US2791116A - Refractory brick having spacer plates - Google Patents

Description

y 7 5 R. P. HEUER ET AL 2,791,116

REFRACTORY BRICK HAVING SPACER PLATES Filed Aug. 19, 1953 INVENTORS- Russell fiearce He we) REFRACTORY BRICK nzwmosrhcnn rmrnsf Russell Pe arce Hel er, Bryn-Ma'wr, and Mervin Adrian Fay; Nat-berth; Pal, assig'lib'rs to" Geilei'i'alf Refraetories' ion'ipaiiy, Philadelphia, Pa.', a" coriiern'tiowof Perm sylvania' Application-August 19; 1'9ss,-seria1 Not-315x94 sedans: ori -72 3's)" t-r'fmtigh'eur.

fiesenliih'g in iu'u'stratisn btm n'ft ih lhiritatien ann referring to the drawings:

Inahe construetien of many types'o furnace's to 'be new at high: temeeratnreg. such! as open hearth: 'steel it is desirable to use suspended"- refraietony n this puhpose consist oh the various Basie ref "ates of win the nrost widelwuse'dflaite mage nests, chrome rrragnesia and Inagnesiawhrome: -It= is custemary' to lay-5 the" ibri'cld with" tntit'lizab'le metal-liosp'ac'ers in the joints. Fr'eqdentlys'" suchbasic brick am used without previous kiln firingzzandiin su'eh cases the metitiiic spacersar" d Ev service of this cnaraetr; faiwre df tlie refractor isprirnarily-Byspalling'a yor th atth nst-end duetd the temperature changes which the hottest part of -theliriek -eiiperienceinthe'cycle'of interthittent" tion Omerurnacez- The c rrteinperarure an the brick a exiiand and contractrap'idly, ana' even taatly the briek fracture andshall ofi aloh'iplanes Whi parallel: to theexposed" faces or the lb rick" add about"one-inch-from the hot e'n'd. This-spa11tng7eaues prematuhe f-ailaret p u 7 In: a' refractdry rcofi-or -wall, eaeh brickhasits hot end exposed to": the i'ntei'ior of the? furnace; while' the sides 'pa'r allel to 'tlie rnaioiaxis of the' bricl extend outwardly from the f interior and are protected from--the- Y may exhibit a temperatur of 000 supported wall: constiuetienst- The rfrazcto- .st'eet is mgr'pea fiswanwpes heaith steel fui nacet A 2,791,116 Patented May 7, 1957 l' gi adie'n 't sheave-vans along the longitudinal axis of the brick;

Afterthe" fur r1ace"is" tapped, the tuma'ce d'o'oi's are open-en, tli'efhel" is shut oil and a'large quantityv of cold char e is placed inthefurnace As a result the hot end of rick'coolsrapidly and its temperaturernay fall to 1000" FL Sincethe cooling is relatively rapidmos-t'of the-temperature change is confined to the'hot' endof the brick, ahdatsorne" interior'point there is relativelylittle loss iiji t'm'perstnre I I fifter charging of the furn'a'ce is c'ornpleted, the fuel is again silp plie'd' to the furnace andthe ho't' end: of" the brick rise tempe atureun il the gradient formerly eXi's'ting is again establishedi Thisf-operatingcycle is" re peated a g'ai'n andag'ain. The brick arethus subjected to repeated straiiis andifinally' fracture develops parallel ti) the Hof'eifd aiid":the hot end: sgalls oif. A newhot end is thus established; and thisissubjec'ted' to similar tieiitineiit aiid 'gi'adually'the brick are des't'royedi If we consider the brick as divided into elements parallel to the longitudinal axis andparallel to'one andtfieh-it willbe' evident that the adherence of e'achele merit"- tb it's" n'eighhdr tends to set up tensile" stresses aerbs the4fot face of-the which tend to increase the tliick iie'ss of 'tfie individual elements when th'ehotface refraetorfcann'ot stan'd, whereupon a; crack will result 0 the hot end-L The defori'rratidnof theele'nients' 'iiek i1iay"ei c eed the strain which the refractory of standing and this wnr produce cracks parthe-T face:

he 'st'r'ain'ss'et up heating'and cooling;

The spacers are usually made of ordina fy 10W car-lion steel, althou'glfthey'can be n'iade of -any oki'diiz' able' construet-idn rnetal or alloy which will operate at the rempe ie of tlie' hot end of the refracto'ry.- It'will'be evi-den" of courseth'atthespacers need not be 'oXidiiable atreonr ternperature so long as 7 they oxidize at furnace temperature, and th'erefore'stainless steel, such as the 18% ehrom-iuin; 8% nickel-grade or the"1'6%" chromium grade" or 'otlter alloys of iron'and chromium" may be used.

The' heafiof thefurn'ace oxidizesthe spacers at the hottest pant of the brick and the iron or other metallic oxiderfermed reacts-with the basic material present 'in the refr-aetory,--suitably magnesia'or impurities in chro ore; The resultant product welds together to toxin: a r nonolith-ic structure which definitely resists cracl -fdrmatiofi.

Oui studies indicate that the-strain set up in the surfaeei'ofthe b rick due to" heating; and cooling are "greater ie the-aransverse dirnensions of the brick are greater.

We have discovered" th'at improved resistance to spall ing is obtained by irnbedding in the brick at the time of molding; aplurality of oxidizable'metallic spacer plates Wliiclfiare placed'in a plane'or planes" parallel tothe major axis of the brickfand preferably approximately parallel to oneof the faces of the brick whi'ch extends-longitudinally in the' 'furnacei thereliy subdividing: the'brickintocor'rioldedt cells-ofi srn'aller" dimensions, which can'- be heated and codled with 1ess*strain-- atthe-outer surface. The

same mysterious action of the spacer plate which minimizes the crack formation when the plate is located at the edge of the brick likewise minimizes the crack formation at the edges of the cells within the brick. Therefore, spalling resistance is decreased due to a combination of the cellular effect on account of reduced dimensions subjected to strain, and the skin effect exerted by the oxidizable metallic spacer subdividing the cells.

While the partition wall between the cells should extend a major portion of the distance across the brick at the hot end (and most desirably at least of each distance) it will be understood that there may be some remaining cross connection between the refractory where the partition does not fully extend across the brick. Likewise while the cell should run the major portion of the length of the brick, it will be understood that considerable benefit will be evident if the partition is located at the hot end and extends for a distance of even two or three inches from the hot end. Naturally for best results the cells should be separated for the major portion of the length of the brick beginning at thehot end.

The brick mix employed may, for example, be magnesia or refractory material high in magnesia, such as dead burned magnesite or electrically fused magnesia. It is important that the refractory material be of a basic nature, since certain refractories such as silica would react with the metallic spacers when they oxidize and would form fusible slags, destroying the roof. Chromite may be usedinstead of part of the material high in magnesia. For example mixtures of chromite with magnesia, containing for instance 75% of chromite and 25% of dead burned magnesite, may be used.

The amount of chromite present may be decreased for example to a composition containing 25% chromite and 75 of dead burned magnesite. Any other suitable basic refractory composition may be employed.

Bonding substances should preferably be added to secure bond without kiln firing. Organic binders such as sulphitepitch, dextrin, glue, gum arabic or inorganic binders such as water solutions of magnesium sulphate, magnesium chloride, sodium dichromate, sodium silicate and the like may be used. The amount of binder used should be suflicient to form a brick which is mechanically strong without kiln firing. Normally the binder will be of the order of one percent on the weight of the brick, and will seldom exceed two percent, and should never exceed five percent.

The pressure of molding the brick will in any case exceed 1000 pounds per square inch (70.3 kilograms per square centimeter), and preferably exceed ,5000 pounds per square inch (351.5 kilograms per square centimeter) and will most desirably exceed 10,000 pounds per square inch (703 kilograms per square centimeter).

Where reference is made herein to a brick it is intended to include any standard refractory shape as well as any suitable block or shape provided with any suitable contour or attachment to engage a suitable hanger or support if any.

Figure 1 shows a brick 20 according to the invention, having refractory material 21 which is comolded with a suitably U-shaped metallic spacer plate 22 having a base of the U 23 which is on one longitudinal face of the brick and opposing arms of the U 24 and 25 which'are on opposed longitudinally extending sides of the. brick;

The arms extend desirably the full dimension or at least a major portion of the full dimension of the brick in the direction in which the arms extend away from the base of the U. 1

In order to interlock with the brick, projections or tongues 26 are lanced from the arms and extend inwardly and are comolded in the sides of the brick.

In the preferred embodiment the side of the brick opposite to the base of the U is provided with a preferably flat metallic plate 27, which preferably extends the full length of the face in the direction of the major axis of the brick, although it will be understood that it may have suitable cutouts for a hanger opening or hanger projection if desired. Tongues or projections 28 are suitably lanced or otherwise formed from the spacer plate 27 and are embedded by comolding in the refractory.

Internal spacer plates or partition walls 30 of which two are shown in spaced relation extend in the direction from the base of the U 23 toward the opposing spacer plate 27 and are desirably secured to the base of the U as by spot welding at 31. The partition plates or internal plates 30 extend parallel to the sides of the U in the form shown, subdividing the brick in the particular embodiment into external refractory cells 32 and 33, beginning at or adjacent to the hot end 34, and internal refractory cell 35, likewise beginning at or adjacent to the hot end.

The refractory cells formed are desirably equal.

It is not important for the purpose of the present invention whether or not the partition plates have tongues or interlocks comolded in the refractory similar to the tongues or interlocks 26 and 28.

The partition plates will, where desired, extend the full length of the brick in the direction of the major axis as shown in Figure 1, but in some cases the partition plates 30' are shortened as shown in Figure 2, so that room will be permitted for a hanger socket at the cold end of the brick.

It will be understood that the molding pressure in forming the brick is applied between the face of the brick located at the base of the U 23 and the plate 27 so that the internal plates and the external plates are intimately associated with the refractory by comolding. Thus the internal plates extend across the major portion of the dimension of the brick in the direction of molding.

All of the plates comolded with brick are desirably 35 of oxidizable metal such as steel as already explained.

The spacers and the partition plate are preferably of sheet or plateabout A inch thick, although thicker or thinner spacers may be used. Spacers and partition plates thicker than inch are not recommended because of the tendency of the metal to melt out rather than oxidize, and spacers thinner than ,4 inch are not recommended because the oxidized layer formed is not adequately thick.

The molded brick are desirably dried for about 24 hours, after which they are ready for use without kiln drying.

.It will be evident that while the U-shaped plates will be preferred, flat plates on the external faces will some times be desirable.

In view of our invention and disclosure variations and modifications to meet individual whim or particular need will doubtless become evident to others skilled in the art, to obtain all or part of the benefits of our invention without copying the brick shown, and we, therefore, claim all such insofar as they fall within the reasonable spirit and scope of our claims.

Having thus described our invention what we claim as new and desire to secure by Letters Patent is:

1. A basic refractory brick composed of a refractory of the class consisting of magnesia and mixtures of magnesia and chrome ore, said brick having generally parallel opposed outside longitudinal faces and a plurality of spaced oxidizable metallic plates extending in comolded relation longitudinally through the interior of the brick transverse to the intended hot face of the brick and over a major cross section of the brick in substantially the same direction as said opposed outside faces, said oxidizable metallic plates dividing said refractory into outside and inside cells between said outside faces of the brick and said plates, and said plates being adapted to react in the inside of the brick with the basic refractory and strengthen the refractory of said cells adjacent to said nesia and chrome ore, having external and internal refractory cells, comolded external oxidizable metallic plates at opposed longitudinal outside faces of the brick, comolded internal oxidizable metallic plates interposed between said external and internal cells and extending through the interior adjacent to the hot face and extending over a major portion of the cross section of the brick, the external and internal plates being adapted to oxidize and the internal plates being adapted to react in the inside of the brick with the basic refractory and strengthen said external and internal cells.

3. A refractory brick of claim 2, further characterized in that the internal plates are generally parallel to the external plates.

4. A refractory brick of claim 2, in which the internal plates and the external plates are directly interconnected.

5. A refractoly brick of claim 2, in which the internal cells and the external cells are of substantially equal size.

6. A basic refractory brick composed of a refractory of the class consisting of magnesia and mixtures of magnesia and chrome ore, said brick having generally parallel opposed outside faces, a plurality of spaced oxidizable metallic plates extending in comolded relation longitudinally through the interior of the brick transverse to the intended hot face of the brick and over a major cross section of the brick in substantially the same direction as said opposed outside faces, and an oxidizable metallic plate extending in comolded relation over a longitudinal face of the brick other than said opposed outside longitudinal faces, and extending in a direction perpendicular to said internal plates, said oxidizable metallic internal plates dividing said refractory into outside and inside cells between said opposed outside faces of the brick and said internal plates, and said internal plates being adapted to react in the inside of the brick with the basic refractory and strengthen the refractory of said cells adjacent to said internal plates.

References Cited in the file of this patent UNITED STATES PATENTS 2,247,376 Heuer July 1, 1941 2,527,063 Heuer Oct. 24, 1950 2,579,050 Ramsay Dec. 18, 1951 2,652,793 Heuer Sept. 22, 1953 2,673,373 Heuer Mar. 30, 1954

Claims (1)

1. A BASIC REFACTORY BRICK COMPOSED OF A REFRACTORY OF THE CLASS CONSISTING OF MAGNESIA AND MIXTURES OF MAGNESIA AND CHROME ORE, SAID BRICK HAVING GENERALLY PARALLEL OPPOSED OUTSIDE LONGITUDINAL FACES AND A PLURALITY OF SPACED OXIDIZABLE METALLIC PLATES EXTENDING IN COMOLDED RELATION LONGITUDINALLY THROUGH THE INTEIOR OF THE BRICK TRANSVERSE TO THE INTENDED HOT FACE OF THE BRICK AND OVER A MAJOR CROSS SECTION OF THE BRICK IN SUBSTANTIALLY THE SAME DIRECTION AS SAID OPPOSED OUTSIDE FACES, SAID OXIDIZABLE METALLIC PLATED DIVIDING SAID REFRACTORY INTO OUTSIDE AND INSIDE CELLS BETWEEN SAID OUTSIDE FACES OF THE BRICK AND SAID PLATES, AND SAID PLATES BEING ADAPTED TO REACT IN THE INSIDE OF THE BRICK WITH THE BASIC REFRACTORY AND STRENGTHEN THE REFRACTORY OF SAID CELLS ADJACENT TO SAID PLATES.

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