US2675865A - Fluid fuel furnace and antipuffing means therefor - Google Patents

Description

April 0, 1954 c. 1. BETZER FLUID FUEL FURNACE AND ANTIBUFFING MEANS THEREFOR Filed March 24, 1950 2 Shee'ts-Sheet 1 w w w m a w y W/ W F V m w ,7, m v7. W W a 4% W #2. u W] W a v A i M m A a k t 3nventot (75/15522 Gttornegs April 20, 1954 c, L BETZER $675,865

FLUID FUEL FURNACE AND ANTIBUFFING MEANS THEREFOR Filed Maich 24. 1950 2 Sheets-Sheet 2 3nnenfor (Ittornegs Patented Apr. 20, 1954 FLUID FUEL FURNACE AND ANTIPUFFING MEANS THEREFOR Cluyd .L. Betzer, Rochester, N. Y., assignor to General Motors Corporation, Detroit, Mich., a

corporation of Delaware Application March 24, 1950, Serial No. 151,700

(El. l58-i) 9 Claims.

This invention relates generally to furnaces which are adapted for use with fluid fuel burners and particularly to an air supply sleeve construction used in conjunction with a burner tube connecting a firebox and a conventional gun or pressure atomizing type of burner.

When the primary air and oil proportions in a furnace are adjusted to provide a high CO2 combustion content, particularly where there is a long flue travel, a condition known in the art as pufiing often results, wherein the combustion will occur as a series of very rapid puffs. ihe principal object of the invention is to eliminate this pufiing by providing a sleeve of preferably frusto-conical shape which envelopes a portion of a burner tube inside the furnace and which, with the burner tube, defines an annular expansion space providing communication between the firebox and the atmosphere. This feature pro- 'vides an effective method of admitting outside secondary air directly to the firebox through the space between the sleeve and the burner tube for mixing with any unconsumed or partially consumed fuel in the firebox.

A furtherobject of the invention is to provide such a tube and sleeve construction which is simple and inexpensive to manufacture and assemble. Other objects and advantages of the invention will more fully appear from the following description of a preferred embodiment taken in Figure 3 is a fragmentary enlarged sectional view taken substantially on line 33 of Figure 2. Referring more specifically to the drawings, the present invention is shown in Figurev 1 asembodied in a warm air furnace of the gravity air circulation type.

It will be understood, however, that this furnacehas also been designed for and can readily be employed in a forced air circulate.

ing system wherein a conventional blower unit would be mounted below or adjacent thepresent furnace construction, the blower communicating with the bottom of the furnace or with an air in let opening in a lower portion of a side of the furnace. The furnace is shown as provided with an external jacket or casing, indicated generally by 2 it comprising vertical sheet metal panels I i having secured thereto a bottom wall I2 and a top wall It. The top Wall is shown as having an outlet opening it for the warm air to be supplied directly or through suitable ducts to the rooms to be heated. It will be understood that a suitable opening or openings would also be provided in the bottom wall 12 or in a lower portion of a vertical panel for the admission of the air to be heated as it rises or is forced upwardly through the furnace.

The heat transfer unit, which is spaced within the casing It, consists primarily of a combustion shell, indicated generally by [8, and a radiator 2% which are constructed of relatively heavy gauge sheet steel. Although the shape of the combustion shell may vary from that shown herein, it preferably comprises a vertically extending tubular or cylindrical body 22 having a substantially flat bottom wall 2'4 welded to the lower end thereof and a dome-shaped top wall 2% welded to the upper end thereof. These parts of the combustion shell may be readily formed from fiat metal sheets, with the body 22 bent into a cylindrical shape and welded together at overlapping edges and the top wall 26 drawn into the desired shape.

'The radiator 20, shown as being of a type having a preferably annular outer shell, has its upper wall provided with an outlet 28 for the heated air passing upwardly between the dome 2t and radiator 26 to the outlet opening IS in the top wall is of the casing. A combustion gas outlet pipe or flue 36, which is adapted to be connected to the usual stack or smoke pipe, extends outwardly from the radiator through an opening in the casing H3. The diameter of the radiator '26 shown is greater than the diameter of the cor'h- V bustion she'll i8 so that the radiator extends radially beyond the sides of the combustion shell.

Near its lower end the body 22 of the combustion shell is provided with a relatively large opening to receive a burner mounting frame 34, which is welded to the body 22 and extends outwardly to a similar opening in the casing II). This casing opening is closed by a cover or burner mount:- ing plate 38 secured to the shell as by bolts 53,

i best shown in Figure 2, the frame 34'. being similarly aiiixed to the cover or plate 36' by bolts lit through flanges 22. A suitable opening M is provided inthe plate to receive a burner tube it,

preferably constructed of cast iron and which, it

will be noted, doesnot fully occupy this opening. A heavy outwardly extending mounting flange :8 is provided at the outer end of tube 46 and secured to the plate 36 by bolts 58. The burner mounting plate 36 and the flange it, occupying the burner receiving opening in the shell N, form a continuation of and function as portion of the outer casing of the furnace. The oil burner, indice-ted generally at 55, includes a short tube 52 which is shown as having a similar, preferably rectangular flange which is secured to flange &8 by screws Thus, tubes it and 52 form one continuous burner tube or duct from a burner blower E2 to a sheet metal combustion chamber, indicated generally by Ed, in the shell 8.

The oil burner 51% has not been shown in detail, but it will be understood that it is of the gun or pressure atomizing type in which liquid fuel is discharged under pressure through an atomizing nozzle at the end of a pipe 65 in the burner tube 46 and is adapted to mix with air supplied from the blower through the duct lt-52 to form the combustible mixture.

The fuel mixture issuing from he burner nozzle and tube 4% is projected into the combustion chamber or firebox 6c in which practically complete combustion occurs before the combustion gases escape into the combustion shell l8. This firebox 64 is made of relatively thin sheet metal of such material as certain chrome sheel alloys which have been found to withstand the high temperature encountered and attain a maximum temperature and become incandescent almost immediately upon starting the burner, thereby transmitting radiant heat directly to the Walls of the combustion shell l8. From these walls the heat is efficiently absorbed by the air being circulated over the shell.

The firebox 64 may be readily constructed with generally rounded front and rear end portions 66 and G8, which are welded to an intermediate, substantially cylindrical portion iii. The front end portion 68 is formed with a central opening 12 to receive the inner end of the burner tube 16, and the rear end portion E6 is completely closed. An opening in the upper wall of the central portion it provides for the escape of the combustion gases into the combustion shell l8.

Located within the burner mounting frame 34 and forming a jacket around the burner tube 45 is an air supply sleeve M, which is preferably of a frusto-conical shape, thereby forming an annular passage iii between the tube 45 and the sleeve M. This sleeve has its inner end fitted around the coaxial flange l8 projecting from the end portion 58 of the firebox st. The outer edge of this sleeve abuts the inner surface of the burner mounting plate 35, which is preferably provided with metal clips 88 secured to its inner surface. These clips engage the u-shaped securing members 82 which are welded to the external surface of sleeve l4 near its outer edge, the members 82 being positioned within the clips 80 by rotation of the cone. A metal strap 3:3 extends along the inner surface of sleeve "E i and is shown as having one end welded to a lower portion of flange 18. The other end of the strap may be fitted into a notch at the outer edge of sleeve 74 and bent over this edge to hold the firebox 64 in position, the rear end portion of the firebox being mounted on support 85.

The burner tube mounting flange 48 has the lower portion of its inner face recessed to provide air inlet passages or ducts 86 and 8B, which permit communication between the opening 44 in the burner mounting late and the atmosphere. Although the opening A l in the burner mounting plate is shown as generally rectangular in shape,

it will be understood that it may be of any suitable size and shape so long as it is formed to provide communication between the annular passage I6 and the air inlets 35 and 38 in the fiance 8.

The body 22 of the combustion shell. it is provided above the burner receiving opening 11 another, smaller opening to receive the inn of a sleeve or frame 99, which is welded to body 22 and extends outwardly through an. 0 ing in the casing l0 secured thereto. The fmounts an observation door which erably hinged to the frame and adapted o swung outwardly when it is desired to obser e Cl inspect the operation of the burner A wrap around wipe sheet es, having .4 openings for the outlet flue 3e, burner hou 7 '1 sleeve 36 and the frame E l, is provid d the heat transfer unit and the external or casing Hi. This wipe sheet absorbs radiant heat from the combustion shell and radiator 28, this heat being picked up by the air stream rising within the duct Qt? between the wipe sheet and the combustion shell. The space 98 defined by the casing and the wipe tions as an insulating layer to assu 4 cient air circulation and minimize heat loss.

With the above described furnace con tion it will be seen that outside secondary air is drawn into ducts 36 and 38 by the pressure differential created by the burner operation. This air flows through the opening it in the burner mounting plate 35, passes through the annular expansion passage 15 between the burner tube lt and the sleeve 14, and enters the firebox through opening 72. Thus the tendency toward is reduced due to the ability of the annular expansion space 16 to momentarily receive the expanded gases.

During operation of the burner the burner flame and combustion gases rise within the combust n shell 18, and the combustion gases then pass through the radiator 20 to the outlet flue The radiator provides additional heating surfaces for transferring heat to the air which rises or may forced upwardly through the duct in the furnace. Since the radiator extends beyond the side of the combustion shell, it will be seen that the rising air will be diverted by the outer, lower edge of the radiator so that the air will flow between the outer radiator shell and the top wall of the combustion shell I8 and also between the ra diator and the upper portion or" the wipe sheet Various modifications in the arrangement and details of the specific embodiment descril ed and shown herein will be apparent to those skilled in the art and are contemplated as within the scope of the present invention as defined in the claims appended hereto.

I claim:

1. In a furnace having an outer casing, the combination of a firebox within said casing, a fluid fuel burner having a generally cylind burner tube extending through an opening in casing, said tube having its end projecting into proximity to an aperture in a wall of said "firebox, and a substantially frusto-conical sleeve jacketing the burner tube so as to provide an annular space between said sleeve and said tube, said sleeve having its larger end secured to the casing and its smaller end secured to the hr: 0:: wall, said tube provided with an outwardl extending flange secured to the outer surface of the furnace casing, said casing and flange provided with registering passages immediately beneath sensor said tube accommodating communication from the atmosphere through said annular space to the firebox.

2. In a furnace provided with an outer casing with an opening therein, the combination of a firebox within said casing and having an aperture in one wall, a burner mounting plate occupying the casing opening and having its outer edges secured to the furnace casing, said plate provided with a generally central opening, a fluid fuel burner of the pressure atomizi-ng type having a generally cylindrical burner tube extending through but not completely occupying the opening in the mounting plate, said tube having its inner end projecting into but not fully occupying the firebox aperture, and a substantially frustoconical sleeve jacketing the burner tube and defining with it a generally annular axial divergent passage, the larger end of said sleeve being secured to the inner surface of the mounting plate and encompassing the opening therein, the smaller end of said sleeve being secured to the firebox wall and circumscribing the aperture therein, the burner tube provided with an external radially extending flange abutting the exterior surface of said plate and secured thereto, said flange having its inner face provided with a recess registering with a portion of the mounting plate opening to thereby provide for communication of the interior of the firebox through said annular passage with the atmosphere external of said casing.

3. In a furnace provided with an outer casing having an opening therein, the combination of a firebox within said casing and provided with an aperture in one wall, a fluid fuel burner having a burner tube extending through but not completely occupying the opening in the outer casing of the furnace, said tube having its inner end projecting into but not fully occupying the firebox aperture, and an air supply sleeve jacketing the burner tube and defining with it a generally annular passage, said sleeve having one end secured to the inn-er surface of the outer casing of the furpace and encompassing the opening therein and the other end secured to the firebox wall and ciroumscribing the aperture therein, an external radially extending flange on said burner tube secured to the outer casing of the furnace, said flange having a recess therein permitting com-' jecting into but not fully occupying the firebox aperture, and an air supply sleeve having generally conical walls jacketing the burner tube and defining with it an annular axially divergent passage, the larger end of said sleeve being secured to the inner surface of the outer casing and encompassing the opening therein, the smaller end of said sleeve being secured to the firebox wall and circumscribing the aperture therein, said burner tube having an external radially extending flange abutting the exterior surface of the outer casing, the inner faceof said flange being provided with a recess registering with a portion of the opening in the outer casing to permit the interior of the firebox to communicate through said annular passage with the atmosphere external of said casing. a

' 5. In a furnace having an outer casing, 21; firebox within said casing, a fluid fuel burner having a burner tube extending from said casing intoproximity to an opening in said firebox and adapted to project a combustible mixture into said firebox, and a sleeve coaxial with and surrounding said tube in spaced relation thereto so as to define an annular expansion space, said sleeve extending from said firebox to said outer casing, the space between said sleeve and said burner tube communicating with said firebox and with the atmosphere external of said outer casing by means of an opening in the casing wall immediately adjacent to and beneath said burner tube, said outer casing being imperforate above said burner tube in the area defined by the end of said tube.

6. In a furnace having an outer casing, a firebox within said casing and spaced therefrom, a fluid fuel burner including a generally cylindrical burner tube extending from said easing into proximity to an opening in said firebox and adapted to project a combustible mixture into said firebox, and a sleeve surrounding said tube in spaced relation thereto and extending from said firebox to said outer casing with the ends of said sleeve respectively secured to said firebox and said outer casing to form an annular expan sion space, one end of the space between said sleeve and said burner tube communicating with the interior of said firebox through the opening therein and the other end of said space communicating with the atmosphere external of the outer casing only through a small opening in said casing immediately beneath said burner tube.

'7. In a furnace having an opening in a side wall and provided with a fluid fuel burner, the combination of a firebox with an apertured wall within said furnace and spaced therefrom, a generally cylindrical burner tube portion of said burner extending through but not fully occupying the openin in the side wall of the furnace with the end of said tube projecting into but not fully occupying the firebox aperture, and a generally frusto conical sleeve encasing the burner tube and defining an expansion space between said sleeve and said tube, said space thereby being axially divergent toward the side wall of the furnace, the inner and outer ends of the sleeve being respectively secured to the firebox wall and the side wall of the furnace, said aperture in the wall of the firebox providing communication between the firebox and the space defined between the tube and the sleeve, said opening in the side wall of the furnace being fully occupied by said burner tube except immediately adjacent to and beneath the tube, whereby communication is provided between said space and the atmosphere external of the furnace.

8. In a furnace provided with side wall means having an opening therein, the combination of a firebox within said furnace and spatially separated from said side wall means, said firebox having one wall thereof provided with an aperture which is generally aligned with said opening, a fluid fuel burner provided with a generally cylindrical burner tube extending through the opening in the side wall means of the furnace, said tube having its inner'end projecting into the firebox aperture, and a sleeve jacketing the burner tube and having one end secured to said side wall means and radially surrounding the opening therein, said sleeve and said burner tube defining therebetween an annular expansion space, the other end of said sleeve being secured to the firebox and encompassing the aperture therein, said side wall means generally tightly fitting around said tube and providing communication between the atmosphere external of said side wall means and the passage defined by the burner tube and the sleeve only immediately adjacent to and generally beneath said tube.

9. In a furnace having an outer casing, a supplemental chamber constituting a firebox within said casing and spaced therefrom, said chamber having a wall thereof provided with an aperture, a fluid fuel burner external of said outer casing having a generally cylindrical burner tube extending through said outer casing with the end of said burner tube projecting into proximity to the aperture in the wall of said chamber, and a sleeve surrounding said tube in spaced relation thereto and extending from said wall of the chamber to said outer casing to form an annular expansion space, the space defined between said sleeve and said burner tube communicating with the interior of the chamber through the aperture in the wall thereof, said outer casing having wall means generally sealing the adjacent end of said space but providing a small opening in said wall means immediately beneath said tube to provide communication between said space and the atmosphere external of said casing only by means of said small opening.

References Cited in the file of this patent UNITED STATES PATENTS Number Name Date 2,053,003 Koeln Sept. 1, 1936 2,126,417 Sharp Aug. 9, 1 38 2,240,161 Mueller Apr. 29, 1941 2,329,272 Jorolemon Sept. 14, 1943 2,411,181 Altorfer Nov. 19, 1946 2,488,218 McCollum Nov. 15, 1949 2,534,832 Schinman Dec. 19, 1950

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