US1666028A - Fluid heating - Google Patents

Description

April 10,1928.

1,666,028 J; E. BELL f FLUID HEATING Filed July L924 14 Sheets-Sheet l INVENTOR l WA'ITORNE J-. BELL- FLUID HEATING. Filed July 1'1, 1924 v 4Sheis-Shi 2' INVENTOR 8/ v ATTORNEY,

J. E. BELL FLUID HEATING- I Filed July ,1924

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ATTORNEY \E 3 n o UD QQQDUDDUUQQGUDU April 10, 1928;

J. v E. BELL FLUID HEATING 4 Sheets-Sheet 4 r INVENTOR Filed July 1924 Patented Apr. 10, 1928.

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JOHN E. BELL, OF BROOKLYN, NEW YORK, ASSIGNOR -TO FOSTER WHEELER CORPORA- TIONyOF NEW YORK, N. Y., A CORPORATION OF NEW YORK.

FLUID HEATING.

Application filed July 17,1924. Serial No. 726,584.

one side to a source of radiant heat at high temperature, and is concerned with the mechanical construction and arrangement of such apparatus, and in particular with the provisions made for accommodating or re-- straining the tendency of the apparatus to change its form and dimensions as a result of its thermal expansion and contraction.

The invention was primarily designed and especially adapted for use in connection with steam superheaters composed of elements each formed of one or more sections with each section several feet in length and having its walls substantially thicker than ordinary steam pipes having the same cross sectional area for steam flow. These sections may well be formed of caststeel, and in such case are ordinaril rectangular in cross section with the out ine of'the element and of the steam channel therein, each elongated in transverse section in a direction parallel to the'heat absorbing surface of the element.

When such anelement is put into use, the inner side of the section ad acent the source of radiant heat is heated to a temperature appreciably above that of the opposite or outer side of the element, and the sides of the element transverse to the heat absorbing surface arehotter at their edges adjacent the heat absorbing face than at; theirthe element to stress if the latterwere free to bend and straighten out inthe manner described. a p In practice, however, this uniform graduation in thetemperature of themetal of theelement does not exist. The side of the element remote from the heat absorbing face will be cooler adjacent the steam channel than at its face remote from the steam channel owing to the cooling action'of the steam and the fact that the heat which that side supplies to the steam is received wholly or mainly by conduction through the portions of the element which are transverse to the heat absorbing? face. In consequence, when the element is put into the service and thereby heated up, the element tends to bend into the form of an arc with its convex side toward 'the source of radiant heat, but thisv bending setsup internal stresses which tend to compress the material in the portion of the element adjacent the source of radiant heat and to stretch portions of the element more remote from the source ofjradiant heat. In the practical use of radiant heat superheaters, the temperature to which the hotter portion of the element is subjected is a good annealing temperature, while the temperatureof the portion of the element more re mote from the source of radiant heat-is be v low the annealing temperature.- In Iconseis subjected to a compression stress it yields more or less to this stress and takes a .per-' manent set. When thereafter the element cools down, it does not tend to return to its original straight form, but to bend into the form of an are having its concave side toward the source of radiantheat. To some extent this change in form is cumulative with successive heating up and cooling off ofthe element, and the latter will eventually acquire a permanent curvature when cold with its concave side toward the furnace.

Where the elements are comparatively short, say 4, 5, or 6 feet in' length this ultimate curvature is not ordinarily sufficient to be particularly objectionable, and I have found that such elements may well be so quence, when the hotter side of the element mounted that they are free to make the changes in form which the changes in temperature tend to produce. With elements of greater length-lmwever, the distortion in the assembled structures which the temperature changes in the elements-tend'to produce is objectionable and 'should' be restricted or prevented. To this end, I mount the elements in a supporting structure adapted to permit the bodily elongation and contraction of the elements, but effective to limit the otherwise substantial bending movements of the elements as they are heated and cooled.

Advantageously in many cases, the supporting framework or structure and the elements.

are assembled to form aself-contained unit which can be mounted in a furnace wall and which will absorb the stresses due to changes in temperature without transmitting any portion'thereof to the other portions of the furnace walL. The tendency of a metal such as cast steel to elongate and contract in response to changes in its temperature is notuncommonly regardedas a'practically irresistible force. 1 have found however, that ,with cast steel elements such as are now being employed in radiant heat superheaters, the tendency of the element to bow into arc 't'orm asthe result of the temperature changes to which it is subjected, amounts. only to something like 400 pounds per foot of length a better understanding of the invention,

however, its advantages and specific objects obtained with its use,'reference should be had to the accompanying drawings and descriptive-matter, in which 1 have illustrated and described some of the various forms of construction which may be employed in accordance with the present invention.

Utrthe drawings:

Fig. 1 isv an elevation partly in section, of

a portion of the wall of the combustion chamber of a boiler furnace incorporating a rad ant heat superheater;

\ Fig. 2 IS a vertical section taken on the 'line 2-2 of Fig. .1;

Fig. 3- is a plan view partly in section on the line 33 of Fig. 1;

Fig. 4; is an elevation taken similarly to Fig. 1, illustrating a modified construction;

Fig. 5 is a section on the line 5-5 of Fig. 4;.

Fig. 6 is a section on the line 6-'6 of Fig. t;

Fig. 7 isan elevation of a portion of the outer side o1 still another form of.combus tion chamber furnace wall superheater;

Fig. 8 is a section on the line 88 of Fig. 7; j i Fig. 9 is a section on the line 9-9 of Fig. i

Fig. 10 is a partial elevation of a furnace wall supcrheater, comprising short elements allowed freedom to bend;

Fig. 11 is a sectionon the line 11--11 of Fig. 10 and Fig. 12 is an elevation of a portion of the outer side of the furnace wall shown in Figs. 10 and 11. 1

lln the drawings, and referring first to the construction shown in Figs. 1, 2., and 3,.A. represents the housing wall of a boiler furnace, at the rear ofthe combustion chamber a, which is beneath the boiler water tubes 1B. Incorporated in the wall A and forming apart thereof, is a radiant heat superheater composed of cast steel elements G, rectangular in cross section, as shown in Fig. 3.

Each element C is connected at. its ends through transverse and more or less flexible pipe connections D to the steam inlet and outlet headers E and E, and each element Cis anchored at its center by a suitable con nection to a horizontal It beam F. In the particular construction shown, wherein the superheater extends the full width of a boiler furnace of large size, the superheater is in ettect divided into two sections, with an'it beam F for each section-the two I beams F being arrangedend to end and each con-- nected at its end adjacent the other to a common vertical lt beam Gl fFj'At its end re mote from the I beam G, each ll beam F. is

- connectedto a veptical channel bar H. Each channel bar H is'bonnecttid at its upper and lower ends totlie upper land lower ends of the It beam G channelbars ll. Themembers F, G, H; and it form the main mem.- bers of a supporting framework for the superheater which is strong enough and rigid enough to hold the superheater elements C against fiexure when connected to the latter, as hereinafter described, and which is adapted to be incorporated in the furnace housin wall and carry the weight of the portion thereof above the superheater.

To connect each element C to the K beam F at its rear a yoke-like part 0 is welded or otherwise rigidly secured to the rear side of the element. lhe yoke-like part C strad dles, and "is connected by a through pin J to the tongue J "formed by the adjacent flanges of oppositely facing angle bars riveted to theft beam F. To compensate for the various elements 'G and yokes C and facilitate assembly, the space in the parts C is of a width greater than the thickness of the tongue J so that by means of washers J on each pin J (shown better in Fig. (i), the corresponding element C may be vertically adjusted.

At each end each, element C is connected to the'corresponding channel beam I by provisions which do not interfere with the lonnonuniformity in relative proportions of gitudinal expansion and contraction of the element but do prevent movement of the element toward and away from the I beam 1. 'these provisions as shown comprise a tongue-like projection C welded or otherwise secured to the end of the elementG and'a vertical pin K by which the tongue C is connected to the side walls of a channel bar K, the base ofwhich is secured against the adjacent flange of the it beam 1.

Advantageously and as shown, the channel bars K are formed of cast steel and are each 4 of a length equal to the width of some three or four of the elementsYC. The space be-- space between the elements C and the inneredges of the frame members F, G, H, and I be apparent that the elements C may elontween the parallel flanges of the channel bars K is sufficiently. greater than the. thickness of the tongue projection C to permit the latter to slide along the pin K as required to accommodate the bodily longitudinal expansion and contraction of the elements C.

In the preferred construction shown, the

is packed with a suitable heat insulating and gas leakage preventing material as Sil-o-Cel, and this material is held in place by cover plates L secured to the members H, J and K.

The bottom horizontal frame members I may rest directly upon the subjacent masonry portion ofthe wall A, but, onaccount of the necessity for providing for the longi-' tudinal contraction and expansion of the elements C and the consequent up and down movement of the end connections, D, I mount the members I, in the construction shown in Figs. 1, 2, and-3, on cast metal pedestals M incorporatedin the housing and each engages some wall, and provide" a space between the subjacent brickwork portion of the housim wall into which the upper ends of the pedestals M extend and through which the lower end connections D pass. This space is advantageously ,filled with Sil-o-Cel or analogous heat insulating and gas leakage preventing material, which will yield to permit of the movements of the pipe connections D as the elements G expandand contract. As shown,

the outer end of this space is closed by a cover plate 0 formed in sections and apertured to receive one or two pipes D. The

sections of the cover plate 0 are held against the outer edge of the Sil-o-Cel filled space by angle bars 0 between which the pipe connections D are clamped. As shown, the angle bars 0 are formed in short sections two or three of the pipes D.

At the upper end of the superheater, a

space is provided between the upper channel beam I and the brickwork of the boiler housing wall above the superheater through which the upper pipe connections 'D pass, and in which they are surrounded by Sil-o- Cel or the like as at the-bottom of the superheater. For this purpose, cast steel elements in the form of I bars P are mounted on the top of the upper beams I and support sectional cast steel cover plates P on which the brickwork above the superheater is supported. The outer edge of this space is closed by parts 0 and 0, similar to those employed at the bottom of the superheater.

The flexibility of the pipe connections D may be sufficient to accommodate the longitudinal expansion,- and contraction of the element C when the headers E and E are rigidly mounted. Advantageously. in some cases. however, the headers E and E may be yieldingly supported to reduce the bending gate and shorten as their temperatures increase and decrease without putting objectionable stress on'any portion of the apparatns, but their tendency to bow in planes parallel to their length-and transverse to their heat absorbing surfaces will be prevented by the superheater supporting framework if the latter is strong enough as it may well be to withstand the tendency of the elements to'bow. The maintenance of a smooth and comparatively flat heat absorbing superheater face is especially desirable to insure the effective operation of thesoot blowing provisions C provided for sweep ing the face of the ,superheater with jets of steam or other cleaning fluid in order to remove the deposited furnace dust. The super-heater as a whole forms a self-contained unit which is incorporated in the boiler furnace housing and the stresses set up in diflerent portions of the superheater structure, and such relative movement of the parts thereof as are permitted, in' response to the changes in temperature to which the superheateris subjected, do not react upon or disturb the masonry portions of the boiler housing. i

In Figs. 4, 5, and 6 I have illustrated a construction which is essentially the same in its general features as that shown in Figs. 1, 2, and 3, except as to certain specific differences resulting from the fact that the ends by two horizontal channel beams HA.

The connections between the elements C and the beams FA and IA are similar'to those between the elements C and the beams F' and I in the construction first described. In Figs. 4, 5, and 6, the tendency of the elements to rotate under the action of gravity about the pins K and J is resisted by the end connections D which for this 'purpose are supported adjacent the elements C by sectional supporting members R formed with horizontally elongated slots R to per-- mit the bodily elongation and contraction of the elements C. As shown, the plates R are carried by vertical channel beams'IB alongside the channel beams IA and separated from the latter by a space, which may be together.

filled with Sil-o-Cel to provide a gas tight and-heat insulating packing about the end connections D, the outer edges of these spaces being closed by cover plates'O' and 5, and 6, the elements C are arranged in two horizontalbanks, the two banks being separated by refractory materials which may be supported on the upper element in the lower bank. The possibility of thus holding re-' fractory material incorporated in the heat absorbing face of the superheater is an ad vantageous one, as it is sometimes desirable to thus reduce the amount of'heat absorbing surface ofQt-he superheater without corre spondingly reducing the extent of area. of the boiler furnace wall formed b heater as awhole.

The principal formal differences between the construction shown in Figs. 7, 8, and 9 and the constructions in Figs. 1 to 6 arises from the fact that in Figs. 7, 8. and 9, the main elements of the supporting framework for the superheater are formed by a multibar FE having its horizontal flange riveted to the horizontal flange of an angle bar FF which in turn is riveted'to thebeams GB.

-o enin F in the vertical fian e of an an le P b c:

Each element C is similarly connected at its,

lower end by angle. bars FE andFF to the beams GB. The openings F in'the angle bars'FE for the-boltscarried by the lugs y the superplicity of l beams GlB which are parallel to the superheater, the elements C of which are vertical. The E beams-GB are connected at their ends by channel beams 1B.

' The intermediate beams GB as shown are arranged in adjacent pairs with the two beams of each pair spaced away from one another a small distance and the adjacent beams of adjacent pairs spaced away from one another by a greater distance. The adacent beams of ad acent pa1rs are connected C? are larger than the bolts to accommodate the elongation of the expansion and contraction of the elements G, and are also enlarged horizontally to compensate for irregularities in the shape and proportions of parts and thereby facilitate assemblage. The bolt or rivet holes F in the angle bars FC may be similarlyelongated for the same purpose as shown. Asshown in Fig. 8 the wall in which the superheater is incorporated forms the rear wall of a combustion chamber which extends under the front por tions only of the water tubes and which supports the lower edge of a baffle extending across the water tubes. Thisba'tfle is supported (in hollow box-like parts PA of cast metal through which the upper end connections D pass loosely." The space within the boxes PA around the end connections D, are

packed with Sil-o-Cel or the like, the outer.

ends of these spaces being practically closed bv short horizontal beams FE and brackets FE about midway between the top and bottom ends of the elements C. The two beams of each pair are alsdconnected by horizontal webs F18 and brackets F13 In this construction, the elements C are formed in two sections of approximately the same length which are connected end to end by an internal threaded nipple (3 and also by welding the adjacent ends of the sections Each element C is anchored adjacent its center by two connections one to each end of each of the two sections of the. elements; The connections for the upper sectionscompriserivets or bolts for securing lugs C welded to the sections to the'-vertical flange of an angle bar FG- having its horizontal flange riveted to the horizontal flange of a second an le bar FD, the latter havingjts vertical ange riveted to the beams GB. Similarly the lugs C at the top of each lower section element.are attached to the vertical flange of an angle bar FC having its horizontal flange riveted to by the super-heater header E which in this construction is connected to the elements 0' by rather short pipe connections I). The lowerend connections D pass through cover .plates 0 which overlap the casing plates .L

andLA between the elements C and their supporting framework.

lln Figs. 10, 11, and 12 I illustrate a construction in which the sup'crheater elements C are comparatively short and are permitted -to bow as well as to elongate and contract in response to the temperature changes to which they are subjected. In the particular form illustrated in Figs. 10, 11, and 12 the Jsuperheater is incorporated in the bridge wall AAforming the rear wall of'the combustion chamber proper of a boiler furnace in which the combustion chamber underlies the front portions only of the boiler tubes B with a baflle 13* extending across .the bank of tubes and resting on the upper edge of the bridge wall. however, that the described construction is not limited to usein the type of boiler re- It will be 'understood,

ferred to, but may be usedin the outer wall of the combustion chamber underlying the entire bank of water tubes.

In Figs. 10, 11, and 12 the lower ends of the elements C rest on the portion-of the bridge wall beneath them, and the lower transverse pipe connections D are restrained against substantial fiexure by supporting means which comprises a sleeve U for each lower end connection D through which the latter passes. Each sleeve U is expanded at its ends into openings formed for the urpose'in the inner and outer sides of cast iron parts T in the form of boxes open at their tops and each of such length, measured parallel to the length of the bridge wall as to accommodate: a plurality (live as shown) end connections D. The box-like castings.

T may be strengthened by internal ribs orwebs T. The parts T rest on cast metal supports W in the form of, channel bars, and the supports W and parts T are bedded in suitable cement on the subjacent portion 1 of the bridge wall AA proper. The spaces illustrated in Figs.

her

in the parts T surrounding the sleeve D may be surrounded by ganister A or the like, which forms a support for the masonry portion' A of the bridge wall AA back of the elements Ci 1 v The wall portion A supports at its top, provisions analogous in'character to those 1, 2,.and 3, and 7, '8, and 9 for-permitting the upper end connections D to bend in response to the changes in form and 'length'of the superheater elements as their temperatures vary. Theprovisions shown for this purpose comprise similar castings X and XA having flat top and bottom portions and vertical web portions X, providing open ended'channels one for the upper endconnection D, the inner end of each of which is received in a corresponding channel of a member XA while an outer portion is received in a channel in a mem- X. The castings X and XA are shown as resting on cast supports WA having flanges at their under sides and bedded in a suitable cement on the top of the wall portion.A. Cast metal cover plates Y on the tops of the parts X and XA close the joints between the latter and directly support tiles A on which the bafiie B rests. The spacesabout the end connections D within the rear members XA and between those members and the outer members X are packed with Sil-o- Cel or the like. The upper end connections D are connected into a header EA which is divided into inlet and outlet portions E and E respectively, by a central diaphragm E". The lower end connections D are connected into a header EB closed at each end. This arrangeinentof headers is desirable in some cases as in the particular construction illustrated in which the super-heater is composed of elements which are five feet or so long and eiitends the full Width of a combustion chamher which may be twenty feet wide or so, as it'permits the steam admitted to the comp'artment E of the header EA to pass first through the elements!) connecting the compartment E to the header EB and thence through the remaining elements C- connecting the elements to the oompartmentEA. As shown the header EA and EB are each anchored at one side of the boiler as by means of saddle blocks E and clamping yokes E and at the opposite side of the boiler the end of each header rests upon acorresponding roller support E. g

4 With the construction shown in Figs. 10, 11, and 12, the upper end of each element C is free to rise and fall and to incline to the vertical in response to the tendency of the sectional supports for the lower end connections D'provide sufficient flexibility to avoid objectionable strains from such stresses as are created by the thermal elongation and contraction of the'lower header EB. These desirable results are obtained moreover with construction and with a minimum tendency to leakage through that well. While as previously eXplained,the-repeated heating and cooling to which the elements 0 of Figs. 10,

11, and 12 are exposed will eventually result in the bending of the elements G into bow form withtheir concave sides toward the combustion chamber X portions as shown,

and whilethis deformation tendency is cumulative -,for a period after the super- 'a relatively simple combustion chamber wall heater: is first put into use, a. stable shape is ultimately attained and in this stable condition the curvature of the short elements is not excessive, and in particular is not sutficient to interfere with the efie'ctive operation of the soot blowingprovisions'C.

Aside from prevention of objectionable deformation of the elements themselves by restraining'their bowing tendency, there is a special advantage inpreventing bending movements'of .the end portions of the elements because of the beneficial effect on the transverse end connections. When the head ers are rigidly supported, the bodily'elongation and contraction of the elements 0 necessarily results in corresponding bending movements of the endconnecting nipples or tubes D. The tendency of such bending movements to work the nipples D loose from the elements and the headers .is materially augmented, of course, by the bending movements of'the elements when the last mentioned movements are not restrained. In

wvith respect to the connections between the same bowing tendency at the same time. In

elements C and the nipples D, than between the latter and the headers, as it'is more readv plane parallel to its length and transverse ily feasible to make a good connection between the headers and nipples D than be tween the latter and the elements.

The connection of the elements G closely adjacent their, ends to a rigid supporting framework, as in the construction shown in Figs'.,l to 9, greatly reduces the diiiiculty of maintaining the strength and tightness of the joints between the nipples vlD and the elements. Somewhat the same advantage is secured with the construction shown in lfiigs. 10, 11, and'12 by connecting each element C at each end, and particularly at its upper end, to the corresponding ends of the other elements as by. means of an angle: bar F connected to the elements closely adjacent the nipples D, by bolting them to lugs C formed on the backs of the elements. The

advantage of thus connecting the elements C j together adjacent their ends is, largely 'due to the fact that in practical operation the various elements are not all subjected to the consequence, the distortion of an element in which the bowing tendency is relatively large, is restricted by its connection to the elements in which the bowing tendency is relatively small. lln practice, the use of the bars F and particularly of the upper bar F 9, makes it practically possible in some cases to use rigidly mounted headers, where otherwise headers mounted on yielding supports would be required.

Certain features of construction and arrangement pertaining to a-furnace wall superheater having furnace wall lining elements with flexible-transverse end connections extending through the furnace wall, and pertaining to the combination offurs nace wall lining superlieater elements with a rigid metallic supporting framework not claimed herein, but disclosed in common herein and in my prior application Serial No. 607,781, filed December 19, 1922, are

claimed in said prior application.

While in accordance with the provisions of the statutes, ll have illustrated and dc scribed the best form of my embodiment of my invention now known to me, it will be apparent to those skilled in the art that changes may be made in-, the form of. the apparatus disclosed without departing from the spirit of my invention as set forth in the I corresponding use ceaoae ment' absorbing radiant heat at one side' which consists in substantially restraining the tendency of the element to bend in a 'sists in permitting the element freedom to expand and contract in the direction of its length while applying force to the element at points distributed along its length as required to restrain the tendency of the ele- -ment to bend in a plane parallel to its length and transverse to its heat absorbing side.

- 3. In radiant heat absorbing fluid heating apparatus the combination with an elongated channeled element absorbing radiant heat at one side, of supporting means, for said element engaging the latter atpoints distributed along its length and thereby holding the element against bending movements in a plane parallel to its length and transverse to its heat absorbing side while permittinga bodily elongation and contraction of the element in the direction of its length. 4 I

i. Radiant heat absorbing fluid heating apparatus comprising a plurality of elongated channeled elements arranged side by' element while substantially restricting the tendency of the element to bend in a plane transverse to said frame.

5. In radiant heat absorbing fluid heating apparatus the combination with a plurality 'of elongated channeled elements. arranged ill) side by side, of a rigid supporting frame to which said elements are connected adjacent their ends'and at one or more intermediate points by means permitting the thermalelongation and contraction of the elements but preventing movement of the elements at their points of attachment to the frame toward and.away from the latter.

6. Th radiant heat absorbing fluid heating apparatus the combination with a plurality of elongated channeled elements arranged side by side, of a rigid supporting frame to which said elements are connected adjacent their ends and at one or more intermediate points by means permitting the thermal elongation and contraction of the elements but-preventing movement of the elements at their points of attachment to the frame toward and away from, the'latten-said frame in planes parallel to their length and transf v verse tothe frame as a whole.

7. In radiant heatabsorbing fluid heating apparatus the combination with a plurality ofelongated channeled elements arranged side by side, of a rigid supporting frame to which said elementsfare connected adjacent their ends and at one or more intermediate points by means permitting the thermal elongation andcontraction of the elements but preventing movement of the elements at their points of attachment tothe frame to- I ward and away from the latter, said fiaine comprising structural'members parallel to said elen ents'and of a collective longitudinal stifi'ness'suificient to resist without ap- I preciable fiexurethe stresses which are created in the elements as their temperatures vary and which tend to bend the elements in planes parallel to their length and transverse to the frame as a whole and structural members transverse to the first mentioned members through which the latter are connected to said elements.

8. The combination with radiantiheat absorbing fluid heating apparatus comprising elongated heat absorbing elements and transverse end connections to said elements, of a furnace wall having metallic parts incorporated therein to form channels through which said end connections extend and in. which they are loosely received, and heat insulating material packed in said channels about the end connections to restrict air leakage through the channels while permit:

ting movements of the end connections re sulting from the thermal expansion and-con traction ofthe elements.

9. The combination with a radiant heat absorbing fluid heating apparatus comprising elongated heat. absorbing elements and a 7 mg apparatus comprlsinga row of elongate ed channelled elements each absorbing .ra-

transverse end connection to one end of each eleinent, of a furnace wall formed -with channels through which said end cdnnec; tions are loosely passed and at the inner side of which said elements are d sposed,- a

header at the opposite'side of the wall to' which one end of each transverse connection is connected, means incorporated in the; wall to which each of said elements is anchored at a distance from itssaid end connection, and a support for said header adapted to yield to accommodate the thermalelongation,

and contraction of said elements.

10. The combination with a radiant heat 16th day of July A. D.

absorbing fluid heating apparatus comprismgelongated heat absorbing elements and transverse end connections to said elements,

of a furnace wall having metallic parts incorporated therein to form channels through which said end connect-ions extend and in which they are loosely received, and heat insulating material packed in said channels about the end connections to restrict air leakage through the channels while permitting movements of the end connections resulting from the thermal expansion and contraction of the elcments and covers secured to said end connections andclosing the outer ends of said channels. 11. In radiant heat absorbing fluid heating apparatus the combination with a plurality-o'f elongated channeled heat absorbing elements and transverse end connections to said elements, of a combustion chamber wall at one side of which said elements are disposed, a rigid metallic frame incorpor'ated in said wall and metallic portions at the nels through which said end connections extend-through the wall and means anchori'ng said elements to said frame.

12.:A radiant heat absorbing lluid heating apparatus thepombination with elongated, channeled elements provided with transverse end connections, of a furnace wall at one side of which said elements are arranged and which is formed with channels through which said connections extend and in which they are loosely received, an an chorage to which said elements are eonnected at a distance from said end' connections,

a packing of heat insulatingmaterial in said channels abg 'it said end connections adapted to yield totaccommodate movements saidmaterialthrough the outer ends ot' said channels.

i 13. In radiant heatabsorbing fluid heatdiant heat-at one side, transverse connections to the ends of the elements for passing the fluid to be heated through the channels element is connected adjacent one endwhereby the tendency to unequal movements of" the difierent elements.- in response to temperature changes is restricted.

Signed at New Yorkcity, in the county of New York and State of New York, this 1924:. J E. BELL.

in the elements, of a support "to which each

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