US2587849A - Horizontal fire tube welded boiler - Google Patents

Description

March 4, 1952 H. L. HOSKING HORIZONTAL FIRE TUBEY WELDED BOILER 4 Sheets-Sheet 1- Filed Oct. 16, 1946 f/awgr L v my INVENTQR f/asi March 4, 1952 H. L. HOSKING HORIZONTAL FIRE TUBE WELDED BOILER 4 Shets-Sheet 2 Filed 001;. 16, 1946 INVENTOR #02 15 L. fiasizrzy WTTORfiL-IY March 4, 1952 H. L. HOSKING 2,587,849

HORIZONTAL FIRE TUBE WELDED BOILER Filed on. 16, 1946 4 Sheets-Sheet s INVENTOR WZM Patented Mar. 4, 1952 UNITED STATES PATENT EFFICE HORIZONTAL-FIRE TUBE BGILER Homer L. Hosking, Scarsdale, N. Y,,;assignor to Republic Boiler CorpcratiomNew York, N. Y.

Application October 16, 1946;Seria'l No. 703;6'05

4 Claims. l

This invention relates to furnaces in general *andin particular to furnaces or heaters of the low pressure type intended for household or industrial use.

Household and industrial type low pressure boilers have been generally made of castmetal but with recent improvements in oil hiring and mechanical stokers such types of boiler becomes ineflicient. The trend accordingly is toward boilers made up of plate metalwelded together into a unitary structure thereby increasing the effrciency of the boiler'anddecreasing the-possibility .of poisonous :gases escaping :into the home or business establishment. The bulk of welded boilas now being made make use of circular fire tubes. In other words, they are more or less :copies of the fire tube high pressure type of that the metalimmediatelyunder the bubble is raised to ahigh temperature. Theresult is-that before too long a period. small holes are eaten through the top of the tube and the boiler springs (a leak which :with welded construction "necessirtates either .completetscrapping: of the unit- 01 its return .to l a factory *or competent repair plant.

:Forthemostsrapid rate of heat transmission from the ;hot gases :to the fluid, the gases shou'ld have .a turbulent tmotioniand the fluid a smooth streamlinermotion without turbulence. Furthermore, 'therrate of heat transmissionis dependent may be fairly high on the bottom surface but :during heating of Water the volume of the-heated particles increases and if this :increase: or expansion takes place without pressure changes, that is at a constant depth of water, then-the entire expansive force is directed horizon-tally. 7

From this it can be seen that the instantaneous forces:acting on .aipar-ticleoi water when heated can be considered as a vertical force .due to-density change andta horizontal force due to volume cchange. By calculation fromestablished physi- :cal tables .it will be found thatthe instantaneous resultant of these forces will vary from .26 degrees :33 minutes to the horizontal at .10 degrees .centigrade to 23 degrees and ld'minutes at 1.10

degrees .centigrade. If the angle of the resultant is calculated for-eachtendegrees increase from .lOdegrees to 1.10 degreesoentigrade and answerage taken it will be found to be approximately :25 degrees 13minutes. If now a heatedmlate be placedtapproximately at this angle themaximum heating efficiency should be obtained with the heatedparticlesrising under a constant --vertical acceleration force and being .replacedby-cooler particles also moving under .a constant horizontal. acceleration force. In other words, the particles will be constrained to move approximately themetal surface'andcorrode the same. That" thisscrubbing action is quite strong can betseen .irom the fact that the cosine of 25 .degreesis slightly greater than twice thesine of 25 degrees. In other words, the horizontal-component-of the .force causing the flow between the a plates will be roughly twice the vertical component;

But,..since a flue must have depth to permit passage of the .hot gases, the hot plate will take .on a rectangularshape with its width inclined at roughly 25 degrees to :the horizontal. This rectangular flue will :necessarily v ive a greater .metallic'areaincontact w-iththe water than-will an equal length round tube or .=flue for atgiven (volume of hot gas-flow through the tube .or-Lflue'. .The rectangular flue will also give :a .more tur bulent flow of hot gas which coupled with the greater areawill allow more heat to :be extracted from the hot gases" within agive'nfurnace'diniension.

Itis an objectgtherefore,:of'the presentinven- \tion to provide a heating-boiler having-rectangula'r flues positioned so that allwsurf'aces "make an angle withlrespect to a horizontal plane.

Another object of i the invention i the-provision of: a heating" boiler "having-fire fines or rectangular 1 vision of a heating boiler having rectangular fiues in which may be inserted removable baflle member to cause turbulent flow of gases in the fiues while at the same time serving as soot removers.

These and other objects of the invention will be apparent to persons skilled in the art from a study of the following description and accompanying drawings, in which 7 Fig. 1 is a front view of the heating boiler with parts broken away to better disclose'the construction;

Fig. 2 is a sectional view taken substantially on line 22 of Fig. 1;

r Fig. 3 is a rear view of the boiler, and

Fig. 4 is a sectional view similar to Fig. 2 but showing a modified form of greater heating capacity. 7

Referring now to the drawings in detail it will be seen that the rough boiler will be enclosed in a casing C as indicated by line and dash in Figs.

1, 2 and 3. The boiler itself is made up of welded metal plates secured together to form a unitary structure, although in some cases it may be desirable to form the boiler in parts to be bolted together or otherwise attached to form the com- 1 plete unit. As shown the boiler shell is made up of a single piece of metal having its central portion curved as at 2 with the ends directed vertically downward to form the sides 4 of the boiler and with the terminal edges flanged inwardly as at 5 to provide the boiler support or anchoring surfaces. The shell is completed by welding a front plate 6 and a rear plate 8 to the shell wrapper sheet forming the sides and curved top. The front end sheet 6 has formed therein an inspection opening I0 enclosed by ajswinging-fiap I2 and is also provided with tapped holes for attachment of the water gauge l4. An opening I6 is also cut in the end plate for reception of a heat exchangeunit, not shown, which unit may be installed by removing plate l8 which is shown in Fig. 1- as closing opening It, with the plate held in-positionby bolts or other means 20. sure gauge 22 is shown as tapped into the removable plate I8, although it is, of course, obvious that this gauge may be placed elsewhere on the boiler as can also the water gauge I4 previously referred to. The rear shell plate 8 is provided with tapped openings 24 adapted to be closed by washout plugs 26 and is also provided with a larger tapped opening 28 adapted to be closed by plug 30. Removal of either plugs 2601 30 will provide attachments for the return water line or condensate line of the heating. system. As shown the rearend plate of the boiler .does not extend completely to the floor line, but is stopped short of the floor with the space between its lower edge and floor being closed by a removable plate 32. This removable plate a shown has attached thereto a fire pot or box 34. This box may be either permanently built and attached to plate 32 or may be built into the furnace independently of plate 32 at the time of installing the furnace. Plate 32 can be provided with openings to receive the desired type pf oil firing equipment or stoker, but since the position of these openings vary, they have not The presing upwardly between the banks.

been shown but can be inserted by the plumber or by the factory at the time of ordering the boiler. A square box like structure or smoke box 36 is welded to the rear surface of the end plate 8 and has an opening formed in the upper surface for attachment of the smoke pipe collar 38. The smoke box is provided with a cleanout opening 40 closed by an insulated door 42 held in position by hinges 44 and latch structure 46.

The rear end wall 8 has the portion located within the smoke box punched or cut to provide openings for reception of the fire fiues 50. These fire fiues are of rectangular form and made of two pieces of plate, one 52 being of generally U shaped formation and theother 54 being flat and inserted within the upturned edges of the other and welded thereto to form the rectangular fiues of smooth contour. As shown these flues have their ends extending slightly through the rear end wall in the smoke box area and welded thereto as at 56 exteriorly of the plate. The front ends of the fire fiues extend forwardly through the inner flue sheet 60 to which they are welded exteriorly thereof as at 62. The front flue sheet is welded to the rearwardly directed flanges 64 of the front water leg member 66 which has its lower edges flanged as at 68 for weld attachment to the front and sideshells of the boiler. The front water leg is effectively braced by stay bolts or rods 10 extending through the water leg and through the boiler shell and securely welded in position. The dome shaped crown sheet 12 is welded to the front flue sheet 60 and has its side edges flanged as at "M for weld attachment to the boiler wrapper sheet 2 and to the flanges 68 of the Water leg member.. The rear edge of the crown sheet is welded to a rear water leg member 16 which has its lower edge flanged as at 18 for weld attachment to the lower portion of the rear end sheet 8. The crown sheet and shell is braced by stays 80, while the shell wrapper sheet and end sheets are effectively braced by stays 32 curely welded in position. As shown the wrapper shell is provided with tapped openings 84 for reception of necessary. equipment such as the piping carrying the hot water or steam to the heating system. A

The rectangular fiues 50 previously referred to are shown as arranged in two banks of three each in Figs. 1 to 3. and are so located that their major transverse axes, which by geometry are the lines through the centers of the short sides and perpendicular thereto, are located at an angle of approximately twenty-five degrees with respect to the horizontal. Further, these axes of the respective banks converge upwardly and inwardly. This inclined placement of the fiues will cause a strong flow of water or other heating fiuid past and around the fiues. The fluid heated by, the crown sheet will rise and be directed inwardly and upwardly by the lower inclined surface of the first flues of each bank. This of itself will establish a strong current flow- This coupled with the strong current induced between the fiues of each bank will give a rapid flow of fluid across all surfaces of the fiues. The cold fluid entering through the back water leg will be distributed throughout the lower portion of the boiler or flow upwardly past the crown sheet and inclined flueways. It is, of course, obvious that these flueways may be inclined at varying angles dependent on furnace design. However, it has been found that for maximum efiiciency they should be arranged at angles of between twenty and thirty degrees and preferably at angles of twenty-five degrees with respect to thehorizontal With sucha placement maximum wiping action of the fluid onthe flue surfaces is obtained', that is, each fluecontributes to the final result of establishin alstrong flow of fluid within the boiler.

Since with the inclined flues there might be some tendency for the hot gases to stratify and crowd to'theupper corners of the flueways, baflle means are provided; As shown these baffle means comprise a single rod 90 having a bent end or handle 92 and with flat plates 94 welded to the straight portion of the rod. These flat plates occupy substantially half the cross-sectional area of the flueway and will cause the hot gases to follow a tortuous path through the flueway since the plates are arranged alternately on opposite sides of the rod 90. As clearly shown in Fig, 2 the rod has two plates attached to the lower surface and one to the upper surface. This placement will give one reversal of the flow of hot gases. By merely pulling out the rod and turning it through 180 degrees, the two lower plates may be placed at the top of the flue and the upper plate placed at the bottom. This will give a double reversal of the flow of hot gases. In this manner the efficiency of the boiler can be changed where required by draft conditions. It will, of course, be obvious that if desired more plates 94 may be welded to the rods. As shown each flueway is provided with a bafliing rod 90, although it is obvious that where desired these bafliing rods may be left out completely, for example if a stronger flow of hot gases is desired through the lower flues than through the upper. During use it will, of course, be obvious that soot and fly ash will collect in the flueways. This is readily removed by merely pulling out the rod 90 with its attached bafiles scraping the flueways and dragging the soot or fly ash into the smoke box. Insertion of the baffiing rods after removal will, of course, place the furnace in its proper operating condition shown.

With the furnace shown in Figs. 1, 2 and 3 the hot gases and flame from the fire box will pass under the crown sheet forwardly into the smoke connection box bounded by the front water leg and front flue sheet, thence rearwardly through the inclined flueways to the smoke box and exhaust stack. In some cases it may be desirable to increase the boiler capacity by causing the gases to pass through a second set of flueways and such an arrangement has been shown in Fig. 4. With this type of boiler the hot gases after passing through the lower banks of flueways into the cleanout box lllll will rise and pass through a second set of flueways I02 into the smoke box I04. With this larger type of furnace the cleanout door is preferably at the front as is also an inspection opening I06 by means of which the condition of the fire may be observed. Since this boiler of Fig. 4. is otherwise substantially identical with Figs. 1 to 3, the same reference numerals have been used wherever possible; it being understood that the flueways of both the upper and lower passes are inclined as discussed in connection with Figs. 1 to 3 inclusive.

While the invention has been described more or less in detail with specific reference to the drawings and certain angles of the flueways, it will be obvious that under certain conditions slight modifications may be necessary and all such modifications and rearrangements are contemplated aszfalli within. the scope of the appended. claims defining my invention.

What is claimed is:

1. A heating boiler comprising, a shell; a crown sheet and flue sheet within. the shell, and a plurality of banks of angularly disposed longitudinally extending flues of. rectangular crossr-section positioned. on. opposite sides of the longitudinal verticalcentral plane of thelboiler and connecting: the shell and flue sheet above the crown sheet, said rectangular flues having their major transverse. axes inclined upwardly and inwardly toward said longitudinal vertical central plane of the boiler, the angle of inclination of the said major flue axes being substantially twenty-five degrees with respect to the horizontal.

2. A heating boiler comprising a shell, a crown sheet and flue sheet within the shell, a plurality of substantially longitudinally extending flues of rectangular cross-section located within the shell above the crown sheet and connected to said shell and flue sheet, the major transverse axes of said flues being inclined inwardly and upwardly toward the vertically extending longitudinal center plane of the boiler at an angle of between twenty and thirty degrees to the horizontal thereby giving substantially maximum heating efficiency, and removable baffle means within said flues causing tortuous flow of hot gases within the flue, said removable bafiie means being unsymmetrical and reversible in said rectangular flues whereby the flow of hot gases through the flues may be changed.

3. A heating boiler comprising, a shell, an upwardly arched longitudinally extending cylindrically curved crown sheet positioned within the shell and having its sides and at least one end connected to the shell, and a pair of substantially longitudinally extending flues of rectangular cross-section located within the shell above the curved crown sheet and having their upper and lower sides spaced from but substantially parallel to planes tangent to the sides of said upwardly curved crown sheet along straight lines substantially equally spaced from and on opposite sides of the longitudinal vertical plane through the center of the crown sheet.

4. A heating boiler comprising a shell, a crown sheet and flue sheet within the shell, a plurality of substantially longitudinally extending flues of rectangular cross-section located within the shell above the crown sheet and connected to said shell and flue sheet, the major transverse axes of said flues being inclined inwardly and upwardly toward the vertically extending longitudinal center plane of the boiler at an angle of between twenty and thirty degrees to the horizontal thereby giving substantially maximum heating efficiency, and removable baflle means within said flues causing tortuous flow of hot gases within the flue, said removable means comprising a rod and rectangular plates welded to the rod alternately,

on opposite sides thereof.

HOMER L. HOSKING.

REFERENCES CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS (Other references on following page) 7 UNITED STATES PATENTS Number Number Name Date Hogan Apr. 15, 1890 2'200'809 Dixon Aug. 30, 1892 Boynton Feb. 21, 1893 5 23311460 Norton July 1'7, 1894 Brenner et a1. July 2, 1912 V Segelken Mar. 18, 1913 NIH??? Birchfield. Oct. 18, 1921 Tait Sept. 18, 192:; 277'247 Niven Apr. 26, 1932 V I Hall Aug. 21, 1934 Name Date Schmitt Apr. 20, 1937 Anderson et a1. Jan. 3, 1939 Riehl May 19,1940 Burkhart Nov. 25, 1947 FOREIGN PATENTS Country Date Switzerland June 29, 1910 Switzerland June 1, 1918 Great Britain Sept. 15, 1927

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