US1756031A - Air-cooled furnace block - Google Patents

Description

b l' 930. v. G. LEACH 1,756,031

7 AIR COOLED FURNACII'} BLOCK Filed May 29, 1926 2 Sheets-Sheet 1 Vernon G. Leach April 29, 1930. v. G. LEACH 1,756,031

AIR COOLED FURNACE BLOCK Filed May 29, 1926 2 Sheets-Sheet 2 E. .25. j 75%1 I 315- Z I IL.

| II II II Verezozz 6- [each I bottom of t e block.

' Patented I emu " --1: nmon alea'ua as, 1826. Serial No.- 112,517.

' This invention relates to furnace blocks desi ed more articularly for the construction 0 air cooled furnace walls. They are also adapted, however, for the construction of 6 heat economizers,and other purposes.

' Blocks for aircooled furnace. walls have been designed having vertical passages through the blocks communicatin with horizontal lon 'tudinal' grooves in t e top and Blocks forrairicoolede furnace 'walls' are subjected to very trying conditions dueto strains and stressesset up-by great variations 7 intemperature betweenthe difierent parts of the lock. While this is true of any furnace wall it is es eciallyiso where the blocks are, provided wit passages for cold air. In

.suc'h cases the difference in temperature between the front and back portion of the I i blocks ma easily be as high as 500 C. If the front an back portions are connected at their center portions only the front and backv portions are free to expand and contract independently without producingK strains in the connecting portions ofbloc ever, as in the constructions heretofore proposed the front and back portions of the block are connected peripherally the full effect of relative expansion and contraction of such portions is thrown onto the connecting portions of the block.

All of the desirable characteristics of firebrick, such as high refractoriness, and superior behavior against. spelling, slugging, shrinkage and-deformation, cannot be developed to a maximum degree in one product. The brick may be strong in. some respects and relatively weak in others, or, as is usually the case, the various properties may all be developed to a medium degree with none of them outstanding.

In order to resist sla s the brick should be of dense, finely oun material, and hard burned to keep t e permeability to a minimum. Slags tend to seep into the lar er pores, surround individual grains of c ay and remove them either mechanically or by solution. On the other hand, a dense, finely ground and hard burned block has a greater tendency to spall than a coarse, porous, light If, how-' burned block. Then in addition to spalling, there ma be pinching caused by the hot ends; of t e brick expanding more than the cooler portions with the result that the ends are placed under tension, and, bein weak under such stresses, are torn off and all into the furnace.

Both spalling and pinchin are reduced very largely by connecting t e front and bac portions at their center portions only giving much greater freedom of expansion and contraction than is the case with blocks havin their front and back portions connecte peripherally.

Hence, by using central connecting means, blocks of greater densit of more finely ground material and bar er burned may be used without sacrificing resistance to spallin and inchin ne 0 the principal objects therefore of the present invention is to provide a furnace block in which strains and stresses due to variations in temperature in different portions of the block are reduced to a Other and further important objects of this invention will be apparent from the dis.- closures in the specification and the accompanying drawings.

This invention (in a preferred form), is illustrated in the drawings and hereinafter more fully described.

On the drawings:

Figure 1 is a vertical section through a furnace with walls built of blocks constructed in accordance with the present invention.

Figure 2 is a vertical transverse section through a wall built of modified form of con- 'struction of blocks.

and 4 but alsoto those shown in portion 12. This central 40 12 of one bloc o'njthe" ne' VII-VII 10 halves adapted to be .united, either prior to or at the'time the wall'is built. For convenience the blocks ,will be'described as if all were constructed-integrally and this applies not only to the blocks shown in Figures 2, 3,

6,7, and 8. r

The blocks shown in Figures 1 to t inclusive comprise a front portion 10 and a rear portion 11 connected together by a central ortion is of less width than the block an preferably decreases in thickness towards both top and hot- 'tom. Further, to facilitate the flow ofair through the wall the central portion 12 is. referably of here the portions 10 and 11 join the portion streamline cross-section.

12' the surfaces of the block are advantageously rounded to avoid sharp corners at which cracks areli'kely to develop. As the central portions 12 are of less width than the the furnace wall.

In building a wall of such blocks the latter are arranged-in staggered relation, as shown more particularly in Figures 1 and 3 so that the air impin es first on the central portion and then on that of another and cannot flow along any one path wholly unim eded. In this way the transference of heat rom the'blocks to the air used to cool the furnace walls is greatly facilitated.

As the central portions 12 are of stream line cross-section the formation of dead air spaces is avoided. The avoidance of sharp entering angles also serves the same urpose.

Underthe intense heat generated in a furnace the blocks or cementing-material therebetween is apt to disintegrate or crack and some at least of the blocks are, therefore, preferably locked to and supported by the e'xternal'wall of the furnace. In Figure 2 this external wall is a brick wall 14 through which extend bolts 15 having hooked inner ends 16 adapted to enter recesses-17 in the blocks."

In this manner each block. may be held in place indeEendently of the others and also,

not being onded to the external wall, may be replaced without removing or'disturbing any of the other blocks.

In practice the bolts 15 will not be ti litened until after the furnace has been red igures 5,

once to allowthe wall to assume a more or less permanent set. These bolts 15, serve to prevent not merely the falling of the wall in case some of the lower blocks crumble, but also bulging, leaning or distortion of the wall as a whole without specific complete failure of any individual blocks.

.In a furnace wall the parts corroded most rapidly are those along the joints between the blocks. With the construction shown the joints come at the thinnest parts, that is where the cooling effect of the air has the greatest effect. Moreover, to aid the cooling effect of the air on such parts the cement used is preferably one having a relatively high heat conductivity. .Such a cement may e made by mixing such materials as carborundum, alundum or chromite with a suitable binder such as fireclay, silicate of soda or wood pulp. In Figure 4 a diiferent form of external wall is shown comprising a sheet iron or steel frame 18 with a back 19 formed of cementitions material of low heat conductivity apertured for the assage of the bolts 15.

The blocks s own in Figures 5, 6, 7, and 8 are formed with cavities 20 inside the portions 12.to aid the transference of heataway from the front portion of the block. This is In case the blocks crack through the central portion thereof air will flow into the fur-- nace from these cavities and so cool the edges of the cracks in the blocks and retard their corrosion.

In Figure 8 a still further modification is shown in the form of ribs 22 arrangedvertically on the center portions 12 of the blocks. These ribs increase the area exposed to the coolin air and therefore facilitate the transfer of eat to the latter.

It will be understood that blocks constructed in accordance with the present 'invention may be used to form an arch or bridgewall as well as the sideand bottom walls of a furnace. The blocks may also be set vertically, horizontally, or leaning.

I am aware thatmany changes may be made, and numerous details of construction may be varied'through a wide range without departin from the principles of this invention, an I therefore do not purpose limiting the patent ranted hereon, otherwise than necessitated y the priorart.

I vclaim as my invention; 7

, 1. A furnace block composed of fire clay having two rectangular portions integrally 'connected'by a tie which has a portion of anthe A sisting material having two rectangular portins connected by a hollow portion of less width than the block, and a filling of material having a relatively high heat conduc- .tivity in said hollow port-ion.

3. As an article of manufacture, a furnace block of two sectlons, each section comprising two rectangular end portions and an integral tic of less width than the rectangular end portions and having a'face in the same plane as one face of the rectangular end portions, the said integral tie having a longitudinal recess in that face which is in the same plane as one face of the rectangular end portions, Whereby when the two sections are cemented together a block is formed with a tie having'a hollow portion.

4. As an article of manufacture, a furnace block of two sections, each sectioncomprising two rectangular end portions and an integral connecting portion which is substantially stream-lined semi-oval in vertical section, the

said connecting portion having a face in the same plane as one face of the rectangular end portions and having a recess in that face.

5. As an article of manufacture, a furnace block of two sections, each section comprising two rectangular end portions of unequal thickness and an integral connecting portion which is substantially stream-lined semi-oval in vertical section, the said connecting portion having a face in the same plane as one face of the rectangular end ing a recess in that face.

6. As an article of manufacture, a furance block of two sections, each section comprising two rectangular end portions and an integral connecting portion which is substantially stream-lined semi-oval in vertical section, the said connecting portion having a face in the same plane as one face of the rectangular end portions, the said connecting portion having portions and hav-' tially stream-lined semi-oval in vertical section, the said connecting portion having a face in the same plane as one face of the rectangular end portions and a recess in that face, the connecting portion having curved end surfaces merging into the adjacent surfaces of the rectangular end portions, the said sections being adapted to be laid together to form a block having rectangular end portions and an cvate-cylindraceous connectlng portion, the said blocks being laid adjacent each other at their rectangular ends, and the courses being laid to present tortuous conduits for cooling air.

In testimony whereof I have hereunto subscribed my name.

VERNON G. LEACH.

curved end surfaces merging into adjacent surfaces of the end portions whereby to avoid sharp angles.

7. As an article of manufacture, a furnace block of two sections, each section comprising two rectangular end portions and an integral connecting portion which is substantially stream-lined semi-oval in vertical section, the said connecting portion having a face in the same plane as one face of the rectangular end portions and having a recess in that face, the

said connecting portions having curved end surfaces merging into ad acent surfaces of the end portions whereby to avoid sharp an gles.

8. A furnace wall composed of a plurality I of furnace blocks laid in courses, each block being of two sections, each of said sections comprising rectangular end portions and an integral connecting portion which is substan-

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