Gas Burner

Abstract

A gas burner formed as a hollow elongate tube having an entrance and a closed end, the tube having an upper wall and a plurality of spaced openings formed along a length of said upper wall, an inwardly depending baffle portion adjacent each opening, each baffle portion having a length substantially equal to one dimension of the adjacent opening.

Description

FIELD OF THE INVENTION

This invention relates to sheet metal gas burners and more particularly provides a gas burner having gas flow stabilization means which provide improved burning characteristics of the gas at the ports of the burners.

BACKGROUND OF THE INVENTION

Elongate sheet metal gas burners are known in the prior art and are normally provided with a mixing chamber into which there is injected a quantity of gaseous fuel from a gas orifice, the gaseous fuel leaving the orifice at high velocity, forming a jet and entraining therewith a quantity of so-called primary air. Thus, a mixture of gaseous fuel and primary air is created and then moves interior of the burner. The burner is provided with a plurality of burner ports from where the gas and primary air is discharged. The aforesaid mixture is ignited initially as it is discharged from the burner ports and thereafter continues to combust at the ports until the gas supply is shut off.

Prior art burners have been formed of sheet metal, have been lightweight and generally of compact size. However, problems are encountered in achieving flame stability at the burner ports so as to avoid flashback, flameout, unequal flame characteristics along the length of the burner and incomplete combustion. It has been known to vary the cross sectional dimension of the burner interior along the length of the burner in an attempt to provide combustion uniformity along the length of the burner. It is also known to provide, effectively, a continuous port with uniform bridges along the length thereof in an effort to obtain increased flame stability.

Efforts also have been made in attempts to reduce the cost of gas burner constructions in the manufacturing stage by various different manners of providing the ports therein. Often unusually accurate and precise location and variation of the port areas have been critical to its manufacture. It is desirable to construct gas burners in a manner that takes advantage of possible savings during the manufacturing stage such as scrap loss reduction, the precision required, and alike.

It should be noted that when the gaseous fuel, primary air mixture is discharged from a burner port, the principal velocity component thereof acts on a path in a direction transverse to the direction of movement of the mixture in the interior of the burner and therefore another velocity component is created to act on the gaseous fuel-primary air mixture being discharged. It is this additional second velocity component which causes the flames to lift and in some cases to flashback or to provide yellow tips, an indication of incomplete combustion. It would be desirable to attempt to eliminate this second component of velocity and thus remove a principal cause of flame lift, flameout, flashback or yellow tip, that is, incomplete combustion.

SUMMARY OF THE INVENTION

A gas burner comprising a hollow elongate tubular member having an upper horizontal wall and a plurality of outlet ports formed in said wall along the length thereof and spaced ones from the others. Baffle means are formed integral with the upper horizontal wall and depending from said wall interior of said burner adjacent each outlet port, preferably arranged at an acute angle (not greater than 90.degree.) relative to said horizontal wall. The cross section of the hollow gas burner is uniform along its length and the baffle means comprise tabs integral with said burner and extending interior thereof.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is a perspective view of one embodiment of a gas burner in accordance with the present invention.

FIG. 2 is a front cross sectional view of the gas burner of FIG. 1 taken along lines 2--2 of FIG. 1.

FIG. 3 is a fragmentary side sectional view of the gas burner of FIG. 1 taken along lines 3--3 of FIG. 1 and in the direction indicated.

FIG. 4 is a fragmentary plan view of the gas burner according to the invention.

FIG. 5 is a fragmentary diagrammatic view of the gas burner according to the invention shown in the process of manufacture.

FIG. 6 is a fragmentary plan view of a modified embodiment of the invention.

FIG. 6A is a fragmentary perspective view of another modified embodiment of the invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Referring to the drawings, there is illustrated in FIG. 1 a gas burner device 10 constructed in accordance with the invention. The gas burner 10 is formed of thin sheet metal bent into a hollow, generally rectangular configuration joined together by brazing, staking or welding as shown at 12 to form the elongate body 14. The body 14 is closed at one end 16 and open at the opposite end 18 to define an entrance 20. A plurality of ports 22 are formed in the upper horizontal wall 24 of the body. The interior portion of the body 14 adjacent the entrance 20 defines a mixing chamber 26 while the portion of the body 14 along the ports 22 is designated as the burner head chamber 28, both mixing chamber 26 and head chamber 28 being in communication with each other and with the atmosphere through the open end 18 of the body 14. Each of the burner ports 22 are of generally rectangular shape, the longer portion being transverse the top wall 24. Inwardly directed tabs 30 are formed bordering one edge 32 of the longer edges of the burner port 22, said one edge 32 being closer to the open end 18 of the body 14 than the other edge of said port. Each port 22 has a tab 30 extending from the top wall 24 interior of the body 14 at an angle, preferably 90.degree. or less.

The tabs 30 act as a baffle to destroy the velocity component of the gas-primary air mixture at the ports 22 so as to obtain increased flame stability.

In operation, gaseous fuel under pressure is supplied through a nozzle or gas orifice 33 and injected into the mixer chamber 26 where the gas jet thus develops and entrains a quantity of primary air which enters the mixing chamber 26 through the open end 18. While the quantity of gaseous fuel is comparatively small and enters at a very high velocity, the quantity of air entering is comparatively large and enters at a relatively low velocity. As the gaseous fuel-primary air mixture is formed, the mixture velocity causes the mixture to move from the mixer chamber 26 into the burner head chamber 28 from where the gas-primary air mixture is discharged through the burner ports 22 into a combustion chamber (not shown) of a heating device (not shown). As the gaseous fuel-primary air mixture leaves the burner port 22, it is initially ignited by a pilot burner (not shown) and then continually combusts utilizing secondary air to complete the combustion process.

The characteristics of flame stability of gas flames at burner ports 22 are conventionally classified as flashback, lifting and yellow tip limits. In the burner illustrated herein, the main velocity component of the gaseous fuel-primary air mixture on discharge thereof from the burner port 22 acts on a path in a direction transverse to the direction of movement of the gas-air mixture within the mixing chamber 26 and the burner head chamber 28, thereby permitting another velocity component, a secondary velocity component, to act on the gas-primary air mixture in its discharge from the burner port 22. It is the effect of this second velocity component which causes the flame to lift and in some cases, to flashback or to incompletely combust and hence have yellow tips. Due to the baffling effect of the tabs 30 disposed in the path of the gas-primary air mixture as the mixture moves through the burner head chamber 28, the flow of the mixture is impinged or impeded. This effect does not significantly reduce the flow velocity of the main body of gas-primary air mixture and thus there is no problem with respect to the maintenance of the uniform pressure along the length of the body 14. The localized impinging of the gas-air mixture causes local turbulence in the region immediately adjacent to the burner ports 22 and thus eliminates the additional or secondary velocity component from the gas-primary air mixture as it is discharged from the burner port 22.

Of course, the relative size as well as the spacing of the burner ports 22 may be varied to achieve different pressure distributions within the body as desired. Preferably, the ports 22 are spaced so that they are close enough to allow cross-ignition from one port to the other along the entire burner head chamber but are spaced far enough to avoid coalescing of the flames at the ports. Also, the configuration of the tabs 30 may be other than rectangular depending upon the manufacturing process.

Spaced longitudinal slits 34 and cross slits 36 are formed in a series along that portion of the sheet metal blank which will define the top wall 24. These slits 34, 36 are arranged so as to define a substantially U-shaped cut. Subsequent to the formation of the body 14 and welding together of the same as shown at 12, the portion or tabs will be bent along the fold line 38 inwardly toward the burner head chamber 28 so that the burner ports 22 are defined each by the edges of slits 34 and 36 and the exterior surface of the tab 30. The use of semi-circular cuts as shown in FIG. 6 in lieu of the U-shaped cut is contemplated so that there are resulting semi-circular ports 22' and semi-circular tabs 30'. Note that the ports 22' in FIG. 6 are of unequal size, here being arranged in order of progressively increasing size. Uniformity in port size is preferred for economic reasons with the spacings adjusted so the larger spacings occur near the entrance side or open end of the burner. In FIG. 6A, the ports 22" are defined by substantially circular, punched openings, with an integral link joining the remainder of the wall to the resulting, almost circular tab 30". The tabs may be modified to assume a different shape relative to the port configuration.

Claims

What we claim is:

1. A gas burner comprising a hollow elongate member of uniform cross-section along its length, a closed end and an open end defining an entrance, said body member having an upper horizontal wall, a plurality of spaced outlet ports formed in said wall along the length thereof and baffle means integral with said upper horizontal wall and extending from said wall interior of said body adjacent each outlet port, said baffle means comprising depending tabs of substantially U-shaped configuration directed angularly toward the interior of said body, said tabs being integral with said wall along that edge of each outlet port which is closest to the entrance.

2. The gas burner as claimed in claim 1 in which a portion of said upper horizontal wall is imperforate.

3. The gas burner as claimed in claim 1 in which said plurality of outlet ports are formed in said horizontal wall beginning from a location spaced from said entrance.

4. The gas burner as claimed in claim 3 in which said plural outlet ports extend along said wall to a location adjacent said closed end.

5. The gas burner as claimed in claim 1 in which the tabs and the outlet ports are of substantially identical size and configuration.

6. The gas burner as claimed in claim 1 in which said tabs are directed interior of said body from said wall at an angle substantially 90.degree. relative thereto.

7. The gas burner as claimed in claim 3 wherein the interior of said body is defined as having a mixing chamber adjacent the entrance, and a burner head chamber coextensive with said plurality of outlet ports, said horizontal wall being imperforate coextensive with said mixing chamber.

8. The gas burner as claimed in claim 1 wherein said outlet ports are arranged spaced unevenly along said wall.

9. The gas burner as claimed in claim 1 wherein said outlet ports are spaced apart a distance at least equal to the narrower dimension thereof.

10. The gas burner as claimed in claim 1 wherein said outlet ports progressively increase in size.

11. The gas burner as claimed in claim 1 wherein said baffle means and said outlet ports are of substantially identical configuration.

12. The gas burner as claimed in claim 11 wherein said outlet ports and said baffle means are of arcuate configuration.

13. The gas burner as claimed in claim 11 wherein said outlet ports and said baffle means are of substantially semicircular configuration.

14. The gas burner as claimed in claim 11 wherein said outlet ports and said baffle means are of substantially rectangular configuration.