US3252261A

US3252261A - Grooved refractory brick construction

Info

Publication number: US3252261A
Application number: US326684A
Authority: US
Inventors: George R Rigby
Original assignee: Canadian Refractories Ltd
Current assignee: Canadian Refractories Ltd
Priority date: 1963-11-29
Filing date: 1963-11-29
Publication date: 1966-05-24
Anticipated expiration: 1983-05-24

Description

y 4, 1966 G. R. RIGBY 3,252,261

GROOVED REFRACTORY BRICK CONSTRUCTION Filed Nov. 29, 1963 2 Sheets-Sheet 1 FIG. 6

PATENT AGENT y 4, 1966 G. R. RIGBY 3,252,261

GROOVED REFRACTORY BRICK CONSTRUCTION Filed Nov. 29, 1965 2 Sheets-Sheet 2 PATENT AGENT United States Patent 3,252,261 GROOVED REFRACTORY BRICK CONSTRUCTION George R. Rigby, Lachute, Quebec, Canada, assignor to Canadian Refractories Limited, Montreal, Quebec, Canada Filed Nov. 29, 1963, Ser. No. 326,684 3 Claims. (Cl. 52573) This application is a continuation-in-part of United States application Serial No. 110,127, filed May 15, 1961, now abandoned. I

This invention relates to the construction of refractory brick used in furnace linings.

It is known in the art that the useful life of a refractory brick in a furnace lining is reduced by cracking due to the stresses which build up in brick as they are heated or cooled from one face. Ordinarily one face or end of a brick is subjected to much higher temperatures than the opposite face or end of the brick and a temperature gradient exists in the brick. With radical changes in temperature at the hot end, fluctuations in the gradient cause stresses which are frequently relieved by cracking the brick.

Careful investigation has shown that the magnitude of the stresses determines the degree to which the cracking occurs resulting in spalling with the loss of a portion of the brick.

When the end of a brick exposed in a furnace wall is subjected to the high furnace operating temperature, that end of the brick expands substantially while the opposite end remains for some time in its original condition. Thus heavy stresses are set up in the brick, particularly in its hot end. This results in spalling which substantially reduces the useful life of the brick in the furnace lining and increases the cost of operating the furnace. Similar conditions arise upon cooling.

The object of this invention is to provide a furnace wall structure wherein the tendency of the body of the brick in said wall to break away or spall in use is greatly reduced.

A further object is to provide a construction which will avoid cracking of the individual bricks in such a structure due to internal stresses built up during normal operation of the furnace.

In accordance with the invention, there is provided a furnace wall structure having a hot face confronting the interior of the furnace and a cold face in opposed relation to the hot face. The wall structure comprises a plurality of refractory bricks each having a pair of opposed plane side faces, a pair of opposed plane edge faces and a pair of opposed plane end faces. Theperpendicular distance between the end faces being the major dimension of the brick and the perpendicular distance between the side faces being the minor dimension of the brick. One of the end faces of each b-rick constitutes a portion of-the hot face and such hot end face is uninterrupted. Each brick has a series of grooves interrupting each face of at least one of the pairs of side and edge faces, such side and edge faces being otherwise uninterrupted. Each groove is defined by a pair of side Walls and has a width not substantially more than inch and a depth not substantially less than inch nor substantially more than inch. The medial plane between the side walls of each groove is at an angle of 0 to 45 to the plane of the hot end face. The walls of the groove closest to the hot end face are spaced therefrom a distance of about inch to 2 inches. Each of the interrupted plane faces has a fiat portion between the grooves of each adjacent pair of grooves, each such flat portion having a dimension of the order of one to one and one-half inches in a direction perpendiculatr to the end faces of the brick. The walls of the groove closest to the cold end face are at least 4 inches therefrom. The shortest distance between the bottom of any one of the grooves in one of the series and the bottom of any one of the grooves in the other series is not less than 70% of the perpendicular distance between the interrupted plane faces.

The structure of the brick will now be described with reference to the accompanying drawings in which,

FIGURE 1 is a perspective view of one form of the brick,

FIGURE 2 is a perspective view of another form;

FIGURE 3 is a cross-sectional view of a furnace structure embodying brick of the present invention,

FIGURE 3a is an enlarged perspective view of a portion of the furnace wall structure,

FIGURE 4 is a perspective view of another modified form of brick,

FIGURE 5 is a perspective view of a brick in accordance with the invention in a met-a1 casing, and

FIGURES 6 and 7 are diagrams illustrative of modifications which the structure of the brick may take.

In describing the brick construction the wide faces of the brick ,are referred to as the sides (A-FIGURE l), the narrow faces as the edges (B--FIGURE 1), and the smallest faces at the hot end (CFIGURE 1) and the cold end opposite said hot end. By hot end is meant that end of the brick which is adapted to be exposed to the interior of the furnace and by cold end the opposite end.

It has been found that the provision, as set forth, of grooves each not substantially more than @i preferably not more than Ma", in width extending not substantially less than into the body of the brick and the medial plane between the side walls thereof being at an angle of 0 to 45 to the plane of one end face of the brick greatly improves the spalling resistance of the brick. Optimum spalling resistance is obtained when the grooves extend into the brick not substantially more than The depth of the grooves as set forth applies to brick of any cross-sectional area except that in no case should the grooves reduce the cross sectional area of the body of the brick by more than 30%, since, as previously indicated, this would increase the tendency to crack. When the grooves extend into the brick substantially less than the stress set up by temperature fluctuations are not relieved sufiiciently to avoid cracking and spalling. Grooves which are located in planes which are not parallel to the end face of the brick must not be deeper than they would be when located in planes parallel to the end face.

The grooves are located from 4-2 inches from the hot face of the brick and from each other. The preferred spacing range is 1-1 /2 inches. The number of grooves depends upon the length of the brick, but it is not necessary to carry them closer than 4 inches from the cold end of the brick. At the outset of furnace operation, it is the groove or grooves nearest to the hot end which relieve stresses and prevent spalling. The grooves further removed from the hot end do not play an important part in relieving stresses until the brick is reduced in length through service.

Grooves located in the edge of the brick give better re sults than when located in the sides and are preferably located in planes parallel to the hot end and face of the brick.

It is not necessary to have the same number of grooves on opposite faces and the grooves in one face may be staggeredin relation to those in the other. Grooves, running longitudinally of the brick are not effective.

Grooves in the hot end face of the brick are not of value because they expose additional area in this face which is subject to slag attack.

The narrow grooves may be formed by cutting with a saw or by using a mould having internal projections of the required dimensions on its inner walls. In forming the narrow grooves by moulding, the projections on the mould are preferably V-shaped, about wide at the base and extending inwardly about When the narrow grooves are formed by cutting with a saw best results are obtained when the cuts are made before burning the brick.

FIGURE 1 shows a brick having five narrow grooves 1 in each edge of the brick running substantially parallel to its ends and extending inwardly about The grooves are spaced apart about 1" and the initial space or cut 1a is about 1" from the hot face of the brick. The grooves were formed by cutting before burning.

FIGURE 2 shows a brick having four narrow grooves 1 in each edge and two narrow grooves 2 in each of the sides A running substantially parallel to the edges of the brick. As shown, one groove 3 is located between the pair of grooves adjacent the hot end and one groove 2 is located between the pair of grooves 1 remote from the hot end.

FIGURE 3 is a diagrammatic view of a conventional form of furnace '10 having side walls 11 and roof 12. The interior or hot face of the furnace is indicated at 13. The walls 11 comprise a plurality of bricks 14 having grooves 1 therein in accordance with the invention. The roof 12 comprises a plurality of bricks 15 also having grooves 1 therein in accordance with the invention. FIGURE 3a illustrates more clearly the location of the grooves 1 and 2 with respect to the hot face 13. It will be apparent that, in the wall structure, the grooves 1 and 2 are not located in any exposed face of the brick but rather in a face adjoining another brick or other structural element.

It will also be appreciated that the brick of the present invention are laid as headers, i.e., a brick laid on fiat with its longitudinal dimension perpendicular to the face of the wall.

While the structure illustrated is of self-supporting nature, the brick of the present invention may be employed in externally supported walls and suspended arches.

The brick of FIGURE 4 illustrates the use of narrow grooves 4 in V-shaped form, as described above, and positioned in the same manner as grooves 1 in FIGURE 1.

FIGURE 5 shows a brick similar to that of FIGURE 1 having a U-shaped metal casing 5 with internal projections 6 which upon forming the brick by moulding produce spaces in the brick which are occupied by the projections. The inwardly projecting lugs 6 serve to anchor the casing to the brick in a well known manner. It will be apparent that the metal casing may be of other form and need only contact the two edges in which the grooves are formed or the brick may be wholly enclosed in metal.

FIGURE 6 diagrammatically shows the angular dis position of the grooves when they are located in the edges of the brick and are perpendicular to the sides of the brick. When the groove 7 is at 45 to the edge of the brick it occupies the plane D E F at angle X or D E H at angle Z. When angles X and Z become 90 the groove occupies the plane D E G which is shown in FIGURE 2.

Similarly FIGURE 7 shows the angular disposition of the grooves when they are located in and perpendicular to the sides of the brick. When the groove 8 is at 45 to the edge of the brick it occupies the plane I K L at angle Y or J KM at angle W.

Thus, it will be recognized that any of the described angular dispositions of the planes of the grooves or any combination thereof may be used in making the brick.

In determining the capacity of this brick structure to resist the disruptive influence of internal stresses developed therein during use in a furnace, the brick structure was subjected to what applicant defines as Wicket Spall 7 Test, as follows:

It consists of subjecting the end face of a brick alternately to (1) radiation from a furnace wall at 1100 C. and at a distance of 2 inches for 45 minutes, and (2) a blast of air at room temperature for 15 minutes. The cycle is repeated until either the end of the brick breaks off or it remains whole after 10 cycles, when it is assessed visually as to the severity of the damage incurred in the test. Ten cycles is the normal duration of the test, since it has been found that this represents adequate spalling resistance for most service conditions. Brick made of magnesia materials under this test have, on the aver-age, spalled at 1 to 3 cycles. Brick made of chrome ore spall in the same range, whereas brick made from chrome ore and 20-30% magnesia spalled at 3 to 4 cycles.

Brick of the construction herein described and shown and made of these types of materials, having a plurality of narrow grooves arranged asdescribed and shown have remained intact after an excess of 10 cycles. Brick of the structure shown in FIGURES l and 4 have been found to resist spalling after as many as 30 cycles although after 14 cycles there was evidence of small cracks in some cases. The brick structure of FIGURE 2, having the grooves in the sides as well as in the edges, withstood 30 cycles.

To further illustrate the effect of angular disposition of the grooves, as described with reference to FIGURES 6 and 7 the following table is included, showing the variety of angles at which the grooves may be disposed in relation to the respective faces of the brick and the result of the Wicket Spall Test described. For satisfactory spalling resistance figures 10 is a minimum. The signs are an indication of the relative merits of those tests that have not spalled in 10 cycles with indicating brick likely to go 30 or more cycles.

Spalling results on brick with grooves at various angles Angle of Angle of Test Groove Spall Data Groove Spall Data (Angle X (Angle Y Figure 6) Figure 7) 1 No grooves.

The orientation of a groove can best be described by reference to the medial plane which is the plane midway between the two planes in which the major walls of the groove lie.

In the accompanying claims, the expression wall structure includes the roof structure as well as the side walls of the furnace.

I claim:

1. A furnace comprising a wall structure having a hot face confronting the interior of said furnace and a cold face in opposed relation to said hot face, said wall structure comprising a plurality of refractory bricks each having a pair of opposed plane side faces, a pair of opposed plane edge faces, and a pair of opposed plane end faces, the perpendicular distance between said end faces being the major dimension of said brick and the perpendicular distance between said side faces being the minor dimension of said brick, each said brick having a first one of said end faces exposed to the interior of said furnace and constituting a portion of said hot face and a second one of said end faces constituting a portion of said cold face, said first end face being uninterrupted, each said brick having a series of grooves interrupting each said plane face of at least one of said pairs of side and edge faces, said side and edge faces being otherwise uninterrupted, a pair of side walls defining each said groove, each said groove having a width not substantially more than inch and a depth not substantially less than inch nor substantially more than inch, the medial plane between said side walls of each said groove being at an angle of 0 to 45 to the plane of said first end face,

said walls of the one of said grooves closest to said first end face being spaced from said first end face a distance of about inch to 2 inches, each said interrupted plane face having a flat portion extending between said grooves of each adjacent pair of said grooves, each said flat portion having a dimension of the order of one to one and onehalf inches in a direction perpendicular to said end 'faces, said walls of the one of said grooves closest to said second end face being at least 4 inches therefrom, and the shortest distance between the bottom of any one of said grooves in one of said series and the bottom of any one of said grooves in the other one of said series being not less than 70% of the perpendicular distance between said interrupted plane faces.

2. A furnace Wall structure as defined in claim 1 wherein each said groove is V-shaped in cross-section.

3. A furnace wall structure as defined in claim 1 wherein a series of said grooves is provided in each of said side and edge faces.

References Cited by the Examiner UNITED STATES PATENTS FRANK L. ABBOTT, Primary Examiner.

HENRY C. SUTHERLAND, Examiner.

D. R. COMUZZIE, Assistant Examiner.

Claims

1. A FURNACE COMPRISING A WALL STRUCTURE HAVING A HOT FACE CONFRONTING THE INTERIOR OF SAID FURNACE AND A COLD FACE IN OPPOSED RELATION TO SAID HOT FACE, SAID WALL STRUCTURE COMPRISING A PLURALITY OF REFRACTORY BRICKS EACH HAVING A PAIR OF OPPOSED PLANE SIDE FACES, A PAIR OF OPPOSED PLANE EDGES FACES, AND A PAIR OF OPPOSED PLANE END FACES, THE PERPENDICULAR DISTANCE BETWEEN SAID END FACES BEING THE MAJOR DIMENSION OF SAID BRICK AND THE PERPENDICULAR DISTANCE BETWEEN SAID SIDE FACES BEING THE MINOR DIMENSION OF SAID BRICK, EACH SAID BRICK HAVING A FIRST ONE OF SAID END FACES EXPOSED TO THE INTERIOR OF SAID FURNACE AND CONSTITUTING A PORTION OF SAID HOT FACE AND A SECOND ONE OF SAID END FACES CONSTITUTING A PORTION OF SAID COLD FACE, SAID FIRST END FACE BEING UNINTERRUPTED, EACH SAID BRICK HAVING A SERIES OF GROOVES INTERRUPTED, EACH SAID PLANE FACE OF AT LEAST ONE OF SID PAIRS OF SIDE AND EDGE FACES, SAID SIDE AND EDGE FACES BEING OTHERWISE UNINTERRUPTED, A PAIR OF SIDE WALLS DEFINING EACH SAID GROOVE, EACH SAID GROOVE HAVING A WIDTH NOT SUBSTANTIALLY MORE THAN 5/16 INCH AND A DEPTH NOT SUBSTANTIALLY LESS THAN 11/32 INCH NOR SUBSTANTIALLY MORE THAN 17/32 INCH, THE MEDIAL PLANE BETWEEN SAID SIDE WALLS OF EACH SAID GROOVE BEING AT AN ANGLE OF 0* TO 45* TO THE PLANE OF SAID FIRST END FACE, SAID WALLS OF THE ONE OF SAID GROOVES CLOSEST TO SAID FIRST END FACE BEING SPACED FROM SAID FIRST END FACE A DISTANCE OF ABOUT 3/4 INCH TO 2 INCHES, EACH SAID INTERRUPTED PLANE FACE HAVING A FLAT PORTION EXTENDING BETWEEN SAID GROOVES OF EACH ADJACENT PAIR OF SAID GROOVES, EACH SAID FLAT PORTION HAVING A DIMENSION OF THE ORDER OF ONE TO ONE AND ONEHALF INCHES IN A DIRECTION PERPENDICULAR TO SAID END FACES, SAID WALLS OF THE ONE OF SAID GROOVES CLOSEST TO SAID SECOND END FACE BEING AT LEAST 4 INCHES THEREFROM, AND THE SHORTEST DISTANCE BETWEEN THE BOTTOM OF ANY ONE OF SAID GROOVES IN ONE OF SAID SERIES AND THE BOTTOM OF ANY ONE OF SAID GROOVES IN THE OTHER ONE OF SAID SERIES BEING NOT LESS THAN 70% OF THE PERPENDICULAR DISTANCE BETWEEN SAID INTERRUPTED PLANE FACES.