US2243339A - Refractory wall construction - Google Patents

Description

May 27, 1941. HENZEL ETAL 2,243,339

REFRACTORY WALL CONSTRUCTION Filed June 10. 1959 2 Sheets-Sheet 1 IN VENTORS .TOHN H- HENZEL EDMUND 7T HEINRICH XTTORNEYS v Patented May 27, 1941 OFFICE,

REFRACTORY WALL CONSTRUCTION John H. Henzel and Edmund-'1. Heinrich, i

Cleveland, Ohio Application June 10, 1939, Serial No. 278,511

13 Claims.

This invention relates to wall structures and more particularly to an improved refracto y and/or insulating wall especially adapted for use in fuel burning furnaces or the like.

In the building of walls which will withstandthe high temperatures encountered in modern furnace practice numerousattempts have been made to provide for the expansion and contraction which necessarily occurs in the wall structure during furnace operation. Bricks of refractory material have been supported on various crating at temperatures which would otherwise necessitate special heat resisting alloy; the provision of a. wall structure having a refractory intypes of metallic wall members. In numerous cases these bricks have been of special form with resulting greatly increased expense'over the cost of standard rectangular 'bricks. Furthermore, the metal supports for the refractory material have previously been partly embedded in the useful or main portion of the refractory thereby pot only shortening the life or period of usefulness of the refractory, due to decreased thickness of refractory between its hot face and its metal support, but also necessitating the use of special alloy metal to resist and withstand the high temperatures due to the proximity of the metal sup.- port to the hot face of the refractory. Another important consideration is the heat loss factor, which increases in direct ratio to the temperature of the metal supporting the refractory as, regardless of design, the metal serves to drain the heat from the refractory and any reduction in temperature of the refractory supporting system or any part thereof increases the efficiency of the wall from a thermal storage viewpoint. It is also frequently desirable to build into the wall structure insulating material in order to retain and prevent waste of heat by radiation from the furnace walls. In order properly to retain the insulating material in position wires or other special fastening means have been employed.

It is among the objects of our present invenner surface supported by simple and effective means, which supporting means may also locate and hold in position insulating material; the provision of a refractory wall in which expansion and-contraction of the refractory material does not exert forces which are carried into the furnace shell or casing, thus permitting the use of an'extremely light casing with resulting saving in weight,'material and installation; the provision of a wall structure which makes possible the utilization of a relatively large percentage of the refractory material as refractory, rather than merely reinforcement of refractory to make possible its suspension from metal arms or supporting members; the provision of a wall structure which makes efllcient use of dead or non-circulating air, confined in relatively small cells, to take the place of costly special shaped refractory previously used; and the provision of an insulating refractory wall which is simple and economical to install and maintain, which is very tion to provide a refractory wall structure the supporting elements of which may be largely fabricated in the shop and easily installed by relatively unskilled workmen on the job and which is adapted to employ a large percentage of standard minimum cost 9" refractory bricks with a relatively small number of one other type brick which is essentially a standard large brick with a slot of very simple form and which may be made by slotting a standard large brick, on the job if desired. Other objects of our invention are the provision of refractory wall supporting means having hangers which are subjected to so little of the heat from the furnace that they may be made of cast iron for application to furnaces opefficient and which provides a minimum metal path from the inner portion of the wall to the outer portion thereof thus substantiallyreducing the heat loss therethrough.

The above and other objects of our invention will appear from the following description of several embodiments thereof, reference being had to the accompanying drawings, in which Figure l is a fragmentary perspective view of a refractory wall embodying one form of our invention.

Figure 2 is a fragmentary perspective view of a corner arrangement of the same type of wall as shown in Figure 1.

Figure 3 is a plan view of one of the refractory brick and insulation supporting brackets employed in the wall structure of Figures 1 and 2.

Figure 4 is an end elevation of the bracket shown in Figure 3.

Figure 5 is a perspective view generally similar to Figure 1 but illustrating a slightly modified form of our wall structure.

Figure 6 is a view of the refractory supporting bracket used inthe wall of Figure .5.

Figure '7 is an end elevation of the bracket shown in Figure 6.

Referring particularly to Figure 1, our improved wall structure, in a preferred form, includes a plurality of spaced vertically extending brick-stays or columns I.

The shell or casing 1 units, generally indicated at C, are arranged in superimposed relation extending between the vertical columns I. These units C comprise casing plates 2, which are riveted or otherwise suitably secured to the columns I, and which have.

abutting flanged horizontal edges 3 which are bolted or riveted together, as seen at 4. Inwardly projecting vertical ribs 5 are secured to the plates 2, preferably by welding, and are provided with spaced holes 5. These holes lie in horizontal rows and accommodate the bolts 1 which fasten the brackets B to the ribs 5 and which in turn support the load carrying courses of refractory bricks I8 and the sheets of insulating material 8. The ribs 5 stiffen the plates 2 and make possible the use of light weight casing members without sacrifice of strength.

As is clearly seen in Figures 1, 3 and 4, the brackets B each have a vertical flange 9 through which a bolt I extends, clamping the bracket against the side of a rib 5. The brackets are preferably castings and, as will be later explained, may be made of ordinary cast iron. The rib or flange 9 connects to the vertical back portion III which has angularly extending brick engaging flanges II and I2. The base portion I 3 is connected to both the flanges I I and I2 and the back I and has outwardly projecting legs I4 and I5 which carry the vertically extending insulation retaining flanges I6 and I1.

The insulation 8 is made in panels of suitable material which are equal in width to the distance between adjacent vertical ribs 5, of a height equal to the distance between the base portions I3 of adjacent vertically spaced brackets B, and a thickness equal substantially to the distance between the outer face of the back III and the inner face of the flanges I6 and I I of the brackets B. Each of these insulating panels 8 is supported and held in position by engagement, at each of its corners, with one of the brackets B. 'As the flanges I6 and H are spaced from the plates 2, when the panels of insulation are placed in position, an air space is formed between the inner surface of the plates 2 and the outer surface of the insulating panels 8. It will be seen that, as these air spaces are continuous and free from obstructions from furnace foundation to roof or arch, they may be utilized as natural stacks to induce vertical air currents between casing and insulation to cool the insulation and therelv insure a low casing temperature with comparative absence of temperature stresses. In other cases it may be desirable that these spaces be used as ducts to convey air from a fan or blower to the furnace for combustion air requirements, thereby gain ing all the advantages of a low casing temperature plus the increased furnace eillciency to be gained by the use of preheated air for combustion. In still other instances the spaces may be sealed top and bottom with dividers or headers at intermediate points thereby confining the air to form dead air spaces as additional insulation. The fan connections and the dividers or headers just referred to are not shown in the accompanying drawings but may be of any suitable type.

As noted above, the brackets B are secured to the ribs 5 by means of bolts I which extend through the holes 6. This results in the brackets being arranged in vertically spaced horizontal rows.

Each row of brackets B supports one of the load carrying courses of refractory bricks I8. These bricks are preferably standard 9" large brick (9" x 6%" x 2 with the center to center distance between adjacent ribs 5 being approximately equal to twice the length of one of the bricks. All of the supporting courses of bricks I8 are identical and each brick I8 is provided with a slot or groove I9, located adjacent one end and which may conveniently be sawed into the refractory brick after it is made. These slots I9, as illustrated, are preferably cut at an angle to the ends of the bricks and fit-over the angle webs II and I2 of the brackets B. A preferred design of bracket B, as illustrated in Figures 3, 4, 6 and 7, is one in which the longitudinal dimension of the horizontally extending base I 3 a is such that the base will extend to or past the center of each supported brick in the lengthwise direction, thereby restricting the tendency of the bricks to rotate about their axes. The unslotted or free end surface 20 of each of the bricks I8 abuts the. corresponding free end of the adjacent brick I8 while the slotted end of each brick I8 abuts the slotted end of the next adjacent brick which is supported by the same bracket B. Of course, suitable cement or plaster is used between the brick ends. Due to this abutting relation of the ends of the bricks I8, and due to the engagement of the flanges or webs' II and I! of the brackets B with the slots in the bricks I8, and

' because of the engagement of a portion of the vertical outeredge of each brick I8 with the vertical back III of the brackets B, the bricks of each load supporting course are firmly supported and prevented from collapse although they may expand or contract in any direction without imposing serious strains on either the bricks or the supporting wall structure.

As shown in Figure 1, each course of load carrying bricks I8 supports three courses of relatively narrow wall bricks 2|. These three courses of wall bricks 2I are laid in the usual overlapping fashion. on top of each load carrying course of bricks I8 and the inner faces of all of the bricks are aligned to provide a plane refractory surface. Cement is used between the brick surfaces in the usual manner. Although the supported wall bricks 2| substantially fill the space between the load carrying courses of the wall, each section of the wall, comprising a load carrying course and three supported courses laid on top thereof, constitutes an independent self supporting unit and may be removed or replaced without effecting the rest of the wall structure. In some cases where strength is not such an important consideration the load carrying courses may be spaced vertically at greater intervals. Actual tests have shown that one load carrying course, without any support below, will successfully carry as many as 25 to 30 courses of supporting bricks. In the walls shown in Figures 1 and 5 only 25% of the total number of bricks making up the wall engage and are supported by the bracket members. Of course, if more than three courses of intermediate or wall bricks 2| are carried by each load carrying course the percentage of bricks which are supported by brackets will be further reduced. For example, if nine courses of bricks 2| were supported by a single course of load carrying bricks I8 only 10% of the total number of bricks in the wall would be other than standard 9" bricks laid up in the usual fashion. Even if only two courses of standard bricks are carried by each load carrying course still only one-third of the total number of bricks are in contact with the supporting bricks.

Inspection of Figure 1 will show that additional air spaces are created between the outer edges of the bricks 2| and the inner surfaces of the insulating panels 8. These air spaces are dead and run horizontally of the wall structure but extend vertically only between two' adjacent courses of load carrying bricks I! as these had carrying bricks extend to and substantially engage the surfaces of the insulating panels 8. It will also be noted that a large portion, on the -order of one-third the total horizontal surfaces,

of the supporting or load carrying bricks l8 and a large percentage of the highest temperature portions of the brackets B are exposed to the air in these spaces or cells. Considering this in connection with the law of physics which states that the volume of heat transferred through a medium or from one medium to another is a function of the difference in temperature, the greater the diiference the greater the volume of heat transferred, it will be seen that a considerable volume of heat will be transferred from the bricks l8 and brackets B to the air within the cells by a combination of radiation and convection. While the temperature of the air within the cells is raised by this action the difference in thetemperature within the cells is, compared to atmospheric'temperature, too slight to cause an appreciable loss of heat through the insulation panels 8 to atmosphere. The increase of the temperature of the air within the cells lowers the temperature diflerential between the hot and cold faces of the bricks 2| thereby reducing the heat transfer or loss through the portion of the wall formed by the bricks 2|; and the heat lost from the brackets B to the air within the cells lowers the temperature differential between the hot and cold ends of the brackets thereby reducing what might otherwise be a considerable heat loss due to conduction through the insulation 8 by means of the metal of the brackets B. The creation of these dead air spaces therefore greatly increases the efliciency of the wall structure and effectively prevents heat losses in undesirable quantities.

Another of the important features of our invention is achieved by the small size of the bracket members B and the small area of contact between these brackets and the load supporting courses of the refractory brick structure. By reducing the area of contact between the brick and metal parts of the wall the transfer of heat from the bricks to the casing is further reduced. As a metal path forms an excellent means for conducting heat to the outer surface of the wall from whence it may be lost to the atmosphere, it is evident that our wall structure, which uses a relatively small number of brackets engaging with small contact area only a relatively few of the bricks which make up the wall, results in reducing to a minimum the heat loss by conduction through metal paths. All of our metal castings B are so protected from the heat of the furnace, due to the fact that the intermediate or wall bricks 2| stop short of the inner edges of the brackets B and due to the small contact between the brackets and the load carrying bricks l8, that we have found that we are able successfully to use cast iron brackets for furnace temperatures which in all types of prior structures of this type with which we are familiar have necessitated expensive heat resisting alloy or the members in direct contact with the bricks.

Cast iron has a safe working temperature of approximately 650 F. and when this temperature is exceded cast iron disintegrates due to excessive grain growth and may permit the entire wall structure to collapse. with our furnace wall structure we have found that the ture at the outermost portions of the brackets B does not exceed 450 F. even in high temperature furnaces where the temperature adjacent the inner face of the refractory bricks may be as high as 1850 F.

The wall illustrated in Figures 1 and 2 includes a supporting bracket 22, havinga flange 23 extending through the brick work to a suitable web 24 to which it is bolted or otherwise secured. The web 24, as illustrated, is secured to the vertical stud or column I. Tubes 25, for oil cracking or other purposes, are supported in the tion 8 in Figure notches in the brackets 22 and it will be understood that in other types of wall structures these tubes and their supporting brackets may be supported by other means or entirely omitted. The arrangement of refractory bricks and theirsupports is, of course, equally well adapted for use in various other kinds of furnaces such as arr-- nealing, baking, normalizing, etc.

, In Figure 2 we have illustrated a corner construction embodying the features of the wall structure shown in Figure 1. Each of the adjoining walls D and E are built up as illustrated in Figure 1. Where the walls meet, the bricks IQ of each load carrying course overlap. This is made possible by locating each horizontal row of brackets B of the wall D above the corresponding rows of brackets B of the wall E a distance equal to the thickness of a single brick. The casing members 0 of the adjoining walls extend to and are supported by the columns 26 and 21. By means of the staggered or offset location of the load supporting courses and the generally indicated at F and which is shown in enlarged detail in Figures 6 and '7. These brackets F each have a vertical web 28 provided with spaced holes 29 and 30 which accommodate bolts Si by which the brackets are secured to the webs 5. These webs are somewhat narrower than the webs 5 of Figure 1 and, as the brackets F are not provided with outwardly extending portions H or l5 or with the insulation retaining flanges l6 and ll of the brackets B, the insula- 5 is disposed between the casing sheets 2 and the outer surfaces of the back portions 32 of the brackets F. In the wall of Figure 5 no air space is provided between the casing sheets 2 and the insulating panels 8. The load carrying bricks l8 engage and are supported by the angular flanges 33 and 34 and rest upon the base 35 of the brackets F in the same manner as illustrated in Figure 1. v

The same construction as is shown in Figure 5 may be used with the omission of,.the insulation 8 where heat'losses are of no consequence, or the space occupied by the insulation can be utilized to provide air ducts to preheat air for combustion where it is desirable to obtain a greater preheat temperature than is possible with an insulated wall.

The intermediate, supported bricks 2| in Figure 5 are spaced from the insulation 8 a distance equal to the depth of the base portion 35 of. the

brackets F and thus it will be observed that the temperawall of Figure 'fi permits a most eflicient use of the standard rectangular refractory bricks in the same manner as the structure of Figure 1. A minimum .of brick surface is in contact with the metal supports. The size and weight of l the metal supports is reduced to a practical minimum and, by ample protection of the brackets B and F from the heat of the furnace, plus sufficient heat drainage from the brackets, their failure due to excessive heat is completely eliminated even though the brackets B and F are made of ordinary cast iron.

In our improved wall structure only one relatively small and light weight type of brick supporting bracket is employed. These brackets may be used interchangeably and if a furnace is dismantled the old brackets may be used without alteration in another furnace. Our construction permits the prefabrication of the casing sheets 2 with the ribs 5 drilled and attached to locate properly the brick supporting brackets B or F. It is only necessary for the erector on the job to mount the panels 2 on suitable vertical supports, attach the brackets B or F by bolting them to the ribs 5, and then start building up the brick structure, with or without the insulating panels 8 as may be desired. If itis necessary to repair or replace any part of the wall structure the intermediate supported wall bricks 2| can be removed between any two adjacent load carrying courses of bricks it without disturbing the rest of the structure as each load carrying course carries only its own courses of standard bricks. Corners can readily be constructed because the bricks of the load carrying courses of one wall have cantilever supports on their brackets and extend out into overlapping relation with the bricks of the corresponding load carrying courses of the other wall.

Although we have described the illustrated embodiments of our invention in considerable detail it will be understood by those skilled in the art that variations and modifications may be made without departing from the scope of our invention and we do not, therefore, wish to be limited to the particular arrangements herein shown and described, but claim as our invention all embodiments thereof coming within the scope of the appended claims.

We claim:

1. In a wall structure of the type described, the combination of a casing having a plurality of spaced vertical ribs extending inwardly therefrom, a plurality of brick supporting brackets secured to said ribs and arranged in vertically spaced horizontal rows, courses of load supporting bricks supported by each of said rows of brackets, and intermediate courses of bricks, narrower than said load supporting bricks, substantially filling the spaces between said load supporting courses.

2. In a wall structure of the type described, the combination of a casing, a plurality of inwardly projecting vertically extending rib members secured to said casing, brick supporting brackets secured to said ribs and arranged in a horizontal row, a course of bricks supported by said row of brackets, each bracket of the row being adapted to support, in abutting relation, the ends of two adjacent load carrying bricks the opposite free ends of which engage the free ends of other load carrying bricks similarly supported by adjacent brackets, and a course of supported bricks carried by said course of load carrying bricks.

- and each bracket supporting brackets, each of 3. In a wall structure of the type described, a plurality of brick supporting brackets, means for supporting said brackets in a horizontal row, a course of load carrying bricks supported by said brackets, each of said bricks being supported at one end by a bracket and engaging an adjacent brick at its other or free end, the length of said bricks being equal to approximately one-half the horizontal center to center distance between brackets and each bracket supporting the ends of two bricks. 4

4. In a wall structure of the type described, a plurality of brick supporting brackets, means for supporting said brackets in a horizontal row, a course of load carrying bricks supported by said said bricks being supported at one end by a bracket and engaging an adjacent brick at its other or free end, the length of said bricks being equal to approximately one-half the horizontal center to center distance between brackets and each bracket supporting the ends of two bricks, said brackets having brick engaging flanges and brick supporting bases and said bricks being slotted to fit said flanges.

5. In a wall of the type described, a plurality of brick supporting brackets, means for supporting said brackets in a horizontal row, a course of load carrying bricks supported by said brackets, each of said bricks being supported at one end by a bracket and engaging an adjacent brick at its other end, the length of said bricks being equal to approximately one-half the horizontal center to center distance between brackets the ends of two bricks, and a course of supporting bricks, narrouer than said load carrying bricks, disposed on said course of load carrying bricks with their inner faces aligned with the inner faces of said load carrying bricks.

6. In a wall of the type described, a casing, a plurality of brick supporting brackets secured to said casing, a plurality of load supporting bricks, each of said load supporting bricks being supported on a bracket, said load supporting bricks being arranged in vertically spaced horizontal courses with the bricks of each course in end to end abutting relation, courses of wall bricks substantially filling the spaces between said courses of load supporting bricks, said wall bricks being narrower than said load supporting bricks, and panels of heat insulating material supported by said brackets and disposed between the outer surfaces of said load carrying bricks and said casing.

7. A brick supporting bracket for wall structures comprising a vertical flange portion adapted to be secured to a supporting member, a base portion attached to said flange and disposed horizontally, a back portion extending substantially at right angles to said flange and base portions, and a pair of spaced brick engaging flanges extending vertically upwardly from said base portion and arranged one on each side of said vertical flange portion.

8. A brick supporting bracket for wall structures comprising a. vertical flange portion adapted to be secured to a supporting member, a base portion attached to said flange and disposed horizontally, a back portion extending substantially at right angles to said flange and base portions, and a pair of brick engaging flanges extending vertically upwardly from said base portion and angularly disposed relative to the plane of said brick portion at the same but opposite angle-E whereby said brick engaging flanges diverge away from said back portion.

9. A brick supporting bracket for wall structures comprising a vertical flange portion adapted to be secured to a supporting member, a base portion attached to said flange and disposed horizontally, a back portion extending substantially at right angles to said flange and base portions, a pair of brick engaging flanges extending vertically upwardly from said base portion, and leg portions extending from said base portion adjacent each end thereof, said leg portions having insulation retaining means at their ends.

10. A brick supporting bracket for wall structures comprising a vertical flange portion adapted to be secured to a supporting member, a base portion attached to said flange and disposed horizontally, a back portion extending substantially at right angles to said flange and base portions, a pair of brick engaging flanges extending vertically upwardly from said base portion and angularly disposed relative to the plane of said back portion at the same but opposite angles whereby said brick engaging flanges diverge away from said back portion, and leg portions extending from said base portion adjacent each end thereof, said leg portions having insulation retaining means at their ends.

11. A brick supporting bracket for wall structures comprising a flange portion adapted to be secured to a supporting member, a base portion attached to said flange and disposed horizontally, a back portion extending substantially at right angles to said flange and base portions, and brick-holding means adapted to engage and hold bricks in end to end relation on said base portion.

12. A brick supporting bracket for wall structures comprising a flange portion adapted to be secured to a supporting member, a base portion attached to said flange and disposed horizontally, a back portion extending substantially at right angles to said flanges and base portion, and brick-holding means adapted to engage and hold a brick on said base portion against movement longitudinally or transversely thereof.

13. In a wall of the type described, a plurality of brick supporting brackets, means for supporting said brackets in spaced relation in horizontal rows, each of said brackets including a base portion having a substantially horizontally extending brick supporting surface and brick-holding means adapted to engage and hold a brick on said base against substantial movement longitudinally or transversely thereof, a plurality of load supporting bricks, each of said load supporting bricks having smooth top and bottom surfaces and being supported on a bracket and held in position by said maintaining means, said load supporting bricks being arranged in vertically spaced horizontal courses, and courses of wall bricks substantially filling the spaces between said courses of load supporting bricks.

JOHN H. HENZEL. EDMUND T. HEINRICH.

Images