US2823739A - Gas burner - Google Patents

Description

1953 E. M. MICHALSKI ,823,739

GAS BURNER Filed Aug. 50. 1956 Fig. I.

INVENTOR Edward M. Michnlski AI'TTORNEY GAS BURNER Application August 30, 1956, Serial No. 607,107

3 Claims. (Cl. 158---109) This invention relates to burners and specifically to high capacity gas burners of the type employed in rather large boiler installations and the like.

With such gas burners it is desirable to obtain as. great a range of firing as possible. with high. combustion efficiency being maintained throughout this range together with the attainment of flame stability and with the excess air requirements being kept at a minimum. The present invention is directed toward. the attainment of an improvement in these operating. characteristics of a gas burner.

in accordance with the invention there is providedan air duct or wind box through which combustion supporting air is conveyed with the inlet and outlet of. this duct being disposed so that the air pases through the outlet portion thereof in a direction generally parallel with the axis of the outlet. Positioned within this duct is a gas supply conduit which is axially parallel with the outlet of the duct and which terminates somewhat short of this outlet and has secured to its outer end a cylindrical housing of substantially larger diameter than the conduit and in coaxial relation with the conduit. This housing. is open at the outer end and has a dished annular member interposed between itsinnerand the end of the supply conduitand interconnected with these two members. This housing forms a mixing chamber and the annular member is provided with openings for metering air into this chamber for mixture with the gas flowing therethrough from the supply conduit. At the outer end. of the cylindrical housing there is provided an outwardly flared diffuser cone which is coaxial with the housing and has a central a form an annular air passage therebetween and longitudinally extending ribs are secured to the periphery of the housing and to the diffuser cone to support the latter and retain it in place. Also secured to these. ribs is a guide sleeve which is disposed about the cylindrical housing in coaxial relation with the housing with the axial'dimension of this sleeve being substantially greater than that of the housing and with the sleeves outer end being-spaced from the dilfuser cone to form an annular air passage therebetween. This guide sleeve directs the air through the various openings and passages of the burner so as to provide eflicient combustion of the gas and with this burner organization an extremely wide operating range is obtained with excellent flame stability and extremely low excess air requirements.

It is an object of this invention to provide an improved gas burner organization which, while being simple and economical to construct, is capable of operating over an extremely wide range with minimum excess air requirements and excellent flame stability.

Other and further objects of the invention will become apparent to those skilled in the art as the description proceeds.

Pnited States Patent 2,823,739 Patented Feb. 18, 1958 With the aforementioned'objects in view, the invention comprises an arrangement, construction and combination of the elements of the inventive organization in such a manner as to attain the results desired as hereinafter more particularly set forth in the following detailed description of an illustrative embodiment, said embodiment being shown by the accompanying drawing wherein.

Fig. l is a longitudinal sectional View of the gas burner of the invention showing the gas supply conduit positioned within the air duct or wind box.

Fig. 2 is a sectional view of the burner tip (taken along line 22 of Fig. 3) showing the details of construc, tion thereof at an enlarged scale.

Fig. 3 is an end view of the burner tip taken generally from line 3--3 of Fig. 2.

Referring now to the drawings wherein like reference characters are used throughout to designate like elements the improved gas burner depicted therein includes wind box or air duct lllinto which air is forced from a suitable fan or the like, through inlet 12 with the air passing through the duct and out the outlet portion 14 and with the duct being so constructed that the direction of air flow through this outlet portion 14 is generally parallel with the axis thereof. Positioned within duct 10 is gas supply conduit 16 which extends laterally through the wall of the duct and has its extremity generally in coaxial or axially parallel relation with the outlet portion 14. This supply conduit opens into mixing chamber 18 formed by annular housing 20 which has its outer end open and is secured at its inner end to the tip of conduit 16 by means of dished, annular member 22 which is provided with a number of circumferentially spaced openings 24 to meter the flow of air into chamber 18.

Flame stability is achieved by means of diffuser cone 26 which-is positioned at the. outer endof chamber 18 in coaxial relationwith this chamber and is formed of an outwardly flared annular member having a central opening substantially equal to the diameter of chamber 18. This cone 26 is positioned somewhat forwardly of housing 20 to form. annular passage 28 between the cone and the housing for the admission of air and the cone is held in place by support ribs 30 which extend longitudinally of housing 20 and radially outward from this housing and are secured to the housing and to the cone. Positioned about housing 20 and in coaxial relation therewith is sleeve 32 which is also supported by ribs 30 and which has an axial dimension substantially greater than that of housing 20 in order that it will efiectively act as an air directing member. The outer end of sleeve 32 is positioned rearwardly of diffuser cone 26 so as to form an annular passage 34 between the sleeve and cone for the flow of air around the periphery of the cone at an increased velocity.

In operation gaseous fuel is supplied to conduit 16 and air to duct 10. The fuel from the supply conduit is mixed with air in mixing chamber 18 with the air being metered through openings 24 and with sleeve 32 being eifective to insure the availability of air at these openings as required to accomplish this result. This premixture of fuel and air starts to burn at the outer end of mixing chamber 18 and upon emerging from this chamber is further mixed with air whichpasses through annular passage 28. The air passing over the rear face of diffuser cone 26, through annular passage 34 and over the periphery of the cone creates a low pressure area generally in front of the dilfuser cone so that the mixture of fuel and air from the outer end of chamber 18 is directed outwardly and generally in front of the face of the ditfuser cone and accordingly moves so as to meet the air flowing through passage 34 and about the tensity and is completed a short distance outwardly from this juncture.

With a 1%. inch standard pipe (area of 1.49 sq. in.) for the fuel pipe and 3 inch standard pipe (area of 7.4 sq. in.) for the mixing chamber it has been found that the total free area of openings 24 should be maintained at 7.5 to 10.5 sq. in. in order for proper operation of the burner and that the total free area of annular passage 28 and annular passage 34 should be from 1.5 to and 5 to 30 sq. in., respectively, for satisfactory burner operation, and with these relative proportions excellent burner operation (efliciency, stability and range) is obtained with a gas pressure of from 3.5 p. s. i. g. to zero at the outlet of the burner and an air pressure from Zero to about .433 p. s. i. g. The relative proportions of the burner must be maintained since any appreciable variation from them greatly diminishes the operating properties of the burner, thus the area of the mixing chamber must be about five times that of the gas cenduit, the area of openings 24 must be between five and seven times that of the gas conduit, the area of passage 28 must be between 1 and 3.4 times that of the gas conduit and the area of opening 34 must be between 3.4 and times that of the gas conduit. The length of the chamber 18 must be maintained within 1 and 4 times the diameter of the gas conduit.

The size of diffuser cone 26 is quite critical in that it has been found if the outer diameter of this cone is less than 1.2 times the diameter of chamber 18 unsatisfactory combustion efficiency results and the stability of the burner is destroyed. Thus the outer diameter of the diffuser cone must be at least 1.2 times the diameter of chamber 18 with there being no particular upper limit upon this diameter, the physical dimensions of the location within which the burner is disposed generally being the limiting factor with regard how large the diffuser cone can be.

A burner constructed in accordance with this inven-.

tion and having the aforementioned dimensions has a rating of from a maximum of million B. t. u. heat output per hour to a minimum of Zero and has operated satisfactorily over this wide range. By proportioning the various ports, passageways and chambers as mentioned a stable flame is produced immediately in front of the diffuser cone even though the gas flow is almost zero and the air flow is much greater than that required for maximum burner capacity.

In order for efficient combustion action to be obtained and a stable flame produced it is necessary that the air flowing through the air duct be smooth and not have a turbulent or rotary action as found in many burner designs in order that the various air deflecting and guiding members of the burner tip may function in a manner in which they are intended and designed and a proper mixing of the air and gas be achieved.

While I have illustrated and described a preferred embodiment of my novel organization it is to be understood that such is merely illustrative and not restrictive.

and that variations and modifications may be made therein without departing from the spirit and scope of the invention. I therefore do not wish to be limited to the precise details set forth but desire to avail myself of such changes as fall within the purview of my invention.

What is claimed is:

1. A gas burner comprising in combination a gas supply conduit, a cylindrical housing coaxial with and extending from the outlet extremity of said conduit to form a mixing chamber, said housing having an area about five times.

that of the conduit and a length from one to four times the diameter of the conduit, means interposed between said housing and conduit providing openings having an area between five to seven times the area of said conduit to meter air from the exterior of said conduit into said chamber, an outwardly flared conical diffuser coaxial .with said housing and disposed adjacent the outer end thereof but spaced therefrom sufficiently to form an annular passageway therebetween having an area between 1 and 3.4 times that of the gas conduit, said diffuser being of a diameter at least equal to 1.2 times that of the cylindrical mixing chamber and having an opening therein substantially equal to the diameter of the chamber, a cylindrical sleeve disposed about said housing in spaced coaxial relation therewith with the outer end of said sleeve being axially spaced from the diffuser cone to provide an annular passage therebetween of an area between 3.4 and 20 times that of the gas conduit.

2. In a gas burner the combination of an air duct having an outlet portion through which air passes in a generally axial direction, a gas supply conduit disposed within said duct with its outlet axially parallel with said flow and directed outwardly of the outlet of said duct, a cylindrical housing of enlarged diameter with respect to said conduit and extending outwardly from the outlet of said conduit in coaxial relation therewith to form a mixing chamber, said housing having an area about 5 times that of said conduit and a length from 1 to 4 times the diameter of the conduit, said housing being connected to said conduit with openings being provided in the annulus between the outlet end of the conduit and the housing to meter air from the air duct into said chamber and having an area between 5 and 7 times that of said conduit, an annular outwardly flared diffuser cone positioned at the outer end of said housing in coaxial relation therewith and spaced therefrom sufficiently to form an annular passage having an area between 1 and 3.4 times that of said conduit for admission of air with the outer diameter of said cone being at least 1.2 times the diameter of the chamber, and a sleeve disposed about said housing in coaxial relation therewith with the outer end of the sleeve being spaced from said cone to form an anular passage for air having an area between 3.4 and 20 times that of said gas conduit.

3. In a gas burner the combination of an air duct having an inlet and an outlet arranged so that the air passing through the outlet from the inlet is moving substantially parallel with the axis of said outlet, a gas supply conduit within said duct having its outlet portions axially parallel with the axis of the outlet of said duct and directed outwardly of said outlet, an enlarged cylindrical housing extending from the outlet extremity of said supply duct and forming a mixing Zone or chamber having an area about 5 times that of said conduit and a length from 1 to 4 times the diameter of the conduit, an annular member interposed between said housing and the end of the supply conduit and interconnected therewith, said annular member having openings therein for the admission of air into said chamber, with the area of said openings being between 5 and 7 times the area of said conduit, an outwardly flared annular diffuser coaxial with said housing and extending laterally from the outer end of said housing with an annular passage being provided between the diffuser and the housing, the area of said passage being between 1 and 3.4 times the area of said conduit and the internal diameter of said diffuser substantially corresponding with the diameter of the housing and the outer diameter being at least 1.2 times the diameter of the housing, a plurality of ribs extending longitudinally of and laterally outward from said housing and having said diffuser secured thereto, a sleeve disposed about said housing in coaxial spaced References Cited in the file of this patent .UNITED STATES PATENTS 2,380,463 Poole July 31, 1945

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