US2900965A - Insulated boiler wall - Google Patents

Description

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ERNEST C. WITZKE c. WITZKE INSULATED BOILER WALL I 24 .Lf-III Aug. 25, 1959 Filed Sept. 16, 1953 WIUMAUIM.

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Aug. 25, 1959 E. c. WITZKE INSULATED BOILER WALL Filed Sept. 16. 1953 2 sheets-sheet 2 ixmw m\\ w@ INVENTOR. ERNEST C. WITZKE BY MSW United States Patent O M INSULATED BOILER WALL Ernest C. Witzke, Bayside, N.Y., assigner to Combustion Engineering, Inc., New York, N.Y., a corporation of Delaware Application September 16, 1953, Serial N0. 380,486

1 Claim. (Cl. 122-6) This invention relates to walls for boilers or ducts through which high temperature gases are conveyed and has particular relation to such Walls wherein a cement coating forms one of the wall surfaces.

In boiler walls and the like wherein insulating material is interposed between the inner and outer surfaces of the wall there is necessarily appreciable relative movement between these wall surfaces resulting from differential expansion caused by the very large temperature differences that are attained between the surfaces. Because of this relative movement it has heretofore been virtually impossible to prevent cracking of the cement coating which is applied to the wall and forms one of its surfaces and which is necessarily integrated with the other layers of the wall to integrally bind the wall structure together.

With the present invention this cracking of the cement coating is completely eliminated and a coating which is substantially uid `tight and remains structurally sound is provided.

Generally stated the invention comprises an insulated wall one of the surfaces of which is lined with a suitable metallic means which may take the form of boiler tubes or the metal sheeting commonly used in duct work. A cement coating or layer forms the other surface of the wall and intermediate these surfaces is interposed suitable insulating material. The layers of the wall are bound together and held in operative relation by means of suitable wire connectors or other suitable means which extend from the metallic means to the cement coating and are connected to these elements thereby suspending the entire wall from the metallic means. The cement coating is formed of polygonal panels (disclosed as rectangular) which are reinforced with expanded metal. Adjacent panels are spaced suiciently to accommodate the necessary relative movement between the panels and expansion screeds, in the form of flexible metallic strips, are positioned intermediate the edges of said adjacent panels with each strip extending throughout the length of the adjacent edge of one pair of panels and secured thereto in a liuid tight manner. These screeds are provided with a longitudinally offset portion which exes in response to relative movement between adjacent panels thereby accommodating this movement without disturbing the connection of the strip with these panels. Each of the reinforced cement panels has imbedded in the cement a pair of base screeds, also in the form of flexible metallic strips with the strips extending across the panels in a manner to divide the panels into quarters. These strips are also provided with a longitudinally extending offset portion which is effective to accommodate shrinkage of the cement after it has been initially applied.

It is the object of this invention to provide an insulated layered wall with an improved cement coating which will not be adversely affected by relative movement between layers of the wall or shrinkage of the cement.

Other andfurther objects of the invention will become '2,900,965 Patented Aug. 25, 1959 ICC apparent to those skilled in the art as the description proceeds. j

With the aforementioned objects in View, the invention comprises an arrangement, construction and combination of the elements of the wall organization in such a manner as to attain the results desired as hereinafter more particularly set forth in the following detailed description of an illustrative embodiment, said embodiment being shown by the accompanying drawing wherein:

Figure 1 is a fragmentary elevational View of a wall embodying the present invention;

Figure 2 is a sectional view taken along line 2--2 of Figure l showing to an enlarged scale the detailed construction of the wall;

Figure 3 is a view similar to that of Figure 2 but showing the wall in its expanded or hot position;

Figure 4 is an enlarged View of the expansion joint screed disclosed in Figures 2 and 3 and. showing more clearly the details thereof;

Figure 5 is a similarly enlarged view of the base screed of Figures 2 and 3;

Figure 6 is a view similar to that of Figure 3 but showing a modified form of expansion joint screed;

Figure 7 is a View generally similar to that of Figure 3 but showing a modified form of wall such as used in gas ducts wherein one of the surfaces is formed of metal sheeting;

Figure 8 is an enlarged fragmentary view showing the juncture of the expansion joint screeds at the corner of the panels shown in Figure 1;

Figure 9 is a sectional view taken along line 9 9 of Figure 8;

Figure 10 is a perspective View of the seal box that is employed at the juncture of the screeds.

Referring now to the drawings, wherein like reference characters are used throughout to designate like elements, the wall depicted in Figures 1, 2 and 3 is the wall of a modern boiler having its inner surface lined with metallic heat exchange tubes 10 and its outer surface provided with a coating or layer of cement 11. Intermediate these surfaces is provided a layer of refractory 14 which is in engagement with the backs of the tubes and which isspaced from cement coating 11 by the two rows of insulating blocks 16. The cement coating 1i is reinforced by expanded metal 1S and the entire wall structure is secured together by wire elements 20 which are connected to the laterally extending studs 22 provided on various of the tubes 10 and extend through the refractory i4 and the insulating blocks 16 to the cement coating 11 where they are interconnected with the reinforcing Il@ of the coating. The wire elements thus bind the layers of the wall together and suspend the entire Wall from tube elements 10.

In order to prevent cracking of the cement coa-ting 11 this coating is fabricated of independent rectangular panels which are placed in side-by-side relation with adjacent panels being slightly spaced. rTwo complete panels are shown in Figure 1 and are identified as 23, the triple lines indicating the boundary of each panel. Positioned within the space between adjacent panels are flexible metallic strips or screeds 24 each of which eX- tends throughout the length of one pair of 4adjacent panels. These screeds are provided with laterally extending anges 26 which are sealed to the adjacent cement panels and are secured to the reinforcing 18 of these panels by wires 28 or the like as best shown in Figure 4.

Intermediate these flanges 26 the screeds are formed with `movement between the adjacent panels to which the Yscreed is secured.

In addition to the expansion screeds 24, which are placed intermediate and are interconnected with the adjacent panels 23 to accommodate relative movement between these panels, each of the panels yhas a pair of base screeds 34 imbedded in the cement thereof and extending Iacross the panel in a manner to divide the panel into four quarters as disclosed in Figure l, the double lines indicating the base screeds in this figure. Each of the base screeds 34 comprises a strip ofmetal secured to the reinforcing 13 by wire elements 35 or the like and having 'a longitudinally extending offset portion extending toward the outer surface of the wall with the extremity thereof even with the outer `surface of cement coating 11. These base screeds are effective to accommodate the shrinking of the cement after it is applied without the production of cracks lwhich usually .result from such shrinkage.

In fabricating the wall `of this ,invention after the layer of refractory 14 has been positioned at the back of tubes and insulating blocks 16 have been put in place with wire elements 20 extending therethrough from studs 22, the expanded metal reinforcing 18 in panels corresponding to panels 23, is connected to the outer ends of these Wire elements and the expansion screeds 24 and base screeds 34 are wired to this reinforcing with the expansion screeds being positioned in between the edges of the separate reinforcing for each panel while the base screeds are placed over and extend across each such separate reinforcing. The cement is then applied over this reinforcing with offset portion 36 of the base screeds 34 and offset portions 30 of the expansion screeds 24 functioning as guides for obtaining the proper depth or thickness of the cement coating. After being applied the cement in drying shrinks or contracts somewhat and as mentioned hereinbefore it is the purpose of the base screeds 24 to accommodate this shrinkage within each individual panel 23 without producing cracks in the cement surface.

In the embodiment of Figs. 2 and 3 the offset portion 32 of expansion screeds 24 is considerably larger than the two offset portions 30 and therefore will flex to accommodate relative movement between the adjacent panels to which the screed is connected with offset portions 30 principally functioning as guides in applying the cement coating. In this form of the invention offset portions 32 extend inwardly from the walls outer surface into a suitable space provided in the outer layer of insulating blocks 16. In Fig. 2 the Wall is shown in the cold or contracted position where all of the layers of the wall are at substantially the same temperature while -in Fig. 3 the Wall is shown in the expanded position Where heat exchange tubes 10 are extremely hot while cement coating 11 is relatively cool. As will be seen in comparing Figs. 2 and 3 when the tubes 10 become heated they expand relative to the outer layers of the Wall and since the walls layers are bound together by wire elements 20 these .outer layers are to a certain extent carried along with the expanding tubes 10 thereby resulting in the insulating blocks 16 and the cement panels 23 moving apart as Shown in Fig. 3. During this expansion movement the Wire elements 20 that are connected to panels 23 adjacent the outer edges of the panels will necessarily be displaced slightly within the cement of the panel. This cement remains sufficiently plastic however, to permit this slight displacement Without cracking. Since each of the expansion screeds 24 extends only throughout the length of but a single panel, at the corner of each panel four separate screeds come together to form a juncture. In order for this juncture to be fluid tight and thereby permit the entire cement coating to form a fluid tight barrier against the passage ofhot gases throughY the wall, seal box 37 is provided to effectively seal the ends of the four screeds relative to each other. This box has slots'39 formedin its four walls for the reception of offset portions32 of the 4 l `screeds and the interior of the seal box is lled with plastic insulation 41 which forms va uid tight seal while permitting flexing of the offset portions 32 encountered during expansion and contraction of the Wall.

The embodiment of Fig. 6 is similar to that of Figs. 2 and 3 except that in this embodiment the expansion screeds, designated 43, areV provided with a single longitudinally extending offset portion 45 for accommodating relative movement between adjacent panels 23. These longitudinally extending offset portions extend outwardly of the wall and project beyond the outer surface of. cement coating 11. These screeds eliminate the V-shaped `opening formed by the embodiment of Figs. 2 and 3 which in certain positions may be subject to becoming filled with foreign matter.

While Figs. 2, 3 and 6 disclose the invention as applied to a boiler wall it is of course equally applicable to other types of walls as, for example, the walls of gas ducts through which high temperature gases are conveyed and a section which is represented in Fig. 7'. The wall of this ligure is generally similar to that of Figs. 2 and 3 except that sheet metal duct work 47 has replaced the heat exchange tubes and refractory shown in these figures. Fig. 7 represents the Wall of a duct wherein sheet metal 47 forms the inner surface of the duct and thus will he` come hot and expand while the cement coating 11 will remain relatively cool and unexpanded. In such rcase panels 23 will move apart increasing the spacing therebetween as the sheet metal expands. It will beunderstood, however, that cement coating 11 may equally well form the inner surface of the duct while sheet metal 47 forms the ducts outer surface. In this case the cement coat ing will have a much higher temperature than the sheet metal and will accordingly expand relative thereto. This will cause adjacent panels 23 to move toward instead of away from one another relative to their so-called cold position and therefore in such case the original spacing of the panels will have to be relatively large to accommodate this movement.

In fabricating the wall of this invention it has been found convenient for ease of handling as well as other considerations to make the panels square with a dimension of 8 ft. per side. This results in a wall in which the cement coating remains free of cracks caused by thermal expansion as well as shrinkage of the cement after `being applied and since this coating is, for all practical purposes, fluid tight, gas leakage through the wall together with the consequential lire hazard thereof is eliminated.

While I have illustrated and described a preferred embodiment of my novel wall organization Vit is to be understood that such is merely illustrative and not restrictive and that variations and modifications may be made there in without departing from the spirit and scope ofthe invention. I therefore do not wish to be limited to the precise details set forth but desire vto 4avail myself of such changes as fall within the purview of my invention.

What I claim is:

An insulated wall having metallic tubes lining one of its surfaces and a coating of cement forming itsV other surface with a plurality of layers of relatively movable,

insulating blocks interposed between the two, exible wire means extending from the metallic tubes through the insulating blocks to the cement coating and integrallybindcement panels having expanded metal reinforcing embedded therewithin and extending uninterrupted throughout 4the area thereof with adjacent panels .having their edges parallel and slightly spaced and with adjacent 'edges of adjacent panels being coextensive and of equal length,

said wire means effectively interconnecting the tubes andY the reenforcing,exible metallic rstrips positioned intermediate said adjacent edges with each strip extending throughout the length of the `adjacent edges of one pair of panels and sealably secured thereto with structural means interconnecting the strips and reenforcing in the panels, said strips having a longitudinally extending offset portion intermediate their logitudinal edges, means sealing the juncture of the strips at the corner of the panels, said means comprising a container having a pliable lling therein, additional flexible metallic strips extending across each panel between each pair of opposite sides of the panel and in overlying relation with the outer surface of the reenforcement, said additional strips being provided with flexible longitudinally extending and outwardly projecting offset portions intermediate their longitudinal edges, said last named offset portions extending from the 15 2,656,902

reenforcement to the outer surface of the panel with the longitudinal edges of lthe strips being secured to the reenforcing.

References Cited in the iile of this patent UNITED STATES PATENTS 1,357,713 Lane Nov. 2, 1920 2,029,817 Fegles Feb. 4, 1936 2,063,309 Graef Dec. 8, 1936 2,272,762 Awbrey Feb. 20, 1942 2,315,833 Youker et al Apr. 6, 1943 2,370,052 Lindelow Feb. 20, 1945 2,536,039 Craven Ian. 2, 1951 Gotshall Oct. 27, 1953

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