US2648315A - Boiler furnace wall construction - Google Patents

Description

Aug. l1, 1953 w J. KuNz BOILER FURNACE WALL CONSTRUCTION 2 Sheets-Sheet 1 Filed Jan. 22, 1947 AA v Kunz

Aug 11, 1953 w. J. KuNz l2,648,315

BOILER FURNACE WALL CONSTRUCTION Filed Jan. 22, 194'? 2 Sheets-Sheet 2 Fig. Q 9 INVENTOR Willi J. K nz WM Patented Aug. 1.1K, 1953 UNITED STATES 4PATE-NT OFFICE William J. Kunz, vv"Port Washington, N. Y.,1assi'g`nor to Combustion Engineering, lne., a corporation of Delaware Application urinary 22, roimse'rilNo."#3344 4 Claims. l vThis Vinvention relates `to furnace Walls `:and'fin particular to furnace Walls Whose inner faces are lined with fluid-cooled tubes, as inthe furnaces .for steam generators.

A satisfactory construction of furnace walls-- Vfor a steam generator comprises 'an inner lining of fluid-cooled tubes which `are'exposed on their inner sides to the heat from the burning fuel and are covered on their outers'ides Withalayer of refractory material backed by Vva layer 'of in-" sulation and the Whole 1'Ii/al1 structure covered by a Asteel lcasing built 'sufficiently strong jto ire? sist furnace pressures. `Because of the cost "of this steel enclosed construction there have `'been increased requests for less expensive Walls "of 1" plastic construction. i

In general, the plastic walls as "heretoforefconstructed, are made in one homogeneous mass,

necessitating the expansion and contraction rof the entire Wall as a unit. Because of the variaf Figure 1 is a fragmentary elevation fof thejout- A yside of a furnace Wall embodying *my iimgiroved structure;

Figure 2 is an enlarged fragmentary'elevation of a typical panel shown in Figure 1;

Figure 3 is an enlarged section 'in elevation taken on line 3-3 of Figure 1*; and

Figure 4 is a section taken on line '1l-4 "of Figure 2.

The furnace Wallhere illustrated'lcomprisesla row or bank of vertical duid-cooled tubes lI linn ing the outside of the furnace. Thesetubsare exposed on their inner sides to Jthe heat*f ro'rn the burning fuel, the temperature'of `'combustion being generally Well over 2000 deg. F. -In s'tea'rn generators such furnace tubes are connectedjfor iiow of cooling fluid therethrough, into "Water circulation With the boiler`in aw'ell known inanner, The tubes lI may be arranged in'a'iowlli'n side by side relation as sho'y'vii'inthe"left`half of Figures 2 and 4 or they may 'be in spaced 'apart 'relation yas shown in the right half of said figures. -In vthe latter arrangement they are pref- 'erably provided with Welded -on `fins 2 which Ypr-oject into Vthe intertube space to substantially close the 'gap ibetween 'tu-bes. These Ifins 4absorb heat Awhich flows to 'the tubes land into the ywater therein. A

On the outer side of -the rowof tubes I there is provided an inner, -x'ne'tal -reinforced ls'lfab 3 of 'plastic refractory lin*after-iai, the reinforcingme'tal 4 being preferably 'an expanded met'al Ao'r fheavy wire mesh. This reinforced slab 3 extends continuously "over the "entire outside 'surfacefof 4the ytube Wall andis of substantially uniform thickness, forming va 'ijnono'lithic `=1ay`er lor backing to the tubes. uIncase thetubes I are larranged in side vby side relationas-shown on the 'left half `of 'Figure "4, 1the plastic of Slab3 `inay extend 'into lthe spaces between tubes. '--In case the tubes I are arranged 'in fspaced "apart relation as `shown yin 'the right half of Figure '4, the' intertube space 5 between the fins=2 andfthe plane tangent to-the vbacks of the tubes vis :preferably Vfilled in byv high 'heat resisting refractorylblocks shaped tot into the space or Aby "a plastic of `said refractory material.

yThe plastic l"slab j3 fis of substantial thickness and due to its reinforcement resists bending vas Well as cracking. The slab`3 will cooperate-with the remainingjwall structure, to 'be hereafter described, `in resisting and distributing the-pres- "sures vboth Linternal and external of the furnace yThe reinforcing v4, orzex'p'anded metal, is lspaced from the backs of the tubes vby vStuds 'f6 Whic'hare `Welded to Ythe tubes and Iei'itend rearwardly therefrom. '-The reinforcingis held inlplace and is supported bystudsfli as by nuts 'andwashers for other suitable fastening 'devices fl. IIn this manner the entire inner slab 13 is supported'by and securedl to the tube-bank I.

The inner-"slab "3 approaches the -ave'rageiternperature of the 'rearward portiony of the fluidlcooled steel tubes and ns. The lexpansion of vthe tubes I and the refractory 4material -3-1and the reinforcing steel t-arefsubstantially the saine for 'the -same v`range in temperature. Consequentlythe bank of "tubes'I andslab '3 expand together in directions parallel'v to the tube bank and any injuriousexpansion strains between the two to causecracks -are'thereb'y avoided.

Spaced vfrom and parallellt'o' theiinner -Wall slab 3 is an outer, 'metal 'reinforced slab'of plastic material and similarin construtiontoithe'inner slab 3. Preferably. expanded rnetalor heavy Wire 'mesh reinforcing '9 'is used. "This outer rreinforced slab 8 is supported from an outer structure of steelwork I independently of the tube bank and the inner slab 3. Intermediate the inner and outer slabs 3 and 8 is a layer of heat insulating material II which preferably comprises 'a multiplicity of rectangular blocks placed side by side to ll the entire inter slab space.

The outer steel structure I9 of the illustrated example, comprises horizontally spaced, vertical bars I2 which are suspended in a well known manner from steel beams (not shown). At spaced vertical intervals along the length of bars I2 are horizontal buckstays I3 extending across the width of the furnace wall and fastened, at the corners of the furnace, to the corresponding buckstays of the adjacent walls to form a wall stiffening, girth member around the furnace which maintains the alignment of all wall members and is capable of resisting any outward pressure exerted by possible internal explosion.

The buckstays I3 or channels are fastened to the bars I2 as by angle clips I4. To each buckstay I3 is fastened, such as by welding 30, a girth plate I5 extending flush within the outer surface of the outer slab 8. The sheets of expanded metal reinforcing 9 of the outer slab 8 extend partly across the back of girth plate I5 from above and below and are clamped thereto for support by a multiplicity of small plates I6 which are placed on the inner sides of the reinforcing 9 and held to the girth plate I5 by bolts I1.

Intermediate the buckstays I3 and between bars I2, are a multiplicity of vertically spaced, horizontal stiffeners I8 fastened at their ends to vertical bars I2 as by clips I9 and bolts 20. Fastened to the inside of each stiffener I8 are plates 2| which lie within the outer slab 8 and to which the reinforcing 9 of the outer slab is fastened as by wires passing through holes 22. In this manner the entire outer slab 8 is supported and stiifened by the outer steel structure I0.

The girth plates I5 of buckstays I3 have `angle clips 23 fastened to their inner sides at horizontally spaced intervals (Figures 2 and 3). One leg of the clips 23 extends inwardly to act as a support for blocks of-heat insulation II between the inner and outer slabs 3 and 8.

To maintain 4a fixed spaced relation between the inner and outer slabs 3 and 8, each girth plate I5 is provided with a multiplicity of horizontally spaced, spacing means. In the illustrated form, each spacing means comprises a spacing bolt 24 rigidly fastened to girth plate I5 as by nuts 25 and extending inwardly with its head adjacent the outer side of the furnace tubes I. A vertically slotted channel member 26 is fastened, as by Welding, to a furnace tube I, located with its slot straddling the spacing bolt 24 and spaced from the tube to allow the head of the bolt to freely move between the slot and tube. The width of the slot is greater than the diameter of the spacing bolt 24 to allow for some relative horizontal as Well as vertical movement, and a washer 2l prevents the bolt head from passing through the slot. The spacing bolts 24 are adjusted by means of nuts 25 to snugly contain the insulation II between the inner and outer slabs 3 and B. The spacing means described above is similar to that shown in the U. S. patent to W. J. Kunz et al. No. 2,223,215, issued November 26, 1940, and also serves to hold the furnace tubes in spaced alignment with the furnace steelwork I0.

In operation, wheen fuel is being burned within the furnace, the inner slab 3 approaches the average temperature of the rearward portion of the tubes and fins and the entire structure including the tube bank and slab expand together without injurious expansion strains which may cause cracks. The outer slab 8 approaches the temperature of the boiler room and its movement due to expansion is entirely independent of that of the inner slab 3. The outer surface of the inner slab 3 and the inner surface of the outer slab 8 constitute substantially parallel planes between which is held the insulation I I. The outer surface of the inner slab 3 that adjoins the insulation II provides a plane along which relative movements occur due to different expansions of the inner slab and the outer slab with respect to the installation.

Obviously if desired, the inner reinforced plastic slab 3 may be used in combination with an outer steel casing structure in place of the outer reinforced slab 8 as described.

While the preferred embodiment of my invention has been shown and described, it will be understood that changes in construction, combination and arrangement of parts may be made without departing from the spirit and scope of the invention as claimed.

What I claim is:

1. In la furnace wall, the combination of fluidcooled tubes disposed along the walls inner face in heat receiving relation to the furnace combustion chamber; an inner monolithic slab of plastic refractory material positioned against the backs of said tubes and having expansion characteristics which substantally match those of said tubes over the range of temperatures encountered during furnace operation; mesh-like reinforcing metal incorporated into said slab; stud bolts welded to the backs of said tubes and extending into the slab and cooperating with said reinforcing metal to secure said inner slab to the tube backs and to support said slab from said tubes for expansion and contraction together therewith; an outer slab of plastic refractory material positioned substantially parallel to said inner slab in spaced relation thereto and having reinforcing metal incorporated therein; said outer slab also comprising a layer of heat insulating material lling the aforesaid space between the inner and outer plastic slabs and serving to separate same in a way which permits relative movement between the slabs along the inner slab surface that adjoins the insulating layer and which latter causes the outer plastic slab temperature to be substantially independent of the inner slab temperature; an external structure for holding said outer plastic slab in its aforesaid position and for stiifening said entire wall against movement outwardly from the furnace center, said structure comprising spaced buckstay, stiffening and supporting members disposed adjacent the outer slabs exterior surface; and means cooperating with the outer slabs reinforcing metal and with the heat insulating material, for supporting said insulating material from the aforesaid external structure and for fastening said outer slab to the said external structure so as to provide for outer plastic slab stiffening and support which is independent of the earlier described support derived by said inner plastic slab from the furnace tubes whereby each of the aforesaid inner and outer slabs is permitted to expand and contract independently of the other without transmission of resultant movements therebetween or inducement in either slab of injurious mechanical stresses due to temperature differentials encountered during furnace operation.

2. A furnace wall comprising a layer of parallel side by side tubes making up the inner surface thereof, a reinforced plastic refractory slab supported from and positioned against the back of these tubes and having expansion characteristics substantially matching those of the tubes, a second reinforced plastic slab spaced outwardly of the first mentioned slab, heat insulation disposed in the space between the two slabs, outer support structure supported independently of the tubes and secured to the reinforcing of the outer slab thereby supporting the same independently of the tubes, and means effectively secured to the outer support structure and associated with said heat insulation for supporting the same from said structure.

3. A furnace wall comprising a plurality of parallel tubes arranged in side by side relation and making up the inner face of said wall; an inner slab of plastic refractory material having expansion characteristics the same as those of the tubes and having reinforcing Wire mesh embedded therein; studs disposed between certain of said tubes and said reinforcing means and secured to both thereby supporting said inner plastic slab from said tubes whereby the two move in unison; an outer plastic slab lying parallel to and spaced outwardly from said inner slab and having reinforcing wire mesh, embedded therein; steel stiffening and support members positioned adjacent the outer surface of the outer slab and supported independently of said tubes, said members including bars disposed parallel to said tubes and buckstays disposed transversely of said tubes, said bars and buckstays being effectively secured to the reinforcing in said outer slab thereby supporting said outer slab; means effective to maintain the spacing between the tubes and the outer slab substantially constant while permitting limited relative movement; a rigid insulating material disposed within and lling the space between said slabs; and means effectively secured to said buckstays for supporting said insulating material whereby it moves in unison with the outer slab and steel support members.

4. A furnace wall as defined by claim 3 wherein the buckstays are provided with girth plates disposed in the plane of the other plastic slab and to which the reinforcement in said slab is secured, and wherein the means for supporting the insulating material disposed in the space between the slabs comprises angular members secured to said girth plate and projecting into said insulation.

WILLIAM J. KUNZ.

References Cited in the le of this patent UNITED STATES PATENTS FOREIGN PATENTS Country Date Great Britain June 11, 1935 Number Number

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