US2288948A - Boiler - Google Patents

Description

July 7, 1942.

c. W. GOOD BOILER Filed March 4, 1940 5 Sheets-Sheet 2 ZFzvenr gigarzes WG-ood V CMAW,

July 7, 1942. c. w. soon- BOILER Filed March 4, 1940 3 Sheets-Sheet 3 Patented July 7, 1942 BDILER Charles W. Good, Erie, Pa., assignor to Weil- McLain Company, Erie, Pa., a corporation of Delaware Application March 4, 1940, Serial No. 322,111

12 Claims. (Cl. 122 209) This invention relates to improvements in boilers and more particularly concerns a boiler adapted for domestic heating purposes.

An object of the invention is to provide an improved boiler having a novel arrangement and assembly of body panels defining the combustion chamber or fire-box of the boiler and having internal passages for water to be heated.

Another object of the invention is to provide in a boiler of this kind body panels each embodying an internal arrangement of connected circulating passages which intercommunicate in the boiler assembly to form a complete circulation system of high thermal efficiency.

A further object of the invention is to provide a, boiler having the foregoing general characteristics and which may be varied as to size and capacity merely by changing certain of the panels without structural alteration of other parts of the boiler unit.

Still another object of the invention resides in the provision of improved means for securing the panels of the boiler into a rigid unit.

A still further object of the invention is to provide a novel arrangement of auxiliary heat transfer members in the boiler forming a part of the circulation system embodied in the walls of the boiler.

Yet another object of the invention is to provide a boiler of this kind which is readily adaptable for solid or fluid fuel, is compactly constructed of easily assembled cast sections and has high heat transfer efficiency.

Other objects and advantages will become apparent in the following description and from the accompanying drawings in which:

Figure 1 is a perspective view of a boiler embodying the features of the invention.

Fig. 2 is a vertical sectional view through the boiler taken substantially in the plane of line 2-2 of Fig. 1.

Fig. 3 is a sectional plan view through the boiler taken substantially in the .plane of line 3-3 of Fig. 1.

Fig. 4 is a perspective view with certain parts broken away showing a slightly modified form of boiler embodying the invention.

Fig. 5 is a vertical sectional view taken substantially in the plane of line 5-5 of Fig. 4, but additionally showing a modified top construction.

Fig. 6 is a sectional plan view through the top of the boiler taken substantially in the plane of line 66 of Fig. 4.

Fig. 7 is a fragmentary vertical sectional view through a boiler of the present type showing. auxiliary heat transfer members in end eleva tion.

Fig. 8 shows the heat transfer elements of Fig. '7 in side elevation, partially in section for better illustration of details.

Fig. 9 is a fragmental vertical sectional view through a modification of the boiler shown in Fig. 4.

Fig. 10 is a horizontal sectional view taken substantially on the plane of line 10-10 of Fig. 9.

Fig. 11 is a perspective view of the base panel section used in the form of boiler shown in Figs. 4 and 9.

Fig. 12 is a vertical sectional view through the base panel section taken in substantially the plane of line I2-l2 of Fig. 11.

While the invention is susceptible of various modifications and alternative constructions, I have shown in the drawings and will herein describe in detail the preferred embodiments, but

it is to be understood that I do not thereby intend to limit the invention to the specific forms disclosed, but intend to cover all modifications and alternative constructions falling within the spirit and scope of the invention as expressed;

in the appended claims.

According to the present invention the body: of the boiler is constructed of a plurality of panel sections, preferably made of cast iron,

secured together to form a box-like enclosure serving as the fuel combustion chamber. The panel sections of the fire-box or combustion chamber, and in certain instances the bottom or base structure below the combustion chamber, are formed with individual internal systems of passages for water circulation. Such circulation passages are preferably small in crosssectional area to insure rapid circulation and to avoid excessive internal pressure, but are of ample total capacity to accommodate the required volume of water. The circulation systems of the individual panel sections are connected together and the resulting circulation system is one of high thermal efliciency. Within limits the dimensions and heating capacity may bechanged simply by substituting differently dimensioned panels for certain of the wall panels without altering any of the remaining structure of the boiler. Additional heat transfer capacity may be secured by equipping the boiler with auxiliary heat transfer units occupying part of the space in the combustion chamber and communicating with the circulation system through the passages in one or more of the body panels.

In Figs. 1 to 3 is shown an exemplary form of the invention providing a dry base boiler unit. This boiler includes a plurality of generally flat cast iron panel sections including spaced parallel upright side wall panels I5. upright front and rear Wall panels l6 and I1, respectively, and a horizontal top panel structure, generally identified by the numeral IB, supported by the wall panels. The several wall and top panels are joined together rigidly to form a fire-box or combustion chamber l9 which may have a grate (not shown) therein if the boiler is to be fired with solid fuel such as coal, and which will accommodate suitable burner equipment if fluid fuel, such as oil or gas, is to be used.

Each of the side wall panels I and the rear wall panel I! is generally similar in construction and each includes a plurality of longitudinally extending, closely spaced parallel tubular water passages connected at their upper and lower ends by tubular header passageways 2| and 22, respectively. Between each pair of adjacent, longitudinal tubes 20 is a narrow solid web 23, the Webs and the tube walls being so proportioned that heat will be transferred efficiently to the water in the panel circulation system. By having each of the panel circulation systems divided into a multiplicity of passages of small flow areas high resistance to internal pressures is developed within the panels. Moreover, the small flow areas of the passages assures rapid circulation of water therethrough in the operation of the boiler, thus enhancing thermal efficiency by improved heat absorption and tending to maintain the walls of the boiler relatively cool.

The front wall panel I 6 is provided with a circulation passage system similar to that of the side and rear wall panels, but has therein an upper fuel or access opening 24 and a lower cleanout opening 25 which necessitate some modification of the arrangement of passages.

Thus, extending in spaced parallel relation longitudinally of the panel l6 between the openings is a plurality of tubular passages 21 connected at their lower ends by a horizontal bottom header 28 located immediately above the lower opening 25. At their upper ends the passages 2! are connected by a top header 29 which preferably completely encircles the upper opening 24. Suitably hinged doors 3% and 3| may be furnished to close the upper and lower openings 2'4 and 25, respectively.

In the dry base construction, the bottom headers 22 of the side and rear wall panels and the bottom header 28 of the front wall panel are located in a common horizontal plane spaced upwardly from the lower edges of the panels at approximately the lower level of the combustion chamber. Those portions of the panels which are below the bottom headers may be of a solid, rib-reenforced construction. Means, such as bolts 32 may be employed to secure the adjacent edges of the lower solid portions of the panels together.

Feed water for the boiler is supplied to the bottom headers 22 and 28 of the wall panels through one or more ducts 33 which need oommunicate with only one of the headers, herein the rear wall bottom header which in turn communicates as a distributor with the remaining bottom headers. As shown, there are two of the feed water ducts 33 which are respectively contom headers.

nected with the opposite end portions of the distributor header. Such means as push nipples 34, connect the rear ends of the side Wall headers 22 with the opposite ends of the distributor header. Similarly, the front wall bottom header 28 communicates at its opposite ends with the forward ends of the side wall headers. Thus, there is full uniform distribution of the feed water to all of the panels through the distribution system provided by the connected bot- For the convenient accommodation of the nipples 34. the wall panels may be provided with coaxial annular bosses 35 at the respective ends of the bottom headers.

From the headers 22 and 28 the water rises through the respective circulation passages 20 and 21 of the panels into the respective top headers 2| and 29. Thence, the Water is delivered into the hollow top structure it of the boiler through suitable connecting push nipples 37. Such push nipples are received at their lower ends within bosses 38 that open upwardly from the center of each of the top headers. At their upper ends the nipples 37 are received within central, downwardly opening bosses 32 formed at the edges of a horizontal top panel section 40 which constitutes the crown sheet of the top structure E8. The water from each of the wall panels enters the adjacent one of the respective legs of a marginal header 4! within the crown sheet 40 and passes from such header into a series of parallel, tubular circulation passages 42 herein shown as extending in a front to rear direction and traversed by a central header 43. Between certain portions of the passages 42, herein those portions rearwardly of the central header 43, the intervening spaces are closed by webs 44 (Figs. 2 and 6). On the other side of the central header the intervening spaces are open slots 45 which in effect provide a grille through which the rising products of combustion escape.

Hollow upward prolongations of the nipple bosses 39 (Figs. 1, 5 and 6) at the opposite sides of the crown sheet panel 45 are suitably connected as by push nipples 47 with downwardly opening push nipple bosses 48 formed at the sides of a similarly dimensioned horizontal panel section 49 which surmounts the panel 45 in spaced parallel relation and serves as the cap sheet of the top structure 13. Within the cap sheet panel 49 a relatively large transverse header 50 connects the push nipple bosses 48 to conduct heated water to one or more take-off ducts 5|. The cap sheet may also include a series of tubular passages 52 extending in spaced parallel relation to opposite sides of the header 53 and communicating with headers 53 (Fig. 2) located at the front and rear ends of the cap sheet panel.

The crown sheet panel 46 and cap sheet panel 49 are mounted in spaced relation to provide an economizer chamber 54 which is enclosed by vertically cooperating marginal flanges 55 and 51, respectively. Thereby, the flue gases escaping through the grille slots 45 are confined in heating relation to the top panels. The spent gases pass off at the rear of the economizer chamber into a flue 58 which communicates therewith through an opening 59 in the flanges 55 and 51. At the front of the chamber 54 the flanges 55 and 51 have a cleanout opening glllerein which is closed by a suitable hinged door The Wall panels and top structure It are suitably connected into a rigid unit as by means of bolts 62 which are fastened through integral projections herein formed as horizontal flanges 63 and 64 extending in spaced parallel relation laterally outwardly from the wall panels and the crown sheet panel 46 adjacent to the nipple bosses 38 and 39, respectively. At the sides of the boiler, the bolts 62 are longer and at their upper ends engage horizontal wing flanges 65 which project from the cap sheet panel 49 parallel to the underlying flanges 63 and 64.

A wet base boiler may be constructed substantially like the dry base boiler just described, including the identical top structure l8 and having the same side wall panel construction surrounding the combustion chamber. However, in the wet base boiler (Figs. 4 and 5) the side wall panels l5 and front and rear wall panels I6 and II, respectively, are modified to have continuations of the upper circulation passages in the lower portions thereof and are supported in communication with the interior of a wet base panel member 66.

The lower portions of the side and rear wall panels I5 and I1 have horizontal base headers 61 which communicate through a series of spaced parallel vertical circulation passages 68 with intermediate horizontal headers 22 which correspond to the bottom headers 22 of the described dry base boiler. At substantially the center of each of the base headers 61 communication is suitably eiiected through a, downwardly opening annular boss 69 and a push nipple 10 with the interior of the base 66. A similar nippled connection between the base 66 and the interior of the front wall panel I6 is effected through a passage H which surrounds the cleanout door opening 25 in this panel and communicates above the opening with the remaining front wall circulation passages.

Feed water is delivered into the base panel 66 through one or more feed water ducts 33 (Figs. 5, l1 and 12) which open into a horizontal distributor header 12 in the present instance formed within a foot flange 13 provided along the rear edge of the base. Communicating with the header I2 is a series of spaced parallel circulation passages 14 which extend in a front to rear direction through the base panel and are connected at their front ends by a horizontal front header 15. A transverse header l1 traverses the passage 14 from side to side of the base and communicates with the nipple connections for the side wall panels 15.

For securing the several wall panels and the base panel 66 rigidly together, spaced parallel horizontal projections in the form of wing flanges 18 and 19 (Figs. 4, 5 and 12) are provided centrally along the lower edges of the wall panels and along the edges of the base panel, respectively, to receive securing bolts 89. Leg flanges 8| at the front corners of the base 66 may be provided to cooperate in supporting the base in spaced relation above the floor.

For fluid fuel firing a boiler embodying the invention may be constructed by combining the wet base panel 66 and certain features of the dry base boiler shown in Figs. 1 and 2. In such a construction, the base panel 66 is modified to resemble the crown sheet panel 46 in that it s has added thereto relatively high marginal flanges which may be of approximately the width of the crown sheet panel flanges 55. These high marginal flanges are designed to take the place of the solid rib-reenforced lower structure of the vertical wall panels in Figs. 1 and 2, the lower edges of the vertical panels terminating for this purpose immediately below the connected bottom headers 22 and 28 and being fashioned to cooperate with the respective upper edges of the base panel flanges. ater circulation from the base panel 66 to the vertical wall panels can be established by connecting the base panel nipples 10 at opposite sides thereof into appropriately cored nipple bosses 66 with which the lower edges of the modified side wall panels l5 may be equipped. Where the boiler is to be used in the dry base form as shown in Figs. 1 and 2, the nipple bosses 66 may of course be omitted. Adequate room is thus provided between the lower edges of the modified vertical wall panels and the base panel for various accommodation passages and openings for the burner equipment. This arrangement also afiords an ample chamber within the boiler for efficient combustion. An advantage of the modification just described is that the same pattern and core equipment as used for the vertical panels of the form of Figs. 1 and 2 may be used for the modified vertical walls rather than requiring an alternate set of,

vertical panel patterns as for the form of the invention shown in Fig. 4.

According to the present invention, it is possible to vary the dimension and capacity of either the dry base or the wet base form of the boiler simply and economically merely by an optional exchange of wall panels without otherwise altering the construction. In both forms of the boiler as seen in Fig. 3 and Figs. 4 and 5, respectively, the boiler width equals the front and rear wall panel width, the side wall panels lying in edgewise engagement between the front and rear wall panels. To increase the boiler width, therefore side wall panels 82 (Figs. 9 and 10) are substituted. These substitute panels are of greater width so as to receive the front and rear wall panels in edgewise abutment against the inner faces thereof, and thus increase the width of the boiler by substantially the combined substitute panel thicknesses. Due to their greater width, the substitute panels 82 can be formed with a larger number of Water passages and correspondingly increase the capacity of the boiler. A single pattern may serve the purpose for casting bath of the substitute panels 82, and this is the only different equipment required for making the increased capacity boiler. For brevity in illustration the wet base form of boiler has been chosen to illustrate the mounting of the substitute panels 62 in Figs. 9 and 10, although it will be understood that such panels may with suitable adaptations be imilarly mounted in the dry base form.

For effecting a closed joint with the crown sheet panel 40 and base panel member 66, each of the substitute panels 82 has upper and lower inwardly projecting flanges or ledges B3 and 84, respectively formed longitudinally along the top and bottom margins thereof. Each of these ledges is shorter than the width of the panel and has the opposite ends thereof offset from the front and rear edges, respectively, of the panel sufilciently to lie between the front and rear wall panels in the boiler assembly and bear against the crown sheet panel and the base panel membar while the main body of the substitute panel overhangs the side of the base member.

Water circulating connections for each of the substitute panels 62 with the crown sheet panel 40 i effected through an upwardly opening passage'or mouth 85 in the upper ledge 83 which communicates with upper header 2| of the panel and receives the crown sheet push nipple 31. Similarly, circulation connection with the base member 665 is effected through a downwardly opening passage or mouth 8! in the base ledge 84 which receives the base push nipple it and communicates with the base header El of the associated substitute panel. For securing the substitute panels 82 rigidly to the base member 66, stud bolts 83 pass through the wing flanges T9 of the base member and are threaded into the lower ends of the panels, while to secure the panels to the crown sheet panel 40 similar stud bolts 88' pass through the wing flanges 64 and are threaded into the upper edges of the panels 82. For use in the dry base boiler, the base ledges 8d of the substitute panels may of course, be omitted and suitable water circulation connections provided for effecting communication with the lower headers of the dry base front and rear wall panels. Thus, in either the dry or wet base forms of the boiler the optional side panel constructions require no changes in the remaining features of the boiler.

For solid fuel it may be desired to provide a conventional shaker grate, generally indicated at 90 (Figs. 4 and 5), which may comprise a plurality of cooperative rockable grate bars 9| journaled in the front and rear walls of the boiler at about the level of the headers 22 thereof. In the present instance each of the side wall panels l5 has an inwardly projecting series of grate studs 92 cooperating with the side grate bars 9! and serving as a continuation of the surface of r the grate. To shake the grate, the grate bars may be rocked in the usual manner through an operating shaft 93. projecting from the front of the boiler. In this arrangement the space below the grate 9i! forms the ash pit, the bottom of which is defined by the base panel member 65. The feed water in those portions of the panel structure which define the pit will be preheated by such heat as finds its way down from the combustion chamber.

Greater water capacity may be secured in either the dry base or wet base forms of the boiler by increasing the number of horizontal panels in the top structure it. As shown in the modified form of Fig. 5, an internally channeled and marginally flanged panel 89 constructed generally like the crown sheet panel iii and the cap sheet panel it may be suitably nippled into the top circulation system intermediate the latter panels. In this arrangement, the grille slots 43 for upward passage of the combustion gases are formed in the rear part of the crown sheet panel 43 while the intermediate panel 8;) is formed with similar grille slots (not shown) in the forward half thereof. Thus, the combustion gases entering the top structure It must pass in one direction, for example, from rear to front, through a first economizer chamber 54*, and then in the opposite direction through a second economizer chamber 54 before exhausting through the flue opening 59.

Since all of the horizontal panels, including the cap and crown sheet panels 69 and 4B, the intermediate top panel 39, and the base panel E56, are preferably dimensioned substantially alike and have similar fluid passages therein, the same pattern equipment may be used in casting them, the necessary changes as to external flanges or nipple bosses being easily effected by means of removable and interchangeable pattern elements auxiliary to the main or body pattern. As a result, the cost of patterns for manufacturing the present boiler is exceptionally moderate.

Substantially increased capacity and greater circulation of the water may be had in the pres ent boiler by the provision of auxiilary heating units connected in water circulating communication with certain of the wall panels and located within the upper part of the combustion chamber to be heated by the upwardly passing flue gases. As shown in Figs. 2 and 3, the auxiliary heating units may take the form of flattened, chambered castings located adjacent to the side wall panels iii of the boiler and one or more similarly constructed intermediate chambered castings Q5 in spaced parallel relation between the side units. The side auxiliary units 95 in the present instance communicate with certain of the vertical side wall circulation passages 20 through the medium of push nipple connections ill, while the intermediate auxiliary units 96 are connected by push nipples 92 with certain of the vertical rear wall flow passages 23. To secure the several auxiliary heating units in place, they may be provided with attachment flanges 99 which are suitably secured to the rear wall panel il' as by means of bolts mil.

In another form of auxiliary heating means as seen in Figs. '7 and 8, a horizontal series of spaced parallel finned units fill may be secured to project cantilever fashion from the rear wall panel of the boiler across the interior of the combustion chamber to be swept by the upwardly passing flue gases. Each of the finned units may be formed of cast iron and comprises an elongated upper tubular body or core W2 and a similar tubular body or core H33 in spaced parallel relation therebelow. Each of the cores I02 and M3 has a longitudinal series of laterally projecting spaced parallel heat transfer wings or fins the cast thereon. At the rear end thereof, each core of the finned units may be connected by means such as a push nipple use into communication with one of the vertical circulation passages in the rear or supporting wall of the boiler. At the front ends, the cores H62 and H33 may be nippled into the opposite or front wall of the boiler or they may, as shown, be connected together for water circulation therethrough by a hollow header plate Iii? with which communication is efiected as by push nipples use. These finned units are of high heat transfer efficiency due to the large heating area of the fins and cores.

From the foregoing it will be apparent that the present invention provides an improved, economical boiler construction of high thermal efiiciency and large capacity in a compact, small size and easily assembled unit. The unique, interconnected circulation systems of the boiler panel structure provide combined circulation system of high efficiency. Due to the small cross-sectional flow areas and tubular structure of the several flow passages within the boiler panels internal pressures are kept to a safe, well distributed minimum. Either a dry base or a wet base installation can be provided, and the size and capacity of either such form of the boiler may be optionally altered merely by substitution of certain of the wall panels. Further increased capacity can also be attained by equipping the boiler with auxiliary heat transfer units.

I claim as my invention:

1. A boiler comprising, in combination, a plurality of upright wall panels connected together in a box-like arrangement to provide the combustion chamber of the boiler, a system of water circulation passages in said panels, means for feeding water into said passages, a crown sheet panel supported by the upper edges of said wall panels in enclosing relation to said chamber and having an opening therein for escape of flue gases from the chamber, an upstanding marginal flange around said crown sheet panel, a cap sheet panel surmounting said crown sheet panel in spaced relation and having a downstanding marginal flange complementary to and engaging said upstanding flange to enclose the space between the latter panels and provide a flue gas chamber, interconnected circulation passages within said crown sheet and cap sheet panels communicating with said wall panel passages, and means communicating through said flanges for withdrawing spent gases from said flue gas chamber.

2. A boiler having, in combination, a pair of upright panels of substantially the same height and width dimensions mounted in spaced faceto-face relation, a top panel structure connected with said upright panels, said top panel structure and said upright panels being adapted to receive either a pair of upright end wall anels positioned wholly within the confines of the margins of the first mentioned upright panels and the top panel structure or, optionally, a larger pair of upright end wall panels positioned in face abutment with the edges of said first-mentioned upright panels and top panel structure, and means for connecting the optional end wall panels to said first mentioned upright panels and the top panel structure.

3. A boiler comprising, in combination, quadrangular top and base members; front and rear wall panels of substantially the same width as said top and basemembers mounted vertically at the front and rear margins, respectively, of said top and base members; and a pair of side wall panels mounted with the side margins thereof abutting the side edges of said front and rear wall panels and having inwardly projecting integral flanges at the upper and lower ends thereof engaging the inner side margins of said top and base members, said flanges being shorter than the width of said side wall panels sufliciently to fit in assembly between said front and rear Wall panels.

4. A boiler of the character described comprising, in combination, quadrangular top and base members similarly dimensioned as to width and depth, a pair of spaced parallel vertical wall panels mounted upon opposite margins of said base members in support of said top member and being of a width substantially coinciding with the lengths of the associated margins of the top and base members, a pair of additional wall panels of a Width corresponding to the lengths of the remaining margins of said top and base members and being mounted in face abutment with the side edges of said first mentioned panels, inwardly projecting marginal flanges along the upper and lower ends of said additional panels engaging the adjacent margins of said top and base members, said top and base members and said additional panels having passages therein for fluid circulation, and means for connecting all of the passages in fluid circulation communication through said inwardly projecting marginal flanges.

5. A boiler comprising, in combination, a quadrangular top structure including a plurality of panels having an interconnected system of circulation passages therein, a pair of spaced parallel upright panels in edgewise engagement with said top structure and of a Width substantially the same as the corresponding top structure width, fluid passages in said upright panels communicating through the upper edges thereof with said top circulation system, and an additional pair of upright panels in facewise engagement with the first mentioned upright panels and each having an inwardly projecting ledge to engage the respective adjacent inner marginal surface of the top structure, said additional panels having fluid passages therein communicating with said top circulation system through said ledges.

6. A boiler of the character described including, incombination, a plurality of wall panels arranged to define a combustion chamber and having a system of internal circulation passages, a plurality of flattened generally upright hollow heat transfer units formed separately from said panels extending in spaced relation across at least a portion of the interior of the chamber, and means adjacent to the upper and lower edges of said heat transfer units extending between the units and one or more of said wall panels for connecting said heat transfer units in direct circulation communication with said passages.

7. A boiler construction having, in combination, a plurality of generally rectangularly shaped panels arranged to be connected in vertical edge-to-edge relation to form a box-like enclosure constituting the combustion chamber of the boiler, each of said panels having a series of spaced vertically extending fluid passages therein and upper and lower horizontal header passages in communication with the Vertical passages, means for establishing communication between the lower header passages of the several panels, means for introducing fluid to be heated into the lower header passages through one of the panels, a top structure including a horizontal panel forming the top of the combustion chamher and resting upon the upper edges of said vertical panels, said horizontal panel having fluid circulation passages therein, and a connecting member extending vertically between said horizontal panel and one of the upper header passages for circulation of fluid upwardly from such header passage into the passages in the horizontal panel.

8. A vertical boiler comprising, in combination, a plurality of vertical wall panels having fluid circulation passages therein, opposed vertically spaced horizontal panels also having fluid circulation passages therein, said vertical panels resting at their lower edges upon the upper face margins of the lower of the horizontal panels and at their upper edges supporting the upper horizontal panel which lies superimposed on such edges, and means connecting the panels together to define a fully enclosed combustion chamber, the circulation passages of all of said panels intercommunicating to form a complete circulation system for heating fluid, said horizontal panels being basically similar in shape and dimensions to permit casting thereof from one basic set of patterns.

9. A boiler construction of the character described comprising, in combination, opposed pairs of vertically arranged flat panels defining the fire-box of the boiler, each of said panels having an individual internal fluid circulation passage system including vertical fluid passages and horizontal upper and lower headers, the upper headers lying close to the top edges of the respective panels, nipple connections between the ends of the lower headers of the panels connecting all of the individual circulation system together, a top panel supported at its margins by the upper edges of said vertical panels and having a system of interconnected circulation passages thereln, and means connecting said upper headers in communication with the circulation system of said top panel, the ends of said upper headers being unconnected so as to leave the adjacent side edges of the vertical panels free for relative movement to accommodate expansion of said top panel.

v10. In combination in a boiler construction of the character described, a plurality of vertical fiat panels cooperating edgewise to define a tubular structure forming the fire-box chamber of the boiler, each of said panels having an individual internal circulation system including horizontal headers adjacent to the upper and lower edges of the panel and a plurality of vertical fluid circulation passages connecting said headers, a base panel supporting the lower edges of said vertical panels and having a system of fluid circulation passages therein, a top panel supported marginally by the upper edges of said vertical panels and enclosing the fire-boxchamber, means for introducing fluid to be heated into said base panel, and vertical nipple connections between intermediate points of the upper and lower headers of the vertical panels and the top and base panel circulation systems, respectively, the cooperating side edges of said vertical panels remaining unconnected to permit relative movement responsive to horizontal expansion of said top or base panels.

11. In combination in a boiler construction of the character described, a set of upright panels arranged to provide a box-like enclosure defining a combustion chamber, each of said panels having a system of water circulation passages therein, means for connecting the individual systems of passages of the panels in circulating communication adjacent to the lower end of the combustion chamber, a crown sheet panel closing the top of said chamber and supported by the upper edges of said upright panels, said crown sheet panel having an internal circulation system including a header intermediately dividing this panel and a plurality of spaced circulation passages communicating with the op,- posite sides of the header, said crown sheet panel having openings between said circulation passages at one side only of said header providing a grille for upward escape of products of combustion from said chamber, a cap sheet panel in substantially spaced relation above said crown sheet panel and having a system of water circulation passages therein communicating with said header, means for withdrawing heated water from said cap sheet panel, and means extending between the margins of said crown sheet panel and said cap sheet panel to enclose the space therebetween for confining the products of combustion which travel up through said grillein heat transfer relation to said panels, said enclosing means having a flue opening at the side of the heat transfer space between the panels farthest removed from said grille.

12. A boiler having, in combination,'a pair of,

upright panels mounted in spaced face-to-face relation, a top panel connected'with said upright panels, said top panel and said uprightpanels being adapted to be assembled into a boiler unit optionally with a pair of spaced end wall panels confined wholly within the margins of said firstmentioned upright panels and top panel or in face abutment with the end edges of said upright panels and said top panel to provide optional boiler units of different capacities, and means for connecting said end wall panels to said first-mentioned panels and to the top panel.

CHARLES W. GOOD.

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