US2532112A - Checker for furnaces - Google Patents

Description

Nov. 28, 1950 F. AH. MACKENSEN CHECKERy FOR FURNACES Filed Dec. 16, 1944 2 Sheets-Sheet l Nov. 28, 1950 F. H. MAcKENsEN CHECKER FOR FURNACES 2 Sheet-s-Sheet 2 Filed Dec. 16, 1944 Patented Nov. 28, 1950 lCI-IECKER, FOR FURNACES Fred. H. Mackensen, Bettendorf, Iowa, assignor to Mexico Refractories Company, Mexico, Mo., a corporation of Missouri Application December 16, 1944, Serial No. 568,431

6 Claims. l

The present invention relates to high temperature furnace construction and particularly to the regenerating chambers of heating furnaces wherein a checker arrangement of heat absorbing units is made for the purpose of utilizing the heat of the Waste gases as they pass from the heating chamber to the stack or chimney. Such devices have been the subject matter of considerable development as witnessed by the following Letters Patent; Bigelow No, 1,916,458, McKelby No. 2,107,675, Milner No. 2,257,392, wherein the structural features of the checker chamber are stressed. In other Letters Patent such as No. 2,108,871 and No. 2,303,741 stress is placed upon the cleaning of checkers.

It is the purpose of my invention to provide a new type of checker unit whereby the checker construction is practically self-cleaning so that it is not necessary to clean or disturb the checkers during a campaign in order to maintain their efficiency at a high level.

It is a further purpose of my invention to pro vide individual checker units of such a nature that they can be arranged in piers in the checker chamber in such relation to each other as to disperse the air and gas to all parts of the chamber thus obtaining uniform temperatures and providing more heating area per cubic foot of chamber volume. The particular layout of the piers 0f checker units will, of course, vary because of the great variety of diferent designs of furnaces and sizes of chambers. However, the fundamental design of the refractory units which comprise the checker elements that make up the piers, makes it possible to individually vary the construction without varying the individual design of the checker unit and without losing any of the advantages thereof.

The nature and advantages of my invention will appear more fully from the following description and the accompanying drawings wherein a preferred form of the invention is shown. It is to be understood however, that the drawings and description are illustrative only and are not to be taken as limiting the invention, except insofar as it is limited by the claims.

In the drawings:

Figure 1 is a vertical sectional View transversely through a portion of a check chamber in a regenerator open hearth furnace;

Or' or) Figure 2 is a sectional view taken at right angles to Figure 1;

Figure 3 is a longitudinal sectional View through a preferred form of checker unit employed in accordance with my invention;

Figure 4 is a plan View of the unit;

Figure 5 is a longitudinal sectional view through a top unit employed in. building the piers of checker units;

Figure 6 is a plan view of a slightly different form of checker unit wherein the unitpis made up of segments;

Figure 7 is a view in side elevation of the checker unit shown in Figure 6; and

Figure 8 is a plan view of one of the segments of the unit shown in Figure 6.

In checker chambers of regenerator furnaces, the waste gases are circulated from the heating chamber in one direction to heat the refractory elements in the checker chamber for a certain length of time, and then the air flow is reversed so that heated refractories give up their heat to the air going into the heatingV chamber, This means that waste gases may carry with them particles in suspension, condensable vapors and even large particles so that the horizontally extending surfaces in the checker chamber, and any surfaces in the checker chamber that form substantial pockets with a supporting surface more nearly horizontal or as nearly horizontal as the angle of repose of the particles, will collect the particles.

According to my invention I propose to provide a checker brick which, because of its shape, I refer to as an hour glass unit. In the drawings a unit of this character is shown in cross section at I0, Figure 3. Both ends Hand I2 of the unit are larger in internal and external diameter than the mid portion I3 of the unit. The unit is made of a suitable refractory material for use in open hearth furnace checker chambers. This unit has iiat top and bottom surfaces which are substantially parallel to each other so that several of the units I0 may be stacked one upon the other in the manner shown in Figure l of the draw-y furnaces there is a direct passage upward through the roof l 5 and horizontally to the heating chamber. There is usually a supporting means in. the

tiplicity of channels in the checker chamber,h i5

some of the channels being inside the units and other channels being between the units: The

piers may be spaced and staggered in anyfsuitf.- able form to provide for thebest distributienet;

the air channels in the checker chamber It is immaterial Whether the gas passing through the chamber is going up or down,insofarasobtain-` ing a thorough contact of the gas with there.- fractory checker units is.`- concerned. The particular hour. glassshape oftheindividual checker units provides alternate surfaces vertically through. the checkerchamber againstlwhich the gas. isA directed..` Inside-the piers. there are altornate' restrictions and expansions in cross section of the passages. This islikewise true outside" thepiersbutythe restrictions are at Ythe level where the greatest Vcross section insidethe piers.

exists. The angle made by the surfaces of; the checker-.units ill with a horizontal line ismuch greater than the 4angle of repose for any particles that are carried over from the heating chamber. If. vapors. condense and form deposits, the air circulation around Ythe piers and through'the piers tends to remove any accumulation of material at a particular point on a unit.- The sev-- eral checker units stacked one upon theother mayggof, course, be cemented together as desired. Units are'molded quite smooth and are. matched carefully in mounting one on top the other so as to leave no ledges projecting to invite `the accu-..

mulation of Aforeign particles. Referring. now to Figure 5 of the drawings, this yngure illustrates a top checker unit lila. This checkerunit is essentially the same as that shown in Figures 3 and. 4 of thedrawings` :except that Vit has itsupper* edge .I9 tapered .as shown so as to prevent. the.

accumulation of particles at .the top Vedgeof the unit;

Itmay be desirable from'a molding standpointV to'make the checker units in more than one piece. Figures 6, 7 and 8 illustrate a checker unit/which is made up of four pieces. 20'is'shown in Figure 8 asv being semicircular in cross-section and tapering from 'one end to the other'so asto provide surfaces 2l. and22' ofthe rightr contour, VFour cithese pieces 28' are then cemented together or otherwise connected so that th'eyprovidea complete unit 23 wherein the joints 24 between horizontal adjacent units are staggered circumferentiallycof rthe assembly. The'. Vertical faces of'the units 2t are of' such AshapeV that they can be provided'with tongue and grooved .elements'to facilitate'uniting. the indi' vidual pieces 20 into a 'complete'checker'unity I iindthat a checker chamber constructed with I piers made with the checker unit disclosed herein has thedistinct advantage that itis self-cleaning.

so' that it is not necessary to cleanI the checker unit during a campaign, Since there is no cleaning done, I haveno difficulty with'the checker An individual piece' iii) units being pushed out of place or falling. The whole construction of the checker unit provides for a high efficiency of the refractories since I obtain a maximum heating area per cubic foot of chamber volume. For example, I can provide an effective heating surface of approximately three square feet of heat for each cubic foot of chamber volume.

It is believed that the foregoing description will enable those skilled in this art to understand and practice the invention disclosed herein. Having thus described myjnvention, I claim:

1. A checker installation for regenerative furnaces comprising a supporting structure, and

#hollow annular piers of refractory material resting on said structure and spaced from each other and open at both ends, thereby providing air passages. through thepiers and between them, the piers comprising sections increasing in cross sec- :tional' area. alternated with sections decreasing in cross sectional area, the surfaces where the directions change being curved in the direction corresponding to the length of the piers.

2. A checker installation for regenerative furnaces comprising a supporting structure, and hollow annular piers of refractory material'resting on said vstructure and spaced from each' other. and open at. both ends, thereby providing air passagesthrough the piers and .between"them;. the piers comprising sections increasingincross'. sectional area alternated with'sections` decreasing in cross sectional area, Vthe slope' of Ythe surfaces in both sectionsbeingso small asV substantially: to `prevent accumulation of fine particles. carried by-waste gases into said air. passages, the surfaces.. where the directions change being curvedv in theA direction corresponding to the length ofthe piers;

3. A checkerinstallation for regenerativefur: naces comprising a. supporting structure; and hollow annular piersof refractory material 'rest'- ingon said structure and spaced from each other and open atboth ends, thereby providing air pas-r sages through the piers and between them; the; pierscomprising sections increasing in crosssec` V tional area alternated with sections decreasing in cross sectional area, the `slope .of .the sur# faces in both sections being so small as substantially to prevent accumulation of iine particles carl-1 ried. by waste gases into said' air passages, 'the top and bottom ends of said piers being at the points of. greatest cross sectional area,.the surf: faces Where the directions change-being curved; in the direction corresponding to.. the length of'. the piers,

4. A checker unit of refractoryv material come; prising a hollow body'vwith its opposite endsisub-' stantially equalin shape and size so that units.' may be stacked, said body gradually.. decreasing in cross section from .its ends toward the center;y said bodybeing composed of a pair of.likesec-V tions tapering from .end to end,` the small'ends` of the two sections being joined..

5..A checker unit of .refractory material com; prising a hollow bodyiwith itsopposite ends'substantially Aequal in. shape and size so that units'. maybe stacked, said body `gradually decreasing in cross sectionv from .itsends toward the centen.v said. body'being composed of a .pair of like. seca tions tapering from end. to end,.th`e small lends; of the two sections beingjoinedgsaid sections each comprising two semiannular like pieces, joined together, the longitudinal jointsA between pieces of' one section being. staggered .withi`re-i spect to longitudinal joints in the adjacent.sec... tions.

2, 532, 1 1 2 5 6. A checker unit of refractory material for the REFERENCES CITED top of a pier of a regenerative furnace comprising The following references are of record in the a hollow circular body having its major portions me of this patent: substantially symmetrical about is vertical and horizontal axes, said body gradually decreasing 5 UNITED STATES PATENTS in cross section from its ends to its center, the Number Name Date bottom face of said body being flat to permit 1,897,270 Mitchell Feb. 14, 1933 stacking on the top of a column, the upper edge 1,951,579 Pohl et al Mar. 20, 1934 of said body being tapered to an edge to prevent 2,107,675 McKelvey Feb. 8, 1938 a-,imulatlon of particles at the top edge of sald w FOREIGN PATENTS FRED H, MACKENSEN, Number Country Date 242,083 Great Britain Nov. 2, 1925 445,045 Great Britain Apr. 3, 1936

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