Refractory burner brick

Abstract

A refractory furnace brick (1/2) has chamfered corner faces (F3/f3) enabling the bricks to be formed into a regular grid with longitudinal rectangular bores formed both within respective bricks and defined by surrounding bricks. Preferably the shorter sidewalls of the bricks are extended slightly in the transverse direction to form ridges R/R′ which interlock to strengthen the structure. In order to provide a distributed expansion flexible ceramic pads (P) may be provided between the chamfered corner faces.

Description

The present invention relates to a refractory furnace brick and to burners utilizing a grid of such bricks e.g. in blast furnaces and the like.

Conventional blast furnace stoves utilize burners made up of successive courses of bricks, each course comprising bricks of different sizes, the courses forming overlapping grids which facilitate combustion of the furnace gases.

Such burners are subjected to extremely high temperatures and are also impacted by solid debris which can result in failure, particularly of the smaller bricks.

An object of the present invention is to provide a simpler construction which can overcome or alleviate at least some of the above disadvantages.

The present invention provides a refractory furnace brick having a longitudinal central bore surrounded by sidewalls, the brick having a transverse cross-section in which corner regions of the junctions of the sidewalls are shaped externally to interface with external corner regions of neighbouring furnace bricks when disposed in a regular two dimensional grid of such bricks.

An advantage of such a construction is that relatively small bricks which are correspondingly more susceptible to breakage can be eliminated. Furthermore the manufacturing requirements are simplified.

Preferably said corner regions are chamfered to form mating faces. The chamfering reduces the pressure at the interfacial regions, thereby reducing the risk of fracturing of the bricks, and also stabilizes the arrangement.

Preferably the interfacial regions comprise ridge portions which can interlock with the ridge portions of neighbouring bricks in said regular two dimensional grid. This feature further stabilizes the construction and obviates the requirement for cement joints.

Preferably the refractory furnace brick is so shaped and dimensioned that the transverse cross-section of said upright central bore is substantially the same as that of each neighbouring bore defined by the spacing between opposed external brick surfaces in such a regular two dimensional grid. This feature ensures that the grid openings are of a uniform size and facilitates good combustion.

Preferably the area of said transverse cross-section of said upright central bore is within ±20% of that of each said neighbouring bore. More preferably each dimension of said transverse cross-section of said upright central bore is within ±10% of the corresponding dimension of said neighbouring bore.

Further preferred features are defined in the dependent claims.

A preferred embodiment of the invention is described below by way of example only with reference to FIGS. 1 to 8 of the accompanying drawings, wherein:

FIG. 1 is a perspective view from below of a refractory furnace brick in accordance with the invention and intended for use in the top capping course of a burner;

FIG. 2 is a perspective view from below of a further refractory furnace brick in accordance with the invention which is intended for use in the capping course immediately beneath the top capping course of a burner;

FIG. 3 is a perspective view from below of the furnace brick of FIG. 1 showing one half cut away in order to reveal the longitudinal cross-section of each of the longer sidewalls;

FIG. 4 is a perspective view from below showing the top two capping courses of a burner utilizing the furnace bricks of FIGS. 1 and 3 and FIG. 2;

FIG. 5 is a diagrammatic horizontal section of either of the capping courses in FIG. 4;

FIG. 5A is a magnified view of the interfacial region of the two furnace bricks shown in FIG. 5;

FIG. 6 is a longitudinal diametrical cross-section through a furnace utilizing the capping courses shown in FIG. 4;

FIG. 6A is a magnified partial view showing the gap between the outer wall of the furnace and the burner grid of FIG. 6;

FIG. 7 is a transverse cross-section through the upper capping course of FIG. 6; and

FIG. 8 is a transverse cross-section through the lower capping course of FIG. 6.

Referring to FIG. 1, the refractory furnace brick 1 is substantially rectangular in cross-section and has a substantially rectangular upright central bore A as shown. The two longer sidewalls have rounded ridge portions R1 which project beyond flat faces F4 at the bottom of the two shorter sidewalls. The longer sidewalls have external faces F1 which define substantially rectangular bores between the bricks when disposed in a grid as described below with reference to FIG. 4. The outer faces F2 of the shorter sidewalls constitute the other internal faces of the neighbouring bores in the grid as will become apparent from FIG. 4.

It will be noted that the shorter sidewalls have longitudinal ridges R whose extremities are defined by faces F2. The upright longitudinal edges of these ridges enable the furnace bridge to interlock when assembled into a grid, and lie adjacent chamfered surfaces F3 at the four corners of the block which interface with the chamfered corners of neighbouring bricks as will become apparent from the discussion of FIG. 5 below.

As best seen in FIG. 3, all four sidewalls are tapered in transverse cross-section at their upper extremities to form ridges R2 which are also shown in FIG. 4.

The refractory furnace brick 2 showing in FIG. 2 is intended to be assembled into a grid supporting an upper capping course composed of bricks 1 and it will be noted that the longer sidewalls and upper ridges r1 which are similar to ridges R1 of brick 1 and that the shorter sidewalls have upper end faces f4 which are similar to flat faces F4 of furnace brick 1. As will become apparent from FIG. 4, when the furnace bricks 1 are inverted they can be placed on the furnace bricks 2 with the ridges R1 sitting on end faces f4 and the ridges r1 contacting the faces F4. This arrangement enables the upper capping course to be displaced horizontally relative to the lower capping course as necessary since there is no interlocking between the flat faces f4/F4 and the ridges R1/r1. The lower end portions of the sidewalls have flat faces (not shown) unlike the ridged portions of the bricks 1 since they rest on flat surfaces of a lower grid. The bricks 2 are otherwise similar to the bricks 1, in particular by including external sidewall faces f1 and f2 which define neighoburing bores in the lower grid of FIG. 4, by incorporating a ridge R′ similar to the ridge R of brick 1 which ensures interlocking between neighbouring bricks and by incorporating chamfered mating surfaces f3 at the respective corners.

Turning now to FIG. 4, it will be seen that an upper layer of furnace bricks 1 can be assembled to form a regular grid with each brick contacting neighbouring bricks as its chamfered faces F3 and at the edge portions of its ridges R, and that the bricks 2 of the lower grid similarly define a lower grid.

It will be seen that the two grids are mutually offset by half a brick width along the direction of the shorter sidewalls, enabling airstreams a and gas streams b to be bifurcated and mixed to ensure efficient combustion.

In order to provide a distributed expansion allowance, the chamfered faces F3/f3 of the bricks 1/2 are spaced apart by ceramic fiber pads P having a thickness e.g. 1.5 mm to 2 mm corresponding to the brick spacing as best seen in FIG. 5A. These pads are relatively thin compared to the height of the ridges R, again as best seen in FIG. 5A and hence do not prevent interlocking between the sides of the ridges and the faces F1/f1.

FIG. 6 shows the complete burner in cross-section, which is typically part of a blast furnace or other high temperature combustion unit. As shown in FIG. 6A, a further expansion gap G is provided at the periphery of the burner grid. The tapered upper extremities of the sidewalls prevent debris from catching on the grid walls which might otherwise lock the grid openings. The tapered lower extremities of the furnace bricks 1 facilitate a smooth gas flow through the burner assembly.

As best seen in FIG. 7, the bores A within the interior of the respective bricks 1 are of essentially the same transverse cross-section as the bores B defined by the faces F1 and F2 of surrounding bricks. The corners of the bores A are however rounded slightly to avoid weak points at these regions.

The outer bricks are cut in half where necessary in order to provide a roughly circular shape which can be confined within the outer walls W of the burner.

FIG. 8 shows a similar arrangement of the furnace bricks 2 of the lower grid and again it will be seen that the bores A′ are of a similar transverse cross-section to the bores B′ defined by the faces f1 and f2 of surrounding bricks 2.

In a ceramic burner (as described above) the composition of the firebricks is suitably as follows:

Firebrick Option (brick   Monolithic Option (brick
formed by pressing)       formed by moulding)
Chemical Analysis         Chemical Analysis
Al2O3 - 61.5%             Al2O3 - 60%
SiO2 - 34%                CaO - 1.9%
Fe2O3 - 1.2%              Fe2O3 - 1.4%
Bulk Density - 2450 kg/m3 Bulk Density - 2420 kg/m3

The bricks of the invention can also be used in units such as:

• • Acid Drying Towers,
  • Thermal Oxidisers,
  • Blast Furnace Stoves,
  • Reactor Vessels.

In these applications the following compositions are suitable:

Firebrick Option (brick          Monolithic Option (brick
formed by pressing)              formed by moulding)
Chemical Analysis                Chemical Analysis
Al2O3 - 42 to 80.5%              Al2O3 - 39 to 98%
SiO2 - 53 to 11.8%               CaO - 3.2 to 1.4%
Fe2O3 - 2 to 1.6%                Fe2O3 - 2.3 to 0.1%
Bulk Density - 2220 to 2780 kg/m3 Bulk Density - 2250 to 3100 kg/m3

The above compositions are exemplary and not limiting.

Claims

1. A refractory furnace brick comprising:

a plurality of sidewalls having facing internal surfaces defining a longitudinal central bore of said furnace brick, said sidewalls having longitudinal junctions,

said furnace brick having a transverse cross-section in which said longitudinal junctions form corner regions thereof, said corner regions being shaped externally to interlock with similar corner regions of neighbouring furnace bricks when said furnace brick is disposed in a regular two-dimensional transversely-extending array of such furnace bricks.

2. A refractory furnace brick as claimed in claim 1, wherein said corner regions have chamfered portions which form mating faces in said regular two-dimensional array.

3. A refractory furnace brick according to claim 1, wherein said junctions comprise external longitudinally-extending ridge portions which interlock transversely with similar ridge portions of neighbouring furnace bricks in said two-dimensional array.

4. A refractory furnace brick according to claim 1, wherein said sidewalls have longitudinal ends lying in a common transverse plane.

5. A refractory furnace brick according to claim 1, wherein said array includes adjacent furnace bricks having facing external surfaces, said facing external surfaces defining a further longitudinal bore, said facing external surfaces matching said facing internal surfaces whereby the transverse cross-sections of said longitudinal central bore and asid further longitudinal bore are substantially the same.

6. A refractory furnace brick according to claim 5, wherein said transverse cross-section of said longitudinal central bore has an area within ±20 percent of the area of said further longitudinal bore.

7. A refractory furnace brick according to claim 5, wherein said longitudinal central bore and said further longitudinal bore have matching dimensions such that said longitudinal central bore has dimensions which are each within ±10 percent of said matching dimensions of said further longitudinal bore.

8. A refractory furnace brick according to claim 1, comprising a first pair of opposite sidewalls, said opposite sidewalls having ends which are tapered in longitudinal cross-section.

9. A refractory furnace brick according to claim 8, comprising a second pair of opposite sidewalls having flat end surfaces, said first pair of opposite sidewalls extending beyond said flat end surfaces of said second pair of opposite sidewalls.

10. A refractory furnace brick according to claim 8, wherein said first pair of opposite sidewalls each have opposite ends which are both tapered in longitudinal cross-section.

11. A refractory furnace brick according to claim 1, which is substantially rectangular in transverse cross-section.

12. A transversely-extending grid of refractory furnace bricks, said bricks having a plurality of sidewalls having facing internal surfaces defining longitudinal central bores, said sidewalls having longitudinal junctions, said longitundinal junctions having an external transverse cross-section which interlocks tranversely with longitudinal junctions of neighbouring furnace bricks in the grid.

13. A transversely-extending grid according to claim 12, wherein said longitudinal junctions are chamfered in transverse cross-section to form mating interfaces between said neighbouring furnace bricks.

14. A transversely-extending grid according to cliam 12, wherein said mating interfaces include interlocking longitudinally-extending ridge portions.

15. A transversely-extending grid according to claim 12, wherein said longitudinal junctions have interlocking portions separated by resilient refractory pads.

16. A transversely-extending grid according to claim 12, wherein adjacent furnace bricks have facing external surfaces, said facing external surfaces defining further longitudinal bores, said facing external surfaces matching said facing internal surfaces whereby the transverse cross-sections of said longitudinal central bores and said further longitudinal bores are substantially the same.

17. A transversely-extending grid according to claim 16, wherein said transverse cross-sections of said longitudinal central bores have an area within ±20 percent of the area of said further longitudinal bores.

18. A transversely-extending grid according to claim 16, wherein said longitudinal central bores and said further longitudinal bores have matching dimensions such that said longitudinal central bores have dimensions which are each within ±10 percent of said matching dimensions of said further longitudinal bores.

19. A grid comprising two vertically adjacent layers of furnace bricks, said bricks having a plurality of sidewalls having facing internal surfaces defining upright central bores, said sidewalls having substantially vertical junctions, said junctions having external horizontal cross-sections which interlock tranversely with substantially vertical junctions of neighbouring furnace bricks in the same layer, said layers being relatively displaced in a horizontal direction to bifurcate a gas stream flowing through said bores of one of said adjacent layers into said bores of the other of said adjacent layers.

20. A grid according to claim 19, wherein said substantially vertical junctions are chamfered in horizontal cross-section to form mating interfaces between neighbouring furnace bricks in the same layer.