a similar flat surface of an adjacent array, whereby a plurality of straight gas passageways of rectangular cross section are provided through the stack each passageway being continuously bounded throughout its length by bricks of successive arrays.

3. A checkerwork according to claim 1 or claim 2 comprising a plurality of bricks each having a body with outwardly projecting tongues on two opposite ends of the brick for use in interlocking with adjacent bricks in a checkerwork, said body having a width (b) between two sides and a thickness (c), the length of projection (d) of each of said tongues being between one-quarter and threequarters the said thickness (c) of the body and each of said tongues being spaced from one of said sides of the body by a distance (f) at least as great as the dimension (e) of the tongue in the direction of the width (b).

4. A checkerwork according to claim 3 in which said tongues are located adjacent one of said sides of the body so that the brick is generally T-shaped.

5. A checkerwork according to claim 3 or claim 4 in which both tongues are of the same shape and size and each have the same thickness (c) as the body.

6. A checkerwork according to any one of the preceding claims in which the projection (d) of each tongue equals half the said thickness (c) of the body of the brick.

7. A checkerwork according to any one of the preceding claims in which the dimension (e) of each tongue in the direction of the width (b) is substantially half the width (b) between the said two sides of the body.

8. A checkerwork according to any one of the preceding claims in which the brick has plain flat faces.

9. A checkerwork according to any one of the preceding claims in which said two sides of the body are parallel and said two ends are parallel so that the body is of rectangular form.

10. A checkerwork according to any one of claims 3 to 8 in which the body has faces at said ends which are tapered inwardly so that the length of the body adjacent the tongues is greater than the length of the body along the side remote from the tongues.

11. A brick checkerwork according to claim 1 in which the said tongues extend horizontally and the horizontal rows of bricks are arranged so that at each intersection between horizontal rows, the bricks in one row are provided with their tongues forming a lower half of the intersections while the bricks in the intersecting row are positioned with their tongues forming the upper halves of the intersections.

12. A checkerwork according to claim 1 or claim 3 in which each brick is symmetrical at each end.

13. A brick checkerwork substantially as hereinbefore described with reference to any one of Figures 3, 3A or 6 of the accompanying drawings.