US 2148054 A
Description (OCR text may contain errors)
\ 55 cable in all cases in which molten metal does not Patented Feb. 21, VV1939 'A UNITED STATES PATENT OFFICE' Mon'rARLEss narcxwonx Josef Berlek, Radenthein, Austria, assignor to Oesterreichisch Amerikanische Magnesit Aktiengesellschaft, Radenthein, Austria, a hintstock company Application December 12, 1936, Serial No. 115,606
y In Austria March 11, 1936 Claims.
When refractory bricks are laid. to 4form.
masonry which is not free to expand, as
case for example when a rigid or non-yie ding sheet metal jacket does not leave sufficient play for the expansion of the refractory furnace 1ining enclosed thereby, that-is to say more particularly in the case of revolving cylindrical kilns or rotary furnacesgexpansion joints must be provided to prevent the ends of. the bricks from becoming crushed by the expansion pressure set up by the heating-up oi the furnace. 'For this purpose it has been proposed to lay betweenthe bricks strips of pasteboard of suitable thickness which keep the bricks suitably spaced during vthe.
work of laying the same, and which afterwards burn away/when the furnace is heated.I It has also provedruseful, in laying magnesite bricks, to make provision for expansion due to heat by inserting in the main' joints, sheet iron which becomesv plastic and finally melts when the furnace is heated-up. `In this manner account is also taken of the fact that-magnesite bricks'must be laid as far as possible dry, for which reason it is -the general practice-either to lay them without any binder with crepitating joints, or to use 4 as binder or bedding `material special anhydrous mortar (for example tar oil or linseed oil mortar) or even merely dry pulverized magneste: If sheet metal is employed in building up brickworkv of this description a cementing together of the bricks atthe butt joints is also achieved. simultaneously.
' vent lthe occurrence 'of stresses during the heating-up of-brickwork which is not free to expand, that is to say /more particularly in the refractory linings of revolving cylindrical kilnsor rotary furnaces, 'but also in arches and partition walls or the like, use being made, for this purpose, of elements made from metallic sheet material 'for insertion in the joints of brickwork, which material'is of the nature of sheet iron, such elements as are used in the' building up of dry niagnesite brickwork. In accordance with the present invention, however, there are employed for this purpose sheet metal elements of special crosssectional shape. The present method is appli-'- A'n object of the present inventionfis to pre` (Cl. 26S-43) come in direct contact with the refractorylining. 4The nature of the metal used is determined. by the condition that it either will not combine with the refractory material at high temperature or at least will not have any deleterious effect upon this material and particularly on'the refractory nature of this material.
Iron is the preferred p material in the case of the metlod accordingA to the present invention also, if ,only on account of its low price. v
Elements made from metallic material for insertion in the joints of brickwork have in general the disadvantage that their softening under heat progresses slower than the expanding of the bricks, with the result that with elements which are initially at stresses are set up after all in the brickworkat the commencement of heating up, which are capable of loosening the brickwork structure. In order to ohyiate this drawback the bricks are spaced, in accordance with the present invention, to the extent required tp allow for expansion due to heat, by means of sheet metalv strips the spacing capacity of which is increased by virtue of the fact that they .become attened out under pressure before the metal melts. To'
this end there are employed sheet metal spacing elements having projections formed from the material of these elementseither mechanically, for example by bending or stamping, 0r by hand, for example by hammering. 'I'he projections may be formed in a great variety of ways and this I term is used in this description and the accompanying claims in its broadest sense. For exam- I to use' corrugated sheet material in which the l crests .of the corrugations on both sidesare flat.
This method of Vbuildingr up brickwork from refractory bricks without the use-of mortar has the great advantage that the sheet metal spacing elements yield to the expansion of the bricks. Moreover, on account of the shape given to the spacing element, their thickness (including the heights of the corrugations, protuberances, bulges,
- etc.) may be such as to correspond to .the total l maximum expansion of the brick for the `temperature concerned, and that not only without using more material but actually achieving a saving of material. For example, if a rotary cement kiln is to be lined with magnesite bricks amounts to 2%. Consequently ja. spacing oi' 0.02 ==,1.3 mm. is required to enable each brick to expand unchecked when the kiln is being heated up to this temperature. In accordance with the present invention there are used for this purpose, instead of 1.3 mm. massive sheets, material of 0.5 mm. thickness brought up to a thickness of 1.3 mm. in the manner described, for example by corrugation. These two advantages are accompanied, in the case of magnesite bricks or bricks containing magnesia (for example chromite-magnesite bricks), when spacing elements made from sheet iron are used, by the additional advantage'thatI at the commencement .of heating up, owing to abundant scale formation, there become formed considerable quantities of iron oxide which combines with the magnesia to produce magnesium ferrite, with the result that an excellent refractory cement is formed which unites the bricks to a monolithic unit.
'I'he invention will now be described with reference to the accompanying drawing, in which Figs. 1 and 2 show a form of construction of the sheet metal element to be used in accordance with the invention, in en d view and in plan view, respectively. Fig. 3 shows a modified form of construction of a sheet metal element in end View, and Fig. 4 a portion thereof in plan view; Figs. 5 and 6 show a part of the lining of a rotary cylindrical furnace erected in accordance with the invention, in elevation andl in cross-section, respectively.
Referring to Figs. 1 and 2 of the drawing the sheet metal element I for insertion in the joints of the bricks is in profile of corrugated substantially U-shape with fiat crests or waves 2 on both sides, the height'oi' which amounting to about one-and-a-half times' the thickness of the sheet metal from which it is made. The sheet metal is made in sizes approximately equal to that of the surfaces of the brick but the sizes may also be a multiplethereof, as shown inthe horizontal pieces in Fig. 5. The corrugated sheet metal is of such a strength that the corrugations flatten out under a pressure smaller than that endured by the bricks or smaller than the resistance to pressure of the bricks.
The projections of the sheet metal elements may also be in the form 4of protuberances or bulges l as shown in Figs. 3 and 4, which are pressed up and pressed down in the sheet metal, and preferably projecting alternatively from both sides of the sheet metal. i
In the appended claims, theiterm corrugated sheet metal is used to include sheet metal having longitudinal corrugations as well as sheet metal having struck up portions, as described herein and as illustrated by way of example in the appended drawing. I
The sheet metal elements are inserted in the longitudinal and circumferential joints in the lining which is built up of the refractory bricks l 4, as shown in Figs. 5 and 6 and which is encased by a rigid sheet metal jacket or shell 5.
When the furnace is being heated up the bricks expand and compress the sheet metal spacing elements inserted between them, so that the projections on these elements are pressed fiat. The forces set up thereby are relatively slight and can be taken up by the bricks without danger to the structure. As the temperature increases still 'further the spacing elements become soft and oil'er no appreciable resistance to the expansion of the bricks. Finally, the iron melts and is partly squeezed out of the joints, and partly taken up (mainly as lmagnesium ferrite) by the pores of the bricks. IIt will be understood that at temperatures approaching the melting point of the iron, the iron becomes oxidized and it isv the iron oxide that combines with magnesia to form the' magnesium ferrite, formed in ysitu in the adjacent surface portions of the bricks.
According to the provisions of the patent statutes, I have explained the principle and construction of my invention and have illustrated and described what I now consider to represent its best embodiment. However, I desire to have it understood that, within the scope of the appended claims, the invention may be practised otherwise than as specifically illustrated and described.
1. Method of building up refractory masonry, which comprises laying up refractory bricks without mortar, leaving spaces between the said bricks sufficient to allow for expansion of the bricks during a heating up step, and only partly filling the joints by theinsertion of corrugated sheet metal, the metal of said sheet being oxidizable at high temperatures, and said metal and its oxide being lfree from deleterious action on the refractory quality of said bricks, and which sheet inetal elements are adapted to flatten out under the pressure of the expanding bricks, and heating up the thus built up brickwork, for causing expansion of the bricks and thereby atleast partly flattening out the corrugated sheets, and thereafter further Aheating such assemblage suiflciently to soften the metal of said sheets, and allowing oxidation of said softened metal to occur.
2. Method of building up a refractory brick lining in a rotary furnace, which comprises laying refractory magnesia-containing bricks, without mortar, as a lining in a rotary furnace, while leaving sufficient spaces between the bricks to allow for expansion of the bricks during the step of heating up the furnace to a temperature at which iron softens, and partly filling the joints between the bricks by the insertion therein of corrugated sheet iron spacing pieces, adapted to flatten out under the pressure of the expanding bricks, and heating the furnace structure thus built up, whereby firstly the expansion of the bricks, due to the heating, causes the sheet iron spacing elements to become somewhat flattened out, after which, upon heating to higher temperatures, the iron becomes softened and in part oxidized and iron oxide so formedreacts v,with
bricks during the step of heating up the fur-A nace to a temperature at which iron softens, and partly lling the joints between the bricks by the insertion therein of 'corrugated sheet iron spacing pieces, adapted to flatten out under the pressure of the expanding bricks, and heating the furnace structure thus built up, whereby firstly the expansion of the bricks, due to the heating, causes the sheet iron spacing elements to become somewhat flattened out, after which, upon heating to higher temperatures, the iron becomes softened and in part oxidized and iron oxide so `formed is, to some extent atleast, absorbed by the surface portions of said bricks and reacts with magnesia of the bricks to form magnesium ferrite, which is refractory.
` 4. Furnace masonry which comprises refractory bricks laid with open spaces lei t between adjacent bricks sufficient to permit expansion of the said bricks by heating, corrugated sheet metal inserts only partly lling said space-s, said corrugated sheet metal inserts being adapted to be flattened out by the expansion of said bricks during the step of heating up `of said bricks and bedue to high heat, such assemblage being capable of further heating suciently to soften and oxidize the metal insets, whereby the metal oxide can be, in part at least, taken up by the refractory bricks without substantial injury to the re fractory qualities of such bricks. l f
5. A structure as in claim 4, in which the corrugations of said corrugated she-et metal spacing flat tops.
elements have vsubstzamtially JOSEF BERLEK.