US2889698A

US2889698A - Insulated furnace wall

Info

Publication number: US2889698A
Application number: US239058A
Authority: US
Inventors: William D Stevens
Original assignee: Babcock and Wilcox Co
Current assignee: Babcock and Wilcox Co
Priority date: 1951-07-28
Filing date: 1951-07-28
Publication date: 1959-06-09
Anticipated expiration: 1976-06-09

Description

June 9, 1959 w. D. STEVENS INSULATED FURNACE WALL Filed July 28, 1951 a 5 74 F|G.-2

INVENTOR FIG.1

William, D Stevens TTQRNEY BY A United States atent INSULATED FURNACE WALL William D. Stevens, Hackensack, NJ., assignor to The Babcock & Wilcox Company, Rockleigh, NJ., a corporation of New Jersey Application July 28, 1951, Serial No. 239,058

2 Claims. (Cl. 72--16) The present invention relates in general to walls enclosing hot gas chambers and passages and more particularly to a fluid heater furnace wall in which heat insulating materials are applied in successive layers and reinforcement is provided for a layer adjacent the exterior which may develop as a result of operating conditions so as to cause them to occur mainly at predetermined locations.

The various features of novelty which characterize my invention are pointed out with particularity in the claims annexed to and forming a part of this specification. For a better understanding of the invention, its operating advantages and specific objects attained by its use, reference should be had to the accompanying drawings and descriptive matter in which I have illustrated and described a preferred embodiment of my invention.

Of the drawings:

Fig. l is a fragmentary three-dimensional view illustrating a heat insulated furnace wall constructed in accordance with my invention, and Fig. 2 is a plan section of Fig. l as viewed in a plane at right angles to the wall cooling tubes.

In more detail, the illustrative embodiment of the invention comprises a wall in which fluid conducting tubes 3 are arranged in a row adjacent the inner face of the wall and thus along a surface which is exposed to internal furnace temperature conditions. Tubes 3 are normally held in alignment throughout the row, suitably by known means not shown. A layer of firebrick 4 is installed exteriorly of the row of tubes 3 and in contact therewith. Whereas the tubes 3 are shown in contacting relationship throughout the row, it is to be understood that successive tubes may be arranged with spaces therebetween in which case the firebrick also serves as a closure for such spaces. Studs 5 are secured at their inner ends to selected tubes 3 at spaced intervals throughout theheight and width of the wall. Suitably, the studs 5 are arranged at regular intervals in vertical and horizontal rows, with each stud secured to a tube by means of a weld.

Each stud 5 is preferably threaded so as to receive a plate nut 8 which is assembled thereon in contact with the firebrick layer 4. Exteriorly of the layer of firebrick, a block insulation 10 of considerable thickness is installed and, in the form disclosed, is retained in position by an additional set of plate nuts 9. The block insulation is a commercial product obtainable in fiat blocks of various standard widths and lengths. In composition, the block insulation herein described may, for example, be formed of a high temperature diatomaceous earth to provide desirably high temperature resistance and furthermore to afford structural stability. As a further example, a similar block insulation having a mineral wool base may be utilized.

At the outer side of insulation 10, the entire wall area is covered by a single layer of flattened expanded metal lath 12 which provides an overall pattern of diamondshaped openings 13 each of approximately one-and-onehalf inches in length. The metal lath is commercially available in sheets measuring 4 ft. x 8 ft. and, for the purpose of this disclosure, may be of a form identified as expanded metal lath, 1% inches x 13 BWG. In a wall as shown, the metal latch 12 is installed in full sized sheets, to the extent that this may be possible, and suitably with the longer dimension of each sheet and of each opening 13 extending vertically. Certain openings 13 are enlarged, if necessary, or slightly distorted so as to permit the studs 5 to extend through the lath without binding. I

Edge portions of adjoining sheets are overlapped, as shown in Fig. 2, so as to provide overlapping joints 14 of two inches minimum width throughout the perimeters of the respective metal lath sheets. In providing a joint 14 between adjoining sheets, the marginal portions of at least one sheet will become slightly distorted or bent out of the plane of the sheets as diagrammatically indicated in Fig. 2. However, the actual distortion is so small that preforming of the marginal portions is generally unnecessary. At intervals of approximately twelve inches along each joint, the contacting sheets of lath are fastened together by suitable means, not shown. An additional plate nut 15 is mounted on each stud 5 and tightened into contact with metal lath 12 so as to firmly clamp the lath in place between the inner and

outer plate nuts

9 and 15 at intervals throughout the sheets. All

plate nuts

8, 9 and 15 are suitably of equal dimensions, about 2 inches square.

A plastic insulation 16 of suitable known composition, such as a mineral wool insulating cement, is next applied to the entire metal lath-covered area of the wall to a depth sufiicient to completely bury the lath 12 and to fill all interstices between and beneath the strands of the lath while providing an additional uninterrupted thickness of about A" to beyond the outermost surfaces at joints 14, the total required depth or thickness of the insulating layer 16 being about to l" as measured from the face of block insulation 10. The insulation 16 is then grooved into panels by forming a groove 17 along each vertical and horizontal joint 14, preferably on a line with the outwardly disposed edge 18 of the outer overlapping lath portion. The panels thus formed correspond in size to the size of the underlying metal lath sheets. If smaller panels are preferred, for neater appearance, for example, a supplementary groove 19, or more than one such groove, may be formed on a line, or lines, intermediate the longer dimension of the metal lath so as to provide panels proportionately smaller in size than the originally formed full-sized panels. After all grooving has been completed, the layer of plastic insulation 16 is allowed to dry thoroughly and thereby harden into a tough but non-elastic layer in which fissures or cracks may develop as a result of subsequent temperature variations.

The purpose of forming grooves 17 directly over the joints between adjoining metal lath sheets or sections is to concentrate cracking of the hardened insulating layer 16 in lines along which cracking is most likely to be initiated as a result of repeated expansion and contraction of the wall due to variations in wall temperature conditions after completion of the installation. With grooves 17 positioned along the edges of the panels, and

Patented June 9, 1959 fl'l'llkfllbngfihe vertical" and; horizontal metal lath joints 14; it has-been found that cracking in the central areas of the panels is obviated and; the fissures or gaps which result item contrae ionand snansion ftthe walliate i= reetedf albnggthev lines ofjthe; ggooyesi momentoinsure. comp ete; air sealing; i he amen;

additionaljiihishlhyer:29f may he annliedt n he te m. i; an asphaltic' sealing compound which is appliedoverthe entire surface. of h pl s ic insul tion: layer. 16, as to; filL all; groov s: 17' and 9' and o. pr d an. o te finish oat f; about; thick. ey nd h fi st fini h o t 16.1 The sealing comnonndir ma ns n a omewhat exib a conditionandj thus tendstqmaintain aelos e over ra ks; which may djevelog in thesnbjacent layer 16.

Whereas the resent inventionthas een llus r d n dsCI Bedfherein, with pa tienlar reference to afluigl heater furnace. wall, it is; to be understoodi that the invention isgsimilarl'y applica le t wal for oth r rms pna insnlating; material,v p nded. m tal ath. atransd; a

the. outer side. of. said, material n adj in ng eq a g t ar sheets presenting nner and outer. vetlanpins, marginal portions forming join s. hetebetwee t i h exten in. intersecting, directions; in herplane. of. s id heets a. ayer. of; Elastic. heat insulating material. of the nat r emen within whichtsaid latttis. embedd d to. a depth. resumes,

in; a. ROItiOD. at said lay r. xt nding ut a ly beyond said lath, said outer layer portion having grooves formed therein from its outer surface to said joint in substantial alignment with the outwardly disposed edge of said marginal portions of said lath at said joints, said grooves being formed along lines extending in said intersecting directions and along a ilne parallel to and intermediate said joints, and an exterior flexibly yielding sealing compound filling aic ts q v ss a d ormin exterior pervious coating for said plastic material.

2, In, a hot; gas chamber -wall comprising. heat; insglat-w ing-materi-al; expanded met-a1 lath arranged at theouter side of said material in adjoiningsheets presentinginner and ter; oi e apn nama inal por i ns ima n ri therebetween, means anchored adjacent the inner 'side of said wall for retaining-each of said'sheets of metal lath in predetermined position relative to the hot gas side of said chamber wall, said retaining means spaced from the ammal. por ons at ea h. heet o metal ath and l nd na nne ns onisrn a e niemhets ttaage i a laamr s n 'asementw ta ppo ite side, o said lz s s. a level thardleaabl plas s. he nsu a mat t atw t iinw lt aid ath s nt iedcled aitlj ast s ns latin -mater el; ns a roove. fo med her in r m. ts ite amn s a bs ml a al nment th. he. u w d y seas d e e. f: sltma s a'al or n i aid, h. at a d" iq t tt. nd; n aterio tflexibly y slslah e a n qqmno ad fi i sa d sma e. andit tmins a mnet s s a na m a si las i mater al: