US2532990A - Burner block - Google Patents

Description

' E. BLAHA i BURNER Locx Filed June 231945 Dec. s.,l 1950` IN V EN TOR.

Patented Dec. 5, 1950 l BURNER BLOCK Emil Blaha,-'che1tenham, Pa., 'assigner' to selas '5% CorporationV o f America, Philadelphia, Pa., a

corporation of Pennsylvania Application June 23,1945, serial No.` somos i (ol. 15s-1) 11 Claims'.

My invention relates to refractory shapes, such as, for example, burner blocks, flller blocks, roof shapes and the like, and. it is an object to provide an improvement for increasing the life of such refractory shapes employed in walls of heating structures. h

The objects and advantages of my invention will become apparent from the following description and accompanying drawing forming a part of this specification. and of which Fig. 1 diagrammatically illustrates a fragmentary perspective view of a refractory wall for a heating structure in which are mounted refractory shapes embodying the invention; Fig. 2 is a verticalvsectional view, taken at line 22 of Fig. 1, of a burner block embodied in the refractory wall; Fig. 3 is 4; Fig. 4 is a horizontal sectional view taken at line I--l of Fig. 3; Fig. 5 is a perspective view of one form of tie rod employed in thev refractoryshapes mounted in the wall of Fig. 1; and Fig.v 6

refractory wall of Fig. 1 and likefthat of Fig. 5.v

Referring to Fig. 1, I have shownmy invention embodied in a refractory wall IIJ of a heating structure, such as a furnace, for example.v Thek wall I comprises a plurality of preformed refracexample, throughwhich a sultablecombustible fuel mixture ls supplied to the radiator I4.

The distributor caps I5 are threadedly secured at 22 tothe inner ends of the `tubes I'l and formed with a number of longitudinal slots or grooves 23 at the peripheries thereof for vsubdividing the combustible mixture to form a plurality of small gas streams. The gas streams are discharged from the' distributor caps "I5 at 24, as shown in Fig. 4. at which regions a plurality of relatively small burner flames are produced and maintained. The burner flames project outwardly from the distributor caps I5 at regions closely adjacent to and overlying the surfaces of the parabolic radiators I4 within which substantially complete combustion is accomplished. The radiators I l are lis a sectional. view `of another form of tiel rod .employed in the refractory shapes mounted in the v 1 mentary' sectionsy 25' which, when assembled and a vertical-sectional view taken atline 3-3 of Fig. heated to a highly radiant ,condition and the refractory surfaces thereof kreach temperatures of 2800F. and higher whena combustible mixture is supplied to the burner'blocks II comprising a mixture of .air and ordinary city gas having a B'. t. u. rating of about 53,0 v B t. u. -per cubic foot.

The burner blocks `II- are 1 formed` of complejoinedtogether byhigh temperature cement, as

l 'indicatedat 28, provide the burner blocks illustory shapes including a vnumber of burner blocks f Il and ller blocks' I2 of ceramic material. The burner blocks II are'arranged in horizontal rows one above the other, and the blocks I I in one row blocks I I.

maybe staggered with respect tothe blocks II` in the rows adjacent thereto, as shown in Fig. 1` While the blocks II in each row are' spaced from one another by a single filler block I2.I;heblocks includes a cup-shaped radiator I4 of parabolic form, a distributor cap I5, and a passage I6 extending from the bottom. of the radiator to the rear of the block.

Within the passages I6 are disposed burner tubes or sleeves I1 having the inner ends thereof terminating at regions closely adjacent to the inner ends of the passages I6. An intermediate part of each tube I1 is formed with an outwardly. extending shoulder I8 which lits against a collar I9 positioned in a ring-shaped channel or groove 20. Within the outer vend of each tube I1 is secured an end of a conduit 2l. as by cement, for

.trated and justdescribed. The faces of the sections25 which come together maybe. formed with v'cha'. nnels at eaehside of thecentral passage I6 .so that.. when the sections are secured together,

passages will'be i'ormed to anchor bolts 21 in the The bolts 21 project beyond'the rear of each burner block' and are adapted to receive tightening nuts 28.

When each burner block II is initially formed and before the sections 2.5 thereof are united by cement, as justdescribed, the collar I9 is placed l in one section and accurately positioned a definite distance from the radiator I4 with the aid of high temperature cement 20a in the channel or groove 20 in which the collar I9 isv embedded. Similarly, the heads of the anchor bolts 21 are accurately'positloned in one section 25 of each burner block with the aid of high temperature cement, as indicated at 30, before the two sections are united together. i

While the burner blocks yII are formed from a pair of molded refractory sections 25, the illler blocks I2 areshown as one-piece molded refractory shapes. It is to be understood that the burner blocks `I l may also be formed as one-piece refractory shapes.v t

When the refractory wall I0 is employed as a wall of 'a heating structure having a heating space, it is desirable to utilize burner blocks II 3 Y and filler blocks I2 formed of refractory material of such porosity that a poor thermal conductive path is provided through the wall, so that the heat loss from the heating space to the surroundings will be at a minimum. However, the strength of the refractory material is a. function of its porosity.v When refractory material of greater porosity is employed, a poorer thermal conductive path results; but such improvement in the thermal insulating properties of the material is accomplished by sacrince in tensile strength.

The tensile strength of refractory shapes is an important consideration because of the thermal shock to which such shapes are subjected. Each time the heating space is heated from atmospheric temperature to an elevated temperature of about 2500 to 2800 F. and higher, for example, the refractory shapes are subjected to considerable thermal shock. Since Vthe inner faces of the refractory shapes form a part of the inner refractory lining of the heating space and are heated to a hghly radiant condition, the highest concentration of heat occurs at the regions of the shapes at and adjacent to the inner faces thereof. Further, when the shapes are formed of refractory material of poor thermal conductivity and the temperature gradient from the inner faces thereof to the rear surfaces is relatively high, stresses are induced in the refractory shapes.

When the heating space is repeatedly heated to elevated temperatures and then allowed to cool to the ambient temperature, refractory shapes formed of ceramic ma'ter'al of desired porosity are subjected to such thermal shock that cracks and aws may develop which may eventually cause the shapes to split. Stated another way, the tensile strength of the refractory material having desirable thermal insulating properties is insufficient to withstand the stresses and strains induced therein by repeatedly heating the inner faces of shapes of such material to elevated temperatures and subsequently allowing these regions to cool to the temperature of the surroundings.

In the refractory wall III the inner faces of the burner blocks I I are heated to a higher temperature than the inner faces of the filler blocks I2. This is so because of the combustion accomplished at the radiators I4 which heats the surfaces of the latter to a highly radiant condition. However, in many heating applications where a considerable number of burner blocks 'II are mounted in the walls of the heating structure, and especially where the burner wall is at close 'range to the work, the high temperature heated products of combustion sweep past the inner surfaces of the filler blocks I2 at high lineal velocities to heat such regions to a highly radiant condition approaching the temperatures maintained at the surfaces of the radiators I4.

Hence, the greatest concentration of heat occurs at the inner surfaces of the filler blocks I2 and at the surfaces of the cup-shaped radiators I4. When the blocks |I and I2 are formed of refractory material of relatively high porosity to provide a poor thermal conductive path through the wall in which such blocks are mounted, cracks may develop at the regions adjacent to the inner faces of the blocks due to the stresses induced therein, as explained above. This .is especially true when the burner blocks I I are fired to exceptionally high temperatures by reason of the reduced cross sectional area of the blocks at the vicinity of the cup-shaped radiators I4.

When cracks and flaws do develop in the burner blocks at the vicinity of the cup-shaped radiators I4, parts of the blocks may break oif and become dislodged and project beyond the inner surface ofthe wall I0. This reduces the efficiency of the burner blocks I| andnecessitates replacement of the blocks which requires-shutting down the heating structure for making the necessary repairs.

In accordance with my invention, in order to increase the life of refractory'shapes, the blocks II and I2 are formed of refractory material of poor thermal conductivity -possessing the requisite thermal insulating properties, and tie rods 3| and 32 are embodied in each block to hold thelatter together when heat is concentrated at their inner `surfaces and stresses are induced in the blocks due to uneven heating of different regions thereof adjacent to and removed from the highly heated inner surfaces.

The tie rods 3| and 32 are preferably formed of refractory material of high tensile strength and provided with enlarged end portionsl as shown in Figs. 5 and 6. rIn the wall I0 the burner blocks II in the 'top and middle rows and all of the filler blocks I2 are provided with spaced apart recesses 33 at the top and bottom surfaces thereof to receive the tie rods 3|. The recesses 33 are deeper at the front and rear ends than at the intermediate portions, as shown in Figs. 2 and 3, to receive the enlarged ends 34 of the tie rods 3l. The tie rods 3| are snugly secured in position, as by cement, for example, so that the blocks II and I2 and the tie rods 3| embodied therein are provided with smooth outer surfaces to facilitate mounting the blocks in the wall III.

Tie rods 32 of the form shown in Fig. 6 are embodied in the burner blocks in the bottom row of the wall I0. 'I'he tie rods 32 are of cylindrical shape land formed with enlarged rounded ends 35. The tie rods 32 are secured in position, as by cement, for example, in recesses formed by complementary semi-circular grooves or passages at the abutting surfaces of the sections 25.

The tie rods 3| and 32 effectively hold each of the blocks and I2 together when the inner faces of the blocks are heated toa highly radiant...

condition and stresses are induced in the blocks due to the rear parts remaining relatively cool while the regions adjacent to and at the inner surfaces are heated to high temperatures.

Although the tensile strength of the refractory blocks and I2 in and of themselves may be insuflicient to withstand repeated thermal shock, the tie rods 3| and 32 of high tensile strength are capable of withstanding the thermal shock to which the blocks are subjected and tend to retard cracks developing in the blocks as well as to retard the growth of cracks after they once occur. Further, when the blocks and I2 are subjected to repeated thermal shock over a long interval ofvtime and the blocks may split, the tie rods 3| and 32 effectively hold each block together and prevent any part thereof being dislodged. Thus, in the event a part of a burner block breaks off at the vicinity of the radiator I4, the tie rods effectively hold such part in place whereby the effectiveness of the burner block will not be impaired.

It will be seen that the shoulders 36 formed at the inner parts of the enlarged ends of the tie rods, which bear against the ends of the intermediate raised portions of the slots, are lnclined or slanted and not square. However, such slanted or inclined shoulders 36 have been found satisfactory to grip the front and rear portions of' che msm n and n' wnefebytne mm may.

be maintained as unitary structures.- Y

By' way of illustration and without limitation I have'successfully employed tie rods formed practically entirely or preponderantly of silicon carbide in burner blocks il like those shown and described and formed of mullite. Buch burner blocks have been used-inheating apparatus in which the work is `relatively close tothe burner wall 'and'temperatures produced at the radiators '.l'hetie rods of silicon carbide effectively held each mullite block .together even though repeatcdli1 subjected to thermal shock.

While the thermal conductivity of tie rods formed of silicon carbide is greater than that of the porous ceramic material of which the refractory shapes may be formed, such as mullite, for example, the cross sectional areaof the tie rods collectively is relatively small compared to that 25 mal conductivity having a passage therethrough from a first face to a second opposite face andY a cavity at the rst face adapted to be heatedof the refractory shapes; and the fact that the tie rods may be slightly less effective-than the porous block material to keep the heat loss through the refractory wall at a minimum is more than compensated bythe'additional bene-,- fits gained whereby the inner faces of the shapes are anchored to the cooler rear portions thereof by material of high tensile strength.

Hence, in practicing the invention, the rear l portions of the refractory shapes may beanchored by the bolts 21 to the outer metallic reinforcing parts of the heating structure and the inner faces of the blocks Il and I2 are in turn anchored by the tie rods to the rear cooler portions of the blocks, whereby eifective anchoring of the entire wall may be accomplished from the outer metallic parts directly to the inner faces of the blocks which'form the inner refractory lining of a heating space.

Although several 'embodiments of the invention have beenshown and described, it will be apparentl to those skilled inthe art that vmodifications may be made without departing from the spirit and scope of the invention, as pointed out in the following claims.

What is claimed is:

1. A refractory article comprising a body of f refractory material of poor thermal conductivity ,f having a ilrst face thereof adapted to be subje'cted to a source of heat at an elevated temperature, said body vhaving a recess which extends from a region adjacent to the nrst face to a region adjacent to an opposite face thereof, vand a rigidl tie rod in the recess which is formed of refractory material of greater tensile strength than the first-mentioned refractory material, the recess and tie rod therein being formed and arrangedv to hold said body together when said first face is subjected to the heat source and stresses are induced in the body due to uneven heating thereof at regions adjacent thereto and removed from said first face.

' 2. A preformed refractory article comprising a block .of refractory material formed of two sections secured together and having a face thereof adapted to be subjected to a source of heat at an elevated temperature, said sections at their abutting surfaces having complementaryrecesses forming an opening which extends from a region adjacentto said face to a region adjacent to an opposite face of said body, and a rigid tie rod positioned in the opening which' is 'formed of refractory material of greater tensile strength than the first mentioned refractory material, the a tie rod forming a component part of the article and having enlarged end portions and an intermediate connecting portion of reduced cross-v l0 conductivity having an opening .therethrough from a ilrst face to a second opposite face and a cavity at theI ilrst face adaptedto be heated to a highly radiant condition by combustible fuel I mixture supplied through the passage, said body lli having a recess which extends from a region ad-` jacent to said first face to a region removed therefrom, and a rigid tie rod positioned .in the recess which is formed of refractory material. of higher tensile strength than the first-mentioned 20 refractorymaterial, the tie rod having enlarged end portions and an intermediate connecting portion of reduced cross sectional area.

4. A preformed refractory article comprisinga bodyv of porous ceramic material of poor ther- 30 tie rod embodied in the body which rod extends fromy a region adjacent to said tlrst face toward the second face, said tie rod being formed of.

refractory material including silicon carbide'having greater tensile strength than -the ceramic 35 lmaterial and having enlarged end portions and an intermediate connecting portion vOfreduced cross sectional area.

5. A burner block comprising a body of re'- fractory material of low thermal conductivi- 40 ty having opposed faces and opposed sides, said body being formed with a cavity in one face and a passage extending vfrom said cavity to the apps-'- site face thereof, said body also being formed with a recess on each of said opposedA sides, ex- .is tending from face to face, and a heat resisting vrefractory tie rod received in each of said rcesses, ysaid tie rods acting to reinforce the facesof said block.

6. A burnell block according to' claim 5 in so' whichsaid recesses have enlarged ends adjacent..

said faces, `and enlarged ends on said tie rods received inthe enlarged ends o f said recesses'.

`'1.' A burner block vcomprising a body of refractory material formed with opposed faces anda ss burner cavity in one face, a recess formed in said body and extending between said faces and a tierod Aof heat resisting refractory extending be- J v Atween said faces and completely received by said recess and forming an integral portion of said so body, saidl tie rod serving to reinforce the faces of said body.

8. A refractory article comprising a block of refractory material having low heat conductivity, said block being provided with a pair of opposed as faces oneoff which is to. be subjected to a source 'of heatat an elevated temperature, and sides 'extending between said faces, one of said sides being provided with a recess extending from face toface of said article, and a rigid refracto-ry in- 10 sert received in said recess, said insert being 15 recess is deeper at said faces than at the region between said faces and said insert is provided with enlarged portions received by said recesses.

10. The combination of claim 8 in which said article is mullite and said insert is silicon carbide.

1l. A burner block of refractory material having low heat conductivity, said block havingl opposed faces and sides joining said faces, one face being adapted to be subjected to high temperature whereby internal stresses are set up in said block tending to crack the same, said sides being provided with recesses extending from one face to the other, and an insert of refractory material having high tensile strength at said temperature received in each of said recesses and serving to reinforce said block to prevent cracking of the same.

EMIL BLAHA.

REFERENCES CITED The following references are of record in the file of this patent:

8 UNITED STATES PATENTS Name Date Smith -v Aug. 12, 1879 Laird Jan. 20, 1920 Cannon Mar. 15, 1921 Apr. 24, 1923 Grimths Aug. 19, 1924 Parker: Feb. 16, 1926 Jacknan Apr. 16, 1929 Haniman Apr. 23, 1929 Gilbert Nov. 19, 1929 Brown Apr. 15, 1930 Soper June 7, 1932 Hartland June 7, 1932 Nichols Nov. 19, 1935 Moriock July 26, 1,938 Hess Sept. 17, 1940 Doyle Dec. 24, 1940 Hess June 23, 1942 Marchant Sept. 22, 1942

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