US2131080A - Steam generating and superheating apparatus - Google Patents

Description

Sept. 27,1938. Q s TURNER- 2,131,080

STEAM GENERATING AND SUPERHEATING APPARATUS Filed Dec. 17, 1954 v 7-SheetS-She61; l

- INVENTOR. karles .5, f/Yzrrzer ATTOR Sept. 27, 1938. c, s. TURNER STEAM GENERATING AND SUPJEIE H-IEATING APPARATUS Filed Dec. 1'7, 1954 7 Sheets-Sheet 2 C /z arles 8 713M242- Sept. 27, 1938. c. s. TURNER 2,131,030

STEAM GENERATING AND SUPERHEA' I'ING APPARATUS F iled Dec. 17, 1954 7 Sheets-Sheet 3 INVENTOR.

ATTORNE Sept. 27, 1938. RN R "2,131,080

STEAM GENERATING AND SUPERHEATING APPARATUS Filed Dec. 17, 1954 7 Sheets-Sheet 4 I ,5 IN VENTOR.

yftj a i l fmgms.

Sept. 27, 1938. c. s. TURNER STEAM GENERATING AND SUPERHEATING APPARATUS Filed Dec. 17, 1934 7 Sheets-Sheet 5 INVENTOR. @fiarles 5. fizr/ze r- B 0m E yz ATTORNEY 56 5527, 1938. 3 T RNER- 2,131,080

STEAM GENERATING AND SUPERHEATING APPARATUS INVENTOR. bar-[es 5, Er/z er A TTORNE .5.

Sept. 27, 1938.

STEAM GENERATING AND SUPERHEATING APPARATUS Filed Dec. 1'7, 1954 TURNER 2,131,080

'7 Sheets-Sheet 7 IVL ENTOR. @fizzrles 51 larger ATTORNEY Patented Sept. 27, 1938 UNITED STATES PATENT OFFICE STEAM GENERATING AND SUPERHEATING APPARATUS 15 Claims.

This invention relates to heat absorbing and vapor generating apparatus, and although particular consideration is given to water tube steam boilers, it will be seen to be readily adaptable to other heat exchanging apparatus. An important object of the 'invention is the provision of improved means for conducting steam, or other fluid to be heated, transversely through a bank or screen of tubes spaced on close centers, such as constitute the so-called water walls which frequently form part of the generating system of a boiler,

In the past, in boilers of the variety incorporating water walls, it has been considered impossible from a practical standpoint to introduce cross tubes through that portion of the furnace bounded by the water walls, for the reason that the water wall tubes have been commonly spaced too close together to permit the projection. of cross tubes of suitable size therebetween. It is often desirable, however, that a slag screen be positioned in a portion of the furnace directly above the fire and appurtenant that part of the combustion chamber ordinarily bounded by such water walls. It has further been recognized that such position would be an ideal one for a radiant superheater, provided practical means were available for protecting such superheater against burning out. Slag screens in the form of simple water tubes have in the past been so positioned by running the water wall tubes to lesser heights than those to which they would otherwise extend, and projecting the slag screen tubes across thereabove, but as a practical matter it has been found impossible to either extend the slag screen tubes across and through the water wall itself, or to similarly interfit and adequately protect the tubes of a superheater positioned in like fashion in the combustion chamber and extended through water walls.

An important object of this invention, therefore, is to provide means whereby protected radiant superheater tube assemblies and/or slag screen tubes may be projected directly across and through the water wall portions of a furnace, in such manner that steam and water fed to and taken off from said tubes pass directly through and substantially perpendicular to the water walls, without interfering with the action of or flow in the water walls and in a manner allowing full and unrestricted flow through the superheater and/or slag screen elements; as well as to allow the provision of a superheater of the indicated character of virtually any desired capacity, or a slag screen of any desired size.

A further important object is the provision of an improved hollow Wall block for supporting the tubes of a water wall, which wall block is formed to also support and serve as a connecting manifold for transverse superheater or slag tubes extending through and across the space between oppositely disposed Water walls bounding a combustion chamber.

A further object is the provision of' improved means whereby transverse superheater assemblies of the character indicated may be supported by and projected across and through vertical water wall assemblies yet allowed to expand and contract independently of the water walls through .which they extend.

Still another object is the provision of improved manifold and header means for such a radiant superheater assembly, so arranged as to provide double pass of steam to be superheated across the space between and through the water walls.

A still further object is the improvement of the water protected and regulated superheater constructions disclosed in my co-pending patent applications, Serial Nos. 512,675, and 590,108, filed January 31, 1931 and February 1, 1932, respectively,- and the provision of novel means whereby superheaters incorporating the inventions therein disclosed may be projected through and across the space bounded by vertical water walls in the portion of a furnace directly above the fire.

It is also an object to provide in such constructions a novel combined wall block and header arranged to conduct steam or other fluid (either or both) longitudinally and laterally through the spaces between water wall tubes and to and from conductors located inside the area bounded by the water walls.

I further aim to provide an improved water cooled and regulated superheater tube assembly in which a novel arrangement of tubes provides for protection of the steam tubes by the water tubes at one stage of operation, and prov tection of the water tubes by the steam tubes at another stage.

Other objects and advantages will be apparent from the following description wherein reference is made to the accompanying drawings illustratlng preferred embodiments of my invention and wherein similar reference numerals designate similar parts throughout the several views,

In the drawings:

Figure 1 is a somewhat diagrammatic vertical sectional elevation of a straight through cross drum boiler incorporating vertical water walls bounding the combustion chamber, in which the principles of my invention are applied in the installation of slag tubes projected directly through the water walls and across the combustion chamber.

Figure 2 is a fragmentary vertical section showing a portion of the water wall in elevation, taken substantially on the line 22 of Figure 1 and looking in the direction of the arrows.

Figures 3 and 4 are horizontal and vertical sections respectively, taken substantially on the lines 33 and 4-4 respectively of Figure 2 and looking in the direction of the arrows.

Figure 5 is a fragmentary View similar to Figure 2 of another form of my invention applied to a superheater construction.

Figure 6 is a vertical section taken substantially on the line 66 of Figure 5 and looking in the direction of the arrows.

Figure 7 is an enlarged cross section of one of the superheater elements, taken substantially on the'line 'l-'| of Figure 6.

Figure 8 is an enlarged side elevation, partly broken away, of the upper end of a somewhat modified superheater installation.

Figure 8a. is a detailed section taken substantially on the line 8la8a. of Figure 8.

Figure 9 is a view similar to Figure 8 showing a suitable lower end construction for such a superheater.

Figure 10 is an end view taken substantially as indicated by the arrow I of Figure 9;

Figure 11 is a cross section of one of the superheater units, taken substantially on the line llll of Figure 9, and looking in the direction of the arrows.

Figure 12 is a cross section taken substantially on the line l2-l2 of Figure 9, and looking in the direction of the arrows;

Figure 13 is a fragmentary assembly view showing in side elevation and somewhat diagrammatically a superheater construction of this character and the appurtenant furnace portions and connections.

Figure 14 is a cross section taken substantially on the line I4I4- of Figure 13, and looking in the direction of the arrows.

Figure 15 is a view similar to Figure 9 of another and modified lower end construction usable in such a superheater.

Figure 16 is a vertical section taken substantially on the line l6-|6 of Figure 15 and looking in the direction of the arrows, showing also a somewhat modified tube assembly structure which may be used; and

Figure 1'7 is a cross section taken substantially on the line I1l1 of Figure 15 and looking in the direction of the arrows.

Referring now to the drawings, Figure 1 will be seen to show a cross drum boiler of well known form, serving to illustrate a typical field of application of my invention. The furnace is shown provided with a grate 21 adapted to support a fire bed, the combustion chamber 25 being bounded by water walls formed by tubes 28-29, while boiler tubes 30 extend across. the top of the combustion chamber in conventional fashion, between inlet and outlet headers 3l-32. A steam drum 34 serves to collect the steam generated in the boiler, while the flue 35 is located directly above a portion of the combustion chamher.

Since the present invention is primarily concerned with those portions of the furnace containing the vertical water walls and bounding the supplied at their lower ends through water inlet header 3!}. As indicated in Figures 2 and 3, the spaces between the water wall tubes are narrower than their outside diameters, so that it would be impossible to project simple cross tubes of like size through the spaces between them. The

water wall tubes are shown supported and shielded principally by wall blocks 42 of conventional construction, which may be cemented to the tubes in the customary fashion and bolted in place as by means of studs 44 and straps 45 or in any other usual or suitable manner.

Spaced at desired intervals and similarly supported among the conventional wall blocks 42 are special hollow blocks 50 arranged in opposed pairs in such manner as to support between the elements of each pair one or more slag screen water tubes as 52 projected across the combustion chamber therebetween and secured to and opening into the interior of the blocks, as by being terminally fitted into suitable (undesignated) openings in the exposed faces of the blocks, to which they are welded as at 53. Such slag screen cross tubes are ordinarily spaced farther apart than are the tubes of the water wall, and the special hollow blocks are of course only used at the locations in which it is desired to place cross tubes, but however spaced and disposed, the special blocks preferably conform in external contour to the regular blocks 42, at least in their back portions which engage the water4= wall tubes, and are held in place similarly to assist in the support and protection of the water wall tubes, as by studs 58 and straps 59. The fronts of the blocks, facing the combustion chamber, are of course considerably wider than their rear faces, which are limited by the spacing of the water wall tubes, and in order to provide full flow through the spaces between such tubes, and unrestricted supply to and offtake from the cross tubes, I preferably elongate the special blocks vertically, thus lengthening vertically that portion of the hollowed chamber therein extending between the adjacent water wall tubes, and providing a relatively narrow passage 54a of extended height connected to and forming part of the interior chamber 54, as best shown in Figures 3 and 4. To the rear faces of blocks a plurality of tubes as 55-65 may be connected, projecting rearwardly into supply and ofitake headers, as 56 and 51. which these are arranged and held in place (as by welding, at 5869) is best shown in Figure 4 showing the inlet end on a larger scale. The outlet end and connections may of course be similarly arranged. The use of a plurality of connect-"60 ing tubes 55-65 enables handling the full capacity despite the restricted size of the tubes, which is of course limited by the width of the portion 54a.

The inlet header 56 is shown as connected to a mud drum 39 of the water wall, while outlet header 5! conducts the steam generated in the slag screen tubes 52 to steam drum 34 through a connecting pipe 6|.

It will be appreciated that by virtue of thisand in a manner permitting the useof cross tubes- The manner in 55 of capacity as great as or greater than the water wall tubes. The sizes of the chambers in the hollow blocks may of course be varied as desired, and the number and proportions of the connecting tubes changed in accordance with the capacity of the cross tubes.

Figures 5, 6 and 7 disclose another application of certain of these principles, enabling installation of a water regulated superheater in a fire chamber surrounded by water walls. The superheater shown is of the general construction and intended to be operated in the manner disclosed in my copending applications Serial Nos. 512,675 and 743,068, filed January 31, 1931 and September 7, 1934, respectively. The vertical water wall tubes are designated 28a, and the conventional solid wall blocks by which they are principally supported and shielded 4211; At suitable intervals, and preferably intersp-aced with the solid wall blocks, are a plurality of hollow wall blocks 50a so positioned in pairs on opposite sides of the combustion chamber as to be adapted to support between them one or more water regulated superheater tube assemblies, as T5, projected across the combustion chamber and disposed at an angle to the horizontal,

Each superheater unit consists of a central tube 76 having a fluted exterior, the peripheral flutes being proportioned to accommodate a plurality of longitudinal tubes T! which are fitted thereinto and welded in place, as at 18. As is best shown in Figure 7, the weld portions 18 bridge the spaces between the outer tubes 17 and integrate them with the peaks of the flutes, providing integral heat bridges between such tubes and the central fluted tube along such welded paths only, while since the interfitted portions between the welds are non-integral, the cleavage between them prevents ready heat transference therebetween. The flutes and the tubes Tl fitted thereinto are preferably helically spiralled about the central tube to equalize the radiant heat impingement on and heat absorption in the several tubes 11. Tubes 11 are ordinarily used for the conduction of steam to be superheated, while the water or other fluid for temperature control is passed through the central tube 16.

The inlet and outlet ends of the superheated assembly may be of similar construction. One end (the lower or water inlet end) only is therefore illustrated in Figure 6. As there shown, the water tube '16 may be projected directly through the wall block 500. and connected toa water supply pipe as '19, while the steam tubes ll may open into an inner chamber as within the block, to which are connected steam tubes 81. It will be seen that the tubes 768I may be arranged in vertical alignment and so accommodated in the narrow space available at the rear of the block, while the frontal area of the blocks and so the proportions of the superheater unit connected thereto may be of virtually any desired size, being limited only by the maximum practicable size of the face of the block. Although the steam may be run in either direction through the steam tubes 11, it will be assumed that in construction shown in the drawings, the steam to be superheated is fed downwardly through steam pipes 8| and then into outlet steam header 82, while the water for temperature regulation is fed into the same end of the assembly through pipe 16-19. At the other (higher) end of the assembly (unshown), like coupling arrangements may be provided for taking off the saturated steam generated in the water tube, and for feeding into tubes 11 the steam to be superheated.

A throttle valve as is disposed in the water inlet, and may be automatically regulated in response to the effluent steam temperature as by means of thermostat 86, acting through valve regulating means diagrammatically illustrated at 81, connected to and controlled by the thermostat. The valve is so constructed and the regulating means so adjusted that during normal steamflow the water in the central tube 16 is I away virtually all the radiant heat impinging upon the surface, and so prevents superheating of steam within the tubes 11 in such area. Above the water lever, however, the central tube contains practically nothing but saturated steam, (and that in reduced quantities due to the low water level) the heat absorbing power of which is insufficient to conduct away more than a very small proportion of the radiant heat impinging upon the exterior. Superheating accordingly takes place in such portions, and it will be apparent that by so throttling the water supply as to change the water level within the central tubes 16, the effective superheating area may be varied and the temperature of output steam thereby controlled. The thermostat and valve regulating mechanism may be so arranged as by varying this level to maintain any desired output steam temperature, or valve 85 may, if desired, be regulated by hand.

Preferably hand operating means as 89 is provided whether or not thermostatic regulation is incorporated, in order that upon starting the commences to flow, such hand regulated portion,

which constitutes a bypass, may be closed, whereupon evaporation within the central tube will quickly reduce the level therein to the proper one to provide the superheating area which will furnish output steam at the proper temperature, which level will be maintained and varied by the thermostatic regulating means to hold the superheated steam at the set temperature. Although differences in constructional features and apparatus and installation will be perceived, the described method of operation will be recognized as that disclosed and claimed in my copending application Serial No. 512,675, filed January 31, 1932, issued May 14, 1935, as Patent No. 2,000,906.

A somewhat modified superheater, shown in Figures 8 to 14 inclusive, comprises one or more superheater units each constituted of alternate water and steam tubes 16b and 11b assembled in the manner best indicated cross sectionally in Figure 11. As there shown the steam tubes 11b are provided along opposite sides with reentrant channels so proportioned that when two of such tubes are arranged side by side with the channels in opposed parallelism, a water tube as 75 16b of suitable size may be fitted therebetween and in-the'space formed by the opposed channels in such manner as to be almost but not quite completely enclosed. .The space remaining, defining the-spacing of adjacent steam tubes by the interfitted water tube, is preferably closed by welds as 1812- which are thus disposed at and complete the surface of the assembly. The welds also provide integral heat bridging means between the outer surfaces and those portions of the enclcsedwater tube nearest thereto, while the cleavage between the other interfitted but unconnected portions (1%) of the water and steam tubes prevent ready heat exchange therebetween.

In the unit shown in Figure 11 four of such channeled steam tubes 11b and five of the interfitted Water tubes 16b are incorporated. The outer faces of the end water tubes 16?) are shielded by a plurality of smaller steam tubes as 90, which are welded thereto and to the adjacent steam tube 11b in a manner clearly shown in the drawings, and for a purpose which will presently appear.

The vertical elongation of the superheater unit by arranging the tubes one above another in this manner facilitates the use of tubes which are small enough to enable the assembly to slidably fit between the water wall tubes through which and the furnace wall the unit is to be installed, while yet providing the desired superheating surface in a most compact form. Such superheating surface is of course Variable by varying the number or tubes in a unit as well as by varying the number of units, while the effective surface may be subjected to constant control by water level regulation as in the embodiment previously described.

Two such units are shown arranged in series in the embodiment illustrated in Figures 8 to 14 inclusive, which serially arranged-units are generally designated I00 and IIlUd. They are preferably disposed at an angle to the horizontal, and may be longitudinally slidable with respect to the furnace and water walls at least at one end, as above stated, to allow for expansion and contraction.

Slidability of the units at their lower ends is provided by allowing the tube assemblies to slide freely between the water wall tubes 28!), and in suitable openings (undesignated) in the wall of the furnace. The slidable support at this end may be-furnished by a pad as I0l, welded to the bottom of the portion which projects through the wall, the pad being in turn slidable in the wall upon a cross beam- I02 having a suitably inclined top web. The lower ends of the steam tubes which project from the furnace wall support and are connected by a floating vertical cross header H35, in openings (undesignated) in which they are welded or otherwise suitably sealed, as at I06. The cross header will presently be described in greater detail.

At their upper ends the steam tube 111) of one unit (the upper in the shown construction) are connected to an inlet steam header H5, while the steam tubes of the lower unit I00a discharge into outlet header II6, from which the superheated steam may be delivered' to its destination through a steam pipe as I21. The steam to be superheated may thus be conducted from header H5 downwardly through unit I00 and crossheader I05 tounit I000 through which it' flows upwardly to discharge header 6-.

The inlet and outlet-headers II-5' I-I6 are-shown formed asvertically elongated hollow wall blocks shaped to fit between and welded to the water wall tubes 28b; as at 53b. The cross-sectional contour and internal construction of the hollow wall .blocks are such that an enlarged head portion projects into the combustion chamber and overhangs the water wall tubes to assist in shielding said tubes and provide the required header capacity, while a thinner tapered or fish-tailed rear portion of each projects through the space between adjacent water wall tubes 28b to conduct steam and cooling water through the space between the tubes of the water walls. The steam tubes terminate in and are welded to openings (undesignated) in the exposed faces of the combined header and wall block elements H5, H6, as'at I5I. To the rear and opposite ends of the thinned back portions of the header blocks supply and olf-take steam pipes I20-I2I are welded or otherwise connected, which pipes are flattened as shown in Figures 8a and 13 to conform in width to the narrowed rear portions of the header blocks.

Upon the aligned vertically extending back portions I64 of header blocks II5-I I6 which project through and from the water wall an outlet water header as I65 is shown carried, being indicated as secured thereto by fishplates I66 and clamping bolts I67. The sides of portion I64 are grooved as at 20I to receive the angular flanges 202 which extend along the edges of the fishplates, and apertured as at 200 to provide communicating channels for the water tubes 161),

which are projected through the hollow interior of the header blocks and into sealed engagement with such channels. The channels in turn terminate in open ends in the rear wall of portion I04, against which end wall a similar cooperating coupling portion I69 is carried by the header I65 and provided with registering apertures 205,

of the tubes I'I6 of both units is thus handled by the single outlet header I65. Such discharge,

which is ordinarily saturated steam, may be conducted to the steam drum of the boiler (unshown) or other desired destination through steam coupling I19.

A water inlet header I I0 is carried at the lower end of the assembly by the floating cross header I05, being mounted on the back of such header in the manner best shown in Figures 9 and 10. Headers I05, I I0 are provided with flanges as II2 through which bolts III are passed to secure them together. The walls formed by such flanges are apertured as at II 3, I I4 to tightly receive the ends of water tubes 16b, which are projected therethrough into sealed engagement with the water header. Water is supplied through supply pipe I9b, (Figure 13) and through the agency of a thermostatically or otherwise suitably controlled throttle valve as I23 the inflow of cooling water may of course be regulated to hold the water at a reduced level within the assembly but inside the zone of heat absorption, as in the embodiment previously described, providing similar water-regulated action. The entire assembly of headers I'05'-I I0 at the lower end floats with the free lower ends of the units which are free to move longitudinally under expansion and contraction, and beam element I02 may be continued and snugly fitted about all sides of the element to frame it closely enough to prevent undesirable air leakage, as shown in Figure 12, the framing portion I02 being bolted as at 581) to ears 5% welded to the water wall tubes 28b.

The smaller steam tubes carried along the exposed edges of the units are so proportioned that the heat paths to the water tubes to which they are welded, from their areas most remote therefrom are short enough to allow complete absorption by water within water tubes of all radiant heat impinging upon steam tubes 90 when the latter are empty of steam. The possibility of building up dangerous temperatures which might destroy the steam tubes 90 is thus obviated by the protection afforded them by the water tubes. On the other hand, however, the steam tubes 90, when steam is flowing therethrough in normal amounts and the water level is reduced in the water tubes to which they are welded, protect the water tube against destruction, which would otherwise be likely to occur because of the presence of insufficient saturated steam therein, the units being normally so designed (for obvious reasons of economy) that during ordinary operation at full steam flow the water level is at a very low point and almost the entire surface ofthe superheater thus rendered active, while the quantity of saturated steam generated is also reduced due to the small quantity of water present.

In Figures 15 to 1'7 inclusive another modification somewhat similar to that last described is shown, in which at the lower end of the assembly a similarly elongated combined wall block and header portion I60 is provided which serves as a cross header connecting the steam tubes Ill-I90 of the upper and lower units ZOO-200a respectively, in a manner analogous to the connection between units lll0-I Ulla provided by header H15 in the embodiment last described, although it will be appreciated that inthe present instance the steam is transferred directly through the hollow interior of element I60, which is located partly inside the combustion chamber and generally in a common plane with rather than outside the water wall.

The water inlet header I650 may be carried by and. on the back of the steam cross header I500 in similar fashion to the method of securing the upper water header to the backs of the aligned inlet and outlet headers H5, H6, as shown in Figure 17, in which View parts analogous to those previously described have been given like reference numerals with the addition to each of the letter 0. Detailed re-description is accordingly believed unnecessary. It will be understood that when the header assemblies are carried by the water wall tubes at both ends, as contemplated in this embodiment, the superheater assemblies may be of greater width. As indicated in Figure 16, their proportions might be such that they could not be fitted between the water tubes 280 by which the header block [600 is carried, and this embodiment is accordingly especially suited for use where the water wall tubes are spaced on unusually close centers.

Whichever embodiment of cross header is used, a drain for condensate is preferably provided, as at lTlb-ll'lc.

While it will be apparent that the illustrated embodiments of my invention herein disclosed are well calculated to adequately fulfill the objects and advantages primarily stated, it is to be understood that the invention is susceptible to variation, modification and change within the spirit and scope of the subjoined claims.

What I claim is:

1. In a boiler, in combination with saturated steam generating means and a source of water supply, a water wall structure including a plurality of spaced tubes arranged appurtenant a heating chamber, a water-regulated superheater comprising a tubular assembly extended at an angle to the horizontal across said heating chamber and having combined supporting and supply portions connected thereto and mechanically connected to the water wall'and also provided with coupling portions connecting them outside the chamber to said saturated steam generating means and said source of water supply, and assistingin holding the Wall structure against outward movement. j

I 2. In combination with a furnace having a combustion chamber and water walls bounding the same, said Water walls comprising a plurality of spaced tubes arranged in common planes spaced from each other across said combustion chamber, tubular heat absorbing elements of greater width than the spacing between said water wall tubes, said heat absorbing elements extending across the combustion chamber between spaced portions of saidwater walls, and

means supporting the tubular heat absorbing elements and for providing fluid conductive connection thereto through said water wall, comprising hollow supportingblock elements having pore 'tions thinned and extended through the spaces between said water wall tubes but elongated in the direction in which said tubes extend, coupling means connected to said thinned portions outside the water walls, said heat absorbing elements being connected to and supported by said elements inside the water walls.

3. In combination with a furnace having a combustion chamber and water walls bounding the same, said water walls comprising a plurality of spaced tubes certain of which are arranged in separate wall formations spaced from each other across said combustion chamber, tubular heat absorbing elements of greater width than the spacing between said water wall tubes, hollow supporting block elements having portions thinned sufficiently to extend and extended through the space between the water wall tubes but elongated in the direction in which said tubes extend, said block elements being opposedly arranged across the combustion chamber, and said heat absorbing elements being supported and connected to said block elements inside the water walls and extending across the combustion chamber at an angle to the horizontal, and coupling means outside the combustion chamber connected to said thinned portions of the block elements for providing fluid conducting connections thereto.

4. As a new article of manufacture, a shielding wall block for spaced generallyparallel water wall tubes and the like, said block having a face portion wider than. its rear portion and the latter adapted to extend between such tubes, the interior of the block having a hollowed chamber extending from said wider face portion through said narrower rear portion, said face and narrowed rear portions having coupling openings therein communicating with said chamber, for conducting fluid through the spaces between said tubes, the opening in the narrowed rear portion being elongated in the direction of extension of the tubes.

5. As a new article of manufacture, a shielding wall block for spaced generally parallel water wall tubes and the like, said block having a face portion wider than its rear portion, the narrower rear portion being adapted to extend between such tubes, the interior of the block being hollowed and the face of said block being provided with a plurality of openings between which the hollowed interior provides a communicating chamber which extends longitudinally of and between such tubes.

6. In combination with a furnace having a heating chamber through which gases of combustion may travel in a predetermined direction, a. water-regulated radiant superheater assembly extending across said heating chamber and across the path of gas travel at an angle to the horizontal, said assembly comprising alternated steam and water tubes and having a water tube along its edge first contacted by the gases, and a plurality of smaller steam tubes carried by and arranged to shield that surface of said Water tube which would otherwise be exposed to such gases, said smaller steam tubes being integrated to such surface whereby an unbroken heat bridge is provided between them and said water tube.

7. In combination with a boiler, a combustion chamber, walls bounding said chamber including a water wall comprising a plurality of spaced tubes, a water regulated superheater construction 7 the water wall tubes and being secured thereto at one extremity, and at the other extremity slidable therethrough.

8. In combination with a boiler, a combustion chamber, walls bounding said chamber including a water wall comprising a plurality of spaced tubes, a water regulated superheater construction including a plurality of substantially parallel tube assemblies extending across the combustion chamber at an angle to the horizontal, headers connected to said assemblies arranged outside said walls and connected to the assemblies through said spaced tubes, the assemblies being interspaced with relation to the tubes, and the portions extending between the latter being slidable with relation thereto at least at one end, the header portions overhanging the outside of said water wall to brace the same against explosion pressures.

9. Superheating apparatus as set forth in claim 8 in which said tube assemblies comprise alternate steam and water tubes welded together to form individual wall sections, and said wall sections are positioned within and across the combustion chamber with their, general planes parallel to the direction of gas travel.

10. Superheating apparatus as set forth in claim 8 in which said tube assembliescomprise alternate steam and water tubes welded together to form individual wall sections, and said wall sections are positioned within and across the conducted transversely through the spaces between said water wall tubes. 7

11. In combination with a boiler, a combustion chamber, water walls bounding said chamber including a plurality of spaced water wall tubes lying substantially parallel to the direction of travel of heated gases from the combustion chamber, anda water-regulated superheater construction including a tube assembly extending across thecombustion chamber at an angle to the horizontal, steam and water headers connected to the ends of said tube assembly, the tubes of said assembly comprising superheating steam tubes and water-regulating tubes'metallically integral with each other and arranged in generally 00- planar relation, the planes of said assemblies being substantially parallel to the paths of gas travel, and means for conducting fluid to and from the tubes of said 'superheater .assembly transversely through the spaces between said water wall tubes.

12. In a boiler, in combination with saturated steam generating means and a source of water supply, a water wall structure including a plurality of spaced tubes arranged appurtenant a heating chamber, a water-regulated superheater comprising a tubular assembly extended at an angle to the horizontal across said heating chamber and having combined supporting and supply portions connected thereto and mechanically connected to the water wall to assist in bracing said water wall structure, and also to support said assembly, said portions being reduced in width in their parts extending through the spaces between the water wall tubes.

13. Heat absorbing apparatus comprising in combination with a plurality of spaced tubes ar-' ranged around a substantially enclosed area, tubular heat absorbing elements of greater width than the spaces between saidtubes and'extending across said area,and coupling portions for said elements having portions of reduced width to allow their projection, and being projected, through the spaces between said tubes, and portions carried by said coupling portions outside and overhanging the backs of said tubes to brace the same against outward movement.

14. Heat absorbing apparatus comprising in combination with a water wall portion including a plurality of spaced tubes arranged around a' chamber, tubular heat absorbing elements extending across said chamber and having connecting portions projected through the spaces between said tubes, and being carried by said Water wall portions and provided withholding means to assist in the bracing-of said water wall portions.

15. Heat absorbing apparatus comprising in combination with a plurality 'of spaced tubes'arranged around a substantially enclosed area, tubular heat absorbing elements extending across said area and having connecting portions projected through the spaces between'said tubes, and portions carried by said connectingportions outside and overhanging the backs of saidtubes to brace the same against outward movement, the connecting portions and said elements being supported by the tubes.

CHARLES S. TURNER.

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