Power Burner

Abstract

A power gas burner is provided having a perforated plate through which air passes and is mixed with gas introduced into the burner at right angles to the direction of airflow and immediately in front of the plate, to provide a combustible mixture which burns with a short, intense, flame, free from lifting and pulsation. A mantle of gas-free air surrounds the flame to avoid corrosion of parts of the burner. The air for combustion passes through the plate at a high velocity such as to create a partial vacuum at the front of the plate, which is effective to maintain the flame against the plate.

Description

In Misner U.S. Pat. No. 3,330,485, a gas burner is disclosed having a deflector plate against which air flowing through a blast tube impinges, and through perforations of which the major portion of the air delivered by the blast tube passes forwardly through a mixing chamber in a streamline flow confined by a sheath of gas emanating from holes in a retention plate. This air constitutes what is referred to as the "secondary air supply" and remains largely unmixed with the gas for a considerable distance forwardly of the deflector plate.

The deflector plate also forms a sufficient restriction to the flow of air therethrough that it builds up a slight static pressure in the blast tube behind the deflector plate, with the result that a minor proportion of the air, instead of passing through the perforations of the deflector plate with a streamline flow, is deflected laterally outwardly past the edges of the deflector plate, and is thereby caused to impinge against jets of gas emerging from holes in the retention plate and to intermix therewith. This deflected air constitutes what is referred to as the "primary air supply," mixing thereof with the gas occurring during the time the air and gas traverse the axial length of what is termed an extension tube, which forms a mixing chamber.

Although the aforesaid burner design is stated in the patent to cause the flame to burn quietly from the exit face of the extension tube, without pulsating or "popping," we have found that the burner flame does, in fact, pulsate, and does not burn efficiently as stated. The reasons for this may be enumerated as follows:

1. Since the secondary air supply remains, as stated, largely unmixed with the gas for a considerable distance forwardly of the deflector plate, the flame burns at the exit end or face of the extension tube, but the distance or space between such flame and the deflector plate is, in fact, so great that the flame is a substantially long flame, which completely fills this space. With a flame of such length, considerable pulsating occurs, and moreover, this flame also causes combustion of the mixture of primary air and gas, causing the extension tube to become excessively heated and to a point at which corrosion of blistering of the tube occur. At the same time, portions of the pilot burner assembly within this space become corroded or otherwise damaged.

2. Since, as stated, the deflector plate forms a restriction to the flow of air therethrough to an extent such that a slight static pressure in the blast tube behind the deflector plate is built up, it follows that only a slight vacuum is produced by the air flowing through the deflector plate, which vacuum is insufficient to hold the fire or flame tightly against the forward face of the deflector plate, and thereby avoid pulsation of the flame.

3. The gas, in the Misner patent, flows in a direction parallel with the direction of airflow, so that complete and thorough mixing of the gas and air, and particularly of the gas with the secondary air, is not possible. There is, in fact, a mixing with or aeration of only a small portion of the gas by the primary air, similar to what is normally obtainable by a "venturi" effect.

The present invention has, as its primary object, the provision of a gas burner which overcomes all of the aforesaid disadvantages, and in which the gas and air are mixed as completely as possible before the air from the blast tube passes appreciably beyond the perforated plate, so that combustion is virtually completed before the combustible mixture reaches the end of the extension tube or nozzle of the burner.

Another object of the invention is to provide a burner of the character described, in which a very short flame is maintained against the forward face of the plate, which flame is free from lifting and pulsation.

A further object of the invention is to provide a burner of the character described, in which a mantle of air is maintained between the extension tube or nozzle of the burner and the periphery of the flame, to thereby blanket the inside of the tube or nozzle and avoid corrosion or blistering thereof.

A further object of the invention is to provide a burner of the character described, in which the air which passes through the perforated plate at a high velocity such as to produce a partial vacuum on the plate which holds the gas-air mixture back against the plate, so that thorough mixing takes place inside the surrounding air mantle.

A still further object of the invention is to provide a burner of the character described, in which the gas is introduced into the burner at right angles to the direction of airflow, in controlled amounts, such as to produce a complete and homogeneous combustible mixture of the gas and air adjacent the plate.

Other objects and advantages of our invention will be apparent during the course of the following description.

In the accompanying drawing, forming a part of this specification, and in which like numerals are employed to designate like parts throughout the same,

FIG. 1 is a longitudinal cross-sectional view of the power burner, taken on the line 1-1 of FIG. 2, and

FIG. 2 is a transverse cross-sectional view, taken on the line 2-2 of FIG. 1.

Referring more particularly to the drawing, the burner will be seen to comprise a tubular member or hood 1, preferably made of steel, having a conical inturned flange 2 at its forward end, which comprises the nozzle of the burner.

Disposed within the forward portion of the tubular member 1, rearwardly of the junction of the member 1 with its flange 2, is a plate 3, of generally circular configuration, made of stainless steel, which extends diametrically across the tubular member 1, and has peripheral portions thereof removed to provide circumferentially spaced arcuate openings 4 and 5, which serve a purpose to be presently described.

Removal of these peripheral portions of the plate 3 leaves circumferentially spaced tongues 6 and 7 which may be welded to the inner wall of the member 1 to maintain the plate 3 in position.

The plate 3 is also provided with a multiplicity of spaced holes or openings 8 which serve a purpose to be presently described. The plate is provided below its center or axis with an enlarged opening 9, within which is mounted the forward end of a pilot assembly 10, to which gas is supplied, as by a gas line 11. Noteworthy at this point is the fact that virtually the entire pilot assembly is disposed rearwardly of the plate 3.

The plate 3 is also provided at diametrically opposite points adjacent the top and bottom of the plate with recesses or openings 12 and 13, within which are mounted gas jet nozzles 14 and 15, respectively, which may be welded to the plate. These gas jet nozzles have axes parallel with the axis of the plate 3, and extend from a point spaced rearwardly of the plate 3 to a point spaced forwardly of the plate but at a relatively short distance from the plate, as compared with the entire distance from the plate to the forward edge of the flange 2. The nozzles 14 and 15 are closed at the front and open at the rear.

The nozzle 14 is provided in its side wall with axially aligned orifices 16 and 17 and in its bottom with an orifice 18, the axis of which is perpendicular to the common axis of the orifices 16 and 17.

The nozzle 15 is provided in its side wall with axially aligned orifices 19 and 20.

The axes of the orifices 16, 17, 18, 19 and 20 lie in a common plane parallel to the plane of the plate 3 and disposed in closely spaced relation to the front face of the plate 3 forwardly of the latter.

The nozzles 14 and 15 are coupled to gas supply pipes or lines 21, as by means of couplings 22. The pipes 21 and couplings 22 are coaxial with their respective gas jets.

The operation or use of the burner may be described as follows:

Air under pressure is passed through the tubular member 1, the major portion of this air passing through the holes or openings 8 of the plate 3, and a lesser portion of the air passing through the arcuate openings 4 and 5 to provide a mantle of air which blankets the inner wall of the member 1 and flange 2.

At the same time, the gas introduced into the gas jet nozzles 14 and 15 is blown across the front of the plate 3 through the orifices 16, 17, 18, 19 and 20. This gas mixes with the air which passes through the holes or openings 8 to form a combustible mixture which is ignited by the pilot assembly 10. The air issuing from the holes or openings 8 is moving at a high velocity, producing a partial vacuum on the plate 3, which holds the air and gas back against the plate, so that thorough mixing of the air and gas takes place in a narrow zone immediately forwardly of the plate 3, and inside of the surrounding air mantle or blanket provided by the air issuing from the openings 4 and 5. This produces a short hard fire free of lifting and pulsation.

The burner, as described, is free from all of the disadvantages described with reference to the Misner patent, and is characterized by the fact that the gas and major portion of the air are mixed as completely as possible before the air introduced into the tubular member 1 passes appreciably beyond the plate 3, so that combustion is virtually completed before the combustible mixture reaches the end of the member 1.

The flame is a very short and intense flame, which is maintained against the forward or front face of the plate 3, so that it is virtually free from lifting and pulsation, burning very quietly.

A mantle or blanket of air, substantially free of gas, is maintained between the inner wall of the member 1 and the periphery of the flame, to thereby insulate the flame from the member 1 and avoid corrosion or blistering thereof.

The gas is introduced into the burner at right angles to the direction of the airflow, in controlled amounts such as to produce a complete and homogeneous combustible mixture of the gas and air adjacent the front face of the plate.

The pilot assembly and associated parts, being disposed rearwardly of the plate 3 are shielded or guarded against oxidation or corrosion produced by the burner flame, and the vacuum or partial vacuum produced by the combustion air is effective to prevent ingress of the burner flame into the pilot assembly, thereby protecting the pilot assembly from the effects of the flame.

It is to be understood that the form of our invention, herewith shown and described, is to be taken as a preferred example of the same, and that various changes may be made in the shape, size and arrangement of parts thereof, without departing from the spirit of the invention or the scope of the subjoined claims.

Claims

We claim:

1. In a burner of the character described, a tubular member for passage of air under pressure, a plate extending diametrically across said tubular member at a point spaced rearwardly from the forward end of said member, said plate having spaced perforations for the passage of air therethrough, means for introducing gas through said plate at points adjacent the periphery of said plate, and means for directing said gas into said air in a direction substantially perpendicular to the direction of airflow and in a plane closely adjacent and parallel to the forward face of said plate, to provide a combustible mixture which produces a short flame, substantially free of pulsation, said last-named means including tubular gas jet nozzles extending through said plate and having orifices in the said sidewalls thereof, said plate having peripheral portions thereof removed to provide arcuate openings or passageways adjacent the inner wall of said tubular member, so that a portion of the air passing through said tubular member passes through said passageways to provide a blanket or mantle of air which encompasses the periphery of said flame and is effective to prevent oxidation or corrosion of said tubular member.

2. A burner, as defined in claim 1, wherein said gas jet nozzles are closed at their forward ends.

3. A burner, as defined in claim 2, wherein said tubular member is provided at its forward end with an inwardly directed conical flange, which is effective to cause said blanketing air to be directed inwardly adjacent the forward end of said member.

4. In a burner of the character described, a tubular member for passage of air under pressure, a plate extending diametrically across said tubular member at a point spaced rearwardly from the forward end of said member, said plate having perforations for the passage of air therethrough, means for introducing a fuel gas through said plate, said means comprising at least two spaced conduits disposed closely adjacent the inner wall of said tubular member and having their axes substantially parallel with the axis of said tubular member, said conduits being diametrically opposed and at the outer periphery of said plate and having at least a pair of oppositely directed ports in the walls thereof forwardly of said plate for directing said fuel gas from said conduits and into said air in a direction substantially perpendicular to the direction of airflow, and generally away from direct impingement against the inner wall of the tubular member in the vicinity of said conduits and in a plane closely adjacent and parallel to the forward face of said plate, to provide a combustible mixture which produces a short flame across the face of said plate and substantially free of pulsation.

5. The method of operating a burner comprising a tubular member, a plate extending diametrically across said tubular member at a point spaced rearwardly from the forward end of said member and having perforations therein, and at least two spaced conduits extending through said plate and disposed closely adjacent the inner wall of said tubular member and having their axes substantially parallel with the axis of said tubular member, and having ports in the wall thereof forwardly of said plate, said method comprising the steps of directing air through said plate from behind said plate and through said perforation, further directing a fuel gas through said conduits and out of said ports in at least two diametrically spaced points and into said air in a direction substantially perpendicular to the direction of airflow and in a plane closely adjacent and parallel to the forward face of said plate and generally away from the periphery of said plate in the vicinity of said conduits, whereby to provide a combustible mixture which produces a short flame.

6. In a burner of the character described, a tubular member for passage of air under pressure, a plate extending diametrically across said tubular member at a point spaced rearwardly from the forward end of said member, said plate having spaced perforations for the passage of air therethrough, means adjacent the periphery of said plate for introducing gas through said plate and for directing said gas into said air in a direction substantially perpendicular to the direction of the airflow and in a plane closely adjacent and parallel to the forward face of said plate, to provide a combustible mixture which produces a short flame, substantially free of pulsation, said burner having elongated passageways or openings between the periphery of said plate and the inner wall of said tubular member, for the passage of a portion of the air passing through said tubular member to provide a blanket or mantle of air which encompasses the periphery of said flame and is effective to prevent oxidation or corrosion of said tubular member.

7. The method of operating a burner as defined in claim 5 including the further step of passing a portion of the air adjacent the inner wall of said tubular member in the form of a blanket or mantle of air which encompasses the periphery of the flame to prevent oxidation and corrosion of said tubular member.