US2709991A - Boiler - Google Patents

Description

June 7, 1955 H. w. WIEGAND BOILER 2 Sheets-Sheet 1 Filed March 30, 1954.

- INVENTOR 3r 6/I AP0MWF 4N0 ATTORNEYS:

June 7, 1955 H. w. WIEGAND 2,709,991

BOILER Filed March 50, 1954 2 Sheets-Sheet 2 INVENTOR BY amwaW/fisenma fee 1 ATTOR EYS.

BOILER Howard W. Wiegand, Palisades Park, N. 3.

Application March 30, 1954, Serial No. 419,944

1 Claim. (Cl. 122-268) (Granted under Title 35, U. S. Code (1952), see. 266) The invention described herein may be manufactured and used by or for the Government of the United States of America for governmental purposes without the payment of any royalties thereon or therefor.

This invention relates to boilers and more particularly to smaller boilers that are subject to minimum corrosion, permit only minimum sedimentation, that are compact, provide increased heat transfer surface in the path of the combustion gases as the latter pass through the water or steam, and are easily cleaned or repaired.

Smaller size boilers that are currently being used for generating hot water or steam do not afford sufficient heat transfer surface, in proportion to their size, between the hot gases generated by the fuel combustion and the water in the boiler. In these boilers the hot gases pass only once or twice across heat transfer surfaces that separate the hot gases from the water to be heated. Only a small fraction of the available heat energy is derived by the water from the hot gases because of ineiiicient design for heat transfer. This represents a considerable waste of fuel since much of the heat energy made available by combustion of the fuel is lost through delivery of high temperature gases to the chimney. Partially, this is a result of the arrangement of the boiler tubes. Furthermore, in the smaller boilers in current use the percentage of total surface in the path of the hot gases between the fire box and the chimney that is eifective as heat transfer surface is too small thereby limiting the boiler rating. in addition, an important consideration in the construction of boilers aside from the problem of eiiicient heat exchange and one that is often ignored in small boiler construction is the need for an arrangement whereby stagnant water pockets in the boiler are eliminated so that corrosion and sedimentation are minimized.

This invention marks a departure from the prior art in that it provides a boiler of simple efiicient construction. It includes a series of fire tubes each of which is supported concentrically within a corresponding series of water tubes. Each of the tire tubes and each enveloping water tube is secured to the sides of the boiler at a predetermined angle to the horizontal, thereby permitting improved circulation. In addition, the sides of the boiler hereinafter referred to as headers are joined at or near their lower ends by tubes for permitting water circulation. The combination of the latter and the tilted tube arrangement provides for improved water circulation and the virtual elimination of stagnant water pockets in the boiler. Consequently, corrosion and sedimentation are minimized. Furthermore, the tubes are arranged for easy access whereby cleaning and repair is facilitated.

An object of this invention is to provide a boiler.

A further object is to provide an improved boiler for generating water or steam.

A further object is to provide a boiler of the class known as tubular boilers, that is light in weight, compact, eificient, and characterized by large heat transfer surface area.

Patented June 7, 1955 A further object isto provide a boiler of the class known as tubular boilers for generating steam or hot Water and including provision for rapid circulation of the water adjacent the heat transfer surfaces of the boiler.

A further object is to provide new and useful improvements in hot water boilers of the multitubular type.

A further object is to provide new and useful improvements in hot water boilers of the multitubular type which are characterized by increased heat transfer surface and increased water circulation while consuming a minimum amount of fuel and which are further characterized by overall simplicity of construction and compactness.

A further object is to provide a boiler which is characterized by large'heating surface, maximum water circulation, and a minimum fuel consumption.

Other objects and many of the attendant advantages of this invention will be readily appreciated as the same becomes better understood by reference to the following detailed description when considered in connection with the accompanying drawings wherein:

Fig. l is an exploded perspective view of a boiler, partly in section, according to a preferred embodiment of this invention, and

Fig. 2 is a longitudinal section of the boiler shown in Fig. 1.

Referring to Fig. l and Fig. 2, the boiler 10 includes a pair of headers 12 and 14. The header 12 is bounded by an outer tube sheet 16 and an inner tube sheet 18. The opposing header 14 is bounded by an outer tube sheet 22 and an inner tube sheet 24. The width of the tube sheets 16, 18, 22, and 24 are equal. The inner tube sheets 13 and 24 are rectangular and are substantially identical. The outer tube sheets 16 and 22 are longer than the inner tube sheets and are curved at the upper ends thereof as shown at 26. The pair of tube sheets bounding each header are joined in parallel spaced relationship by narrow lengths of boiler plate as shown at 28.

The headers 12 and 14 are joined to one another by means of a pair of crown sheets 32 and 34. The crown sheet 32 is sealed to the inner tube sheets 18 and 24. The crown sheet 34 is sealed to the outer tube sheets 16 and 22. The crown sheet 32 may be arched slightly between the tube sheets 18 and 24 for increased strength. The portion of the boiler between the crown sheets 32 and 34 is known as the dome. A boiler outlet for hot water or steam is provided in the crown sheet 34 by a pipe part of which is shown at 35.

Each of the tube sheets is formed with a plurality of openings; each of the openings of the several tube sheets is adapted to have secured and sealed therein one end of a boiler tube. Most of the openings formed in'the tube sheets 16 and 22 are adapted to receive the ends of the fire tubes 33 and most of the openings in the tube sheets 18 and 24 are adapted to receive the ends of the water tubes 36. Each concentric pair of tubes comprising a Water tube 36 and a fire tube 38 requires four aligned openings, one in each of the tube sheets 16, 18, 22, and 24. The concentric pairs of tubes are arranged at an angle to the horizontal plane defined by the bases of the two headers 12 and 14 to improve water circulation. Each opening 42 in tube sheet 16 is larger than each opening 48 in tube sheet 22. Gne end of each fire tube 38 is secured in an opening 42 in tube sheet 16 and the other end of each fire tube 38 is secured in an opening 48 in tube sheet 22. The reason behind the enlarged openings 42 is to provide for removal and replacement of water tubes 36 when the latter develops a fault such as a crack or leak. By first detaching and removing the fire tube 38 through the opening 42 it is then possible to remove the corresponding water tube 36 through the same opening 42. Because the methods of detaching and removing boiler tubes are well established, details are 3 omitted. Each enlarged opening 42 receives the enlarged end of a fire tube 38. The latter is sealed into the opening 42 of the tube plate id. The openings in the four tube plates are arranged in a staggered pattern (see Fig. l) to cause the hot combustion gases to follow circuitous paths in flowing upward from the firebox.

Bridging the header 14 adjacent the upper end thereof is, at least, one bridge pipe 54. The bridge pipe 54 is sealed into a pair or" horizontally aligned openings 56 and 58 formed in the two tube plates 22 and 2 The bridge pipe 5 2- permits the hot combustion gases to pass from the space within the boiler occupied by the boiler tubes on the way to the inside of the fire tubes 38, as indicated by the flow lines shown in Fig. 2.

A plurality of pairs of axially aligned openings, each pair includins an opening 62 and an opening 64 of equal diameter are formed in the outer tube sheet 16 and 22 in a horizontal plane above the crown sheet 32. Horizontally disposed fire tubes 66 are sealed into the open ings 62 and 64. The fire tubes 66 present channels to permit the flow of hot combustion gases after they have left the fire tubes 3% and are on their way to the srnok pipe 68.

Secured to the outer surlace of the outer tube sheets 16 and 22, are removable recessed closures 72 and 74. Both removable closures 72 and '74 are substantially rectangular and provide an air tight chamber on the outside of each of the tube sheets 15 and 22 which enclose the open ends of all the fire tubes 38. Guide means for the closures may be provided as at '73. The guide means 73 are suitably formed or secured by welding or the like. The closure 72 also covers the open ends of the fire tubes 66 while the closure 74 also covers the open end of the bridge pipe 54. The fastening means for the closures 72 and 74 are not shown on the drawing since conventional fastening arrangements, for example bolts, sufiice. The closure 72 includes a hinged door generally shown at 75 for easy access and inspection. The door 75 is secured by means of lugs, dogs or their equivalent.

The door '75 permits frequent cleaning of the fire tubes 33 to free them of accumulated soot. Since the soot acts as a heat insulator, the more frequently it is removed, the more efficient the operation of the boiler. Whenever the boiler is shut down for a period that is long enough to permit the structural elements to cool down, it is possible to open the door 75 and force a fire tube cleaning brush into and out of each fire tube 38 to quickly remove the insulating deposit of soot.

Connecting the lower ends 8'2. and S4 of the headers 12 and 14, respectively is at least one water tube $5. The water tube 536 is sealed into aligned openings and 92 in the tube sheets l8 and 24 respectively. An opening 94 is formed in the tube sheet 36 and an opening 96 is formed in the tube sheet 22. Both of the latter openings are near the bottoms of the respective headers. The opening 94 is shown closed by a sealing plug 93. However the plug 93 is adapted to be replaced by a plumbing connection to a source or" feedwater under sufficient pressure. The plug H92 in the opening 96 is adapted to be replaced by suitable plumbing to a water level indicator tube not shown, and to a length of downwardly extending stub piping suitably sealed oil by a valve, likewise not shown. The latter is for the purpose of effecting a blowdown to remove sediment.

If only one water tube as is used, it is located toward one transverse extremity of the boiler. The opening 96 in which is adapted to be the plumbing for effecting a blowdown, is located toward the opposite transverse extremity of the boiler. By means of this arrangement, sediment that collects in the lower end of each header is easily cleaned out by the blowdown, i. e., letting some of the hot water under pressure in the boiler escape through opening 9.

Due to the presence of the water tube(s) 86, there are no stagnant water pockets in the lower ends $2 and of the headers. Because the water. circulates continuously through all parts of the boiler, there is a minimum of corrosion.

The open sides of the boiler between the headers are adapted to be covered by removable closures, not shown, in a manner similar to that described in connection with closures '72 and 74 except that the side closures are mounted flush with the recessed portions directed in .rdly to reduce size. The latter recesses in the she closures not shown for receiving insulatmg material such as soft brick. Whenever necessary. the outer surfaces of the water tubes 36 may be brushed free of accumulated deposits by simply removing the side closures.

The enti e boiler is arranged to sit on a firebox 1 M. ti with firebrick 112. By not securing the firebox in posir -n on the supporting floor and by not securing it to th boiler it, with any more than a sealing compound tor preventing leak of hot gases from the firebox, it is a simple matter to erect repairs on the fireit is only necessary to chip away the sealing box. compound, jack up the boiler just a bit so as not to put any undue strain on the connecting plumbing and then simply sliding out the firebox. After the repairs are made, the procedure is reversed. Since no grate is shown, the firebox is for fluid fuels. However, the es to a firebox for coal.

in operation, the boiler may be completely filled with water which case it would be a source of hot water or it would be in closed hot water heating system. if the water level below that of the tubes 66, the boiler serves to generate steam. The hot gases originate in the combustion chamber of the firebox Lil). The hot gases rise up, as shown in Pig. 2, around the outer surfaces of the sta gered water tubes and along the inner surfaces of the tube plates 18 and 24, to heat the water on the other side of the surfaces. Be-

cause of the staggered arrangement of the boiler tubes, the gases circulate around all parts of the surfaces of the water tubes 35. The gases rise to the top of the space including the water tube" 36, heating the inner surface of he crown sheet and flow out into the chamber defined by the closure 7 by passing through the bridging pipe The hot gases distribute through the chamber defined by the closure and then divide to flow through fire tubes to heat the water between the fire tubes 38 and the water tubes 36. Upon leaving the fire tubes 3% at the left side of the boiler as seen in Fig. 2, the gases again combine as a body in the chamber defined by the closure "F2 and rise upwardly dividing among the several fire tubes 66 to flow into the bridging or smoke box 76 on the way to the smoke pipe as and then to the chimney not shown. Assuming that the headers 12 and 14 are completely filled with water, the level of the water terminating just below the lower surfaces of the fire tubes 66, the boiler produces steam eificiently and rapidly. The efiicient and rapid generation of steam is due to the fact that the hot gases of combustion make three passes through the water. The first "pass of the hot gases is the latters rising upward from the combustion chamber in the firebox lit toward the crown sheet 32. The second pass of the hot gases is the latters flow through the fire tubes 33. The third pass is the latters flow through the fire tubes as toward the smoke pipe 63. Aside from the passes additional heat transfer occurs as the hot gases move along the surfaces of the tube sheets 16, i3, .22 and A plug liif. is shown scaling the opening Actuall it is preferable to connect a pipe of suitable length one of its ends so that it is sealed within the opening 95. The other end of which pipe may be selectively opened or closed by means of a gate valve. The valved end of the above-mentioned pipe would preferably feed into Ell.

the sewage system. By this arrangement of pipe and valve, not shown, sediment that collects in the bottom of the headers 12 and 14 also called water legs 82 and 84 may be expeditiously disposed of with a minimum of effort and without curtailing operation of the boiler. By simply opening the valve in the pipe connected to the opening or openings 96 a blowdown is efiected removing all of the sediment collected in the water legs 86 and 88.

The eifects of additional passes for increased heat transfer plus tilted tubes 38 and connecting tube 86 for increased water circulation combine to make the disclosed boiler compact for its rating, efiicient, and less subject to breakdown resulting from corrosion. The arrangement of the closures as discussed previously simplify cleaning and repair.

Obviously many modifications and variations of the present invention are possible in the light of the above teachings. It is therefore to be understood that within the scope of the appended claim the invention may be practiced otherwise than as specifically described.

I claim:

A boiler comprising a pair of parallel horizontallyspaced vertical headers, each of said headers including an inner tube sheet, an outer tube sheet, a first arched crown sheet joining the upper extremities of the inner tube sheets; a second arched crown sheet joining the upper extremities of the outer tube sheets, whereby a domed space is defined between said crown sheets; the tube sheets of said headers being formed with a plurality of vertically staggered sets of aligned openings, each set of aligned openings including one opening in each of the tube sheets and each set of openings being at a predetermined angle relative to a plane defined by the bases of said headers; a plurality of pairs of concentric around the water tubes, said inner tube sheets further formed with a pair of aligned openings adjacent the lower extremities thereof; a water tube secured within the last mentioned pair of openings in the inner tube sheets for eliminating stagnant water pockets in the lower extremities of said headers; the upper extremities of the tube sheets of one of said headers formed with a pair of aligned openings for receiving a bridge pipe; a bridge pipe sealed into the aligned openings formed in the upper extremities of the tube sheets of the said one header; the outer tube sheets further formed with a plurality of axially aligned openings above the level of said crown sheet; a plurality of horizontal fire tubes sealed in the last mentioned aligned openings formed in the outer tube sheets; a removable recessed closure secured to the outer tube sheet of each of said headers for defining a chamber with one of said headers common to one end of each of said fire tubes and one end of said bridge pipe and for defining a chamber with the other of said headers common to the other end of each of said fire tubes and one end of said plurality of horizontal fire tubes said boiler adapted to be supported on a fire box whereby hot combustion gases originating in the firebox are adapted to rise circuitously about the water tubes, flow through said bridge pipe into the chamber defined by one of said removable recessed closures and thence through the fire tubes into the chamber defined by the other removable recessed closure, through said fire tubes located above said first crown sheet toward a chimney for raising the temperature of fluid adapted to be disposed in said headers, in the spaces between the inner and outer tubes of the concentric pairs, and above said first crown sheet.

References Cited in the file of this patent UNITED STATES PATENTS 228,978 Brown June 22, 1880 661,868 Hallett et a1. Nov. 13, 1900 889,388 Moran June 2, 1908 2,008,918 McKee July 23, 1935

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