US3017920A

US3017920A - Ring burner with flame retention shield

Info

Publication number: US3017920A
Application number: US795716A
Authority: US
Inventors: Eugene T Blockley; Wilbur E Stone
Original assignee: Eclipse Fuel Engineering Co
Current assignee: Eclipse Fuel Engineering Co
Priority date: 1959-02-26
Filing date: 1959-02-26
Publication date: 1962-01-23
Anticipated expiration: 1979-01-23

Description

Jan. 23, 1962 E. T. BLOCKLEY ETAL' 3,

RING BURNER WITH FLAME RETENTION SHIELD Filed Feb. 26. 1959 2 Sheets-Sheet l INVENTORS WILBUR E y Emma T.

Jan. 23, 1962 E. T. BLOCKLEY ETAL 3,017,920

RING BURNER WITH FLAME RETENTION SHIELD Filed Feb. 26. 1959 2 Sheets-Sheet 2 INVENTORS wauauR E. S'rom: BY EUGENE T. BLOCKLEY ATTY.

3,017,920 RING BURNER WITH FLAME RETENTION SHEELD Eugene T. Blochley and Wilbur E. Stone, Chattanooga,

Tenn., assignors to Eclipse Fuel Engineering Co., Rockford, lit, a corporation of Illinois Filed Feb. 26, 1959, Ser. No. 795,716 3 Claims. ((31. 158-7) The present invention relates to burner construction and more particularly to gas burners of the manifold ring type wherein an annular burner ring having a series of circumferentially spaced gas manifold ports therein is positioned in an air stream for discharge of a series of gas jets into the air stream to produce an annular flame.

Heretofore, in connection with gas burners of this general type, considerable difliculty has been encountered in localizing the resultant flame and maintaining the same close to the gas ring so that the same will remain stable at varying gas and air velocities. In the absence of a satisfactory flame-retention or flame-localizing means, there is a tendency for the flame to push away, so to speak, from the gas ring so that ineflicient combustion takes place, or in certain instances, the flame is extinguished due to failure of the gas and air to mix with each other in combustible quantities. This tendency for the flame to shift axially of the gas ring to a region remote therefrom is particularly prevalent when high air velocities are encountered. Various means have been employed in an eifort to localize the flame and among these have been special baffle devices for retarding the flow of air in the eripheral regions of the burner, critical dispositions of the flow angles of the jet-producing gas discharge openings, critical variations in the size and shape of these openings, etc. The principal difficulty associated with such methods resides in the fact that what may be satisfactory for one set of conditions is not satisfactory for another set of conditions. Generally speaking, such methods Will not accommodate wide variations in gas or air velocities.

The present invention is designed to overcome the above-noted limitations that are attendant upon the construction anduse of gas manifold ring burners of the type briefly outlined above, and toward this end, itcontemplates the provision of a novel combination of a gas burner manifold, and a flame retention shield therefor by means of which the resultant flame issuing from the burner manifold may be maintained in close proximity to the latter in a shielded position wherein variations of either gas or air velocity will not displace the flame and wherein, moreover, the flame is at all times generated by a gas and air mixture sufliciently rich to support combustion. The thus shielded flame operates somewhat in the manner of a pilot flame and it is at all times maintained inan out-of-the-way position wherein it is not affected by turbulence in the combustion chamber and wherein its character is not appreciably changed by variations in the velocity of either the gas or the air. a

The provision of a gas burner manifold and flame retention shield of the character and possessing the advantages described above being among the principal objects of the invention, numerous other objects and advantages thereof will become more readily apparent as the following description ensues.

In the accompanying two sheets of drawings forming a part of this specification, one illustrative embodiment of the invention has been shown.

In these drawings: 7

FIG. 1 is an end elevational view of a gas manifold burner assembly constructed in accordance with the principles of the present invention; 7

FIG. 2 is a sectional view taken substantially along the line 2-2 of FIG. 1;

BfilTifiZfl Patented Jan. 23, 1962 FIG. 3 is an enlarged sectional view taken substantially along the line 3--3 of FIG. 2; and

FIG. 4 is an enlarged sectional view taken substantially along the line 4-4 of FIG. 3.

Referring now to the drawings in detail, the improved gas manifold ring and flame retention shield therefor has, as a unitary assembly, been designated in its entirety at it), this assembly being shown operatively applied to a burner construction of the type commonly known as ring burners. The burner construction has been designated in its entirety at 12 and, with the exception of the ring and shield assembly 10, is of more or less conventional design, the illustration thereof made herein being purely exemplary and representing one form of burner assembly with which the ring and shield assembly of the present invention may be associated.

The burner construction or unit 12 is somewhat schematically shown herein and it involves in its general organization a cylindrical burner housing 14 having a medially disposed radial mounting flange l6 thereon by means of which the housing may be attached to a turnnace wall 18 with the forward end region of the housing projecting through the furnace opening 2%. A tubular refractory insert 22 is disposed within the forward end region of the housing 14 and, in effect, comprises a combustion block which establishes an internal combustion chamber 24.

The rear end of the housing 1 is bolted or otherwise secured as at 26 to an air distrubution housing 28 by means of which air for combustion purposes is supplied to the combusition chamber 24-. The air distribution housing 28 provides an involute path 3% extending from an air inlet section 32 having an air damper 34 associated therewith, to a central annular air chamber 36 which is in register with and disposed immediately rearwardly of the manifold ring and shield assembly it). A series of circumferentially spaced air baffle assemblies 38 having operating handles 40 associated therewith exteriorly of the housing 28 serve to prevent extreme swirling motion of the air within the air chamber so that this air may be distributed uniformly over the entire chamber annulus and directed forwardly through the ring burner proper in a manner that will be made clear presently.

The central annular air chamber 36 is established by virtue of a cylindrical distribution duct 41 and a center plug unit 42 comprising a cylindrical shell 44 having a refractory insert 46 in the forward regions thereof and having a circular back plate 48, the marginal or peripheral regions of which are secured by nut and bolt assemblies 50 to the rim region of an opening 52 provided in the rear wall 54 of the air distribution housing 23. The center plug unit 42 is centered Within the distribution duct 41.

The burner ring and shield assembly 10 is comprised of a burner ring proper 6% for supplying combustion gas to the combustion chamber 24, the ring being hereinafter referred to as the gas ring. This gas ring 60 is in the form of a hollow annulus having its axis extending horizontally and provided with a communicating gas inlet connection 62 for a supply pipe 63 in the lower regions thereof. The gas ring 643 is secured within the burner housing 14 by means of a radially disposed retaining ring or plate 64, secured as at 66 to the inner face of the cylindrical housing 14 and to which plate the gas ring may be secured as by welding.

The wall of the annular gas ring 60 is imperforate except for the provision of the gas inlet port 68 which communicates with the gas supply pipe 63 and for the provision of a series of circumferentially spaced radially extending gas discharge ports 7 0 (FIG. 3) which have their axes inclined forwardly and radially inwardly in converging fashion so that gas issuing therefrom will be discharged generally forwardly into the combustion chamber '24 through a series of small gas jets.

The gas ring 60 has associated therewith a flame retention shield 72 in the form of a uniformly cylindrical band or ring which is telescopically received within the gas ring 60 and which preferably makes sealing tangential line contact with the ring as at 74 coextensively around the inner periphery of the ring. The flame retention shield or ring 72 is maintained in its centered position Within the gas ring 69 partly by virtue of its tangential contact with the latter and partly by virtue of a retention shield holder 76 which extends rearwardly from the ring and which may be welded thereto. A heat resistant gasket 78 is interposed between the holder '76 and shield 72, the assembly being held together by a series of clamping bolt and nut assemblies 8t Axial adjustment of the shield '72 relative to the gas ring 6! is made possible by virtue of a series of slots 81 which are formed in the forward edge or rim of the shield. The bolt and nut assemblies 30 pass through these slots and by loosening the bolt and nut assemblies, the axial position of the shield. may be adjusted. It will be understood that such adjustment of the shield is made at the time the original burner installation is effected.

It is to be noted at this point that the positioning of the flame retention shield 72 within the burner gas ring 60 is fairly critical and the positioning thereof will vary with different installations. The exact positioning of the forward open rim of the shield relative to the various gas discharge ports 70 will be a function of the overall diameter of the ring 60, its cross sectional diameter, the angularity of the ports 7%}, their diameters, the pressure of gas maintained within the ring, and other factors. Generally speaking, satisfactory results will be obtained when the extreme forward rim of the cylindrical shield 72 intersects the axes of the various gas discharge openings 70. Stated in other words, the forward rim of the shield 72 is coincident with an imaginary circle which intersects each of the inwardly inclined axes of the gas discharge openings 70. The eifect of adjusting the position of the flame retention ring or shield 72 axially of the burner ring 69 in either direction will be outlined presently after the general operation of the burner system utilizing such a shield has been set forth.

In the operation of the burner assembly 12, gas is supplied to the burner ring 60 at a constant pressure through the inlet port 68 leading from the supply pipe 63. The gas thus introduced into the gas ring 60 is discharged in the form of a series of circumferentially spaced jets into the combustion chamber '24 as previously described. Air enters the air distribution housing 28 through the air inlet section 32, passes through the involute air passage 30 and enters the annular air chamber 36 where it is distributed uniformly around the chamber by means of the various air baffles 38. From thence the air flows forwardly through the annular space or port 82 existing between the annular flame retention shield 72 and the shell 44 of the center plug 42. As the air passes forwardly beyond the extreme forward open rim of the shield 72, a partial vacuum is created within the annular pocket 84 (FIG. 3) which exists immediately forwardly of the tangential line 74 of contact between the shield and gas ring and the creation of such a partial vacuum causes a limited quantity of the air to be drawn radially outwardly from the main air stream issuing from the annular port 82, thus creating eddy currents in and around the vicinity of the pocket 84. These eddy currents of air mix with the gas jets issuing from the gas discharge ports 70. The combined volume of these eddy currents of air is sufiicient to maintain combustion and since these eddy currents are drawn or swept into fairly close proximity to the gas jets, combustion will be initiated at regions which are close to the gas ring. The mixture at this initial region of combustion is rich, due to the fact that the volume of gas greatly exceeds the limited amount 4 of air contained within the eddy currents. Combustion is thus firmly and permanently established at a region which is close to the burner gas ring. The rich mixture which is ignited close to the gas ring behind the shield 72, so to speak, is swept forwardly into the main air stream issuing forwardly from the annular space 82 and combustion is completed at a region within the combustion chamber 24 or within the furnace forwardly of the combustion chamber where considerable turbulence exists.

The proper positioning of the flame retention shield 72 may be ascertained by empirical methods until the proper flame region is established. Thereafter, the damper 34 may be operated to regulate volume of air admitted to the annular air port 82 to regulate the character of the flame as between an extremely rich or an extremely lean mixture. Alternatively, the volume of gas admitted to the gas ring 60 may be varied under the control of a conventional gas cock and, in either event, actual tests with apparatus constructed as described above have established the fact that either the gas or the air may be reduced to 20% of the volume required for stoichiometrical and complete combustion without altering the region of initial flame creation within the flame-producing pocket 84.

Forward shifting of the flame retention shield 72 will effect a less immediate combining of the gas and air so that combustion will take place at a slower rate. Conversely, rearward shifting of the shield 72 will effect a more immediate combination of the gas and air and a consequently more rapid combustion. It has been stated that the proper position of the flame retention shield may be ascertained by empirical methods. It has been found that if the shield 72 is positioned too far forwardly of the ring 60 the shield will be subject to undue heating and possible consequent destruction. On the other hand, if the shield is positioned too far rearwardly, it will be devoid of function. Usually, if the shield is positioned so that its forward rim intersects the axes of the various gas discharge ports 70, satisfactory results will be attained. This is true regardless of the inclination of these axes, providing, or course, the axes of the ports be maintained within operating limits.

The essential operative elements of the improved burner assembly of the present invention have been described above and certain auxiliary instrumentalities such as peepsight, piloting and

electrode devices

92, 94 and 96, respectively, require no detailed description. It is deemed suflicient to state that provision is made for these devices by providing tapped holes in the various casing parts at the required locations or by otherwise securing them in their proper positions.

The invention is not to be limited to the exact arrangement of parts shown in the accompanying drawings or described in this specification as various changes in the details of construction may be resorted to without departing from the spirit of the invention. For example, it will be understood that while the shield 72 has been shown and described herein as being in the form of a continuous ring which is telescopically received within the surrounding gas ring 60 and tangential to the inner periphery of this ring, it is within the purview of the present invention to apply the ring exteriorly of the gas ring with the shield making tangential contact with the outer periphery of the ring. In such an instance, it will be understood that the circumferentially spaced gas ports 70 will be directed forwardly and outwardly of the gas ring with these ports being provided in the outer peripheral regions of the ring. Furthermore, while the gas ring 60 has been shown as being circular in radial cross section, the shape thereof is not critical and the ring may be of oval, rectangular or otherwise polygonal, or other tubular design. Irrespective of such details of design, the essential features of the invention are at all times preserved.

Having thus described the invention what we claim as new and desire to secure by Letters Patent is:

1. In a gas burner construction of the character described, in combination, a tubular burner housing defining an open-ended combustion chamber, a hollow tubular gas ring positioned at the rear end of said combustion chamber and having its outer peripheral region sealed to the rear rim of the latter coextensively therewith, said gas ring having a series of circumferentially spaced jetproducing gas discharge openings formed therein, the axes of said openings being uniformly inclined forwardly and radially inwardly relative to the longitudinal axis of the gas ring, said openings being in communication with the combustion chamber and with the openings being arranged to discharge respective jets of gas into the combustion chamber in a generally forward direction, a substantially cylindrical imperforate open-ended flame retention shield having its axis coincident with the longitudinal axis of the ring, said shield projecting through and making tangential and coextensive sealing line contact with the inner periphery of said ring so that the ring encircles the shield, the forward region of said shield extending forwardly of the tangential line of contact between the shield and ring and defining, in combination with the inner peripheral region of the ring, an annular flame retention pocket which is substantially V-shape in radial cross section and which opens forwardly into the combustion chamber, the forward open rim of the shield being coincident with a circle which intersects all of the axes of said gas discharge openings, means for supplying gas to said gas ring, and means for directing a stream of high velocity air axially and forwardly through said cylindrical shield, and consequently through the ring.

2. In a gas burner construction of the character described, in combination, a tubular burner housing defining an open-ended combustion chamber, a hollow tubular gas ring positioned at the rear end of said combustion chamber and having its outer peripheral region sealed to the rear rim of the latter coextensively therewith, said gas ring having a series of circumferentially spaced jetproducing gas discharge openings formed therein, the axes of said openings being uniformly inclined forwardly and radially inwardly relative to the longitudinal axis of the gas ring, said openings being in communication with the combustion chamber with the openings being arranged to discharge respective jets of gas into the combustion chamber in a generally forward direction, a substantially cylindrical imperforate open-ended flame retention shield having its axis coincident with the longitudinal axis of the ring, said shield projecting through and making tangential and coextensive sealing line contact with the inner periphery of said ring along a circular contact line which is disposed medially between the ends of said cylindrical shield whereby a portion of said shield projects forwardly of the medial plane of the gas ring and defines,

in combination with the outer peripheral regions of the ring, an annular flame-retention pocket which is substantially V-shape in radial cross section and whereby a portion of the shield projects rearwardly of the medial plane of the gas ring, the extreme forward circular rim of said shield being coincident with a circle which intersects all of the axes of said gas discharge openings, a supporting ring for the rear end region of said shield and encompassing the latter, said supporting ring being welded to said gas ring and making sealing contact therewith coextensively therearound, means for directing a stream of high velocity air axially and forwardly through said cylindrical shield, and a heat resistant gasket interposed between said supporting ring and the rear end of the shield.

3. In a gas burner construction of the character describer, in combination, a tubular burner housing defining an open-ended combustion chamber, a hollow tubular gas ring positioned at the rear end of said combustion chamber and having its outer peripheral region sealed to the rear rim of the latter coextensively therewith, said gas ring having a series of circumferentially spaced jet-producing gas discharge openings formed therein, the axes of said openings being uniformly inclined relative to the longitudinal axis of the gas ring, said openings being in communication with the combustion chamber and with the openings being arranged to discharge respective jets of gas into the combustion chamber in a generally forward direction, a shield support fixedly secured to said gas ring, a substantially cylindrical open-ended flame retention shield mounted on said shield support for limited axial sliding movement thereon with the axis of the shield coincident with the axis of said gas ring and with the shield disposed in close proximity to and in sealing relationship with respect to a peripheral region of the gas ring whereby the shield, in any axial position thereof, in combination with the outside surface of the ring, defines an annular flame retention pocket which is substantially V-shape in radial cross section and which opens forwardly into the combustion chamber, means for securing said shield to said shield support in any selected axial position of adjustment, means for supplying gas to said gas ring, and means for directing a stream of high velocity air axially and forwardly through said cylindrical shield and consequently through the gas ring.

References Cited in the file of this patent UNITED STATES PATENTS 1,951,379 Voorheis Mar. 20, 1934 2,559,265 Taylor July 3, 1951 2,587,802 Abrams Mar. 4, 1952 FOREIGN PATENTS 746,061 France Feb. 27, 1933 159,935 Great Britain Mar. 11, 1921