CA1039947B - Furnace lining module - Google Patents

Abstract

ABSTRACT OF THE DISCLOSURE
A protective lining block suitable for attachment to the inside of a boundary wall of a furnace chamber, said block being generally rectangular in shape and having a boundary wall side and an opposite furnace side, and a mat composed of high-temperature-resisting thermally insulating fibers arranged to extend generally in a direction perpendicular to and joining said boundary wall side and said opposite furnace side.

Description

. 1039947 The present invention relates to apparatus for insulating the interior of a high temperature furnace ~.
and more particularly to a ceramic fiber mat constituting the hot face of the insulation and wherein substantially all of the fibers in the fiber mat lie in planes which -are generally perpendicular to the various walls of the ~
furnace. .
The problems involved in protecting and insulating `-~`
the walls and ceiling of a high temperature furnace are well known. Historically, the interiors of high tempera~
ture furnaces have been lined with various types of bricks .

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capable of withstanding these high temperatures. When the brick lining wears out, however, it is an arduous and time~
consuming task to replace the old brick with a new brick lining. On the other handj efforts have been made to in-sulate the interior of a furnace where the interior or hot ~
- face of the insulation includes or consists of ceramic ~`
fiber material. Ceramic fiber material, as referred to ~
herein, is generally available in the form of a ceramic ;
fiber blanket which is customarily manufactured in a manner `~
similar to the conventional paper-making process. As such, the fibers which constitute the blanket, (as is also the -case in connection with paper) are oriented in planes which -are generally parallel to the longitudinal direction of `~
formation of the blanket or sheet. When, as proposed in the past, lengths of ceramic fiber blanket are placed against ;
a furnace wall or overlying an intermediate insulating ~`
member which, in turn, would be attached to the furnace wall, the fibers will then be lying in planes generally ~ ~
parallel to the furnace wall. Also, it is believed that a ~- ;
majority of these fibers will be lying in a direction "
which would tend to be colinear with the direction of formatlon of the blanket itself, although a considerable - `
number of fibers are still in a more or less random dispo- -. ~ . .
sition in these planes. Nevertheless, where the fibers are disposed in planes which are parallel to the furnace wall, ;
there is a tendency for the fiber blanket material to -produce cracks which result from heat shrinkage.
With certain types of insulation it is recognized that high temperature problems sometimes involve melting, ,~
30~ oxidation and other types of deterioration of the insula-ting medium. As far as ceramic fiber insulation is con-cerned, the high temperature problems are generally cracking, ., .
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d~lamination (peeling off of the surface layers), and devitri-fication, all of which are believed to be interrelated. ~t the lower temperatures of the recommended range of the present invention, namel~, 1600 to 2800F, devitrification will take ~ -place relatively slowly, whereas at the higher end of the range, devitrification will take place quite rapidly, followed, in short order, by cracking and/or delamination.
In retrospect, the prior art broadly discloses the feature of reorienting fiber insulation, but only in connection with low temperature insulation. For example, United States Patent No. 2,949,953 issued August 23, 1960 to Di Maio et al and United States Patent No. 3,012,923 issued December 12, 1961 to Slayter, both show the cutting of strips of fibrous material from a sheet or mat of the same, arranging the strips in a side-by-side relation to provide an end fiber exposure, com-pressing the strips and while still compressed, applying an adhesive backing sheet of paper or cloth to one side edge only of the resulting compressed block; therea~ter when the orces of compression are removed the resulting block will tend to curl around the adhesive sheet so as to form a suitable insulating body for pipe or the like. However, the resulting insulation is necessarily low-temperature insulation because the pipe is in direct contact with the heating or cooling medium which it carries; the insulation is used on the external surface of the body or pipe to be insulated; the sole purpose in arranging the strips in an end or edgewise exposure of the fibers is to permit compression of the strips so that, after one side edge is secured in place by means of the backing strip, advantage can be taken of the relatively greater expansibility along the unsecured edge.

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SUMMARY OF THE IN~ENTION ;~
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The present invention comprises an insulation module for lining the interior walls of a furnace, comprising a rigid block of refractory material having two opposed flat sides, ~ -one side being the cold face for attachment to the furnace wall and the other side being the hot face for exposure to the furnace heat, a resilient fiber insulation mat forming at least the hot - -face and being held flat within the rigid block prior to instal~
lation on the furnace wall, the fibers in the insulation mat being generally randomly oriented in planes, such planes being ~
substantially perpendicular to the hot face. ~-The ceramic fiber mat is preferably made up of strips which are cut tr~nsversely from a length of ceramic fiber blank- ;`
eting which is commercially available. The strips are cut from ``
the fiber blanket in widths that represent the linear distance from the cold face to the hot face of the insulating fiber mat.
The strips which are cut from the blanket are placed on edge and laid lengthwise ad~acen~ each other wLth a sufficient number of strips being employed to provide a mat o~ desired width.
Naturally, the thicXness of the fiber blanket from which the ~
strips are cut will determine the number of strips required to -construct the mat. The strips can be fastened together by ` `
wires, or by ceramic cement o~ mortar which is preferably employed in the region of the cold face of the mat. The mat - can be applied to the furnace wall or to an intermediate member, by means of a stud welding method or by ceramic cement, mortar, ` `
or the like.
In a more limited aspect the present invention comprises an insulation module for lining the walls of a high temperature furnace and being preassembled prior to installation, -`-comprising: - -a relatively rigid block of refractory material-4-~ 03994'^~
having a ~lat side for attachment to the furnace wall as thecold face, said block having substantially centrally located opening extending at right angles to the cold face; ` `~-a washer disposed on the surface of said block remote from said hot face and having a hole therein aligned with the opening in said block;
a metallic stud extending through said hole in said washer and through said opening in said block;
a threaded nut threadedly engaging the other end of said stud and overlying said washer;
a plurality of strips of ceramic fiber blanket dis-posed in parallel side-by-side arrangement over the surface of said block remote from said cold face and forming a ceramic fiber mat completely covering the face of said block, the fibers in said mat being generally randomly oriented in planes, the planes being generally perpendicular to the cold face of said block, ~aid mat also including strips of ceramic fiber at the side edges thereof extending downwardly to said cold face to cover the edges of said block.
For the purposes of the following description, "high temperature" will mean temperatures in excess of 1600F i~
and, preferably, in the range of 1600F to 2800F. The ceramic fiber strips referred to herein are cut from a ceramic fiber blanket which is commerciall~ availabla from several different manufacturers; these blankets are available as l'Kaowool" (a trademark of Babcock ~ Wilcox), 'IFibre-Frax'' (a trademark of Carborundum Co.), "Lo-Con" (a trademark of Carborundum Co.~, :: .
and "Cero-Felt" (a trademark of Johns Manville Corp.). Most of these ceramic fiber blankets have an indicated maximum ;~
operatinq temperature of àbout 2300F. The end or edge fiber exposure provided by the present invention not only provides an improved insulation up to the maximum indicated operating `

iO39947 : ~
temperatures suygested by the manufacterers, but because devi~
trification and its deleterious effects are largely eliminated, ~.
also permits operation up to about 2800F. : .
By arranging the fibers in an end or edgewiss `-. -exposure; that is, where the fibers are oriented in planes gen-erally perpendicular to the wall of the furnace, devitrification is not ~ecessarily avoided but its undesirable side effects are minimized or eliminated because de~itrification takes place at `
the ends of the fibers rather than along the lengths thereof; `.` :
thus cracking and delamination are essentially avoided by the .
present invention even up to a temperature of 2800F which is `
above the recommended maximum temperature specifications imposed upon the fiber blankets by the manufacturers. .
Brief Description of the Drawings -;;
Figure 1 is a fragmentary plan view of an .
insulating mat made from strips of a ceramic fiber blanket;
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1(~39947 Figure 2 is a fragmentary ,side elevation of the ceramic fiber mat shown in Figure l;
Figure 3 is an end elevation of the ceramic fiber mat shown in Figure l;
Figure 4 is a plan view of another embodiment of a - -ceramic fiber mat made in accordance with the present invention;
Figure 5 is a side elevation of the ceramic fiber ~ -mat shown in Figure 4 with certain internal connecting members shown in dotted lines and further showing -the association of the resulting insulating member with a furnace wall; :
Figure 6 is an end elevation of the ceramic fiber ~:
mat shown in Figure 5;
Figure 7 is a view similar to Figure 6 showing a method of stud welding of the resulting insulating member to a furnace wall;
Figure 8 is an enlarged and fragmentary detail view, with certain parts in cross-section, of the stud, nut and associated structure involved;
Figure 9 is a view similar to the lower portion of Figure 8 showing the relationship of the various parts ... , ~ ~
following the welding operation; -Figure 10 is an enlargement, on a slightly larger scale, of the retaining ring shown in Figure ~;
Figure 11 shows a parquet-type arrangement of insulating members on a furnace wall;
Figure 12 shows an enlargement of insulating members on a furnace wall with spaces between adjacent members being ~illed with separate insulating elements;

1039947 `;~
Figure 13 shows one embodiment of a separate insulating element to be inserted between adjacent insulating members;
Figure 14 is another embodiment of a separate insù- `
lating element to be inserted between adjacent insulating members; and Figure 15 is still another embodiment of a separate insulating element to be inserted between adjacent insulating members.
Description of the Preferred Embodiments : ' Referring to the drawings in detail, Figure 1 shows a ``:-portion of the outer surface (hot face~ of an insulating '~
mat, generally designated by the reference character 20, composed of a plurality of strips 22 which are cut trans-versely from a ceramic fiber blanket: (not shown?. As indicated heretofore, these ceramic fiber blankets are -generally provided in widths of several feet, of thick-nesses generally ranging from one-si~teenth of ~n inch to three inches and of almost any desired length; the manufacturer generally rolls up the blankets lengthwise x-so that, when supplied, these blankets are in the form of rolls whose diameters are dependent upon the length of material in the roll. When the strips 22 are cut from the fiber blanket they are cut in a direction of the thick- `~
ness perpendicular to the width and length so that the lowermost strip 22 shown in Figure 1 has a dimension T
which represents the thickness of the fiber blanket from ;~
which the stri~s 22 are cut.
The str~ps 22, after they are cut from the fiber ,,`; , blanket, are placed on edge adjacent each other until the desired width of mat is obtained as shown in Figure 1.
Obviously, the number of strips required will depend upon `',''.'~ , ~ '' " .' -8- ~

the thickness T of the fiber blanket from whi,ch the strips are cut. If a fiber blanket could be provided of thickness twice that of T, then only one half of the number of strlps shown in Figure 1 would be required.
Furthermore, i~ it were possible to provide a fiber blank-et having a thickness equal to the width of the resulting block or mat therefor, then only one such strip would be --employed in connection with each insulating block.
The strips 22 are held together by any convenient means; as best shown in Figures 1 to 3, the strips 22 are held together by means of a plurality of stainless steel ~ -wires 24 which run transverse to the strips approximately ~ -one-half inch from and parallel to the cold face 26 of the mat. The ends of the wires 24 are bent at right angles as shown so as to be retained in position. Various methods and means can be used in conjunction with these wires 24 to attach the mat 20 to a sheet or block of backing type insulation 28 ~see Figures S and 6); for example, a plural-ity o~ hairpin-type devices 30 can ~e placed over the wires 24 at various positions along their length so as to project down below the cold face 26 of the mat 20. Actually, these pins 30 will be driven into the block of backing type insu-lation 28 and, preferably, these hairpin devices 20 will be of the self-clenching type when they are urged against a hard surface as will appear hereinafter.
Although the mat shown in Figures 1 and 2 (and the resulting insulating member comprised thereof) is represent-ed as having a width of approximately one foot and a length of possibly several feet, the preferred shape is shown in Figures 4 to 7. The resulting insulating member shown in these figures would have a nominal twelve inch by _g_ ' ' . , , ~ . ,,, . . ! , - ~039947 ~ :
twelv~ inch face size and a 2300 F temperature rating~
The actual face size will be 12 1/4" x 12 1/4", the additional 1/4" insuring fullness in the installed insula-tion while providing a net twelve inch by twelve inch ~-coverage. Intermediate strips 22' and the outer strips 34 ~later to be described) are cut to their respective sizes from one inch thick ceramic fiber blanket. The block of insulation 28 is mineral block insulation which, in this case, is cut to a size two inches thick, ten inches wide ;-and twelve inches long. Since the outer strips 34 overlie the longitudinal side edges of the block 28, these strips would be two inches longer (in the vertical direction as they appear in Figure 7) than the intermediate strips 22'. ~` -`
It might also be mentioned that a hole 36 is drilled in the center of the block 28 so as to receive a stud (later ~ ;
to be described). `
Parts 34 and 22' are now laid side by side to form the hot face and are secured together by means of the stainless steel wires 24 which are bent ninety degrees at `
the ends to hold them in placa. As shown in Figures 4 and 5, two such wires 24 are provided for the insulating member shown in these figures, although additional number of wires ., .
could be provided if desired. ~;~
The next step in the assembly of the insulating member involves the installation of the stud which will now be ,;~
described; The stud comprises a central shank 38 having nut 40 threadedly mounted at the upper end thereof. A
washer 42 is provided on the shank 38 immediately below ` -the nut 40. When installed, the washer 42 will rest against the upper surface of the block 28. The lower end ~ -of the shank 38 is provided with a stud tip 44 of rela-tively smaller cross sectional area. Also ;~

-` ~0399~7 mounted on the lower end of the shank 38 are a ring retainer 46 received in the groove 48 and a ring-shaped ceramic arc shield 50 which is secured to the ring 46 by cement or in any other suitable manner. The purposes of the foregoing elements will be described hereinafter in greater detail.
At any event, after the stud (with associated elements attached) is inserted into the hole 36 in the manner described above, the prior assembly of parts 22', 34 and 24 are placed over the block 28 with the lower parts of the side strips 34 overlying the two longitudinal side edges of the block 28.
~our hairpin-type stainless steel fasteners 30 (two for each wire 24) are now inserted into the seams between the strips 22' so as to engage the wires 24. These fasteners 30 are driven through and clenched against the back surface of the block 28.
By providing a hard surface, preferably steel, below the block 28 when the fasteners 30 are inserted, the lower ends of these fasteners will clench towards each other as shown in Figure 5.
When the tool ~not shown) for inserting the fasteners 30 is withdrawn from the seams, the strips 22' will return to their original position without leaving any gap or àperture because of the inherent resiliency of these strips.
The resulting insulation member, now complete,;~s ready for installation against a furnace wall 32 by means of a stud welding process which is more fully described in U. S. -Patent, 3,706,870 issued December 19, 1972 in the name of Sauder et al, and entitled "Method and Apparatus for Stud Welding"~
The method and apparatus for stud welding forms no part of the present invention but is , ~ .

~ 039947 described b~iefly hereinafter merely to show one manner of attachment of the insulating mem~er 20' to a furnace wall. A ~"
stud welding gun 52 is inserted into the central seam between the middle strips 22' until the lower end of the gun engages the nut 40 of the stud. The stud gun is triggered and current flows ~ - `
into the shank 38 and into the tip 44. The tip 44, because of its~
relatively small cross sectional area burns away and thus starts ~ -an arc. The stud shank 38 does not itself move at first because `- -it is supported by the self-locking ring retainer 46 which is ;
retained in the groove 48 as indicated heretofore. As best `;-shown in Figure 10, the ring retainer 46 is provided with a plurality of radial fingers 54 which project into the recess .~--48 to hold the ring 46 in position. As the welding operation continues, the intense heat of the arc burns away the fingers 54, thus allowing the stud shank 38 to plunge into the molten metal formed by the arc. At this point, the weld is completed and the gun can be withdrawn. It should be mentioned, however, -:
~hat the ring retainer 46 and the firlgers 54 thereon are care-fully sized so that the fingers will burn away, melt, or soften , `
in approximately two tenths of a second, or within whatever period of time is deemed appropriate, all as set forth more - ~
fully in the aforementioned U. S. Patent 3,706,870. `~ `
Now, it may be desirable to tighten the nut 40 on ~
the shank 38. This can be done by merely rotating the gun : -about the vertieal axis of the shank. It might be mentioned that the lower end of the gun (or extension thereof, if desired) is ~ovided with a hexagonal opening corresponding to the size of the nut 40 and of suf icient depth to accommodate for the upper end of the shank 38 after the nut is tightened thereon. ~hus `
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1039g47 the gun 52 serves a secondary function as a wrench for the nut. When the stud gun is withdrawn, the resiliency of the ceramic fiber strips will cause the strips to'return to their original position thus concealing and protecting the studs from the severe heat in the furnace.
Returning now to further consideration of Figures 4 and 5, it should be noted that the end strips 34 of the insulating member 20' are preferably provided with a plu- -rality of one inch deep cuts 56 spaced approximately one inch apart from each other so as to relieve possible shrinkage stresses on parts 34 only.
As shown in Figure 11, it may be desirable to arrange the blocks 20' of Figures 4 through 6 in such a manner that the strips of adjacent members are at right angles to each other to give a resulting criss-cross appearance similar to that of parquet flooring. As indicated hereto-fore, the arrangement of the fibers is such that they are oriented essentially in planes which are perpendicular to the furnace wall. This tends -to el,iminate or minimize the occurrence of cracks which result from heat shrinkage of ceramic fibers. The arrangement shown in Figure 11 tends to minimize or offset lineal shrinkage of the strips themselves.
The method and apparatus for insulating a furnace wall must be adaptable to walls which do not correspond, dimensionally, to the usage of nominal twelve inch by twelve inch insulating members. Also, it is recognized that the method and apparatus for insulating a furnace should be adaptable to furnaces which have irregularly 3~ shaped burner blocks and flue openings. As shown in Figure 12, it is possible to arrange and attach a , 1()39947 pluralit~ of insulating members 20' to the surface 32' ~ `
of a furnace not readily adaptable for the close end-to- ` `
end, side-to-side, arrangement shown in Figure 11. In ~`
the case of Figure 12, spaces 58 are provided between adjacent insulating members 20' in longitudinal or trans- `-verse or both, directions, depending upon the dimensional `
limitations of the furnace. The resulting spaces 58 can ~
now be filled with specially folded ceramic fiber blankets -such as shown in Figures 13, 14 and 15. The three fillers shown in the latter three figures are constructed in sub-stantially the same way as the strips 22; that is, they are cut from a one inch thickness of four pound density j ceramic fiber blanket and folded over. -In Figure lS, there would be a single sheet 6Q which is folded once so that its upper edges 62 provide the same type of end or edge fiber exposure referred to herein. If the resulting space is larger than two inches wide, then ~
it is possible to go to the configuration shown in Figure ;;
13 which is comprised of two strips 64 and 66, which are cut in the same manner described above. The central strip 66 is relatively narrow in a vertical direction and the ; ~
outer strip 64 is sufficiently wide that it can be folded - -around the central strip 66 as shown, the upper surfaces ;~~-of strips 64 and 66 both providing the end or edge fiber .; .
arrangement referred to above.
Again, if the resulting space between adjacent insu- -~
lating members 20 or between an insulating member 20 and :~
a duct, etc. is greater than three inches, then it might be desirable to use the config~ration shown in Figure 14 where an additional central strip 68 is provided. This ~,.", :' :

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~039947 strip 68 will lie adjacent the strip 66 and an outer strip 70, slightly greater in width than the strip 64 will be folded over the central strips 66`and 68 to provide the arrangement shown.
The different embodiments shown in Figures 13, 14 and 15 can be held in place by ceramic cement, stainless steel wire or by the friction between the fibers alone.
Further Embodiments and Modifications Whereas the method of assembling the mat as described in relation to Figures 1 to 3 has been set forth in terms of wires 24, fasteners 30, etc. it should be understood that other methods could be employed to hold the strips together and to attach them to the backing insulation block. For example, the ceramic fiber strips could be attached to each other by means of suitable ceramic cements or mortar materials which are preferably utilized in the area adjacent the cold face of the fiber mat. Also, although the mats have been shown as being connected -to a backing insulation block prior to appl~cation to a furnace wall, the mats could be applied directly to the furnace wall.
As far as thé manner of fastening is concerned, the foregoing disclosure indicates that the mat of Figure 1 or the composite block of Figure 4 can be attached to a "
furnace wall by means of mortar, ceramic cement or various metallic fasteners. Since the ceramic cement or mortar will generally be located adjacent the cold face of the insulating member, there should be no particular high temperature problem as far as the cement or mortar is concerned; however, where metallic fasteners are concerned, ~
it is generally recognized that alloy pins, bolts, ;
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w~shers and screws which could be used as fasteners have a maximum temperature limit in the range of 2000 to 2100 F.
By "burying" or imbedding the fastener in the insulating member at a position spaced from the hot face thereof, as disclosed in the present invention, it is possible to use alloy pins, bolts, etc. without, at the same time, exposing these metallic fasteners to such high temperatures as would interfere with their effectiveness. ~ - `
Although it is indicated that the mat of Figure 1 r,~ :
could be applied directly to a furnace wall by means of ceramic cement or mortar, it is possible to precondition the cold face of the mat to permit the use of the stud welding method of attachment disclosed herein. For exam- `` `
ple, if a layer of cement or mortar is imbedded in the mat `
along the cold face thereof and allowed to harden, it is obvious that the welding technique and fas~eners described in connection with Figures 7 to 10 could be employed, ~
although a shorter shank 38 obviousLy would be necessary. `
The making of such a cement or mortar layer at the cold face of the mat could also be done in connection with the , use of a high temperature cloth or stainless steel wire mesh which would be applied to or imbedded in the mortar layer at the cold face of the mat to improve the fastening -capabilities thereof.
, Referring now to Figures 4 through -7, a suitable in-sulating block 20' designed for operation at 1800 F is one where the backing block or mineral block 28 is about two inches in thickness and the strips 22' are appro~i-mately one inch in width giving a total width of the block, from the cold face to the hot face thereof, of about three inches. ~ suitable insulating block 20' -16- `

: , iV39947 designed for operation at 2600 F-is one where the mineral block 28 is also two inches in thickness but where the strips 22' are four inches in thickness giving an overall dimension of six inches from the cold face to the hot face. By using strips 22 varying in width from one inch to five inches or more, depending upon the re-quirements of the particular furnace, it should be appa-rent that insulating blocks and/or mats could be employed to cover the recommended range of 1600 F to 2800 F.
Although the block 28 has been referred to as a mineral block whose composition and properties are well recognized in the art, it is also possible to use asbestos block or calcium silicate block, these blocks being relatively rigid backing material for the mat. The strips 22 or 22' of the ceramic fiber mat 20 or 20', respectively, are preferably cut from a ceramic fiber blanket having a density of four pounds per cubic foot.
It is understood that the manufacturers provide ceramic fiber-blankets which are available Ln densities ranging generally from three to fourteen pounds per cubic foot.
In the specific examples referred to herein, the ceramic fiber material has a density of four pounds per cubic oot. However, it should be understood that there might be portions of the furnace where the lining would be sub-ject to gas currents which would give rise to erosion problems and, also, that the furnace might have various access openings which would require a lining of greater physical strength or density upon or surrounding the -openings; in either of the latter two cases it might be ;` ~
desirable to use a ceramic fiber material of a higher ~`
density in the available range referred to above.

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~aturally, it is desirable to insulate a furnace -wall in such a manner that the outside (cold face) of the furnace is at a minimum temperature. However, it is recognized that this minimum temperature will be dependent upon a number of different factors including, but not limited to, the type, thickness and strength of the out- :
side furnace wall; and prevailing air currents outside of the furnace wall. The use of the present invention will provide an outside temperature varying between 200 F
and 350 F which is considered to be an acceptable range. -The preferred embodiment of the present invention, ` -as disclosed above, describes the high-temperature insula- ~ ~
ting fibers which constitute the mat as "ceramic" fibers. ~ ;
l~owever, this invention should not be tied down to any precise definition of "ceramic"; any high temperature insulating ~iber which possesses properties similar to the ceramic fibers indicated hereirl and capable of operating above 1600 F could be used in conjunc-tion with the present invention and should be considered as falling within the scope thereof.
Whereas the present invention has been descrlbed in particular relation to the drawings attached hereto, it should be understood that other and further modifica-~ j; .
tions apart from those shown or suggested herein may be made within the spirit and scope of this invention.
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Claims (27)

1. An insulation module for lining the interior walls of a furnace, comprising a rigid block of refractory material having two opposed flat sides, one side being the cold face for attachment to the furnace wall and the other side being the hot face for exposure to the furnace heat, a resilient fiber insulation mat forming at least the hot face and being held flat within the rigid block prior to installation on the furnace wall, the fibers in the insulation mat being generally randomly oriented in planes, such planes being substantially perpendicular to the hot face.

2. An insulation module according to claim 1 further comprising a hard surface self-contained within the rigid block prior to installation on the furnace wall and being hidden beneath the hot face and against which a fastener can bear to secure the insulation module to the furnace wall.

3. An insulation module according to claim 1 further comprising an internal fastener self-contained within the rigid block prior to installation on the furnace wall and being hidden beneath the hot face, whereby the-cold face of the insulation module may be fastened to the furnace wall without direct exposure of the fastener to the heat at the hot face.

4. An insulation module according to claim 1 further comprising a rigid base forming the cold face of the rigid block, the fiber insulation mat being affixed to the rigid base.

5. An insulation module according to claim 4 wherein the fiber insulation mat is secured to the rigid base with an adhesive bond.

6. An insulation module according to claim 1 wherein the fiber insulation mat includes a number of strips of fiber insulation cut from a fiber blanket and arranged in side-by-side relation.

7. An insulation module according to claim 6 further including strips of fiber insulation attached to the side edges of the rigid block.

8. An insulation module according to claim 6 wherein the strips of fiber insulation are connected to each other by a number of wires extending transversely through the strips.

9. An insulation module for lining the walls of a high temperature furnace comprising a rigid block of refractory material pre-assembled prior to installation on the furnace wall, the block having two opposed flat sides, one side being the cold face for attachment to the furnace wall and the other side being the hot face for exposure to furnace heat, a rigid base member forming the cold face within the rigid block, a resilient fiber insulation mat being affixed flat to the base member and forming the hot face, the fibers in the insulation mat being generally randomly oriented in planes, such planes being substantially perpendicular to the hot face.

10. An insulation module according to claim 9 wherein the base member comprises a substantially rectangular mineral block.

11. An insulation module according to claim 9 further comprising an internal metallic fastener self-contained within the rigid block prior to installation on the furnace wall and hidden beneath the hot face, whereby the cold face of the insulation module may be fastened to the furnace wall without direct exposure of the fastener to the high temperature heat at the hot face.

12. An insulation module according to claim 9 wherein the fiber insulation mat includes a number of strips of fiber insulation cut from a fiber blanket and arranged in side by side relation.

13. An insulation module according to claim 12 including strips of fiber insulation attached to the side edges of the rigid block.

14. An insulation module according to claim 12 wherein the strips of fiber insulation are connected to each other by a number of wires extended transversely through the strips.

15. An insulation module according to claim 14 further including staples surrounding the wires extending through the strips of fiber insulation and extending into the base member for attaching the fiber insulation mat thereto.

16. An insulation module according to claim 9 including a washer centrally located against the face of the base member at the interface between the base! member and the fiber insulation mat, the washer being provided with a central hole, the base member being provided with a hole in alignment with the hole in the washer and extending through the base member to the hot face, a bolt extended through the holes in the washer and the base member, and a threaded nut threadedly engaging the end of the bolt lying adjacent the washer.

17. An insulation module for lining the walls of a high temperature furnace comprising a rigid block of refractory material being preassembled prior to installation on the furnace wall of the block having two opposed major faces, one major face being the cold face for attachment to the furnace wall and the other major face being the hot face for exposure to furnace heat, a rigid base member forming the cold face within the rigid block, a plurality of strips of resilient fiber insulation being arranged in side by side relation and being affixed upon the base member on the side opposite the cold face to form the hot face of the rigid block, the strips being cut from a fiber blanket and being arranged in such a manner that the fibers in such strips are generally randomly oriented in planes, the planes being substantially perpendicular to the cold face.

18. An insulation module according to claim 17 further comprising additional strips of such fiber insulation affixed around the side edges of the base member adjacent the hot face and being flush with the hot face.

19. An insulation module for lining the walls of a high temperature furnace and being preassembled prior to instal-lation, comprising:
a relatively rigid block of refractory material having a flat side for attachment to the furnace wall as the cold face, said block having substantially centrally located opening extending at right angles to the cold face;
a washer disposed on the surface of said block remote from said hot face and having a hole therein aligned with the opening in said block;
a metallic stud extending through said hole in said washer and through said opening in said block;
a threaded nut threadedly engaging the other end of said stud and overlying said washer;
a plurality of strips of ceramic fiber blanket dis-posed in parallel side-by-side arrangement over the surface of said block remote from said cold face and forming a ceramic fiber mat completely covering the face of said block, the fibers in said mat being generally randomly oriented in planes, the planes being generally perpendicular to the cold face of said block, said mat also including strips of ceramic fiber at the side edges thereof extending downwardly to said cold face to cover the edges of said block.

20. An insulation module for lining the walls of a high temperature furnace and being pre-assembled prior to instal-lation, comprising:
a substantially rectangular mineral block having a cold face for attachment to the furnace wall, said mineral block having a substantially centrally located opening extending through the thickness of said block;
a washer disposed on the surface of said mineral block opposite the cold face and having a hole therein aligned with the opening in said mineral block;
a metallic stud having a shank portion extending through said hole in said washer and through said opening to the cold face of said mineral block, the end of said stud adjacent said opposite surface of said mineral block terminating in a stud tip of relatively smaller cross-sectional area than said shank portion, said shank portion leaving a groove therein adjacent said stud tip, a ring retainer surrounding said shank portion and having radially inwardly projecting fingers received in said groove;
a ring-shaped arc shield surrounding said stud tip and being attached to said ring retainer, a threaded nut threadedly engaging the other end of said stud and overlying said washer;
a plurality of strips of ceramic fiber blanket dis-posed in parallel side-by-side arrangement over the surface of said mineral block remote from said cold face and forming a ceramic fiber mat completely covering said mineral block, the fibers in said mat generally being randomly oriented in planes, the planes being substantially perpendicular to the cold face of said block, said mat also including strips of ceramic fiber at the side edges thereof extending downwardly towards said opposite surface of said mineral block to cover the edges of said mineral block;
a plurality of wire fasteners extending transversely through said fiber strips and being bent at the opposite ends thereof to hold said strips together, said wire fasteners being substantially parallel to each other and to said one surface and being located in said fiber mat adjacent the interface between said mat and said mineral block; and a plurality of hairpin-type fastening means surrounding each wire fastener and extending into said mineral block to secure said mat to said mineral block.

21. An insulation module for lining the interior walls of a furnace, comprising two opposed flat sides, one side being the cold face for attachment to the furnace wall and the other side being the hot face for exposure to the furnace heat, a resilient fiber insulation mat forming at least the hot face, the fibers in the insulation mat being generally randomly oriented in planes, such planes being substantially perpendicular to the hot face.

22. An insulation module according to claim 21 further comprising a hard surface against which a fastener can bear to secure the insulation module to the furnace wall.

23. An insulation module according to claim 21 further comprising an internal fastener self-contained within the module prior to installation on the furnace wall and being hidden beneath the hot face, whereby the cold face of the insulation module may be fastened to the furnace wall without direct exposure of the fastener to the heat at the hot face.

24. An insulation module according to claim 21 further comprising a rigid base forming the cold face of the module, the fiber insulation mat being affixed to the rigid base.

25. An insulation module according to claim 24 wherein the fiber insulation mat is secured to the rigid base with an adhesive bond.

26. An insulation module according to claim 21 wherein the fiber insulation mat includes a number of strips of fiber insulation cut from a fiber blanket and arranged in side-by-side relation.

27. An insulation module according to claim 24 wherein the rigid base comprises a wire mesh.